Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 03/24/07

AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
130 PM PDT THU MAR 22 2007 .SYNOPSIS... UPPER LEVEL LOW PRESSURE OFF THE NORTHERN BAJA COAST WILL MOVE SLOWLY INLAND ACROSS NORTHERN AND CENTRAL BAJA CALIFORNIA. MOISTURE WRAPPING AROUND THE NORTH SIDE OF THE LOW WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH FRIDAY...MAINLY ALONG AND EAST OF THE MOUNTAINS. THERE WILL ALSO BE WEAK TO MODERATE OFFSHORE FLOW THROUGH FRIDAY WITH GUSTY WINDS THROUGH AND BELOW PASSES AND CANYONS. FOR THE WEEKEND...HIGH PRESSURE ALOFT WILL BRING FAIR AND WARMER WEATHER TO THE MOUNTAINS AND DESERTS...WHILE AN DEEPENING MARINE LAYER IS EXPECTED WEST OF THE MOUNTAINS. FOR NEXT TUESDAY...A FAST MOVING STORM SYSTEM WILL MOVE INLAND ACROSS CALIFORNIA BRINGING COOLING TO SOUTHWEST CALIFORNIA...STRONG GUSTY WINDS IN THE MOUNTAINS AND DESERTS...AND A CHANCE OF SHOWERS. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (TONIGHT THROUGH SATURDAY)... CLOSED LOW TO THE SOUTH MOVING SLOWLY EAST ACROSS NORTH CENTRAL BAJA AND NORTHERN GULF OF CALIFORNIA THROUGH FRIDAY. LEADING EDGE OF MOISTURE HAS MOVED WEST ACROSS SAN DIEGO COUNTY AND RIVERSIDE COUNTY MOUNTAINS. AT THE NORTHERN END WHERE IT IS CROSSING CENTRAL SAN BERNARDINO COUNTY...SOME LIGHT RAIN SHOWERS ARE OCCURRING...BUT CLOUD BASES ARE FAIRLY HIGH...8-10K FT...SO ONLY A FEW DROPS EXPECTED TO REACH JOHNSTON/LUCERNE VALLEY FLOORS THIS AFTERNOON. A LINE OF THUNDERSTORMS CURRENTLY NEAR THE COLORADO RIVER VALLEY HAS BEEN MOVING STEADILY WEST NORTHWESTWARD. EXTRAPOLATION BRINGS LEADING EDGE TO EASTERN SAN DIEGO COUNTY/COACHELLA VALLEY BY 1630 PDT/2330 UTC. DRY LIGHTNING AND GUSTY DOWNDRAFT WINDS ARE STILL THE MAIN CONCERNS THROUGH AT LEAST 2000 PDT AS THESE THUNDERSTORMS MOVE EAST ACROSS FORECAST AREA. AFTER THAT TIME COLLAPSING THUNDERSTORM TOPS AND ADDITIONAL MID LEVEL MOISTURE ADVECTION FROM DEBRIS CLOUDS COMING IN FROM SOUTHEAST CALIFORNIA SHOULD PRODUCE LIGHT WETTING RAINS. INCREASING SURFACE HUMIDITY OVERNIGHT SHOULD ALSO RETARD GROWTH OF ANY LIGHTNING STARTED FIRES. SOME OF THE CELLS MAY DRIFT ACROSS THE MOUNTAINS OVERNIGHT AND REACH COAST...SO KEPT MENTION OF CHANCE SHOWERS/THUNDERSTORMS FOR THESE ZONES. ON FRIDAY CONVECTIVE ACTIVITY EXPECTED TO BE A LITTLE LESS AND CONFINED TO EAST SLOPES AND DESERTS DUE TO LOW BEING FURTHER EAST WITH NO WRAP AROUND MOISTURE MAKING IT ACROSS MOUNTAINS FRIDAY NIGHT. SATURDAY HIGH PRESSURE RIDGE MOVES OVER THE AREA BUT ONSHORE FLOW WILL END THE WARMING TREND WEST OF THE MOUNTAINS. THE OTHER WEATHER CONCERN TODAY WAS THE EAST TO NORTHEAST WIND GUSTS. THE WIND GUSTS PEAKED BEFORE NOON WITH A FEW STATIONS REPORTING GUSTS TO 35 MPH. SINCE 1100 PDT THE PRESSURE GRADIENT HAS BEEN DIMINISHING. ASIDE FROM DOWNDRAFT GUSTS FROM THUNDERSTORMS...WIND GUSTS SHOULD REMAIN BELOW 35 MPH THROUGH THE NIGHT. && .LONG TERM (SUNDAY THROUGH WEDNESDAY)... THE HIGH PRESSURE RIDGE WILL WEAKEN SUNDAY AND COMPLETELY FLATTEN BY MONDAY. THIS COUPLED WITH A DEEPENING MARINE LAYER SHOULD BRING A COOLING TREND FOR ALL AREAS AS WELL AS INCREASING WINDS ACROSS THE DESERTS AND MOUNTAINS. BY TUESDAY A TROUGH MOVES INLAND TO THE NORTH. MUCH COOLER TEMPERATURES SHOULD LOWER SNOW LEVEL...POSSIBLY IMPACTING CAJON PASS. MAIN EFFECT FOR NOW LOOKS TO BE STRONG WEST WINDS. HIGH PRESSURE REBUILDS WEDNESDAY FOR COOL DRY CONDITIONS. && .AVIATION... 222010Z...LATE MORNING ACARS SOUNDINGS INDICATE THE MARINE LAYER IS TRYING TO BECOME REESTABLISHED OVER THE AREA. AN ACARS SOUNDING OUT OF KSAN SHOWS AN INVERSION AROUND 1600 FEET MSL WHILE ONE OUT OF KSNA SHOWS AN INVERSION AROUND 1300 FEET. NO SIGNS OF ANY STRATUS DEVELOPMENT AT THIS TIME AND NOT EXPECTING ANY THROUGH TONIGHT ALTHOUGH SOME PATCHY STRATUS MAY FORM BY SUNRISE FRIDAY MORNING. WEAK OFFSHORE FLOW AT THE SURFACE AND A NORTHEAST FLOW ALOFT SHOULD KEEP VFR CONDITIONS AT ALL AIRPORTS THROUGH THE NIGHT. VARIABLE AMOUNTS IF MID AND HIGH LEVEL ALTOCU AND CIRRUS WITH BASES MOSTLY ABOVE FL080 SHOULD CONTINUE THROUGH THE NIGHT. THIS MOISTURE IS ASSOCIATED WITH WRAP AROUND MOISTURE FROM AN UPPER LOW OVER NORTHERN BAJA THAT IS DRIFTING SLOWLY TO THE EAST. THUNDERSTORM ACTIVITY OVER WESTERN ARIZONA MAY DRIFT WESTWARD TOWARDS THE DESERT AND MOUNTAIN AREAS BUT THIS ACTIVITY SHOULD DIMINISH AFTER SUNSET. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC/FIRE WEATHER...BALFOUR AVIATION/MARINE.......HORTON NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
900 AM PDT THU MAR 22 2007 .SYNOPSIS... UPPER LEVEL LOW PRESSURE OFF THE NORTHERN BAJA COAST WILL MOVE SLOWLY INLAND ACROSS NORTHERN AND CENTRAL BAJA TONIGHT AND FRIDAY. MOISTURE WRAPPING AROUND THE NORTH SIDE OF THE LOW WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH FRIDAY...MAINLY ALONG AND EAST OF THE MOUNTAINS. THERE WILL ALSO BE WEAK TO MODERATE OFFSHORE FLOW THROUGH FRIDAY WITH GUSTY WINDS THROUGH AND BELOW PASSES AND CANYONS. FOR THE WEEKEND...HIGH PRESSURE ALOFT WILL BRING FAIR AND WARMER WEATHER TO THE MOUNTAINS AND DESERTS...WHILE AN DEEPENING MARINE LAYER IS EXPECTED WEST OF THE MOUNTAINS. FOR NEXT TUESDAY...A FAST MOVING STORM SYSTEM WILL MOVE INLAND ACROSS CALIFORNIA BRINGING COOLING TO SOUTHWEST CALIFORNIA...STRONG GUSTY WINDS IN THE MOUNTAINS AND DESERTS...AND A CHANCE OF SHOWERS. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (TODAY THROUGH SATURDAY)... CLOSED LOW DUE SOUTH OF FORECAST AREA TO MOVE SLOWLY EAST ACROSS NORTH CENTRAL BAJA AND NORTHERN GULF OF CALIFORNIA TODAY THROUGH FRIDAY. MAIN WEATHER THREAT IS WRAP AROUND MOISTURE AND INSTABILITY. A BAND OF ALTO CUMULUS CASTELLANUS CLOUDS IS MOVING UP FROM THE SOUTHEAST THIS MORNING. THUNDERSTORMS ARE LIKELY OVER THE MOUNTAINS AND DESERTS BY EARLY AFTERNOON. PRECIPITATION EXPECTED TO BE FAIRLY LIGHT DURING THE DAY WHICH RAISES THREAT OF DRY LIGHTNING CAUSING FIRE STARTS. ANOTHER WEATHER CONCERN TODAY IS STRENGTH OF WIND GUSTS THROUGH CANYONS AND PASSES. PRESSURE GRADIENTS HAVE TRENDED ABOUT 10 MB OFFSHORE IN THE PAST 24 HOURS. UPSTREAM WINDS FROM SOUNDINGS... VAD WIND PROFILES...AND ACARS SHOW NORTHEAST 20-25 KT IN LOWER 10000 FEET. A FEW RAWS SITES ARE REPORTING GUSTS 25-30 MPH...AND GUSTS COULD INCREASE TO 40 MPH BY LATE MORNING...BUT WITH NORTH-SOUTH PRESSURE GRADIENTS WEAKENING RAPIDLY THIS AFTERNOON AS 1022 MB HIGH OVER GREAT BASIN IS KNOCKED DOWN QUICKLY AND TRANSPORT FLOW ACROSS SOUTHWEST CALIFORNIA BECOMING EAST...WIND GUSTS SHOULD DROP BACK DOWN BELOW 35 MPH BY MIDDAY. WILL CONTINUE TO MONITOR BUT FOR NOW DO NOT PLAN ON ISSUING A WIND ADVISORY. AFTER SUNSET COLLAPSING THUNDERSTORM TOPS AND DEBRIS CLOUDS MOVING IN FROM ARIZONA MAY BRING LIGHT WETTING RAINS THAT MAY DRIFT ACROSS MOUNTAINS AND REACH COAST. ON FRIDAY CONVECTIVE ACTIVITY EXPECTED TO BE A LITTLE LESS AND CONFINED TO EAST SLOPES AND DESERTS DUE TO LOW BEING FURTHER EAST WITH NO WRAP AROUND MOISTURE MAKING IT ACROSS MOUNTAINS FRIDAY NIGHT. SATURDAY HIGH PRESSURE RIDGE MOVES OVER THE AREA BUT ONSHORE FLOW WILL END THE WARMING TREND WEST OF THE MOUNTAINS. && .LONG TERM (SUNDAY THROUGH WEDNESDAY)...FROM PREVIOUS DISCUSSION... HIGH PRESSURE WILL SLOWLY WEAKEN SUNDAY AND MONDAY WITH A SLOW DEEPENING OF THE MARINE LAYER. THIS WILL BRING A SLOW COOLING TREND. FOR TUESDAY...A FAST MOVING PACIFIC STORM SYSTEM WILL MOVE INLAND ACROSS CALIFORNIA. THIS WILL BRING COOLING...STRONG GUSTY WINDS IN THE MOUNTAINS AND DESERTS...A DEEPER MARINE LAYER...AND A CHANCE OF SHOWERS. FAIR AND A LITTLE WARMER FOR WEDNESDAY AS LOW PRESSURE MOVES EAST. && .AVIATION... 221430Z...OFFSHORE FLOW AND NORTHEAST TO EASTERLY FLOW ALOFT OVER THE AREA WILL KEEP THE MARINE LAYER DISRUPTED TODAY. UPPER LOW OFF THE COAST OF NORTHERN BAJA WILL BRING WRAP AROUND MOISTURE ACROSS THE AREA THROUGH THIS EVENING. THIS WILL RESULT IN VARIABLE AMOUNTS OF MID AND HIGH LEVEL MOISTURE OVER THE AREA WITH SCATTERED TO BROKEN ALTOCU AND CIRRUS ABOVE 10000 FEET OVER THE AREA. THE AIR MASS IS SOMEWHAT UNSTABLE AND WITH AFTERNOON SURFACE HEATING THERE COULD BE ISOLATED THUNDERSTORMS ESPECIALLY OVER THE MOUNTAINS THROUGH SUNSET THIS EVENING. THE MARINE LAYER IS NOT EXPECTED TO RECOVER TONIGHT SO AIRPORTS SHOULD REMAIN VFR THROUGH FRIDAY. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC/FIRE WEATHER...BALFOUR AVIATION/MARINE.......HORTON NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
330 AM CDT THU MAR 22 2007 .DISCUSSION FOR AFTERNOON ZONES/GRIDS... 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... 1254 AM CDT VIGOROUS S/WV TROF PROPAGATING ACROSS NRN PLAINS AND UPPER MIDWEST EARLY THIS MORNING...WITH ASSOCIATED SFC TROF/COLD FRONT FROM NRN WI TO ERN IA AT 05Z. REGIONAL PROFILER DATA...AND 0445Z ACARS SOUNDING OUT OF KRFD INDICATE 55 KT SOUTHWESTERLY LLJ IN 930-850 HPA LAYER AHEAD OF LOW LEVEL TROF/FRONT. SOUNDING ALSO INDICATES STEEP LAPSE RATES IN THIS LAYER...THOUGH A BIT OF A CAP NOTED AROUND 670 MB. ISOLATED WEAK ELEVATED CONVECTIVE CELLS HAVE BEEN TRYING TO INITIATE IN THIS REGION OF MOIST/WAA ACROSS FAR NRN IL...THOUGH APPEARS THEY ARE FIGHTING CAP. NAM FCST SOUNDINGS DEPICT COOLING OF MID/UPR LVLS WITH APPROACH OF S/WV EARLY THIS MORNING HOWEVER...WITH ELEVATED CAPE INCREASING TO 550-650 J/KG FOR PARCELS BASED 875-900 HPA. THIS ALONG WITH INCREASING LLVL CONVERGENCE AHEAD OF FRONT SHOULD BE SUFFICIENT TO RESULT IN SCATTERED TRW AS BOUNDARY ADVANCES ACROSS FCST IL. CURRENT REGIONAL RADAR TRENDS INDICATE STRONG CONVECTION IN SWRN WI AND SRN IA...WITH SOME INCREASE IN CELL DEVELOPMENT ACROSS ERN IA. GIVEN STRONG FAIRLY UNIDIRECTIONAL WIND FIELD MAY SEE SOME GUSTS IN 40 KT RANGE WITH TSTMS...AND PERHAPS SOME SMALL HAIL GIVEN MARGINAL CAPE PROFILES. THUS WILL MAINTAIN TS IN TERMINALS THIS MORNING...MAINLY DURG 09-13Z PERIOD FROM WEST TO EAST AS FRONT MOVES THRU. MAY SEE BRIEF PERIOD OF MVFR CIGS IN FRONTAL ZONE...THOUGH STRONG LLVL DRYING BEHIND FRONT SHOULD DECREASE CLOUDS FAIRLY RAPIDLY WITH VFR CONDITIONS PREVAILING WITHIN A FEW HOURS OF SUNRISE. STRONG SW LLVL WIND FIELD IN TIGHT PRES GRADIENT AHEAD OF COLD FRONT RESULTING IN GUSTY 20-30 KT WINDS ATTM. WILL SEE GRADIENT DECREASE JUST A BIT WITHIN TROF AXIS TOWARD SUNRISE...THEN WSHFT TO NWLY DIRECTION. SOME GUSTINESS AS SFC PRES RISE BUILDS IN EARLY MORNING...THEN DECREASING WINDS THIS AFTN AS WEAK SFC HIGH BUILDS IN. DVLPMNT OF NE WINDS OFF LAKE A GOOD PROBABILITY VERY LATE AFTN/EARLY EVE AS GRADIENT WINDS DECREASE. NEXT S/WV AND ELEVATED PCPN THREAT BEYOND 06Z TONIGHT...MORE ON THAT WITH NEXT FCST ISSUANCE. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1254 AM CDT THU MAR 22 2007 .DISCUSSION FOR AFTERNOON ZONES/GRIDS... 315 PM CDT SFC ANALYSIS AT 19Z INDICATED LOW PRES CENTERED OVR KS/NE WITH WARM FRONT EXTENDING EWD ACROSS IOWA AND NRN IL. QUITE A DRAMATIC TEMP DIFFERENCE ACROSS OUR CWA THIS AFTN AS IN THE WARM SECTOR (S OF I-80) TEMPS HAVE CLIMBED WELL INTO THE 70S. ADDITIONAL CLOUD COVER TO THE NORTH HAS LIMITED INSOLATION AND KEPT EXTREME NRN IL IN THE 60S. DEWPTS WERE GENERALLY IN THE UPR 50S ACROSS THE AREA. INSTABILITY AND SHEAR ARE BOTH MARGINAL FOR SEVERE WITH CAPE AROUND 500 J/KG AND DEEP LAYER SHEAR APPROACHING 30KTS. ONE ROUND OF STORMS CROSSING NWRN IL ATTM...SHOULD CLIP THE REGION NW OF A MENDOTA TO WAUKEGAN LINE THROUGH EARLY EVENING. ANTICIPATE A SUBSEQUENT LULL THIS EVENING...BEFORE NEXT ROUND OF STORMS ARRIVES LATE TONIGHT ACCOMPANYING THE COLD FRONT WHICH IS HEADED THIS WAY FROM THE DAKOTAS. MODELS POINTING AT STRONG DIFFLUENCE AT H2 AND SIGNIFICANT H5 SHORTWAVE ENERGY ACCOMPANYING THE FROPA. WITH VERY MOIST AIR OUT AHEAD OF THIS BOUNDARY....POTENTIAL FOR HEAVY RAIN EXISTS THROUGH THE NIGHT. STRONG WIND FIELDS WILL KEEP STORM MOTION FAIRLY BRISK AND WITH LATE EVENING BREAK IN THE ACTION...THIS SHOULD PREVENT MUCH AREAL FLOOD CONCERN...THOUGH RIVERS WILL EXPERIENCE SOME RISES IN RESPONSE TO THIS PRECIP. FROPA WILL BE DELAYED TIL THURSDAY AFTN SOUTH OF I-80. WEAK HIGH TRIES TO BUILD IN THURS NT. PRECIP WILL NOT BE FAR TO THE S THOUGH...WITH BOUNDARY LINGERING ACROSS CENTRAL IL/INDY. NRN AND SRN STREAMS OF H2 JET EVENTUALLY SYNC UP ACROSS IL/WI BY SAT AS SFC BOUNDARY LIFTS NWD INTO NRN IL. THIS WILL LEAD TO A WET WEEKEND ACROSS THE LOCAL AREA. DETAILS IMPOSSIBLE TO DISCERN THIS FAR OUT WITH SUCH A COMPLICATED (BUT OBVIOUSLY WET) SITUATION...BUT WITH LONGWAVE TROUGH IN THE WRN CONUS AND RIDGE AXIS TO OUR EAST...WE`LL SEE RECURRING MID AND UPR TROPOSPHERIC SHORTWAVE TROUGHS RIPPLING THROUGH THE AREA THROUGH EARLY TUESDAY...WITH COLD FRONT USHERING IN DRIER AIR BEYOND THAT AS PER THE GFS MODEL. ECMWF IS SLIGHTLY SLOWER WITH THAT FROPA AND WOULD KEEP PRECIP AROUND THROUGH TUES. NEXT MAJOR SYSTEM SHOWN BY GLOBAL MODELS TO DEVELOP OVR THE NRN PLAINS BY WED...BRINGING MORE PRECIP. TEMPS GENERALLY ABV NORMAL THROUGH THE FCST PERIOD. WELCOME TO SPRING! RRH .AVIATION... 1254 AM CDT VIGOROUS S/WV TROF PROPAGATING ACROSS NRN PLAINS AND UPPER MIDWEST EARLY THIS MORNING...WITH ASSOCIATED SFC TROF/COLD FRONT FROM NRN WI TO ERN IA AT 05Z. REGIONAL PROFILER DATA...AND 0445Z ACARS SOUNDING OUT OF KRFD INDICATE 55 KT SOUTHWESTERLY LLJ IN 930-850 HPA LAYER AHEAD OF LOW LEVEL TROF/FRONT. SOUNDING ALSO INDICATES STEEP LAPSE RATES IN THIS LAYER...THOUGH A BIT OF A CAP NOTED AROUND 670 MB. ISOLATED WEAK ELEVATED CONVECTIVE CELLS HAVE BEEN TRYING TO INITIATE IN THIS REGION OF MOIST/WAA ACROSS FAR NRN IL...THOUGH APPEARS THEY ARE FIGHTING CAP. NAM FCST SOUNDINGS DEPICT COOLING OF MID/UPR LVLS WITH APPROACH OF S/WV EARLY THIS MORNING HOWEVER...WITH ELEVATED CAPE INCREASING TO 550-650 J/KG FOR PARCELS BASED 875-900 HPA. THIS ALONG WITH INCREASING LLVL CONVERGENCE AHEAD OF FRONT SHOULD BE SUFFICIENT TO RESULT IN SCATTERED TRW AS BOUNDARY ADVANCES ACROSS FCST IL. CURRENT REGIONAL RADAR TRENDS INDICATE STRONG CONVECTION IN SWRN WI AND SRN IA...WITH SOME INCREASE IN CELL DEVELOPMENT ACROSS ERN IA. GIVEN STRONG FAIRLY UNIDIRECTIONAL WIND FIELD MAY SEE SOME GUSTS IN 40 KT RANGE WITH TSTMS...AND PERHAPS SOME SMALL HAIL GIVEN MARGINAL CAPE PROFILES. THUS WILL MAINTAIN TS IN TERMINALS THIS MORNING...MAINLY DURG 09-13Z PERIOD FROM WEST TO EAST AS FRONT MOVES THRU. MAY SEE BRIEF PERIOD OF MVFR CIGS IN FRONTAL ZONE...THOUGH STRONG LLVL DRYING BEHIND FRONT SHOULD DECREASE CLOUDS FAIRLY RAPIDLY WITH VFR CONDITIONS PREVAILING WITHIN A FEW HOURS OF SUNRISE. STRONG SW LLVL WIND FIELD IN TIGHT PRES GRADIENT AHEAD OF COLD FRONT RESULTING IN GUSTY 20-30 KT WINDS ATTM. WILL SEE GRADIENT DECREASE JUST A BIT WITHIN TROF AXIS TOWARD SUNRISE...THEN WSHFT TO NWLY DIRECTION. SOME GUSTINESS AS SFC PRES RISE BUILDS IN EARLY MORNING...THEN DECREASING WINDS THIS AFTN AS WEAK SFC HIGH BUILDS IN. DVLPMNT OF NE WINDS OFF LAKE A GOOD PROBABILITY VERY LATE AFTN/EARLY EVE AS GRADIENT WINDS DECREASE. NEXT S/WV AND ELEVATED PCPN THREAT BEYOND 06Z TONIGHT...MORE ON THAT WITH NEXT FCST ISSUANCE. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
