Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 02/09/09

AREA FORECAST DISCUSSION
NWS LINCOLN IL
203 PM CST SUN FEB 8 2009 .DISCUSSION... ISSUED 145 PM CST SUN FEB 8 2009 HIGH PRESSURE CENTERED OVER CENTRAL IL EARLY THIS AFTERNOON WAS FORECAST WELL BY THE MODELS...UNFORTUNATELY THE LOW CLOUDS THAT ACCOMPANIED THE HIGH WERE NOT...AND AS OF THE 12Z RUNS WERE STILL NOT HANDLED VERY WELL. FAIRLY STRONG LOW LVL INVERSION IN PLACE ACRS THE FORECAST AREA AND EXCPT FOR THE FAR EAST AND SOUTHEAST WHICH HAS ENJOYED SOME SUN THIS AFTN...THE REMAINDER OF THE AREA REMAINS UNDER CLOUD COVER. VSBL SATELLITE TRENDS INDICATING SOME EROSION OF THE CLOUDS FRM THE SOUTHWEST WITH BNDRY LAYER WINDS LIGHT AND VARIABLE INDICATING THE CLOUD DECK WL BE SLOW TO PULL OUT. THE MAIN FORECAST CONCERNS WILL BE THE TIMING OF THE SHOWERS AND THUNDERSTORMS INTO THE FORECAST AREA MONDAY AND AGAIN LATE TUE NIGHT AND WEDNESDAY AS AN ACTIVE SOUTHWEST FLOW PATTERN HOLDS ACRS THE AREA THROUGH THE WEEK. SHORT TERM...TONIGHT THROUGH WEDNESDAY WL TEND TO LEAN MORE TWDS THE NAM-WRF MODEL THIS PERIOD...ESP WITH ITS HANDLING OF THE LATE TUE AND WED SYSTEM AS IT APPEARS THE MODEL IS LESS AFFECTED BY CONVECTIVE FEEDBACK COMPARED WITH THE GFS. AS A RESULT...THE NAM HAS TRENDED A BIT SLOWER AND MORE COMPACT WITH THE SFC LOW FORECAST TO PUSH INTO CNTRL IL WED AFTN. CLOUD SHIELD THAT IS DOMINATING ALL BUT THE EAST AND SOUTHEAST THIS AFTN WL CONTINUE TO SHRINK FROM THE SOUTH AND SOUTHWEST AND THEN LIFT NORTH OVERNIGHT AS BNDRY LAYER WNDS BECOME SOUTHEAST. HOWEVER...A LARGE AREA OF CLOUDS ACRS MO WILL TAKE ITS PLACE AS THE SHORTWAVE THAT WILL AFFECT OUR AREA MONDAY AFTN AND EVENING PUSHES INTO THE SRN PLAINS. THE BOUNDARY THAT WENT THRU OUR AREA YESTERDAY EVENING WAS LOCATED ACRS SRN MO INTO NRN OK AND IS FORECAST TO SLOWLY PUSH NWD LATE TNT. INCRG MOIST SRLY FLOW INTO THE BNDRY FCST BY ALL MODELS WITH SOME FAIRLY DECENT ISENT LIFT NOTED ON THE 295K SFC AFTR 06Z ACRS OUR WRN AREAS...WHICH MAY LEAD TO SOME PATCHY DRIZZLE OR EVEN SOME ISOLD SHOWERS. THE NEGATIVE TILT TROF IS FORECAST TO EJECT QUICKLY NNE INTO THE MO VALLEY BY MONDAY AFTERNOON WITH A SCT-BKN LINE OF SHOWERS AND SCATTERED THUNDERSTORMS RACING NE INTO OUR AREA BY LATE AFTN AND EVENING. BUFKIT SOUNDINGS ACRS OUR WRN AREAS JUST AHEAD OF THIS BAND OF SHOWERS WAS INDICATING 55-60 KTS JUST OFF THE SURFACE DURING THE LATE AFTN HOURS AS THE DEEP TROF PUSHES TO OUR WEST. ALTHOUGH INSTABILITY IS NON-EXISTANT ACRS OUR AREA...A FEW OF THE HEAVIER SHOWERS MAY BRING SOME OF THE STRONGER WINDS DOWN TO THE SFC LATE IN THE AFTN AND EVENING...IN ADDITION TO THE STRONG GRADIENT WINDS THAT WILL INFLUENCE THE AREA. STRONG DRYING AT THE LOW AND MID LEVELS WILL PUSH INTO WRN IL EARLY MONDAY EVENING AND COVER THE REMAINDER OF THE FCST AREA AFTR MIDNIGHT. WL PUSH THE RAIN CHANCES OUT A BIT QUICKER IN THE EAST OVERNIGHT AS A RESULT. QUIET WEATHER EXPECTED ON TUESDAY AS A DRY SOUTHWESTERLY FLOW PREVAILS ACRS THE FORECAST AREA. 850 TEMPS ARE FORECAST TO BE ARND +8C DURING THE DAY. THAT COUPLED WITH SUNSHINE AND A GUSTY SOUTHWEST WIND SHOULD ALLOW TEMPERATURES TO CLIMB INTO THE 60S MOST AREAS...SOME 25 TO 30 DEGREES ABOVE NORMAL FOR THE SECOND WEEK IN FEBRUARY. RECORD TEMPERATURES...EXCPT FOR CMI WHICH IS 68 DEGREES...ARE IN THE 70 TO 75 DEGREE RANGE FOR TUESDAY. THE NEXT AND MORE SIGNIFICANT SHORTWAVE IS FORECAST TO PUSH INTO THE SRN PLAINS TUE NIGHT WITH WIDESPREAD WARM ADVECTION PRECIP SPREADING QUICKLY NORTHEAST INTO THE MID-MISSISSIPPI VALLEY. AGAIN WITH THE SLOWER NAM-WRF SOLUTION PREFERRED...THE SFC LOW IS FORECAST TO DEEPEN AS IT PUSHES INTO CNTRL MO WED MRNG AND THEN SHIFT NE INTO WRN LOWER MICHIGAN BY WED NIGHT. UNLIKE THE EARLY WEEK SYSTEM...THE STRONG UPPER LEVEL DYNAMICS ARE THIS TIME FORECAST TO SHIFT RIGHT OVER THE FORECAST AREA ON WEDNEDAY WITH THE THREAT FOR HEAVY RAIN...AND POTENTIALLY SEVERE WEATHER WED AFTN...ESP IF THE SLOWER AND FURTHER WEST TRACK OF THE NAM-WRF VERIFIES. VERY FAVORABLE JET DYNAMICS AS MODELS INDICATE A COUPLED JET STRUCTURE AT H250 LATE TUE NIGHT INTO WED MORNING ENHANCING THE UPWARD VERTICAL MOTION/HEAVY RAIN THREAT IN OUR AREA. RAINFALL AMOUNTS IN THE 2-3 INCH CATEGORY CAN NOT BE RULED OUT BY WED EVENING BASED ON THE STRONG MOISTURE TRANSPORT FROM THE GULF OF MEXICO AHEAD OF THE DEEPENING UPPER LOW. LONG TERM...THURSDAY THROUGH SUNDAY ACTIVE SOUTHWEST FLOW WILL CONTINUE THIS PERIOD WITH SEVERAL SHORTWAVES TO DEAL WITH FOR OUR FORECAST AREA. ALTHOUGH THERE WERE SIGNIFICANT MODEL DIFFERENCES WITH THE LATE WEEK SYSTEM... WL LEAN ON THE MORE CONSISTENT ECWMF IN BRINGING OUR NEXT CHANCE FOR PRECIP INTO THE FORECAST AREA LATE FRIDAY NIGHT INTO SATURDAY. WITH A FURTHER SOUTH TRACK INDICATED BY THE MODEL...THERE APPEARS TO BE ENOUGH LOW LEVEL COLD AIR IN PLACE TO CREATE A PTYPE PROBLEM. FOR NOW...WL INDICATE SNOW CHANCES NORTH AND RAIN/SNOW CHANCES FURTHER SOUTH AND SEE HOW THE MODEL HANDLES THIS PARTICULAR SYSTEM OVR THE NEXT SEVERAL RUNS. MEDIUM AND LONGER RANGE MODELS CONTINUE TO INDICATE ABOVE NORMAL TEMPERATURES WITH A CONTINUATION OF ABOVE NORMAL PRECIP AS WE HEAD INTO NEXT WEEKEND WITH ANOTHER POTENTIAL STORM LATE IN THE WEEKEND OR JUST BEYOND THIS PERIOD. ENSEMBLES TRENDING TOWARDS A MORE SUPPRESSED LOOK TO THE ACTIVE SUBTROPICAL JET LATE IN THIS PERIOD WHICH WOULD TEND TO PUSH THE THE SFC LOWS FURTHER SOUTH AS WELL. SMITH && .AVIATION... ISSUED 1128 AM CST SUN FEB 8 2009 LOW CLOUDS ARE THE MAIN PROBLEM THIS FORECAST PERIOD. STRATUS DECK OF 1000 FEET OR LESS WAS ONLY SLOWLY ERODING FROM EAST TO WEST...WITH THE EDGE OF THE DECK JUST WEST OF KCMI. MODEL AND TAMDAR SOUNDINGS...AS WELL AS PILOT REPORTS...INDICATE THIS DECK IS ABOUT 500 OR SO FEET THICK. WHILE THE MODEL SOUNDINGS INDICATE THIS SHOULD BE BREAKING UP THIS AFTERNOON...TAF FORECASTS WILL BE MUCH MORE PESSIMISTIC AT MOST SITES AND KEEP AT LEAST LOW MVFR CONDITIONS WELL INTO THE EVENING. EASTERN SITES...IE KBMI/KCMI/KDEC...WILL TREND THE CLOUD BREAKUP LATE AFTERNOON OR EARLY EVENING. AM CURRENTLY EXPECTING MORE MVFR CONDITIONS BY MONDAY MORNING...BUT WOULD NOT BE SURPRISED TO SEE THEM DEVELOP A FEW HOURS EARLIER. LIGHT AND VARIABLE WINDS WILL TURN SOUTHEAST AND INCREASE OVERNIGHT...AS HIGH PRESSURE DEPARTS THE AREA. EXPECTING BREEZIER CONDITIONS TO DEVELOP MONDAY MORNING WITH SUSTAINED WINDS IN THE 10-15 KNOT RANGE. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1129 AM CST SUN FEB 8 2009 .DISCUSSION... ISSUED 1042 AM CST SUN FEB 8 2009 LOW CLOUDS COVERING MUCH OF THE CWA THIS MORNING...WITH THE CLEARING LINE ALONG I-57 AND EDGING WESTWARD. THIS HAS KEPT TEMPERATURES COOLER UNDERNEATH THE CLOUDS...WITH 30-35 DEGREES PREVALENT BY LATE MORNING. AREAS WITH SUNSHINE SOMEWHAT WARMER...WITH LOWER 40S BECOMING MORE COMMON SOUTH OF I-70. CONCERNS WITH THE FORECAST INCLUDE HOW THESE CLOUDS ARE GOING TO INFLUENCE THE AFTERNOON HIGHS. UPDATED THE ZONES/GRIDS A BIT EARLIER TO TONE DOWN THE HIGHS BY A FEW DEGREES...AND BE MORE PESSIMISTIC IN THE CLOUD COVER. WARMEST CONDITIONS TO BE IN THE EASTERN CWA...WHERE THE MOST SUNSHINE WILL OCCUR. MID AND HIGH CLOUDS WILL BE STREAMING OUT OF MISSOURI ATOP OF THE STRATUS DECK...WHICH MAY LIMIT THE AMOUNT OF BREAKUP OF THE LOWER CLOUDS. LATEST RUC SOUNDINGS SHOW A SLOW BREAKUP EARLY THIS AFTERNOON... ALTHOUGH A VERY SHARP INVERSION WILL REMAIN IN PLACE. GEELHART && .AVIATION... ISSUED 1128 AM CST SUN FEB 8 2009 LOW CLOUDS ARE THE MAIN PROBLEM THIS FORECAST PERIOD. STRATUS DECK OF 1000 FEET OR LESS WAS ONLY SLOWLY ERODING FROM EAST TO WEST...WITH THE EDGE OF THE DECK JUST WEST OF KCMI. MODEL AND TAMDAR SOUNDINGS...AS WELL AS PILOT REPORTS...INDICATE THIS DECK IS ABOUT 500 OR SO FEET THICK. WHILE THE MODEL SOUNDINGS INDICATE THIS SHOULD BE BREAKING UP THIS AFTERNOON...TAF FORECASTS WILL BE MUCH MORE PESSIMISTIC AT MOST SITES AND KEEP AT LEAST LOW MVFR CONDITIONS WELL INTO THE EVENING. EASTERN SITES...IE KBMI/KCMI/KDEC...WILL TREND THE CLOUD BREAKUP LATE AFTERNOON OR EARLY EVENING. AM CURRENTLY EXPECTING MORE MVFR CONDITIONS BY MONDAY MORNING...BUT WOULD NOT BE SURPRISED TO SEE THEM DEVELOP A FEW HOURS EARLIER. LIGHT AND VARIABLE WINDS WILL TURN SOUTHEAST AND INCREASE OVERNIGHT...AS HIGH PRESSURE DEPARTS THE AREA. EXPECTING BREEZIER CONDITIONS TO DEVELOP MONDAY MORNING WITH SUSTAINED WINDS IN THE 10-15 KNOT RANGE. GEELHART && .PREV DISCUSSION... ISSUED 311 AM CST SUN FEB 8 2009 NOT A LOT IN THE WAY OF CHANGES OR IMPROVEMENTS IN THE FORECAST WITH THIS RUN. DEEP LOW PUSHING INTO THE SW COAST OF THE CONUS THIS MORNING. TWO COLD FRONTS MOVING INTO THE MIDWEST ON HPC SFC ANALYSIS THIS MORNING...BRINGING A COUPLE OF SHOTS OF COLD AIR IN FROM CENTRAL CANADA. MAIN ISSUES FOR THE FORECAST REMAIN THE TWO LOW PRESSURE SYSTEMS MOVING THROUGH TOMORROW AND WEDNESDAY...BOTH BRINGING RAIN TO THE MIDWEST. MODELS IN FAIR AGREEMENT THROUGH THE MED RANGE. STILL GOING WITH A COMBINATION OF THE NAM AND THE ECMWF...THOUGH IT DOES BEAR MENTIONING THAT THE FLIP FLOP BETWEEN THE TIMING IN THE 12Z AND 00Z RUNS SEEMS TO BE AFFECTING THE FORECAST. MODELS HAD BEEN PUSHING BACK THE ARRIVAL OF BOTH SYSTEMS...BUT THIS RUN SEEMS TO HAVE STEPPED THE TIMING BACK UP A LITTLE BIT...CLOSER TO LAST NIGHTS SOLUTION. HAVE TRIED TO MAINTAIN A RATHER CONSERVATIVE MIDDLE GROUND FOR THIS FORECAST TO CUT BACK ON THE DISPARITY. SHORT TERM...TODAY AND TOMORROW... TODAY A BIT COOLER THAN YESTERDAY...ESPECIALLY AS NRLY WINDS USHER IN COOL DRY AIR FROM THE UPPER MIDWEST...AND A SWATH OF LLVL STRATUS FORMING ON SATELLITE... SPREADING INTO THE NRN TIER OF THE FA. DIURNAL SWING TO BE KEPT TO A MINIMUM BY SOME CLOUDS OVERNIGHT TONIGHT...AND WAA KICKING IN AT THE SFC AS THE WINDS BECOME A BIT MORE SOUTHEASTERLY THEN SOUTHERLY AHEAD OF A WAVE EJECTING OUT OF THE DESERT SW. THE SFC LOW IS EXPECTED TO BE WELL NORTH AND WEST OF HERE...AND WITH IT THE BETTER DYNAMICS. THAT BEING SAID...MONDAY AFTERNOON AND EARLY EVENING MAY SEE A CHANCE FOR THUNDER AS THE SFC BOUNDARY MAKES ITS WAY ACROSS THE STATE WITH THE BETTER TEMPS AT THE END OF THE DAY. LONG TERM...TUESDAY THROUGH THURSDAY... SHOWERS PUSHING TO THE SOUTH TUESDAY..GIVING A BRIEF BREAK AS SOUTHERLY WINDS START TO MOVE BACK INTO THE FA. TUESDAY SHOULD SEE TEMPS WELL ABOVE NORMAL INTO THE MID 60S AHEAD OF THE NEXT SYSTEM THAT NIGHT AND INTO WEDNESDAY. ANOTHER WAVE PUSHES OUT OF THE SW...TRACKING THE ASSOCIATED SFC LOW DIRECTLY ACROSS CENTRAL ILLINOIS. QPF FIELDS IN THE FORECAST MODELS A LITTLE SUSPICIOUS AS THIS IS MORE OF A SPRING STORM AND THE MODELS STILL LOOK LIKE THEY ARE WORKING OFF OF WINTER PARAMETERIZATION. HAVE BEEN CONSERVATIVE ON THE QPF ESTIMATES AS A RESULT. ONE THING TO CONSIDER IN THE LONGER TERM HOWEVER IS THAT MONDAYS RAIN QPF LIKELY TO CENTER ON THE SERN CWA... AND WEDNESDAYS ON THE NWRN. EITHER WAY...BOTH THE ILLINOIS RIVER VALLEY AND THE FLASHIER RIVERS IN THE SE WILL SEE AN INFLUX OF MORE WATER ON TOP OF SIGNIFICANT SNOW MELT OF LATE. ANYONE WITH INTERESTS ALONG RIVERS SHOULD MONITOR THOSE FORECASTS AS WELL. THURSDAY RETURNS TO DRY WITH MORE MODERATE TEMPS. HJS && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
