Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 03/22/07

AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
430 AM PDT TUE MAR 20 2007 .SYNOPSIS... A DEEP MARINE LAYER AND ONSHORE FLOW WILL CAUSE LOW CLOUDS...LOCAL FOG AND DRIZZLE WEST OF THE MOUNTAINS THIS MORNING. UPPER LEVEL LOW PRESSURE WILL BRING VARIABLE CLOUDINESS AND SMALL CHANCES OF MAINLY LIGHT PRECIPITATION AT TIMES THROUGH FRIDAY. THERE MAY ALSO MAY BE A PERIOD OF MODERATE OFFSHORE FLOW WEDNESDAY NIGHT AND THURSDAY. FAIR AND A LITTLE WARMER NEXT WEEKEND UNDER WEAK HIGH PRESSURE. SPRING BEGINS TODAY AT 507 PM PDT. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (TODAY THROUGH THURSDAY)... A TROUGH OF LOW PRESSURE WILL MOVE INLAND ALONG THE CENTRAL CALIFORNIA COAST TODAY. THOUGH NOT IN PERFECT AGREEMENT...MODELS THEN GENERALLY TAKE THIS UPPER TROUGH AND DEVELOP A CLOSED UPPER LOW THAT DRIFTS SLOWLY SOUTHWARD OFF THE SOUTHERN CALIFORNIA AND NORTHERN BAJA COASTS TONIGHT THROUGH THURSDAY. FOR THIS MORNING...A DEEP MARINE LAYER CONTINUES WEST OF THE MOUNTAINS WITH A RECENT ACARS SOUNDING FROM ONT SHOWING THE DEPTH NOW GREATER THAN 5000 FEET. PATCHY DRIZZLE IS POSSIBLE ALONG THE WEST OF THE MOUNTAINS THIS MORNING FROM THIS DEEP MARINE LAYER. SATELLITE IMAGERY ALSO SHOWS A SHORTWAVE TO THE SOUTHWEST ENHANCING MID LEVEL CLOUDINESS OFF THE SOUTHWEST CALIFORNIA AND NORTHERN BAJA COAST. THIS COULD BRING SOME LIGHT PRECIPITATION TO SOUTHWEST CALIFORNIA AT TIMES TODAY...MAINLY ALONG AND WEST OF THE MOUNTAINS. AS THIS LOW CLOSES OFF...THE CHANCE OF MAINLY LIGHT PRECIPITATION WILL CONTINUE ALONG AND WEST OF THE MOUNTAINS THROUGH WEDNESDAY MORNING. DEPENDING UPON THE TRACK AND POSITION OF THE UPPER LOW...THERE COULD BE A PERIOD OF MODERATE OFFSHORE LATE WEDNESDAY NIGHT THROUGH THURSDAY. PRECIPITATION CHANCES MAY DECREASE SOME WEDNESDAY NIGHT THROUGH EARLY THURSDAY...BUT REMAIN DEPENDENT ON THE TRACK OF THE UPPER LOW. && .LONG TERM (FRIDAY THROUGH MONDAY)... FOR THURSDAY NIGHT AND FRIDAY...MODELS CONTINUE TO SHOW SOME POTENTIAL FOR MORE SIGNIFICANT "WRAP AROUND" PRECIPITATION TO SPREAD INTO FAR SOUTHERN SECTIONS OF SOUTHERN CALIFORNIA AS THE UPPER LOW MOVES INLAND ACROSS NORTHERN AND CENTRAL BAJA. WILL CONTINUE SLIGHT CHANCE AND CHANCE POPS WITH HIGHEST POPS SOUTH. FOR THE WEEKEND...WEAK HIGH PRESSURE WILL BRING FAIR AND A LITTLE WARMER WEATHER WITH GREATEST WARMING INLAND. FOR EARLY NEXT WEEK...A STRONGER TROUGH OF LOW PRESSURE MOVING INLAND ALONG THE CALIFORNIA COAST SHOULD BRING COOLING...STRONG GUSTY WINDS IN THE MOUNTAINS AND DESERTS...AND ANOTHER CHANCE OF PRECIPITATION. SOME MODEL SPREAD IN THE TIMING AND INTENSITY...BUT GENERALLY CENTERED ON TUESDAY FOR THE MAIN IMPACT ON SOUTHWEST CALIFORNIA. && .AVIATION... 201120Z...THICK LOW OVERCAST STRATUS WILL CONTINUE TO COVER ALL AREAS WEST OF THE MOUNTAINS THROUGH 20Z WITH BASE AROUND 2500 FT MSL AND TOPS NEAR 4000 FEET. SPOTTY DRIZZLE POSSIBLE. INCREASED ONSHORE FLOW AHEAD OF AN UPPER LEVEL TROUGH WILL BRING INCREASING WEST WINDS THIS AFTERNOON. MOIST FLOW ALOFT WILL CAUSE INCREASING 10K FT ALTOSTRATUS THROUGH THE DAY. A BROKEN LAYER OF 4000 FT STRATOCU WITH ISOLATED TO SCATTERED LIGHT SHOWERS WILL COVER THE AREA LATE THIS AFTERNOON THROUGH WEDNESDAY AS A WEAK TROUGH SETTLES OVER SOUTHERN CALIFORNIA. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...MARTIN AVIATION/MARINE...MACKECHNIE NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
320 AM PDT TUE MAR 20 2007 .SHORT TERM... FORECAST CONFIDENCE HAS DETERIORATED CONSIDERABLY SINCE YDY. VERY WEAK AND DIFFUSE FRONT APPROACHING THE BAY AREA NOW. IT WILL REACH THE CENTRAL COAST THIS AFTERNOON AND AREAS SOUTH OF POINT CONCEPTION LATER THIS AFTERNOON AND EVENING. HOW WELL THE FRONT HOLDS TOGETHER IS SOMEWHAT OF A PUZZLE. GFS IS THE MORE ROBUST MDL BUT 06Z WRF HAS TRENDED A LITTLE WETTER. ACARS SHOWS MARINE LAYER AT 2500 FEET AND WITH A 6 PLUS MB ONSHORE PUSH CLOUDS AGAIN COVER ALL COASTS AND VLYS AND EXTEND DEEP INTO THE MOUNTAIN PASSES. THERE WILL BE A CHANCE OF SOME DRIZZLE IN THE FOOTHILLS AND MOUNTAINS. WHILE ASSIGNING THE EXACT POP VALUE TO THE RAIN IS DIFFICULT FORECASTING THE AMOUNT OF RAIN POTENTIAL IS NOT SINCE THIS IS A FAIRLY DRY AND UNINSPIRED SYSTEM AT MOST A QUARTER INCH WILL FALL AND MORE LIKELY A TENTH. AS USUAL THE CENTRAL COAST WILL HAVE BOTH THE GREATEST CHANCE OF RAIN AS WELL AS THE GREATEST POTENTIAL FOR THE MOST RAINFALL. THE UPPER TROF MOVES OVERHEAD TONIGHT AND WILL BRING A CHANCE OF RAIN WITH IT...ALTHOUGH THE CHANCES FOR THE CENTRAL COAST WILL DIMINISH AFTER EVENING. WEDNESDAY THE UPPER TROF DOES NOT PROGRESS RATHER IT IS FORECAST TO PINCH OFF INTO AN UPPER LOW AND PLUNGE QUICKLY SOUTHWARD. WHAT THIS SCENARIO WILL DO IS SOMEWHAT HARD TO PREDICT, IT LOOKS