Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 03/21/07

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
1100 AM PDT MON MAR 19 2007 .SHORT TERM... 16Z AMDAR DATA (ACARS) SHOWS THE DEPTH OF THE MARINE LAYER AT AROUND 3800 FEET. ADD IN A MODERATE TO STRONG ONSHORE PRESSURE GRADIENT FOR KLAX-KDAG AT OVER 5 MB AND ONE WOULD NOT EXPECT TOO MUCH CLEARING OF THE LOW CLOUDS AND FOG THIS AFTERNOON. IN FACT...THE LOW CLOUDS AND FOG ARE CURRENTLY AT THE DOORSTEP OF PALMDALE HAVING NEGOTIATED THEIR WAY THROUGH MUCH OF SOLEDAD CANYON. WOULD NOT BE SURPRISED TO HEAR OF SOME LOCALLY DENSE FOG IN PORTIONS OF SOLEDAD CANYON. ONLY VALLEY SECTIONS ARE LIKELY TO SEE SOME SUNSHINE THIS AFTERNOON. GUSTY WINDS WILL BE RATHER STRONG FOR THE ANTELOPE VALLEY TODAY...PERHAPS A LITTLE STRONGER THAN CURRENTLY FORECAST...THANKS TO THE STRONG ONSHORE FLOW. FOR TONIGHT AND TUESDAY...SOUTHWEST CALIFORNIA CAN EXPECT CONTINUED LOW CLOUDS AND FOG IN THE COASTAL AND VALLEY SECTIONS WHILE THE MOUNTAINS AND DESERTS WILL HAVE MOSTLY CLEAR TO PARTLY CLOUDY SKIES. WITH LOWERING HEIGHTS AS A TROUGH APPROACHES THE FORECAST AREA...EXPECT THE DAYTIME TEMPERATURES TO DROP A FEW DEGREES...THE GREATEST DROP TAKING PLACE IN THE INTERIOR SECTIONS. TUESDAY NIGHT AND WEDNESDAY...A TROUGH IN THE EASTERN PACIFIC WOULD HAVE TO OVERCOME SEVERAL FACTORS TO BRING MUCH RAIN TO THE AREA. THE MODELS SEEM TO BE IN SOME DISAGREEMENT WITH THE GFS MORE FORCEFUL IN BRINGING A DECENT SHOT OF PRECIPITATION TO THE NORTHERN AREAS. THE WRF MODEL SEEMS TO BE INDICATING A WEAKER SYSTEM PERHAPS DUE TO A SPLIT FLOW ALONG THE WEST COAST....LIMITED MOISTURE...AND A LACK OF ANY LOW LEVEL SOUTHERLY FLOW IN ADVANCE OF THE SYSTEM. IN ANY CASE...WILL RAISE THE POPS A BIT FOR SECTIONS NORTH OF POINT CONCEPTION. THE PRECIPITATION WILL AFFECT THE CENTRAL COAST BY LATE AFTERNOON OR EARLY EVENING TUE. ON WEDNESDAY...THE SOUTHERN END OF THE TROUGH EVOLVES INTO A CUTOFF LOW OFF THE SOUTHWEST CALIFORNIA COAST WHICH WILL CONTINUE A SMALL THREAT OF SHOWERS THROUGH WEDNESDAY. WEDNESDAY NIGHT AND THURSDAY...THE UPPER LOW WILL DRIFT SLOWLY TO THE SOUTHEAST DURING THIS PERIOD PLACING THE FORECAST ON THE NORTHERN PERIMETER OF THE CLOSED CIRCULATION. THE EASTERN SAN GABRIEL MOUNTAINS IN LOS ANGELES COUNTY MAY GET SOME WRAP AROUND MOISTURE...OTHERWISE SURFACE HIGH PRESSURE BUILDING OVER THE GREAT BASIN IN ADDITION TO EASTERLY FLOW ALOFT WILL PRODUCE SOM GUSTY OFFSHORE WINDS ON THURSDAY ALONG WITH A DECENT CLEARING TREND. .LONG TERM...FROM PREVIOUS DISCUSSION... A NICE LITTLE OFFSHORE EVENT IS SHAPING UP THURSDAY AS A CUT OFF LOW SW OF SAN DIEGO WILL PULL THE UPPER FLOW OFFSHORE TO COMPLEMENT THE BUILDING OFFSHORE SURFACE PRESSURE TREND. RIGHT NOW IT LOOKS LIKE IT WILL COME IN AT LESS THE WAD STRENGTH BUT THE MDLS HAVE BEEN TRENDING IT STRONGER WITH EACH RUN. A WEAK RIDGE WILL BUILD IN OVER THE AREA FRIDAY THROUGH NEXT SUNDAY AND THE WEATHER WILL BE PLEASANT IF A LITTLE DULL. TEMPS WILL RISE TO NEAR NORMAL AND MAYBE A DEGREE OR TWO ABOVE NORMS. && .AVIATION... 