915 AM CST SAT FEB 7 2009 .DISCUSSION... 915 AM CST QUICK UPDATE TO FORECAST MAINLY TO REMOVE MORNING FOG...DECREASE SKY COVER A BIT...AND TO BUMP TEMPS A LITTLE ACROSS SOUTHERN HALF OF CWA. LOW PRESSURE MOVING ACROSS LAKE SUPERIOR THIS MORNING...WITH COLD FRONT TRAILING ACROSS WISCONSIN INTO SOUTHEAST IOWA. LITTLE IN WAY OF SIGNIFICANT CLOUD COVER OTHER THAN SOME THIN CIRRUS ACROSS WARM SECTOR...WITH EARLY MORNING TEMPS ALREADY IN MID 40S TO LOWER 50S ACROSS FORECAST AREA. BASED ON THESE TRENDS AND PARCEL TRAJECTORY SOURCES FROM YESTERDAY/LAST NIGHT...HAVE WARMED TEMPS A FEW DEGREES/ONE CATEGORY ACROSS SOUTHERN HALF OF CWA WHERE 60 PERHAPS NOT OUT OF REACH. COLD FRONT ALREADY PUSHING INTO NORTHWEST IL SO FAR NORTH/NORTHWEST COUNTIES SO LEFT TEMPS AS IS THERE. RATZER && .PREV DISCUSSION... 330 AM...LITTLE IN THE WAY OF LOW CLOUDS/FOG AND DRIZZLE THIS MORNING. DESPITE WARM/MOIST AIR OVER SNOW...LOW LEVEL MIXING HAS LIKELY BEEN STRONG ENOUGH TO PREVENT LOW VIS/CIGS FROM DEVELOPING. LOWER CIGS THAT DID FORM HAVE SHIFTED EAST ACROSS INDIANA AND MICHIGAN WITH GENERALLY SKC ACROSS MUCH OF THE PLAINS/MIDWEST. OF CONCERN...HOWEVER IS RECENT OBSERVATIONS FROM DKB THAT SHOW LOWER VIS AND CIG. APPEARS TO BE LOCALIZED AS NO OTHER SITES CURRENTLY REPORTING ANYTHING THIS LOW AND SATELLITE IMAGES ALSO SHOW LITTLE COVERAGE. WILL NEED TO MONITOR OVER THE NEXT FEW HRS PUT PLAN TO REMOVE DRIZZLE AND BACK OFF TO JUST PATCHY FOG ACROSS THE NORTH THIS MORNING. TEMPERATURES CONTINUE TO SLOWLY RISE EARLY THIS MORNING WITH MOST AREAS IN THE 40S...STILL 30S OVER NORTH CENTRAL IL WITH 50S OVER A LARGE AREA OVER NORTHERN MO/SOUTHERN IA AND WESTERN IL. WITH SUN TODAY SEE LITTLE REASON WHY TEMPS WON/T MAKE IT INTO THE 50S WITH LOWER 50S NORTH TO MID 50S SOUTH...AND COULD BE TOO COOL ESPECIALLY SOUTHERN AREAS. A COLD FRONT MOVES SOUTHEAST ACROSS THE REGION THIS EVENING AND OVERNIGHT. LITTLE MOISTURE ASSOCIATED WITH THIS FRONT AND EXPECT JUST INCREASING CLOUDS THIS AFTERNOON/EVENING...THEN TURNING COLDER BY SUNDAY MORNING. HIGH PRESSURE BUILDS ACROSS THE WESTERN LAKES SUNDAY WHICH WILL BE DRY AND SUNNY. HIGHS SUNDAY A BIT TRICKY AS THE COLDER AIR BEGINS TO SHIFT EAST BY AFTERNOON AND MUCH OF THE SNOW PACK WILL BE GONE. HAVE ONLY NUDGED HIGHS UP BUT COULD STILL BE TOO COOL. WWA BEGINS SUNDAY NIGHT WITH LOWS POSSIBLY IN THE EVENING THEN SLOWLY RISING TEMPS OVERNIGHT. COULD BE SOME LIGHT SPRINKLES OR DEPENDING ON SFC TEMPS LIGHT FREEZING RAIN. PREVIOUS SLIGHT CHANCES HAVE BEEN REMOVED AND WILL MAINTAIN DRY FORECAST FOR NOW. WARM AIR SURGES BACK ACROSS THE AREA MONDAY AND THE MODELS HAVE BEEN FAIRLY CONSISTENT WITH A 4-8HR PERIOD OF SHOWERS/RAIN... PERHAPS ISOLATED TS MONDAY AFTERNOON INTO MONDAY EVENING. HAVE ATTEMPTED TO INTRODUCE SOME TIMING INTO THE GRIDS THIS MORNING BACKING OFF TO JUST CHANCE POPS MONDAY MORNING...KEEPING LIKELY MONDAY AFTERNOON/EVENING THEN GOING DRY ACROSS THE WESTERN CWA LATE MONDAY NIGHT AS IT APPEARS THE AREA WILL BE DRY SLOTTED AS THE SFC LOW LIFTS NORTHEAST ACROSS THE PLAINS. SOUTHWESTERLY FLOW LIKELY TO KEEP LOWS UP MONDAY NIGHT AND HAVE BUMPED TEMPS UP IN LINE WITH LATEST MEX. TUESDAY VERY WARM WITH HIGHS WELL INTO THE 50S AND PERHAPS EVEN SOME LOWER 60S SINCE THERE WILL LIKELY BE LITTLE SNOW LEFT ACROSS MUCH OF THE CWA. QPF AMOUNTS WITH PRECIP MONDAY AFTERNOON/MONDAY NIGHT APPEAR TO BE UNDER A HALF INCH AS THE HIGHER AMOUNTS EXPECTED TO FALL FURTHER SOUTH ACROSS CENTRAL IL AND CENTRAL INDIANA. SO WHILE THERE COULD BE SOME MINOR/LOCALIZED FLOODING...DOESN/T APPEAR RUNOFF FROM MELTING SNOW THIS WEEKEND COMBINED WITH RAINFALL MONDAY NIGHT WILL CAUSE ANY SIGNIFICANT RIVER RISES/FLOODING PROBLEMS. HOWEVER...MODELS CONTINUE TO BE IN FAIR AGREEMENT WITH THE NEXT SYSTEM THAT MOVES/DEVELOPS OVER THE AREA TUESDAY NIGHT INTO WEDNESDAY. NEW LOW PRESSURE DEVELOPS OVER THE SOUTHERN PLAINS AND LIFTS NORTHEAST ACROSS IL WEDNESDAY MORNING. GFS/ECMWF DIFFER ON THE DETAILS BUT BOTH SUPPORT A POTENTIAL HEAVY RAIN EVENT FOR THE AREA. WHILE TRENDS HAVE BEEN DECENT...TOO EARLY FOR ANY SPECIFICS BUT HAVE BUMPED POPS TO LIKELY LATE TUESDAY NIGHT INTO WEDNESDAY. SHOULD THE AREA RECEIVE HEAVY RAIN DURING THIS TIME...IT COULD LEAD TO RAPID RISES ON AREA RIVERS AND LIKELY CAUSE ICE JAM FLOODING. CMS && .AVIATION... 1200 UTC TAFS...AREA OF CONCERN FOR THE START OF THE FORECAST PERIOD WILL BE WINDS/WIND GUSTS ACROSS THE TERMINALS. ACARS SOUNDINGS THIS MORNING ARE SHOWING VERY STRONG WINDS JUST ABOVE THE SURFACE MOVING ACROSS THE CWA WITH UP TO 45 KNOTS AT AROUND 2K FT. ILX RADIOSONDE THIS MORNING INDICATED 47 KNOTS AT 1K FT AND 58 KNOTS AT 2K FT. WITH THESE WINDS JUST ABOVE THE SURFACE...HAVE INCLUDED LOW LEVEL WIND SHEAR TO START THE FORECAST PERIOD ACROSS THE TERMINALS AND INCLUDED THIS IN THE TAFS THROUGH 16Z TODAY. THESE STRONGER WINDS ALOFT WILL ALSO CONTINUE TO MIX DOWN TO THE SURFACE CREATING GUSTS INTO MID DAY. WITH STRONGER WINDS ALOFT EXITING AND AREA OF LOW PRESSURE ACROSS THE UPPER GREAT LAKES CONTINUING TO THE EAST...PRESSURE GRADIENT AT SURFACE WILL BECOME MORE RELAXED AND WIND GUSTS WILL DIMINISH DURING THE AFTERNOON. SKIES ACROSS THE TERMINALS WILL REMAIN CLEAR THROUGH MID MORNING UNTIL HIGH LEVEL CIRRUS IN THE SOUTHERN PLAINS MOVES NORTHEAST INTO THE CWA. AS NEXT WAVE OF ENERGY MOVES IN FROM THE NORTHWEST TONIGHT...CLOUD COVERAGE WILL BE ON THE INCREASE. ALTHOUGH CONFIDENCE IS NOT TO HIGH AT THIS POINT...HAVE INCLUDED A SCATTERED DECK OF 1500 FT AT 06Z TONIGHT BEFORE SKIES CLEAR ONCE AGAIN AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTH. RODRIGUEZ && .MARINE... 303 AM CST LOW PRESSURE OVER LAKE SUPERIOR WILL CONTINUE TO MOVE EAST ACROSS THE NORTHERN GREAT LAKES REGION ON SATURDAY. AS THIS SHIFTS EAST WINDS WILL INCREASE ACROSS THE LAKE THIS MORNING AS PRESSURE GRADIENT SLIDES EAST. THIS PRESSURE GRADIENT WILL PROVIDE WINDS JUST ABOVE 30 KNOTS AT TIMES BUT BELOW GALES BEFORE WINDS BEGIN TO DIMINISH THIS AFTERNOON AS THIS AREA OF LOW PRESSURE SHIFTS EAST. AS THIS OCCURS...IT WILL DRAG A COLD FRONT ACROSS THE LAKE AND SHIFT THE WINDS TO THE WEST THIS AFTERNOON AND NORTHWEST TONIGHT. HIGH PRESSURE THEN BUILDS INTO THE REGION ON SUNDAY AND CONTINUES TO SHIFT EAST MONDAY WHILE AN AREA OF LOW PRESSURE DEVELOPS ACROSS THE SOUTHERN PLAINS. THIS LOW WILL MOVE NORTH INTO THE NORTHERN PLAINS MONDAY NIGHT AND DRAG A WARM FRONT ACROSS THE LAKE WHICH WILL BEGIN TO INCREASE SOUTHERLY FLOW LATE MONDAY NIGHT. RODRIGUEZ && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741- LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872- LMZ874-LMZ876-LMZ878 UNTIL NOON SATURDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 PM SATURDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
604 AM CST SAT FEB 7 2009 .DISCUSSION... 330 AM...LITTLE IN THE WAY OF LOW CLOUDS/FOG AND DRIZZLE THIS MORNING. DESPITE WARM/MOIST AIR OVER SNOW...LOW LEVEL MIXING HAS LIKELY BEEN STRONG ENOUGH TO PREVENT LOW VIS/CIGS FROM DEVELOPING. LOWER CIGS THAT DID FORM HAVE SHIFTED EAST ACROSS INDIANA AND MICHIGAN WITH GENERALLY SKC ACROSS MUCH OF THE PLAINS/MIDWEST. OF CONCERN...HOWEVER IS RECENT OBSERVATIONS FROM DKB THAT SHOW LOWER VIS AND CIG. APPEARS TO BE LOCALIZED AS NO OTHER SITES CURRENTLY REPORTING ANYTHING THIS LOW AND SATELLITE IMAGES ALSO SHOW LITTLE COVERAGE. WILL NEED TO MONITOR OVER THE NEXT FEW HRS PUT PLAN TO REMOVE DRIZZLE AND BACK OFF TO JUST PATCHY FOG ACROSS THE NORTH THIS MORNING. TEMPERATURES CONTINUE TO SLOWLY RISE EARLY THIS MORNING WITH MOST AREAS IN THE 40S...STILL 30S OVER NORTH CENTRAL IL WITH 50S OVER A LARGE AREA OVER NORTHERN MO/SOUTHERN IA AND WESTERN IL. WITH SUN TODAY SEE LITTLE REASON WHY TEMPS WON/T MAKE IT INTO THE 50S WITH LOWER 50S NORTH TO MID 50S SOUTH...AND COULD BE TOO COOL ESPECIALLY SOUTHERN AREAS. A COLD FRONT MOVES SOUTHEAST ACROSS THE REGION THIS EVENING AND OVERNIGHT. LITTLE MOISTURE ASSOCIATED WITH THIS FRONT AND EXPECT JUST INCREASING CLOUDS THIS AFTERNOON/EVENING...THEN TURNING COLDER BY SUNDAY MORNING. HIGH PRESSURE BUILDS ACROSS THE WESTERN LAKES SUNDAY WHICH WILL BE DRY AND SUNNY. HIGHS SUNDAY A BIT TRICKY AS THE COLDER AIR BEGINS TO SHIFT EAST BY AFTERNOON AND MUCH OF THE SNOW PACK WILL BE GONE. HAVE ONLY NUDGED HIGHS UP BUT COULD STILL BE TOO COOL. WWA BEGINS SUNDAY NIGHT WITH LOWS POSSIBLY IN THE EVENING THEN SLOWLY RISING TEMPS OVERNIGHT. COULD BE SOME LIGHT SPRINKLES OR DEPENDING ON SFC TEMPS LIGHT FREEZING RAIN. PREVIOUS SLIGHT CHANCES HAVE BEEN REMOVED AND WILL MAINTAIN DRY FORECAST FOR NOW. WARM AIR SURGES BACK ACROSS THE AREA MONDAY AND THE MODELS HAVE BEEN FAIRLY CONSISTENT WITH A 4-8HR PERIOD OF SHOWERS/RAIN... PERHAPS ISOLATED TS MONDAY AFTERNOON INTO MONDAY EVENING. HAVE ATTEMPTED TO INTRODUCE SOME TIMING INTO THE GRIDS THIS MORNING BACKING OFF TO JUST CHANCE POPS MONDAY MORNING...KEEPING LIKELY MONDAY AFTERNOON/EVENING THEN GOING DRY ACROSS THE WESTERN CWA LATE MONDAY NIGHT AS IT APPEARS THE AREA WILL BE DRY SLOTTED AS THE SFC LOW LIFTS NORTHEAST ACROSS THE PLAINS. SOUTHWESTERLY FLOW LIKELY TO KEEP LOWS UP MONDAY NIGHT AND HAVE BUMPED TEMPS UP IN LINE WITH LATEST MEX. TUESDAY VERY WARM WITH HIGHS WELL INTO THE 50S AND PERHAPS EVEN SOME LOWER 60S SINCE THERE WILL LIKELY BE LITTLE SNOW LEFT ACROSS MUCH OF THE CWA. QPF AMOUNTS WITH PRECIP MONDAY AFTERNOON/MONDAY NIGHT APPEAR TO BE UNDER A HALF INCH AS THE HIGHER AMOUNTS EXPECTED TO FALL FURTHER SOUTH ACROSS CENTRAL IL AND CENTRAL INDIANA. SO WHILE THERE COULD BE SOME MINOR/LOCALIZED FLOODING...DOESN/T APPEAR RUNOFF FROM MELTING SNOW THIS WEEKEND COMBINED WITH RAINFALL MONDAY NIGHT WILL CAUSE ANY SIGNIFICANT RIVER RISES/FLOODING PROBLEMS. HOWEVER...MODELS CONTINUE TO BE IN FAIR AGREEMENT WITH THE NEXT SYSTEM THAT MOVES/DEVELOPS OVER THE AREA TUESDAY NIGHT INTO WEDNESDAY. NEW LOW PRESSURE DEVELOPS OVER THE SOUTHERN PLAINS AND LIFTS NORTHEAST ACROSS IL WEDNESDAY MORNING. GFS/ECMWF DIFFER ON THE DETAILS BUT BOTH SUPPORT A POTENTIAL HEAVY RAIN EVENT FOR THE AREA. WHILE TRENDS HAVE BEEN DECENT...TOO EARLY FOR ANY SPECIFICS BUT HAVE BUMPED POPS TO LIKELY LATE TUESDAY NIGHT INTO WEDNESDAY. SHOULD THE AREA RECEIVE HEAVY RAIN DURING THIS TIME...IT COULD LEAD TO RAPID RISES ON AREA RIVERS AND LIKELY CAUSE ICE JAM FLOODING. CMS && .AVIATION... 1200 UTC TAFS...AREA OF CONCERN FOR THE START OF THE FORECAST PERIOD WILL BE WINDS/WIND GUSTS ACROSS THE TERMINALS. ACARS SOUNDINGS THIS MORNING ARE SHOWING VERY STRONG WINDS JUST ABOVE THE SURFACE MOVING ACROSS THE CWA WITH UP TO 45 KNOTS AT AROUND 2K FT. ILX RADIOSONDE THIS MORNING INDICATED 47 KNOTS AT 1K FT AND 58 KNOTS AT 2K FT. WITH THESE WINDS JUST ABOVE THE SURFACE...HAVE INCLUDED LOW LEVEL WIND SHEAR TO START THE FORECAST PERIOD ACROSS THE TERMINALS AND INCLUDED THIS IN THE TAFS THROUGH 16Z TODAY. THESE STRONGER WINDS ALOFT WILL ALSO CONTINUE TO MIX DOWN TO THE SURFACE CREATING GUSTS INTO MID DAY. WITH STRONGER WINDS ALOFT EXITING AND AREA OF LOW PRESSURE ACROSS THE UPPER GREAT LAKES CONTINUING TO THE EAST...PRESSURE GRADIENT AT SURFACE WILL BECOME MORE RELAXED AND WIND GUSTS WILL DIMINISH DURING THE AFTERNOON. SKIES ACROSS THE TERMINALS WILL REMAIN CLEAR THROUGH MID MORNING UNTIL HIGH LEVEL CIRRUS IN THE SOUTHERN PLAINS MOVES NORTHEAST INTO THE CWA. AS NEXT WAVE OF ENERGY MOVES IN FROM THE NORTHWEST TONIGHT...CLOUD COVERAGE WILL BE ON THE INCREASE. ALTHOUGH CONFIDENCE IS NOT TO HIGH AT THIS POINT...HAVE INCLUDED A SCATTERED DECK OF 1500 FT AT 06Z TONIGHT BEFORE SKIES CLEAR ONCE AGAIN AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTH. RODRIGUEZ && .MARINE... 303 AM CST LOW PRESSURE OVER LAKE SUPERIOR WILL CONTINUE TO MOVE EAST ACROSS THE NORTHERN GREAT LAKES REGION ON SATURDAY. AS THIS SHIFTS EAST WINDS WILL INCREASE ACROSS THE LAKE THIS MORNING AS PRESSURE GRADIENT SLIDES EAST. THIS PRESSURE GRADIENT WILL PROVIDE WINDS JUST ABOVE 30 KNOTS AT TIMES BUT BELOW GALES BEFORE WINDS BEGIN TO DIMINISH THIS AFTERNOON AS THIS AREA OF LOW PRESSURE SHIFTS EAST. AS THIS OCCURS...IT WILL DRAG A COLD FRONT ACROSS THE LAKE AND SHIFT THE WINDS TO THE WEST THIS AFTERNOON AND NORTHWEST TONIGHT. HIGH PRESSURE THEN BUILDS INTO THE REGION ON SUNDAY AND CONTINUES TO SHIFT EAST MONDAY WHILE AN AREA OF LOW PRESSURE DEVELOPS ACROSS THE SOUTHERN PLAINS. THIS LOW WILL MOVE NORTH INTO THE NORTHERN PLAINS MONDAY NIGHT AND DRAG A WARM FRONT ACROSS THE LAKE WHICH WILL BEGIN TO INCREASE SOUTHERLY FLOW LATE MONDAY NIGHT. RODRIGUEZ && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741- LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872- LMZ874-LMZ876-LMZ878 UNTIL NOON SATURDAY. SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...NOON SATURDAY TO 4 PM SATURDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