LIKE THERE WILL BE ENOUGH WRAP AROUND AND DYNAMICS FOR A FURTHER CHANCE OF SHOWERS SOUTH OF POINT CONCEPTION...IF THE UPPER LOW MOVES A LITTLE SLOWER IT WILL INCREASE THE POTENTIAL FOR THUNDERSTORMS AND THIS WILL HAVE TO BE WATCHED. UNDERNEATH THE UPPER LOW LOW LEVEL NORTH FLOW WILL BUNCH CLOUDS UP ALONG THE NORTH SLOPES AND ALSO CREATE A SLIGHT CHANCE OF SHOWERS THERE. THINGS SHOULD CLEAR OUT WEDNESDAY AFTERNOON AS THE LOW MOVES FURTHER SOUTH AND OUT OF REACH OF THE LOX CWA. AS THE LOW SLIDES SOUTH IT ALSO TURNS THE UPPER LEVEL FLOW OFFSHORE. COINCIDENT WITH THIS IS A HIGH MOVING INTO THE GREAT BASIN. BOTH OF THESE WILL COMBINE TO PRODUCE A DECENT OFFSHORE EVENT. IF THINGS GO AS PLANNED WIND ADVISORIES WILL BE NEEDED IN THE MOUNTAINS AND SOME VALLEY LOCATIONS. .LONG TERM... DRY NORTHWEST FLOW TURNS INTO A WEAK RIDGE SATURDAY. FLOW TURNS ONSHORE SO WHILE MOST AREAS WILL WARM EACH DAY THE COASTAL AREAS WILL COOL OR REMAIN ABOUT THE SAME. THE ONSHORE FLOW INCREASES SAT NIGHT AND THE RIDGE SHOULD PROVIDE ENOUGH WARMING ALOFT TO CREATE A DECENT MARINE LAYER SUNDAY. BOTH THE GFS AND EC INDICATE SOME SORT OF STORM ACTIVITY NEXT MON OR TUE. THE EC IN FACT LOOKS PRETTY DECENT ON TUESDAY. TIME WILL TELL HOWEVER ON THIS THE DRIEST YEAR TO DATE AND FOR NOW INCREASED THE CLOUDS AND COOLED THE TEMPS. && .AVIATION... 20/1140 MORNING MARINE LAYER DEPTH RUNNING AROUND 3000-3500 FT...BUT WITH SOMEWHAT DISORGANIZED AREAL PATTERN AS CLOUDS SOCKED IN OVER COASTAL AND VALLEY SECTIONS OF SLO/SBA/VTU COUNTIES BUT LIMITED COVERAGE OVER LAX COUNTY. OVERALL...EXPECT CEILINGS AT ALL COASTAL/COASTAL VALLEY TAFS SITES THIS MORNING WITH CEILING HEIGHTS BETWEEN 2500 AND 3500 FT WHILE VSBYS REMAIN AT 4 MILES OR ABOVE. WITH APPROACHING WEAK FRONTAL SYSTEM PROGGED TO MOVE ACROSS THE AREA TODAY AND TONIGHT... EXPECT MVFR/VFR CEILINGS TO CONTINUE ACROSS THE AREA THROUGH THE EVENING HOURS. ONSHORE FLOW WILL PRODUCE STANDARD ONSHORE WINDS THROUGH THIS AFTERNOON...WITH SOME NORTHWEST/NORTH EXPECTED TONIGHT BEHIND THE FRONT. THESE WINDS COULD CAUSE SOME WIND SHEAR PROBLEMS ESPECIALLY OVER KSBA. AS FOR ACTUAL PRECIP...CHANCES ARE RATHER LOW...20-30% THROUGH TONIGHT. SO...WILL NOT HIT PRECIP THAT HARD IN THE 12Z TAFS. FOR KLAX...EXPECT CEILINGS AROUND 3500 FT THROUGH THE AFTERNOON WITH A SLIGHT CHANCE OF SHOWERS IN THE AFTERNOON. LIGHT WINDS THIS MORNING WILL GIVE WAY TO A SOUTHWEST WINDS 10-15 KTS THIS AFTERNOON AND EVENING. FOR KBUR...EXPECT CEILINGS AROUND 2500 FT THIS MORNING...RISING TO AROUND 3500 FT THIS AFTERNOON AND EVENING WITH A SLIGHT CHANCE OF SHOWERS. A 6-10 KT SOUTHERLY SEA BREEZE IS EXPECTED THIS AFTERNOON. DEVELOPING NORTHERLY FLOW BEHIND FRONT COULD PRODUCE SOME WIND SHEAR PROBLEMS WHICH FUTURE SHIFTS WILL HAVE TO MONITOR. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXCWFLOX). && $$ PUBLIC...RORKE AVIATION...THOMPSON WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
645 AM CDT TUE MAR 20 2007 .DISCUSSION REGARDING MORNING ZONES/GRIDS... 330 AM CDT MAIN FORECAST CONCERNS WILL BE ON TEMPERATURES AND PERIODIC CHANCES OF SHOWERS/TSTORMS FROM TONIGHT THROUGH THURSDAY...AND THEN AGAIN FOR THE LATTER PART OF THE WEEKEND. SFC ANTICYCLONE CENTERED ACROSS SOUTHERN ONTARIO THIS MORNING WILL CONTINUE TO TRACK OFF TO THE EAST TODAY ALLOWING FOR WINDS TO CONTINUE TO VEER MORE EASTERLY THIS AFTERNOON. EASTERLY FLOW...WEAK LOW LEVEL THERMAL ADVECTION...AND FAIRLY LOW BASED SUBSIDENCE INVERSION WILL ALLOW FOR COOLER CONDITIONS TODAY. MIXING MODEL 950 HPA TEMPS TO THE SURFACE YIELDS HIGHS FROM UPPER 40S NORTH TO LOWER 50S SOUTH. GIVEN FULL SUN TODAY...MAY SEE TEMPS EVEN A LITTLE WARMER THAN THIS. MID LEVEL WARM ADVECTION CLOUDINESS ACROSS EASTERN DAKOTAS/WESTERN MINNESOTA SHOULD TRACK MAINLY ACROSS NORTHERN WISCONSIN TODAY WHILE LOW CLOUDS FROM THE CENTRAL PLAINS AND LOWER MS RIVER VALLEY ONLY SLOWLY NUDGE NORTHWARD TODAY. ANOTHER STRONG LOW LEVEL JET TONIGHT WILL ALLOW FOR NORTHWARD SURGE TO LOW LEVEL WARM FRONT CURRENTLY ACROSS THE SOUTHERN PLAINS WHERE SFC DEW PTS ARE IN THE UPPER 50S TO LOWER 60S. AN UPPER LEVEL SHORT WAVE ALSO EVIDENT ON WATER VAPOR IMAGERY EARLY THIS MORNING ACROSS THE TEXAS PANHANDLE WILL ALSO TRACK NORTHEAST INTO CENTRAL ILLINOIS BY LATER TONIGHT. ALTHOUGH SOME DISCREPANCIES HAVE EXISTED FROM PREVIOUS MODEL RUNS IN REGARDING TO EXACT TRACK OF THIS VORT MAX...THERE HAS BEEN GENERALLY SOME GOOD RUN TO RUN CONTINUITY WITH THIS FEATURE. STRONG POSITIVE LOW LEVEL THETA-E/MOISTURE ADVECTION WITH THIS LOW LEVEL JET WILL TAKE 850 HPA DEW PTS BACK INTO THE +7 TO +10 DEG CELSIUS RANGE AFTER 06Z WITH PWATS INCREASING TO AROUND 1.25 INCHES OVERNIGHT. MID LEVEL LAPSE RATES/ELEVATED INSTABILITY DO NOT LOOK OVERLY IMPRESSIVE TONIGHT. TAKING A PARCEL BASED FROM 900 