Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 03/14/07

AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
830 AM PDT MON MAR 12 2007 .SYNOPSIS... HIGH PRESSURE ALOFT AND WEAK OFFSHORE FLOW WILL BRING VERY DRY WEATHER TODAY WITH NEAR RECORD HIGH TEMPERATURES FOR INLAND AREAS. HIGH PRESSURE WILL WEAKEN SLIGHTLY AND WEAK ONSHORE FLOW WILL RETURN AT TIMES FOR TUESDAY THROUGH SATURDAY BRINGING MINOR COOLING AND SOME RETURN OF NIGHT AND MORNING LOW CLOUDS AND FOG TO AREAS NEAR THE COAST. FOR LATER NEXT WEEKEND THROUGH EARLY NEXT WEEK...ONSHORE FLOW MAY STRENGTHEN...BRINGING GREATER COOLING AND RETURN OF THE MARINE LAYER. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (TODAY THROUGH WEDNESDAY)... OFFSHORE FLOW CONTINUES WITH ABOUT 9 MBS BETWEEN KTPH AND KSAN WHILE THE GRADIENT BETWEEN THE COAST AND THE SOUTHERN DESERTS HAS GONE WEAK ONSHORE BY ABOUT 1 MB. MORNING ACARS DATA INDICATES A WARM AIR MASS REMAINS OVER THE AREA. ONE INBOUND ON SHORT FINAL TO KSAN INDICATED A TEMPERATURE OF 22C AT 400 FEET WHILE SURFACE TEMPERATURE AT KSAN AT THE TIME WAS AROUND 15C. 12Z NAM CONTINUES TO SHOW THE RIDGE DOMINATING THROUGH WEDNESDAY ALTHOUGH BEGINNING TO WEAKEN ON WEDNESDAY AND CONTINUES TO FLATTEN INTO THURSDAY. TODAY APPEARS TO BE THE PEAK FOR THE HEATING WITH COASTAL AREAS BEGINNING TO COOL DOWN ON TUESDAY. THE NAM INDICATES A WEAK EDDY DEVELOPING TUESDAY AFTERNOON INTO WEDNESDAY WHICH WILL HELP WITH THE COOL DOWN ALONG THE COAST AND HELP THE MARINE LAYER TO RECOVER. && .LONG TERM (THURSDAY THROUGH SUNDAY)... MINOR DAY TO DAY CHANGES FOR THURSDAY THROUGH SATURDAY WITH SOME OVERNIGHT COASTAL LOW CLOUDS AT TIMES EXTENDING LOCALLY INLAND AND WITH TEMPERATURES FOR INLAND AREAS REMAINING WELL ABOVE SEASONAL AVERAGES...BUT MOSTLY NOT RECORD SETTING. WEAKENING HIGH PRESSURE ALOFT AND A LITTLE STRONGER ONSHORE FLOW MAY BRING ADDITIONAL COOLING FOR SUNDAY THROUGH EARLY NEXT WEEK WITH A GREATER RETURN OF THE MARINE LAYER. && .AVIATION... 121600Z...VFR CONDITIONS WILL CONTINUE TODAY. LOCAL 5 MILE VSBYS ARE POSSIBLE OVER NORTHERN ORANGE COUNTY DUE TO SMOKE FROM WILDFIRES. WINDS HAVE DECREASED AND ARE NOT EXPECTED TO BE AN ISSUE TODAY. FOG IS AT THE COAST NOT TOO FAR SOUTH OF THE BORDER...SO LOCAL DENSE FOG COULD APPEAR AT THE COAST NEAR KSAN LATE TONIGHT OR TUE MORNING WITH THE INCREASE IN ONSHORE FLOW. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...RED FLAG WARNING UNTIL 7 PM PDT THIS EVENING FOR ORANGE COUNTY COASTAL AREAS-RIVERSIDE COUNTY MOUNTAINS-INCLUDING THE SAN JACINTO RANGER DISTRICT OF THE SAN BERNARDINO NATIONAL FOREST-SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SAN BERNARDINO COUNTY MOUNTAINS-INCLUDING THE MOUNTAIN TOP AND FRONT COUNTRY RANGER DISTRICTS OF THE SAN BERNARDINO NATIONAL FOREST-SAN DIEGO COUNTY INLAND VALLEYS- SAN DIEGO COUNTY MOUNTAINS-INCLUDING THE PALOMAR AND DESCANSO RANGER DISTRICTS OF THE CLEVELAND NATIONAL FOREST- SANTA ANA MOUNTAINS-INCLUDING THE TRABUCO RANGER DISTRICT OF THE CLEVELAND NATIONAL FOREST. PZ...NONE. && $$ PUBLIC...HORTON AVIATION/MARINE...MM NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