330 AM CST SAT FEB 7 2009 .DISCUSSION... 330 AM...LITTLE IN THE WAY OF LOW CLOUDS/FOG AND DRIZZLE THIS MORNING. DESPITE WARM/MOIST AIR OVER SNOW...LOW LEVEL MIXING HAS LIKELY BEEN STRONG ENOUGH TO PREVENT LOW VIS/CIGS FROM DEVELOPING. LOWER CIGS THAT DID FORM HAVE SHIFTED EAST ACROSS INDIANA AND MICHIGAN WITH GENERALLY SKC ACROSS MUCH OF THE PLAINS/MIDWEST. OF CONCERN...HOWEVER IS RECENT OBSERVATIONS FROM DKB THAT SHOW LOWER VIS AND CIG. APPEARS TO BE LOCALIZED AS NO OTHER SITES CURRENTLY REPORTING ANYTHING THIS LOW AND SATELLITE IMAGES ALSO SHOW LITTLE COVERAGE. WILL NEED TO MONITOR OVER THE NEXT FEW HRS PUT PLAN TO REMOVE DRIZZLE AND BACK OFF TO JUST PATCHY FOG ACROSS THE NORTH THIS MORNING. TEMPERATURES CONTINUE TO SLOWLY RISE EARLY THIS MORNING WITH MOST AREAS IN THE 40S...STILL 30S OVER NORTH CENTRAL IL WITH 50S OVER A LARGE AREA OVER NORTHERN MO/SOUTHERN IA AND WESTERN IL. WITH SUN TODAY SEE LITTLE REASON WHY TEMPS WON/T MAKE IT INTO THE 50S WITH LOWER 50S NORTH TO MID 50S SOUTH...AND COULD BE TOO COOL ESPECIALLY SOUTHERN AREAS. A COLD FRONT MOVES SOUTHEAST ACROSS THE REGION THIS EVENING AND OVERNIGHT. LITTLE MOISTURE ASSOCIATED WITH THIS FRONT AND EXPECT JUST INCREASING CLOUDS THIS AFTERNOON/EVENING...THEN TURNING COLDER BY SUNDAY MORNING. HIGH PRESSURE BUILDS ACROSS THE WESTERN LAKES SUNDAY WHICH WILL BE DRY AND SUNNY. HIGHS SUNDAY A BIT TRICKY AS THE COLDER AIR BEGINS TO SHIFT EAST BY AFTERNOON AND MUCH OF THE SNOW PACK WILL BE GONE. HAVE ONLY NUDGED HIGHS UP BUT COULD STILL BE TOO COOL. WWA BEGINS SUNDAY NIGHT WITH LOWS POSSIBLY IN THE EVENING THEN SLOWLY RISING TEMPS OVERNIGHT. COULD BE SOME LIGHT SPRINKLES OR DEPENDING ON SFC TEMPS LIGHT FREEZING RAIN. PREVIOUS SLIGHT CHANCES HAVE BEEN REMOVED AND WILL MAINTAIN DRY FORECAST FOR NOW. WARM AIR SURGES BACK ACROSS THE AREA MONDAY AND THE MODELS HAVE BEEN FAIRLY CONSISTENT WITH A 4-8HR PERIOD OF SHOWERS/RAIN... PERHAPS ISOLATED TS MONDAY AFTERNOON INTO MONDAY EVENING. HAVE ATTEMPTED TO INTRODUCE SOME TIMING INTO THE GRIDS THIS MORNING BACKING OFF TO JUST CHANCE POPS MONDAY MORNING...KEEPING LIKELY MONDAY AFTERNOON/EVENING THEN GOING DRY ACROSS THE WESTERN CWA LATE MONDAY NIGHT AS IT APPEARS THE AREA WILL BE DRY SLOTTED AS THE SFC LOW LIFTS NORTHEAST ACROSS THE PLAINS. SOUTHWESTERLY FLOW LIKELY TO KEEP LOWS UP MONDAY NIGHT AND HAVE BUMPED TEMPS UP IN LINE WITH LATEST MEX. TUESDAY VERY WARM WITH HIGHS WELL INTO THE 50S AND PERHAPS EVEN SOME LOWER 60S SINCE THERE WILL LIKELY BE LITTLE SNOW LEFT ACROSS MUCH OF THE CWA. QPF AMOUNTS WITH PRECIP MONDAY AFTERNOON/MONDAY NIGHT APPEAR TO BE UNDER A HALF INCH AS THE HIGHER AMOUNTS EXPECTED TO FALL FURTHER SOUTH ACROSS CENTRAL IL AND CENTRAL INDIANA. SO WHILE THERE COULD BE SOME MINOR/LOCALIZED FLOODING...DOESN/T APPEAR RUNOFF FROM MELTING SNOW THIS WEEKEND COMBINED WITH RAINFALL MONDAY NIGHT WILL CAUSE ANY SIGNIFICANT RIVER RISES/FLOODING PROBLEMS. HOWEVER...MODELS CONTINUE TO BE IN FAIR AGREEMENT WITH THE NEXT SYSTEM THAT MOVES/DEVELOPS OVER THE AREA TUESDAY NIGHT INTO WEDNESDAY. NEW LOW PRESSURE DEVELOPS OVER THE SOUTHERN PLAINS AND LIFTS NORTHEAST ACROSS IL WEDNESDAY MORNING. GFS/ECMWF DIFFER ON THE DETAILS BUT BOTH SUPPORT A POTENTIAL HEAVY RAIN EVENT FOR THE AREA. WHILE TRENDS HAVE BEEN DECENT...TOO EARLY FOR ANY SPECIFICS BUT HAVE BUMPED POPS TO LIKELY LATE TUESDAY NIGHT INTO WEDNESDAY. SHOULD THE AREA RECEIVE HEAVY RAIN DURING THIS TIME...IT COULD LEAD TO RAPID RISES ON AREA RIVERS AND LIKELY CAUSE ICE JAM FLOODING. CMS && .AVIATION... 1045 PM CST 0600 UTC TAFS...MAIN FORECAST ISSUE CONTINUES TO CENTER ON POTENTIAL OF LOWER CIGS/VSBYS TONIGHT INTO SATURDAY. BOUNDARY WHICH HAS BEEN STALLED ACROSS SOUTHEAST IOWA INTO CENTRAL ILLINOIS FINALLY APPEARS TO BE SURGING NORTHWARD LATE THIS EVENING AS FAIRLY STRONG SFC PRESSURE FALLS HAVE MOVED ACROSS THE UPPER GREAT LAKES IN ADVANCE OF LOW PRESSURE ACROSS MINNESOTA. ENHANCED LOW LEVEL MOISTURE ADVECTION WITH THE APPROACHING FRONT HAS LED TO RECENT DEVELOPMENT OF MVFR CIGS FROM 1000-1500 FT FROM CENTRAL ILLINOIS EXTENDING INTO FAR NORTHWEST INDIANA. EXPECTING ADDITIONAL DEVELOPMENT OF THIS STRATUS BACK TO THE NORTHWEST ACROSS THE REMAINDER OF NORTH CENTRAL ILLINOIS OVER THE NEXT SEVERAL HOURS...AND NOT PLANNING ON MAKING SIGNIFICANT CHANGES TO TIMING IFR CIGS ACROSS TERMINALS...PERHAPS JUST PUSHED A FEW HOURS BACK FROM THE PREVIOUS TAFS...MORE TOWARD 07Z-08Z. CONFIDENCE IS RATHER LOW CONCERNING EXACT TIMING OF THE IFR OR LOW END MVFR CIGS ACROSS RFD/DPA BUT GIVEN TRENDS WITH MORE SIGNIFICANT MOISTURE ADVECTION LIFTING NORTHWARD WITH THE WARM FRONT AND CONTINUED SNOWMELT...STILL BELIEVE THAT THESE CIGS HAVE A GOOD CHANCE OF DEVELOPING OVER THE NEXT FEW HOURS. WILL CARRY IFR CIGS/VSBYS THROUGH THE MORNING HOURS TOMORROW...AND TREND TO LOW MVFR CIGS/VSBYS OF 3SM/1000 FT EARLY SATURDAY AFTERNOON. STILL SOME UNCERTAINTIES REMAIN WITH REGARDS TO HOW CONTINUED SNOWMELT ON SATURDAY WILL AFFECT CIG/VSBY TRENDS HOWEVER. WILL MAINTAIN MENTION OF MVFR CIGS THROUGH EARLY EVENING TOMORROW WITH COLD ADVECTION BEHIND THE FRONT...BUT BY LATE EVENING INTO THE OVERNIGHT EXPECTING LOW CLOUDS TO SCATTER AS DRIER LOW LEVEL AIR BUILDS INTO THE AREA. IN TERMS OF WINDS...SOUTH WINDS GUSTING TO 20 TO 25 KNOTS WILL CONTINUE THROUGH THE NIGHT BEFORE VEERING SOUTHWEST ON SATURDAY WITH CONTINUED GUSTS TO 20 KNOTS IN THE AFTERNOON. NORTHWEST WINDS ARE THEN EXPECTED BY SATURDAY EVENING BEHIND THE FRONT AND WILL CONTINUE THROUGH SATURDAY NIGHT. OTHER CONCERN THIS EVENING WITH 45 TO 50 KNOT WINDS BETWEEN 1500-2000 FT HAS BEEN ON POTENTIAL OF LLWS BUT LATEST ACARS SOUNDINGS SUGGEST LLWS CRITERIA NOT BEING MET. MARSILI && .MARINE... 303 AM CST LOW PRESSURE OVER LAKE SUPERIOR WILL CONTINUE TO MOVE EAST ACROSS THE NORTHERN GREAT LAKES REGION ON SATURDAY. AS THIS SHIFTS EAST WINDS WILL INCREASE ACROSS THE LAKE THIS MORNING AS PRESSURE GRADIENT SLIDES EAST. THIS PRESSURE GRADIENT WILL PROVIDE WINDS JUST ABOVE 30 KNOTS AT TIMES BUT BELOW GALES BEFORE WINDS BEGIN TO DIMINISH THIS AFTERNOON AS THIS AREA OF LOW PRESSURE SHIFTS EAST. AS THIS OCCURS...IT WILL DRAG A COLD FRONT ACROSS THE LAKE AND SHIFT THE WINDS TO THE WEST THIS AFTERNOON AND NORTHWEST TONIGHT. HIGH PRESSURE THEN BUILDS INTO THE REGION ON SUNDAY AND CONTINUES TO SHIFT EAST MONDAY WHILE AN AREA OF LOW PRESSURE DEVELOPS ACROSS THE SOUTHERN PLAINS. THIS LOW WILL MOVE NORTH INTO THE NORTHERN PLAINS MONDAY NIGHT AND DRAG A WARM FRONT ACROSS THE LAKE WHICH WILL BEGIN TO INCREASE SOUTHERLY FLOW LATE MONDAY NIGHT. RODRIGUEZ && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 PM SATURDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
314 AM CST SAT FEB 7 2009 .DISCUSSION... MAJOR WARMING UNDER WAY AS WARM...MOIST AIR SURGES NORTHWARD UP THE MISSISSIPPI VALLEY AND INTO THE UPPER MIDWEST. SKIES HAVE REMAINED MOSTLY SUNNY TODAY...ALLOWING MAXIMUM INSOLATION TO COMBINE WITH THE WARM AIR...ALLOWING TEMPERATURES TO ALREADY REACH INTO THE 50S OVER THE SWRN PORTIONS OF THE CWA. BASED ON LATEST OBSERVATIONAL TRENDS...EXPECT THAT THE LOW CIGS/FOG/DZ WILL LIKELY BE DELAYED UNTIL MIDNIGHT OR AFTER...AND TEMPERATURES WILL CONTINUE TO CLIMB THROUGH THE EVENING WITH LITTLE DIURNAL COOLING OCCURRING OVERNIGHT. THE SHORT TERM MODELS STILL WANT TO DEVELOP A WELL SATURATED LAYER BELOW 900MB-850MB BELOW A VERY DRY LAYER ALOFT...INDICATING THE LIKELIHOOD OF LOW STRATUS...DRIZZLE AND FOG...BUT GIVEN THE FACT THAT ANY LOW CIGS/VIS ARE STILL WELL TO THE SOUTHWEST...HAVE BACKED OFF ON POPS TO BELOW THE MAGIC 14 PERCENT AND WILL ONLY MENTION AREAS FOG/PATCHY DRIZZLE. AT THIS POINT...THE CHANCES FOR ANY KIND OF WETTING RAIN TONIGHT AND TOMORROW ARE MINIMAL. ANOTHER INDICATOR POINTING AGAINST REALLY FOGGY/DRIZZLY CONDITIONS ARE SEEN BY CLOSELY LOOKING AT SFC BASED AND 850MB PARCEL TRAJECTORIES. FOR THIS EVENING AND TONIGHT...THE SOURCE REGION OF AIR ADVECTION OVER THE LOCAL AREA COMES FROM OLD MEXICO/CNTRL TEXAS. THE GREATER MOISTURE ADVECTION WITH GULF OF MEXICO SOURCED AIR LOOKS TO BE SHUNTED SOUTH AND EAST OF THE LOCAL AREA...MORE OVER CENTRAL ILLINOIS AND SRN INDIANA. SO...WHILE NOT READY TO COMPLETELY MINIMIZE THE POTENTIAL FOR FOG/DRIZZLE...WILL TREND TO MINIMIZING THE IMPACT. STILL EXPECT TO SEE ALL OF THE SNOWPACK TO MELT TONIGHT AND TOMORROW. IN THE ABSENCE OF ANY QPF...THE AMOUNT OF RUNOFF WILL BE A BIT LESS THAN EXPECTED...SO SEE LESS OF A CHANCE FOR RIVER FLOODING DUE TO RUNOFF. HOWEVER...ICE JAM FLOODING WILL STILL BE A SIGNIFICANT CONCERN OVER THE WEEKEND. WITH TEMPERATURES RISING INTO THE 40S AND 50S TODAY AND 50S TOMORROW...INCREASED STREAMFLOW FROM THE SNOW MELT WILL LIKELY HASTEN THE BREAKUP OF ICE ON AREA RIVERS. LOCATIONS PRONE TO ICE JAM FLOODING WILL STILL NEED TO BE CLOSELY MONITORED FOR POSSIBLE FLASH FLOOD WARNINGS. THE GUIDANCE REMAINS CONSISTENT IN BRINGING A CLIPPER THROUGH THE GREAT LAKES REGION SATURDAY WITH AN ASSOCIATED COLD FRONT SWEEPING ACROSS THE CWA SATURDAY NIGHT. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT...LEADING TO A BRIEF BREAK IN THE WARMING TREND..BUT TEMPERATURES WILL STILL BE WELL ABOVE NORMAL. IN THE WAKE OF THIS HIGH PRESSURE...A SERIES OF STRONG SHORT WAVES ARE EXPECTED TO EJECT OUT OF THE SOUTHERN ROCKIES IN STRONG SOUTHERN STREAM FLOW. THE GFS IS TRENDING A BIT FARTHER NORTH THAN THE ECMWF WITH THE FIRST OF THESE WAVES ON MONDAY AND TUESDAY...THOUGH THE IMPACT ON THE LOCAL WEATHER WILL BE MINIMAL. REGARDLESS OF WHICH SOLUTION VERIFIES BETTER...EXPECT TEMPERATURES TO RISE BACK INTO THE 50S...AND WITH A BETTER MOISTURE INFLUX THAN WILL BE SEEN THIS WEEKEND...THE CHANCE FOR SIGNIFICANT RAINFALL...AND EVEN SOME THUNDERSTORMS IS MUCH GREATER. DIFFERENCES IN THE TRACK OF THE SECOND WAVE ARE MORE SIGNIFICANT WITH THE GFS TRACKING THE SFC LOW CENTER OVER GARY WHILE THE ECMWF TRACKS THE LOW CENTER SOUTH OF INDIANAPOLIS. THIS COULD BE THE DIFFERENCE BETWEEN COLD RAIN OR SIGNIFICANT SNOW. GIVEN THAT WE`RE STILL TALKING ABOUT THE LATTER PORTIONS OF THE EXTENDED FORECAST PERIOD...WEDNESDAY NIGHT AND THURSDAY...WILL NOT GET TOO EXCITED ABOUT LATCHING ON TO ONE SOLUTION JUST YET. HOWEVER...THE ECMWF HAS HAD A BETTER TRACK RECORD THIS WINTER...SO DESPITE A SIGNIFICANT WARMING TREND DURING THE SHORT TERM...THERE IS STILL A LOT OF WINTER LEFT FOR NORTHERN ILLINOIS AND NORTHWESTERN INDIANA. KREIN && .AVIATION... 1045 PM CST 0600 UTC TAFS...MAIN FORECAST ISSUE CONTINUES TO CENTER ON POTENTIAL OF LOWER CIGS/VSBYS TONIGHT INTO SATURDAY. BOUNDARY WHICH HAS BEEN STALLED ACROSS SOUTHEAST IOWA INTO CENTRAL ILLINOIS FINALLY APPEARS TO BE SURGING NORTHWARD LATE THIS EVENING AS FAIRLY STRONG SFC PRESSURE FALLS HAVE MOVED ACROSS THE UPPER GREAT LAKES IN ADVANCE OF LOW PRESSURE ACROSS MINNESOTA. ENHANCED LOW LEVEL MOISTURE ADVECTION WITH THE APPROACHING FRONT HAS LED TO RECENT DEVELOPMENT OF MVFR CIGS FROM 1000-1500 FT FROM CENTRAL ILLINOIS EXTENDING INTO FAR NORTHWEST INDIANA. EXPECTING ADDITIONAL DEVELOPMENT OF THIS STRATUS BACK TO THE NORTHWEST ACROSS THE REMAINDER OF NORTH CENTRAL ILLINOIS OVER THE NEXT SEVERAL HOURS...AND NOT PLANNING ON MAKING SIGNIFICANT CHANGES TO TIMING IFR CIGS ACROSS TERMINALS...PERHAPS JUST PUSHED A FEW HOURS BACK FROM THE PREVIOUS TAFS...MORE TOWARD 07Z-08Z. CONFIDENCE IS RATHER LOW CONCERNING EXACT TIMING OF THE IFR OR LOW END MVFR CIGS ACROSS RFD/DPA BUT GIVEN TRENDS WITH MORE SIGNIFICANT MOISTURE ADVECTION LIFTING NORTHWARD WITH THE WARM FRONT AND CONTINUED SNOWMELT...STILL BELIEVE THAT THESE CIGS HAVE A GOOD CHANCE OF DEVELOPING OVER THE NEXT FEW HOURS. WILL CARRY IFR CIGS/VSBYS THROUGH THE MORNING HOURS TOMORROW...AND TREND TO LOW MVFR CIGS/VSBYS OF 3SM/1000 FT EARLY SATURDAY AFTERNOON. STILL SOME UNCERTAINTIES REMAIN WITH REGARDS TO HOW CONTINUED SNOWMELT ON SATURDAY WILL AFFECT CIG/VSBY TRENDS HOWEVER. WILL MAINTAIN MENTION OF MVFR CIGS THROUGH EARLY EVENING TOMORROW WITH COLD ADVECTION BEHIND THE FRONT...BUT BY LATE EVENING INTO THE OVERNIGHT EXPECTING LOW CLOUDS TO SCATTER AS DRIER LOW LEVEL AIR BUILDS INTO THE AREA. IN TERMS OF WINDS...SOUTH WINDS GUSTING TO 20 TO 25 KNOTS WILL CONTINUE THROUGH THE NIGHT BEFORE VEERING SOUTHWEST ON SATURDAY WITH CONTINUED GUSTS TO 20 KNOTS IN THE AFTERNOON. NORTHWEST WINDS ARE THEN EXPECTED BY SATURDAY EVENING BEHIND THE FRONT AND WILL CONTINUE THROUGH SATURDAY NIGHT. OTHER CONCERN THIS EVENING WITH 45 TO 50 KNOT WINDS BETWEEN 1500-2000 FT HAS BEEN ON POTENTIAL OF LLWS BUT LATEST ACARS SOUNDINGS SUGGEST LLWS CRITERIA NOT BEING MET. MARSILI && .MARINE... 303 AM CST LOW PRESSURE OVER LAKE SUPERIOR WILL CONTINUE TO MOVE EAST ACROSS THE NORTHERN GREAT LAKES REGION ON SATURDAY. AS THIS SHIFTS EAST WINDS WILL INCREASE ACROSS THE LAKE THIS MORNING AS PRESSURE GRADIENT SLIDES EAST. THIS PRESSURE GRADIENT WILL PROVIDE WINDS JUST ABOVE 30 KNOTS AT TIMES BUT BELOW GALES BEFORE WINDS BEGIN TO DIMINISH THIS AFTERNOON AS THIS AREA OF LOW PRESSURE SHIFTS EAST. AS THIS OCCURS...IT WILL DRAG A COLD FRONT ACROSS THE LAKE AND SHIFT THE WINDS TO THE WEST THIS AFTERNOON AND NORTHWEST TONIGHT. HIGH PRESSURE THEN BUILDS INTO THE REGION ON SUNDAY AND CONTINUES TO SHIFT EAST MONDAY WHILE AN AREA OF LOW PRESSURE DEVELOPS ACROSS THE SOUTHERN PLAINS. THIS LOW WILL MOVE NORTH INTO THE NORTHERN PLAINS MONDAY NIGHT AND DRAG A WARM FRONT ACROSS THE LAKE WHICH WILL BEGIN TO INCREASE SOUTHERLY FLOW LATE MONDAY NIGHT. RODRIGUEZ && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 PM SATURDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1050 PM CST FRI FEB 6 2009 .DISCUSSION... MAJOR WARMING UNDER WAY AS WARM...MOIST AIR SURGES NORTHWARD UP THE MISSISSIPPI VALLEY AND INTO THE UPPER MIDWEST. SKIES HAVE REMAINED MOSTLY SUNNY TODAY...ALLOWING MAXIMUM INSOLATION TO COMBINE WITH THE WARM AIR...ALLOWING TEMPERATURES TO ALREADY REACH INTO THE 50S OVER THE SWRN PORTIONS OF THE CWA. BASED ON LATEST OBSERVATIONAL TRENDS...EXPECT THAT THE LOW CIGS/FOG/DZ WILL LIKELY BE DELAYED UNTIL MIDNIGHT OR AFTER...AND TEMPERATURES WILL CONTINUE TO CLIMB THROUGH THE EVENING WITH LITTLE DIURNAL COOLING OCCURRING OVERNIGHT. THE SHORT TERM MODELS STILL WANT TO DEVELOP A WELL SATURATED LAYER BELOW 900MB-850MB BELOW A VERY DRY LAYER ALOFT...INDICATING THE LIKELIHOOD OF LOW STRATUS...DRIZZLE AND FOG...BUT GIVEN THE FACT THAT ANY LOW CIGS/VIS ARE STILL WELL TO THE SOUTHWEST...HAVE BACKED OFF ON POPS TO BELOW THE MAGIC 14 PERCENT AND WILL ONLY MENTION AREAS FOG/PATCHY DRIZZLE. AT THIS POINT...THE CHANCES FOR ANY KIND OF WETTING RAIN TONIGHT AND TOMORROW ARE MINIMAL. ANOTHER INDICATOR POINTING AGAINST REALLY FOGGY/DRIZZLY CONDITIONS ARE SEEN BY CLOSELY LOOKING AT SFC BASED AND 850MB PARCEL TRAJECTORIES. FOR THIS EVENING AND TONIGHT...THE SOURCE REGION OF AIR ADVECTION OVER THE LOCAL AREA COMES FROM OLD MEXICO/CNTRL TEXAS. THE GREATER MOISTURE ADVECTION WITH GULF OF MEXICO SOURCED AIR LOOKS TO BE SHUNTED SOUTH AND EAST OF THE LOCAL AREA...MORE OVER CENTRAL ILLINOIS AND SRN INDIANA. SO...WHILE NOT READY TO COMPLETELY MINIMIZE THE POTENTIAL FOR FOG/DRIZZLE...WILL TREND TO MINIMIZING THE IMPACT. STILL EXPECT TO SEE ALL OF THE SNOWPACK TO MELT TONIGHT AND TOMORROW. IN THE ABSENCE OF ANY QPF...THE AMOUNT OF RUNOFF WILL BE A BIT LESS THAN EXPECTED...SO SEE LESS OF A CHANCE FOR RIVER FLOODING DUE TO RUNOFF. HOWEVER...ICE JAM FLOODING WILL STILL BE A SIGNIFICANT CONCERN OVER THE WEEKEND. WITH TEMPERATURES RISING INTO THE 40S AND 50S TODAY AND 50S TOMORROW...INCREASED STREAMFLOW FROM THE SNOW MELT WILL LIKELY HASTEN THE BREAKUP OF ICE ON AREA RIVERS. LOCATIONS PRONE TO ICE JAM FLOODING WILL STILL NEED TO BE CLOSELY MONITORED FOR POSSIBLE FLASH FLOOD WARNINGS. THE GUIDANCE REMAINS CONSISTENT IN BRINGING A CLIPPER THROUGH THE GREAT LAKES REGION SATURDAY WITH AN ASSOCIATED COLD FRONT SWEEPING ACROSS THE CWA SATURDAY NIGHT. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT...LEADING TO A BRIEF BREAK IN THE WARMING TREND..BUT TEMPERATURES WILL STILL BE WELL ABOVE NORMAL. IN THE WAKE OF THIS HIGH PRESSURE...A SERIES OF STRONG SHORT WAVES ARE EXPECTED TO EJECT OUT OF THE SOUTHERN ROCKIES IN STRONG SOUTHERN STREAM FLOW. THE GFS IS TRENDING A BIT FARTHER NORTH THAN THE ECMWF WITH THE FIRST OF THESE WAVES ON MONDAY AND TUESDAY...THOUGH THE IMPACT ON THE LOCAL WEATHER WILL BE MINIMAL. REGARDLESS OF WHICH SOLUTION VERIFIES BETTER...EXPECT TEMPERATURES TO RISE BACK INTO THE 50S...AND WITH A BETTER MOISTURE INFLUX THAN WILL BE SEEN THIS WEEKEND...THE CHANCE FOR SIGNIFICANT RAINFALL...AND EVEN SOME THUNDERSTORMS IS MUCH GREATER. DIFFERENCES IN THE TRACK OF THE SECOND WAVE ARE MORE SIGNIFICANT WITH THE GFS TRACKING THE SFC LOW CENTER OVER GARY WHILE THE ECMWF TRACKS THE LOW CENTER SOUTH OF INDIANAPOLIS. THIS COULD BE THE DIFFERENCE BETWEEN COLD RAIN OR SIGNIFICANT SNOW. GIVEN THAT WE`RE STILL TALKING ABOUT THE LATTER PORTIONS OF THE EXTENDED FORECAST PERIOD...WEDNESDAY NIGHT AND THURSDAY...WILL NOT GET TOO EXCITED ABOUT LATCHING ON TO ONE SOLUTION JUST YET. HOWEVER...THE ECMWF HAS HAD A BETTER TRACK RECORD THIS WINTER...SO DESPITE A SIGNIFICANT WARMING TREND DURING THE SHORT TERM...THERE IS STILL A LOT OF WINTER LEFT FOR NORTHERN ILLINOIS AND NORTHWESTERN INDIANA. KREIN && .AVIATION... 1045 PM CST 0600 UTC TAFS...MAIN FORECAST ISSUE CONTINUES TO CENTER ON POTENTIAL OF LOWER CIGS/VSBYS TONIGHT INTO SATURDAY. BOUNDARY WHICH HAS BEEN STALLED ACROSS SOUTHEAST IOWA INTO CENTRAL ILLINOIS FINALLY APPEARS TO BE SURGING NORTHWARD LATE THIS EVENING AS FAIRLY STRONG SFC PRESSURE FALLS HAVE MOVED ACROSS THE UPPER GREAT LAKES IN ADVANCE OF LOW PRESSURE ACROSS MINNESOTA. ENHANCED LOW LEVEL MOISTURE ADVECTION WITH THE APPROACHING FRONT HAS LED TO RECENT DEVELOPMENT OF MVFR CIGS FROM 1000-1500 FT FROM CENTRAL ILLINOIS EXTENDING INTO FAR NORTHWEST INDIANA. EXPECTING ADDITIONAL DEVELOPMENT OF THIS STRATUS BACK TO THE NORTHWEST ACROSS THE REMAINDER OF NORTH CENTRAL ILLINOIS OVER THE NEXT SEVERAL HOURS...AND NOT PLANNING ON MAKING SIGNIFICANT CHANGES TO TIMING IFR CIGS ACROSS TERMINALS...PERHAPS JUST PUSHED A FEW HOURS BACK FROM THE PREVIOUS TAFS...MORE TOWARD 07Z-08Z. CONFIDENCE IS RATHER LOW CONCERNING EXACT TIMING OF THE IFR OR LOW END MVFR CIGS ACROSS RFD/DPA BUT GIVEN TRENDS WITH MORE SIGNIFICANT MOISTURE ADVECTION LIFTING NORTHWARD WITH THE WARM FRONT AND CONTINUED SNOWMELT...STILL BELIEVE THAT THESE CIGS HAVE A GOOD CHANCE OF DEVELOPING OVER THE NEXT FEW HOURS. WILL CARRY IFR CIGS/VSBYS THROUGH THE MORNING HOURS TOMORROW...AND TREND TO LOW MVFR CIGS/VSBYS OF 3SM/1000 FT EARLY SATURDAY AFTERNOON. STILL SOME UNCERTAINTIES REMAIN WITH REGARDS TO HOW CONTINUED SNOWMELT ON SATURDAY WILL AFFECT CIG/VSBY TRENDS HOWEVER. WILL MAINTAIN MENTION OF MVFR CIGS THROUGH EARLY EVENING TOMORROW WITH COLD ADVECTION BEHIND THE FRONT...BUT BY LATE EVENING INTO THE OVERNIGHT EXPECTING LOW CLOUDS TO SCATTER AS DRIER LOW LEVEL AIR BUILDS INTO THE AREA. IN TERMS OF WINDS...SOUTH WINDS GUSTING TO 20 TO 25 KNOTS WILL CONTINUE THROUGH THE NIGHT BEFORE VEERING SOUTHWEST ON SATURDAY WITH CONTINUED GUSTS TO 20 KNOTS IN THE AFTERNOON. NORTHWEST WINDS ARE THEN EXPECTED BY SATURDAY EVENING BEHIND THE FRONT AND WILL CONTINUE THROUGH SATURDAY NIGHT. OTHER CONCERN THIS EVENING WITH 45 TO 50 KNOT WINDS BETWEEN 1500-2000 FT HAS BEEN ON POTENTIAL OF LLWS BUT LATEST ACARS SOUNDINGS SUGGEST LLWS CRITERIA NOT BEING MET. MARSILI && .MARINE... 305 PM CST LOW PRESSURE OVER THE CENTRAL PLAINS WILL MOVE NORTHEAST OVER LAKE SUPERIOR BY SATURDAY MORNING...WITH A WARM FRONT LIFTING OVER LAKE MICHIGAN OVERNIGHT TONIGHT. WINDS WILL BE SOUTH AND INCREASE AS THE GRADIENT TIGHTENS IN ASSOCIATION WITH THIS LOW. MODEL FORECAST SOUNDINGS INDICATE WINDS AROUND 30 KNOTS LATER TONIGHT AND SATURDAY...PERHAPS MARGINALLY TOUCHING GALE FORCE FOR A BRIEF TIME EARLY SATURDAY MORNING. GIVEN STRENGTH OF INVERSION AND MINIMAL DURATION OF POTENTIAL GALES WILL NOT ISSUED GALE WARNING AND WILL MAINTAIN FORECAST AT 30 KNOTS. LOW MOVES NORTHEAST INTO QUEBEC SATURDAY NIGHT WITH TRAILING COLD FRONT MOVING ACROSS THE LAKE BY EVENING. WINDS SHIFT NORTHWEST AND DECREASE OVERNIGHT AS HIGH PRESSURE BUILDS FROM PLAINS TO THE LAKES AND OHIO VALLEY ON SUNDAY. ANOTHER LOW DEVELOPS MONDAY/TUESDAY ACROSS THE PLAINS...MOVING NORTH/NORTHEAST THROUGH THE UPPER MIDWEST. THIS WILL LIKELY RESULT IN ANOTHER BOUT OF INCREASING SOUTH/SOUTHEAST WINDS DURING THIS TIME PERIOD. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 PM SATURDAY. && $$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
826 AM EST SAT FEB 7 2009 .UPDATE... FAIRLY SIGNIFICANT NEAR TERM UPDATES PER SATELLITE AND OBSERVATIONAL DATA TRENDS. RUC 850RH PRETTY COINCIDENT WITH BACK EDGE OF CLOUDS THIS MORNING AND TRENDED LOWER WITH SKY COVER TODAY PER PROGS. LEANED HEAVILY TOWARD WARMER LAV #S FOR HIGHS AS CLEARING THROUGH AT LEAST THIS MORNING SHOULD ALLOW BETTER MIXING THAN ONCE THOUGHT. EXPECT HIGHS TO PUSH INTO AT LEAST THE MID 50S SW PORTION OF CWA WITH SCT TO BKN CU OR SC TO LIKELY DEVELOP INTO THE AFTERNOON. REMOVED DRIZZLE AS LACK OF MOISTURE TOO GREAT TO KEEP MENTION. EXPECT A RAPID MELT OFF OF SNOW PACK AS WINDS GUST INTO THE 30-40 MPH RANGE AT TIMES. && .PREV DISCUSSION... /ISSUED 642 AM EST SAT FEB 7 2009/ AVIATION... THE MAIN CHALLENGES THIS TAF PERIOD INCLUDE TIMING AND DURATION OF LOW CLOUDS AND ANY FOG. HAVE HAD TO BACK OFF WITH THE MORE PESSIMISTIC CIG/VSBY CONDITIONS EARLY IN LIEU OF A LATER START TIME. STILL EXPECT CONDITIONS TO DETERIORATE TODAY AS DEEPER MOISTURE SPREADS NORTHEAST. A FRONT WILL MOVE ACROSS THE AREA TONIGHT...HELPING TO CLEAR ANY REMAINING FOG. SHORT TERM... TODAY THROUGH SUNDAY NIGHT...STRONG WARM AIR ADVECTION WAS ONGOING EARLY...WITH CLOUDS TRYING TO FORM AS MOISTURE WAS SPREADING NORTHEAST ACROSS THE AREA. SOME CHALLENGES EARLY INCLUDE ANY FOG DEVELOPMENT ALONG WITH THE CHANCE FOR DRIZZLE. AIRCRAFT/TAMDAR OBS AND UPSTREAM UPPER AIR SOUNDINGS INDICATED A MOIST LAYER UNDER 900 MB. THE MIXING OF THE LOWER LAYER HAS BEEN SIGNIFICANT THAT LIMITED VERY LOW CLOUDS AND FOG WERE ABLE TO FORM. BELIEVE ADDITIONAL LOW LEVEL MOISTURE SPREADING INTO THE AREA WILL HELP AREAS OF FOG AND DRIZZLE TO DEVELOP TODAY...ALTHOUGH HAVE BACKED OFF WITH THE ONSET OF FOG. A COLD FRONT SHOULD MOVE ACROSS THE AREA TONIGHT...CLEARING OUT ANY REMAINING FOG FROM NW TO SE. SUNDAY SHOULD BE COOL AND DRY AS THE FRONT BECOME STATIONARY SOUTH OF THE AREA. NORTH WINDS SUNDAY WILL BECOME SOUTHEAST SUNDAY NIGHT AS THE SURFACE HIGH MOVES SOUTHEAST OF THE AREA. KEPT COLDEST TEMPS SUNDAY NIGHT OVER NORTHEAST AREAS WHERE SKIES SHOULD CLEAR OVER DEEPER SNOWCOVER. LONG TERM... MONDAY THROUGH FRIDAY. CONFIDENCE FINALLY BOOSTED WRT LONG TERM FCST PROMPTING A FAIR AMOUNT OF TWEAKS GIVEN LATEST TRENDS. NAM/GFS/ECMWF IN FAIR AGREEMENT ON LARGE SCALE THROUGH AT LEAST F120. TWO LARGE SCALE FEATURES TO CONTEND WITH...FIRST CUTOFF OF CNTL CA COAST WITH STRONG PVU ANOMALY OF 8-12 PV UNITS IN 400-200MB LYR/STRONG STRATOSPHERIC INTRUSION TO AFFORD SE CO CYCLOGENESIS BY F48/SUN EVE AS SECOND UPSTREAM BROAD TROF NR 160W SURGES EWD KICKING ML/UL SUPPORT INTO INTMTN REGION. WHILE NEG TILTED TROF INTO NRN PLAINS BY MON EVE TO FAVOR SFC LOW TRACK INTO NRN PLAINS/MN RGN BY TUE AM...CONCERN PRIMARILY FOCUSED ON LLJ IMPINGENT UPON XTRMLY MOIST AIRMASS TO S/SW. INITIAL 850-450 MB LYR QUITE DRY AND ACK TO BE LIMITING FACTOR FOR POP CHCS MON AND CERTAINLY A LESSER QPF EVENT THAN EARLIER THOUGHT PSBL. HAVE CONTD TREND OF PAST 24 HOURS IN SLOWING PRECIP ARRIVAL AND PROVIDED SPATIAL RESOLUTION TO POP/WX KEEPING HIR PROBS TAGGED TO NERN NOSE OF LLJ W/STRONGEST LLVL MFLUX/CONVERGENCE/LIFT. STILL HIER POPS THAN MOS GUIDANCE SUGGESTS WITH WDPSRD PRECIP SIGNAL LT MON AFTN INTO MON NIGHT AS CONCERN RESTS WITH E-W BREADTH OF MOISTURE PLUME LAYED OUT ACRS OH/TN VLYS COMBINED WITH GOMEX ADVECTION TO BE TAPPED WITH PWAT ALREADY 203 PERCENT OF NORMAL AT KOUN FRI EVE WITH SHORT TERM PD CLIPPER DRAWING 6-7 G/KG 1000-850 NEWD INTO CWA. BY 12 UTC SUN BROAD SWATH OF 0.8 TO 1.1 PWAT FM OK-WV WITH WARM FNT LIFTNG NE INTO SWRN CWA BY LT MON AM. BRIEF DISCONNECT WITH DEEPER MSTR SEEN IN 1000-700/700-400 MB RH DIFFERENTIALS WITH DRY SLOT ROTATING THRU CWA FOLLOWING WARM FNTL PASSAGE...THOUGH TOO EARLY TO AFFORD TEMPORAL DETAIL OF LULL IN PRECIP BEFORE RAPIDLY APPROACHING WARM OCCLUSION BRINGS RETURN OF DEEPER THETA-E AIR WITH PWAT GT 2SD AND BEST RAFL CHCS FOR PSBL RELEASE OF RUNOFF...QPF/SNOWMELT MONDAY NIGHT. MOIST AIR FINALLY SHUNTED TO OHIO VALLEY ON TUE AND RELEGATED RAIN MENTION TO SRN CWA ONLY. NEXT SYSTEM TO DIG FURTHER SOUTH THAN PREV...AND WHILE GFS IS STILL FURTHER SE THAN ECMWF ONLY BY SLIGHT/LESSER AMOUNT AND NOT WROUGHT WITH FEEDBACK IN COMPARO TO 24 HRS PRIOR. GIVEN A BIT HIR CONFIDENCE HAVE STAIR-STEPPED POPS CENTERED AROUND WEDS LKLY MENTION. SHOULD EXCESSV RAFL MON NIGHT NOT COME TO FRUITION A RIPENED SNOWPACK AND WARMER TEMPS MAY ALLOW FOR A SLOWER RELEASE/BROADER LESS PEAKED HYDROGRAPHS THOUGH SIG FLDG POTNL TO CONT. RAISED TEMPS SIG MON-TUE NIGHT AND GIVEN WARM MOIST SURGE AND RAFL HAVE SQUELCHED DIURNAL SWINGS WITH GTR RISE TO OVERNIGHT LOWS. TIMING OF CHANGEOVER TO RAIN/SNOW STILL LOOKS GOOD AND SHOULD BE NO EARLIER THAN GFS DEPICTION WITH WARM LYR DEPTH SUPPORTING RAIN UNTIL DAYBREAK THU. LITTLE IF ANY CHANGES REQRD DY6-7. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...SKIPPER LONG TERM...MURPHY AVIATION...SKIPPER UPDATE...SIMPSON
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