HPA IN GFS/WRF FORECAST SOUNDINGS ONLY YIELDS 50-100 J/KG OF ELEVATED INSTABILITY. HOWEVER GIVEN STRENGTH OF LOW LEVEL THETA-E ADVECTION/ISENTROPIC LIFT WILL CONTINUE TO MENTION THUNDER. CURRENT TIMING OF SHOWERS AND THUNDERSTORMS OVERSPREADING THE AREA STILL LOOKS GOOD...POSSIBLY BY LATE IN THE EVENING IN THE FAR SOUTHWEST...AND AFTER MIDNIGHT ACROSS THE REMAINDER OF THE FORECAST AREA. MIN TEMPS TONIGHT WILL BE REACHED IN THE EVENING...WITH SLOWLY RISING TEMPERATURES OVERNIGHT. SHOWERS/STORMS WILL LIKELY EXIT THE AREA BY MIDDAY WEDNESDAY BUT WILL MAINTAIN LOWER CHANCE POPS FOR TSRA WEDNESDAY AFTERNOON WITH CWA ESTABLISHED IN WARM SECTOR. THE PRIMARY INSTABILITY AXIS WILL REMAIN OFF TO THE WEST THROUGH THE DAY WEDNESDAY AS NORTHERN STREAM WAVE TRACKS THROUGH THE GREAT BASIN AND SOUTHERN STREAM UPPER LOW GETS CUT OFF JUST OFF THE SOUTHERN CALIFORNIA COAST. DID NOTCH TEMPS UP A BIT FOR WEDNESDAY...WITH HIGHS GENERALLY IN THE MID TO UPPER 60S AND SFC DEW PTS WELL INTO THE 50S. SHOWERS AND THUNDERSTORMS EXPECTED AGAIN LATE WEDNESDAY NIGHT INTO THURSDAY AS FRONTAL BOUNDARY ASSOCIATED WITH AFOREMENTIONED NORTHERN STREAM VORT APPROACHES WESTERN PORTIONS OF THE FORECAST AREA BY THURSDAY MORNING. MOST IMPRESSIVE INSTABILITY THROUGH THE FORECAST PERIOD WILL BE LATE WEDNESDAY NIGHT INTO THURSDAY JUST AHEAD OF THIS FRONTAL BOUNDARY. UPPER SUPPORT ALSO BECOMES STRONGER WITH MODELS INDICATING 120 KT UPPER SPEED MAX CUTTING THROUGH THE WESTERN LAKES WITH LOT CWA IN A FAVORABLE PROXIMITY TO RIGHT ENTRANCE REGION OF THIS JET. DID CONTEMPLATE ISSUING FLOOD WATCH FOR THESE TWO PERIODS OF ENHANCED PRECIP...BUT CONFIDENCE IN TRYING TO PEG AREAS OF BEST RAINFALL ON THURSDAY SEEMS A BIT TRICKY AT THIS TIME. OVERNIGHT CONVECTION MAY TEND TO WEAKEN THURSDAY MORNING ACROSS NORTHWEST/NORTH CENTRAL ILLINOIS AND INTENSIFY AGAIN THURSDAY AFTERNOON ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA. WILL NEED TO MONITOR THE SITUATION HOWEVER WITH SOME HIGH WATER LEVELS ON AREA RIVERS. NO CHANGES TO THE EXTENDED PORTION OF THE FORECAST...GFS INDICATING NORTHWARD RETURN OF WARM FRONT LATE SATURDAY BUT OTHER MEDIUM RANGE MODELS SUPPORT SLOWER EVOLUTION OF INGESTING SOUTHWEST CONUS UPPER LOW SO HAVE SIDED WITH CONSENSUS AND KEPT MOST OF CWA DRY SATURDAY...WITH RETURN OF CHANCE POPS FOR TSRA ON SUNDAY. MARSILI && .AVIATION... 645 AM CDT SFC HIGH PRESSURE CONTINUES TO BUILD SOUTHEAST ACROSS ONTARIO THIS MORNING...PRODUCING COOL NORTHEASTERLY LLVL FLOW INTO FORECAST AREA. SOME MVFR STRATOCU DVLPG OFF OF LAKE MICHIGAN LAST COUPLE OF HOURS...IN SHALLOW MIXED LAYER BENEATH SIGNIFICANT SUBSIDENCE INVERSION SEEN JUST BELOW 900 HPA IN ACARS SOUNDINGS OUT OF KORD. FCST SOUNDINGS SUGGEST THIS TO BE A FAIRLY SHORT LIVED NUISANCE THIS MORNING...AS INVERSION LOWERS A BIT MORE. HOWEVER...WILL HAVE TO CARRY A FEW HOURS OF SCT/TEMPO BROKEN MVFR FOR KORD/KMDW AND KDPA. SOME GUSTINESS TO NORTHEAST WINDS EARLY THIS MORNING TOO...WITH COMBINATION OF LLVL CAA...SFC PRESSURE RISE MAXIMA AND TIGHTER PRES GRADIENT ON SOUTHERN PERIPHERY OF ANTICYCLONE. WIND EXPECTED TO SHIFT MORE EASTERLY WITH TIME DURG THE DAY...WITH GUSTS SUBSIDING BY LATE MORNING AS GRADIENT RELAXES AND SUBSIDENCE INVERSION LIMITS MIXING DEPTH. GRADIENT WINDS BECOME SOUTHEAST THIS EVENING IN 10-15 KT RANGE. NEXT CONCERN PRESENTS ITSELF TONIGHT...AS S/WV TROF LIFTS FROM SOUTHERN PLAINS AND INDUCES LLVL MOIST/WARM ADVECTION OVER BAROCLINIC ZONE TO OUR SOUTH. FROM TIMING PERSPECTIVE...APPRCHG S/WV AND MOISTURE CONVERGENCE ON 40-50 KT LLVL JET FOCUS BEST FORCING INTO FCST AREA TOWARD 12Z AS WARM FRONT LIFTS TOWARD NRN IL/NWRN IND. FCST SOUNDINGS DO NOT INDICATE SIGNIFICANT ELEVATED INSTABILITY...WITH BUFKIT ANALYSIS OF BOTH WRF/GFS SOUNDINGS DEPICTING LESS THAN 100 J/KG STARTING AT AROUND 900 HPA. THUS ATTM FEEL POINT PROB FOR THUNDER AT ANY GIVEN TERMINAL LOCATION IS PRETTY LOW...THOUGH DO SUSPECT SOME ISOLATED THUNDER ACROSS THE FCST AREA. THUS WILL NOT INCLUDE THUNDER RIGHT NOW...THOUGH WILL INDICATE CB CLOUD TYPES AFTER 08Z OR SO WITH TEMPO SHOWERS. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVSRY THROUGH NOON ALL NEARSHORE ZONES. && $$
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