355 PM CDT TUE MAR 13 2007 .DISCUSSION... 355 PM CDT NOW THAT SPRING FEVER HAS BROKEN OUT IT WILL BECOME APPARENT TOMORROW WHY IT IS A TRANSITION SEASON. MODERATELY STRONG SW WINDS HAVE BUMPED TEMPS INTO THE LOWER AND MID 70S AND DWPTS INTO THE LOWER AND MID 50S. A COLD FRONT EXTENDS FROM LOW PRES IN EASTERN ONTARIO SWWARD ACROSS NW WI...SE MN AND NW IA TO DVLPG LO PRES IN ERN NEB. THE PLAINS LO IS DVLPG IN RESPONSE TO A WK SHORT WAVE MOVING E FROM THE NRN ROCKIES INTO THE DAKOTAS AND WILL SLOW THE SEWRD PROGRESS OF THIS PORTION OF THE FRONTAL BOUNDARY WHILE THE NRN PORTION THRU THE UPPER GRTLKS. MODELS HAVE FRONT INTO SERN WI AND FAR NW IL AT 06Z...SINKING INTO FAR NE IL BY 12Z. EVEN THO THE WK CIRCULATION ON THE BNDRY IS FCST TO MOVE ACROSS NRN IL LATE TONIGHT AND EARLY WED MORNING IT WOULD APPEAR THAT THE GFS IDEA OF HAVING THE FRONT WORK ITS WAY DOWN THE LENGTH OF LK MI DEEPER INTO NERN IL IS REASONABLE GIVEN COLD LK WATER AND THIS TYPICALLY SEEN IN THE SPRING. SHALLOW LAKE ENHANCED COLD AIR UNDERCUTTING MILD MOIST AIR EXPECTED TO GENERATE LO CLOUDS...FOG AND DRIZZLE OVERNIGHT. MID LEVEL MAVE MOVES BY WED MORNING WITH BOUNDARY RESPONDING BY MOVING FURTHER S INTO THE SRN PORTION OF THE FA...AND INTO CENTRAL IL BY 00Z THU. WITH MOIST MILD AIRMASS S OF FRONT AND SOME INDICATION OF MID LEVEL COOLING K AND SHOWALTER INDICES SHOW POTENTIAL FOR THUNDER ALONG AND JUST BEHIND FRONT WED AFTERNOON. COOLER AIR REMAINS IN PLACE ACROSS THE UPPER MIDWEST AND GRTLKS INTO THE WEEKEND AS UPPER CIRCULATION CURRENTLY ON THE BC COAST DROPS SE INTO THE UPPER MIDWEST LATE THU AND CARVES OUT A DEEPENING TROF OVER THE GRTLKS FRI. MINOR IMPULSE AHEAD OF THE UPR LO WILL MOV INTO THE REGION ON THU BRINGING A CHC OF SOME LIGHT RAIN WHILE LO LEVEL CIRCULATION ASSOCIATED WITH THE MAIN UPPER IMPULSE TRACKS FROM MN INTO NRN WI. THIS SHUD KEEP THE THREAT OF PRECIP TO THE N OF THE FA. TRS && .AVIATION DISCUSSION REGARDING 18Z TAFS... 1252 PM CDT MAIN AVIATION FCST FOCUS IS WITH EVENTUAL APPROACH OF COLD FRONT WEDNESDAY MORNING...AND POTENTIAL FOR IFR/LIFR CONDITIONS AS WIND SHIFTS NE OFF COOL LAKE MICHIGAN INTO MOIST LLVL AIR ALONG/SOUTH OF FRONT. BREEZY SWLY LLVL FLOW THIS AFTN AHEAD OF SFC TROF/COLD FRONT NOW FROM CENTRAL ONT TO KSUX VCNTY. 12Z RAOBS AND RECENT ACARS SNDGS INDICATE 30-40 KT WINDS JUST ABOVE SFC...WHICH SFC OBS SHOW IS NOW BEGINNING TO MIX DOWN TO GROUND LVL. WRF BUFKIT MOMENTUM TRANSFER INDICATES 25 KTS A GOOD APPROXIMATE GUST MAGNITUDE...PERHAPS A LITTLE HIGHER IF FAIRLY DENSE CIRRUS SHIELD THINS OUT. GRADIENT WEAKENS A BIT TNGT AS SFC TROF SETTLES ACROSS WI/IA...WHICH ALONG WITH DIURNAL TEMP DECREASE SHOULD RESULT IN LOSS OF STRONGER GUSTS AROUND SUNSET. MODELS APPEAR TO BE FLIP/FLOPPING SLIGHTLY WITH TIMING OF COLD FRONT SAGGING INTO NORTHERN IL. 12Z RUNS OF WRF/GFS BRING FRONT INTO NRN IL JUST BEFORE 12Z...WITH THERMAL GRADIENT ALONG COLD LAKE MICHIGAN EXPECTED TO ALLOW FRONT TO SLIDE FAIRLY QUICKLY SOUTH OF THE LAKE DURG THE MORNING. ULTIMATE FROPA WILL DEPEND ON SMALL SCALE INTERACTION OF BOUNDARY/TEMP GRADIENT ALONG LAKE THOUGH THIS TIMING APPEARS REASONABLE FOR NOW...AND WILL INDICATE WIND SHIFT IN 12-13Z PERIOD ACROSS TERMINALS. WITH WIND TURNING NORTHEAST...POTENTIAL FOR IFR/LIFR CONDITIONS TO DVLP AT LEAST INITIALLY BEHIND FROPA...AS COLD LLVL AIR OFF LAKE IMPINGES ON 50+ DEG SFC DEWPOINTS IN WRM/MOIST LLVL CONDITIONS ALONG/S OF FRONT. FULL RESOLUTION BUFFER FCST SNDGS FROM WRF INDICATE CIGS DVLPG IN 300-500 FT RANGE...AND VARIOUS MOS GUIDANCE ALSO HINTING AT LOW CIG/VIS CONDITIONS. SOME DZ LIKELY AS WELL IN WEAKLY CONVERGENT SATURATED BOUNDARY LAYER. HAVE TRIED TO INDICATE SOME IMPROVEMENT TO HIGHER IFR BY LATER MORNING. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1252 PM CDT TUE MAR 13 2007 .DISCUSSION... ...NEAR RECORD WARMTH TODAY AND CHANCE OF THUNDERSTORMS WED... FOCUS THIS MORNING IS THE FIRST 48HRS WITH THE REMAINDER OF THE FORECAST UNCHANGED. FOG HAS BECOME WIDESPREAD ACROSS SOUTHERN WI AND NE IA...WHERE A HEALTHY SNOW PACK SLOWLY MELTS. VIS MAY DROP INTO 3-5SM RANGE ACROSS THE NORTHWEST THRU DAWN BUT WILL QUICKLY BURN OFF AFTER SUNRISE. GUIDANCE SUGGESTS FOG MAY BECOME A LARGER PROBLEM TONIGHT INTO WEDNESDAY MORNING. SW FLOW DOES DIMINISH AGAIN AND LOW LEVEL MOISTURE CONTINUES TO INCREASE. CONFIDENCE NOT HIGH WITH REGARDS TO HOW LOW VIS MAY DROP...BUT MENTION OF PATCHY FOG REASONABLE AT THIS POINT. HIGHS MONDAY CLIMBED INTO THE LOW/MID 60S WITH A GOOD 25 DEGREE RISE ABOVE MONDAY MORNING LOWS. WITH TEMPS STARTING IN THE MID TO UPPER 40S THIS MORNING...850MB TEMPS THAT CONTINUE TO WARM THRU THE DAY AND ONLY CIRRUS...WHICH WILL LIKELY THIN SOME DURING THE DAY... EXPECT ANOTHER 25...PERHAPS 30 DEGREE RISE FROM MORNING LOWS PUSHING HIGHS INTO THE LOW/MID 70S TODAY. SEE CLIMATE SECTION BELOW FOR MORE DETAILS. FRONTAL LOCATION/TIMING BECOMING CLEARER THIS MORNING BUT PRECIP TIMING/CHANCES REMAIN A CHALLENGE. DRY TODAY BUT A WEAK SHORTWAVE LIFTS NE ACROSS THE OH VALLEY LATE TONIGHT INTO WED MORNING. ALL THE MODELS SHOW SOME REFLECTION OF THIS FEATURE THOUGH THE NAM IS THE WEAKEST AND IS FURTHER SOUTH. EXPECT THIS TO BE THE ONLY PRECIP MAKER TO AFFECT THE CWA THRU SUNRISE WED AS THE FRONT REMAINS NORTH OF THE CWA AND HAVE ADDED A CHANCE OF SHOWERS FOR THE SE THIRD OR SO OF THE CWA...MAINLY AFTER MIDNIGHT. GOING SPRINKLES ACROSS THE REST OF THE AREA POSSIBLE BUT DIFFICULT TO FIND MUCH OF A FOCUS AND HAVE REMOVED. WEDNESDAY APPEARS TO BE THE MOST DIFFICULT PERIOD FOR PRECIP. THE FRONT WILL BE ALONG THE WI/IL BORDER AT DAY BREAK...AND MAY SLIDE SOUTH ALONG THE LAKESHORE DURING THE MORNING. THUS...TEMP FORECAST ACROSS THE NORTH AND THE LAKESHORE/DOWNTOWN WED WILL BE DIFFICULT AT BEST. HAVE BUMPED HIGHS TO THE UPPER 50S/LOWER 60S NORTH WITH THE IDEA THAT HIGHS WILL OCCUR IN THE MORNING AHEAD OF THE FRONT. WHAT HAPPENS AFTER THAT IS HARD TO SAY...MAY SEE STEADY OR SLOWLY FALLING TEMPS INLAND...THOUGH IF WINDS TURN NE...THE LAKESHORE MAY DROP BACK INTO THE 40S. SOUTHERN CWA SHOULD SEE TEMPS WARM BACK INTO THE LOWER 70S. WOULD PREFER TO KEEP WED MORNING DRY BUT MAY NEED TO KEEP LOW CHANCE POPS NEAR THE FRONT. BY WED AFTERNOON/EVENING...CHANCE FOR SOME THUNDERSTORMS WITH DAYTIME HEATING AND A SLOW SAGGING SOUTHWARD FRONT. SPC NOW HAS MUCH OF THE AREA IN SLGT RISK FOR THIS PERIOD. DEWPOINTS DURING THIS TIME BARELY REACH LOWER 50S...AND SOUNDINGS RATHER DRY...AND SOUTH OF THE FRONT FAIRLY UNIDIRECTIONAL SUGGESTING WIND MIGHT BE THE GREATEST THREAT OF THE STRONGEST STORMS. SEE SWODY2 FOR MORE DETAILS. FRONT SLIDES SOUTH WEDNESDAY EVENING...WITH ANY TS LIKELY ENDING BY MID EVENING...AND CLEARS CWA EARLY THURSDAY MORNING. MUCH COLDER THURSDAY INTO FRIDAY...BUT AGAIN NO CHANGES HERE ATTM. CMS && .CLIMATE... HIGHS IN THE LOW/MID 70S TODAY WILL APPROACH RECORDS AND WILL CONTINUE NEAR RECORD HIGH WORDING IN ZFP. AT ORD...FORECAST HIGH TODAY IS 73. RECORD FOR TODAY...MARCH 13... IS 72 SET IN 1990 AND TIED IN 1995. THE LAST TIME ORD REACHED 70 DEGREES WAS ON OCTOBER 30 2006 WHEN THE HIGH WAS 70. AT RFD...FORECAST HIGH TODAY IS 70. RECORD FOR TODAY...MARCH 13... IS 70 SET IN 1995. THE LAST TIME RFD REACHED 70 DEGREES OR HIGHER WAS ON OCTOBER 8 2006 WHEN THE HIGH WAS 75. CMS && .AVIATION DISCUSSION REGARDING 18Z TAFS... 1252 PM CDT MAIN AVIATION FCST FOCUS IS WITH EVENTUAL APPROACH OF COLD FRONT WEDNESDAY MORNING...AND POTENTIAL FOR IFR/LIFR CONDITIONS AS WIND SHIFTS NE OFF COOL LAKE MICHIGAN INTO MOIST LLVL AIR ALONG/SOUTH OF FRONT. BREEZY SWLY LLVL FLOW THIS AFTN AHEAD OF SFC TROF/COLD FRONT NOW FROM CENTRAL ONT TO KSUX VCNTY. 