924 PM EDT FRI MAR 23 2007 .EVENING UPDATE... WEAKENING IMPULSE MOVING FROM MO INTO SOUTH CENTRAL IL AND SOUTHERN IN ALONG THE PERIPHERY OF THE STRONG 587 H500 RIDGE CENTERED NEAR THE DESTIN FLA COASTLINE. SCATTERED SHOWER ACTIVITY SHOULD REACH THE SOUTHERN INDIANA AND NORTH CENTRAL COUNTIES WEST OF INTERSTATE 65 BEFORE LOSING COVERAGE AS IT MOVES TOWARDS INTERSTATE 75 AND THE LEXINGTON METRO AREA. THEREFORE WILL RAISE POPS IN THE NORTHWESTERN THIRD OF THE FORECAST AREA FROM SCOTTSBURG INDIANA SOUTHWEST TO HAWESVILLE KENTUCKY. WILL MAKE TWEAKS TO CLOUDS TO CATCH CURRENT TRENDS...WILL ADJUST LOWER ACROSS THE SOUTH WHERE FEW TO SCT MID LVL CLOUDS ARE BEING FOUND...SMALL UPWARD TWEAK OF ABOUT 2 DEGREES LOOKS NEEDED FOR OVERNIGHT LOWS WITH DEWPOINTS IN THE MID AND UPPER 50S AND SOME CLOUDS IT WILL BE HARD FOR MUCH OF THE AREA TO DROP MUCH BELOW 60...MORE THAN 20 DEGREES ABOVE THE NORMAL LOW AND NEAR OR JUST ABOVE THE NORMAL HIGHS FOR THE DAY!. SCHOTT && .PREV DISCUSSION... /ISSUED 731 PM EDT FRI MAR 23 2007/ AVIATION DISCUSSION (00Z TAFS)... IMPULSES RUNNING ALONG THE FRONTAL BOUNDARY TO THE NORTH STILL BRINGING SMALL PERIODS OF SCATTERED SHOWERS TO THE REGION. THOUGH WITH THAT POSSIBILITY WILL NOT MENTION SHRA AT ANY ONE TAF SITE...WILL MENTION VCSH DURING THE PERIODS WHERE SHOWERS LOOK POSSIBLE. HAVE KEPT VFR THROUGHOUT THE ENTIRE TAF PERIOD AT ALL THREE SITES...WITH MID LVL CIGS AT BOTH SDF AND LEX THROUGH MUCH OF THE PERIOD BEFORE 15Z...LOW OR MID LVL CIGS NOT LIKELY AT BWG. NON CONVECTIVE WINDS SHEAR LOOKS TO CREEP JUST ABOVE THE THRESHOLD TONIGHT AND HAVE IT AT ALL THREE SITES. CURRENT ACARS SOUNDING SHOWS A 30 TO 35 KT LL JET AROUND 2000 FT. --SCHOTT PREV DISCUSSION... /ISSUED 245 PM EDT FRI MAR 23 2007/ SHORT TERM (TNGT AND SAT) MAY-LIKE TEMPS IN MAR WITH FRONT FROM IND TO SRN OH ATTM TO STAY WELL TO OUR NORTH. WEAKENING AREA OF SHOWERS TO AFFECT MAINLY THE NRN HALF OF OUR FA LATE THIS AFTN...THESE AHD OF UPR IMPLSE RIDING EWD ON SRN EDGE OF WESTERLIES. WOULD ONLY EXPECT ABOUT .10 OF AN INCH OVER OUR SRN INDIANA COUNTIES BY 00Z THIS EVE WITH LIGHTER AMOUNTS SOUTHWARD TO NEAR THE OHIO RIVER ACRS NCNTRL KY AND THE NRN BLUEGRASS REGION. A SECOND IMPLSE COMING NEWD IN DIFFLUENT FLO...ATTM ACRS ERN OK... IS SPAWNING A NEW MCS ACRS SERN KS/MO. THIS IMPLSE FCST TO TAKE A SIMILAR PATH AS THE AFOREMENTIONED ONE...WHILE WEAKENING. WILL THEREFORE KEEP CHC POPS IN THE FCST TNGT...HIEST N-LOWEST S WITH NO POPS ACRS SCNTRL KY. ONE LAST IMPLSE TOPS THE RIDGE SAT AS IT MOVES FROM NEAR STL TO NEAR LOU BY SUN EVE. GFS FCST A BIT MORE UNSTABLE AMS(LIFTED INDICES NEAR -2)AHD OF THIS FEATURE...WILL LEAVE THUNDER IN THE FCST AND SIMILAR CHC POPS TO GOING FCST...AGAIN HIEST ACRS OUR NRN MOST FA. WITH BUILDING RIDGE...AND ONLY MID/HIGH CLDS ACRS OUR SRN FA SAT...CANT ARGUE AGAINST MAX TEMPS ARND 80...WITH TEMPS TEMPERED A BIT NRN FA BY LOWER CLDS AND SCT SHOWERS/STMS. DK LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... SATURDAY NIGHT THROUGH MONDAY NIGHT... HIGHLY AMPLIFIED UPPER AIR PATTERN IS FORECAST ACROSS NORTH AMERICA DURING THIS TIME PERIOD. LARGE UPPER LOW OVER THE SOUTHWEST UNITED STATES IS FORECAST TO LIFT NORTHEASTWARD INTO THE UPPER PLAINS AS LARGE H5 RIDGE HOLDS SWAY ACROSS THE EASTERN THIRD OF THE US. BY LATE IN THIS TIME PERIOD...00Z GFS ENSEMBLE MEANS SHOW DEEPENING H5 TROF COMING INTO THE WESTERN CONUS WHICH WILL HELP KICK OR FLATTEN THE EAST COAST RIDGE SOMEWHAT. AT THE SFC...SFC WARM FRONTAL BOUNDARY WILL BE TO OUR NORTH AND REMAIN THERE THROUGH THIS PORTION OF THE FCST PERIOD. SEVERAL WEAK VORTS WILL LIKELY CRUISE THROUGH WITHIN THE MEAN FLOW AND AROUND THE H5 RIDGE. THE GFS SOLUTIONS KEEP MUCH OF THE PRECIP NORTH OF HERE...WHILE THE NAM-WRF SOLUTIONS AREA BIT FURTHER SOUTH. WITH NO REAL FORCING MECHANISM...DO NOT SEE MUCH OF A CHANCE OF MEASURABLE PRECIPITATION THROUGH MONDAY MORNING. BY MONDAY...WITH FLATTENING RIDGE AND A SFC HIGH TO OUR EAST...GOOD FLOW OF WARM MOIST AIR WILL PUSH IN AND DIURNAL CONVECTION SHOULD GET GOING BY THE AFTERNOON. FOR NOW WILL KEEP LOW CHANCE POPS IN THE FCST. TEMPERATURES THROUGH THE PERIOD WILL BE WAY ABOVE NORMAL...FEELING LIKE LATE MAY OR EARLY JUNE. STUCK CLOSE THE ENSEMBLE MEANS FOR TEMPERATURES WITH OVERNIGHT LOWS IN THE MID AND UPPER 50S. HIGHS IN THE UPPER 70S TO AROUND 80 IN THE NORTH FOR SUNDAY LOOK LIKE A GOOD BET...WITH LOWER 80S ACROSS THE CENTRAL AND SOUTHERN TIERS. WITH MORE CLOUDS AND POSSIBLE CONVECTION IN THE AREA MONDAY...TEMPERATURES SHOULD BE A LITTLE COOLER...BUT WILL STILL BE SOME 10-15 DEGREES ABOVE AVERAGE WITH HIGHS IN THE UPPER 70S. TUESDAY THROUGH FRIDAY... MAIN FORECAST CHALLENGE HERE WILL BE POP CHANCES. GIVEN THAT THE PATTERN LOOKS LIKE ONE OF LATE MAY TO EARLY JUNE...DIURNALLY DRIVEN CONVECTION APPEARS TO BE THE MAIN WEATHER MAKER THROUGH THURSDAY. FOR NOW WILL KEEP LOW CHC POPS IN THE AFTERNOON AND EARLY EVENING HOURS. BY THURSDAY...UPPER AIR PATTERN IS FORECAST TO BECOME MORE ZONAL WITH TIME AS STRONG MID-LAT CYCLONE DEVELOPS AND HEADS NE INTO THE SOUTHERN CANADA. ASSOCIATED SFC COLD FRONT IS PROGGED TO PUSH INTO THE REGION LATE THU AND DURING THE DAY ON FRIDAY WHICH WILL BRING A PERIOD OF WIDESPREAD RAIN AND STORMS TO THE AREA. WHILE MAIN FORCING WILL BE NORTH OF THE REGION...OVERALL PATTERN LOOKS INTERESTING FOR A ROUND OF CONVECTIVE WEATHER. SOMETHING TO WATCH OVER THE NEXT FEW DAYS. WARM WEATHER IS EXPECTED TO CONTINUE THROUGH THE PERIOD. STRONG SOUTHERLY FLOW WILL KEEP TEMPERATURES RATHER WARM THROUGH THE PERIOD WITH HIGHS IN THE MID TO UPPER 70S AND OVERNIGHT LOWS IN THE LOW TO MID 50S. THIS IS FAIRLY CLOSE TO THE LATEST ENSEMBLE MEANS AND THE ONGOING FORECAST....SO ONLY SOME MINOR ADJUSTMENTS WILL WERE NEEDED. -MJ LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
731 PM EDT FRI MAR 23 2007 .AVIATION DISCUSSION (00Z TAFS)... IMPULSES RUNNING ALONG THE FRONTAL BOUNDARY TO THE NORTH STILL BRINGING SMALL PERIODS OF SCATTERED SHOWERS TO THE REGION. THOUGH WITH THAT POSSIBILITY WILL NOT MENTION SHRA AT ANY ONE TAF SITE...WILL MENTION VCSH DURING THE PERIODS WHERE SHOWERS LOOK POSSIBLE. HAVE KEPT VFR THROUGHOUT THE ENTIRE TAF PERIOD AT ALL THREE SITES...WITH MID LVL CIGS AT BOTH SDF AND LEX THROUGH MUCH OF THE PERIOD BEFORE 15Z...LOW OR MID LVL CIGS NOT LIKELY AT BWG. NON CONVECTIVE WINDS SHEAR LOOKS TO CREEP JUST ABOVE THE THRESHOLD TONIGHT AND HAVE IT AT ALL THREE SITES. CURRENT ACARS SOUNDING SHOWS A 30 TO 35 KT LL JET AROUND 2000 FT. --SCHOTT && .PREV DISCUSSION... /ISSUED 245 PM EDT FRI MAR 23 2007/ SHORT TERM (TNGT AND SAT) MAY-LIKE TEMPS IN MAR WITH FRONT FROM IND TO SRN OH ATTM TO STAY WELL TO OUR NORTH. WEAKENING AREA OF SHOWERS TO AFFECT MAINLY THE NRN HALF OF OUR FA LATE THIS AFTN...THESE AHD OF UPR IMPLSE RIDING EWD ON SRN EDGE OF WESTERLIES. WOULD ONLY EXPECT ABOUT .10 OF AN INCH OVER OUR SRN INDIANA COUNTIES BY 00Z THIS EVE WITH LIGHTER AMOUNTS SOUTHWARD TO NEAR THE OHIO RIVER ACRS NCNTRL KY AND THE NRN BLUEGRASS REGION. A SECOND IMPLSE COMING NEWD IN DIFFLUENT FLO...ATTM ACRS ERN OK... IS SPAWNING A NEW MCS ACRS SERN KS/MO. THIS IMPLSE FCST TO TAKE A SIMILAR PATH AS THE AFOREMENTIONED ONE...WHILE WEAKENING. WILL THEREFORE KEEP CHC POPS IN THE FCST TNGT...HIEST N-LOWEST S WITH NO POPS ACRS SCNTRL KY. ONE LAST IMPLSE TOPS THE RIDGE SAT AS IT MOVES FROM NEAR STL TO NEAR LOU BY SUN EVE. GFS FCST A BIT MORE UNSTABLE AMS(LIFTED INDICES NEAR -2)AHD OF THIS FEATURE...WILL LEAVE THUNDER IN THE FCST AND SIMILAR CHC POPS TO GOING FCST...AGAIN HIEST ACRS OUR NRN MOST FA. WITH BUILDING RIDGE...AND ONLY MID/HIGH CLDS ACRS OUR SRN FA SAT...CANT ARGUE AGAINST MAX TEMPS ARND 80...WITH TEMPS TEMPERED A BIT NRN FA BY LOWER CLDS AND SCT SHOWERS/STMS. DK LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... SATURDAY NIGHT THROUGH MONDAY NIGHT... HIGHLY AMPLIFIED UPPER AIR PATTERN IS FORECAST ACROSS NORTH AMERICA DURING THIS TIME PERIOD. LARGE UPPER LOW OVER THE SOUTHWEST UNITED STATES IS FORECAST TO LIFT NORTHEASTWARD INTO THE UPPER PLAINS AS LARGE H5 RIDGE HOLDS SWAY ACROSS THE EASTERN THIRD OF THE US. BY LATE IN THIS TIME PERIOD...00Z GFS ENSEMBLE MEANS SHOW DEEPENING H5 TROF COMING INTO THE WESTERN CONUS WHICH WILL HELP KICK OR FLATTEN THE EAST COAST RIDGE SOMEWHAT. AT THE SFC...SFC WARM FRONTAL BOUNDARY WILL BE TO OUR NORTH AND REMAIN THERE THROUGH THIS PORTION OF THE FCST PERIOD. SEVERAL WEAK VORTS WILL LIKELY CRUISE THROUGH WITHIN THE MEAN FLOW AND AROUND THE H5 RIDGE. THE GFS SOLUTIONS KEEP MUCH OF THE PRECIP NORTH OF HERE...WHILE THE NAM-WRF SOLUTIONS AREA BIT FURTHER SOUTH. WITH NO REAL FORCING MECHANISM...DO NOT SEE MUCH OF A CHANCE OF MEASURABLE PRECIPITATION THROUGH MONDAY MORNING. BY MONDAY...WITH FLATTENING RIDGE AND A SFC HIGH TO OUR EAST...GOOD FLOW OF WARM MOIST AIR WILL PUSH IN AND DIURNAL CONVECTION SHOULD GET GOING BY THE AFTERNOON. FOR NOW WILL KEEP LOW CHANCE POPS IN THE FCST. TEMPERATURES THROUGH THE PERIOD WILL BE WAY ABOVE NORMAL...FEELING LIKE LATE MAY OR EARLY JUNE. STUCK CLOSE THE ENSEMBLE MEANS FOR TEMPERATURES WITH OVERNIGHT LOWS IN THE MID AND UPPER 50S. HIGHS IN THE UPPER 70S TO AROUND 80 IN THE NORTH FOR SUNDAY LOOK LIKE A GOOD BET...WITH LOWER 80S ACROSS THE CENTRAL AND SOUTHERN TIERS. WITH MORE CLOUDS AND POSSIBLE CONVECTION IN THE AREA MONDAY...TEMPERATURES SHOULD BE A LITTLE COOLER...BUT WILL STILL BE SOME 10-15 DEGREES ABOVE AVERAGE WITH HIGHS IN THE UPPER 70S. TUESDAY THROUGH FRIDAY... MAIN FORECAST CHALLENGE HERE WILL BE POP CHANCES. GIVEN THAT THE PATTERN LOOKS LIKE ONE OF LATE MAY TO EARLY JUNE...DIURNALLY DRIVEN CONVECTION APPEARS TO BE THE MAIN WEATHER MAKER THROUGH THURSDAY. FOR NOW WILL KEEP LOW CHC POPS IN THE AFTERNOON AND EARLY EVENING HOURS. BY THURSDAY...UPPER AIR PATTERN IS FORECAST TO BECOME MORE ZONAL WITH TIME AS STRONG MID-LAT CYCLONE DEVELOPS AND HEADS NE INTO THE SOUTHERN CANADA. ASSOCIATED SFC COLD FRONT IS PROGGED TO PUSH INTO THE REGION LATE THU AND DURING THE DAY ON FRIDAY WHICH WILL BRING A PERIOD OF WIDESPREAD RAIN AND STORMS TO THE AREA. WHILE MAIN FORCING WILL BE NORTH OF THE REGION...OVERALL PATTERN LOOKS INTERESTING FOR A ROUND OF CONVECTIVE WEATHER. SOMETHING TO WATCH OVER THE NEXT FEW DAYS. WARM WEATHER IS EXPECTED TO CONTINUE THROUGH THE PERIOD. STRONG SOUTHERLY FLOW WILL KEEP TEMPERATURES RATHER WARM THROUGH THE PERIOD WITH HIGHS IN THE MID TO UPPER 70S AND OVERNIGHT LOWS IN THE LOW TO MID 50S. THIS IS FAIRLY CLOSE TO THE LATEST ENSEMBLE MEANS AND THE ONGOING FORECAST....SO ONLY SOME MINOR ADJUSTMENTS WILL WERE NEEDED. -MJ .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
1050 AM EDT THU MAR 22 2007 .SHORT TERM 15Z UPDATE... WRM FRNT IS CONT TO MOVE NE THRU CWA PER ERLR FCST PROJ. KIAD 12Z SNDG HAD 45 KTS AT THE TAIL OF 950 MB JET. THIS FEATURE IS GOING TO MOVE NE AHEAD OF WRM FRNT...BUT WL STILL HAVE 30 KTS AT PEAK HEATING BTWN 18-20Z THIS AFT. SO THIS AFT WL SEE A GSTY 35 MPH WIND THAT WILL CONT THRU THIS EVNG. VSBL SATL IMGRY HAS CIGS OVC020 MOVING OFF THE WESTRN SHORE OF THE CHESPKE INTO DELMARV WTH CLRNG BEHIND. SHRA/TSRA IN OH VLY ONGOING ATTM IS PROGGED TO REACH WSTRN CWA LATE THIS AFT 22Z TIMEFRAME...BUT WITH DOWNSLOPE AND LACK OF CAPE DO NOT XPECT TSRA FOR CWA THIS EVENING BUT A REAL GOOD CHC OF SHRA ACTIVITY BETWEEN 6 PM AND MIDNIGHT. && .SHORT TERM (TODAY THROUGH TONIGHT) FROM PREV DISC... WATER VAPOR LOOP SHOWS A RIDGE CENTERED OVER THE GULF STATES EXTENDS NORTHEAST INTO NEW ENGLAND. AN UPPER LOW IS SPINNING NEAR SOUTHERN CALIFORNIA...WHILE THE NEXT STRONG SHORT WAVE EMBEDDED WITHIN THE NORTHERN STREAM ACROSS THE UPPER MIDWEST DIVES SOUTHEAST. ACARS 400-250MB WIND OBSERVATIONS REVEAL LIGHT FLOW ALOFT ACROSS THE EASTERN CONUS...WITH PHASING BETWEEN THE TWO STREAMS EVIDENT ACROSS SOUTH CENTRAL CANADA. 