932 AM CDT TUE MAR 20 2007 .DISCUSSION... 12Z CRP/LCH SOUNDINGS SHOW A MOIST LAYER IN THE LOW LEVELS TRAPPED BETWEEN A SIGNIFICANT CAP IN THE 700-800 MB LAYER. ACARS SOUDINGS SHOW WEAKER CAPPING IN THE LOW LEVELS. CRP SOUDING SHOWED A PW OF 1.31 INCHES. WATER VAPOR IMAGERY SHOWS A WEAK SHORTWAVE NEAR THE RIO GRANDE WHICH MODELS BRING ACROSS SE TX THIS EVENING. THINK WE COULD SEE SOME SPRINKLES OR A FEW LIGHT SHOWERS THIS AFTN/TONIGHT AS THIS SHORTWAVE AFFECTS THE AREA AND HAVE ADDED 20 POPS TO THE FCST. WITH INCREASED CLOUD COVER TODAY...TEMPS SHOULD BE A COUPLE OF DEGREES COOLER THAN YESTERDAY. NO SIGNIFICANT CHANGES TO THE REST OF THE FORECAST. && .PREV DISCUSSION... /ISSUED 309 AM CDT TUE MAR 20 2007/ DISCUSSION...SATELLITE IMAGES AND NAM40 500MB HEIGHT ANALYSIS INDICATED ANOTHER WEAK SHORTWAVE TROUGH MOVING ACROSS CENTRAL TEXAS THIS MORNING. RADAR IMAGES INDICATE NO CONVECTION WITH THIS FEATURE AND WITH MOISTURE CONFINED TO BELOW 850MB...RAIN CHANCES APPEAR LIMITED WITH AN INVERSION AT 850MB KEEPING A CAP ON SHOWERS DEVELOPING TODAY. THE MODELS ARE FAIRLY CONSISTENT WITH THESE WEAK SHORTWAVE TROUGHS MOVING ACROSS THE STATE THE NEXT COUPLE OF DAYS AS A TROUGH DEVELOPS ACROSS THE WESTERN UNITED STATES TODAY. THE 500MB TROUGH ACROSS THE WESTERN U.S. IS PROGGED TO CUT OFF AS A LOW ACROSS SOUTHERN CALIFORNIA/NORTHERN BAJA CALIFORNIA WEDNESDAY AND DRIFT SOUTHWARD THURSDAY. THIS WILL ALLOW A SHORTWAVE RIDGE TO DEVELOP ACROSS SOUTH TX WEDNESDAY AND PERSIST ACROSS EAST TX THURSDAY. THIS FEATURE SHOULD KEEP MOST OF THE CONVECTION WELL TO THE NORTH AND WEST OF THE CWA THROUGH THE REST OF THE WEEK. AS THE 500MB LOW ACROSS NORTHWEST MEXICO FRIDAY BEGINS TO MOVE NORTHEASTWARD SATURDAY...THE 500MB RIDGE ACROSS THE GULF OF MEXICO WILL WEAKEN ACROSS EAST TX ALLOWING LOW TO MID LEVEL MOISTURE TO INCREASE AND PROVIDE A CHANCE OF SHOWERS AND THUNDERSTORMS FOR SOUTHEAST TX THIS WEEKEND...AS THE 500MB LOW OPENS UP AND EJECTS INTO THE CENTRAL AND SOUTHERN PLAINS AS A TROUGH. WILL GO AHEAD AND INCREASE POPS SLIGHTLY SATURDAY AND SUNDAY BUT REMOVE MENTION OF RAIN CHANCES INTO EARLY NEXT WEEK AS THE SOUTHWESTERLY FLOW ALOFT VEERS TO THE NORTHWEST SUN NIGHT WITH THE TROUGH MOVING ACROSS THE MIDDLE AND LOWER MISSISSIPPI RIVER VALLEY. 32 AVIATION... MVFR CIGS THIS MORNING SHOULD GRADUALLY LIFT INTO THE VFR CATEGORY BY LATE MORNING. PLAN ON BUMPING SE WINDS UP TO AROUND 15KT DURING THE AFTERNOON HOURS FOR MOST TERMINALS. PROBABLY SEE A REPEAT OF MVFR CIGS DEVELOPING OVERNIGHT...BUT WINDS SHOULD AGAIN KEEP THEM FROM GOING TOO LOW. 47 MARINE... MODERATE E & SE FETCH BECOMING WELL ESTABLISHED ACROSS THE ENTIRE GULF WITH HIGH PRESSURE ANCHORED OFF THE EAST COAST AND LOWER PRESSURES SITUATED ACROSS THE PLAINS. THIS SAME SCENARIO SHOULD PERSIST INTO THE WEEKEND. WILL KEEP THE CAUTION FLAGS FLYING IN THE 20-60NM GROUP TODAY (AND WILL LIKELY BE NEEDED MOST OF THE WEEK). MAY SEE SOME PERIODS WHERE FLAGS MAY NEED TO BE EXPANDED INTO THE NEARSHORE GROUP AND/OR ADVSY CRITERIA MAY BE MET OFFSHORE...WHICH TYPICALLY HAPPENS IN THE NIGHTTIME PERIODS THIS TIME OF YEAR WHEN WINDS ARE SLIGHTLY HIGHER. NO FRONTS IN SIGHT FOR THE NEXT 10+ DAYS. 47 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 76 64 78 64 76 / 20 20 10 10 10 HOUSTON (IAH) 77 64 77 64 77 / 20 20 10 10 10 GALVESTON (GLS) 75 65 76 65 73 / 20 20 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH WEDNESDAY MORNING FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. && $$ DISCUSSION...35
AREA FORECAST DISCUSSION...UPDATED FOR AVIATION
NWS FORT WORTH TX
630 AM CDT TUE MAR 20 2007 .AVIATION... MAIN CONCERN IS CIGS DURING THE NEXT FEW HOURS. A WAVE OF INTENSE MOISTURE ADVECTION IS NOW REACHING THE METROPLEX AND IS RESULTING IN MVFR VIS WITH DRIZZLE AND CIGS NEAR 800 FEET. WILL SHOW IFR CIGS IN A TEMPO GROUP THROUGH 14Z...THINKING THAT THEY WILL LIFT BACK TO MVFR FOR THE REMAINDER OF THE MORNING ONCE THE DRIZZLE MOVES ON THROUGH. SOME ELEVATED SHOWERS WILL ALSO BE POSSIBLE AS SHORTWAVE MOVES THROUGH THIS MORNING. WILL LEAVE THUNDER OUT OF TAF AND OPT FOR JUST VCSH. OTHERWISE...THE MVFR CIGS WILL LIFT TO VFR IN SIMILAR FASHION AS SEEN YESTERDAY AROUND MID AFTERNOON BEFORE COMING DOWN TO MVFR AFTER MIDNIGHT TONIGHT. SOUTH WINDS OF 15 TO 20 KNOTS WILL CONTINUE THROUGH THE PERIOD. TR.92 && .DISCUSSION... WATER VAPOR SATELLITE LOOPS SHOW A SHORTWAVE SOUTHWEST OF ABILENE AS OF 08Z...MOVING EAST NORTHEAST ACROSS TEXAS. THE 00Z FWD SOUNDING INDICATED THAT WE HAVE A STRONG CAPPING INVERSION... HOWEVER...THE RUC AND NAM FORECAST SOUNDINGS INDICATE THE CAP IS GOING TO WEAKEN. ACARS DATA INDICATES THAT THIS MAY BE HAPPENING. SO FAR RADAR SHOWS SOME ELEVATED REFLECTIVITY RETURNS ACROSS THE WESTERN ZONES BUT HAVE NOT HAD ANY SURFACE REPORTS OF RAIN. HAVE PLACED 20 PERCENT POPS BACK IN THE FORECAST FOR THE NORTHWESTERN TWO-THIRDS OF THE FORECAST AREAS FOR TODAY. WE WILL START OFF PRETTY WARM THIS MORNING WITH LOWS IN THE LOWER TO MID 60S...ONLY A CATEGORY BELOW THE NORMAL HIGHS. WITH CONSIDERABLE CLOUD COVER...THE DIURNAL TEMPERATURE RANGE WILL ONLY BE 10 TO 15 DEGREES. A LARGE UPPER LEVEL TROUGH WILL MOVE INTO THE WEST COAST DURING THE NEXT 24 HOURS. A LOW WILL THEN CUT OFF OVER CALIFORNIA WEDNESDAY...AND THEN DIG SOUTHWARD INTO BAJA CALIFORNIA BY THURSDAY. THE