12Z RAOBS AND RECENT ACARS SNDGS INDICATE 30-40 KT WINDS JUST ABOVE SFC...WHICH SFC OBS SHOW IS NOW BEGINNING TO MIX DOWN TO GROUND LVL. WRF BUFKIT MOMENTUM TRANSFER INDICATES 25 KTS A GOOD APPROXIMATE GUST MAGNITUDE...PERHAPS A LITTLE HIGHER IF FAIRLY DENSE CIRRUS SHIELD THINS OUT. GRADIENT WEAKENS A BIT TNGT AS SFC TROF SETTLES ACROSS WI/IA...WHICH ALONG WITH DIURNAL TEMP DECREASE SHOULD RESULT IN LOSS OF STRONGER GUSTS AROUND SUNSET. MODELS APPEAR TO BE FLIP/FLOPPING SLIGHTLY WITH TIMING OF COLD FRONT SAGGING INTO NORTHERN IL. 12Z RUNS OF WRF/GFS BRING FRONT INTO NRN IL JUST BEFORE 12Z...WITH THERMAL GRADIENT ALONG COLD LAKE MICHIGAN EXPECTED TO ALLOW FRONT TO SLIDE FAIRLY QUICKLY SOUTH OF THE LAKE DURG THE MORNING. ULTIMATE FROPA WILL DEPEND ON SMALL SCALE INTERACTION OF BOUNDARY/TEMP GRADIENT ALONG LAKE THOUGH THIS TIMING APPEARS REASONABLE FOR NOW...AND WILL INDICATE WIND SHIFT IN 12-13Z PERIOD ACROSS TERMINALS. WITH WIND TURNING NORTHEAST...POTENTIAL FOR IFR/LIFR CONDITIONS TO DVLP AT LEAST INITIALLY BEHIND FROPA...AS COLD LLVL AIR OFF LAKE IMPINGES ON 50+ DEG SFC DEWPOINTS IN WRM/MOIST LLVL CONDITIONS ALONG/S OF FRONT. FULL RESOLUTION BUFFER FCST SNDGS FROM WRF INDICATE CIGS DVLPG IN 300-500 FT RANGE...AND VARIOUS MOS GUIDANCE ALSO HINTING AT LOW CIG/VIS CONDITIONS. SOME DZ LIKELY AS WELL IN WEAKLY CONVERGENT SATURATED BOUNDARY LAYER. HAVE TRIED TO INDICATE SOME IMPROVEMENT TO HIGHER IFR BY LATER MORNING. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...NONE. && $$
AREA FORECAST DISCUSSION...CORR
NWS LOUISVILLE KY
628 AM EDT WED MAR 14 2007 .AVIATION (12Z TAFS)... 40 KNOT WINDS SHOWING UP ON VWP AT FORT KNOX AT 2000 FEET AT 10Z. RECENT ACARS SOUNDING SHOWING 35 KNOTS AT THAT LEVEL. AS THE WINDS ALOFT DECREASE A BIT AND SURFACE WINDS INCREASE THE LLWS OVER THE REGION EARLY THIS MORNING WILL DIMINISH. WE WILL HAVE SEVERAL DRY HOURS BEFORE THE NEXT UPPER LEVEL DISTURBANCE COMES IN FROM THE SOUTHWEST AND BRINGS ANOTHER ROUND OF SHOWERS WITH IT. EXPECT SHOWERS AND THUNDERSTORMS NEAR THE TAF SITES LATE THIS AFTERNOON INTO EARLY THIS EVENING. THE BEST CHANCE FOR THUNDER WILL BE AFTER 21Z AND THIS IS REFLECTED IN THE TAFS BY INCLUDING A CB CLOUD TYPE. BEST CHANCES FOR SHOWERY WEATHER WILL BE AT SDF AND LEX AS THOSE LOCATIONS ARE INFLUENCED BY BOTH THE UPPER LEVEL DISTURBANCE AND A SURFACE COLD FRONT THAT WILL BE DROPPING SOUTHWARD INTO THE OHIO VALLEY. 13 .SHORT TERM (TODAY AND TONIGHT)... UPPER VORT PRODUCING SCATTERED SHOWERS ACROSS THE LOUISVILLE FORECAST AREA AT 06Z WILL CONTINUE ITS MARCH TO THE NORTHEAST AND WILL TAKE ITS SHOWERS OUT OF OUR AREA EARLY THIS MORNING. WE SHOULD THEN HAVE SEVERAL MOSTLY DRY HOURS FROM MID MORNING INTO EARLY AFTERNOON. UPPER LOW OVER TEXAS WILL CONTINUE TO EDGE SLOWLY EAST...CROSSING TEXAS TODAY AND ENTERING THE LOWER MISSISSIPPI VALLEY TONIGHT. IT WILL SEND ANOTHER SMALL VORT MAX NORTHEAST TODAY...CROSSING CENTRAL KENTUCKY LATE THIS AFTERNOON AND THIS