19/1740Z MARINE LAYER HAS PUSHED UP TO ABOUT 3800 FT THIS MORNING...WITH A PERSISTENT EDDY STILL IN PLACE. CLEARING WILL BE SPARSE ONCE AGAIN...BUT MOST CIGS WILL PUSH ABOVE 030 AND VFR BY 20Z. KVNY AND KBUR SHOULD SEE CLEARING NEAR 22Z...BUT MIGHT ACTUALLY OCCUR A BIT BEFORE THAT. KPRB KSBP AND KSMX SHOULD SEE CLEARING BETWEEN 19Z AND 21Z...BUT WILL NOT LAST LONG...WITH MOST OF THOSE AIRFIELDS SEEING MVFR CIGS RETURNING NEAR 03Z. GUSTY WESTERLY WINDS ONCE AGAIN AT KPMD AND KWJF THROUGH ABOUT 03Z...PEAKING AROUND 23Z. KLAX...STRATUS SHOULD REMAIN...BUT SHOULD PUSH INTO VFR ABOVE 030 BY 21Z. CIGS WILL LOWER ONCE AGAIN NEAR 04Z. TYPICAL WESTERLY SEABREEZE NEAR 10 KT EXPECTED THROUGH 03Z OR SO. KBUR...CIGS WILL TEETER NEAR 020 THROUGH ABOUT 20Z. AFTER THAT...SCT-BKN025 CONDITIONS WILL PREVAIL. FAIRLY CONFIDENT THERE WILL BE A BREAK IN THE CIGS BETWEEN 21Z AND 03Z...BUT EXACT TIMING AND WHETHER OR NOT IT WILL BE PERSISTENT OR TEMPO IN NATURE IS UNCERTAIN. HAZE SHOULD LINGER AS WELL...BUT MAY GO UP TO 7SM DURING TIMES OF CLEARING. TYPICAL SOUTHERLY SEABREEZE AFTER 21Z. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXCWFLOX). && $$ PUBLIC...SWEET AVIATION...KITTELL WWW.WEATHER.GOV/LOSANGELES
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
315 AM PDT MON MAR 19 2007 .SHORT TERM... 08Z ACARS SOUNDING PLACES THE MARINE LAYER AT 2950 FEET. CURRENT DAG GRADIENT IS 6.9 ON ITS WAY TO A FORECAST VALUE OF +8.8MB AT 00Z THIS AFTERNOON WHICH IF TRUE WILL BE THE HIGHEST VALUE EVER RECORDED IN MARCH DURING THE 21ST CENTURY. THE WEATHER TODAY WILL BE MUCH LIKE SUNDAY WITH LITTLE OR NO CLEARING OVER THE COASTS SOUTH OF POINT CONCEPTION AND SOME BUT NOT TOTAL CLEARING OVER THE VALLEYS. THIS WILL SPARK GOOD WINDS IN THE ANTELOPE VALLEY AGAIN. CLOSE TO WIND ADVISORY CRITERIA BUT OT QUITE. THE MARINE LAYER WILL REFORM SOUTH OF POINT CONCEPTION TONIGHT AND WITH THE APPROACHING TROF SOME DRIZZLE MAY FALL ESP NEAR THE FOOTHILLS. NO THREAT OF ACTUAL RAIN TONIGHT AS TROF WILL HOLD OFF. WHERE THERE IS NOT A MARINE LAYER MID AND HIGH CLOUDS WILL INCREASE. TUESDAY WILL BE CLOUDY AND COOL. RAIN IS ANOTHER QUESTION. THE SYSTEM IS WHOLLY UNIMPRESSIVE. LIMITED LOW LEVEL MOISTURE...ZERO SOUTH FLOW AND SCARCE DYNAMICS. AS ALWAYS THE BEST CHANCE OF RAIN WILL BE OVER THE CENTRAL COAST. THE TROF IS SHOWING SOME SIGNS OF SLOWING SO CARRIED POPS INTO WED MORNING. AT THIS TIME IT LOOKS LIKE THE BEST CHANCE OF RAIN WILL BE ON THE NORTH SLOPES TUESDAY NIGHT. A QUARTER INCH OF RAIN IS THE MOST THIS SYSTEM WILL PRODUCE AND MOST PLACES WILL RECEIVE MUCH LESS. A FAIRLY GOOD NORTH WIND EVENT WILL SET UP TUESDAY NIGHT THE I-5 CORRIDOR WILL BE AFFECTED BY THESE WINDS WHICH WILL BE NEAR ADVISORY CRITERIA. WEDNESDAY WILL BE COOL. CLOUDS WILL BE ON THE DECREASE. TEMPS WILL STILL BE BELOW NORMAL WITH ONLY 560DM HGTS OVERHEAD. .LONG TERM... A NICE LITTLE OFFSHORE EVENT IS SHAPING UP THURSDAY AS A CUT OFF LOW SW OF SAN DIEGO WILL PULL THE UPPER FLOW OFFSHORE TO COMPLEMENT THE BUILDING OFFSHORE SURFACE PRESSURE TREND. RIGHT NOW IT LOOKS LIKE IT WILL COME IN AT LESS THE WAD STRENGTH BUT THE MDLS HAVE BEEN TRENDING IT STRONGER WITH EACH RUN. A WEAK RIDGE WILL BUILD IN OVER THE AREA FRIDAY THROUGH NEXT SUNDAY AND THE WEATHER WILL BE PLEASANT IF A LITTLE DULL. TEMPS WILL RISE TO NEAR NORMAL AND MAYBE A DEGREE OR TWO ABOVE NORMS. && .AVIATION... 