03Z SURFACE ANALYSIS PLACED A WARM/STATIONARY BOUNDARY FROM A TRIPLE POINT IN NORTH CENTRAL WISCONSIN SOUTHEAST THROUGH THE EASTERN GREAT LAKES AND ALONG THE APPALACHIANS...THEN EAST-NORTHEAST ACROSS THE CAROLINAS. THE NEXT COLD FRONT STRETCHED SOUTHWEST FROM THE TRIPLE POINT THROUGH THE PLAINS. EXPECT OVERRUNNING ABOVE THE SURFACE BOUNDARY ACROSS THE CAROLINAS TO ALLOW LOW STRATUS TO CONTINUE TO INVADE FROM SOUTHEAST VIRGINIA EARLY THIS MORNING UNDERNEATH A LOWERING INVERSION INDUCED BY WARM ADVECTION ALOFT (AS SHOWN BY 0407Z ACARS SOUNDING FROM KIAD VS. 00Z KIAD RAOB). MEANWHILE...SCATTERED TO BROKEN MID LEVEL CLOUDS ARE STREAMING NORTHEAST ALONG THE APPALACHIANS. AS THE WARM FRONT LIFTS NORTHEAST OF THE FORECAST AREA...EXPECT LOW STRATUS TO LIFT AND BREAK. OPTED WITH AN OPTIMISTIC PARTLY SUNNY SKY WORDING TO ACCOUNT FOR THE PERIOD BETWEEN DISSIPATING MORNING STRATUS AND INVADING MOISTURE ALOFT. FOR TEMPERATURES...STARTED WITH THE GFS MOS...AND RAISED TEMPERATURES ACROSS THE SOUTHWESTERN ZONES...WHERE IF THERE IS A PERIOD OF SUNSHINE MIXING SHOULD SUPPORT EVEN WARMER TEMPERATURES IN THE UPPER 70S. COOLEST READINGS SHOULD BE ACROSS THE BALTIMORE METRO AREA. DO NOT EXPECT TO SEE A SOLENOIDAL BAY BREEZE CIRCULATION TODAY GIVEN A STRONG PRESSURE GRADIENT AHEAD OF THE COLD FRONT. WINDS COULD GUST TO 30 MPH WITHIN THE WARM SECTOR (RAOB/ACARS AND KLWX VAD ALL SHOW PLENTY OF MOMENTUM JUST OFF THE SURFACE...AND KHSP HAS BEEN GUSTING NEAR 25KT ALL NIGHT). REGARDING PRECIPITATION...HAVE TIMED IN SHOWERS ASSOCIATED WITH WARM ADVECTION AHEAD OF THE NEXT COLD FRONT DURING THE EVENING HOURS...POSSIBLY AS EARLY AS LATE THIS AFTERNOON ACROSS THE NORTHWEST ZONES (USING THE 21Z SHORT RANGE ENSEMBLES). THE 00Z LWX WRF-NMM SIMULATED REFLECTIVITY INDICATES PRECIPITATION MOVING ACROSS THE ALLEGHENY FRONT AROUND 21Z. INCLUDED MENTION OF THUNDER AS CONVECTION SUPPORTED BY INSTABILITY ACROSS THE OHIO VALLEY MAY MAKE IT OVER THE MOUNTAINS IN AN EMBEDDED FASHION. INSTABILITY WAS MORE IMPRESSIVE ON 00Z GFS BUFKIT FORECAST SOUNDINGS...WHILE THE 00Z NAM INDICATED NEAR NIL INSTABILITY. THIS TREND IS ALSO SUPPORTED BY THE MODEL OUTPUT OF THE SHOWALTER INDEX...WHERE THE NAM IS SLIGHTLY POSITIVE...WHEREAS THE GFS IS NEGATIVE NOT ONLY LATE THIS AFTERNOON...BUT THROUGH THE EVENT EARLY TONIGHT. THERE MAY BE SOME AREAS OF LIGHT FOG WHICH DEVELOP AFTER RAIN SHOWERS SATURATE THE BOUNDARY LAYER...SINCE THE COLD FRONT WILL BE LAGGING BEHIND. THIS IS SUPPORTED BY THE GFS MOS. OPTED TO START WITH ETA MOS TEMPERATURES TONIGHT...AS IT TYPICALLY DOES BETTER IN PREFRONTAL REGIMES. DID COOL OFF THE NORTHERN FORECAST AREA CLOSER TO DEW POINTS AS THIS AREA HAS THE BEST CHANCE OF SEEING PRECIPITATION. && .AVIATION... MVFR STRATUS LAST EVENING WAS ERODED FROM THE SOUTHWEST AS THE WARM FRONT ALOFT MOVED THROUGH THE REGION (AS SHOWN BY 0407Z ACARS SOUNDING FROM KIAD VS. 00Z KIAD RAOB). CONTINUED WARM ADVECTION ABOVE THE SURFACE FRONTAL BOUNDARY ACROSS THE CAROLINAS WILL TEND TO SATURATE THE LAYER UNDER A LOWER INVERSION EARLY THIS MORNING. EXPECT LOW STRATUS TO ROLL BACK INTO KCHO AND THE METRO HUBS FROM SOUTHEAST VIRGINIA BEFORE SUNRISE. WARM FRONT WILL LIFT NORTHEAST THROUGH THE FORECAST AREA DURING THE MORNING...RESULTING IN LIFTING CEILINGS AND ALLOWING SOUTHWEST WIND GUSTS TO MIX TO THE SURFACE. WARM ADVECTION AHEAD OF THE NEXT COLD FRONT WILL PRESENT SEVERAL HOURS OF LIGHT RAIN SHOWERS TO THE REGION DURING THE EVENING. AS A HEADS UP...THERE COULD BE SOME LIGHT FOG DEVELOPMENT AS RAIN SATURATES THE BOUNDARY LAYER TONIGHT...AS WINDS SLACKEN AHEAD OF THE APPROACHING COLD FRONT. && .MARINE... 00Z ETA/GFS MOS AT THOMAS POINT INDICATE SUSTAINED WINDS OF 15-20KTS THIS AFTERNOON INTO TONIGHT. BOTH 00Z NAM/GFS PROXIMITY FORECAST SOUNDINGS INDICATE ADDITIONAL WIND GUST POTENTIAL OF 25-30KTS DURING THE SAME TIME PERIOD. DESPITE STABILITY INDUCED BY THE COLD WATER VS. WARM AIR...SUSTAINED WINDS ALONE WILL PRODUCE WINDS IN THE SMALL CRAFT CRITERIA RANGE. IN ADDITION...BELIEVE INFREQUENT WIND GUSTS OF 25KTS WILL BE ABLE TO BREAK THROUGH SHALLOW INVERSION LAYER. THIS IS SUPPORTED BY THE 00Z LWX 6KM WRF-NMM BUFKIT FORECAST SOUNDINGS OVER THE WATER. EVENING SHOWERS MAY SERVE TO STABILIZE THE BOUNDARY LAYER AS THE GRADIENT SLACKENS AHEAD OF THE APPROACHING COLD FRONT. THERE STILL MAY BE SMALL CRAFT ADVISORY WINDS OVERNIGHT ACROSS THE LOWER TIDAL POTOMAC AND CHESAPEAKE BAY NEAR THE VIRGINA STATE LINE SHOULD SHOWERS STAY NORTH OF THAT AREA. NO FLAGS ARE EXPECTED AT THIS TIME FOR THE LONG TERM PORTION OF THE MARINE FCST. ONSHORE FLOW AT TIMES WILL NEED TO BE MONITORED FOR PTNL HIGH TIDAL DEPARTURES. && .LONG TERM... FRIDAY THROUGH WEDNESDAY... FRONTAL BNDRY AND WAVY LOW PRES AREAS WILL AFFECT THE MID ATLC FRI THROUGH SAT NGT WITH SEVERAL BOUTS OF RNFL LIKELY. THE BEST CHCS FOR RAIN WILL BE CLOSER TO THE MASON/DIXON LINE WHILE LOCATIONS IN CENTRAL VIRGINIA AND LOWER SOUTHERN MD WILL ONLY SEE SLGT CHCS FOR RAINFALL. DURING THIS PERIOD ONSHORE FLOW BELOW 925 MB WILL FEED ABUNDANT LOW LVL MOISTURE WHILE MID LVL FLOW WILL BE FAIRLY PROGRESSIVE. THUS BOUTS OF SHOWERY WEATHER LIKELY MOST LIKELY ACROSS MUCH OF MD INCLUDING THE BALTIMORE AREA WITH LESSER CHCS ACROSS NORTHERN VA AND WASHINGTON DC. NOTED ONSHORE FLOW ON FRI NGT AND SAT WILL BRING MUCH COOLER MAX TEMPS ON SAT AND THE LATEST MOS SLTNS ARE NOT MUCH OF A SLTN WITH ROUGHLY A 20 DEG SPREAD IN MAX TEMPS. FOR THIS FCST RUN HAVE LEANED MORE WITH THE GFS MOS TEMPS THROUGH THE SHORT TERM WHICH ARE SUPPORTIVE OF WEDGE LIKE CONDS ON SAT E OF THE BLUE RIDGE WITH WARMER TEMPS SOUTH AND IN THE PTMC HIGHLANDS. FROM LATE SAT NGT THROUGH TUE HIGH PRES WILL KEEP THE CHCS FOR PRECIPITATION QUITE LOW. HWVR BOUTS OF ONSHORE FLOW WILL KEEP TEMPS IN CHECK WITH HIGHS GNRLY IN THE 60S MOST DAYS. STILL A GOOD BIT OF UNCERTAINTY IN THE LONG TERM TEMPS...HIGHLY DEPENDANT ON WHEN ONSHORE FLOW DEVELOPS OR DISSIPATES. ATTM HAVE GONE CLOSE TO THE LATEST EXTENDED MOS GUIDANCE TEMPS. A COLD FRONT WILL AFFECT THE REGION TUE NGT AND WED BRINGING ANOTHER CHC FOR RAIN. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 10 PM EDT THIS EVENING FOR ANZ530>537. && $$ SHORT TERM UPDATE...LEE SHORT TERM/AVIATION...ROGOWSKI LONG TERM...BROTHERTON MARINE...ROGOWSKI/BROTHERTON
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
400 AM EDT THU MAR 22 2007 .SHORT TERM (TODAY THROUGH TONIGHT)... WATER VAPOR LOOP SHOWS A RIDGE CENTERED OVER THE GULF STATES EXTENDS NORTHEAST INTO NEW ENGLAND. AN UPPER LOW IS SPINNING NEAR SOUTHERN CALIFORNIA...WHILE THE NEXT STRONG SHORT WAVE EMBEDDED WITHIN THE NORTHERN STREAM ACROSS THE UPPER MIDWEST DIVES SOUTHEAST. ACARS 400-250MB WIND OBSERVATIONS REVEAL LIGHT FLOW ALOFT ACROSS THE EASTERN CONUS...WITH PHASING BETWEEN THE TWO STREAMS EVIDENT ACROSS SOUTH CENTRAL CANADA. 03Z SURFACE ANALYSIS PLACED A WARM/STATIONARY BOUNDARY FROM A TRIPLE POINT IN NORTH CENTRAL WISCONSIN SOUTHEAST THROUGH THE EASTERN GREAT LAKES AND ALONG THE APPALACHIANS...THEN EAST-NORTHEAST ACROSS THE CAROLINAS. THE NEXT COLD FRONT STRETCHED SOUTHWEST FROM THE TRIPLE POINT THROUGH THE PLAINS. EXPECT OVERRUNNING ABOVE THE SURFACE BOUNDARY ACROSS THE CAROLINAS TO ALLOW LOW STRATUS TO CONTINUE TO INVADE FROM SOUTHEAST VIRGINIA EARLY THIS MORNING UNDERNEATH A LOWERING INVERSION INDUCED BY WARM ADVECTION ALOFT (AS SHOWN BY 0407Z ACARS SOUNDING FROM KIAD VS. 00Z KIAD RAOB). MEANWHILE...SCATTERED TO BROKEN MID LEVEL CLOUDS ARE STREAMING NORTHEAST ALONG THE APPALACHIANS. AS THE WARM FRONT LIFTS NORTHEAST OF THE FORECAST AREA...EXPECT LOW STRATUS TO LIFT AND BREAK. OPTED WITH AN OPTIMISTIC PARTLY SUNNY SKY WORDING TO ACCOUNT FOR THE PERIOD BETWEEN DISSIPATING MORNING STRATUS AND INVADING MOISTURE ALOFT. FOR TEMPERATURES...STARTED WITH THE GFS MOS...AND RAISED TEMPERATURES ACROSS THE SOUTHWESTERN ZONES...WHERE IF THERE IS A PERIOD OF SUNSHINE MIXING SHOULD SUPPORT EVEN WARMER TEMPERATURES IN THE UPPER 70S. COOLEST READINGS SHOULD BE ACROSS THE BALTIMORE METRO AREA. DO NOT EXPECT TO SEE A SOLENOIDAL BAY BREEZE CIRCULATION TODAY GIVEN A STRONG PRESSURE GRADIENT AHEAD OF THE COLD FRONT. WINDS COULD GUST TO 30 MPH WITHIN THE WARM SECTOR (RAOB/ACARS AND KLWX VAD ALL SHOW PLENTY OF MOMENTUM JUST OFF THE SURFACE...AND KHSP HAS BEEN GUSTING NEAR 25KT ALL NIGHT). REGARDING PRECIPITATION...HAVE TIMED IN SHOWERS ASSOCIATED WITH WARM ADVECTION AHEAD OF THE NEXT COLD FRONT DURING THE EVENING HOURS...POSSIBLY AS EARLY AS LATE THIS AFTERNOON ACROSS THE NORTHWEST ZONES (USING THE 21Z SHORT RANGE ENSEMBLES). THE 00Z LWX WRF-NMM SIMULATED REFLECTIVITY INDICATES PRECIPITATION MOVING ACROSS THE ALLEGHENY FRONT AROUND 21Z. INCLUDED MENTION OF THUNDER AS CONVECTION SUPPORTED BY INSTABILITY ACROSS THE OHIO VALLEY MAY MAKE IT OVER THE MOUNTAINS IN AN EMBEDDED FASHION. INSTABILITY WAS MORE IMPRESSIVE ON 00Z GFS BUFKIT FORECAST SOUNDINGS...WHILE THE 00Z NAM INDICATED NEAR NIL INSTABILITY. THIS TREND IS ALSO SUPPORTED BY THE MODEL OUTPUT OF THE SHOWALTER INDEX...WHERE THE NAM IS SLIGHTLY POSITIVE...WHEREAS THE GFS IS NEGATIVE NOT ONLY LATE THIS AFTERNOON...BUT THROUGH THE EVENT EARLY TONIGHT. THERE MAY BE SOME AREAS OF LIGHT FOG WHICH DEVELOP AFTER RAIN SHOWERS SATURATE THE BOUNDARY LAYER...SINCE THE COLD FRONT WILL BE LAGGING BEHIND. THIS IS SUPPORTED BY THE GFS MOS. OPTED TO START WITH ETA MOS TEMPERATURES TONIGHT...AS IT TYPICALLY DOES BETTER IN PREFRONTAL REGIMES. DID COOL OFF THE NORTHERN FORECAST AREA CLOSER TO DEW POINTS AS THIS AREA HAS THE BEST CHANCE OF SEEING PRECIPITATION. && .AVIATION... MVFR STRATUS LAST EVENING WAS ERODED FROM THE SOUTHWEST AS THE WARM FRONT ALOFT MOVED THROUGH THE REGION (AS SHOWN BY 0407Z ACARS SOUNDING FROM KIAD VS. 00Z KIAD RAOB). CONTINUED WARM ADVECTION ABOVE THE SURFACE FRONTAL BOUNDARY ACROSS THE CAROLINAS WILL TEND TO SATURATE THE LAYER UNDER A LOWER INVERSION EARLY THIS MORNING. EXPECT LOW STRATUS TO ROLL BACK INTO KCHO AND THE METRO HUBS FROM SOUTHEAST VIRGINIA BEFORE SUNRISE. WARM FRONT WILL LIFT NORTHEAST THROUGH THE FORECAST AREA DURING THE MORNING...RESULTING IN LIFTING CEILINGS AND ALLOWING SOUTHWEST WIND GUSTS TO MIX TO THE SURFACE. WARM ADVECTION AHEAD OF THE NEXT COLD FRONT WILL PRESENT SEVERAL HOURS OF LIGHT RAIN SHOWERS TO THE REGION DURING THE EVENING. AS A HEADS UP...THERE COULD BE SOME LIGHT FOG DEVELOPMENT AS RAIN SATURATES THE BOUNDARY LAYER TONIGHT...AS WINDS SLACKEN AHEAD OF THE APPROACHING COLD FRONT. && .MARINE... 00Z ETA/GFS MOS AT THOMAS POINT INDICATE SUSTAINED WINDS OF 15-20KTS THIS AFTERNOON INTO TONIGHT. BOTH 00Z NAM/GFS PROXIMITY FORECAST SOUNDINGS INDICATE ADDITIONAL WIND GUST POTENTIAL OF 25-30KTS DURING THE SAME TIME PERIOD. DESPITE STABILITY INDUCED BY THE COLD WATER VS. WARM AIR...SUSTAINED WINDS ALONE WILL PRODUCE WINDS IN THE SMALL CRAFT CRITERIA RANGE. IN ADDITION...BELIEVE INFREQUENT WIND GUSTS OF 25KTS WILL BE ABLE TO BREAK THROUGH SHALLOW INVERSION LAYER. THIS IS SUPPORTED BY THE 00Z LWX 6KM WRF-NMM BUFKIT FORECAST SOUNDINGS OVER THE WATER. EVENING SHOWERS MAY SERVE TO STABILIZE THE BOUNDARY LAYER AS THE GRADIENT SLACKENS AHEAD OF THE APPROACHING COLD FRONT. THERE STILL MAY BE SMALL CRAFT ADVISORY WINDS OVERNIGHT ACROSS THE LOWER TIDAL POTOMAC AND CHESAPEAKE BAY NEAR THE VIRGINA STATE LINE SHOULD SHOWERS STAY NORTH OF THAT AREA. NO FLAGS ARE EXPECTED AT THIS TIME FOR THE LONG TERM PORTION OF THE MARINE FCST. ONSHORE FLOW AT TIMES WILL NEED TO BE MONITORED FOR PTNL HIGH TIDAL DEPARTURES. && .LONG TERM... FRIDAY THROUGH WEDNESDAY... FRONTAL BNDRY AND WAVY LOW PRES AREAS WILL AFFECT THE MID ATLC FRI THROUGH SAT NGT WITH SEVERAL BOUTS OF RNFL LIKELY. THE BEST CHCS FOR RAIN WILL BE CLOSER TO THE MASON/DIXON LINE WHILE LOCATIONS IN CENTRAL VIRGINIA AND LOWER SOUTHERN MD WILL ONLY SEE SLGT CHCS FOR RAINFALL. DURING THIS PERIOD ONSHORE FLOW BELOW 925 MB WILL FEED ABUNDANT LOW LVL MOISTURE WHILE MID LVL FLOW WILL BE FAIRLY PROGRESSIVE. THUS BOUTS OF SHOWERY WEATHER LIKELY MOST LIKELY ACROSS MUCH OF MD INCLUDING THE BALTIMORE AREA WITH LESSER CHCS ACROSS NORTHERN VA AND WASHINGTON DC. NOTED ONSHORE FLOW ON FRI NGT AND SAT WILL BRING MUCH COOLER MAX TEMPS ON SAT AND THE LATEST MOS SLTNS ARE NOT MUCH OF A SLTN WITH ROUGHLY A 20 DEG SPREAD IN MAX TEMPS. FOR THIS FCST RUN HAVE LEANED MORE WITH THE GFS MOS TEMPS THROUGH THE SHORT TERM WHICH ARE SUPPORTIVE OF WEDGE LIKE CONDS ON SAT E OF THE BLUE RIDGE WITH WARMER TEMPS SOUTH AND IN THE PTMC HIGHLANDS. FROM LATE SAT NGT THROUGH TUE HIGH PRES WILL KEEP THE CHCS FOR PRECIPITATION QUITE LOW. HWVR BOUTS OF ONSHORE FLOW WILL KEEP TEMPS IN CHECK WITH HIGHS GNRLY IN THE 60S MOST DAYS. STILL A GOOD BIT OF UNCERTAINTY IN THE LONG TERM TEMPS...HIGHLY DEPENDANT ON WHEN ONSHORE FLOW DEVELOPS OR DISSIPATES. ATTM HAVE GONE CLOSE TO THE LATEST EXTENDED MOS GUIDANCE TEMPS. A COLD FRONT WILL AFFECT THE REGION TUE NGT AND WED BRINGING ANOTHER CHC FOR RAIN. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 10 PM EDT THIS EVENING FOR ANZ530>537. && $$ SHORT TERM/AVIATION...ROGOWSKI LONG TERM...BROTHERTON MARINE...ROGOWSKI/BROTHERTON
AREA FORECAST DISCUSSION
NWS GAYLORD MI
130 PM EDT FRI MAR 23 2007 .AVIATION...SURFACE HIGH PRESSURE WILL KEEP A VERY DRY AIRMASS WITHIN THE LOW LEVELS IN PLACE THROUGH THE AFTERNOON AND EVENING HOURS...MAINTAINING THE VFR CONDITIONS AT ALL LOCATIONS. HOWEVER...MID-LEVEL MOISTURE WILL CONTINUE TO PRODUCE A SCT-BKN090 DECK...MOSTLY AFFECTING PLN...WITH A MORE SCT SCENARIO AT APN. A SHORTWAVE MOVING OVER THE GREAT PLAINS WILL TRACK TOWARD THE GREAT LAKES OVERNIGHT...AND WILL HELP TO DRAW LOW LEVEL MOISTURE NORTHWARD...AND PRODUCE MVFR CONDITIONS AT ALL TAF SITES LATE OVERNIGHT THROUGH TOMORROW MORNING. STILL SOME QUESTION HOW FAR NORTH THIS LOW LEVEL MOISTURE WILL PENETRATE THE DRY AIR CURRENTLY IN PLACE. MPC && .UPDATE...ISSUED AT 1232 PM FLOOD HEADLINES EXTENDED THROUGH EARLY SATURDAY MORNING. ADAM && .UPDATE...ISSUED AT 1104 AM. SFC ANALYSIS REVEALING BROAD HIGH PRESSURE ACROSS THE GREAT LAKES ALONG WITH A FAIRLY DRY AIRMASS (PWAT RUNNING AROUND 0.3 INCH OFF 12Z APX SOUNDING). AREA OF THICKER MID CLOUD ASSOCIATED WITH WEAK SHORT WAVE (PER WATER VAPOR IMAGERY) DRIFTING THROUGH THE NRN PORTION OF THE CWA THIS MORNING AND WILL BRING A PERIOD OF BKN SKIES PRIMARILY TO EASTERN UPPER MICHIGAN. OTHERWISE...ABUNDANT SUNSHINE IN STORE FOR THE REST OF THE CWA THIS AFTERNOON WITH TEMPERATURES JUST GETTING INTO THE 50S. LIGHT WINDS (925 MB WINDS UNDER 15 KNOTS) SHOULD RESULT IN LAKE BREEZE COMPONENT THIS AFTERNOON AND KEEP TEMPS A LITTLE COOLER FOR THE SHORELINE AREAS. OVERALL...ONLY MINOR TWEAKS MADE TO GOING FORECAST...AND UPDATE ALREADY SENT. HYDRO CONCERNS...USGS GAGE READINGS ON THE TOBACCO AND RIFLE RIVERS STILL GOING UP (ABOVE BANKFULL STAGE ON THE RIFLE RIVER NEAR STERLING). HOWEVER TREND HAS FLATTENED OUT THIS MORNING INDICATING THE RIVER LEVELS LIKELY NEARING PEAK. NONETHELESS...WILL TAKE AT LEAST ANOTHER DAY TO GET THE WATER THROUGH THE SYSTEM AND THE LEVELS BACK DOWN AGAIN. WILL MAKE SOME CALLS TO THE AREA AND CHECK FORECAST DATA...BUT ONGOING FLOOD WATCH AND WARNINGS WILL LIKELY NEED EXTENDING THROUGH TONIGHT AND PERHAPS SATURDAY. ADAM && .DISCUSSION...ISSUED AT 257 AM. SPLIT FLOW IN PLACE ACROSS THE CONUS WITH THE GREAT LAKES BENEATH CONFLUENCE AXIS WHERE NORTHERN AND SOUTHERN BRANCHES MERGE BACK TOGETHER. NORTHERN BRANCH SHORT WAVE TROUGH CURRENTLY CROSSING THE NORTHERN ROCKIES EXPECTED TO CROSS THE REGION SATURDAY...MEANWHILE PERSISTENT SOUTHERN BRANCH UPPER LOW CURRENTLY CROSSING MEXICO FORECAST TO FILL AND LIFT NORTHEAST THIS WEEKEND...BUCKLING THE SOUTHERN BRANCH FLOW WHICH IN TURN WILL PROBABLY SEND THE EAST-WEST ORIENTED FRONTAL BOUNDARY OVER THE OHIO/MISSISSIPPI RIVER VALLEYS NORTHWARD. SO ATTENTION ON WEEKEND WEATHER POTENTIAL WILL BE THE MAIN FORECAST ISSUES THIS MORNING. TODAY/TONIGHT...MIDNIGHT SURFACE ANALYSIS SHOWS A SMALL BUBBLE OF HIGH PRESSURE OVER THE WESTERN LAKES...WITH MAIN FRONTAL BOUNDARY DRAPED ACROSS THE OHIO/MISSISSIPPI RIVER VALLEYS. CONVECTION FIRING ALONG THE FRONT BUT REMAINING MOSTLY SOUTH OF THE LOWER PENINSULA. WATER VAPOR IMAGERY SHOWS AN ELONGATED SHORT WAVE TROUGH CROSSING NORTHERN WI...AREA OF MID CLOUD OUT AHEAD OF THIS FEATURES ACROSS UPPER AND SPREADING INTO NORTHERN LOWER MI. 00Z RAOBS FROM APX/GRB WERE FAIRLY DRY (700MB DEW POINT DEPRESSIONS 14C). 