EVENING. THIS FEATURE WILL HELP TO SPARK OFF SHOWERS AND THUNDERSTORMS. IN ADDITION...TONIGHT AN EAST-WEST COLD FRONT WILL DROP SOUTH OUT OF THE MIDWEST AND GREAT LAKES INTO THE OHIO VALLEY. TIMING DIFFERENCES NOTED BY THE DAY SHIFT YESTERDAY CONTINUE...WITH THE NAM12 ABOUT 8 HOURS SLOWER THAN THE GFS. MREF IS ALSO SLOWER THAN THE OPERATIONAL GFS. USING A MREF/SREF BLEND PUTS THE COLD FRONT ALONG OR JUST ON THE INDIANA SIDE OF THE OHIO RIVER BY 12Z THURSDAY MORNING. AS A RESULT WILL LEAN TOWARDS THE WARMER MET NUMBERS FOR LOWS TONIGHT. BETWEEN THE UPPER SYSTEM MOVING OVERHEAD LATER TODAY AND THE COLD FRONT APPROACHING TONIGHT SHOWERS AND THUNDERSTORMS ARE A GOOD BET. THE STORM PREDICTION CENTER HAS PLACED LOCATIONS ALONG AND NORTH OF THE OHIO RIVER IN A SLIGHT RISK FOR SEVERE STORMS. IT APPEARS HOWEVER TO BE A RATHER MARGINAL SET-UP FOR SEVERE WEATHER. LIFTED INDICES AND SHOWALTER INDEX NUMBERS BOTTOMING OUT AROUND -1 OR -2 THIS AFTERNOON WITH TOTAL TOTALS OF 45 TO 50...WEAK CAPE...AND SHALLOW MID-LEVEL LAPSE RATES SUGGEST THUNDERSTORMS ARE A POSSIBILITY BUT THE CHANCE FOR SEVERE SEEMS SMALL. BEST TIME FOR THUNDERSTORMS WILL BE LATE THIS AFTERNOON AS SHEAR PEAKS. CHANCES SHOULD THEN DIMINISH FURTHER ONCE THE SUN SETS. LOW LEVEL JET DOES CRANK UP THIS AFTERNOON AND THE WET BULB ZERO HEIGHT WILL BE AROUND 9000 FEET SO THE STRONGEST STORMS MAY BE ABLE TO PRODUCE SOME GUSTY WINDS AND HAIL. TEMPERATURES TODAY WILL BE TRICKY. LOUISVILLE WAS STILL 70 DEGREES AT 100 AM BEFORE SHOWERS MOVED IN AND DROPPED THE TEMPERATURE TO 63...WITH MIDDLE 60S REPORTED THROUGHOUT THE REST OF THE FORECAST AREA AS WELL. AS OPPOSED TO YESTERDAY...TODAY WILL HAVE COPIOUS AMOUNTS OF CLOUD COVER. HOWEVER A FEW BREAKS WILL BE POSSIBLE BETWEEN THIS MORNING/S AND THIS AFTERNOON/S SHOWERS. WILL ALLOW READINGS TO CLIMB ABOUT TEN DEGREES...INTO THE MIDDLE 70S. 13 .LONG TERM (THURSDAY THROUGH TUESDAY)... THURSDAY THROUGH FRIDAY NIGHT... THIS PERIOD WILL BE THE MAIN FOCUS OF THE EXTENDED FORECAST AS DECENT COLD FRONT WILL DROP SOUTH AND BRING A PERIOD OF SHOWERS AND STORMS TO THE OHIO VALLEY. 00Z GFS AND NAM-WRF RUNS CONTINUE TO HAVE TIMING DIFFERENCES WITH THE ACTUAL FRONTAL PASSAGE. GFS SOLUTIONS CONTINUE TO BE CONSISTENT WITH PREVIOUS RUNS ON A THURSDAY MORNING FRONTAL PASSAGE WHILE THE NAM-WRF IS SOME 12 HOURS LATER. 21Z SREF SOLUTIONS ARE FAIRLY CONSISTENT WITH THE YESTERDAYS 09Z SOLUTION WHICH IS DOWN THE MIDDLE OF BOTH THE OP GFS AND NAM RUNS. THEREFORE WILL CONTINUE TO LEAN THE TOWARD THIS SOLUTION FOR THE FORECAST. USING THE 21Z SREF SOLUTION SFC FRONTAL BOUNDARY LOOKS TO CROSS THROUGH THE AREA DURING THE DAY ON THURSDAY. EXTENSIVE CLOUDINESS AND SCATTERED PRECIPITATION ARE EXPECTED THURSDAY MORNING AND WILL LIKELY LIMIT SFC BASED INSTABILITY. ADDITIONALLY...LAPSE RATES ARE NOT ALL THAT GREAT AS COOLER AIR ALOFT IS DISPLACED FURTHER NW OF THE AREA. LOW-LEVEL FLOW AHEAD OF THE FRONT STILL LOOKS TO BE IN THE AREA OF 35-40 KTS...THEREFORE SOME GUSTY WINDS WILL BE POSSIBLE WITH ANY CONVECTION THAT CAN GET GOING. HOWEVER...OVERALL THREAT OF ORGANIZED SEVERE APPEARS QUITE DIMINISHED AS OF THIS TIME. BEST FORCING WILL BE ALONG SAID FRONTAL BOUNDARY AND BASED ON 21Z SREF HAVE GONE AHEAD AND BUMPED POPS UP TO THE HIGH END OF THE LIKELY CATEGORY. TEMPERATURES FOR THURSDAY WILL BE A CHALLENGE DUE TO CLOUD COVER AND PRECIPITATION. I HAVE LOWERED TEMPS BY A DEGREE OR TWO WITH LOWER 