LOW WILL LIFT NORTHEAST INTO NEW MEXICO BY FRIDAY NIGHT...AND THEN INTO THE CENTRAL PLAINS OVER THE WEEKEND. WE WILL SEE AT LEAST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS WEDNESDAY AND THURSDAY...WITH THE BEST CHANCES ACROSS THE WEST. RAIN CHANCES WILL IMPROVE AREAWIDE FRIDAY THROUGH THE WEEKEND. #58 THE BEST CHANCE OF RAIN DURING THE NEXT FEW DAYS WILL BE TO THE NORTH AND && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 75 63 75 63 76 / 20 10 20 20 20 WACO, TX 76 63 75 63 76 / 20 10 20 20 20 PARIS, TX 73 62 75 61 74 / 20 10 20 20 20 DENTON, TX 75 62 75 63 74 / 20 10 20 20 20 MCKINNEY, TX 73 62 74 62 73 / 20 10 20 20 20 DALLAS, TX 75 64 75 63 76 / 20 10 20 20 20 TERRELL, TX 74 63 75 62 75 / 20 10 20 20 20 CORSICANA, TX 75 62 75 62 75 / 20 10 20 20 20 TEMPLE, TX 75 62 75 63 76 / 10 10 20 20 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 92/58
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
416 AM CDT TUE MAR 20 2007 .DISCUSSION... WATER VAPOR SATELLITE LOOPS SHOW A SHORTWAVE SOUTHWEST OF ABILENE AS OF 08Z...MOVING EAST NORTHEAST ACROSS TEXAS. THE 00Z FWD SOUNDING INDICATED THAT WE HAVE A STRONG CAPPING INVERSION... HOWEVER...THE RUC AND NAM FORECAST SOUNDINGS INDICATE THE CAP IS GOING TO WEAKEN. ACARS DATA INDICATES THAT THIS MAY BE HAPPENING. SO FAR RADAR SHOWS SOME ELEVATED REFLECTIVITY RETURNS ACROSS THE WESTERN ZONES BUT HAVE NOT HAD ANY SURFACE REPORTS OF RAIN. HAVE PLACED 20 PERCENT POPS BACK IN THE FORECAST FOR THE NORTHWESTERN TWO-THIRDS OF THE FORECAST AREAS FOR TODAY. WE WILL START OFF PRETTY WARM THIS MORNING WITH LOWS IN THE LOWER TO MID 60S...ONLY A CATEGORY BELOW THE NORMAL HIGHS. WITH CONSIDERABLE CLOUD COVER...THE DIURNAL TEMPERATURE RANGE WILL ONLY BE 10 TO 15 DEGREES. A LARGE UPPER LEVEL TROUGH WILL MOVE INTO THE WEST COAST DURING THE NEXT 24 HOURS. A LOW WILL THEN CUT OFF OVER CALIFORNIA WEDNESDAY...AND THEN DIG SOUTHWARD INTO BAJA CALIFORNIA BY THURSDAY. THE LOW WILL LIFT NORTHEAST INTO NEW MEXICO BY FRIDAY NIGHT...AND THEN INTO THE CENTRAL PLAINS OVER THE WEEKEND. WE WILL SEE AT LEAST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS WEDNESDAY AND THURSDAY...WITH THE BEST CHANCES ACROSS THE WEST. RAIN CHANCES WILL IMPROVE AREAWIDE FRIDAY THROUGH THE WEEKEND. #58 THE BEST CHANCE OF RAIN DURING THE NEXT FEW DAYS WILL BE TO THE NORTH AND && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 75 63 75 63 76 / 20 10 20 20 20 WACO, TX 76 63 75 63 76 / 20 10 20 20 20 PARIS, TX 73 62 75 61 74 / 20 10 20 20 20 DENTON, TX 75 62 75 63 74 / 20 10 20 20 20 MCKINNEY, TX 73 62 74 62 73 / 20 10 20 20 20 DALLAS, TX 75 64 75 63 76 / 20 10 20 20 20 TERRELL, TX 74 63 75 62 75 / 20 10 20 20 20 CORSICANA, TX 75 62 75 62 75 / 20 10 20 20 20 TEMPLE, TX 75 62 75 63 76 / 10 10 20 20 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 92/58
AREA FORECAST DISCUSSION...UPDATED
NWS GREEN BAY WI
845 PM CDT WED MAR 21 2007 .UPDATE...CLUSTER OF STORMS NR SFC WARM FRONT CONTD ACRS E-C WI. NUMEROUS REPORTS OF PEA-SIZED HAIL RECEIVED DURING THE LATE AFTN AND EARLY EVENING. THE LARGEST HAIL REPORTED WAS 1/2 INCH FM CALUMET COUNTY. STORMS OVER E-C WI WL LIKELY CONT AT BLO SVR INTENSITY AS THEY PUSH E OVER LAKE MICHIGAN. ATTENTION THEN WL FOCUS BACK TO THE W ALONG THE COLD FRONT ACRS WRN WI. THOUGHT THAT MIGHT BE A BETTER WIND THREAT AS MAIN LINE OF CONVECTION WL BE ORIENTED PERPENDICULAR TO LLJ FCST TO INCR TO 50-55 KTS DURING THE EVENING. INCR SFC TEMPS IN THE WARM SECTOR WOULD ALSO MAKE IT EASIER TO GET THE WINDS TO THE GROUND. BUT...THUS FAR THAT SCENARIO HAS NOT BEEN PLAYING OUT. THE LATEST LSR FM MPX INDICATED MAINLY MARGINALLY SVR HAIL WITH THE STORMS. THE LATEST LOCAL MESO ANALYSIS GRAPHICS ALSO INDICATED A DECR IN MUCAPE ACRS THE SRN PART OF THE FCST AREA...THOUGH THAT COULD JUST BE AN ADJUSTMENT TO THE 00Z RAOBS BEING INGESTED. IN ANY CASE...NEED TO WATCH THE STORMS TO THE W FOR A WHILE BEFORE MAKING ANY SIG CHGS TO THE FCST. VSBYS ACRS THE N HAVE EDGED UP FM EARLIER IN THE EVENING...BUT WL CONT DENSE FOG ADVISORY FOR NOW. MIDNIGHT EXPIRATION TIME LOOKS ON TARGET. JS .PREV DISCUSSION...THE COMPLETE DISCUSSION FROM THE PREVIOUS MAIN FORECAST ISSUANCE FOLLOWS. SHORT TERM...MAIN FCST CONCERN WILL BE SCATTERED THUNDERSTORMS LATE THIS AFTERNOON WITH WARM FRONT LIFTING NORTHWARD INTO THE FOX VALLEY... THEN ANOTHER ROUND OF THUNDERSTORMS LATER THIS EVENING AS COLD FRONT APPROACHES FROM MINNESOTA. STEEP MID-LEVEL LAPSE RATES...WARM FRONT LIFTING NORTHEAST ACROSS THE FORECAST AREA AND A SHORT WAVE DISTURBANCE MOVING INTO CENTRAL WISCONSIN ...HAVE COMBINED TO ORGANIZE AN AREA OF SHOWERS AND THUNDERSTORMS CURRENTLY MOVING ACROSS EAST-CENTRAL WISCONSIN AND THE FOX VALLEY. SO FAR...FAR HAVE ONLY RECEIVED A COUPLE REPORTS OF