03Z AIRCRAFT SOUNDING OUT OF PLN HAS MOISTENED A BIT IN THE MID LEVELS...BUT STILL DRY BELOW 700MB. AREA RADARS SHOWING SOME WEAK RETURNS CROSSING NORTHERN LAKE MICHIGAN...NO REPORTS OF ANYTHING REACHING THE GROUND WITH CEILING HEIGHTS IN THE 9-10K FOOT RANGE. SHORT WAVE TROUGH SHOULD ZIP THROUGH THE AREA EARLY THIS MORNING WITH LITTLE FANFARE OTHER THAN AN INCREASE IN MID CLOUD...WHICH SHOULD DIMINISH LATER THIS MORNING THOUGH THERE MAY BE SOME RESIDUAL CLOUD COVER HANGING ON ACROSS UPPER MI/STRAITS THROUGH THE DAY. SHOULD BE A GOOD DAY FOR LAKE BREEZE DEVELOPMENT AS WELL WITH WEAK GRADIENT IN PLACE...AND MILD AS WELL WITH AFTERNOON HIGHS RUNNING A GOOD 10 DEGREES ABOVE NORMAL. NORTHERN STREAM SHORT WAVE TROUGH EXPECTED TO APPROACH THE WESTERN LAKES BY SATURDAY MORNING. LOOKING FOR AN INCREASE IN MID/HIGH CLOUDS MAINLY ACROSS THE NORTHERN HALF OF THE FORECAST AREA TONIGHT IN ADVANCE OF THIS FEATURE. AS FOR THE CURRENT HYDROLOGIC ISSUES...PROBABLY ALL RIGHT TO DROP FLOOD WATCH FOR MANISTEE/WEXFORD COUNTIES...IF WE`RE GOING TO SEE FLOOD PROBLEMS FROM WEDNESDAY NIGHT`S RAINFALL EVENT PROBABLY WOULD HAVE SEEN THEM BY NOW. WILL KEEP THE FLOOD WATCH GOING FOR GLADWIN/ARENAC COUNTIES WHERE RIVER LEVELS ARE STILL TRENDING UPWARD...WITH FLOOD WARNING FOR ARENAC COUNTY ALONG RIFLE RIVER WHICH IS STILL RUNNING NEAR BANKFULL STAGE (9 FEET) THOUGH HYDROGRAPH SHOWING SIGNS OF RIVER NEARING CREST. SATURDAY...AFOREMENTIONED SHORT WAVE TROUGH WILL SWING ACROSS NORTHERN MI DURING THE DAY SATURDAY...WILL LIKELY BE EAST OF THE FORECAST AREA BY EVENING. SHOULD SEE MORE CLOUD COVER ACROSS NORTHERN MI SATURDAY AT LEAST THROUGH MID AFTERNOON...BUT WILL PROBABLY SEE SOME CLEARING BY LATE AFTERNOON IN WAKE OF THIS WAVE. WON`T RULE OUT SOME LIGHT PRECIP ACROSS EASTERN UPPER AND THE TIP OF THE MITT...LOWER LAYERS STILL FORECAST TO BE PRETTY DRY SO MAY JUST END UP WITH A GOOD DEAL OF VIRGA (LIKE EARLY THIS MORNING). DEEP LAYER RIDGING/ANTICYCLONIC FLOW THEN BUILD INTO THE WESTERN LAKES SATURDAY NIGHT IN THE WAKE OF THE NORTHERN STREAM WAVE...AND AHEAD OF SOUTHERN BRANCH LOW WHICH WILL BE CLIMBING UP THE WESTERN SIDE OF THIS RIDGE THROUGH THE HIGH PLAINS. LOOKING AT A QUIET SATURDAY NIGHT WITH RIDGING AND DRY AIR IN PLACE. SUNDAY THROUGH TUESDAY...FOR SUNDAY...WITH UPPER LEVEL PATTERN BECOMING MORE AMPLIFIED THIS WILL RE-ORIENT PERSISTENT FRONTAL BOUNDARY ACROSS THE OHIO/MISSISSIPPI VALLEYS FROM EAST-WEST TO NORTHWEST-SOUTHEAST AS WESTERN END OF THE FRONT GETS PUSHED NORTH ACROSS IA AND INTO MN/SOUTHERN WI. DRY AIR WILL STILL HANG ON MUCH OF THE DAY...BETTER MOIST INFLOW MAY NOT GET FOCUSED TOWARD LOWER MI UNTIL SUNDAY NIGHT...SO MUCH OF THE DAY SHOULD BE DRY AND MILD WITH PERHAPS JUST A LATE CHANCE FOR PRECIPITATION WEST OF M-37. WILL CARRY THUNDERSTORM CHANCES ALL AREAS FOR SUNDAY NIGHT WITH LOW LEVEL JET FOCUSED ON THE FORECAST AREA. MONDAY RAIN CHANCES STILL LOOK FINE THOUGH MAY END UP BEING MORE OF A MORNING ISSUE. TUESDAY FORECAST PROBABLY A BIT MORE UP IN THE AIR DEPENDING ON WHETHER FRONTAL BOUNDARY PUSHES THROUGH THE STATE OR GETS HUNG UP IF HEIGHT FALLS ARE NOT AS IMPRESSIVE AS INDICATED BY 22/12Z ECMWF OUTPUT. GIVEN THIS CONFLICT SEE NO NEED TO CHANGE CURRENT CHANCE POPS FOR TUESDAY (THOUGH WILL EXPAND TO COVER ALL AREAS). JPB && .APX WATCHES/WARNINGS/ADVISORIES...FLOOD WATCH...THROUGH EARLY SATURDAY MORNING...MIZ041-042. FLOOD WARNING...THROUGH EARLY SATURDAY MORNING...MIZ042. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1232 PM EDT FRI MAR 23 2007 .UPDATE...FLOOD HEADLINES EXTENDED THROUGH EARLY SATURDAY MORNING. ADAM && .UPDATE...ISSUED AT 1104 AM. SFC ANALYSIS REVEALING BROAD HIGH PRESSURE ACROSS THE GREAT LAKES ALONG WITH A FAIRLY DRY AIRMASS (PWAT RUNNING AROUND 0.3 INCH OFF 12Z APX SOUNDING). AREA OF THICKER MID CLOUD ASSOCIATED WITH WEAK SHORT WAVE (PER WATER VAPOR IMAGERY) DRIFTING THROUGH THE NRN PORTION OF THE CWA THIS MORNING AND WILL BRING A PERIOD OF BKN SKIES PRIMARILY TO EASTERN UPPER MICHIGAN. OTHERWISE...ABUNDANT SUNSHINE IN STORE FOR THE REST OF THE CWA THIS AFTERNOON WITH TEMPERATURES JUST GETTING INTO THE 50S. LIGHT WINDS (925 MB WINDS UNDER 15 KNOTS) SHOULD RESULT IN LAKE BREEZE COMPONENT THIS AFTERNOON AND KEEP TEMPS A LITTLE COOLER FOR THE SHORELINE AREAS. OVERALL...ONLY MINOR TWEAKS MADE TO GOING FORECAST...AND UPDATE ALREADY SENT. HYDRO CONCERNS...USGS GAGE READINGS ON THE TOBACCO AND RIFLE RIVERS STILL GOING UP (ABOVE BANKFULL STAGE ON THE RIFLE RIVER NEAR STERLING). HOWEVER TREND HAS FLATTENED OUT THIS MORNING INDICATING THE RIVER LEVELS LIKELY NEARING PEAK. NONETHELESS...WILL TAKE AT LEAST ANOTHER DAY TO GET THE WATER THROUGH THE SYSTEM AND THE LEVELS BACK DOWN AGAIN. WILL MAKE SOME CALLS TO THE AREA AND CHECK FORECAST DATA...BUT ONGOING FLOOD WATCH AND WARNINGS WILL LIKELY NEED EXTENDING THROUGH TONIGHT AND PERHAPS SATURDAY. ADAM && .AVIATION...ISSUED AT 722 AM. VFR CONDITIONS SET TO PREVAIL ACROSS ALL TAF SITES OVER THE NEXT 24 HOURS AS HIGH PRESSURE SLOWLY TRAVERSES THE REGION. EARLY MORNING SCT-BKN 9KFT MID CLOUD DECK WILL GIVE WAY TO SOME SCATTERED CIRRUS BY MID MORNING. WITH LIGHT SYNOPTIC WIND REGIME UNDER HIGH PRESSURE...EXPECTING LAKE BREEZES TO KICK IN OFF LAKES MICHIGAN AND HURON DURING THE AFTERNOON. BIGGEST INFLUENCE EXPECTED AT TVC AND PLN WHERE LIGHT SOUTHEAST WINDS SHOULD QUICKLY VEER MORE WEST (PLN) TO NORTH (TVC) WITH PASSAGE OF LAKE FRONT. MSB && .DISCUSSION...ISSUED AT 257 AM. SPLIT FLOW IN PLACE ACROSS THE CONUS WITH THE GREAT LAKES BENEATH CONFLUENCE AXIS WHERE NORTHERN AND SOUTHERN BRANCHES MERGE BACK TOGETHER. NORTHERN BRANCH SHORT WAVE TROUGH CURRENTLY CROSSING THE NORTHERN ROCKIES EXPECTED TO CROSS THE REGION SATURDAY...MEANWHILE PERSISTENT SOUTHERN BRANCH UPPER LOW CURRENTLY CROSSING MEXICO FORECAST TO FILL AND LIFT NORTHEAST THIS WEEKEND...BUCKLING THE SOUTHERN BRANCH FLOW WHICH IN TURN WILL PROBABLY SEND THE EAST-WEST ORIENTED FRONTAL BOUNDARY OVER THE OHIO/MISSISSIPPI RIVER VALLEYS NORTHWARD. SO ATTENTION ON WEEKEND WEATHER POTENTIAL WILL BE THE MAIN FORECAST ISSUES THIS MORNING. TODAY/TONIGHT...MIDNIGHT SURFACE ANALYSIS SHOWS A SMALL BUBBLE OF HIGH PRESSURE OVER THE WESTERN LAKES...WITH MAIN FRONTAL BOUNDARY DRAPED ACROSS THE OHIO/MISSISSIPPI RIVER VALLEYS. CONVECTION FIRING ALONG THE FRONT BUT REMAINING MOSTLY SOUTH OF THE LOWER PENINSULA. WATER VAPOR IMAGERY SHOWS AN ELONGATED SHORT WAVE TROUGH CROSSING NORTHERN WI...AREA OF MID CLOUD OUT AHEAD OF THIS FEATURES ACROSS UPPER AND SPREADING INTO NORTHERN LOWER MI. 00Z RAOBS FROM APX/GRB WERE FAIRLY DRY (700MB DEW POINT DEPRESSIONS 14C). 03Z AIRCRAFT SOUNDING OUT OF PLN HAS MOISTENED A BIT IN THE MID LEVELS...BUT STILL DRY BELOW 700MB. AREA RADARS SHOWING SOME WEAK RETURNS CROSSING NORTHERN LAKE MICHIGAN...NO REPORTS OF ANYTHING REACHING THE GROUND WITH CEILING HEIGHTS IN THE 9-10K FOOT RANGE. SHORT WAVE TROUGH SHOULD ZIP THROUGH THE AREA EARLY THIS MORNING WITH LITTLE FANFARE OTHER THAN AN INCREASE IN MID CLOUD...WHICH SHOULD DIMINISH LATER THIS MORNING THOUGH THERE MAY BE SOME RESIDUAL CLOUD COVER HANGING ON ACROSS UPPER MI/STRAITS THROUGH THE DAY. SHOULD BE A GOOD DAY FOR LAKE BREEZE DEVELOPMENT AS WELL WITH WEAK GRADIENT IN PLACE...AND MILD AS WELL WITH AFTERNOON HIGHS RUNNING A GOOD 10 DEGREES ABOVE NORMAL. NORTHERN STREAM SHORT WAVE TROUGH EXPECTED TO APPROACH THE WESTERN LAKES BY SATURDAY MORNING. LOOKING FOR AN INCREASE IN MID/HIGH CLOUDS MAINLY ACROSS THE NORTHERN HALF OF THE FORECAST AREA TONIGHT IN ADVANCE OF THIS FEATURE. AS FOR THE CURRENT HYDROLOGIC ISSUES...PROBABLY ALL RIGHT TO DROP FLOOD WATCH FOR MANISTEE/WEXFORD COUNTIES...IF WE`RE GOING TO SEE FLOOD PROBLEMS FROM WEDNESDAY NIGHT`S RAINFALL EVENT PROBABLY WOULD HAVE SEEN THEM BY NOW. WILL KEEP THE FLOOD WATCH GOING FOR GLADWIN/ARENAC COUNTIES WHERE RIVER LEVELS ARE STILL TRENDING UPWARD...WITH FLOOD WARNING FOR ARENAC COUNTY ALONG RIFLE RIVER WHICH IS STILL RUNNING NEAR BANKFULL STAGE (9 FEET) THOUGH HYDROGRAPH SHOWING SIGNS OF RIVER NEARING CREST. SATURDAY...AFOREMENTIONED SHORT WAVE TROUGH WILL SWING ACROSS NORTHERN MI DURING THE DAY SATURDAY...WILL LIKELY BE EAST OF THE FORECAST AREA BY EVENING. SHOULD SEE MORE CLOUD COVER ACROSS NORTHERN MI SATURDAY AT LEAST THROUGH MID AFTERNOON...BUT WILL PROBABLY SEE SOME CLEARING BY LATE AFTERNOON IN WAKE OF THIS WAVE. WON`T RULE OUT SOME LIGHT PRECIP ACROSS EASTERN UPPER AND THE TIP OF THE MITT...LOWER LAYERS STILL FORECAST TO BE PRETTY DRY SO MAY JUST END UP WITH A GOOD DEAL OF VIRGA (LIKE EARLY THIS MORNING). DEEP LAYER RIDGING/ANTICYCLONIC FLOW THEN BUILD INTO THE WESTERN LAKES SATURDAY NIGHT IN THE WAKE OF THE NORTHERN STREAM WAVE...AND AHEAD OF SOUTHERN BRANCH LOW WHICH WILL BE CLIMBING UP THE WESTERN SIDE OF THIS RIDGE THROUGH THE HIGH PLAINS. LOOKING AT A QUIET SATURDAY NIGHT WITH RIDGING AND DRY AIR IN PLACE. SUNDAY THROUGH TUESDAY...FOR SUNDAY...WITH UPPER LEVEL PATTERN BECOMING MORE AMPLIFIED THIS WILL RE-ORIENT PERSISTENT FRONTAL BOUNDARY ACROSS THE OHIO/MISSISSIPPI VALLEYS FROM EAST-WEST TO NORTHWEST-SOUTHEAST AS WESTERN END OF THE FRONT GETS PUSHED NORTH ACROSS IA AND INTO MN/SOUTHERN WI. DRY AIR WILL STILL HANG ON MUCH OF THE DAY...BETTER MOIST INFLOW MAY NOT GET FOCUSED TOWARD LOWER MI UNTIL SUNDAY NIGHT...SO MUCH OF THE DAY SHOULD BE DRY AND MILD WITH PERHAPS JUST A LATE CHANCE FOR PRECIPITATION WEST OF M-37. WILL CARRY THUNDERSTORM CHANCES ALL AREAS FOR SUNDAY NIGHT WITH LOW LEVEL JET FOCUSED ON THE FORECAST AREA. MONDAY RAIN CHANCES STILL LOOK FINE THOUGH MAY END UP BEING MORE OF A MORNING ISSUE. TUESDAY FORECAST PROBABLY A BIT MORE UP IN THE AIR DEPENDING ON WHETHER FRONTAL BOUNDARY PUSHES THROUGH THE STATE OR GETS HUNG UP IF HEIGHT FALLS ARE NOT AS IMPRESSIVE AS INDICATED BY 22/12Z ECMWF OUTPUT. GIVEN THIS CONFLICT SEE NO NEED TO CHANGE CURRENT CHANCE POPS FOR TUESDAY (THOUGH WILL EXPAND TO COVER ALL AREAS). JPB && .APX WATCHES/WARNINGS/ADVISORIES...FLOOD WATCH...THROUGH EARLY SATURDAY MORNING...MIZ041-042. FLOOD WARNING...THROUGH EARLY SATURDAY MORNING...MIZ042. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
257 AM EDT SAT MAR 24 2007 .SHORT TERM (TODAY AND TONIGHT)... OVER THE PAST FEW DAYS...SHORT-RANGE MODELS HAVE BEEN PROGRESSIVELY DIMINISHING OUR PRECIP CHANCES FOR TODAY. RUC13 INITIALIZED WELL WITH RAINFALL AND SFC TEMPS...SO FOLLOWED CLOSE TO THIS FOR POPS AND HIGH TEMPS. CURRENTLY...SFC WARM FRONTAL BOUNDARY IS LOCATED TO OUR NORTH FROM ROUGHLY COLUMBUS OH TO DES MOINES IA. STRONG 500MB RIDGE IS LOCATED ACROSS THE GULF...WITH SFC HIGH PRESSURE DOMINATING THE SERN CONUS. WEAKENING SHORTWAVE MOVING ALONG THE OHIO RIVER IS STILL GENERATING SHOWERS ACROSS OUR INDIANA COUNTIES AS IT MOVES NE AROUND THE RIDGE. THESE SHOWERS WILL CONTINUE TO MOVE NE OUT OF THE CWA...BUT WILL LIKELY CONTINUE ACROSS OUR FAR NERN CWA UNTIL ABOUT SUNRISE. THINK I WILL LEAVE OUT POPS FROM THE GRIDS AND WILL HANDLE RESIDUAL SHOWERS WITH NOWCASTS. SHORT-RANGE MODELS MOVE THE 585DM LINE NORTHWARD ACROSS THE CWA TODAY...WHICH SHOULD SUPPRESS ANY CONVECTION. THUS WILL REMOVE POPS FROM THE GRIDS TODAY THROUGH THE AFTERNOON HOURS. AND BECAUSE OF THIS...WILL INCREASE TEMPS A TAD...TOWARD RUC13 VALUES OF LOW 80S SOUTH TO UPPER 70S NORTH (SIMILAR TO A BLEND OF RAW GFS AND MET GUIDANCE VALUES). THE FRONT TO OUR NORTH IS PROGGED TO SAG A BIT SOUTHWARD TONIGHT...AND ORIENT ITSELF FROM NW TO SE...VERY CLOSE TO OUR NERN CWA BORDER. MOS POPS AT LEX RANGE FROM 20-50 PERCENT. REALLY THINK ANY ACTIVITY WOULD BE TO OUR NE...BUT WITH THE BOUNDARY SO CLOSE WILL INSERT A SLT CHC POP ACROSS THE FAR NERN CWA...MAINLY NE OF A SALEM IN TO WINCHESTER KY LINE AFTER 21Z. WILL END SHORTLY AFTER MIDNIGHT WITH THE LOSS OF HEATING. WENT SLIGHTLY BELOW RUC TEMPS FOR OVERNIGHT LOWS...WITH UPPER 50S NNE...TO MID-TO-LOW 50S DOWN SOUTH WHERE CLOUDS WILL BE LESS. AL .LONG TERM (SUNDAY THROUGH FRIDAY)... SUNDAY THROUGH MONDAY NIGHT... ANOMALOUS RIDGING MORE TYPICAL OF LATE MAY WILL BE CENTERED ACROSS THE LOWER OHIO VALLEY SUNDAY AND MONDAY. 