60S ACROSS SOUTHERN INDIANA AND MID TO UPPER 60S ACROSS CENTRAL AND SOUTHERN KENTUCKY. I ANTICIPATE FALLING TEMPERATURES QUICKLY AFTER FRONTAL PASSAGE. LOWS THURSDAY NIGHT WILL DROP INTO THE UPPER 30S ACROSS SOUTHERN INDIANA AND PORTIONS OF NORTH CENTRAL KY. WARMER READINGS WILL BE FURTHER SOUTH ALONG THE KY/TN BORDER WITH MID TO UPPER 40S. FOR FRIDAY...POST FRONTAL PRECIPITATION WILL CONTINUE TO MOVE EAST AND OUT OF THE AREA. WILL MAINTAIN A SMALL CHANCE OF PRECIPITATION FOR FRIDAY MORNING ACROSS THE EASTERN SECTIONS. MOSTLY CLOUDY SKIES ARE EXPECTED THROUGH MUCH OF THE DAY WITH SOME PARTIAL CLEARING POSSIBLE BY LATE AFTERNOON. CLOUDS WILL KEEP TEMPS DOWN WITH HIGHS ONLY WARMING INTO THE UPPER 40S TO AROUND 50. A RETURN TO COLDER TEMPS IS EXPECTED FRIDAY NIGHT WITH OVERNIGHT LOWS DIPPING INTO THE UPPER 20S TO AROUND 30. SATURDAY THROUGH SUNDAY... MODEL CONSENSUS SOLUTION SUGGESTS DRY CONDITIONS THROUGH THIS PORTION OF THE FORECAST PERIOD. OHIO VALLEY TO REMAIN IN GENERAL NORTHWEST FLOW PATTERN. LAST FEW RUNS OF THE GFS HAVE BEEN SUGGESTING THAT WEAK VORT WITHIN THE FLOW MAY TRIGGER SOME LIGHT PRECIPITATION JUST TO OUR NORTHEAST DURING THE DAY ON SATURDAY. A STRONGER SYSTEM MAY DROP DOWN INTO THE REGION BY SUNDAY BRINGING LIGHT PRECIP. THERMAL PROFILES SUPPORT LIQUID PRECIPITATION AT THIS TIME. FOR NOW WILL HOLD OFF ON MAKING MAJOR ADJUSTMENTS TO THE FORECAST PERIOD AND WAIT TO SEE WHAT THE ENSEMBLES RUNS REVEAL. CURRENT FORECAST TEMPS LOOK OK FOR NOW...WITH HIGHS IN THE MID 40S IN THE NORTHEAST SECTIONS TO THE UPPER 40S AND LOWER 50S ACROSS THE SOUTHWEST. TEMPERATURES FOR SUNDAY MAY NEED TO BE TRENDED DOWN SOME AS 00Z GFS RAW NUMBERS SUPPORT COOLER TEMP TRENDS. -MJ SUNDAY NIGHT THROUGH TUESDAY... NO CHANGES MADE FOR THIS PART OF THE FORECAST PERIOD. PREVIOUS DISCUSSION FOLLOWS... BASING THE LAST TWO DAYS OF THE FCST PRIMARILY ON BLEND OF 0Z NCEP ENS MEAN AND ECMWF...WHICH SHOW UPPER TROF LIFTING NE WITH STRONG SW LOW LEVEL FLOW DEVELOPING OVER THE OHIO VALLEY. THIS WILL HELP TEMPS RISE QUICKLY BACK INTO THE 60S (ABOVE NORMAL) FOR MON AND TUES. A SFC FRONT DEPICTED BY BOTH MODEL SOLNS IS EXPECTED TO DROP S INTO THE OHIO VALLEY SOMETIME LATE MONDAY...PROVIDING A CHANCE FOR SHOWERS...SLIGHT CHANCES MONDAY...BETTER CHANCES INTO TUESDAY. THERE COULD BE SOME THUNDER INVOLVED AS WELL BUT AMT OF INSTABILITY THAT CAN DEVELOP IS QUESTIONABLE AT THIS TIME. CS && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1300 AM EDT WED MAR 14 2007 .MORNING UPDATE... INITIAL SHORTWAVE THAT BROUGHT RAIN EARLIER THIS MORNING ACROSS KENTUCKY HAS MOVED INTO OHIO. IN ITS WAKE...WEAK SUBSIDENCE HAS PRODUCED PARTLY CLOUDY SKIES AND MILD TEMPERATURES. LOCAL SOUNDINGS AND SATELLITE IMAGERY SHOW THAT ALTHOUGH SOME INSTABILITY WILL DEVELOP THIS AFTERNOON...A LACK OF ANY UPPER LEVEL SUPPORT MAY DELAY ANY THUNDERSTORM DEVELOPMENT UNTIL LATE THIS AFTERNOON OR EVENING. HAVE DELAYED LIKELY THUNDERSTORM DEVELOPMENT UNTIL THIS EVENING...AND TRENDED SKIES TOWARDS PARTLY CLOUDY. JSD .SHORT TERM (TODAY AND TONIGHT)... UPPER VORT PRODUCING SCATTERED SHOWERS ACROSS THE LOUISVILLE FORECAST AREA AT 06Z WILL CONTINUE ITS MARCH TO THE NORTHEAST AND WILL TAKE ITS SHOWERS OUT OF OUR AREA EARLY THIS MORNING. WE SHOULD THEN HAVE SEVERAL MOSTLY DRY HOURS FROM MID MORNING INTO EARLY AFTERNOON. UPPER LOW OVER TEXAS WILL CONTINUE TO EDGE SLOWLY EAST...CROSSING TEXAS TODAY AND ENTERING THE LOWER