19/0930 SIMILAR PATTERN TO YESTERDAY AS STRONG ONSHORE GRADIENTS ARE FORECAST ONE AGAIN. MARINE LAYER CURRENTLY 3000 FT THIS MORNING. EXPECT MVFR CIGS AND VFR/MVFR VSBYS MOST AREAS S OF POINT CONCEPTION TODAY. BURNOFF ACROSS THE VALLEYS SHOULD OCCUR BETWEEN 19-20Z WITH MOSTLY CLOUDY CONDITIONS ACROSS THE COASTAL SECTIONS ONCE AGAIN TODAY. EXPECT LOWER CIGS ACROSS THE CENTRAL COAST AND SALINAS VALLEY AS KSMX AND KSBP SHOULD BE IFR CIGS AND MVFR VSBYS THIS MORNING...WITH BURNOFF NEAR COAST BY 20Z. KPRB SHOULD SEE LIFR CIGS EARLY...THEN BECOMING IFR BY 16Z WITH STRATUS BURNOFF BY 18Z WITH VFR CONDITIONS AFTER THAT. SOME AFTERNOON GUSTY WESTERLY WINDS TO 25 KT ACROSS THE ANTELOPE VALLEY. KLAX...A REPEAT OF YESTERDAY WITH MOSTLY CLOUDY SKIES. MOSTLY MVFR CIGS AND VFR VSBYS WILL PREVAIL THROUGH THE AFTERNOON. WINDS SHOULD BE VARIABLE 6 KT OR LESS THROUGH 17Z...BECOMING SW TO W SEABREEZE BY 18Z WITH STRONGEST SUSTAINED WINDS NEAR 12 KT IN THE AFTERNOON AND EVENING HOURS. KBUR...EXPECT MVFR CIGS AND VFR VSBYS UNTIL 20Z. STRATUS BURNOFF WILL LEAD TO PARTLY CLOUDY SKIES DUE TO THE DEEPNESS OF THE MARINE LAYER. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXCWFLOX). && $$ PUBLIC...RORKE AVIATION...KAPLAN WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
351 AM CDT MON MAR 19 2007 .DISCUSSION REGARDING MORNING ZONES/GRIDS... 351 AM CDT MID LVL TROF AMPLIFYING ACROSS UPR MIDWEST/WRN LAKES THIS MORNING...INDUCING SOME SERIOUS LLVL WAA VIA INTO THE REGION WITH REGIONAL PROFILERS DEPICTING 60-70 KT SWLY FLOW IN 925-850 HPA LAYER. ELEVATED LLVL THETA/E AND MOISTURE CONVERGENCE MAXIMA IN AXIS OF MOIST/UNSTABLE AIR COINCIDENT WITH JET TO TRANSLATE QUICKLY EAST ACROSS SERN HALF OF CWA EARLY THIS MORNING...BEFORE MOVG EAST OF FCST AREA LATER THIS MORNING. THEREFORE CURRENT RADAR DEPICTION OF ELEVATED TRW/RW EXPECTED TO PROGRESS ACROSS AND EVENTUALLY E/SE OF FCST AREA THRU 12-15Z. WILL THUS MAINTAIN CATEGORICAL POPS ACROSS SERN PARTS OF FCST AREA THIS MORNING...AND WILL HOLD ONTO CHC POPS FARTHER NORTHWEST AS SFC COLD FRONT AND MAIN MID LVL S/WV TROF AXIS MOVG THRU MIDDAY. PASSAGE OF THESE FEATURES SHOULD ALLOW SOME CLRG THIS AFTN FROM NW TO SE AS SUBSIDENCE AND LLVL DRY ADVECTION INCREASE IN WAKE OF S/WV. SFC HIGH PRESSURE BUILDS THROUGH NRN GRTLKS TNGT...WITH DRY N/NE LLVL FLOW INTO FCST AREA PROVIDING GENERALLY CLR/COOL WX. SOME POTENTIAL FOR SOME LAKE GENERATED STRATOCU AS COLD POOL PASSES ACROSS LAKE MICH OVRNGT...THOUGH FCST SOUNDINGS INDICATE SUBSIDENCE INVERSION PRETTY FORMIDABLE AND THINK PARTLY CLOUDY CONDITIONS AT WORST NEAR THE BIG POND. SFC HIGH MOVES OFF TO THE EAST ON TUESDAY...WITH LLVL WAA DVLPG ESPECIALLY ALONG/WEST OF MS RIVER AS WEAK AMPLITUDE S/WV TROF PUSHES TOWARD UPPER RIDGE FROM THE WEST. TSECTS REMAIN DRY THRU MID/UPR LEVELS AND SUSPECT LITTLE IN THE WAY