PEA-SIZED HAIL IN PARTS OF THE FOX VALLEY...ALONG WITH SOME BRIEF HEAVY DOWNPOURS. EXPECT THIS ACTIVITY TO CONTINUE TO STEADLIY PROGRESS EASTWARD ACROSS THE AREA. MAIN SHORTWAVE MOVING ACROSS THE DAKOTAS FCST TO MOVE INTO THE STATE LATER THIS EVENING. COLD FRONT OVER CENTRAL MINNESOTA WILL PUSH RAPIDLY EASTWARD ACROSS THE STATE OVERNIGHT AND SHOULD BE EAST OF THE STATE BY 12Z THURSDAY. MID-LEVEL LAPSE RATES ALONG AND AHEAD OF THE FRONT STILL FCST TO BE QUITE STEEP AND 850 LLJ FCST TO INTENSIFY TO 50-60 KNOTS AFTER SUNSET AS WELL. AS PER LATEST SPC DAY1 OUTLOOK...POTENTIAL FOR SOME SCATTERED MARGINALLY SEVERE THUNDERSTORMS AS THE FRONT APPROACHES LATER THIS EVENING. LOOKS LIKE BEST SHOT FOR THUNDERSTORMS WILL BE BETWEEN ABOUT 02Z AND 05Z. MAIN THREAT WILL BE MARGINALLY SEVERE HAIL AND DAMAGING WINDS. AIRCRAFT SOUNDINGS OVER CENTRAL WI THIS AFTERNOON SHOWING 50 KNOTS JUST A FEW KFT OFF THE SURFACE SO CERTAINLY SOME POTENTIAL FOR DAMAGING WIND GUSTS IF CAN REMOVE LOW-LEVEL STABLE LAYER THIS EVENING. STRONG SUBSIDENCE IN THE WAKE OF THE FRONT ON THURSDAY SHOULD BRING CLEARING SKIES...BUT EXPECT SOME GUSTY NORTHWEST WINDS DURING THE AFTERNOON. LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY. NCEP ONCE AGAIN FAVORS THE ECMWF FOR THIS PERIOD...SO IT WAS FOLLOWED WHEN POSSIBLE. UPPER FLOW STARTS OUT ZONAL ACROSS THE NORTHERN CONUS AND SOUTHERN CANADA AS A CUT-OFF LOW HANGS AROUND THE BAJA CALIFORNIA/DESERT SOUTHWEST REGION. A RIDGE IS FORECAST TO AMPLIFY ACROSS THE WESTERN GREAT LAKES REGION OVER THE WEEKEND AS THE CLOSED CIRCULATION BECOMES AN OPEN WAVE. THE SHORT WAVE LATER PASSES THROUGH THE REGION DURING THE EARLY PART OF NEXT WEEK. TEMPERATURES SHOULD START OUT QUITE A BIT ABOVE NORMAL IN THE ZONAL FLOW. AFTER A COLD FRONT MOVES ACROSS THE REGION TEMPERATURES COOL OFF A BIT BUT REMAIN ABOVE NORMAL. AS FOR PCPN...THURSDAY NIGHT AND FRIDAY SHOULD BE DRY WITH WISCONSIN UNDER THE INFLUENCE OF WEAK SURFACE AND UPPER RIDGES. SHORT WAVE ENERGY AND INCREASED MOISTURE BRING A CHANCE OF PCPN...MAINLY TO THE NORTHERN PART OF THE FORECAST AREA FRIDAY NIGHT...SNOW SHOWERS CANNOT BE RULED OUT IN THE NORTH SO THEY WERE ALSO MENTIONED. SURFACE AND UPPER LEVEL RIDGES DOMINATE FOR SATURDAY AND SATURDAY NIGHT...KEEPING THE WEATHER DRY. THE APPROACHING SHORT WAVE IN SOUTHWEST FLOW AND A COLD FRONT MOVING EAST ACROSS THE PLAINS BRING PCPN CHANCES SUNDAY THROUGH EARLY MONDAY NIGHT. SURFACE HIGH PRESSURE BUILDING INTO THE REGION SHOULD BRING DRY CONDITIONS BACK FOR TUESDAY AND WEDNESDAY. && .GRB WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL MIDNIGHT WIZ005-010>013-018>022-030-031-073-074- && $$ WEATHER.GOV/GREENBAY
AREA FORECAST DISCUSSION...UPDATED
NWS GREEN BAY WI
545 PM CDT WED MAR 21 2007 .UPDATE...COORD W SPC AND DECIDED TO FOREGO A WATCH FOR AT LEAST THE NEXT COUPLE HRS. MAY NEED TO ISSUE A FEW WARNINGS...BUT DON/T THINK ACTIVITY WL GET STG AND WIDESPREAD ENOUGH IN THE IMMEDIATE FUTURE. THINGS COULD CHANGE QUICKLY AN HR OR TWO AFTER DARK WHEN THE LLJ CRANKS UP. HIGH DWPTS STREAMING NWD OVER THE REMAINING SNOW COVER WL GENERATE DENSE FG TNGT. WL POST A DENSE FG ADVISORY FOR AREAS N OF HIGHW AY 29. UPDATED PRODUCT SUITE WL BE OUT ASAP. JS .PREV DISCUSSION...THE COMPLETE DISCUSSION FROM THE PREVIOUS MAIN FORECAST ISSUANCE FOLLOWS. SHORT TERM...MAIN FCST CONCERN WILL BE SCATTERED THUNDERSTORMS LATE THIS AFTERNOON WITH WARM FRONT LIFTING NORTHWARD INTO THE FOX VALLEY... THEN ANOTHER ROUND OF THUNDERSTORMS LATER THIS EVENING AS COLD FRONT APPROACHES FROM MINNESOTA. STEEP MID-LEVEL LAPSE RATES...WARM FRONT LIFTING NORTHEAST ACROSS THE FORECAST AREA AND A SHORT WAVE DISTURBANCE MOVING INTO CENTRAL WISCONSIN ...HAVE COMBINED TO ORGANIZE AN AREA OF SHOWERS AND THUNDERSTORMS CURRENTLY MOVING ACROSS EAST-CENTRAL WISCONSIN AND THE FOX VALLEY. SO FAR...FAR HAVE ONLY RECEIVED A COUPLE REPORTS OF PEA-SIZED HAIL IN PARTS OF THE FOX VALLEY...ALONG WITH SOME BRIEF HEAVY DOWNPOURS. EXPECT THIS ACTIVITY TO CONTINUE TO STEADLIY PROGRESS EASTWARD ACROSS THE AREA. MAIN SHORTWAVE MOVING ACROSS THE DAKOTAS FCST TO MOVE INTO THE STATE LATER THIS EVENING. COLD FRONT OVER CENTRAL MINNESOTA WILL PUSH RAPIDLY EASTWARD ACROSS THE STATE OVERNIGHT AND SHOULD BE EAST OF THE STATE BY 12Z THURSDAY. MID-LEVEL LAPSE RATES ALONG AND AHEAD OF THE FRONT STILL FCST TO BE QUITE STEEP AND 850 LLJ FCST TO INTENSIFY TO 50-60 KNOTS AFTER SUNSET AS WELL. AS PER LATEST SPC DAY1 OUTLOOK...POTENTIAL FOR SOME SCATTERED MARGINALLY SEVERE THUNDERSTORMS AS THE FRONT APPROACHES LATER THIS EVENING. LOOKS LIKE BEST SHOT FOR THUNDERSTORMS WILL BE BETWEEN ABOUT 02Z AND 05Z. MAIN THREAT WILL BE MARGINALLY SEVERE HAIL AND DAMAGING WINDS. AIRCRAFT SOUNDINGS OVER CENTRAL WI THIS AFTERNOON SHOWING 50 KNOTS JUST