MISSISSIPPI VALLEY TONIGHT. IT WILL SEND ANOTHER SMALL VORT MAX NORTHEAST TODAY...CROSSING CENTRAL KENTUCKY LATE THIS AFTERNOON AND THIS EVENING. THIS FEATURE WILL HELP TO SPARK OFF SHOWERS AND THUNDERSTORMS. IN ADDITION...TONIGHT AN EAST-WEST COLD FRONT WILL DROP SOUTH OUT OF THE MIDWEST AND GREAT LAKES INTO THE OHIO VALLEY. TIMING DIFFERENCES NOTED BY THE DAY SHIFT YESTERDAY CONTINUE...WITH THE NAM12 ABOUT 8 HOURS SLOWER THAN THE GFS. MREF IS ALSO SLOWER THAN THE OPERATIONAL GFS. USING A MREF/SREF BLEND PUTS THE COLD FRONT ALONG OR JUST ON THE INDIANA SIDE OF THE OHIO RIVER BY 12Z THURSDAY MORNING. AS A RESULT WILL LEAN TOWARDS THE WARMER MET NUMBERS FOR LOWS TONIGHT. BETWEEN THE UPPER SYSTEM MOVING OVERHEAD LATER TODAY AND THE COLD FRONT APPROACHING TONIGHT SHOWERS AND THUNDERSTORMS ARE A GOOD BET. THE STORM PREDICTION CENTER HAS PLACED LOCATIONS ALONG AND NORTH OF THE OHIO RIVER IN A SLIGHT RISK FOR SEVERE STORMS. IT APPEARS HOWEVER TO BE A RATHER MARGINAL SET-UP FOR SEVERE WEATHER. LIFTED INDICES AND SHOWALTER INDEX NUMBERS BOTTOMING OUT AROUND -1 OR -2 THIS AFTERNOON WITH TOTAL TOTALS OF 45 TO 50...WEAK CAPE...AND SHALLOW MID-LEVEL LAPSE RATES SUGGEST THUNDERSTORMS ARE A POSSIBILITY BUT THE CHANCE FOR SEVERE SEEMS SMALL. BEST TIME FOR THUNDERSTORMS WILL BE LATE THIS AFTERNOON AS SHEAR PEAKS. CHANCES SHOULD THEN DIMINISH FURTHER ONCE THE SUN SETS. LOW LEVEL JET DOES CRANK UP THIS AFTERNOON AND THE WET BULB ZERO HEIGHT WILL BE AROUND 9000 FEET SO THE STRONGEST STORMS MAY BE ABLE TO PRODUCE SOME GUSTY WINDS AND HAIL. TEMPERATURES TODAY WILL BE TRICKY. LOUISVILLE WAS STILL 70 DEGREES AT 100 AM BEFORE SHOWERS MOVED IN AND DROPPED THE TEMPERATURE TO 63...WITH MIDDLE 60S REPORTED THROUGHOUT THE REST OF THE FORECAST AREA AS WELL. AS OPPOSED TO YESTERDAY...TODAY WILL HAVE COPIOUS AMOUNTS OF CLOUD COVER. HOWEVER A FEW BREAKS WILL BE POSSIBLE BETWEEN THIS MORNING/S AND THIS AFTERNOON/S SHOWERS. WILL ALLOW READINGS TO CLIMB ABOUT TEN DEGREES...INTO THE MIDDLE 70S. 13 .LONG TERM (THURSDAY THROUGH TUESDAY)... THURSDAY THROUGH FRIDAY NIGHT... THIS PERIOD WILL BE THE MAIN FOCUS OF THE EXTENDED FORECAST AS DECENT COLD FRONT WILL DROP SOUTH AND BRING A PERIOD OF SHOWERS AND STORMS TO THE OHIO VALLEY. 00Z GFS AND NAM-WRF RUNS CONTINUE TO HAVE TIMING DIFFERENCES WITH THE ACTUAL FRONTAL PASSAGE. GFS SOLUTIONS CONTINUE TO BE CONSISTENT WITH PREVIOUS RUNS ON A THURSDAY MORNING FRONTAL PASSAGE WHILE THE NAM-WRF IS SOME 12 HOURS LATER. 21Z SREF SOLUTIONS ARE FAIRLY CONSISTENT WITH THE YESTERDAYS 09Z SOLUTION WHICH IS DOWN THE MIDDLE OF BOTH THE OP GFS AND NAM RUNS. THEREFORE WILL CONTINUE TO LEAN THE TOWARD THIS SOLUTION FOR THE FORECAST. USING THE 21Z SREF SOLUTION SFC FRONTAL BOUNDARY LOOKS TO CROSS THROUGH THE AREA DURING THE DAY ON THURSDAY. EXTENSIVE CLOUDINESS AND SCATTERED PRECIPITATION ARE EXPECTED THURSDAY MORNING AND WILL LIKELY LIMIT SFC BASED INSTABILITY. ADDITIONALLY...LAPSE RATES ARE NOT ALL THAT GREAT AS COOLER AIR ALOFT IS DISPLACED FURTHER NW OF THE AREA. LOW-LEVEL FLOW AHEAD OF THE FRONT STILL LOOKS TO BE IN THE AREA OF 35-40 KTS...THEREFORE SOME GUSTY WINDS WILL BE POSSIBLE WITH ANY CONVECTION THAT CAN GET GOING. HOWEVER...OVERALL THREAT OF ORGANIZED SEVERE APPEARS QUITE DIMINISHED AS OF THIS TIME. BEST FORCING WILL BE ALONG SAID FRONTAL BOUNDARY AND BASED ON 21Z SREF HAVE GONE AHEAD AND BUMPED POPS UP TO THE HIGH END OF THE LIKELY