OF CLOUD COVER. DESPITE STRONG SUN...COOL EASTERLY FLOW TO LIMIT TEMPS ESPECIALLY NRN IL WITH WINDS OFF LK. NEXT SIG WX APPEARS TO DVLP LATE TUES NGT/WED AS WELL ADVERTISED LARGE SCALE UPPER PATERN SHIFT BEGINS. MID LVL S/WV CONTINUES TO PUSH EAST...WITH LLVL WAA RESPONSE STRENGTHENING OVRNGT. WRF/GFS BOTH DVLP 55 KT 850 JET AHEAD OF APPRCHG WAVE...NOT UNLIKE CURRENT SCENARIO THIS MORNING. WHILE GENERAL IDEA VERY SIMILAR BETWEEN MODEL SIMULATIONS...THERE IS BOUT A 6 HOUR TIMING DIFFERENCE WITH POSN OF WAVE WITH GFS THE FASTER SOLN. DIFFERENCE IS FOR GREATEST PCPN PROB LATE TUES NGT OR DURG MORNING HOURS ON WED. ATTM WILL BLEND WITH CHC LATE TUES NGT AND RAISE POPS A BIT WED MORNING. MODELS THEN IN GOOD AGREEMENT IN MOVG THIS MINOR AMPLITUDE S/WV NORTHEAST OF REGION DURG AFTN HOURS AS SFC WARM FRONT LIFTS INTO FCST AREA WITH WARM/MOIST AIR PUMPING NORTH ON BREEZY SOUTH WINDS. ANOTHER S/WV DEPICTED TO WEST ACROSS PLAINS APPEARS TO SHIFT FOCUS FOR HIGHEST PCPN THREAT BACK ACROSS NEB/WRN IA ALONG WRMFRNT...THOUGH WILL MAINTAIN CHC POPS WED AFTN AS CANT RULE OUT POTENTIAL VCNTY WRMFRNT WHICH MOVES TO IL/WI/SRN LK MICH VCNTY BY 00Z. HAVE RAISED TEMPS WELL INTO 60S FOR WED AFTN GIVEN GOOD LLVL THERMAL ADVECTION. MAIN BRANCH OF WESTERLIES AMPLIFIES ACROSS NRN CONUS WED NGT/THURS BRINING COLD FRONT SAGGING INTO FCST AREA ON THURSDAY. BEST POPS APPEAR TO BE DURG THE DAY THURS AT THIS DISTANCE...THOUGH INCREASING POTENTIAL WEST WED NGT AS FRONT/UPPER WAVE APPROACH. GIVEN DIFFICULTIES OF TIMING SMALLER WAVES HAVE MADE LITTLE CHANGE TO BROAD BRUSH POPS IN THESE LATER PERIODS. RATZER && .AVIATION... 1100 PM CDT THE WARM AIR HAS MOVED IN THE TAF AREA FASTER THAN PREVIOUSLY ANTICIPATED. THE ACARS SOUNDING AT ORD SHOWS THE AIR BELOW 852 METERS LEVEL IS ABOVE FREEZING. THE NEW LOCALLY RUN WRF ARW SHOWS THIS DEPTH OF AIR ABOVE FREEZING TO CLIMB TO 2277 METERS BY 09 UTC. WE CHANGE OUR PRECIPITATION TO RAIN AFTER 06 UTC. THE RADAR SHOWS SOME ECHOES FROM 8000 FEET TO 13000 FEET IN NORTHEAST ILLINOIS. THE SOUNDING AT DVN AT 00 UTC SHOWS THE SATURATED LAYER ABOVE 7905 FT. THERE IS MORE MOISTURE IN THE ATMOSPHERE. THERE HAVE BEEN SOME VERY LIGHT FLURRIES AROUND THE AREA THIS EVENING. WHEN THE MAIN AREA OF PRECIPITATION MOVES IN IT WILL BE MOSTLY RAIN. THE WIND WILL INCREASE IN SPEED SO WE DO NOT EXPECT ANY IFR VISIBILITY. THE CEILING WILL DECREASE TO MVFR CONDITIONS WITH THE LOWEST 1200 BROKEN TO OVERCAST MONDAY MORNING. THE PRECIPITATION IS FORECAST TO END AFTER 1700 UTC WITH THE WIND SHIFT TO THE NORTHWEST AND DRIER AIR MOVING INTO THE TAF AREA. WE USED THE LOCALLY RUN WRF ARW AND WRF MODEL AT NCEP FOR THE SOUNDING FORECASTS AND WIND FORECASTS. && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVSRY THRU TUES MORN. && $$
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