642 AM EST SAT FEB 7 2009 .AVIATION... THE MAIN CHALLENGES THIS TAF PERIOD INCLUDE TIMING AND DURATION OF LOW CLOUDS AND ANY FOG. HAVE HAD TO BACK OFF WITH THE MORE PESSIMISTIC CIG/VSBY CONDITIONS EARLY IN LIEU OF A LATER START TIME. STILL EXPECT CONDITIONS TO DETERIORATE TODAY AS DEEPER MOISTURE SPREADS NORTHEAST. A FRONT WILL MOVE ACROSS THE AREA TONIGHT...HELPING TO CLEAR ANY REMAINING FOG. && .PREV DISCUSSION... /ISSUED 446 AM EST SAT FEB 7 2009/ SHORT TERM... TODAY THROUGH SUNDAY NIGHT...STRONG WARM AIR ADVECTION WAS ONGOING EARLY...WITH CLOUDS TRYING TO FORM AS MOISTURE WAS SPREADING NORTHEAST ACROSS THE AREA. SOME CHALLENGES EARLY INCLUDE ANY FOG DEVELOPMENT ALONG WITH THE CHANCE FOR DRIZZLE. AIRCRAFT/TAMDAR OBS AND UPSTREAM UPPER AIR SOUNDINGS INDICATED A MOIST LAYER UNDER 900 MB. THE MIXING OF THE LOWER LAYER HAS BEEN SIGNIFICANT THAT LIMITED VERY LOW CLOUDS AND FOG WERE ABLE TO FORM. BELIEVE ADDITIONAL LOW LEVEL MOISTURE SPREADING INTO THE AREA WILL HELP AREAS OF FOG AND DRIZZLE TO DEVELOP TODAY...ALTHOUGH HAVE BACKED OFF WITH THE ONSET OF FOG. A COLD FRONT SHOULD MOVE ACROSS THE AREA TONIGHT...CLEARING OUT ANY REMAINING FOG FROM NW TO SE. SUNDAY SHOULD BE COOL AND DRY AS THE FRONT BECOME STATIONARY SOUTH OF THE AREA. NORTH WINDS SUNDAY WILL BECOME SOUTHEAST SUNDAY NIGHT AS THE SURFACE HIGH MOVES SOUTHEAST OF THE AREA. KEPT COLDEST TEMPS SUNDAY NIGHT OVER NORTHEAST AREAS WHERE SKIES SHOULD CLEAR OVER DEEPER SNOWCOVER. LONG TERM... MONDAY THROUGH FRIDAY. CONFIDENCE FINALLY BOOSTED WRT LONG TERM FCST PROMPTING A FAIR AMOUNT OF TWEAKS GIVEN LATEST TRENDS. NAM/GFS/ECMWF IN FAIR AGREEMENT ON LARGE SCALE THROUGH AT LEAST F120. TWO LARGE SCALE FEATURES TO CONTEND WITH...FIRST CUTOFF OF CNTL CA COAST WITH STRONG PVU ANOMALY OF 8-12 PV UNITS IN 400-200MB LYR/STRONG STRATOSPHERIC INTRUSION TO AFFORD SE CO CYCLOGENESIS BY F48/SUN EVE AS SECOND UPSTREAM BROAD TROF NR 160W SURGES EWD KICKING ML/UL SUPPORT INTO INTMTN REGION. WHILE NEG TILTED TROF INTO NRN PLAINS BY MON EVE TO FAVOR SFC LOW TRACK INTO NRN PLAINS/MN RGN BY TUE AM...CONCERN PRIMARILY FOCUSED ON LLJ IMPINGENT UPON XTRMLY MOIST AIRMASS TO S/SW. INITIAL 850-450 MB LYR QUITE DRY AND ACK TO BE LIMITING FACTOR FOR POP CHCS MON AND CERTAINLY A LESSER QPF EVENT THAN EARLIER THOUGHT PSBL. HAVE CONTD TREND OF PAST 24 HOURS IN SLOWING PRECIP ARRIVAL AND PROVIDED SPATIAL RESOLUTION TO POP/WX KEEPING HIR PROBS TAGGED TO NERN NOSE OF LLJ W/STRONGEST LLVL MFLUX/CONVERGENCE/LIFT. STILL HIER POPS THAN MOS GUIDANCE SUGGESTS WITH WDPSRD PRECIP SIGNAL LT MON AFTN INTO MON NIGHT AS CONCERN RESTS WITH E-W BREADTH OF MOISTURE PLUME LAYED OUT ACRS OH/TN VLYS COMBINED WITH GOMEX ADVECTION TO BE TAPPED WITH PWAT ALREADY 203 PERCENT OF NORMAL AT KOUN FRI EVE WITH SHORT TERM PD CLIPPER DRAWING 6-7 G/KG 1000-850 NEWD INTO CWA. BY 12 UTC SUN BROAD SWATH OF 0.8 TO 1.1 PWAT FM OK-WV WITH WARM FNT LIFTNG NE INTO SWRN CWA BY LT MON AM. BRIEF DISCONNECT WITH DEEPER MSTR SEEN IN 1000-700/700-400 MB RH DIFFERENTIALS WITH DRY SLOT ROTATING THRU CWA FOLLOWING WARM FNTL PASSAGE...THOUGH TOO EARLY TO AFFORD TEMPORAL DETAIL OF LULL IN PRECIP BEFORE RAPIDLY APPROACHING WARM OCCLUSION BRINGS RETURN OF DEEPER THETA-E AIR WITH PWAT GT 2SD AND BEST RAFL CHCS FOR PSBL RELEASE OF RUNOFF...QPF/SNOWMELT MONDAY NIGHT. MOIST AIR FINALLY SHUNTED TO OHIO VALLEY ON TUE AND RELEGATED RAIN MENTION TO SRN CWA ONLY. NEXT SYSTEM TO DIG FURTHER SOUTH THAN PREV...AND WHILE GFS IS STILL FURTHER SE THAN ECMWF ONLY BY SLIGHT/LESSER AMOUNT AND NOT WROUGHT WITH FEEDBACK IN COMPARO TO 24 HRS PRIOR. GIVEN A BIT HIR CONFIDENCE HAVE STAIR-STEPPED POPS CENTERED AROUND WEDS LKLY MENTION. SHOULD EXCESSV RAFL MON NIGHT NOT COME TO FRUITION A RIPENED SNOWPACK AND WARMER TEMPS MAY ALLOW FOR A SLOWER RELEASE/BROADER LESS PEAKED HYDROGRAPHS THOUGH SIG FLDG POTNL TO CONT. RAISED TEMPS SIG MON-TUE NIGHT AND GIVEN WARM MOIST SURGE AND RAFL HAVE SQUELCHED DIURNAL SWINGS WITH GTR RISE TO OVERNIGHT LOWS. TIMING OF CHANGEOVER TO RAIN/SNOW STILL LOOKS GOOD AND SHOULD BE NO EARLIER THAN GFS DEPICTION WITH WARM LYR DEPTH SUPPORTING RAIN UNTIL DAYBREAK THU. LITTLE IF ANY CHANGES REQRD DY6-7. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...SKIPPER LONG TERM...MURPHY AVIATION...SKIPPER
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
446 AM EST SAT FEB 7 2009 .SHORT TERM... TODAY THROUGH SUNDAY NIGHT...STRONG WARM AIR ADVECTION WAS ONGOING EARLY...WITH CLOUDS TRYING TO FORM AS MOISTURE WAS SPREADING NORTHEAST ACROSS THE AREA. SOME CHALLENGES EARLY INCLUDE ANY FOG DEVELOPMENT ALONG WITH THE CHANCE FOR DRIZZLE. AIRCRAFT/TAMDAR OBS AND UPSTREAM UPPER AIR SOUNDINGS INDICATED A MOIST LAYER UNDER 900 MB. THE MIXING OF THE LOWER LAYER HAS BEEN SIGNIFICANT THAT LIMITED VERY LOW CLOUDS AND FOG WERE ABLE TO FORM. BELIEVE ADDITIONAL LOW LEVEL MOISTURE SPREADING INTO THE AREA WILL HELP AREAS OF FOG AND DRIZZLE TO DEVELOP TODAY...ALTHOUGH HAVE BACKED OFF WITH THE ONSET OF FOG. A COLD FRONT SHOULD MOVE ACROSS THE AREA TONIGHT...CLEARING OUT ANY REMAINING FOG FROM NW TO SE. SUNDAY SHOULD BE COOL AND DRY AS THE FRONT BECOME STATIONARY SOUTH OF THE AREA. NORTH WINDS SUNDAY WILL BECOME SOUTHEAST SUNDAY NIGHT AS THE SURFACE HIGH MOVES SOUTHEAST OF THE AREA. KEPT COLDEST TEMPS SUNDAY NIGHT OVER NORTHEAST AREAS WHERE SKIES SHOULD CLEAR OVER DEEPER SNOWCOVER. && .LONG TERM... MONDAY THROUGH FRIDAY. CONFIDENCE FINALLY BOOSTED WRT LONG TERM FCST PROMPTING A FAIR AMOUNT OF TWEAKS GIVEN LATEST TRENDS. NAM/GFS/ECMWF IN FAIR AGREEMENT ON LARGE SCALE THROUGH AT LEAST F120. TWO LARGE SCALE FEATURES TO CONTEND WITH...FIRST CUTOFF OF CNTL CA COAST WITH STRONG PVU ANOMALY OF 8-12 PV UNITS IN 400-200MB LYR/STRONG STRATOSPHERIC INTRUSION TO AFFORD SE CO CYCLOGENESIS BY F48/SUN EVE AS SECOND UPSTREAM BROAD TROF NR 160W SURGES EWD KICKING ML/UL SUPPORT INTO INTMTN REGION. WHILE NEG TILTED TROF INTO NRN PLAINS BY MON EVE TO FAVOR SFC LOW TRACK INTO NRN PLAINS/MN RGN BY TUE AM...CONCERN PRIMARILY FOCUSED ON LLJ IMPINGENT UPON XTRMLY MOIST AIRMASS TO S/SW. INITIAL 850-450 MB LYR QUITE DRY AND ACK TO BE LIMITING FACTOR FOR POP CHCS MON AND CERTAINLY A LESSER QPF EVENT THAN EARLIER THOUGHT PSBL. HAVE CONTD TREND OF PAST 24 HOURS IN SLOWING PRECIP ARRIVAL AND PROVIDED SPATIAL RESOLUTION TO POP/WX KEEPING HIR PROBS TAGGED TO NERN NOSE OF LLJ W/STRONGEST LLVL MFLUX/CONVERGENCE/LIFT. STILL HIER POPS THAN MOS GUIDANCE SUGGESTS WITH WDPSRD PRECIP SIGNAL LT MON AFTN INTO MON NIGHT AS CONCERN RESTS WITH E-W BREADTH OF MOISTURE PLUME LAYED OUT ACRS OH/TN VLYS COMBINED WITH GOMEX ADVECTION TO BE TAPPED WITH PWAT ALREADY 203 PERCENT OF NORMAL AT KOUN FRI EVE WITH SHORT TERM PD CLIPPER DRAWING 6-7 G/KG 1000-850 NEWD INTO CWA. BY 12 UTC SUN BROAD SWATH OF 0.8 TO 1.1 PWAT FM OK-WV WITH WARM FNT LIFTNG NE INTO SWRN CWA BY LT MON AM. BRIEF DISCONNECT WITH DEEPER MSTR SEEN IN 1000-700/700-400 MB RH DIFFERENTIALS WITH DRY SLOT ROTATING THRU CWA FOLLOWING WARM FNTL PASSAGE...THOUGH TOO EARLY TO AFFORD TEMPORAL DETAIL OF LULL IN PRECIP BEFORE RAPIDLY APPROACHING WARM OCCLUSION BRINGS RETURN OF DEEPER THETA-E AIR WITH PWAT GT 2SD AND BEST RAFL CHCS FOR PSBL RELEASE OF RUNOFF...QPF/SNOWMELT MONDAY NIGHT. MOIST AIR FINALLY SHUNTED TO OHIO VALLEY ON TUE AND RELEGATED RAIN MENTION TO SRN CWA ONLY. NEXT SYSTEM TO DIG FURTHER SOUTH THAN PREV...AND WHILE GFS IS STILL FURTHER SE THAN ECMWF ONLY BY SLIGHT/LESSER AMOUNT AND NOT WROUGHT WITH FEEDBACK IN COMPARO TO 24 HRS PRIOR. GIVEN A BIT HIR CONFIDENCE HAVE STAIR-STEPPED POPS CENTERED AROUND WEDS LKLY MENTION. SHOULD EXCESSV RAFL MON NIGHT NOT COME TO FRUITION A RIPENED SNOWPACK AND WARMER TEMPS MAY ALLOW FOR A SLOWER RELEASE/BROADER LESS PEAKED HYDROGRAPHS THOUGH SIG FLDG POTNL TO CONT. RAISED TEMPS SIG MON-TUE NIGHT AND GIVEN WARM MOIST SURGE AND RAFL HAVE SQUELCHED DIURNAL SWINGS WITH GTR RISE TO OVERNIGHT LOWS. TIMING OF CHANGEOVER TO RAIN/SNOW STILL LOOKS GOOD AND SHOULD BE NO EARLIER THAN GFS DEPICTION WITH WARM LYR DEPTH SUPPORTING RAIN UNTIL DAYBREAK THU. LITTLE IF ANY CHANGES REQRD DY6-7. && .AVIATION... THE MAIN CHALLENGES THIS TAF PERIOD IS TIMING AND DURATION OF LOW CLOUDS AND ANY FOG. LIGHT FOG AND LOW CLOUDS WERE DEVELOPING UPSTREAM. THESE CLOUDS HAD SPREAD INTO SBN BEFORE 06Z. PREFER THE MORE PESSIMISTIC NAM/WRF GUIDANCE. FOG AND LOW CLOUDS SHOULD CONTINUE TO DEVELOP AND SPREAD NORTHEAST AS MOIST AIR SPREADS OVER SNOW PACK. WILL KEEP IFR/MVFR CIGS THROUGHOUT THE TAF PERIOD...WITH LOW CLOUDS DEVELOPING/SPREADING INTO FWA BEFORE 12Z. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...SKIPPER LONG TERM...MURPHY AVIATION...SKIPPER
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
125 AM EST SAT FEB 7 2009 .AVIATION... THE MAIN CHALLENGES THIS TAF PERIOD IS TIMING AND DURATION OF LOW CLOUDS AND ANY FOG. LIGHT FOG AND LOW CLOUDS WERE DEVELOPING UPSTREAM. THESE CLOUDS HAD SPREAD INTO SBN BEFORE 06Z. PREFER THE MORE PESSIMISTIC NAM/WRF GUIDANCE. FOG AND LOW CLOUDS SHOULD CONTINUE TO DEVELOP AND SPREAD NORTHEAST AS MOIST AIR SPREADS OVER SNOW PACK. WILL KEEP IFR/MVFR CIGS THROUGHOUT THE TAF PERIOD...WITH LOW CLOUDS DEVELOPING/SPREADING INTO FWA BEFORE 12Z. && .PREV DISCUSSION... /ISSUED 839 PM EST FRI FEB 6 2009/ UPDATE... GOING FORECAST IN GOOD SHAPE THIS EVENING WITH ONLY MINOR UPDATES NEEDED. MAIN CHANGE WAS TO LOWER TEMPERATURES OVER NORTHEASTERN AREAS THIS EVENING /WHICH WILL END UP IN LOWER OVERNIGHT LOWS GIVEN RISING TEMP TRENDS LATER TONIGHT/ AS TEMPS HAVE FALLEN INTO THE UPPER 20S HERE AS LLEVEL SOUTHERLY FLOW IS WEAKEST HERE...AND CLOUDINESS IS ALSO AT A MINIMUM. HAVE REMOVED ANY POPS FOR THE OVERNIGHT GIVEN VERY LITTLE CHANCE FOR MEASURABLE PRECIP AND WHILE I KEPT DZ IN THE AFTER MIDNIGHT PORTION OF THE FORECAST... HAVE LOW CONFIDENCE IN MUCH DRIZZLE GIVEN VERY SHALLOW MOISTURE WITH MUCH OF THE LIFT REMAINING ABOVE THE MOIST LAYER. HOWEVER...THE MOIST LAYER WILL DEEPEN WITH TIME...AND CERTAINLY COULD SEE FOG DEVELOPMENT GIVEN DEWPOINTS RISING ABOVE THE FREEZING MARK. INTERESTING QUESTION OVERNIGHT IS HOW MUCH THE STRENGTHENING LLEVEL SOUTHERLY FLOW DISRUPTS FOG/STRATUS DEVELOPMENT. RIGHT NOW FEEL THAT FOG/STRATUS STILL VERY POSSIBLE GIVEN THE SNOWPACK...BUT THERE WILL BE QUITE A BIT OF MIXING TO OVERCOME. EVENING TAMDAR FLIGHTS SUGGEST THAT WE ARE NEARING SATURATION AT AROUND 950 MB...SO IT MAY VERY WELL BE THAT A LARGE AREA GOES FROM MCLEAR TO OVC IN STRATUS IN THE MANNER OF AN HOUR OR TWO. IF ANY DZ DOES OCCUR...IT SHOULD BE LATE ENOUGH FOR ALL AREAS TO BE ABOVE FREEZING...SO FZDZ DOES NOT LOOK LIKE A THREAT. UPDATED PRODUCTS/GRIDS ARE OUT. PREV DISCUSSION... /ISSUED 354 PM EST FRI FEB 6 2009/ SHORT TERM... THROUGH SAT NIGHT SIG LL THERMAL RIDGING WILL CONT TO ADVT EWD OVERNIGHT DOWNSTREAM OF LEAD SW TROUGH EJECTING THROUGH NRN PLAINS. AS SUCH AND IN LIGHT OF DEEPENING MIXED LYR...XPC TEMPS WILL CONT TO WARM OVERNIGHT. EVENTUAL ADDN OF SNOW MELT DERIVED LL MSTR ESP ALG WRN/SRN FLANK OF DEEP SNOW FIELD WILL AID IN NWD EXPANSION OF STRATUS...NOW INTO FAR SRN IL ATTM...LTR THIS EVENING. INCREASING MSTR DEPTH AND LARGE SCALE ASCENT AHD OF EJECTING SW WILL ALSO LEAD TO AT LEAST DZ IF NOT LT SHRA LATE TONIGHT. THIS MAY RESULT IN A DENSE FOG THREAT SAT YET DEGREE OF MODEL IMPLIED TURBULENT MIXING AND RATHER INTENSE GRADIENT FLW WOULD SUGGEST OTHERWISE. WILL KEEP W/AREA FOG/DZ MENTION AT THIS POINT AND LOW CHC POPS FOR HIGH PROB/LOW QPF EVENT. TEMPS SAT REMAIN PROBLEMATIC ESP W/XPCD LOW STRATUS DVLPMNT OVERNIGHT AND CONTG SAT ALG W/DEGREE OF POTENTIAL MIXING W/VRY WARM AIR ALOFT AT HAND. NEWER 12Z NUMBERS A BIT WARMER AND SFC TRAJECTORIES EVEN WARMER W/OBSVD TEMPS NR 60 EARLY THIS AFTN OVR NE MO/WRN IL. WILL SHADE A BIT WARMER BUT WHICH STILL FITS WITHIN COOLER RANGE OF GUIDANCE TEMPS. LONG TERM... SUNDAY THROUGH FRIDAY. FORECAST ISSUES REMAIN WITH LONGWAVE TROUGH SITTING OVER THE SW AND TIMING/STRENGTH/TRACK OF AN INITAL PIECE OF ENERGY FOR MONDAY INTO MONDAY NIGHT AND THEN THE TROUGH KICKING OUT FOR MID WEEK. GIVEN WHAT IS BEING SEEN ALREADY TODAY WITH WARM AIR OVERCOMING THE COLD BL...SUNDAY MAY NOT BE AS COLD AS PREVIOUSLY THOUGHT. NEW MEX/MAV NUMBERS SHOWING HIGHS ON SUNDAY IN THE MID 40S BUT NAM MORE IN THE MID TO UPPER 30S. SINCE SOME QUESTION REMAINS AS TO HOW FAR SOUTH THE COLD AIR MAKES IT INTO THE AREA WILL KEEP TEMPS AS IT FOR SUNDAY AND SUNDAY NIGHT. MODELS DO SUGGEST A SLOWER ARRIVAL TIME OF ANY PRECIP AND AS A RESULT HAVE WENT WITH CONSENSUS AROUND US AND REMOVED ANY MENTION OF PRECIP FOR LATE SUNDAY NIGHT IN THE SW. MONDAY WILL BRING THE FIRST WAVE PASSING WELL TO OUR NW. THIS WILL ALLOW THE GULF TO BEGIN TO OPEN AND A PLUME OF DEWPTS POTENTIALLY WELL INTO THE 50S TO BEGIN TO MAKE A RUN FOR THE AREA. WARM FRONT WILL TAKE SHAPE ACROSS THE AREA MONDAY AFTERNOON AND NIGHT. COULD BE A FEW ROUNDS OF POTENTIAL PRECIP WITH BEST TIME FRAME MORE THAN LIKELY MONDAY NIGHT. AS A RESULT HAVE EXPANDED POPS INTO ALL ON MONDAY NIGHT. TUESDAY WILL LIKELY SEE A BRIEF LULL AS MAIN ENERGY REMAINS NORTH AND SW OF THE AREA AS WE AWAIT THE MAIN TROUGH COMING OUT OF THE SW. JET STREAK OF AT LEAST 120 KTS WILL ALLOW FOR RAPID INTENSIFICATION OF THE SFC LOW WITH THE ECMWF DEEPENING A 999 LOW OVER EASTERN OKLAHOMA AT 12Z WEDS TO A 986 LOW BY 12Z THURS AS IT TRACK ACROSS THE CWA. GFS IN THE SAME TIME FRAME TAKES A 1001 LOW OVER EASTERN KANSAS AND INTENSIFIES TO 977 LOW OVER NORTH LAKE HURON BY 12Z THU. ABUNDANT GULF MSTR SHOULD BE FLOWING IN BY THIS TIME...WITH DEWPOINTS INTO THE 50S AND HIGHS WELL INTO THE 50S AND POSSIBLY CLOSE TO 60 NOT OUT OF THE REALM OF POSSIBILITY. HAVE INCREASED POPS TO HIGH CHC WEDS AND WEDS NGT. POTENTIAL FOR SIG QPF WILL EXIST WITH THIS SYSTEM...AS WELL AS STRONG WINDS AND POTENTIALLY THUNDERSTORMS. ESF THAT WAS SENT THIS MORNING HAS THE HYDRO THREAT IN HAND AND WILL LEAVE AS IS FOR NOW. COLD AIR COMES BACK IN LATE WEDS NGT INTO THURS WITH 1000-850 MB THICKNESSES DROPPING BELOW 1300. ANY LINGERING PRECIP WILL CHANGE OVER TO SNOW BUT EXACT TIMING DIFFERENCES WARRANTS GOING RAIN OR SNOW IN GRIDS ON THURSDAY. THE FRONT WILL NOT BRING ANY BITTER COLD AIR WITH IT BUT SHOULD RETURN TEMPS BACK TO MORE SEASONABLE LEVELS IN THE MID 30S. CONDITIONS SHOULD CALM DOWN INTO THURSDAY NIGHT AND FRIDAY SO WILL GO WITH A DRY FORECAST. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...HOLSTEN LONG TERM...FISHER AVIATION...SKIPPER
SEE PREVIOUS FORECAST DISCUSSION.