A FEW KFT OFF THE SURFACE SO CERTAINLY SOME POTENTIAL FOR DAMAGING WIND GUSTS IF CAN REMOVE LOW-LEVEL STABLE LAYER THIS EVENING. STRONG SUBSIDENCE IN THE WAKE OF THE FRONT ON THURSDAY SHOULD BRING CLEARING SKIES...BUT EXPECT SOME GUSTY NORTHWEST WINDS DURING THE AFTERNOON. LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY. NCEP ONCE AGAIN FAVORS THE ECMWF FOR THIS PERIOD...SO IT WAS FOLLOWED WHEN POSSIBLE. UPPER FLOW STARTS OUT ZONAL ACROSS THE NORTHERN CONUS AND SOUTHERN CANADA AS A CUT-OFF LOW HANGS AROUND THE BAJA CALIFORNIA/DESERT SOUTHWEST REGION. A RIDGE IS FORECAST TO AMPLIFY ACROSS THE WESTERN GREAT LAKES REGION OVER THE WEEKEND AS THE CLOSED CIRCULATION BECOMES AN OPEN WAVE. THE SHORT WAVE LATER PASSES THROUGH THE REGION DURING THE EARLY PART OF NEXT WEEK. TEMPERATURES SHOULD START OUT QUITE A BIT ABOVE NORMAL IN THE ZONAL FLOW. AFTER A COLD FRONT MOVES ACROSS THE REGION TEMPERATURES COOL OFF A BIT BUT REMAIN ABOVE NORMAL. AS FOR PCPN...THURSDAY NIGHT AND FRIDAY SHOULD BE DRY WITH WISCONSIN UNDER THE INFLUENCE OF WEAK SURFACE AND UPPER RIDGES. SHORT WAVE ENERGY AND INCREASED MOISTURE BRING A CHANCE OF PCPN...MAINLY TO THE NORTHERN PART OF THE FORECAST AREA FRIDAY NIGHT...SNOW SHOWERS CANNOT BE RULED OUT IN THE NORTH SO THEY WERE ALSO MENTIONED. SURFACE AND UPPER LEVEL RIDGES DOMINATE FOR SATURDAY AND SATURDAY NIGHT...KEEPING THE WEATHER DRY. THE APPROACHING SHORT WAVE IN SOUTHWEST FLOW AND A COLD FRONT MOVING EAST ACROSS THE PLAINS BRING PCPN CHANCES SUNDAY THROUGH EARLY MONDAY NIGHT. SURFACE HIGH PRESSURE BUILDING INTO THE REGION SHOULD BRING DRY CONDITIONS BACK FOR TUESDAY AND WEDNESDAY. && .GRB WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL MIDNIGHT WIZ005-010>013-018>022-030-031-073-074- && $$ WEATHER.GOV/GREENBAY
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
415 PM CDT WED MAR 21 2007 .SHORT TERM...MAIN FCST CONCERN WILL BE SCATTERED THUNDERSTORMS LATE THIS AFTERNOON WITH WARM FRONT LIFTING NORTHWARD INTO THE FOX VALLEY... THEN ANOTHER ROUND OF THUNDERSTORMS LATER THIS EVENING AS COLD FRONT APPROACHES FROM MINNESOTA. STEEP MID-LEVEL LAPSE RATES...WARM FRONT LIFTING NORTHEAST ACROSS THE FORECAST AREA AND A SHORT WAVE DISTURBANCE MOVING INTO CENTRAL WISCONSIN ...HAVE COMBINED TO ORGANIZE AN AREA OF SHOWERS AND THUNDERSTORMS CURRENTLY MOVING ACROSS EAST-CENTRAL WISCONSIN AND THE FOX VALLEY. SO FAR...FAR HAVE ONLY RECEIVED A COUPLE REPORTS OF PEA-SIZED HAIL IN PARTS OF THE FOX VALLEY...ALONG WITH SOME BRIEF HEAVY DOWNPOURS. EXPECT THIS ACTIVITY TO CONTINUE TO STEADLIY PROGRESS EASTWARD ACROSS THE AREA. MAIN SHORTWAVE MOVING ACROSS THE DAKOTAS FCST TO MOVE INTO THE STATE LATER THIS EVENING. COLD FRONT OVER CENTRAL MINNESOTA WILL PUSH RAPIDLY EASTWARD ACROSS THE STATE OVERNIGHT AND SHOULD BE EAST OF THE STATE BY 12Z THURSDAY. MID-LEVEL LAPSE RATES ALONG AND AHEAD OF THE FRONT STILL FCST TO BE QUITE STEEP AND 850 LLJ FCST TO INTENSIFY TO 50-60 KNOTS AFTER SUNSET AS WELL. AS PER LATEST SPC DAY1 OUTLOOK...POTENTIAL FOR SOME SCATTERED MARGINALLY SEVERE THUNDERSTORMS AS THE FRONT APPROACHES LATER THIS EVENING. LOOKS LIKE BEST SHOT FOR THUNDERSTORMS WILL BE BETWEEN ABOUT 02Z AND 05Z. MAIN THREAT WILL BE MARGINALLY SEVERE HAIL AND DAMAGING WINDS. AIRCRAFT SOUNDINGS OVER CENTRAL WI THIS AFTERNOON SHOWING 50 KNOTS JUST A FEW KFT OFF THE SURFACE SO CERTAINLY SOME POTENTIAL FOR DAMAGING WIND GUSTS IF CAN REMOVE LOW-LEVEL STABLE LAYER THIS EVENING. STRONG SUBSIDENCE IN THE WAKE OF THE FRONT ON THURSDAY SHOULD BRING CLEARING SKIES...BUT EXPECT SOME GUSTY NORTHWEST WINDS DURING THE AFTERNOON. .LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY. NCEP ONCE AGAIN FAVORS THE ECMWF FOR THIS PERIOD...SO IT WAS FOLLOWED WHEN POSSIBLE. UPPER FLOW STARTS OUT ZONAL ACROSS THE NORTHERN CONUS AND SOUTHERN CANADA AS A CUT-OFF LOW HANGS AROUND THE BAJA CALIFORNIA/DESERT SOUTHWEST REGION. A RIDGE IS FORECAST TO AMPLIFY ACROSS THE WESTERN GREAT LAKES REGION OVER THE WEEKEND AS THE CLOSED CIRCULATION BECOMES AN OPEN WAVE. THE SHORT WAVE LATER PASSES THROUGH THE REGION DURING THE EARLY PART OF NEXT WEEK. TEMPERATURES SHOULD START OUT QUITE A BIT ABOVE NORMAL IN THE ZONAL FLOW. AFTER A COLD FRONT MOVES ACROSS THE REGION TEMPERATURES COOL OFF A BIT BUT REMAIN ABOVE NORMAL. AS FOR PCPN...THURSDAY NIGHT AND FRIDAY SHOULD BE DRY WITH WISCONSIN UNDER THE INFLUENCE OF WEAK SURFACE AND UPPER RIDGES. SHORT WAVE ENERGY AND INCREASED MOISTURE BRING A CHANCE OF PCPN...MAINLY TO THE NORTHERN PART OF THE FORECAST AREA FRIDAY NIGHT...SNOW SHOWERS CANNOT BE RULED OUT IN THE NORTH SO THEY WERE ALSO MENTIONED. SURFACE AND UPPER LEVEL RIDGES DOMINATE FOR SATURDAY AND SATURDAY NIGHT...KEEPING THE WEATHER DRY. THE APPROACHING SHORT WAVE IN SOUTHWEST FLOW AND A COLD FRONT MOVING EAST ACROSS THE PLAINS BRING PCPN CHANCES SUNDAY THROUGH EARLY MONDAY NIGHT. SURFACE HIGH PRESSURE BUILDING INTO THE REGION SHOULD BRING DRY CONDITIONS BACK FOR TUESDAY AND WEDNESDAY. && .AVIATION...VFR CONDITIONS ARE EXPECTED THRU MOST OF TNGT WITH A GRADUAL LOWERING OF AN AC DECK AND SC ARRIVING LATE TNGT. LLWS CONDITIONS WL EXIST TNGT AS STRENGTHENING LOW LVL JET OCCURS. MVFR CONDITIONS ARE THEN FCST FOR LATE TNGT AND WED WITH SCT IFR CONDITIONS UNDER SHWRS AND FOG. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ EB/MG WEATHER.GOV/GREENBAY