900 AM PDT WED MAR 21 2007 .SYNOPSIS... A TROUGH OF LOW PRESSURE AND DEEP MARINE LAYER WILL BRING CLOUDS AND SHOWERS TODAY FROM THE MOUNTAINS WESTWARD. WEAK TO MODERATE OFFSHORE FLOW WILL DEVELOP TONIGHT AND THURSDAY WITH GUSTY EAST WINDS THROUGH SOME OF THE PASSES. A FEW SHOWERS ARE POSSIBLE AT TIMES TONIGHT THROUGH FRIDAY AS LOW PRESSURE OFF THE NORTHERN BAJA COAST MOVES SLOWLY INLAND ACROSS NORTHERN AND CENTRAL BAJA. FAIR AND WARMER OVER THE WEEKEND UNDER WEAK HIGH PRESSURE. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (TODAY THROUGH FRIDAY)... NEAR STATIONARY UPPER TROUGH EXTENDING SOUTHWEST ACROSS REGION WITH AIR MASS SATURATED TO 10000 FT WILL CONTINUE COOL SHOWERY CONDITIONS TODAY. NORTHERLY JET AROUND 100 KT DROPPING SOUTHWARD ALONG CENTRAL CALIFORNIA COAST HAS BEGUN FORMING A SECONDARY LOW IN THE VICINITY OF POINT CONCEPTION. THIS LOW EXPECTED TO MOVE SOUTH THROUGH TONIGHT AS MODELS HAVE BEEN ADVERTISING. THIS WILL CAUSE FLOW TO SHIFT TO OFFSHORE TONIGHT WITH DRIER AIR MOVING IN FROM THE NORTHEAST. THE MODELS ARE IN AGREEMENT WITH THE LOW TURNING TOWARDS THE EAST ON THURSDAY ALONG 28 N LATITUDE BUT DIFFER ON SPEED OF MOVEMENT. THE SLOWER NAM12 MODEL IS PREFERRED DUE TO THE TENDENCY OF BAROCLINIC MODELS TO EJECT CUTOFF LOWS TOO SOON. THUS PROLONGED PERIOD OF EASTERLY FLOW ACROSS SOUTHWEST CALIFORNIA THURSDAY INTO FRIDAY...WITH THREAT OF WRAP AROUND MOISTURE MOVING ACROSS LOWER DESERTS AND UP AGAINST EAST SLOPES OF MOUNTAINS. THE MAIN THUNDERSTORM THREAT WILL BE TO THE EAST...HOWEVER CLOSE ENOUGH TO THAT A FEW DRY LIGHTNING STRIKES COULD OCCUR IN THE FORECAST AREA...SO WILL LIKELY REINTRODUCE IN THE AFTERNOON FORECAST PACKAGE. && .LONG TERM (SATURDAY THROUGH TUESDAY) FROM PREVIOUS DISCUSSION... HIGH PRESSURE BUILDS INTO CALIFORNIA FROM THE PACIFIC FOR THE WEEKEND...WEAKENING EARLY NEXT WEEK. DGEX SHOWS A RETURN OF THE MARINE LAYER FOR SUNDAY AND MONDAY. EXTENDED MODELS ARE IN BETTER AGREEMENT FOR TUESDAY WITH A FAST MOVING STORM SYSTEM THAT WILL MOVE INLAND ACROSS CALIFORNIA. THIS WILL BRING COOLING AND STRONG GUSTY WINDS IN THE MOUNTAINS AND DESERTS FOR SOUTHWEST CALIFORNIA ALONG WITH A CHANCE OF SHOWERS. && .AVIATION... 211545Z...ACARS SOUNDINGS INDICATE THE MARINE LAYER WAS DISRUPTED THIS MORNING AS DEEP LOW LEVEL MOISTURE REMAINS OVER THE AREA BEHIND A WEAK COLD FRONT THAT MOVED THROUGH EARLY THIS MORNING. MOIST ONSHORE FLOW WILL KEEP LAYERS TO CU AND STRATOCU OVER THE AREA THROUGH THE THIS EVENING WITH MULTIPLE LAYERS BROKEN LAYERS BETWEEN 2500 AND 5000 FEET WITH LOCALLY LOWER LAYERS AROUND 1200 FEET. TOPS ABOVE 8000 FEET. VISIBILITY SHOULD REMAIN VFR EXCEPT FOR MVFR TO LOCAL IFR VISIBILITIES IN VICINITY OF SCATTERED SHOWERS. BROKEN TO OVERCAST STRATOCU SHOULD CONTINUE TONIGHT FROM THE MOUNTAINS WESTWARD WITH BASES AROUND 2500 MSL AND TOPS TO 6000 FEET MSL. GUSTY WESTERLY WINDS ACROSS THE MOUNTAINS WILL PRODUCE MOUNTAIN WAVE/ROTOR ACTIVITY IN THE VICINITY OF KPSP THROUGH THE AFTERNOON. && .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