500MB HEIGHTS WILL AVERAGE OVER 5820M ACROSS OUR CWA...WHICH IS AROUND 2.5 STANDARD DEVIATIONS ABOVE NORMAL FOR LATE MARCH. AFTERNOON TEMPERATURES...WHILE NOT SETTING RECORD HIGHS...WILL APPROACH THEM. IF AMPLE SUN IS AVAILABLE SUNDAY AND MONDAY...HIGHS IN THE LOWER 80S ARE LIKELY. THIS RIDGING WILL CORRESPOND TO TROUGHING OUT WEST. ON SUNDAY...ONE UPPER DISTURBANCE WILL BE EJECTING NORTHEASTWARD OUT OF THE MEAN TROUGH CENTERED OVER THE ROCKIES AND WILL MOVE ACROSS THE UPPER MIDWEST. THE MAIN WESTERN TROUGH WILL HANG BACK OVER THE DESERT SOUTHWEST...AND WILL HAVE TO WAIT UNTIL EARLY TUESDAY TO MOVE EAST INTO THE SOUTHERN PLAINS. THE GFS 925MB FORECAST TEMPERATURES 17C SUNDAY AFTERNOON 18C MONDAY AFTERNOON 15C TUESDAY AFTERNOON GIVEN GOOD INSOLATION...MONDAY MAY HAVE THE WARMEST TEMPERATURES OF ALL. WITH RIDGING EXTENDING FROM THE GULF STATES ALL THE WAY TO THE GREAT LAKES...FEEL THAT BOTH SUNDAY AND MONDAY WILL BE DRY. FORECAST SOUNDINGS SHOW NO INSTABILITY SUNDAY WITH SOMEWHAT MORE UNSTABLE CONDITIONS MONDAY. HOWEVER...WITH NO NOTICEABLE TRIGGER MONDAY...WILL REMOVE POPS. TUESDAY THROUGH WEDNESDAY... A POWERFUL AND DEEP TROUGH MOVING ONTO THE WEST COAST LATE MONDAY WILL SERVE TO KICK OUT THE AFOREMENTIONED UPPER LOW ACROSS THE SOUTHERN ROCKIES INTO THE PLAINS ON TUESDAY. THIS OPEN TROUGH SHOULD WEAKEN AS IT IMPINGES UPON THE STRONG RIDGE ACROSS THE SOUTHEASTERN STATES...AND IS FORECAST TO CROSS OKLAHOMA BY BOTH THE NAM AND THE GFS TUESDAY. DEEP SOUTHERLY FLOW AND PRECIPITABLE WATER WILL INCREASE TUESDAY AND WEDNESDAY ACROSS THE LOWER OHIO VALLEY AHEAD OF THIS TROUGH AND WILL CONTINUE CHANCE WORDING FOR POPS TUESDAY AND ADD CHANCE POPS WEDNESDAY. EXPECT WELL ABOVE NORMAL TEMPERATURES TO CONTINUE THROUGH AT LEAST THURSDAY...ALTHOUGH SLIGHTLY REDUCED TUESDAY AND WEDNESDAY DUE TO ADDITIONAL CLOUD COVER. THURSDAY AND FRIDAY... TROUGHING WILL BECOME WELL ESTABLISHED ACROSS THE ROCKIES AS STRONG LOW PRESSURE MOVES NORTH ACROSS THE CENTRAL PLAINS THURSDAY. A COLD FRONT IS EXPECTED TO MOVE EAST ACROSS THE SOUTHERN PLAINS THURSDAY AND PERHAPS ACROSS THE MISSISSIPPI RIVER FRIDAY. WITH OUR FORECAST AREA STILL UNDER RIDGING...WARM TEMPERATURES AND A CHANCE OF AFTERNOON CONVECTION WILL CONTINUE THROUGH FRIDAY. JSD .AVIATION (06Z TAFS)... WITH UPPER RIDGE MOVING FURTHER NORTH...THINK THAT PRECIP CHANCES WILL BE SLIM ACROSS THE AREA THROUGH THE TAF PERIOD...AND ALL SITES SHOULD REMAIN VFR. SCATTERED MID-LEVEL CLOUDINESS IS POSSIBLE AT LEX AND SDF FROM CURRENT HOUR THROUGH MOST OF THE TAF PERIOD. JUST A FEW HIGH CLOUDS EXPECTED IN BWG`S VICINITY. IN THE 18-24 HOUR TIME FRAME...THE WARM FRONT THAT IS CURRENTLY TO OUR NORTH IS PROGGED TO SAG SOUTHWARD AND ORIENT ITSELF IN A NW TO SE FASHION THIS EVENING...COMING CLOSE TO THE LEX TAF SITE. STEEP LOW-LEVEL LAPSE RATES MAY BE INDICATIVE OF AN ISLD SHRA WITH THIS BOUNDARY...HOWEVER WILL NOT INCLUDE IN TAF AT THIS TIME. MAY BEEF UP CLOUD COVER AT LEX AFTER 21Z. EXPECTING TO BE CAPPED JUST ENOUGH THAT PRECIP WOULD STAY NE OF THE SDF AND LEX TAF SITES. WILL REMOVE LOW-LEVEL WIND SHEAR FROM TAFS BASED ON VWPS FROM REGIONAL RADARS AND MOST RECENT SDF ACARS SOUNDING. THE CURRENT AND FORECAST 1-2KFT WINDS ARE ONLY ABOUT 20-25 KTS...AND WITH SFC WINDS AT LEAST 5 KTS...LLWS CRITERIA IS NOT MET AND SHOULD NOT BE MET THROUGH THE TAF PERIOD. MAY BE A BIT GUSTY FROM 15-22Z AT SDF AND LEX...PERHAPS UP TO 15 KTS OR SO...BUT NOTHING OUT OF HAND. AL && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
117 AM EDT SAT MAR 24 2007 .AVIATION (06Z TAFS)... WITH UPPER RIDGE MOVING FURTHER NORTH...THINK THAT PRECIP CHANCES WILL BE SLIM ACROSS THE AREA THROUGH THE TAF PERIOD...AND ALL SITES SHOULD REMAIN VFR. SCATTERED MID-LEVEL CLOUDINESS IS POSSIBLE AT LEX AND SDF FROM CURRENT HOUR THROUGH MOST OF THE TAF PERIOD. JUST A FEW HIGH CLOUDS EXPECTED IN BWG`S VICINITY. IN THE 18-24 HOUR TIME FRAME...THE WARM FRONT THAT IS CURRENTLY TO OUR NORTH IS PROGGED TO SAG SOUTHWARD AND ORIENT ITSELF IN A NW TO SE FASHION THIS EVENING...COMING CLOSE TO THE LEX TAF SITE. STEEP LOW-LEVEL LAPSE RATES MAY BE INDICATIVE OF AN ISLD SHRA WITH THIS BOUNDARY...HOWEVER WILL NOT INCLUDE IN TAF AT THIS TIME. MAY BEEF UP CLOUD COVER AT LEX AFTER 21Z. EXPECTING TO BE CAPPED JUST ENOUGH THAT PRECIP WOULD STAY NE OF THE SDF AND LEX TAF SITES. WILL REMOVE LOW-LEVEL WIND SHEAR FROM TAFS BASED ON VWPS FROM REGIONAL RADARS AND MOST RECENT SDF ACARS SOUNDING. THE CURRENT AND FORECAST 1-2KFT WINDS ARE ONLY ABOUT 20-25 KTS...AND WITH SFC WINDS AT LEAST 5 KTS...LLWS CRITERIA IS NOT MET AND SHOULD NOT BE MET THROUGH THE TAF PERIOD. MAY BE A BIT GUSTY FROM 15-22Z AT SDF AND LEX...PERHAPS UP TO 15 KTS OR SO...BUT NOTHING OUT OF HAND. AL && .PREV DISCUSSION... EVENING UPDATE... WEAKENING IMPULSE MOVING FROM MO INTO SOUTH CENTRAL IL AND SOUTHERN IN ALONG THE PERIPHERY OF THE STRONG 587 H500 RIDGE CENTERED NEAR THE DESTIN FLA COASTLINE. SCATTERED SHOWER ACTIVITY SHOULD REACH THE SOUTHERN INDIANA AND NORTH CENTRAL COUNTIES WEST OF INTERSTATE 65 BEFORE LOSING COVERAGE AS IT MOVES TOWARDS INTERSTATE 75 AND THE LEXINGTON METRO AREA. THEREFORE WILL RAISE POPS IN THE NORTHWESTERN THIRD OF THE FORECAST AREA FROM SCOTTSBURG INDIANA SOUTHWEST TO HAWESVILLE KENTUCKY. WILL MAKE TWEAKS TO CLOUDS TO CATCH CURRENT TRENDS...WILL ADJUST LOWER ACROSS THE SOUTH WHERE FEW TO SCT MID LVL CLOUDS ARE BEING FOUND...SMALL UPWARD TWEAK OF ABOUT 2 DEGREES LOOKS NEEDED FOR OVERNIGHT LOWS WITH DEWPOINTS IN THE MID AND UPPER 50S AND SOME CLOUDS IT WILL BE HARD FOR MUCH OF THE AREA TO DROP MUCH BELOW 60...MORE THAN 20 DEGREES ABOVE THE NORMAL LOW AND NEAR OR JUST ABOVE THE NORMAL HIGHS FOR THE DAY!. SCHOTT SHORT TERM (TNGT AND SAT)... MAY-LIKE TEMPS IN MAR WITH FRONT FROM IND TO SRN OH ATTM TO STAY WELL TO OUR NORTH. WEAKENING AREA OF SHOWERS TO AFFECT MAINLY THE NRN HALF OF OUR FA LATE THIS AFTN...THESE AHD OF UPR IMPLSE RIDING EWD ON SRN EDGE OF WESTERLIES. WOULD ONLY EXPECT ABOUT .10 OF AN INCH OVER OUR SRN INDIANA COUNTIES BY 00Z THIS EVE WITH LIGHTER AMOUNTS SOUTHWARD TO NEAR THE OHIO RIVER ACRS NCNTRL KY AND THE NRN BLUEGRASS REGION. A SECOND IMPLSE COMING NEWD IN DIFFLUENT FLO...ATTM ACRS ERN OK... IS SPAWNING A NEW MCS ACRS SERN KS/MO. THIS IMPLSE FCST TO TAKE A SIMILAR PATH AS THE AFOREMENTIONED ONE...WHILE WEAKENING. WILL THEREFORE KEEP CHC POPS IN THE FCST TNGT...HIEST N-LOWEST S WITH NO POPS ACRS SCNTRL KY. ONE LAST IMPLSE TOPS THE RIDGE SAT AS IT MOVES FROM NEAR STL TO NEAR LOU BY SUN EVE. GFS FCST A BIT MORE UNSTABLE AMS(LIFTED INDICES NEAR -2)AHD OF THIS FEATURE...WILL LEAVE THUNDER IN THE FCST AND SIMILAR CHC POPS TO GOING FCST...AGAIN HIEST ACRS OUR NRN MOST FA. WITH BUILDING RIDGE...AND ONLY MID/HIGH CLDS ACRS OUR SRN FA SAT...CANT ARGUE AGAINST MAX TEMPS ARND 80...WITH TEMPS TEMPERED A BIT NRN FA BY LOWER CLDS AND SCT SHOWERS/STMS. DK LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... SATURDAY NIGHT THROUGH MONDAY NIGHT... HIGHLY AMPLIFIED UPPER AIR PATTERN IS FORECAST ACROSS NORTH AMERICA DURING THIS TIME PERIOD. LARGE UPPER LOW OVER THE SOUTHWEST UNITED STATES IS FORECAST TO LIFT NORTHEASTWARD INTO THE UPPER PLAINS AS LARGE H5 RIDGE HOLDS SWAY ACROSS THE EASTERN THIRD OF THE US. BY LATE IN THIS TIME PERIOD...00Z GFS ENSEMBLE MEANS SHOW DEEPENING H5 TROF COMING INTO THE WESTERN CONUS WHICH WILL HELP KICK OR FLATTEN THE EAST COAST RIDGE SOMEWHAT. AT THE SFC...SFC WARM FRONTAL BOUNDARY WILL BE TO OUR NORTH AND REMAIN THERE THROUGH THIS PORTION OF THE FCST PERIOD. SEVERAL WEAK VORTS WILL LIKELY CRUISE THROUGH WITHIN THE MEAN FLOW AND AROUND THE H5 RIDGE. THE GFS SOLUTIONS KEEP MUCH OF THE PRECIP NORTH OF HERE...WHILE THE NAM-WRF SOLUTIONS AREA BIT FURTHER SOUTH. WITH NO REAL FORCING MECHANISM...DO NOT SEE MUCH OF A CHANCE OF MEASURABLE PRECIPITATION THROUGH MONDAY MORNING. BY MONDAY...WITH FLATTENING RIDGE AND A SFC HIGH TO OUR EAST...GOOD FLOW OF WARM MOIST AIR WILL PUSH IN AND DIURNAL CONVECTION SHOULD GET GOING BY THE AFTERNOON. FOR NOW WILL KEEP LOW CHANCE POPS IN THE FCST. TEMPERATURES THROUGH THE PERIOD WILL BE WAY ABOVE NORMAL...FEELING LIKE LATE MAY OR EARLY JUNE. STUCK CLOSE TO THE ENSEMBLE MEANS FOR TEMPERATURES WITH OVERNIGHT LOWS IN THE MID AND UPPER 50S. HIGHS IN THE UPPER 70S TO AROUND 80 IN THE NORTH FOR SUNDAY LOOK LIKE A GOOD BET...WITH LOWER 80S ACROSS THE CENTRAL AND SOUTHERN TIERS. WITH MORE CLOUDS AND POSSIBLE CONVECTION IN THE AREA MONDAY...TEMPERATURES SHOULD BE A LITTLE COOLER...BUT WILL STILL BE SOME 10-15 DEGREES ABOVE AVERAGE WITH HIGHS IN THE UPPER 70S. TUESDAY THROUGH FRIDAY... MAIN FORECAST CHALLENGE HERE WILL BE POP CHANCES. GIVEN THAT THE PATTERN LOOKS LIKE ONE OF LATE MAY TO EARLY JUNE...DIURNALLY DRIVEN CONVECTION APPEARS TO BE THE MAIN WEATHER MAKER THROUGH THURSDAY. FOR NOW WILL KEEP LOW CHC POPS IN THE AFTERNOON AND EARLY EVENING HOURS. BY THURSDAY...UPPER AIR PATTERN IS FORECAST TO BECOME MORE ZONAL WITH TIME AS STRONG MID-LAT CYCLONE DEVELOPS AND HEADS NE INTO THE SOUTHERN CANADA. ASSOCIATED SFC COLD FRONT IS PROGGED TO PUSH INTO THE REGION LATE THU AND DURING THE DAY ON FRIDAY WHICH WILL BRING A PERIOD OF WIDESPREAD RAIN AND STORMS TO THE AREA. WHILE MAIN FORCING WILL BE NORTH OF THE REGION...OVERALL PATTERN LOOKS INTERESTING FOR A ROUND OF CONVECTIVE WEATHER. SOMETHING TO WATCH OVER THE NEXT FEW DAYS. WARM WEATHER IS EXPECTED TO CONTINUE THROUGH THE PERIOD. STRONG SOUTHERLY FLOW WILL KEEP TEMPERATURES RATHER WARM THROUGH THE PERIOD WITH HIGHS IN THE MID TO UPPER 70S AND OVERNIGHT LOWS IN THE LOW TO MID 50S. THIS IS FAIRLY CLOSE TO THE LATEST ENSEMBLE MEANS AND THE ONGOING FORECAST...SO ONLY SOME MINOR ADJUSTMENTS WILL WERE NEEDED. -MJ && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
347 AM EDT SAT MAR 24 2007 .DISCUSSION...WESTERN GREAT LAKES BENEATH CONFLUENCE ZONE WHERE UPSTREAM SPLIT FLOW MERGING BACK TOGETHER. NORTHERN BRANCH WAVE ALONG U.S./CANADIAN BORDER WILL SWING THROUGH THE STATE TODAY... WHILE SOUTHERN BRANCH UPPER LOW OVER NORTHERN MEXICO BEGINS TO LIFT OUT THROUGH THE PLAINS STATES AND WILL EVENTUALLY HAVE AN IMPACT ON NORTHERN MI WEATHER DURING THE LATTER PORTION OF THE WEEKEND AND INTO EARLY NEXT WEEK. IN GENERAL HOWEVER A RATHER MILD PERIOD SHAPING UP OVER THE NEXT WEEK. MAIN FORECAST CONCERNS WILL DEAL WITH NUISANCE PRECIPITATION AND CLOUD COVER ISSUES TODAY... THEN EVOLUTION OF RAIN CHANCES FOR LATER SUNDAY AND BEYOND AS REMNANTS OF SOUTHERN BRANCH WAVE GET INTO THE ACT. TODAY/TONIGHT...COUPLE OF FEATURES OF NOTE TO START OUT THE FORECAST THIS MORNING. LOW/MID CLOUD HAS BEEN ADVANCING NORTHWARD ACROSS THE LOWER PENINSULA IN AN AREA OF LOW/MID LEVEL WARM ADVECTION NORTH OF STATIONARY FRONTAL BOUNDARY WHICH LIES ACROSS IA/IL/SOUTHERN OH. VARIOUS AIRCRAFT SOUNDINGS ACROSS SOUTHERN LOWER/WI INDICATE MOISTURE LAYER EXTENDS TO ABOUT 600MB...A FAIR AMOUNT DEEPER THAN EXPECTED WHICH HAS BEEN ENOUGH TO ALLOW FOR SCATTERED SHOWERS TO DEVELOP GENERALLY SOUTH OF M-72. TO THE NORTHWEST...WATER VAPOR IMAGERY SHOWS A SHORT WAVE TROUGH ALONG THE MN/ONTARIO BORDER. GOOD DEAL OF MID/HIGH CLOUD WITH THIS FEATURE ADVANCING ACROSS FAR NORTHERN WI/WESTERN UPPER...SOME RADAR RETURNS WITH THIS BUT LITTLE REACHING THE GROUND AS LOWER LAYERS QUITE A BIT DRIER IN 00Z INL/MPX SOUNDINGS. DEALING WITH THE LOWER PENINSULA SHOWER ACTIVITY FIRST...LOOKS LIKE THIS WILL MAINLY BE AN EARLY MORNING ISSUE...IR/RADAR TRENDS SUGGEST THAT BY PRESS TIME SHOULD BE ABLE TO CONFINE EARLY POPS EAST OF US-131/SOUTH OF M-68. ANTICIPATE SHOWER ACTIVITY TO BE EAST OF THE FORECAST AREA BY 15Z. AS FOR THE NORTHERN STREAM SHORT WAVE...CURRENT FORECAST HAS SOME MORNING RAIN CHANCES ACROSS EASTERN UPPER AND THE STRAITS...AND SEE NO REASON NOT TO KEEP THIS GOING. NOT MUCH GOING ON UPSTREAM AS FAR AS SURFACE REPORTS OF PRECIPITATION ARE CONCERNED THOUGH LOW LEVELS AS MENTIONED EARLIER ARE QUITE A BIT DRIER. IR/FOG IMAGERY SHOWS LOW LEVEL MOISTURE SURGING NORTH ACROSS NORTHERN LAKE MICHIGAN AND TOWARD EASTERN UPPER...AND THIS SHOULD AID CHANCES OF SOME LIGHT PRECIP REACHING THE GROUND LATER THIS MORNING AS THE UPPER DYNAMICS ROLL THROUGH. PRECIP CHANCES SHOULD END ACROSS EASTERN UPPER BY EARLY AFTERNOON AS SHORT WAVE PASSES BY AND DRIER AIR SWEEPS IN FROM THE WEST. SO ANTICIPATE DECREASING CLOUDINESS AS THE AFTERNOON WEARS ON ACROSS THE ENTIRE AREA. SOME LAKE BREEZE COMPONENT TO THE WIND FIELDS EXPECTED THIS AFTERNOON...ESPECIALLY ALONG THE LAKE HURON SHORELINE NORTH OF APN AND AROUND THE EASTERN END OF THE UPPER PENINSULA. QUIET NIGHT LOOKS TO BE IN STORE FOR TONIGHT...PERHAPS A LITTLE PATCHY FOG DEVELOPING BEFORE WINDS PICK UP AFTER MIDNIGHT...AND EXPECTING AN INCREASE IN HIGH CLOUDS OVERNIGHT AS WELL. AS FOR ONGOING HYDRO ISSUES...WILL DROP FLOOD WATCHES AT FORECAST ISSUANCE TIME...AND LET ARENAC COUNTY FLOOD WARNING STAND ON ITS OWN. SOUTH BRANCH TOBACCO/RIFLE RIVERS HAVE CRESTED AND ARE ON THEIR WAY DOWN. SUNDAY...FORECAST FOR SUNDAY CONTINUES TO OSCILLATE BACK AND FORTH AS TO WHETHER OR NOT ANY PRECIPITATION IS GOING TO MAKE IT INTO THE AREA DURING THE DAYTIME. GUIDANCE IS TRENDING BACK TOWARD TRYING TO PUSH AT LEAST SOME REMNANT WARM ADVECTION PRECIP ACROSS THE STATE FROM THE SOUTH SUNDAY...MAIN MODEL DISCREPANCY APPEARS TO BE IN TIMING OF BETTER LOW LEVEL MOISTURE RETURN (GFS/UKMET QUICKER...NAM SLOWER). CURRENT FORECAST HAS AFTERNOON RAIN CHANCES ACROSS FAR SOUTHWEST PORTION OF THE FORECAST AREA AND THIS STILL LOOKS FINE...WILL ACKNOWLEDGE GUIDANCE TREND AND EXPAND PRECIP CHANCES A LITTLE FARTHER INLAND DURING THE AFTERNOON...KEEPING MAINLY NORTHEAST LOWER DRY UNTIL SUNDAY EVENING. MAIN AREA OF CONVECTION WILL BE DEVELOPING ALONG FRONTAL BOUNDARY AND AHEAD OF SHORT WAVE TROUGH ACROSS MN/WI/IA/IL...WHICH WILL ALL LIFT EAST/ NORTHEAST AND SPREAD ACROSS THE FORECAST AREA AFTER MIDNIGHT ALONG NOSE OF 40+KT LOW LEVEL JET. MONDAY THROUGH WEDNESDAY...SHORT WAVE ENERGY AND ASSOCIATED CONVECTION WILL ROLL THROUGH NORTHERN MI MONDAY MORNING...STILL LOOKS LIKE IT MAY DRY OUT DURING THE AFTERNOON. MONDAY NIGHT LOOKING A LITTLE MORE INTERESTING FROM THE STANDPOINT THAT IT MAY END UP BEING CLOUDY BUT DRY AS SURFACE BOUNDARY PRESSES IN FROM THE NORTH. NO REAL INSTABILITY APPEARS TO BE IN THE CARDS THOUGH SIGNS OF SOME TRAPPED LOW LEVEL MOISTURE COULD END UP WITH SOME FOG/DRIZZLE MORE THAN ANYTHING ELSE. HOW FAR SOUTH THE BOUNDARY GETS WILL THEN IMPACT POTENTIAL RAIN CHANCES FOR THE MIDWEEK PERIOD AS LEE CYCLOGENESIS LOOKS TO GET RAMPED UP BY WEDNESDAY... THE END RESULT MAY BE ANOTHER SURGE OF WARM ADVECTION PRECIP INTO THE STATE LATER TUESDAY INTO WEDNESDAY THOUGH INITIAL SURGE OF RAIN MAY BE BLUNTED BY DRY EASTERLY FLOW AROUND HUDSON BAY SURFACE HIGH. A LOT OF UNCERTAINTY REGARDING THIS HOWEVER...WHICH ARGUES FOR FEW CHANGES TO GOING FORECAST AND THAT SEEMS TO BE THE CONSENSUS. WILL GO DRY ACROSS EASTERN UPPER FOR TUESDAY...WITH LOW CHANCE POPS ACROSS NORTHERN LOWER. WILL KEEP WEDNESDAY DRY FOR NOW...IT MAY TURN OUT THAT THE TUESDAY/WEDNESDAY FORECASTS WILL NEED TO BE SWAPPED (DRY TUESDAY/RAIN WEDNESDAY). && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ JPB