&& .AVIATION... FOR THE 00Z TAFS...BIGGEST CHALLENGE IN THE TAFS IS TIMING FLIGHT RESTRICTION CIGS. MODELS FAIRLY CONSISTENT IN BRINGING DEEPER LOW LEVEL MOISTURE OVER TAF SITES AFTER MIDNIGHT TONIGHT...HOWEVER UPSTREAM THE DEEPER LOW LEVEL MOISTURE IS NOT CURRENTLY ASSOCIATED WITH LOW LEVEL STRATUS SO THINK THE MODELS MAY BE TOO AGGRESSIVE BRINGING CIGS DOWN INTO MVFR/IFR RANGE TONIGHT. BACKED OFF A FEW HOURS ON TIMING OF MVFR CIGS AND ADDED IN SO IFR CIGS WHEN MAIN STORM SYSTEM PULLS OUT OVER EASTERN KS TOMORROW MORNING. LOW LEVEL CIGS EXPECTED TO BE SCOURED OUT BY MONDAY AFTERNOON AS A FRONTAL BOUNDARY MOVES THROUGH. WINDS EXPECTED TO REMAIN VERY STRONG FOR LIGHT AIRCRAFT ON MONDAY WITH SOUTHERLY WINDS GUSTING ABOVE 40 MPH AT TIMES. CAVANAUGH && .PREV DISCUSSION... /ISSUED 315 PM CST SUN FEB 8 2009/ DISCUSSION... PRECIPITATION CHANCES AND WINDS ARE THE MAIN CONCERNS FOR THE TONIGHT AND MONDAY PORTION OF THE FORECAST. MORNING UPPER AIR OBSERVATIONS INCLUDED A 120KT JET STREAK SAMPLED BY AIRCRAFT IN WESTERN MEXICO ON THE SSE PORTION OF AN UPPER LOW OVER THE SOUTHWEST CONUS. TUS REPORTED A 100M 500MB HEIGHT FALL AS THIS SYSTEM MOVES EAST TOWARD THE ROCKIES. 850MB MAP AGAIN SHOWED RATHER WARM TEMPS FOR MUCH OF THE AREA FOR EARLY FEBRUARY ALONG WITH 7-10C DEWPOINTS FROM SGF AND DDC ON SOUTH. 20Z SURFACE DATA SUGGESTS WARM FRONT IN SOUTHERN KANSAS WITH TEMPS APPROACHING 70F....WITH LOW TO MID 40S HOLDING IN FAR NORTHEAST KANSAS. 3-HOUR PRESSURE FALLS WERE IN THE 4-5MB RANGE...SOME 2-3MB ABOVE NORMAL. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE SOUTHWEST UPPER TROF SURGING NORTHEAST INTO THE NORTHERN PLAINS WHILE DEEPENING AND BECOMING TONIGHT INTO MONDAY AFTERNOON. ISENTROPIC LIFT LOCALLY IS NOT VERY STRONG...AND MID LEVEL MOISTURE IS RATHER LACKING THROUGH THE LATE NIGHT UNTIL THE STRONGER Q-G FORCING MOVES IN...AND HAVE RESULTANTLY DROPPED POPS A BIT FOR CENTRAL AND EASTERN AREAS FOR TONIGHT. INSTABILITY IS NOT VERY IMPRESSIVE...BIT WILL MAINTAIN THUNDER MENTION. BEST FORCING MAY SPLIT THE CWA SO WILL KEEP SOME DOUBT IN EVERYONE GETTING WET LATE TONIGHT INTO MONDAY MORNING. INCREASING AND VEERING LOW LEVEL WINDS RESPONDING TO CYCLOGENESIS TO THE WEST WILL PUSH THE WARM FRONT NORTH THROUGH THE CWA...AND SHOULD KEEP TEMPS RATHER WARM. PRESSURE GRADIENT BY DAWN APPROACHES 8MB ACROSS THE CWA...BUT BACKED NATURE OF WINDS AND LIMITED MIXING DEPTHS SHOULD KEEP SPEEDS BELOW ADVISORY LEVELS. AS THE SYSTEM PUSHES NORTHEAST...WINDS WILL CONTINUE TO BACK AND BECOME MORE UNIDIRECTIONAL FOR INCREASED WIND POTENTIAL...ESPECIALLY IN THE AFTERNOON. MIXING DEPTHS MAY REACH INTO THE 55KT WINDS AROUND 800MB...SO AN ADVISORY SEEMS IN ORDER. WITH SOME LOW LEVEL MOISTURE REMAINING...WILL NEED TO WATCH FOR ADDITIONAL THUNDER DEVELOPMENT FOR THE AFTERNOON...THOUGH LIMITED INSTABILITY SHOULD KEEP MUCH IF ANY SEVERE CONVECTION IN CHECK. DIDNT ALTER TEMPS MUCH. 65 NEXT SHORTWAVE ON TRACK TO MOVE ACROSS THE FORECAST AREA TUESDAY NIGHT AND EARLY WEDNESDAY. THE GFS APPEARS TO BE AN OUTLIER WITH PROBLEMS ARISING FROM CONVECTIVE FEEDBACK TUESDAY AFTERNOON. THEREFORE USED THE NAM/UKMET/ECMWF WHICH ARE SIMILAR IN THE TRACK AND STRENGTH OF THE SFC LOW ACROSS NORTHEAST OK AND SOUTHEAST KS. MODELS SHOW STRONG QG FORCING WITH THE DEVELOPMENT OF A TROWAL FEATURE TO THE NORTHWEST OF THE SFC LOW MOVING ACROSS THE FORECAST AREA BETWEEN 06Z AND 18Z WEDNESDAY. NAM FORECAST SOUNDINGS KEEP SFC TEMPS GENERALLY AROUND 40 TUESDAY NIGHT WITHIN THE AXIS OF HEAVIER PRECIP INDICATING THAT MOST OF THE PRECIP WILL REMAIN LIQUID. BUT THIS WILL NEED TO BE MONITORED AS A COUPLE DEGREES COOLER COULD MEAN A DECENT BAND OF SNOW ACROSS PARTS OF THE AREA. INITIALLY MID LEVEL LAPSE RATES ARE STEEP ENOUGH TO CONTINUE MENTION OF THUNDER TUESDAY NIGHT. FORECAST SOUNDINGS SHOW THIS POTENTIAL INSTABILITY DIMINISHING AS THE COLUMN BECOMES SATURATED BY 12Z WEDNESDAY. WAA AND MOSTLY SUNNY SKIES SHOULD ALLOW TEMPS TO WARM WELL ABOVE NORMAL FOR TUESDAY. WITH MODELS NOT OVERLY AGGRESSIVE WITH COLD AIR ON THE BACK SIDE AND SOME CLEARING WEDNESDAY AFTERNOON...THINK TEMPS WILL RECOVER INTO THE MID AND UPPER 40S FOR WEDNESDAY. EXPECT A BREAK FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT BEFORE THE NEXT SHORTWAVE BEGINS TO MOVE OUT INTO THE PLAINS. MODEL CONSISTENCY WITH THIS WAVE HAS SHOWN SOME UNCERTAINTY WITH THE TRACK OF THE SYSTEM. NEVERTHELESS LOOKS LIKE NEXT CHANCE FOR PRECIP WITH BE FRIDAY AND FRIDAY NIGHT. CONSIDERED REMOVING POPS FORM SATURDAY WITH THE ECMWF SHOWING SHORTWAVE RIDGING...BUT CONFIDENCE IN TIMING THESE SMALL SCALE FEATURES IS NOT HIGH ENOUGH. TEMP FORECAST FOR FRIDAY AND FRIDAY NIGHT IS RATHER CONSERVATIVE SO CONTINUED WITH A RAIN/SNOW FORECAST FRIDAY CHANGING TO SNOW FRIDAY NIGHT. MEDIUM RANGE MODELS ARE SHOWING ANOTHER WAVE MOVING OUT FROM THE ROCKIES ON SUNDAY. GIVEN THE ACTIVE PATTERN WENT AHEAD AND INSERTED SLIGHT CHANCE POOPS FOR SUNDAY...THOUGH THE 12Z ECMWF IS NOT NEARLY AS STRONG WITH THIS FOURTH WAVE AS THE PREVIOUS. CONFIDENCE IS LOW GIVEN POOR CONSISTENCY WITH THE GFS. STAYED CLOSE TO HPC AND CLIMO FOR TEMPS TO END THE FORECAST PERIOD. WOLTERS && .TOP WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY FROM 9 AM MONDAY TO 6 PM MONDAY FOR KSZ008-KSZ009- KSZ010-KSZ011-KSZ012-KSZ020-KSZ021-KSZ022-KSZ023-KSZ024-KSZ026- KSZ034-KSZ035-KSZ036-KSZ037-KSZ038-KSZ039-KSZ040-KSZ054-KSZ055- KSZ056-KSZ058-KSZ059. && $$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
315 PM CST SUN FEB 8 2009 .DISCUSSION... PRECIPITATION CHANCES AND WINDS ARE THE MAIN CONCERNS FOR THE TONIGHT AND MONDAY PORTION OF THE FORECAST. MORNING UPPER AIR OBSERVATIONS INCLUDED A 120KT JET STREAK SAMPLED BY AIRCRAFT IN WESTERN MEXICO ON THE SSE PORTION OF AN UPPER LOW OVER THE SOUTHWEST CONUS. TUS REPORTED A 100M 500MB HEIGHT FALL AS THIS SYSTEM MOVES EAST TOWARD THE ROCKIES. 850MB MAP AGAIN SHOWED RATHER WARM TEMPS FOR MUCH OF THE AREA FOR EARLY FEBRUARY ALONG WITH 7-10C DEWPOINTS FROM SGF AND DDC ON SOUTH. 20Z SURFACE DATA SUGGESTS WARM FRONT IN SOUTHERN KANSAS WITH TEMPS APPROACHING 70F....WITH LOW TO MID 40S HOLDING IN FAR NORTHEAST KANSAS. 3-HOUR PRESSURE FALLS WERE IN THE 4-5MB RANGE...SOME 2-3MB ABOVE NORMAL. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE SOUTHWEST UPPER TROF SURGING NORTHEAST INTO THE NORTHERN PLAINS WHILE DEEPENING AND BECOMING TONIGHT INTO MONDAY AFTERNOON. ISENTROPIC LIFT LOCALLY IS NOT VERY STRONG...AND MID LEVEL MOISTURE IS RATHER LACKING THROUGH THE LATE NIGHT UNTIL THE STRONGER Q-G FORCING MOVES IN...AND HAVE RESULTANTLY DROPPED POPS A BIT FOR CENTRAL AND EASTERN AREAS FOR TONIGHT. INSTABILITY IS NOT VERY IMPRESSIVE...BIT WILL MAINTAIN THUNDER MENTION. BEST FORCING MAY SPLIT THE CWA SO WILL KEEP SOME DOUBT IN EVERYONE GETTING WET LATE TONIGHT INTO MONDAY MORNING. INCREASING AND VEERING LOW LEVEL WINDS RESPONDING TO CYCLOGENESIS TO THE WEST WILL PUSH THE WARM FRONT NORTH THROUGH THE CWA...AND SHOULD KEEP TEMPS RATHER WARM. PRESSURE GRADIENT BY DAWN APPROACHES 8MB ACROSS THE CWA...BUT BACKED NATURE OF WINDS AND LIMITED MIXING DEPTHS SHOULD KEEP SPEEDS BELOW ADVISORY LEVELS. AS THE SYSTEM PUSHES NORTHEAST...WINDS WILL CONTINUE TO BACK AND BECOME MORE UNIDIRECTIONAL FOR INCREASED WIND POTENTIAL...ESPECIALLY IN THE AFTERNOON. MIXING DEPTHS MAY REACH INTO THE 55KT WINDS AROUND 800MB...SO AN ADVISORY SEEMS IN ORDER. WITH SOME LOW LEVEL MOISTURE REMAINING...WILL NEED TO WATCH FOR ADDITIONAL THUNDER DEVELOPMENT FOR THE AFTERNOON...THOUGH LIMITED INSTABILITY SHOULD KEEP MUCH IF ANY SEVERE CONVECTION IN CHECK. DIDNT ALTER TEMPS MUCH. 65 NEXT SHORTWAVE ON TRACK TO MOVE ACROSS THE FORECAST AREA TUESDAY NIGHT AND EARLY WEDNESDAY. THE GFS APPEARS TO BE AN OUTLIER WITH PROBLEMS ARISING FROM CONVECTIVE FEEDBACK TUESDAY AFTERNOON. THEREFORE USED THE NAM/UKMET/ECMWF WHICH ARE SIMILAR IN THE TRACK AND STRENGTH OF THE SFC LOW ACROSS NORTHEAST OK AND SOUTHEAST KS. MODELS SHOW STRONG QG FORCING WITH THE DEVELOPMENT OF A TROWAL FEATURE TO THE NORTHWEST OF THE SFC LOW MOVING ACROSS THE FORECAST AREA BETWEEN 06Z AND 18Z WEDNESDAY. NAM FORECAST SOUNDINGS KEEP SFC TEMPS GENERALLY AROUND 40 TUESDAY NIGHT WITHIN THE AXIS OF HEAVIER PRECIP INDICATING THAT MOST OF THE PRECIP WILL REMAIN LIQUID. BUT THIS WILL NEED TO BE MONITORED AS A COUPLE DEGREES COOLER COULD MEAN A DECENT BAND OF SNOW ACROSS PARTS OF THE AREA. INITIALLY MID LEVEL LAPSE RATES ARE STEEP ENOUGH TO CONTINUE MENTION OF THUNDER TUESDAY NIGHT. FORECAST SOUNDINGS SHOW THIS POTENTIAL INSTABILITY DIMINISHING AS THE COLUMN BECOMES SATURATED BY 12Z WEDNESDAY. WAA AND MOSTLY SUNNY SKIES SHOULD ALLOW TEMPS TO WARM WELL ABOVE NORMAL FOR TUESDAY. WITH MODELS NOT OVERLY AGGRESSIVE WITH COLD AIR ON THE BACK SIDE AND SOME CLEARING WEDNESDAY AFTERNOON...THINK TEMPS WILL RECOVER INTO THE MID AND UPPER 40S FOR WEDNESDAY. EXPECT A BREAK FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT BEFORE THE NEXT SHORTWAVE BEGINS TO MOVE OUT INTO THE PLAINS. MODEL CONSISTENCY WITH THIS WAVE HAS SHOWN SOME UNCERTAINTY WITH THE TRACK OF THE SYSTEM. NEVERTHELESS LOOKS LIKE NEXT CHANCE FOR PRECIP WITH BE FRIDAY AND FRIDAY NIGHT. CONSIDERED REMOVING POPS FORM SATURDAY WITH THE ECMWF SHOWING SHORTWAVE RIDGING...BUT CONFIDENCE IN TIMING THESE SMALL SCALE FEATURES IS NOT HIGH ENOUGH. TEMP FORECAST FOR FRIDAY AND FRIDAY NIGHT IS RATHER CONSERVATIVE SO CONTINUED WITH A RAIN/SNOW FORECAST FRIDAY CHANGING TO SNOW FRIDAY NIGHT. MEDIUM RANGE MODELS ARE SHOWING ANOTHER WAVE MOVING OUT FROM THE ROCKIES ON SUNDAY. GIVEN THE ACTIVE PATTERN WENT AHEAD AND INSERTED SLIGHT CHANCE POOPS FOR SUNDAY...THOUGH THE 12Z ECMWF IS NOT NEARLY AS STRONG WITH THIS FOURTH WAVE AS THE PREVIOUS. CONFIDENCE IS LOW GIVEN POOR CONSISTENCY WITH THE GFS. STAYED CLOSE TO HPC AND CLIMO FOR TEMPS TO END THE FORECAST PERIOD. WOLTERS && .AVIATION... INITIAL BAND OF MVFR CEILINGS SHOULD MOVE OUT EARLY IN THE FORECAST...AND EXPECT MORE TO DEVELOP OVERNIGHT...BUT NOT CONFIDENT ON TIMING AND PERSISTENCE OF IT AT THIS TIME. WILL GO AHEAD WITH A GENERAL MVFR DECK BEGINNING AROUND MIDNIGHT FOR NOW. PRECIP SHOULD ENTER THE AREA DURING THE DAYLIGHT HOURS OF MONDAY MORNING...BUT AGAIN PERSISTENCE IS NOT OBVIOUS AND WILL GO WITH VCSH. INCREASING LOW LEVEL RH LIKELY TO RESTRICT VISIBILITIES A BIT AS WELL. 65 && .TOP WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FROM 9AM UNTIL 6PM MONDAY FOR ENTIRE FORECAST AREA. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1039 AM EST SAT FEB 7 2009 .SYNOPSIS.../ISSUED AT 400 AM/ A WARMER BUT MORE ACTIVE WEATHER PATTERN WILL TAKE SHAPE ACROSS THE REGION THIS WEEKEND...AND PERSISTING INTO MUCH OF NEXT WEEK...AS A SERIES OF LOW PRESSURE SYSTEMS TRACKS FROM THE SOUTHWESTERN UNITED STATES INTO THE UPPER MIDWEST AND GREAT LAKES. THE FIRST SUCH SYSTEM WILL SEND A COLD FRONT ACROSS THE REGION LATER THIS AFTERNOON...BRINGING WITH IT SOME LIGHT RAIN AND DRIZZLE...ESPECIALLY THIS MORNING. TEMPERATURES WILL BRIEFLY COOL BACK DOWN TONIGHT AND SUNDAY. THEREAFTER...SEVERAL ROUNDS OF PRECIPITATION ARE FORECAST INTO THE MIDWEEK PERIOD ALONG WITH MUCH ABOVE NORMAL TEMPERATURES...AS SOUTHERLY WINDS DOMINATE ACROSS THE NORTHERN GREAT LAKES. && .SHORT TERM.../ISSUED AT 1039 AM/...THIS AFTERNOON 12Z SURFACE ANALYSIS SHOWS A 997MB SURFACE LOW OVER CENTRAL LAKE SUPERIOR...WITH SEVERAL FRONTAL BOUNDARIES EMANATING FROM THIS FEATURE. A WARM FRONT EXTENDS SOUTHEAST ACROSS EASTERN UPPER MI... ONE COLD FRONT EXTENDS SOUTH INTO LAKE MICHIGAN/SOUTHEAST WI/ NORTHWEST IL...A SECOND COLD FRONT RAN FROM NORTHWEST WI/SOUTHERN MN/CENTRAL SD. MAIN PUSH OF COLDER AIR BEHIND SECOND FRONT... INITIAL FRONT MAINLY MARKS EDGE OF DRIER LOW LEVEL AIR MASS. TEMPERATURES NORTH OF WARM FRONT STILL BELOW FREEZING ALONG THE ST. MARY`S RIVER...WITH FOG AND SOME FREEZING DRIZZLE REPORTED. MID LEVEL SHORT WAVE TROUGH MOVING THROUGH EASTERN UPPER AND INTO ONTARIO...SOME DEEPER MOISTURE ASSOCIATED WITH THIS WAVE WITH SOME WEAKER RADAR RETURNS ACROSS UPPER MI. 12Z APX SOUNDING SHOWED MOISTURE EXTENDING UP TO 725MB...AIRCRAFT SOUNDING OUT OF CIU SHOWED MOISTURE ABOVE 650MB. UPSTREAM ON 12Z GRB RAOB MOISTURE ONLY EXTENDED TO AROUND 900MB. WITHIN THE DRIER AIR UPSTREAM CLEARING SKIES HAVE SPREAD ACROSS CENTRAL/SOUTHERN LAKE MICHIGAN...AND HAVE REACHED THE U.S. 31 CORRIDOR UP TO FKS. WILL PROBABLY SEE SOME THINNING OF THE CLOUD COVER ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA (ALONG/SOUTH OF M-72)...EXPECT TO SEE SOME SC POP UP BENEATH INVERSION SO NOT ANTICIPATING A BIG CLEAR OUT INITIALLY. LATER THIS AFTERNOON AS COOLER LOW LEVEL AIR MOVES IN... INVERSION WILL WEAKEN WHICH MAY ALLOW FOR SOME BETTER MIXING OF DRIER AIR INTO THE BOUNDARY LAYER AND POSSIBLY ALLOW FOR SOME MORE SUN. FARTHER NORTH...LOW LEVEL FLOW TURNING MORE WESTERLY SHOULD KEEP CLOUD COVER MORE OR LESS INTACT GIVEN EXTENSIVE LOW CLOUD DECK EXTENDING ACROSS THE UPPER PENINSULA/NORTHWEST WI (ALTHOUGH EVEN SOME OF THIS MAY THIN OUT ESPECIALLY AROUND THE WESTERN/SOUTHERN EDGES OF THE CLOUD DECK). WILL KEEP SOME PATCHY DRIZZLE GOING NORTH OF THE STRAITS THROUGH THE AFTERNOON AS WELL. HAVE BEEN TWEAKING TEMPERATURES ALL MORNING TO TRY AND KEEP UP WITH TEMPORAL TRENDS... AND WILL CONTINUE TO DO SO INTO THE AFTERNOON AS TEMPERATURES CONTINUE TO RISE IN SOME AREAS (E.G., EASTERN UPPER)...OR STEADY OUT AND/OR BEGIN TO COOL A BIT (E.G., NORTHWEST LOWER). JPB && .LONG TERM.../ISSUED AT 400 AM/...TONIGHT AND BEYOND TONIGHT...A RATHER QUIET NIGHT ANTICIPATED...WITH A MORE ROBUST COLD FRONT TO DROP INTO THE REGION THIS EVENING. COMBINATION OF DEEPER SYNOPTIC MOISTURE/BETTER CONVERGENCE RESIDES NORTH OF M-68 IN NRN LOWER...FOR A CHANCE OF/SCATTERED LIGHT SNOW SHOWERS. MARGINAL H8 TEMPS FOR LES DOWNWIND OF LAKE SUPERIOR TO HELP THE SCATTERED LIGHT SNOW SHOWERS IN CHIPPEWA COUNTY. OTHERWISE...H8 TEMPS DO NOT GET COLD ENOUGH FOR ANY LAKE EFFECT. AS THIS FRONT TRAVERSES AREAS SOUTH OF M-68...LOW LEVEL MOISTURE IS EXPECTED TO RAMP UP AGAIN. COULD SEE SCATTERED FLURRIES/CHANCE OF LIGHT SNOW SHOWERS. NOTHING BIG...MAYBE A FEW TENTHS OF SNOW FROM M-68 NORTH. TEMPS WILL FALL INTO THE TEENS NORTH...TO THE MIDDLE 20S SOUTH. SUNDAY THROUGH MONDAY...WILL GO WITH A NO PRECIPITATION FORECAST. MAYBE SOME SORT OF LIGHT LES IN CHIPPEWA COUNTY SUNDAY MORNING...BUT TREND IS FOR WARMING LOW LEVEL TEMPS AGAIN...AS NEXT WARM FRONT AND BAND OF CLOUDS LIFTS INTO THE NORTHWEST GREAT LAKES. HIGH PRESSURE AND DRIER AIR SNAKES INTO THE SRN LAKES...AND THIS AIR MASS WILL GRADUALLY BUILD INTO THE REGION LATE SUNDAY NIGHT AND MONDAY MORNING. THIS WILL LIKELY LEAD TO A SOMEWHAT CHILLY NIGHT...EVEN THOUGH TEMPS ABOVE THE SFC WILL BE WARMING. CAN SEE HIGHS ON SUNDAY IN THE MIDDLE 20S NORTH TO LOWER 30S SOUTH...DROP TO THE SINGLE DIGITS AND TEENS. HIGH LEVEL CLOUDS WILL STREAM INTO THE GTV BAY REGION MONDAY AFTERNOON AHEAD OF NEXT STRONG SHORTWAVE LIFTING INTO THE CENTRAL PLAINS. CONTINUED WARMING WILL LEAD TO HIGHS IN THE 30S. LATER PERIODS...MONDAY NIGHT ONWARD...THE ACTIVE WEATHER PATTERN BEGINS. INITIAL SHORTWAVE AND LOW PRESSURE LIFTS INTO THE UPPER MIDWEST AND WILL THROW WARM/MOIST ADVECTION WITH A BAND OF POTENTIAL RAIN AND FREEZING RAIN AND FOG ACROSS THE NORTH WOODS. CLOUDY/DREARY/FOGGY CONDITIONS ARE EXPECTED INTO TUESDAY. SEVERAL OTHER SHORTWAVES IN THE SRN BRANCH OF THE JET STREAM WILL EJECT INTO THE GREAT LAKES VICINITY IN LATER PERIODS. STILL..THE MORE SIGNIFICANT ONE (AT THIS POINT)...LOOKS TO BRING RAIN...THEN SNOW WEDNESDAY THROUGH THURSDAY. PRECIPITATION MAY BE HEAVY...BUT MANY UNCERTAINTIES EXIST AROUND STORM TRACK AND TIMING. SMD && .AVIATION.../ISSUED AT 648 AM/...VALID FOR 12Z TAFS WARM FRONT LIFTING THROUGH THE GREAT LAKES WITH SURGE OF LOW LEVEL MOISTURE INTO THE REGION HAS RESULTED IN THE DEVELOPMENT OF WIDESPREAD LOW CLOUDS AND FOG. IFR/MVFR CIGS AND VSBYS TO IMPACT MAINLY APN/PLN THIS MORNING. CONDITIONS ARE EXPECTED TO IMPROVE ACROSS TVC BEGINNING 15Z...THEN 18Z AT APN WITH ONSET OF GUSTIER SW WINDS...BUT MVFR CIGS TO HOLD THROUGH THE DAY. COLD FRONT AND SLIGHTLY DRIER LOW LEVEL AIR DROPS ACROSS THE TAF SITES 01-05Z THIS EVENING...BRINGING GUSTY NW WINDS AND LIFTS CIGS A TOUCH WHILE ALSO PROVIDING MAYBE A LIGHT SNOW SHOWER/FLURRY. SMD && .APX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS RALEIGH NC
957 AM EST SAT FEB 7 2009 .SYNOPSIS... HIGH PRESSURE WILL PERSIST OVER THE SOUTHEAST THROUGH THE WEEKEND. MAINLY CLEAR SKIES AND AND MILD TEMPERATURES CAN BE EXPECTED THROUGH SUNDAY. A BACK DOOR COLD FRONT WILL DROP THROUGH THE REGION SUNDAY NIGHT... BRINGING SLIGHTLY COOLER CONDITIONS TO THE AREA FOR MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 955 AM SATURDAY... LATEST SFC ANALYSIS DEPICTS A HIGH PRESSURE CENTER LOCATED OVER SOUTHERN GEORGIA. DEW POINTS ACROSS THE CENTRAL NC WERE IN THE MID 20S WITH SLIGHTLY HIGHER DEW POINTS UPSTREAM IN SC AND ALONG THE NC COAST. A LIGHT SW FLOW HAS DEVELOPED WITH SFC WINDS IN THE 5 TO 8 MPH RANGE. THE LATEST VIS AND IR SAT INDICATE CLEAR SKIES ACROSS THE CAROLINAS WITH JUST A FEW WISPS OF HIGH CLOUDS ACROSS WV AND WESTERN VA. THE 12Z RAOB AT KGSO AND A 1220Z AMADAR AIRCRAFT SOUNDING AT KRDU BOTH INDICATE A TREMENDOUS SFC BASED INVERSION. SFC TEMPS AT BOTH LOCATIONS WERE 34 DEG WITH TEMPS AT THE TOP OF THE INVERSION AT 55 TO 54 DEG F RESPECTIVELY. THIS IS A 21 DEG DELTA T OVER A LAYER JUST 700 FT DEEP AT KGSO. THIS INVERSION HAS ALREADY BEGUN ITS RAPID EROSION. 12Z UPPER AIR ANALYSIS DEPICTS THE WARMEST 1000-850 THICKNESS VALUES EXTENDING SW TO NE WITH COOLER LOW LEVELS ON BOTH SIDES OF THIS THERMAL RIDGE. LOCAL TEMP SCHEME SUGGESTS MAX TEMPS IN THE 63 TO 67 DEG RANGE WHICH REQUIRES ADJUSTING MAX TEMPS UPWARD SLIGHTLY. SKIES REMAIN MAINLY CLEAR TONIGHT. MAIN FORECAST ISSUE REMAINS TEMPS. A WESTERLY FLOW AT 5 TO 10 MPH WILL HELP TO KEEP BOUNDARY LAYER MIXED WITH OVERNIGHT LOWS IN THE UPPER 30S NORTH TO LOWER 40S SOUTHEAST. -BLAES && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 250 AM SATURDAY... SUNNY SKIES WILL BE THE RULE EARLY SUNDAY. CLOUDS WILL BE IN THE INCREASE FROM NORTH TO SOUTH AS HIGH PRESSURE OVER THE NORTH CENTRAL U.S. PUSHES A COLD FRONT THROUGH THE REGION. THE FRONT WILL COME THROUGH THE DRY... SO THE MAIN CONCERN WILL BE HOW THE CLOUD COVER AFFECT TEMPERATURES. HIGHS WILL RANGE FROM THE MID 60S ACROSS THE NORTH TO AROUND 70 ACROSS THE SOUTH. HIGH PRESSURE WILL BUILD DOWN THE ATLANTIC SEABOARD SUNDAY NIGHT INTO MONDAY. LOWS SUNDAY NIGHT IN THE UPPER 30S TO LOWER 40S. A LITTLE COOLER MONDAY WITH THICKNESS VALUES AROUND 1330 WILL YIELD HIGHS IN THE MID TO UPPER 50S NORTH TO LOWER 60S SOUTH. HIGH PRESSURE REMAINS ANCHORED OVER THE NORTHERN AND CENTRAL ATLANTIC COAST MONDAY NIGHT. SOUTHEAST FLOW AT THE SURFACE WILL INCREASE MOISTURE AT THE SURFACE AS INDICATED BY INCREASE IN PWAT VALUES TO AROUND TWO-THIRDS OF AN INCH. VEERING INCREASING LOW LEVEL WINDS WILL ENHANCE CHANCE FOR PRECIP. DUE TO SHALLOW MOIST LAYER WILL LEAVE FORECAST DRY. LOWS WILL RANGE FROM THE UPPER 30S ACROSS THE NORTHEAST TO THE MID 40S IN THE SOUTHWEST. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 3 AM SATURDAY... THE SFC-850 MB HIGH SHIFT OFFSHORE ON TUESDAY...ALLOWING THE FLOW JUST ABOVE THE SFC TO STRENGTHEN TO AROUND 30-35 KT. THIS INDUCES SOME SHALLOW ISENTROPIC LIFT...MAINLY ON THE 295K SFC...AS WARM AIR OVERRIDES THE RELATIVELY COOLER SFC LAYER. WE SHOULD SEE ABUNDANT LOW STRATUS TO START THE DAY...GRADUALLY DECREASING BY AFTERNOON AS THE BOUNDARY LAYER WARMS AND WEAKENS THE ISENTROPIC LIFT. ALTHOUGH THE MODELS STILL TRY TO PRODUCE A HUNDREDTH OF TWO OF PRECIP DURING THE DAY...DO NOT CURRENTLY ANTICIPATE ANY MEASURABLE RAIN. FORECAST SOUNDINGS AND MODEL CROSS SECTIONS SHOW SATURATION NOT OCCURRING ANY HIGHER THAN 850 MB WITH VERY DRY AIR PRESENT ATOP THE SHALLOW SATURATED LAYER. THIS COULD RESULT IN SOME DRIZZLE BUT THAT WOULD BE ABOUT IT. LOW LEVEL THICKNESSES CLIMB TO NEAR 1360M BY 00Z WED...SUGGESTING THAT 70 DEGREE TEMPS COULD BE LURKING. HOWEVER... WITH MOSTLY CLOUDY SKIES TO START THE DAY AND QUESTIONS ON HOW QUICK THE CLOUD COVER WILL DISPERSE MAKES US LEAN TOWARD MAINTAINING LOW TO MID 60S FOR THE TIME BEING. A WELL ABOVE NORMAL NIGHT EXPECTED FOR TUESDAY NIGHT UNDER A SW WIND FLOW. LOWS 45-51. WEDNESDAY WILL VERY LIKELY BE THE WARMEST DAY OF THE WEEK. DEEP LAYER RIDGING WILL PERSIST OVER THE EAST COAST DURING THE DAY. MEANWHILE...A STRONG SHORTWAVE STARTING OUT THE DAY OVER THE SOUTHERN PLAINS WILL APPROACH THE OH/TN VALLEYS BY LATE WEDNESDAY AFTERNOON...DRAMATICALLY INCREASING THE LOW LEVEL SOUTHWESTERLY FLOW. BOTH THE GFS AND ECMWF STRENGTHEN THE 850 MB WINDS TO 45-50 KT BY 00Z THURSDAY WITH GFS FORECAST SOUNDINGS SHOWING MIXING OCCURRING UP TO THIS LEVEL. IF THIS WERE TO OCCUR...THEN A VERY BREEZY TO WINDY DAY WOULD EASILY MATERIALIZE. THIS IS SOMETHING WE WILL MONITOR IN THE COMING DAYS. THE STRONG WARM AIR ADVECTION AHEAD OF THE SHORTWAVE SENDS LOW LEVEL THICKNESSES ALL THE WAY UP TO NEAR 1370M. HAVE NUDGED UP HIGHS A DEGREE OR TWO TO 67 NW TO 72 SE. THE ATTENDANT COLD FRONT TO THE UPPER LEVEL WAVE IS FORECAST TO QUICKLY MOVE THROUGH THE CWA BY 12Z THURSDAY. WILL MAINTAIN A CHANCE OF RAIN ALONG THE FRONT AS ENHANCED UPPER LEVEL DIVERGENCE IN RESPONSE TO THE NEGATIVE TILT OF THE WAVE ALONG WITH EFFICIENT LOW LEVEL MOISTURE TRANSPORT SHOULD BE SUFFICIENT TO MAINTAIN A BAND OF SCATTERED SHOWERS. GIVEN THE FAST MOVEMENT OF THE SYSTEM...RAINFALL TOTALS AT THIS JUNCTURE APPEAR TO BE LIGHT. LOWS 46-51. ALTHOUGH THE FRONT MOVES THROUGH EARLY THURSDAY...STRONG WESTERLY FLOW WILL NEGATE ANY WEAK COLD AIR ADVECTION WITH THICKNESSES HOVERING AROUND 1340M DURING THE DAY THURSDAY. WILL KEEP HIGHS WELL ABOVE NORMAL IN THE LOW TO MID 60S. HIGH PRESSURE FINALLY BUILDS IN FROM THE NORTHWEST ON FRIDAY... HELPING TO COOL TEMPS SOME. STILL EXPECT HIGHS TO BE ABOUT 5-8 DEGREES ABOVE NORMAL (UPPER 50S TO LOWER 60S). && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... AS OF 625 AM SATURDAY... VFR CONDITIONS WITH CLEAR SKIES ARE EXPECTED THROUGH THE FORECAST PERIOD. HIGH PRESSURE WILL PERSIST OFF THE SOUTHEASTERN US COAST... AND EXTEND NW ACROSS NC. THIS WILL MAINTAIN A SW WIND FLOW THROUGH TONIGHT...GENERALLY SUSTAINED IN THE 5-8 KT RANGE...OCCASIONALLY UP TO 10-11 KT DURING THE AFTERNOON. A STRONG NIGHTTIME INVERSION IS FORECAST TO DEVELOP TONIGHT. IN THE LOWEST 1-2 KFT WINDS ARE EXPECTED TO INCREASE TO BETWEEN 35-40 KT...PARTICULARLY OVER RDU/FAY/RWI. THIS SETS UP A STARK CONTRAST BETWEEN THE LIGHTER SW WINDS AT THE SFC (AROUND 5-6 KT) AND THE STRONG WINDS NEAR THE TOP OF THE INVERSION. DUE TO THIS...LOW LEVEL WIND SHEAR HAS BEEN INCLUDED AT RDU/FAY/RWI BEGINNING AT MIDNIGHT. THE FORECAST WINDS IN THE TRIAD ARE CURRENTLY LOWER...CREATING BORDERLINE LLWS CONDITIONS. WILL MONITOR THE NEW GUIDANCE LATER TODAY AND INCLUDE WIND SHEAR IF IT APPEARS MORE LIKELY TO OCCUR. A BACKDOOR FRONT WILL MOVE SOUTHWARD THROUGH CENTRAL NC LATE SUNDAY NIGHT... CAUSING WINDS TO VEER AROUND TO N-NE BUT REMAIN UNDER 12KT. INITIALLY VFR CIGS/VSBYS EXPECTED MONDAY... THEN MVFR OR IFR CONDITIONS ARE POSSIBLE LATE MONDAY NIGHT INTO TUESDAY MORNING... AS THIS HIGH SHIFTS OFFSHORE AND A EAST TO SOUTHEAST OVERRUNNING FLOW DEVELOPS AND BRINGS IN LOW LEVEL MOISTURE. VFR CONDITIONS SHOULD RETURN TUESDAY INTO WEDNESDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES SHORT TERM...RHJ LONG TERM...JFB AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS SALT LAKE CITY UT