648 AM CDT WED MAR 21 2007 .DISCUSSION FOR MORNING ZONES/GRIDS... 330 AM CDT FORECAST CONCERN WILL CONTINUE TO BE ON SHOWERS/TSTORMS THROUGH THE WEEKEND...AND THE IMPACT ON AREA RIVERS/STREAMS WHICH ARE CURRENTLY RUNNING HIGH. WATER VAPOR IMAGERY THIS MORNING INDICATING SEVERAL SMALL SCALE SHORT WAVES EMBEDDED IN THE W-SWRLY UPPER LEVEL FLOW. CONVECTIVELY ENHANCED VORT MAX IS CURRENTLY TRACKING ACROSS EASTERN IOWA. MID LEVEL WINDS FROM THE SLATER IOWA PROFILER INDICATED A GOOD VEERING SIGNATURE WITH PASSAGE OF THIS VORT MAX OVER PAST FEW HOURS. STRONGEST ISENTROPIC ASCENT ACROSS NORTHERN ILLINOIS PER THE WRF 295K ISENTROPIC SURFACE WILL CONTINUE THROUGH 12Z IN ADVANCE OF THIS VORT MAX ALLOWING FOR CONTINUED WIDESPREAD SHOWERS THROUGH THE EARLY MORNING HOURS. ELEVATED INSTABILITY IS RATHER LIMITED EARLY THIS MORNING...BECOMING MORE IMPRESSIVE AFTER 12Z ONCE ELEVATED WARM FRONTAL BOUNDARY LIFTS INTO SOUTHERN WISCONSIN. WILL KEEP MENTION OF ISOLD THUNDER THIS MORNING GIVEN THIS. AFTER 12Z...STRONGEST ISENTROPIC UPGLIDE WILL SHIFT NORTHEAST ACROSS EASTERN WISCONSIN/MICHIGAN. ANOTHER UPSTREAM VORT MAX ACROSS EASTERN NEBRASKA IS EXPECTED TO TRACK INTO SOUTHWEST WISCONSIN THIS AFTERNOON. ANOTHER ZONE OF LOW LEVEL ISENTROPIC LIFT/LOW LEVEL THETA-E IN ADVANCE OF THIS VORT MAX IS ALSO CONTRIBUTING TO SHOWER/THUNDERSTORM DEVELOPMENT ACROSS SOUTHERN IOWA/NORTHEAST MISSOURI AT THIS TIME. AS LOW LEVEL WINDS VEER WITH THE PASSAGE OF ELEVATED WARM FRONT THIS MORNING...THIS SHOULD RESULT IN RE-STRENGTHENING LOW LEVEL ISENTROPIC LIFT TOWARD MIDDAY. WITH AFOREMENTIONED NEBRASKA VORT TRACKING INTO SOUTHWEST WISCONSIN...BEST CHANCE OF ADDITIONAL SHOWERS/THUNDERSTORMS MAY BE ACROSS NORTH CENTRAL ILLINOIS. WILL MAINTAIN CHANCE POPS INTO THE AFTERNOON GIVEN THE ABOVE FACTORS. DESPITE CLOUDS/PRECIP TODAY...HIGH TEMPS FROM LOW 60S EXTREME NORTH TO UPPER 60S SOUTH STILL SEEM REASONABLE GIVEN EXPECTATION THAT SURFACE WARM FRONTAL BOUNDARY WILL TRACK INTO SOUTHERN WISCONSIN THIS AFTERNOON WITH SFC DEW PTS RISING INTO THE 50S. FOR TONIGHT...BREEZY S-SW WINDS IN WARM SECTOR WILL ALLOW FOR A MINIMAL TEMP DROP OFF AND MAIN CONCERN WILL BE ON RENEWED CHANCES FOR SHOWERS/STORMS AS RATHER VIGOROUS NORTHERN STREAM SHORT WAVE TROUGH MOVES ALONG THE US/CANADIAN BORDER DRIVING A COLD FRONT SOUTHEASTWARD. TREND OVER PAST FEW RUNS OF WRF/GFS HAVE BEEN TO A FASTER FRONTAL TIMING ACROSS NORTHWEST ILLINOIS LATE WEDNESDAY NIGHT. GIVEN PROGRESSIVE NATURE OF THIS NORTHERN STREAM TROUGH...HAVE GENERALLY BOUGHT INTO THIS IDEA. THUS...HAVE MOVED UP TIMING OF SHOWERS/THUNDERSTORMS FOR TONIGHT...AND NOW QUICKER TO LOWER POPS FROM NORTHWEST TO SOUTHEAST DURING THE DAY THURSDAY. ELEVATED INSTABILITY IS MORE IMPRESSIVE TONIGHT INTO EARLY THURSDAY WITH WRF BUKFIT SOUNDINGS INDICATING 500-1000 J/KG OF ELEVATED INSTABILITY OVERNIGHT WITH A 60 KT SWRLY LLJ. DOES NOT SEEM LIKE AN OPTIMAL SEVERE SETUP GIVEN FRONTAL TIMING BUT CANNOT RULE OUT GUSTY WINDS/SMALL HAIL LATE TONIGHT NORTH OF I-88. WITH THE FRONT PUSHING ACROSS THE AREA THURSDAY MORNING...BETTER CHANCE OF AFTERNOON THUNDER/LIMITED SEVERE POTENTIAL LOOKS TO SET UP SOUTH OF THE AREA. OF GREATER SIGNIFICANCE WILL BE RAINFALL TOTALS. BETWEEN RAINFALL TONIGHT AND ON THURSDAY...TOTAL RAINFALL AMOUNTS OF 1 TO 2 INCHES ARE POSSIBLE. WILL CONTINUE TO HOLD OFF ON HYDRO HEADLINES GIVEN RAINFALL RATES NOT EXCEEDINGLY GREAT THIS