CATEGORY. TEMPERATURES FOR THURSDAY WILL BE A CHALLENGE DUE TO CLOUD COVER AND PRECIPITATION. I HAVE LOWERED TEMPS BY A DEGREE OR TWO WITH LOWER 60S ACROSS SOUTHERN INDIANA AND MID TO UPPER 60S ACROSS CENTRAL AND SOUTHERN KENTUCKY. I ANTICIPATE FALLING TEMPERATURES QUICKLY AFTER FRONTAL PASSAGE. LOWS THURSDAY NIGHT WILL DROP INTO THE UPPER 30S ACROSS SOUTHERN INDIANA AND PORTIONS OF NORTH CENTRAL KY. WARMER READINGS WILL BE FURTHER SOUTH ALONG THE KY/TN BORDER WITH MID TO UPPER 40S. FOR FRIDAY...POST FRONTAL PRECIPITATION WILL CONTINUE TO MOVE EAST AND OUT OF THE AREA. WILL MAINTAIN A SMALL CHANCE OF PRECIPITATION FOR FRIDAY MORNING ACROSS THE EASTERN SECTIONS. MOSTLY CLOUDY SKIES ARE EXPECTED THROUGH MUCH OF THE DAY WITH SOME PARTIAL CLEARING POSSIBLE BY LATE AFTERNOON. CLOUDS WILL KEEP TEMPS DOWN WITH HIGHS ONLY WARMING INTO THE UPPER 40S TO AROUND 50. A RETURN TO COLDER TEMPS IS EXPECTED FRIDAY NIGHT WITH OVERNIGHT LOWS DIPPING INTO THE UPPER 20S TO AROUND 30. SATURDAY THROUGH SUNDAY... MODEL CONSENSUS SOLUTION SUGGESTS DRY CONDITIONS THROUGH THIS PORTION OF THE FORECAST PERIOD. OHIO VALLEY TO REMAIN IN GENERAL NORTHWEST FLOW PATTERN. LAST FEW RUNS OF THE GFS HAVE BEEN SUGGESTING THAT WEAK VORT WITHIN THE FLOW MAY TRIGGER SOME LIGHT PRECIPITATION JUST TO OUR NORTHEAST DURING THE DAY ON SATURDAY. A STRONGER SYSTEM MAY DROP DOWN INTO THE REGION BY SUNDAY BRINGING LIGHT PRECIP. THERMAL PROFILES SUPPORT LIQUID PRECIPITATION AT THIS TIME. FOR NOW WILL HOLD OFF ON MAKING MAJOR ADJUSTMENTS TO THE FORECAST PERIOD AND WAIT TO SEE WHAT THE ENSEMBLES RUNS REVEAL. CURRENT FORECAST TEMPS LOOK OK FOR NOW...WITH HIGHS IN THE MID 40S IN THE NORTHEAST SECTIONS TO THE UPPER 40S AND LOWER 50S ACROSS THE SOUTHWEST. TEMPERATURES FOR SUNDAY MAY NEED TO BE TRENDED DOWN SOME AS 00Z GFS RAW NUMBERS SUPPORT COOLER TEMP TRENDS. -MJ SUNDAY NIGHT THROUGH TUESDAY... NO CHANGES MADE FOR THIS PART OF THE FORECAST PERIOD. PREVIOUS DISCUSSION FOLLOWS... BASING THE LAST TWO DAYS OF THE FCST PRIMARILY ON BLEND OF 0Z NCEP ENS MEAN AND ECMWF...WHICH SHOW UPPER TROF LIFTING NE WITH STRONG SW LOW LEVEL FLOW DEVELOPING OVER THE OHIO VALLEY. THIS WILL HELP TEMPS RISE QUICKLY BACK INTO THE 60S (ABOVE NORMAL) FOR MON AND TUES. A SFC FRONT DEPICTED BY BOTH MODEL SOLNS IS EXPECTED TO DROP S INTO THE OHIO VALLEY SOMETIME LATE MONDAY...PROVIDING A CHANCE FOR SHOWERS...SLIGHT CHANCES MONDAY...BETTER CHANCES INTO TUESDAY. THERE COULD BE SOME THUNDER INVOLVED AS WELL BUT AMT OF INSTABILITY THAT CAN DEVELOP IS QUESTIONABLE AT THIS TIME. CS && .AVIATION (12Z TAFS)... 40 KNOT WINDS SHOWING UP ON VWP AT FORT KNOX AT 2000 FEET AT 10Z. RECENT ACARS SOUNDING SHOWING 35 KNOTS AT THAT LEVEL. AS THE WINDS ALOFT DECREASE A BIT AND SURFACE WINDS INCREASE THE LLWS OVER THE REGION EARLY THIS MORNING WILL DIMINISH. WE WILL HAVE SEVERAL DRY HOURS BEFORE THE NEXT UPPER LEVEL DISTURBANCE COMES IN FROM THE SOUTHWEST AND BRINGS ANOTHER ROUND OF SHOWERS WITH IT. EXPECT SHOWERS AND THUNDERSTORMS NEAR THE TAF SITES LATE THIS AFTERNOON INTO EARLY THIS EVENING. THE BEST CHANCE FOR THUNDER WILL BE AFTER 21Z AND THIS IS REFLECTED IN THE TAFS BY INCLUDING A CB CLOUD TYPE. BEST CHANCES FOR SHOWERY WEATHER WILL BE AT SDF AND LEX AS THOSE LOCATIONS ARE INFLUENCED BY BOTH THE UPPER LEVEL DISTURBANCE AND A SURFACE COLD FRONT THAT WILL BE DROPPING SOUTHWARD INTO THE OHIO VALLEY. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$