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
830 AM PDT SAT MAR 24 2007 .SHORT TERM (TODAY-MONDAY)...MARINE LAYER HAS DEEPENED RAPIDLY THIS MORNING ACROSS THE LA BASIN...WITH PILOT REPORTS AND ACARS DATA INDICATING A DEPTH AROUND 4000 FEET. AS A RESULT...LOW CLOUDS AND FOG HAVE SURGED WELL INTO THE SANTA CLARITA VALLEY AND LOWER COASTAL SLOPES DURING THE PAST FEW HOURS. THE BIG QUESTION MARK TODAY WILL BE THE AMOUNT OF STRATUS BURNOFF. THERE MAY BE SOME DIFFICULTY IN CLEARING ACROSS SOME AREAS TODAY...SO PARTLY CLOUDY OR PARTIAL AFTERNOON CLEARING WORDING HAS BEEN MENTIONED IN CURRENT ZONE PACKAGE. WITH THE DEEPENING MARINE LAYER...WILL SEE A SIGNIFICANT DROP IN TEMPERATURES TODAY ACROSS MOST AREAS...WITH MOST COASTAL AND VALLEY AREAS REMAINING IN THE 60S. THE ANTELOPE VALLEY WILL CONTINUE TO SEE WARM TEMPERATURES WELL INTO THE 70S. *** FROM PREVIOUS DISCUSSION *** WEAK RIDGING WILL REMAIN IN PLACE THROUGH AT LEAST SUNDAY AFTERNOON AS DEVELOPING TROUGH IN THE GULF OF ALASKA PUSHES DOWN TO THE WEST COAST. MODELS STILL ARE STRUGGLING WITH MODELING THE TROUGHS INTENSITY SOME. POPS AND WEATHER HAVE BEEN CHANGED VERY LITTLE AS THIS SERIES OF MODEL RUNS HAS BACKED OFF THE TROUGHS STRENGTH. THE TROUGH TILT...WHICH THE ALL MODELS INDICATED A FAIR AMOUNT OF IN PREVIOUS RUNS...IS PRETTY MUCH NON-EXISTENT. IN ADDITION TO THE TROUGH BEING VERTICALLY STACKED...LATEST 850 MB TEMPERATURE PATTERN INDICATES LITTLE PRESENCE OF WARM AIR ADVECTION OCCURRING AHEAD OF THE TROUGHS FRONTAL BOUNDARY. TIMING APPEARS TO BE PRETTY CONSISTENT AMONGST ALL MODEL SOLUTIONS THOUGH...WITH PRECIPITATION ARRIVING ALONG THE CENTRAL COAST MONDAY AFTERNOON OR EVENING. .LONG TERM (TUESDAY-FRIDAY)...PRECIPITATION THREAT SHOULD SHIFT SOUTHWARD INTO THE SOUTHLAND LATE MONDAY NIGHT OR INTO TUESDAY MORNING. COLD AIR ARRIVES RAPIDLY BEHIND THE FRONTAL BOUNDARY...WITH 500 MB AND 700 MB TEMPERATURES DROPPING RAPIDLY. CONVECTIVE SHOWERS AND THUNDERSTORMS SHOULD OCCUR BEHIND IN THE COLD AIR SECTOR AS 500 MB TEMPERATURES DROP BELOW -25 CELSIUS ON TUESDAY MORNING. TREND MAY ALSO INDICATE THAT PRECIPITATION WITH THIS STORM SYSTEM MAY VERY LIKELY BE MORE SHOWERY THAN STRATIFORM. CLEARING SHOULD COMMENCE ON TUESDAY AFTERNOON AND TUESDAY NIGHT AS UPPER-LEVEL PATTERN SETS UP FOR A SERIES OF OFFSHORE FLOW EVENTS FOR MIDWEEK. GFS INDICATES RATHER MODERATE EVENTS AT THE CURRENT TIMES...WITH ADVISORY LEVEL WINDS LIKELY OCCURRING. AMPLE THERMAL AND PRESSURE GRADIENTS DEVELOP TUESDAY AFTERNOON INTO AT LEAST THURSDAY MORNING FOR OFFSHORE WINDS. MUCH DIVERGENCE OCCURS AS FAR AS WHAT MAY HAPPEN FOR LATE NEXT WEEK. GFS AND ECMWF CONTINUE TO INDICATE GENERAL RIDGE PATTERN CONTINUING BUT SOME MODEL RUNS ARE CARVING A TROUGH THROUGH THE RIDGE PATTERN. FORECAST KEEPS RIDING PATTERN IN PLACE FOR NOW. && .AVIATION...24/0900Z...ONSHORE FLOW WILL PERSIST TODAY AS LOW CLOUDS WITH MVFR CIGS TO THE SOUTH AND IFR CIGS N OF POINT CONCEPTION WILL CONTINUE THROUGH THE MID MORNING HOURS IN THE VALLEYS TO THE EARLY AFTERNOON HOURS ACROSS THE COASTAL PLAIN WITH ONLY PARTIAL CLEARING NEAR THE IMMEDIATE COAST TODAY. VSBYS THIS MORNING GENERALLY VFR/MVFR IN MOST AREAS. LOOKS LIKE KPRB WILL NOW STAY CLEAR THIS MORNING AS DEWPOINT DEPRESSION IS FAR ENOUGH APART NOT TO WARRANT ANY STRATUS AND DENSE FOG ISSUES. EXPECT GUSTY SOUTHWEST TO WEST WINDS ACROSS THE ANTELOPE VALLEY TODAY. KLAX WILL EXPERIENCE MVFR CIGS THROUGH EARLY AFTERNOON HOURS...WITH STUBBORN CLEARING ALONG THE IMMEDIATE COAST. EXPECT SE WINDS BELOW 6 KT THROUGH 12Z...BECOMING VARIABLE 6 KT OR LESS. SOUTHWEST SEABREEZE SHOULD PICK UP NEAR 18Z AND BECOME WESTERLY THIS AFTERNOON. WINDS SHOULD BE SUSTAINED NEAR 12 KT THIS AFTERNOON THROUGH EARLY EVENING HOURS. KBUR WILL HAVE MVFR CIGS THIS MORNING. CIGS SHOULD BURN OFF BY 17-18Z THIS MORNING. NOT EXPECTING LIFR/IFR VSBYS WITH DEEPER MARINE LAYER IN PLACE. NOT EXPECTING ANY UNTYPICAL WIND ISSUES TODAY. && .MARINE...A RELATIVELY LARGE WESTERLY SWELL WILL IMPACT THE CENTRAL COAST BY TUESDAY WITH SWELLS FORECAST TO REACH 14 FEET ACROSS THE OUTER WATERS. THE SANTA BARBARA CHANNEL INNER WATERS WILL ALSO SEE POTENTIAL SWELLS UP TO 10 FEET TUESDAY NIGHT THROUGH EARLY WEDNESDAY MORNING. THE COMBINATION OF THIS LARGE SWELL...GUSTY WINDS AND POSSIBLE THUNDER SHOULD MAKE FOR POTENTIALLY ROUGH SEAS FROM LATE MONDAY NIGHT THROUGH EARLY WEDNESDAY. MARINERS SHOULD KEEP ABREAST OF THIS DEVELOPING SITUATION FOR EARLY NEXT WEEK. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PACIFIC COASTAL WATERS... SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS (SEE LAXCWFLOX). && $$ PUBLIC...GOMBERG/HALL AVIATION/MARINE...KAPLAN WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
400 AM PDT SAT MAR 24 2007 .SYNOPSIS... HIGH PRESSURE WILL BUILD OVER SOUTHERN CALIFORNIA THIS WEEKEND BRINGING FAIR AND DRY WEATHER WITH WARMER TEMPERATURES FOR INLAND AREAS. THE MARINE LAYER WILL KEEP COASTAL AREAS COOLER WITH NIGHT AND MORNING LOW CLOUDS AND FOG. A FAST MOVING PACIFIC STORM SYSTEM WILL MOVE THROUGH CALIFORNIA TUESDAY BRINGING COOLING...STRONG GUSTY WINDS IN THE MOUNTAINS AND DESERTS...AND A CHANCE OF SHOWERS. FAIR WITH A WARMING TREND FOR THE LATTER HALF OF NEXT WEEK AS BROAD HIGH PRESSURE BUILDS INTO CALIFORNIA. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (TODAY THROUGH MONDAY)... HIGH PRESSURE WILL BUILD OVER SOUTHERN CALIFORNIA THROUGH SUNDAY... THEN BEGIN TO WEAKEN MONDAY. THIS WILL BRING FAIR AND DRY WEATHER WITH WARMER TEMPERATURES FOR INLAND AREAS THROUGH SUNDAY...THEN SLOW COOLING MONDAY. WEST OF THE MOUNTAINS...THE MARINE LAYER WILL KEEP TEMPERATURES NEAR SEASONAL LEVELS WITH NIGHT AND MORNING LOW CLOUDS AND FOG. CURRENT ACARS SOUNDINGS SHOW A WEAKENING MARINE INVERSION NEAR 5000 FEET WITH A SECOND INVERSION DEVELOPING AND STRENGTHENING BETWEEN 2500 AND 3000 FEET. THIS LOWER INVERSION SHOULD BECOME THE DOMINANT INVERSION THE NEXT COUPLE OF DAYS...LOWERING AND STRENGTHENING SOME THROUGH SUNDAY AS HIGH PRESSURE STRENGTHENS ALOFT. THE MARINE LAYER SHOULD BEGIN TO DEEPEN SOME MONDAY AS HIGH PRESSURE BEGINS TO WEAKEN. && .LONG TERM (TUESDAY THROUGH FRIDAY)... FOR TUESDAY...STILL DECENT AGREEMENT AMONG THE MODELS ON A FAST MOVING PACIFIC STORM SYSTEM THAT WILL MOVE THROUGH CALIFORNIA. FOR SOUTHWEST CALIFORNIA...THIS WILL BRING COOLING...STRONG GUSTY WINDS IN THE MOUNTAINS AND DESERTS...A MUCH DEEPER MARINE LAYER MONDAY NIGHT AND TUESDAY...AND A CHANCE OF SHOWERS LATE MONDAY NIGHT THROUGH TUESDAY. FOR THE LATTER HALF OF NEXT WEEK...BROAD HIGH PRESSURE BUILDS OVER CALIFORNIA. THIS WILL BRING FAIR AND DRY WEATHER WITH A STEADY WARMING TREND INTO THE WEEKEND. && .AVIATION... 241040Z...MARINE LAYER WITH A DEEP MOIST LAYER WITH GENERALLY TWO DECKS...ONE WITH BASES ABOUT 2000 FT MSL NEAR THE COAST AND THE OTHER HAS BASES ABOUT 5000 FT MSL INLAND. ALSO SOME STRATUS FILLING IN THE COACHELLA VALLEY WITH BASES ABOUT 5500 FEET MSL. TOPS ABOUT 2500 FT NEAR THE COAST AND LOCAL TOPS UP TO 6000 FT INLAND AND IN THE LOWER DESERTS. VIS VFR WITH LOCAL MVFR AND ISOLD IFR POSSIBLE NEAR THE FOOTHILLS. EXPECT STRATUS TO CLEAR TO THE COAST BY 17Z AND BE MOSTLY OUT OF THE COAST BY 19Z. STRATUS SHOULD SPREAD BACK IN ALONG THE COAST BY 02Z THIS EVENING AND INLAND BEFORE MIDNIGHT. WINDS AT 5K FT...NORTHWEST 10KT EARLY THIS MORNING...BECOMING LIGHT AND VARIABLE LATE THIS MORNING THROUGH SUN MORNING...THEN WEST 5-10 KT SUN AFTERNOON. WINDS AT 10K FT...NORTHWEST TO NORTH 10-15 KT... NORTHEAST 10-15 KT TONIGHT...BECOMING NORTHWEST TO NORTH 10 KT LATE SUN MORNING THROUGH AFTERNOON. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...MARTIN AVIATION/MARINE...WHITLOW NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1005 AM EDT SAT MAR 24 2007 .UPDATE...WATER VAPOR IMAGERY SHOWING RESPECTABLE SHORT WAVE RUNNING ACROSS THE UPPER PENINSULA THIS MORNING...AND ASSOCIATED MID LEVEL DRY PUNCH EXTRAPOLATED TO PASS THROUGH THE CWA THROUGH 16Z OR SO. SCT LIGHT RAIN SHOWERS ASSOCIATED WITH THE WAVE NOW PASSING ACROSS THE NRN THIRD OF THE CWA. MEANWHILE...DEEP LOW LEVEL MOISTURE EXTENDS UP THROUGH LOWER MICHIGAN TO AROUND THE TIP OF THE MITT COUNTIES. EARLIER SHOWER ACTIVITY HAS EXITED...BUT QUITE A BIT OF FOG ACROSS NRN LOWER MICHIGAN AND EVEN SOME DRIZZLE SHOWING UP ACROSS THE HIGHER TERRAIN ON KAPX RADAR. ALSO OF NOTE...MCS ACTIVITY ONGOING ACROSS THE MIDWEST ALONG STATIONARY FRONT BUT EXPECTED TO REMAIN WELL SOUTH OF THE REGION TODAY. FORECAST CONCERNS FOR THE AFTERNOON OBVIOUSLY REVOLVE AROUND ANTICIPATED CLEARING TREND. AS MENTIONED ABOVE...MID LEVEL DRY SLOT EXTRAPOLATED TO PASS THROUGH THE CWA THROUGH 16Z...AT WHICH POINT SHOWER ACTIVITY ACROSS THE NRN THIRD OF THE CWA WILL END...AND WE SHOULD BEGIN TO SEE W-E IMPROVEMENT ACROSS NRN LOWER MICHIGAN AS DAYTIME HEATING/MIXING GOES TO WORK ON REMAINING THINNER LOW LEVEL MOISTURE. AM CONCERNED THE CLEARING PROCESS MAY TAKE AWHILE TO UNFOLD (AS OFTEN TIMES HAPPENS) PARTICULARLY ACROSS NORTHEAST LOWER MICHIGAN AND MAY KEEP THINGS ON THE MOSTLY CLOUDY SIDE THERE THROUGH MID AFTERNOON WITH THE MORNING UPDATE. OTHERWISE...DEPENDING ON THE SPEED AND DEGREE OF CLEARING... TEMPERATURES COULD TOUCH 60 IN SOME SPOTS IN NRN LOWER BUT STRUGGLE TO GET OUT OF THE 40S IN OTHERS (NORTHEAST LOWER) IF CLEARING IS SLOW. PLAN IS TO TWEAK TEMPS DOWN JUST A LITTLE FROM THE CURRENT FORECAST ACROSS NE LOWER MICHIGAN WITH THE IDEA OF A SLOWER CLEARING TREND. HOWEVER...THIS WILL OBVIOUSLY BE THE WRONG DIRECTION IF CLOUD COVER DOES MIX AND CLEAR OUT FASTER. ADAM && .AVIATION...ISSUED AT 746 AM. UPPER LEVEL SHORTWAVE WILL SWEEP ACROSS NORTHERN MICHIGAN LATER THIS MORNING. BUILDING HIGH PRESSURE AND STRONG DRYING BEHIND DEPARTING SYSTEM WILL HELP SCOUR OUT LOW LEVEL MOISTURE AND ASSOCIATED VFR-MVFR CLOUD DECK AND VISIBILITIES BY THIS AFTERNOON. CEILINGS/VIS EXPECTED TO REMAIN UNOBSTRUCTED LATER THIS AFTERNOON THROUGH THE OVERNIGHT AS HIGH PRESSURE REMAINS IN CONTROL. WINDS EXPECTED TO REMAIN UNDER 10 KNOTS ALL TAF SITES THROUGH THIS TAF CYCLE. MSB && .DISCUSSION...ISSUED AT 347 AM. WESTERN GREAT LAKES BENEATH CONFLUENCE ZONE WHERE UPSTREAM SPLIT FLOW MERGING BACK TOGETHER. NORTHERN BRANCH WAVE ALONG U.S./CANADIAN BORDER WILL SWING THROUGH THE STATE TODAY...WHILE SOUTHERN BRANCH UPPER LOW OVER NORTHERN MEXICO BEGINS TO LIFT OUT THROUGH THE PLAINS STATES AND WILL EVENTUALLY HAVE AN IMPACT ON NORTHERN MI WEATHER DURING THE LATTER PORTION OF THE WEEKEND AND INTO EARLY NEXT WEEK. IN GENERAL HOWEVER A RATHER MILD PERIOD SHAPING UP OVER THE NEXT WEEK. MAIN FORECAST CONCERNS WILL DEAL WITH NUISANCE PRECIPITATION AND CLOUD COVER ISSUES TODAY...THEN EVOLUTION OF RAIN CHANCES FOR LATER SUNDAY AND BEYOND AS REMNANTS OF SOUTHERN BRANCH WAVE GET INTO THE ACT. TODAY/TONIGHT...COUPLE OF FEATURES OF NOTE TO START OUT THE FORECAST THIS MORNING. LOW/MID CLOUD HAS BEEN ADVANCING NORTHWARD ACROSS THE LOWER PENINSULA IN AN AREA OF LOW/MID LEVEL WARM ADVECTION NORTH OF STATIONARY FRONTAL BOUNDARY WHICH LIES ACROSS IA/IL/SOUTHERN OH. VARIOUS AIRCRAFT SOUNDINGS ACROSS SOUTHERN LOWER/WI INDICATE MOISTURE LAYER EXTENDS TO ABOUT 600MB...A FAIR AMOUNT DEEPER THAN EXPECTED WHICH HAS BEEN ENOUGH TO ALLOW FOR SCATTERED SHOWERS TO DEVELOP GENERALLY SOUTH OF M-72. TO THE NORTHWEST...WATER VAPOR IMAGERY SHOWS A SHORT WAVE TROUGH ALONG THE MN/ONTARIO BORDER. GOOD DEAL OF MID/HIGH CLOUD WITH THIS FEATURE ADVANCING ACROSS FAR NORTHERN WI/WESTERN UPPER...SOME RADAR RETURNS WITH THIS BUT LITTLE REACHING THE GROUND AS LOWER LAYERS QUITE A BIT DRIER IN 00Z INL/MPX SOUNDINGS. DEALING WITH THE LOWER PENINSULA SHOWER ACTIVITY FIRST...LOOKS LIKE THIS WILL MAINLY BE AN EARLY MORNING ISSUE...IR/RADAR TRENDS SUGGEST THAT BY PRESS TIME SHOULD BE ABLE TO CONFINE EARLY POPS EAST OF US-131/SOUTH OF M-68. ANTICIPATE SHOWER ACTIVITY TO BE EAST OF THE FORECAST AREA BY 15Z. AS FOR THE NORTHERN STREAM SHORT WAVE...CURRENT FORECAST HAS SOME MORNING RAIN CHANCES ACROSS EASTERN UPPER AND THE STRAITS...AND SEE NO REASON NOT TO KEEP THIS GOING. NOT MUCH GOING ON UPSTREAM AS FAR AS SURFACE REPORTS OF PRECIPITATION ARE CONCERNED THOUGH LOW LEVELS AS MENTIONED EARLIER ARE QUITE A BIT DRIER. IR/FOG IMAGERY SHOWS LOW LEVEL MOISTURE SURGING NORTH ACROSS NORTHERN LAKE MICHIGAN AND TOWARD EASTERN UPPER...AND THIS SHOULD AID CHANCES OF SOME LIGHT PRECIP REACHING THE GROUND LATER THIS MORNING AS THE UPPER DYNAMICS ROLL THROUGH. PRECIP CHANCES SHOULD END ACROSS EASTERN UPPER BY EARLY AFTERNOON AS SHORT WAVE PASSES BY AND DRIER AIR SWEEPS IN FROM THE WEST. SO ANTICIPATE DECREASING CLOUDINESS AS THE AFTERNOON WEARS ON ACROSS THE ENTIRE AREA. SOME LAKE BREEZE COMPONENT TO THE WIND FIELDS EXPECTED THIS AFTERNOON...ESPECIALLY ALONG THE LAKE HURON SHORELINE NORTH OF APN AND AROUND THE EASTERN END OF THE UPPER PENINSULA. QUIET NIGHT LOOKS TO BE IN STORE FOR TONIGHT...PERHAPS A LITTLE PATCHY FOG DEVELOPING BEFORE WINDS PICK UP AFTER MIDNIGHT...AND EXPECTING AN INCREASE IN HIGH CLOUDS OVERNIGHT AS WELL. AS FOR ONGOING HYDRO ISSUES...WILL DROP FLOOD WATCHES AT FORECAST ISSUANCE TIME...AND LET ARENAC COUNTY FLOOD WARNING STAND ON ITS OWN. SOUTH BRANCH TOBACCO/RIFLE RIVERS HAVE CRESTED AND ARE ON THEIR WAY DOWN. SUNDAY...FORECAST FOR SUNDAY CONTINUES TO OSCILLATE BACK AND FORTH AS TO WHETHER OR NOT ANY PRECIPITATION IS GOING TO MAKE IT INTO THE AREA DURING THE DAYTIME. GUIDANCE IS TRENDING BACK TOWARD TRYING TO PUSH AT LEAST SOME REMNANT WARM ADVECTION PRECIP ACROSS THE STATE FROM THE SOUTH SUNDAY...MAIN MODEL DISCREPANCY APPEARS TO BE IN TIMING OF BETTER LOW LEVEL MOISTURE RETURN (GFS/UKMET QUICKER...NAM SLOWER). CURRENT FORECAST HAS AFTERNOON RAIN CHANCES ACROSS FAR SOUTHWEST PORTION OF THE FORECAST AREA AND THIS STILL LOOKS FINE...WILL ACKNOWLEDGE GUIDANCE TREND AND EXPAND PRECIP CHANCES A LITTLE FARTHER INLAND DURING THE AFTERNOON...KEEPING MAINLY NORTHEAST LOWER DRY UNTIL SUNDAY EVENING. MAIN AREA OF CONVECTION WILL BE DEVELOPING ALONG FRONTAL BOUNDARY AND AHEAD OF SHORT WAVE TROUGH ACROSS MN/WI/IA/IL...WHICH WILL ALL LIFT EAST/ NORTHEAST AND SPREAD ACROSS THE FORECAST AREA AFTER MIDNIGHT ALONG NOSE OF 40+KT LOW LEVEL JET. MONDAY THROUGH WEDNESDAY...SHORT WAVE ENERGY AND ASSOCIATED CONVECTION WILL ROLL THROUGH NORTHERN MI MONDAY MORNING...STILL LOOKS LIKE IT MAY DRY OUT DURING THE AFTERNOON. MONDAY NIGHT LOOKING A LITTLE MORE INTERESTING FROM THE STANDPOINT THAT IT MAY END UP BEING CLOUDY BUT DRY AS SURFACE BOUNDARY PRESSES IN FROM THE NORTH. NO REAL INSTABILITY APPEARS TO BE IN THE CARDS THOUGH SIGNS OF SOME TRAPPED LOW LEVEL MOISTURE COULD END UP WITH SOME FOG/DRIZZLE MORE THAN ANYTHING ELSE. HOW FAR SOUTH THE BOUNDARY GETS WILL THEN IMPACT POTENTIAL RAIN CHANCES FOR THE MIDWEEK PERIOD AS LEE CYCLOGENESIS LOOKS TO GET RAMPED UP BY WEDNESDAY... THE END RESULT MAY BE ANOTHER SURGE OF WARM ADVECTION PRECIP INTO THE STATE LATER TUESDAY INTO WEDNESDAY THOUGH INITIAL SURGE OF RAIN MAY BE BLUNTED BY DRY EASTERLY FLOW AROUND HUDSON BAY SURFACE HIGH. A LOT OF UNCERTAINTY REGARDING THIS HOWEVER...WHICH ARGUES FOR FEW CHANGES TO GOING FORECAST AND THAT SEEMS TO BE THE CONSENSUS. WILL GO DRY ACROSS EASTERN UPPER FOR TUESDAY...WITH LOW CHANCE POPS ACROSS NORTHERN LOWER. WILL KEEP WEDNESDAY DRY FOR NOW...IT MAY TURN OUT THAT THE TUESDAY/WEDNESDAY FORECASTS WILL NEED TO BE SWAPPED (DRY TUESDAY/RAIN WEDNESDAY). && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ JPB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