MORNING...BUT SOME MINOR FLOODING PROBLEMS WILL LIKELY PERSIST ON PORTIONS OF THE KANKAKEE RIVER IN NORTHWEST INDIANA. TEMPS WERE CHANGED VERY LITTLE THIS WEEKEND INTO EARLY NEXT WEEK...ALTHOUGH DID LOWER MAX TEMPS BELOW GUIDANCE FRIDAY JUST A SHADE. NORTHEAST FLOW UNDER INFLUENCE OF SURFACE HIGH AND LINGERING FRONTAL INVERSION SHOULD ALLOW FOR TEMPS TO ONLY STRUGGLE INTO THE LOW TO MID 50S ACROSS FAR NORTHERN ILLINOIS WITH COOLER LAKESIDE TEMPS. PRECIP FORECAST FROM THURSDAY NIGHT-SATURDAY GETS A BIT TRICKER WITH SFC HIGH SETTLING OVER THE SOUTHERN GREAT LAKES AND LOW LEVEL BOUNDARY STALLING OUT SOUTH OF THE AREA. GIVEN UNCERTAINTY...HAD TO MAINTAIN CHANCE POPS ACROSS THE FAR SOUTH THROUGH THE EARLY PART OF THE WEEKEND. CHANCE POPS FOR TSRA RETURN CWA-WIDE SUNDAY-TUESDAY AS CUT OFF UPPER LOW ACROSS SOUTHWEST CONUS SLOWLY BEGINS TO LIFT INTO THE PLAINS. MARSILI && .AVIATION DISCUSSION REGARDING 06Z TAFS... 648 AM CDT FORECAST FOCUS REMAINS TIMING PRECIP/CONVECTIVE THREATS TO TERMINALS...AS WELL AS ASSOCIATED IFR CIG/VIS ISSUES THIS MORNING. SERIES OF MINOR AMPLITUDE MID LVL S/WV TROFS RIPPLING NE FROM CENTRAL/SRN PLAINS TODAY RESULTING IN RW/EMBEDDED TRW AFFECTING MS VLY AND WRN GRTLKS REGION IN BROAD SWLY MOIST/WARM ADVECTION. VAPOR IMAGERY INDICATES ONE WEAK VORT LIFTING NERN IL/SERN WI ATTM...WITH ANOTHER WELL DEFINED SMALL S/WV MOVG INTO WRN IA. PROFILERS/ACARS SOUNDINGS DEPICT 50 KT LLVL JET IMPINGING UPON ELEVATED WARM FRONTAL ZONE...PRODUCING MOIST CONVERGENCE/THETA-E ADVECTION INTO FCST AREA. ACARS SOUNDINGS FROM KDSM AND KRFD INDICATE LAPSE RATES NOT VERY STEEP...THOUGH TS OCCURRING ALONG ELEVATED MOIST CONVERGENT AXIS FROM NERN IA TO ECNTRL MO/WCNTRL IL. S/WV TO LIFT THRU FCST AREA DURG THE MORNING/EARLY AFTN HOURS...THOUGH EXPECT SOME DIURNAL DECREASE TO LLVL JET STRENGTH AND WEAKENING OF RW/TRW BY MID/LATE MORNING. KRFD HAS PERHAPS BETTER CHANCE OF TRW...GIVEN BETTER MID LEVEL FORCING AS WRN IA S/WV LIFTS INTO WI. IFR CIGS WHICH HAVE DVLPD IN RAIN MOISTENED COOLER LOW LEVELS SHOULD IMPROVE TO MVFR LATER THIS MORNING AS RW DECREASE AND TEMPS RISE. WITH S/WV LIFTING NORTHEAST OF AREA XPCT TO HAVE LULL IN PCPN THREAT FROM AFTN THRU EVENING HOURS...THEN THREAT INCREASES OVRNGT AS MORE AMPLIFIED UPPER TROF MOVES ACROSS NRN PLAINS/UPR LAKES. FCST SOUNDINGS INDICATE GREATER INSTABILITY AHEAD OF FRONT TONIGHT AS UPPER FORCING INCREASES...600-700 J/KG OF MLCAPE FOR A PARCEL JUST ABOVE BOUNDARY LAYER. THUS EXPCTG LINE OF TS TO MOVE RAPIDLY EAST ACROSS FCST AREA AHEAD OF COLD FRONT AFTER MIDNIGHT TNGT. SFC WINDS WHICH HAVE BEEN PRETTY STEADY IN 130-150 DEG RANGE SHOULD GRADUALLY VEER SOUTH WITH TIME AS SFC WRMFRNT LIFTS NORTH ACROSS AREA THRU AFTN. FCST SOUNDINGS CONTINUE TO INDICATE POTENTIAL FOR GUSTINESS INTO 25+ KT RANGE FROM LATE AFTN INTO THE OVRNGT HOURS...AS WINDS BECOME MORE SSW WITH TIME. COLD FROPA APPEARS TO AFFECT KRFD AROUND 10-11Z...THEN INTO CHI AREA ABOUT 12/13Z. 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 SAN DIEGO CA