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 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...UPDATED
NWS GREEN BAY WI
1130 PM CDT WED MAR 21 2007 .UPDATE...PLAN TO LET DENSE FOG ADVISORY EXPIRE AT MIDNIGHT AS SCHEDULED. THE COLD FRONT NOW WORKING EWD ACRS THE FCST AREA. THERE WL STILL BE SOME PATCHY DENSE FG IN THE NE...BUT NOT ENOUGH TO EXTEND THE ADVISORY. SOME SFC WIND GUSTS NOW STARTING TO SHOW UP WITH STORMS TO THE S....BUT THE CONVECTION ACRS THE FCST AREA REMAINED RATHER WK AND DISORGANIZED. TREND OF PREV FCST OF CHANGING OVER TO JUST SCT SHOWERS AND THEN ENDING PCPN FM NW-SE DURING THE REST OF THE NIGHT LOOKS GOOD. TEMPS HAVE JUST ABOUT FINISHED RISING...SO WL REVERT BACK TO COVENTIONAL LOW TEMP WORDING IN THE ZFP. JS .PREV DISCUSSION...THE COMPLETE DISCUSSION FROM THE PREVIOUS MAIN FORECAST ISSUANCE FOLLOWS. SHORT TERM...MAIN FCST CONCERN WILL BE SCATTERED THUNDERSTORMS LATE THIS AFTERNOON WITH WARM FRONT LIFTING NORTHWARD INTO THE FOX VALLEY... THEN ANOTHER ROUND OF THUNDERSTORMS LATER THIS EVENING AS COLD FRONT APPROACHES FROM MINNESOTA. STEEP MID-LEVEL LAPSE RATES...WARM FRONT LIFTING NORTHEAST ACROSS THE FORECAST AREA AND A SHORT WAVE DISTURBANCE MOVING INTO CENTRAL WISCONSIN ...HAVE COMBINED TO ORGANIZE AN AREA OF SHOWERS AND THUNDERSTORMS CURRENTLY MOVING ACROSS EAST-CENTRAL WISCONSIN AND THE FOX VALLEY. SO FAR...FAR HAVE ONLY RECEIVED A COUPLE REPORTS OF PEA-SIZED HAIL IN PARTS OF THE FOX VALLEY...ALONG WITH SOME BRIEF HEAVY DOWNPOURS. EXPECT THIS ACTIVITY TO CONTINUE TO STEADLIY PROGRESS EASTWARD ACROSS THE AREA. MAIN SHORTWAVE MOVING ACROSS THE DAKOTAS FCST TO MOVE INTO THE STATE LATER THIS EVENING. COLD FRONT OVER CENTRAL MINNESOTA WILL PUSH RAPIDLY EASTWARD ACROSS THE STATE OVERNIGHT AND SHOULD BE EAST OF THE STATE BY 12Z THURSDAY. MID-LEVEL LAPSE RATES ALONG AND AHEAD OF THE FRONT STILL FCST TO BE QUITE STEEP AND 850 LLJ FCST TO INTENSIFY TO 50-60 KNOTS AFTER SUNSET AS WELL. AS PER LATEST SPC DAY1 OUTLOOK...POTENTIAL FOR SOME SCATTERED MARGINALLY SEVERE THUNDERSTORMS AS THE FRONT APPROACHES LATER THIS EVENING. LOOKS LIKE BEST SHOT FOR THUNDERSTORMS WILL BE BETWEEN ABOUT 02Z AND 05Z. MAIN THREAT WILL BE MARGINALLY SEVERE HAIL AND DAMAGING WINDS. AIRCRAFT SOUNDINGS OVER CENTRAL WI THIS AFTERNOON SHOWING 50 KNOTS JUST A FEW KFT OFF THE SURFACE SO CERTAINLY SOME POTENTIAL FOR DAMAGING WIND GUSTS IF CAN REMOVE LOW-LEVEL STABLE LAYER THIS EVENING. STRONG SUBSIDENCE IN THE WAKE OF THE FRONT ON THURSDAY SHOULD BRING CLEARING SKIES...BUT EXPECT SOME GUSTY NORTHWEST WINDS DURING THE AFTERNOON. LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY. NCEP ONCE AGAIN FAVORS THE ECMWF FOR THIS PERIOD...SO IT WAS FOLLOWED WHEN POSSIBLE. UPPER FLOW STARTS OUT ZONAL ACROSS THE NORTHERN CONUS AND SOUTHERN CANADA AS A CUT-OFF LOW HANGS AROUND THE BAJA CALIFORNIA/DESERT SOUTHWEST REGION. A RIDGE IS FORECAST TO AMPLIFY ACROSS THE WESTERN GREAT LAKES REGION OVER THE WEEKEND AS THE CLOSED CIRCULATION BECOMES AN OPEN WAVE. THE SHORT WAVE LATER PASSES THROUGH THE REGION DURING THE EARLY PART OF NEXT WEEK. TEMPERATURES SHOULD START OUT QUITE A BIT ABOVE NORMAL IN THE ZONAL FLOW. AFTER A COLD FRONT MOVES ACROSS THE REGION TEMPERATURES COOL OFF A BIT BUT REMAIN ABOVE NORMAL. AS FOR PCPN...THURSDAY NIGHT AND FRIDAY SHOULD BE DRY WITH WISCONSIN UNDER THE INFLUENCE OF WEAK SURFACE AND UPPER RIDGES. SHORT WAVE ENERGY AND INCREASED MOISTURE BRING A CHANCE OF PCPN...MAINLY TO THE NORTHERN PART OF THE FORECAST AREA FRIDAY NIGHT...SNOW SHOWERS CANNOT BE RULED OUT IN THE NORTH SO THEY WERE ALSO MENTIONED. SURFACE AND UPPER LEVEL RIDGES DOMINATE FOR SATURDAY AND SATURDAY NIGHT...KEEPING THE WEATHER DRY. THE APPROACHING SHORT WAVE IN SOUTHWEST FLOW AND A COLD FRONT MOVING EAST ACROSS THE PLAINS BRING PCPN CHANCES SUNDAY THROUGH EARLY MONDAY NIGHT. SURFACE HIGH PRESSURE BUILDING INTO THE REGION SHOULD BRING DRY CONDITIONS BACK FOR TUESDAY AND WEDNESDAY. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ WEATHER.GOV/GREENBAY
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 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 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