925 AM EDT SAT MAR 24 2007 .UPDATE... LIGHT WIND FIELDS HAVE PROMOTED DEVELOPMENT OF AREAS OF DENSE FOG OVR SCNTRL UPR MI LAST NIGHT INTO EARLY THIS MORNING. 10Z TAMDAR FM KSAW INDICATED MOIST PROFILE TO NEAR 900MB WHILE YQT TAMDAR SHOWED DRIER CONDITIONS WITH MOISTURE EXTENDING TO ONLY 975MB. DRY AIR WILL SPILL IN AFTER SHORTWAVE OVR NORTH LAKE SUPERIOR PASSES THROUGH THIS MORNING. WEAK PRES RISE OVR NW WI WILL ALSO EDGE EAST AND SHOULD BEGIN TO SCOUR OUT THE FOG SO DID NOT ISSUE AN ADVY. DID UPDATE GRIDS TO EMPHASIZE FOG MORE. SECOND BATCH OF SHOWERS ALONG SHORTWAVE TROUGH DID PRODUCE SOME RAIN AT KCMX. TIMING THE BACK EDGE OF ENHANCED CLOUDS/RADAR ECHOES HAS THE SHOWERS OUT OF CWA AFTER 16Z. BASED ON MIXING TO H85 ON LATEST RUC SOUNDINGS MAY NEED TO RAISE TEMPS FM CURRENT MAX TEMPS IN GRIDS...ALTHOUGH DEVELOPING LAKE BREEZES WILL EVENTUALLY COOL THE SHORE LINES. && .PREV DISCUSSION (545 AM EDT)... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW NEARLY ZONAL FLOW ACROSS THE NRN CONUS/SRN CANADA. IN THIS FAST FLOW...SHORTWAVE OF INTEREST IN THE SHORT TERM IS OVER SRN SASKATCHEWAN/ERN MT/WRN ND. RADARS SHOW DECENT COVERAGE OF ECHOES ACROSS ND/SRN MANITOBA ASSOCIATED WITH THIS SHORTWAVE...AND THERE HAVE BEEN A FEW OBS THAT HAVE INDICATED -SHRA IN NRN ND/SE SASKATCHEWAN/SRN MANITOBA TODAY. WELL TO THE W... SHORTWAVE THAT DROPPED OUT OF THE WESTERLIES 2-3 DAYS AGO OVER THE W COAST AND BECAME A MID LEVEL LOW IS NOW CENTERED JUST S OF AZ. THIS SYSTEM WILL BE OF INTEREST TO FCST HERE LATE IN THE UPCOMING WEEKEND AS IT GETS KICKED NE BY NEXT TROF APPROACHING THE W COAST. TODAY...WILL KEEP A SLIGHT CHC OF RAIN IN THIS MORNING FOR THE NRN TIER OF THE FCST AREA AS THE SHORTWAVE FROM NRN MN MOVES ACROSS THE FCST AREA. OTHERWISE...MODELS SHOW GOOD DRYING/SUBSIDENCE WITH MID-LVL RDGG IN THE WAKE OF SHORTWAVE SO WOULD EXPECT SKIES TO CLEAR FROM W TO E IN THE AFTERNOON. WITH WEAK SFC HIGH PRES OVER THE AREA...EXPECT LAKE BREEZE FORMATION THIS AFTERNOON NEAR LAKE SUPERIOR AND LAKE MICHIGAN TO KEEP TEMPS COOLER THERE. MIXING TO AROUND 850 MB ON FCST SOUNDINGS SHOULD YIELD HIGHS IN THE UPPER 50S TO LOWER 60S OVER THE WRN INTERIOR. TONIGHT...SFC RDG AND ASSOC VERY DRY AIRMASS IN PLACE OVER THE AREA(PWAT AOB 0.25 INCH) AND LIGHT WINDS SHOULD ALLOW FOR FAVORABLE RADIATIONAL COOLING CONDITIONS INTO THE EARLY OVERNIGHT AS TEMPS DROP INTO THE LOWER 30S PER MOS GUIDANCE. LOOK FOR INCREASING CLOUDS AFTER 06Z HOWEVER AS WINDS BECOME SE ON BACKSIDE OF RDG. HIGHER DWPNTS INTO THE LOW TO MID 30S ADVECTING OVER LAKE MICHIGAN IN A SE FLOW COULD RESULT IN PATCHY FOG FOR CENTRAL AND ERN COUNTIES AFTER MIDNIGHT. SE DOWNSLOPE WINDS LATE FOR FAR WEST COULD BRING TEMPS UP SOME BEFORE SUNRISE. SUN INTO SUN NIGHT...MDLS ARE IN GENERAL AGREEMENT LIFTING A SHRTWV...REMNANTS OF A CLOSED LOW OVER THE SW U.S...INTO THE WRN GREAT LAKES. THE 00Z UKMET IS STILL SLOWER WITH THE SYSTEM THAN THE GFS/CANADIAN AND NAM. GENERALLY FOLLOWED CONSENSUS OF GFS/NAM AND CANADIAN FOR DETAILS. INITIAL SHRA/TSRA COULD DEVELOP BY SUN MORNING OVER WI BDR COUNTIES WITH STRONG WAA AT NOSE OF 30-40 KT 850 MB JET AND PWAT VALUES INCREASING TO GREATER THAN AN INCH. 850 MB THETA-E RDG ALSO MOVES IN FROM THE W ALONG WITH DECREASING 850-500 MB THETA-E LAPSE RATES AND UPR DIFLUENCE AHEAD OF SHORTWAVE TROF. SCT STORMS FORMING IN THE SW FCST AREA IN THE MORNING WILL SPREAD NE ACROSS THE CWFA IN THE AFTERNOON. DEEP Q-VECT CONVERGENCE JUST AHEAD OF THE SHORTWAVE SPREADS ACROSS THE FCST AREA SUN NIGHT SUPPORTING LIKELY POPS ACROSS THE CWFA. ELEVATED CAPE VALUES OF 500-1000 J/KG OFF MODEL SNDGS ALONG WITH DEEP LYR SHEAR IN EXCESS OF 35 KT AND SRH APPROACHING 300 M2/S2 COULD SUPPORT SOME ELEVATED SUPERCELLS. SPC DAY 2 CONVECTIVE OUTLOOK HAS MUCH OF THE WEST AND SCNTRL FCST AREA IN A SLIGHT RISK FOR SVR STORMS. WET-BULB ZERO HEIGHTS IN 7-8 KFT RANGE WOULD ARGUE FOR LARGE HAIL AS THE BIGGEST THREAT ESPECIALLY AS LOW-LEVELS BECOME MORE STABLE BY LATE AFT AND EVENING. BRIEF HEAVY DOWNPOURS WILL BE LIKELY AS WELL BUT SINCE SYSTEM SHOULD BE FAIRLY PROGRESSIVE WOULD NOT EXPECT PCPN AMOUNTS MUCH MORE THAN HALF AN INCH. MON...EXPECT SHRA/TSRA TO END OVER THE WEST EARLY AND E BY AFTERNOON AS THE SHORTWAVE DEPARTS E AND RDGING/QVECTOR DIV BUILD IN BEHIND IT. EXPECTED SUNSHINE WITH WRLY FLOW AND 900 MB TEMPS FCST NEAR 10C SHOULD ALLOW TEMPS TO CLIMB TO LOWER 60S ESPECIALLY OVER WRN FCST AREA. LINGERING SFC TROF...POSSIBLE CLOUDS AND NW FLOW EXPECTED BEHIND THE TROF COULD KEEP ERN COUNTIES IN THE LOWER 50S. MON NIGHT INTO TUE...EXPECT DRY CONDITIONS AS MID-LVL RIDGE STAYS POSITIONED OVER THE REGION. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...JLA PREV DISCUSSION...VOSS
AREA FORECAST DISCUSSION
NWS GAYLORD MI
746 AM EDT SAT MAR 24 2007 .AVIATION...UPPER LEVEL SHORTWAVE WILL SWEEP ACROSS NORTHERN MICHIGAN LATER THIS MORNING. BUILDING HIGH PRESSURE AND STRONG DRYING BEHIND DEPARTING SYSTEM WILL HELP SCOUR OUT LOW LEVEL MOISTURE AND ASSOCIATED VFR-MVFR CLOUD DECK AND VISIBILITIES BY THIS AFTERNOON. CEILINGS/VIS EXPECTED TO REMAIN UNOBSTRUCTED LATER THIS AFTERNOON THROUGH THE OVERNIGHT AS HIGH PRESSURE REMAINS IN CONTROL. WINDS EXPECTED TO REMAIN UNDER 10 KNOTS ALL TAF SITES THROUGH THIS TAF CYCLE. MSB && .DISCUSSION...ISSUED AT 347 AM. WESTERN GREAT LAKES BENEATH CONFLUENCE ZONE WHERE UPSTREAM SPLIT FLOW MERGING BACK TOGETHER. NORTHERN BRANCH WAVE ALONG U.S./CANADIAN BORDER WILL SWING THROUGH THE STATE TODAY...WHILE SOUTHERN BRANCH UPPER LOW OVER NORTHERN MEXICO BEGINS TO LIFT OUT THROUGH THE PLAINS STATES AND WILL EVENTUALLY HAVE AN IMPACT ON NORTHERN MI WEATHER DURING THE LATTER PORTION OF THE WEEKEND AND INTO EARLY NEXT WEEK. IN GENERAL HOWEVER A RATHER MILD PERIOD SHAPING UP OVER THE NEXT WEEK. MAIN FORECAST CONCERNS WILL DEAL WITH NUISANCE PRECIPITATION AND CLOUD COVER ISSUES TODAY...THEN EVOLUTION OF RAIN CHANCES FOR LATER SUNDAY AND BEYOND AS REMNANTS OF SOUTHERN BRANCH WAVE GET INTO THE ACT. TODAY/TONIGHT...COUPLE OF FEATURES OF NOTE TO START OUT THE FORECAST THIS MORNING. LOW/MID CLOUD HAS BEEN ADVANCING NORTHWARD ACROSS THE LOWER PENINSULA IN AN AREA OF LOW/MID LEVEL WARM ADVECTION NORTH OF STATIONARY FRONTAL BOUNDARY WHICH LIES ACROSS IA/IL/SOUTHERN OH. VARIOUS AIRCRAFT SOUNDINGS ACROSS SOUTHERN LOWER/WI INDICATE MOISTURE LAYER EXTENDS TO ABOUT 600MB...A FAIR AMOUNT DEEPER THAN EXPECTED WHICH HAS BEEN ENOUGH TO ALLOW FOR SCATTERED SHOWERS TO DEVELOP GENERALLY SOUTH OF M-72. TO THE NORTHWEST...WATER VAPOR IMAGERY SHOWS A SHORT WAVE TROUGH ALONG THE MN/ONTARIO BORDER. GOOD DEAL OF MID/HIGH CLOUD WITH THIS FEATURE ADVANCING ACROSS FAR NORTHERN WI/WESTERN UPPER...SOME RADAR RETURNS WITH THIS BUT LITTLE REACHING THE GROUND AS LOWER LAYERS QUITE A BIT DRIER IN 00Z INL/MPX SOUNDINGS. DEALING WITH THE LOWER PENINSULA SHOWER ACTIVITY FIRST...LOOKS LIKE THIS WILL MAINLY BE AN EARLY MORNING ISSUE...IR/RADAR TRENDS SUGGEST THAT BY PRESS TIME SHOULD BE ABLE TO CONFINE EARLY POPS EAST OF US-131/SOUTH OF M-68. ANTICIPATE SHOWER ACTIVITY TO BE EAST OF THE FORECAST AREA BY 15Z. AS FOR THE NORTHERN STREAM SHORT WAVE...CURRENT FORECAST HAS SOME MORNING RAIN CHANCES ACROSS EASTERN UPPER AND THE STRAITS...AND SEE NO REASON NOT TO KEEP THIS GOING. NOT MUCH GOING ON UPSTREAM AS FAR AS SURFACE REPORTS OF PRECIPITATION ARE CONCERNED THOUGH LOW LEVELS AS MENTIONED EARLIER ARE QUITE A BIT DRIER. IR/FOG IMAGERY SHOWS LOW LEVEL MOISTURE SURGING NORTH ACROSS NORTHERN LAKE MICHIGAN AND TOWARD EASTERN UPPER...AND THIS SHOULD AID CHANCES OF SOME LIGHT PRECIP REACHING THE GROUND LATER THIS MORNING AS THE UPPER DYNAMICS ROLL THROUGH. PRECIP CHANCES SHOULD END ACROSS EASTERN UPPER BY EARLY AFTERNOON AS SHORT WAVE PASSES BY AND DRIER AIR SWEEPS IN FROM THE WEST. SO ANTICIPATE DECREASING CLOUDINESS AS THE AFTERNOON WEARS ON ACROSS THE ENTIRE AREA. SOME LAKE BREEZE COMPONENT TO THE WIND FIELDS EXPECTED THIS AFTERNOON...ESPECIALLY ALONG THE LAKE HURON SHORELINE NORTH OF APN AND AROUND THE EASTERN END OF THE UPPER PENINSULA. QUIET NIGHT LOOKS TO BE IN STORE FOR TONIGHT...PERHAPS A LITTLE PATCHY FOG DEVELOPING BEFORE WINDS PICK UP AFTER MIDNIGHT...AND EXPECTING AN INCREASE IN HIGH CLOUDS OVERNIGHT AS WELL. AS FOR ONGOING HYDRO ISSUES...WILL DROP FLOOD WATCHES AT FORECAST ISSUANCE TIME...AND LET ARENAC COUNTY FLOOD WARNING STAND ON ITS OWN. SOUTH BRANCH TOBACCO/RIFLE RIVERS HAVE CRESTED AND ARE ON THEIR WAY DOWN. SUNDAY...FORECAST FOR SUNDAY CONTINUES TO OSCILLATE BACK AND FORTH AS TO WHETHER OR NOT ANY PRECIPITATION IS GOING TO MAKE IT INTO THE AREA DURING THE DAYTIME. GUIDANCE IS TRENDING BACK TOWARD TRYING TO PUSH AT LEAST SOME REMNANT WARM ADVECTION PRECIP ACROSS THE STATE FROM THE SOUTH SUNDAY...MAIN MODEL DISCREPANCY APPEARS TO BE IN TIMING OF BETTER LOW LEVEL MOISTURE RETURN (GFS/UKMET QUICKER...NAM SLOWER). CURRENT FORECAST HAS AFTERNOON RAIN CHANCES ACROSS FAR SOUTHWEST PORTION OF THE FORECAST AREA AND THIS STILL LOOKS FINE...WILL ACKNOWLEDGE GUIDANCE TREND AND EXPAND PRECIP CHANCES A LITTLE FARTHER INLAND DURING THE AFTERNOON...KEEPING MAINLY NORTHEAST LOWER DRY UNTIL SUNDAY EVENING. MAIN AREA OF CONVECTION WILL BE DEVELOPING ALONG FRONTAL BOUNDARY AND AHEAD OF SHORT WAVE TROUGH ACROSS MN/WI/IA/IL...WHICH WILL ALL LIFT EAST/ NORTHEAST AND SPREAD ACROSS THE FORECAST AREA AFTER MIDNIGHT ALONG NOSE OF 40+KT LOW LEVEL JET. MONDAY THROUGH WEDNESDAY...SHORT WAVE ENERGY AND ASSOCIATED CONVECTION WILL ROLL THROUGH NORTHERN MI MONDAY MORNING...STILL LOOKS LIKE IT MAY DRY OUT DURING THE AFTERNOON. MONDAY NIGHT LOOKING A LITTLE MORE INTERESTING FROM THE STANDPOINT THAT IT MAY END UP BEING CLOUDY BUT DRY AS SURFACE BOUNDARY PRESSES IN FROM THE NORTH. NO REAL INSTABILITY APPEARS TO BE IN THE CARDS THOUGH SIGNS OF SOME TRAPPED LOW LEVEL MOISTURE COULD END UP WITH SOME FOG/DRIZZLE MORE THAN ANYTHING ELSE. HOW FAR SOUTH THE BOUNDARY GETS WILL THEN IMPACT POTENTIAL RAIN CHANCES FOR THE MIDWEEK PERIOD AS LEE CYCLOGENESIS LOOKS TO GET RAMPED UP BY WEDNESDAY... THE END RESULT MAY BE ANOTHER SURGE OF WARM ADVECTION PRECIP INTO THE STATE LATER TUESDAY INTO WEDNESDAY THOUGH INITIAL SURGE OF RAIN MAY BE BLUNTED BY DRY EASTERLY FLOW AROUND HUDSON BAY SURFACE HIGH. A LOT OF UNCERTAINTY REGARDING THIS HOWEVER...WHICH ARGUES FOR FEW CHANGES TO GOING FORECAST AND THAT SEEMS TO BE THE CONSENSUS. WILL GO DRY ACROSS EASTERN UPPER FOR TUESDAY...WITH LOW CHANCE POPS ACROSS NORTHERN LOWER. WILL KEEP WEDNESDAY DRY FOR NOW...IT MAY TURN OUT THAT THE TUESDAY/WEDNESDAY FORECASTS WILL NEED TO BE SWAPPED (DRY TUESDAY/RAIN WEDNESDAY). && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ JPB
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
934 AM CDT SAT MAR 24 2007 .UPDATE...A 12Z TAMDAR SOUNDINGS FROM TVF INDICATES THE FOG IS ALMOST 2 KFT THICK THERE AND EVEN WITH A STRONG MARCH SUN IT WILL TAKE AWHILE TO BURN OFF. IT PROBABLY MORE SHALLOW AROUND THE FRINGES...NEAR GFK AND BJI BUT IS QUITE DENSE ATTM AND CERTAINLY WORTHY OF EXTENDING THE ADVISORY. DEEP INTO THIS CLOUD DECK SUCH AS ROX AND BDE STRATUS IS MORE COMMON SO TRANSITIONED THE FOG TO AREAS THERE. BUT FOG HAS MOSTLY BURNED OFF WEST OF RED RIVER VALLEY SO ALLOW THE FOG ADVISORY TO EXPIRE AS EXPECTED THERE. ADVISORY WAS ISSUED FOR NORTH RED RIVER VALLEY AND NORTHWEST MN UNTIL NOON. AHEAD OF THE ADVANCING FOG ON THE SOUTHERN EXTENT... EXPECT THE SUN TO SLOW THE ADVANCE AND LIFT IT TO A STRATUS LAYER BEFORE REACHING FAR...DTL AND PKD. GIVEN THIS FOG AND STRATUS HAVE ADJUSTED THE TEMPERATURES TODAY A BIT. THINK WARMING WILL HAPPEN QUICKLY ONCE IT DOES BURN OFF SO DID NOT LOWER MAX READINGS BELOW THE 50S. WILL HAVE TO WATCH THE STRATUS TO MAKE SURE IT DOES GO AWAY. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...DENSE FOG ADVISORY UNTIL NOON CDT TODAY FOR NDZ008-016-027-030. MN...DENSE FOG ADVISORY UNTIL NOON CDT TODAY FOR MNZ001-002-004>009- 013>017-022-023. && $$ GV
AREA FORECAST DISCUSSION
NWS SEATTLE WA