200 PM PDT WED MAR 21 2007 .SYNOPSIS... A LOW PRESSURE SYSTEM OVER THE OUTER WATERS WILL MOVE SLOWLY SOUTH TONIGHT. SHOWERS SHOULD DIMINISH OVER NIGHT. WEAK TO MODERATE OFFSHORE FLOW WILL DEVELOP TONIGHT AND THURSDAY WITH GUSTY EAST WINDS THROUGH SOME OF THE PASSES. A FEW THUNDERSTORMS ARE POSSIBLE THURSDAY AND FRIDAY OVER THE MOUNTAINS AND DESERTS AS LOW PRESSURE MOVES SLOWLY EAST ACROSS CENTRAL BAJA CALIFORNIA. FAIR WEATHER IS EXPECTED FOR THE WEEKEND AS HIGH PRESSURE MOVES OVER CALIFORNIA. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (TONIGHT THROUGH FRIDAY)... AIR MASS CURRENTLY SATURATED AND UNSTABLE...BUT WITH CUTOFF LOW NOW SPUN UP AND MOVING SOUTH OVER OUTER WATERS PER MODEL FORECAST...AS THE LOW PULLS FURTHER AWAY FROM COAST TONIGHT...DRYING AND STABILIZING EXPECTED TO TAKE PLACE AS LOW AND MID LEVEL FLOW SHIFTS TO OFFSHORE AND WARM AIR ADVECTION TAKES PLACE ALOFT. THE MODELS TAKE THE LOW SOUTH TO ABOUT 28N LATITUDE BEFORE TURNING IT EASTWARD AND TRACKING IT SLOWLY ACROSS NORTH CENTRAL BAJA CALIFORNIA. BOTH GFS AND NAM12 NOW IN AGREEMENT ON SPEED OF MOVEMENT WITH LOW NOT MOVING OVER GULF OF CALIFORNIA AND INTO SONORA MEXICO UNTIL LATE FRIDAY. AT THIS SPEED SOUTHWEST CALIFORNIA WILL BE UNDER MODERATE EASTERLY FLOW THROUGH FRIDAY...WITH GUSTS AROUND 40 MPH THROUGH PASSES AND CANYONS. WEST OF THE MOUNTAINS A DRYING AND WARMING TREND IS EXPECTED...AND DAYTIME TEMPERATURES WERE INCREASED TO O SHOW 5-10 DEGREES WARMING EACH DAY. EASTERN HALF OF THE AREA WILL ALSO BE WARMING BUT TEMPERED SOMEWHAT BY CONTINUED CLOUD COVER DUE TO WRAP AROUND MOISTURE. ALSO UPSLOPE FLOW AND WARMER DAYTIME TEMPERATURES WILL ADD TO THE LINGERING INSTABILITY THERE AND MAY RESULT IN THUNDERSTORM SO INCLUDED MENTION OF AFTERNOON THUNDERSTORMS/DRY LIGHTNING OVER LOWER DESERTS AND EASTERN HALF OF MOUNTAINS FOR THURSDAY AND FRIDAY. && .LONG TERM (SATURDAY THROUGH WEDNESDAY)... HIGH PRESSURE RIDGE MOVES SOUTHEAST ACROSS CALIFORNIA ON SATURDAY AND FLATTENS SUNDAY. THIS SHOULD RESULT IN A GENERAL WARMING AND DRYING TREND INLAND...HOWEVER COASTAL EDDY EXPECTED TO DEVELOP AND DEEPEN MARINE LAYER SO COAST AND LOWER INLAND VALLEYS WILL BE COOLING AND MOISTENING. ON MONDAY AND TUESDAY...TROUGH/COLD FRONT MOVING INLAND TO THE NORTH WILL BRING COOLING ALL AREAS AS WELL AS INCREASE WEST TO SOUTHWEST WINDS OVER MOUNTAINS AND DESERT AND BRING ANOTHER CHANCE FOR PRECIPITATION. COOL BUT DRY NORTHWEST FLOW EXPECTED ON WEDNESDAY AS WEAK RIDGE BUILDS IN BEHIND DEPARTING TROUGH. && .AVIATION... 211930Z...LATE MORNING ACARS SOUNDINGS ARE BEGINNING TO SHOW A HINT OF A MARINE INVERSION AROUND 8000 FEET. MOIST ONSHORE FLOW WILL KEEP BROKEN LAYERS OF STRATOCU OVER THE AREA THROUGH THE NIGHT WITH HEIGHTS RANGING FROM AROUND 2500 FEET MSL TO 6000 FEET MSL. LOCALLY LOWER SCATTERED TO BROKEN LAYER AROUND 1500 FEET MSL. FOR THURSDAY...WRAP AROUND MOISTURE ASSOCIATED WITH UPPER LOW OFF THE COAST OF NORTHERN BAJA WILL KEEP LAYERS TO STRATOCU AND ALTOCU OVER THE AREA THROUGH THE AFTERNOON. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC/FIRE WEATHER...BALFOUR AVIATION/MARINE.......HORTON NWS ON THE WEB AT WEATHER.GOV/SANDIEGO