925 AM PDT SAT MAR 24 2007 .SYNOPSIS...A STRONG FRONTAL SYSTEM WILL CONTINUE TO BRING RAIN THROUGH THIS EVENING. A COOLER AIR MASS WILL MOVE INTO THE REGION SUNDAY BEHIND THE FRONT. THE REGION SHOULD SEE DRY WEATHER FOR THE FIRST PART OF THE WEEK...THEN WET AGAIN AFTER WEDNESDAY. && .SHORT TERM...VIGOROUS FNTL SYSTEM TODAY WITH FROPA PGTSND ARND 06Z THIS EVENING. AT H850 OFF THE MM5NAM WE SEE TEMPS AROUND +5C AT H850 TODAY AND WIND UP AROUND 50KTS SO THE PINEAPPLE EXPRESS CONTINUES. THEN WITH FROPA THE 0C ISOTHERM IS INTO THE CASCADES AROUND 06Z WITH TEMP AROUND -3C SUNDAY IN LIGHT WLY FLOW. OBVIOUSLY ANOTHER 12-15 HOURS OF RAIN IN THE MOUNTAINS...THEN AS THE PRECIP TAPERS OFF THE SNOW LEVEL DROPS DOWN TO AROUND PASS LEVEL AROUND MIDNIGHT TONIGHT. WINDY IN SOME AREAS TODAY...THE WIND AT KPAE HAS BEEN AROUND 30MPH. HOWEVER THE 8 AND 9AM OBS FROM WILSON AND SMITH ISLAND ONLY SHOW 10KTS OR LESS DESPITE OUR GALE WARNING. FOR NOW...THE OLYMPICS SEEM TO BE BLOCKING THE WINDS RATHER THAN ENHANCING THEM WITH A LEE SIDE LOW. STRONGEST WINDS MAY END UP BEING ON THE EDMONDS KINGSTON RUN TODAY. I HAVE NOT YET DECIDED WHAT TO DO WITH THE WIND ADVISORY WHICH KICKS IN AT 10AM AND GOES TIL 7PM...PROBABLY WONT CHANGE IT AND WINDS SHOULD INCREASE AGAIN WITH THIS NEXT PLUME OF 50KTS AT H850 AND 40KTS AT 2000FT...PLUS SEE THE MARINE DISCUSSION BELOW FOR THE EXPECTATION THAT WINDS WILL INCREASE RAPIDLY AGAIN BACK TO GALE FORCE THOSE AREAS. MM .LONG TERM...DRY MON TUE AND PERHAPS MOST OF THE DAY WED...AND RAIN AT TIMES THU-SAT BASED ON THE OVERNITE GFS. IF THE 12Z GFS FOLLOWS THE PREVIOUS RUNS WILL MAKE NEXT WEEKEND WET AND JUST BROADBRUSH THU-SUN WITH RAIN. MM && .AVIATION...ACARS SOUNDINGS REPORTING 850 MB WINDS SWLY AT 40 KNOTS THIS MORNING. WSR-88D PRECIPITATION ECHOES SHOW THE RAIN SHADOW FROM THE OLYMPICS PRETTY WELL FROM ABOUT KBFI-KPAE. BRIEF BREAK IN THE HEAVIER PRECIPITATION THIS MORNING INTO THIS AFTERNOON, PRECIPITATION RATES PICKING UP AGAIN LATER THIS AFTERNOON. FRONTAL PASSAGE TIMED FOR THE COAST AROUND 03Z...KSEA 06Z. AHEAD OF THE FRONT OUTSIDE THE RAIN SHADOWED AREAS IN THE INTERIOR CEILINGS GENERALLY IN THE 1500 TO 2500 FOOT RANGE WITH ISOLATED VISIBILITIES 3-5SM WITH LIGHT RAIN. ALONG THE COAST CONDITIONS REMAINING LOW UNTIL FRONTAL PASSAGE WITH CEILINGS AOB 1000 FEET AND VIS 1-3SM WITH RAIN. CENTRAL SOUND CEILINGS ALL OVER THE PLACE FROM 500 TO 5000 FEET. EXPECT THE RAIN SHOW TO FILL IN THIS AFTERNOON WITH CEILINGS SETTLING IN THE 1500 TO 2500 FOOT RANGE. LOCAL VISIBILITIES 3-5SM WITH RAIN LATER THIS AFTERNOON UNTIL FRONTAL PASSAGE. KSEA...CEILINGS BELOW 1000 FEET UNTIL 18Z...AFTER 18Z CEILINGS GENERALLY 2000 TO 3000 FEET WITH VISIBILITIES LOWERING TO 5 SM AT TIMES. WINDS SOUTHERLY 15 KNOTS GUSTING TO 25 KNOTS THROUGH THIS EVENING. && .MARINE...SOUTHERLY WINDS WILL INCREASE RAPIDLY BETWEEN 16Z AND 20Z AS A 990MB LOW MOVES INTO QUEEN CHARLOTTE SOUND AND AS STRONG LOW LEVEL AND MID LEVEL WINDS ALOFT INTERACT WITH THE OLYMPIC MOUNTAINS AND MOUNTAINS OF VANCOUVER ISLAND. FROM ABOUT 18Z UNTIL FRONTAL PASSAGE BETWEEN 03Z AND 06Z FROM THE WEST...EXPECT GALE FORCE WINDS AT AREAS PRONE TO SOUTH/SOUTHEAST WINDS SUCH AS THE COAST...ENTRANCES TO THE STRAIT...ADMIRALTY INLET...AND NORTH INLAND WATERS. WHILE GALES MAY SUBSIDE AT TIMES AS A MESOSCALE LOW NE OF THE OLYMPICS WOBBLES AROUND...THEY SHOULD RAPIDLY REDEVELOP AS THE LOW WOBBLES AGAIN. EXPECT WINDS TO GENERALLY REMAIN IN THE 20-30KT RANGE IN PUGET SOUND AND HOOD CANAL. WINDS WILL VEER TO MORE WESTERLY AND RELAX BEHIND THE FRONT. WINDS WILL SLOWLY SUBSIDE LATER TONIGHT AS HIGH PRES BUILDS INTO THE AREA. FELTON && .SEW WATCHES/WARNINGS/ADVISORIES... .GALE WARNING COAST...ENTRANCES TO THE STRAIT...ADMIRALTY INLET...AND NORTHERN INLAND WATERS. .SMALL CRAFT ADVISORY...PUGET SOUND AND HOOD CANAL... CENTRAL STRAIT...GRAYS HARBOR FOR ROUGH BAR CONDITIONS. .FLOOD WATCH FOR PORTIONS OF WRN WA. $$ WEATHER.GOV/SEATTLE
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
200 PM PDT SAT MAR 24 2007 .SHORT TERM (TODAY-MONDAY)...SATELLITE IMAGERY SHOWING VERY DISORGANIZED MARINE LAYER COVERAGE THIS AFTERNOON...WITH GOOD CLEARING ACROSS VENTURA COUNTY...BUT ONLY PARTIAL CLEARING ACROSS PORTIONS OF LA BASIN AS WELL AS CENTRAL COAST AND SBA COUNTY SOUTH COAST. EARLIER ACARS DATA AND PILOT REPORTS INDICATED A MARINE LAYER DEPTH OVER 4000 FEET EARLIER THIS MORNING...BUT CURRENT DATA SUGGESTS A DEPTH AROUND 2500 FEET. AS UPPER LEVEL RIDGE BUILDS OVER AREA TONIGHT AND SUNDAY...LOOK FOR MARINE LAYER TO CONTINUE TO SHRINK WITH TIME. NONTHELESS...WE SHOULD SEE SOME LOW CLOUDS AND FOG RETURN TO SOME VALLEY AREAS OVERNIGHT. THE MARINE LAYER IS THEN EXPECTED TO DEEPEN SOMEWHAT LATE SUNDAY NIGHT INTO MONDAY IN ADVANCE OF THE NEXT UPPER LEVEL TROUGH. SLIGHT WARMING IN MANY AREAS EXPECTED ON SUNDAY...WITH A FEW DEGREES OF COOLING EXPECTED ON MONDAY. NEXT STORM SYSTEM WILL BRING A THREAT OF RAIN AND MOUNTAIN SNOW TO THE REGION ON MONDAY NIGHT INTO TUESDAY. AT THIS POINT...MODELS ARE GENERALLY TRENDING TOWARDS BRINGING A NARROW BAND OF RAIN ASSOCIATED WITH A FAST MOVING FRONTAL BAND INTO THE CENTRAL COAST ON MONDAY EVENING...SPREADING RAPIDLY THROUGH VENTURA AND LA COUNTIES OVERNIGHT MONDAY NIGHT. WHILE AVAILABLE MOISTURE IS LIMITED WITH THIS SYSTEM...LATEST MODEL RUNS CONTINUE TO ADVERTISE FAIRLY GOOD DYNAMICS AND COLD AIR ADVECTION. A STRONG 130 KNOT WESTERLY JET WITH ASSOCIATED UPPER LEVEL DIVERGENCE COMBINED WITH A STRONG AREA OF PVA SHOULD BE ABLE TO HOLD FRONTAL BAND TOGETHER ACROSS LA BASIN WHICH CURRENT WRF MODEL CROSS SECTIONS CONTINUE TO ADVERTISE. BEHIND THE MAIN FRONTAL BAND...THERE WILL BE A VERY COLD AND SLIGHTLY UNSTABLE AIR MASS WHICH WILL BRING A THREAT OF SHOWERS AND EVEN A SLIGHT CHANCE OF THUNDERSTORMS THROUGH TUESDAY...ALTHOUGH IT NOW APPEARS THAT CLOUD COVERAGE AND PRECIPITATION CHANCES MAY DECREASE DURING THE AFTERNOON HOURS. AT THIS POINT...STILL FEEL THAT BEST THREAT OF PRECIPITATION WILL BE FROM SBA COUNTY NORTHWARD...AND HAVE BUMPED UP POPS TO LIKELY CATEGORY IN THIS AREA...BUT WILL KEEP WITH CHANCE POPS DOWN SOUTH FOR NOW UNTIL THERE IS GOOD RUN TO RUN MODEL CONSISTENCY. SINCE THIS SYSTEM WILL LIKELY BE MORE CONVECTIVE IN NATURE...THERE WILL LIKELY BE WIDELY VARYING RAINFALL TOTALS...BUT IT IS QUITE POSSIBLE THAT SOME AREAS COULD PICK UP BETWEEN ONE TENTH AND ONE HALF INCH OF RAIN. THIS SYSTEM CERTAINLY HAS PLENTY OF COLD AIR ALOFT WITH 500 MB TEMPERATURES PROGGED TO RANGE BETWEEN -25 AND -30 DEGREES CELSIUS LATE MONDAY NIGHT INTO TUESDAY MORNING. WITH THE RAPID COLD AIR ADVECTION ALOFT...THERE COULD CERTAINLY BE A THREAT OF THUNDERSTORMS WITH BRIEF HEAVY DOWNPOURS AND SMALL HAIL. VERY LOW SNOW LEVELS WILL LIKELY BE THE MOST PROMINENT FEATURE OF THIS SYSTEM...WITH SNOW LEVELS LIKELY FALLING TO BETWEEN 3000 AND 3500 FEET LATE MONDAY NIGHT INTO TUESDAY MORNING. MOUNTAIN AREAS COULD SEE ANYWHERE BETWEEN 2 AND 4 INCHES OF NEW SNOW WITH THIS SYSTEM. THESE LOW SNOW LEVELS COULD BRING ACCUMULATING SNOW TO THE FOOTHILLS OF THE CUYAMA AND ANTELOPE VALLEYS...AS WELL AS INTERSTATE 5 NEAR THE GRAPEVINE. ANOTHER INTERESTING FEATURE WITH THIS STORM COULD BE GUSTY WEST WINDS BEHIND THE FRONT LATE MONDAY NIGHT INTO TUESDAY. .LONG TERM (WEDNESDAY-SATURDAY)...CLEARING SKIES SHOULD SPREAD ACROSS THE AREA TUESDAY NIGHT INTO WEDNESDAY. WHILE TEMPERATURES SHOULD BEGIN TO SLOWLY MODERATE ON WEDNESDAY...WE SHOULD SEE MORE DRAMATIC WARMING ON THURSDAY AS THE FLOW TURNS OFFSHORE. WEAK TO MODERATE OFFSHORE FLOW SHOULD CONTINUE FRIDAY INTO SATURDAY WITH A CONTINUED WARMING TREND. HIGH TEMPERATURES SHOULD CLIMB WELL INTO THE 80S IN THE VALLEYS ON FRIDAY AND SATURDAY. && .AVIATION...24/2100Z EDDY CIRCULATION FROM THIS MORNING HAS GIVEN WAY TO MOSTLY ONSHORE FLOW. MOST AIRFIELDS S OF KSBA HAVE EXPERIENCED SOME CLEARING...BUT SHOULD BE SHORT LIVED AS STRATUS SHOULD REFORM AROUND 03Z AND BEGIN ITS MARCH INLAND SHORTLY THEREAFTER. KSBA AND NORTHWARD WILL CONTINUE TO BE UNDER STRATUS THROUGH TONIGHT. CIGS WILL LOWER OVERALL THROUGH THE NIGHT DOWN TO IFR/MVFR...AS MARINE SHOULD SHRINK SOME...MUCH DIFFERENT FROM THE RAPID DEEPENING SEEN TODAY ASSOCIATED WITH THE BROAD SOUTHERLY FLOW. KLAX SHOULD SEE SOME SCT DECKS...BUT MAY GO ON AGAIN OFF AGAIN SCT TO BKN 028 THROUGH ABOUT 04Z...THEN GO SOLID OVC SOON THEREAFTER. CIGS SHOULD BE LOWER OVERALL TONIGHT...NEAR 018 BY 06Z....AND POSSIBLY LOWERING DOWN TO NEAR 010 BY SUNRISE. WESTERLY WIND SHOULD CONTINUE AT AROUND 10 KT...THEN GO WEAK. NO SIGNIFICANT SOUTHEAST WINDS EXPECTED OVER 6 KT THROUGH SUN MORNING. KBUR WILL SEE CLEARING THROUGH ABOUT 04Z...WITH A LIKELY STRATUS SURGE SOON THEREAFTER. STRATUS WILL RETURN WITH LOWERED CIGS...AND A GOOD SHOT OF GOING BELOW 010 AFTER 10Z. SOUTH WINDS WILL CONTINUE UNTIL ABOUT 03Z...THEN STAY LIGHT THROUGH THE REST OF THE NIGHT. && .MARINE... A COLD FRONT WILL PASS THROUGH THE COASTAL WATERS LATE MONDAY. THIS STORM WILL BRING INCREASED NW WIND...POSSIBLY REACHING GALE CONDITIONS EARLY TUESDAY OVER THE OUTER AND INNER WATERS. THIS STORM WILL ALSO GENERATE A RELATIVELY LARGE WESTERLY SWELL BY TUESDAY. SEA HEIGHTS ARE EXPECTED TO REACH 14 FT OVER THE OUTER WATERS AND PUSH CLOSE TO 10 FT OVER THE INNER WATERS. THE COMBINATION OF THIS LARGE SWELL...GUSTY WINDS...AND POSSIBLE THUNDERSTORMS WILL CREATE POTENTIALLY HAZARDOUS SEA CONDITIONS FROM LATE MONDAY THROUGH WEDNESDAY. MARINERS SHOULD KEEP ABREAST OF THIS DEVELOPING SITUATION FOR EARLY NEXT WEEK. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. && $$ PUBLIC...GOMBERG AVIATION/MARINE...KITTELL WWW.WEATHER.GOV/LOSANGELES
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATE
NWS LOS ANGELES/OXNARD CA
1030 AM PDT SAT MAR 24 2007 UPDATED AVIATION DISCUSSION .SHORT TERM (TODAY-MONDAY)...MARINE LAYER HAS DEEPENED RAPIDLY THIS MORNING ACROSS THE LA BASIN...WITH PILOT REPORTS AND ACARS DATA INDICATING A DEPTH AROUND 4000 FEET. AS A RESULT...LOW CLOUDS AND FOG HAVE SURGED WELL INTO THE SANTA CLARITA VALLEY AND LOWER COASTAL SLOPES DURING THE PAST FEW HOURS. THE BIG QUESTION MARK TODAY WILL BE THE AMOUNT OF STRATUS BURNOFF. THERE MAY BE SOME DIFFICULTY IN CLEARING ACROSS SOME AREAS TODAY...SO PARTLY CLOUDY OR PARTIAL AFTERNOON CLEARING WORDING HAS BEEN MENTIONED IN CURRENT ZONE PACKAGE. WITH THE DEEPENING MARINE LAYER...WILL SEE A SIGNIFICANT DROP IN TEMPERATURES TODAY ACROSS MOST AREAS...WITH MOST COASTAL AND VALLEY AREAS REMAINING IN THE 60S. THE ANTELOPE VALLEY WILL CONTINUE TO SEE WARM TEMPERATURES WELL INTO THE 70S. *** FROM PREVIOUS DISCUSSION *** WEAK RIDGING WILL REMAIN IN PLACE THROUGH AT LEAST SUNDAY AFTERNOON AS DEVELOPING TROUGH IN THE GULF OF ALASKA PUSHES DOWN TO THE WEST COAST. MODELS STILL ARE STRUGGLING WITH MODELING THE TROUGHS INTENSITY SOME. POPS AND WEATHER HAVE BEEN CHANGED VERY LITTLE AS THIS SERIES OF MODEL RUNS HAS BACKED OFF THE TROUGHS STRENGTH. THE TROUGH TILT...WHICH THE ALL MODELS INDICATED A FAIR AMOUNT OF IN PREVIOUS RUNS...IS PRETTY MUCH NON-EXISTENT. IN ADDITION TO THE TROUGH BEING VERTICALLY STACKED...LATEST 850 MB TEMPERATURE PATTERN INDICATES LITTLE PRESENCE OF WARM AIR ADVECTION OCCURRING AHEAD OF THE TROUGHS FRONTAL BOUNDARY. TIMING APPEARS TO BE PRETTY CONSISTENT AMONGST ALL MODEL SOLUTIONS THOUGH...WITH PRECIPITATION ARRIVING ALONG THE CENTRAL COAST MONDAY AFTERNOON OR EVENING. .LONG TERM (TUESDAY-FRIDAY)...PRECIPITATION THREAT SHOULD SHIFT SOUTHWARD INTO THE SOUTHLAND LATE MONDAY NIGHT OR INTO TUESDAY MORNING. COLD AIR ARRIVES RAPIDLY BEHIND THE FRONTAL BOUNDARY...WITH 500 MB AND 700 MB TEMPERATURES DROPPING RAPIDLY. CONVECTIVE SHOWERS AND THUNDERSTORMS SHOULD OCCUR BEHIND IN THE COLD AIR SECTOR AS 500 MB TEMPERATURES DROP BELOW -25 CELSIUS ON TUESDAY MORNING. TREND MAY ALSO INDICATE THAT PRECIPITATION WITH THIS STORM SYSTEM MAY VERY LIKELY BE MORE SHOWERY THAN STRATIFORM. CLEARING SHOULD COMMENCE ON TUESDAY AFTERNOON AND TUESDAY NIGHT AS UPPER-LEVEL PATTERN SETS UP FOR A SERIES OF OFFSHORE FLOW EVENTS FOR MIDWEEK. GFS INDICATES RATHER MODERATE EVENTS AT THE CURRENT TIMES...WITH ADVISORY LEVEL WINDS LIKELY OCCURRING. AMPLE THERMAL AND PRESSURE GRADIENTS DEVELOP TUESDAY AFTERNOON INTO AT LEAST THURSDAY MORNING FOR OFFSHORE WINDS. MUCH DIVERGENCE OCCURS AS FAR AS WHAT MAY HAPPEN FOR LATE NEXT WEEK. GFS AND ECMWF CONTINUE TO INDICATE GENERAL RIDGE PATTERN CONTINUING BUT SOME MODEL RUNS ARE CARVING A TROUGH THROUGH THE RIDGE PATTERN. FORECAST KEEPS RIDING PATTERN IN PLACE FOR NOW. && .AVIATION...24/1730Z EDDY CIRCULATION FROM THIS MORNING HAS CREATED BROAD SOUTHERLY FLOW WITH A RAPIDLY DEEPENING MARINE LAYER AT ALL COASTAL AND VALLEY AIRFIELDS. FLOW IS STARTING TO TURN ONSHORE AS OF 17Z AND CLEARING ACTUALLY LOOKS POSSIBLE AT MOST SITES. AFTER 20Z...ALL AIRFIELDS SHOULD BE VFR...EXCEPT FOR KSBA AND KOXR POSSIBLY SEEING AN OCCASIONAL MVFR CIG THROUGH 22Z OR SO. WINDS WILL BE RELATIVELY LIGHT TODAY...EXCEPT FOR KWJF AND KPMD POSSIBLY SEEING SW WINDS NEAR 15 KT LATER THIS AFTERNOON. KLAX WILL CONTINUE TO IMPROVE...WITH A VFR CIG ABOVE 030 CONTINUING THROUGH 20Z. STRATUS ERODING TO THE SOUTHEAST OF THE AIRPORT...AND THAT CLEARING SHOULD REACH KLAX BY 20Z. SHOULD START TO SEE A SHIFT IN THE WIND FROM SOUTHEAST...TO SOUTHWEST AROUND 10 KT. STRATUS WILL RETURN THIS EVENING AFTER 04Z...BUT MAY RETURN A LITTLE EARLIER...WITH CIGS LOWER...NEAR 018 AT THE ONSET. KBUR WILL CONTINUE TO SEE A CIG THROUGH 21Z...BUT MAY POP ABOVE 030 BETWEEN 18Z-20Z...WITH CLEARING LIKELY AFTER 21Z. SOUTH WINDS NEAR 08 KT WILL CONTINUE INTO THE EVENING. STRATUS WILL RETURN AROUND 05Z...WITH LOWERED CIGS...AND A GOOD SHOT OF GOING BELOW 010 AFTER 10Z. && .MARINE... A COLD FRONT WILL PASS THROUGH THE COASTAL WATERS LATE MONDAY. THIS STORM WILL BRING INCREASED NW WIND...POSSIBLY REACHING GALE CONDITIONS EARLY TUESDAY OVER THE OUTER AND INNER WATERS. THIS STORM WILL ALSO GENERATE A RELATIVELY LARGE WESTERLY SWELL BY TUESDAY. SEA HEIGHTS ARE EXPECTED TO REACH 14 FT OVER THE OUTER WATERS AND PUSH CLOSE TO 10 FT OVER THE INNER WATERS. THE COMBINATION OF THIS LARGE SWELL...GUSTY WINDS...AND POSSIBLE THUNDERSTORMS WILL CREATE POTENTIALLY HAZARDOUS SEA CONDITIONS FROM LATE MONDAY THROUGH WEDNESDAY. MARINERS SHOULD KEEP ABREAST OF THIS DEVELOPING SITUATION FOR EARLY NEXT WEEK. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PACIFIC COASTAL WATERS... SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS (SEE LAXCWFLOX). && $$ PUBLIC...GOMBERG/HALL AVIATION/MARINE...KITTELL WWW.WEATHER.GOV/LOSANGELES