850 PM MST SUN FEB 8 2009 .SYNOPSIS...AN UPPER LEVEL LOW PRESSURE SYSTEM ALONG THE ARIZONA BORDER WILL EXIT THROUGH SOUTHEAST UTAH EARLY THIS EVENING. A NEW PACIFIC STORM SYSTEM WILL MOVE THROUGH UTAH EARLY IN THE COMING WEEK...BRINGING COLD AIR AND SIGNIFICANT SNOWFALL TO THE MOUNTAINS. && .DISCUSSION...WATER VAPOR LOOP SHOWS A TROUGH PASSING OVERHEAD...WITH A WEAK RIDGE OVER NEVADA. THE NEXT SYSTEM HAS ALREADY REACHED THE PACIFIC NORTHWEST COAST. ACARS 400-250MB WIND OBSERVATIONS REVEAL THE POSITION OF THE UPPER LEVEL JET AXIS IS OVER WESTERN UTAH AND NORTHERN ARIZONA. 00Z 700MB ANALYSIS PLACED A TROUGH ALONG THE ROCKIES. SLIGHT COOL ADVECTION WAS OCCURRING...WHILE THE COLDEST AIR ON THE ANALYSIS WAS LOCATED ALONG THE PACIFIC NORTHWEST ASSOCIATED WITH THE NEXT SYSTEM. 00Z KSLC RAOB INDICATES SLIGHT COOLING BELOW 700MB AND ABOVE 400MB DURING THE PAST 24 HOURS. THE PRECIPITABLE WATER VALUE HAS RISEN SLIGHTLY TO JUST OVER FOUR TENTHS OF AN INCH. COLD CONVEYOR CONTINUES TO WRAP AROUND NORTHERN UTAH AS THE MID LEVEL SYSTEM TRANSLATES OVERHEAD. THIS HAS RESULTED IN LIGHT VALLEY RAIN AND MOUNTAIN SNOW...AS GUSTY SOUTHWEST WINDS DEVELOPED ACROSS WEST CENTRAL AND SOUTHWEST UTAH WITH THE PASSAGE OF THE TROUGH. PRESSURE RISES HAVE BEEN MINIMAL...ON THE ORDER OF 1 TO 2MB/3HR. WOULD NORMALLY EXPECT THIS PRECIPITATION TO DIMINISH WITH THE PASSAGE OF THE TROUGH AND RIDGING BUILDING IN ALOFT. HOWEVER...THE THERMAL PROFILES WILL BE MODIFIED MORE SIGNIFICANTLY BY THE APPROACH OF THE NEXT SYSTEM OVERNIGHT...AND THUS EXPECT PRECIPITATION TO LINGER OVERNIGHT BEFORE ENHANCING EARLY MONDAY. MEANWHILE...RUC INDICATES THAT THE LIFTED INDEX IS WANING ACROSS CENTRAL AND SOUTHERN UTAH WITH THE LOSS OF DAYTIME HEATING. THIS IN CONJUNCTION WITH THE PASSAGE OF THE TROUGH AND INCREASING DRY SOUTHWEST FLOW SHOULD CAUSE PRECIPITATION TO BE SPOTTY OVERNIGHT UNTIL THE NEXT SYSTEM APPROACHES EARLY TOMORROW MORNING. UPDATED TO REMOVE EVENING REFERENCES AND TWEAK TEMPERATURES BASED ON CURRENT TRENDS. PREVIOUS DISCUSSION FOLLOWS... THE NEXT PACIFIC TROUGH TO AFFECT THE GREAT BASIN HAS REACHED THE PACIFIC NW COAST THIS AFTERNOON. THIS FEATURE WILL SPLIT AS IT MOVES INLAND...TAKING THE BULK OF THE COLD AIR THROUGH THE WRN THEN SRN PORTIONS OF THE BASIN. MODEL SOUNDINGS GENERALLY AGREE THAT THE AIRMASS ACROSS THE FORECAST AREA WILL BE MOIST AND CONDITIONALLY UNSTABLE AFTER THE COLD AIR MOVES INTO THE AREA MONDAY. ADEQUATE DYNAMIC LIFT WORKING ON THIS AIRMASS ALONG WITH OROGRAPHIC LIFT SHOULD LEAD TO SIGNIFICANT SNOWFALL OVER THE NRN MOUNTAINS. EXPECTED AMOUNTS BORDER ON ADVISORY-HEAVY SNOW CRITERIA. HAVE OPTED FOR AN ADVISORY LATE TONIGHT THROUGH TUESDAY MORNING...THOUGH WOULD NOT BE SURPRISED IF LOCAL AREAS OF THE WASATCH RANGE REPORT GREATER AMOUNTS. SHORTWAVE RIDGING TUESDAY NIGHT/EARLY WEDNESDAY WILL BE FOLLOWED BY THE NEXT IN A SERIES OF ERN PACIFIC TROUGHS DIGGING SE FROM THE GULF OF ALASKA. THESE SUBSEQUENT TROUGHS WILL LOSE SOME OF THEIR PUNCH AS THEY MOVE INLAND...THEN SE THROUGH THE WRN/SRN GREAT BASIN. STILL...WITH THIS MOISTURE ALREADY IN PLACE...ANY SYSTEM WITH EVEN WEAK BAROCLINIC STRUCTURE SHOULD BE ABLE GENERATE PRECIP OVER THE FORECAST AREA. WILL KEEP PRECIP IN THE FORECAST THROUGH MUCH OF THE EXTENDED FORECAST PERIOD. && .AVIATION...CEILINGS WILL OSCILLATE BETWEEN 2500 FT AGL AND 5000 FT AGL AT THE SLC TERMINAL DUE TO LIGHT RAIN SHOWERS THROUGH 07Z. AS THE TEMPERATURES ALOFT COOL A CHANGE OVER TO SNOW IS EXPECTED BETWEEN 07Z AND 09Z. THERE IS A 30 PERCENT CHANCE THAT THIS CHANGE OVER WILL NOT OCCUR UNTIL AFTER 09Z. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO NOON TUESDAY FOR UTZ007-UTZ008-UTZ009. WY...NONE. && $$ PUBLIC...ROGOWSKI/CONGER AVIATION...STRUTHWOLF FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT... HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS HONOLULU HI
1000 AM HST SUN FEB 8 2009 .SYNOPSIS... A RIDGE TO THE NORTH OF THE STATE WILL RESULT IN MODERATE TRADES TODAY THROUGH MOST OF MONDAY. A WEAK TROUGH IS EXPECTED TO DEVELOP JUST NORTH OF THE ISLANDS MONDAY INTO TUESDAY...WITH THE TRADES GRADUALLY WEAKENING AND BECOMING MORE SOUTHEASTERLY. THIS TROUGH WILL MOVE WEST OF THE AREA WEDNESDAY AND THURSDAY...ALLOWING THE TRADES TO INCREASE FOR THE REST OF THE WORK WEEK. A STRONG RIDGE WILL BUILD WELL NORTH OF THE AREA BY THE END OF THE WEEK RESULTING IN STRONG TRADES OVER THE ISLANDS. && .DISCUSSION... AN UPPER LEVEL TROUGH AXIS REMAINS POSITIONED ACROSS THE STATE TODAY. ALTHOUGH THERE ARE NO WELL DEFINED SHORT WAVES IN THE WATER VAPOR LOOP OVER THE STATE...THERE ARE SHORT WAVES POSITIONED ABOUT 250 MILES NORTH OF OAHU AND 300 MILES SOUTHWEST OF THE BIG ISLAND. THESE SHORT WAVES APPEAR TO BE ROTATING VERY SLOWLY AROUND THE MAIN TROUGH AND ARE RESULTING IN TWO DISTINCT AREAS OF DEEP CONVECTION ON EITHER SIDE OF THE STATE. IN THE LOW LEVELS...MODERATE TRADES HAVE DEVELOPED ACROSS THE ISLANDS. SO THE ISLANDS APPEAR TO BE IN AN AREA THAT LACKS ANY LARGE SCALE ASCENT...LEADING TO BENIGN TRADE WIND WEATHER. SCATTERED SHOWERS ARE OBSERVED ON THE WINDWARD SIDES OF THE ISLANDS...WITH RAINFALL AMOUNTS LESS THAN .50 OF AN INCH. THE AIRMASS REMAINS UNSTABLE EARLIER THIS MORNING WITH PLENTY OF CAPE ON LIHUE AND HILO SOUNDINGS. NO CAPPING INVERSION IS NOTED ON THE 12Z RAOBS...HOWEVER 18Z AMDAR DATA FROM HNL INDICATES SOME WEAK LOW LEVEL STABILITY AROUND 5000 FEET DEVELOPING. THIS COMBINED WITH WEAK SYNOPTICS WILL BE ENOUGH TO KEEP MOST SHOWERS ON THE LIGHT SIDE TODAY...BUT STILL CANNOT RULE OUT THE POSSIBILITY OF A STRAY THUNDERSTORM AS THE LAYER REMAINS MOIST AND TEMPERATURES ALOFT ON THE COLD SIDE...-14 AT 500 MB. APPEARS THAT THE MOST LIKELY PLACE FOR A THUNDERSTORM WOULD BE THE BIG ISLAND SLOPES THIS AFTERNOON. FOR THE FIRST HALF OF THE WORK WEEK...A WEAK LOW LEVEL TROUGH DEVELOPS IN THE VICINITY OF THE ISLANDS WHICH WILL BRING AN UPTICK IN THE SHOWER ACTIVITY. LIGHT TO MODERATE TRADES CONTINUE INTO MONDAY...SO LEEWARD SHOWERS WILL BE ISOLATED AT BEST. THE TROUGH STICKS AROUND THE AREA TUESDAY WITH TRADES BECOMING LIGHT AND BECOMING MORE SOUTHEASTERLY. THIS WILL BRING INTO PLAY THE POSSIBILITY FOR MORE AFTERNOON LEEWARD SHOWER ACTIVITY. GFS AND ECMWF GUIDANCE CONTINUES TO BUILD A STRONG 1036+ MB RIDGE TO THE NORTH OF OUR AREA FOR THE END OF THE WEEK. THIS RIDGE PARKS TO THE NORTH OF THE STATE BRINGING A PERIOD OF STRONG TRADES LASTING INTO THE COMING WEEKEND. && .MARINE... EXPECTED STRONG TRADE WINDS ACROSS THE EAST CENTRAL PACIFIC TOWARDS THE END OF THE WEEK WILL BRING LARGE AND ROUGH SURF...POTENTIALLY WELL ABOVE THE 8 FOOT ADVISORY LEVEL TO THE EAST FACING SHORES. HAVE EXPANDED THE EXISTING SMALL CRAFT ADVISORY FOR MAALAEA BAY...ALENUIHAHA CHANNEL AND WATERS SOUTH AND SOUTHWEST OF SOUTH POINT TO INCLUDE THE PAILOLO CHANNEL AS THE TERRAIN ACCELERATED TRADE WINDS HAVE REACHED 25 KNOTS THERE. && .HFO WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY UNTIL 6 AM HST MONDAY FOR PAILOLO CHANNEL- MAALAEA BAY-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS. && $$ BRENCHLEY
SEE PREVIOUS FORECAST DISCUSSION.

AVIATION... FOR THE 00Z TAFS...BIGGEST CHALLENGE IN THE TAFS IS TIMING FLIGHT RESTRICTION CIGS. MODELS FAIRLY CONSISTENT IN BRINGING DEEPER LOW LEVEL MOISTURE OVER TAF SITES AFTER MIDNIGHT TONIGHT...HOWEVER UPSTREAM THE DEEPER LOW LEVEL MOISTURE IS NOT CURRENTLY ASSOCIATED WITH LOW LEVEL STRATUS SO THINK THE MODELS MAY BE TOO AGGRESSIVE BRINGING CIGS DOWN INTO MVFR/IFR RANGE TONIGHT. BACKED OFF A FEW HOURS ON TIMING OF MVFR CIGS AND ADDED IN SO IFR CIGS WHEN MAIN STORM SYSTEM PULLS OUT OVER EASTERN KS TOMORROW MORNING. LOW LEVEL CIGS EXPECTED TO BE SCOURED OUT BY MONDAY AFTERNOON AS A FRONTAL BOUNDARY MOVES THROUGH. WINDS EXPECTED TO REMAIN VERY STRONG FOR LIGHT AIRCRAFT ON MONDAY WITH SOUTHERLY WINDS GUSTING ABOVE 40 MPH AT TIMES. CAVANAUGH PREV DISCUSSION... /ISSUED 315 PM CST SUN FEB 8 2009/ DISCUSSION... PRECIPITATION CHANCES AND WINDS ARE THE MAIN CONCERNS FOR THE TONIGHT AND MONDAY PORTION OF THE FORECAST. MORNING UPPER AIR OBSERVATIONS INCLUDED A 120KT JET STREAK SAMPLED BY AIRCRAFT IN WESTERN MEXICO ON THE SSE PORTION OF AN UPPER LOW OVER THE SOUTHWEST CONUS. TUS REPORTED A 100M 500MB HEIGHT FALL AS THIS SYSTEM MOVES EAST TOWARD THE ROCKIES. 850MB MAP AGAIN SHOWED RATHER WARM TEMPS FOR MUCH OF THE AREA FOR EARLY FEBRUARY ALONG WITH 7-10C DEWPOINTS FROM SGF AND DDC ON SOUTH. 20Z SURFACE DATA SUGGESTS WARM FRONT IN SOUTHERN KANSAS WITH TEMPS APPROACHING 70F....WITH LOW TO MID 40S HOLDING IN FAR NORTHEAST KANSAS. 3-HOUR PRESSURE FALLS WERE IN THE 4-5MB RANGE...SOME 2-3MB ABOVE NORMAL. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE SOUTHWEST UPPER TROF SURGING NORTHEAST INTO THE NORTHERN PLAINS WHILE DEEPENING AND BECOMING TONIGHT INTO MONDAY AFTERNOON. ISENTROPIC LIFT LOCALLY IS NOT VERY STRONG...AND MID LEVEL MOISTURE IS RATHER LACKING THROUGH THE LATE NIGHT UNTIL THE STRONGER Q-G FORCING MOVES IN...AND HAVE RESULTANTLY DROPPED POPS A BIT FOR CENTRAL AND EASTERN AREAS FOR TONIGHT. INSTABILITY IS NOT VERY IMPRESSIVE...BIT WILL MAINTAIN THUNDER MENTION. BEST FORCING MAY SPLIT THE CWA SO WILL KEEP SOME DOUBT IN EVERYONE GETTING WET LATE TONIGHT INTO MONDAY MORNING. INCREASING AND VEERING LOW LEVEL WINDS RESPONDING TO CYCLOGENESIS TO THE WEST WILL PUSH THE WARM FRONT NORTH THROUGH THE CWA...AND SHOULD KEEP TEMPS RATHER WARM. PRESSURE GRADIENT BY DAWN APPROACHES 8MB ACROSS THE CWA...BUT BACKED NATURE OF WINDS AND LIMITED MIXING DEPTHS SHOULD KEEP SPEEDS BELOW ADVISORY LEVELS. AS THE SYSTEM PUSHES NORTHEAST...WINDS WILL CONTINUE TO BACK AND BECOME MORE UNIDIRECTIONAL FOR INCREASED WIND POTENTIAL...ESPECIALLY IN THE AFTERNOON. MIXING DEPTHS MAY REACH INTO THE 55KT WINDS AROUND 800MB...SO AN ADVISORY SEEMS IN ORDER. WITH SOME LOW LEVEL MOISTURE REMAINING...WILL NEED TO WATCH FOR ADDITIONAL THUNDER DEVELOPMENT FOR THE AFTERNOON...THOUGH LIMITED INSTABILITY SHOULD KEEP MUCH IF ANY SEVERE CONVECTION IN CHECK. DIDNT ALTER TEMPS MUCH. 65 NEXT SHORTWAVE ON TRACK TO MOVE ACROSS THE FORECAST AREA TUESDAY NIGHT AND EARLY WEDNESDAY. THE GFS APPEARS TO BE AN OUTLIER WITH PROBLEMS ARISING FROM CONVECTIVE FEEDBACK TUESDAY AFTERNOON. THEREFORE USED THE NAM/UKMET/ECMWF WHICH ARE SIMILAR IN THE TRACK AND STRENGTH OF THE SFC LOW ACROSS NORTHEAST OK AND SOUTHEAST KS. MODELS SHOW STRONG QG FORCING WITH THE DEVELOPMENT OF A TROWAL FEATURE TO THE NORTHWEST OF THE SFC LOW MOVING ACROSS THE FORECAST AREA BETWEEN 06Z AND 18Z WEDNESDAY. NAM FORECAST SOUNDINGS KEEP SFC TEMPS GENERALLY AROUND 40 TUESDAY NIGHT WITHIN THE AXIS OF HEAVIER PRECIP INDICATING THAT MOST OF THE PRECIP WILL REMAIN LIQUID. BUT THIS WILL NEED TO BE MONITORED AS A COUPLE DEGREES COOLER COULD MEAN A DECENT BAND OF SNOW ACROSS PARTS OF THE AREA. INITIALLY MID LEVEL LAPSE RATES ARE STEEP ENOUGH TO CONTINUE MENTION OF THUNDER TUESDAY NIGHT. FORECAST SOUNDINGS SHOW THIS POTENTIAL INSTABILITY DIMINISHING AS THE COLUMN BECOMES SATURATED BY 12Z WEDNESDAY. WAA AND MOSTLY SUNNY SKIES SHOULD ALLOW TEMPS TO WARM WELL ABOVE NORMAL FOR TUESDAY. WITH MODELS NOT OVERLY AGGRESSIVE WITH COLD AIR ON THE BACK SIDE AND SOME CLEARING WEDNESDAY AFTERNOON...THINK TEMPS WILL RECOVER INTO THE MID AND UPPER 40S FOR WEDNESDAY. EXPECT A BREAK FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT BEFORE THE NEXT SHORTWAVE BEGINS TO MOVE OUT INTO THE PLAINS. MODEL CONSISTENCY WITH THIS WAVE HAS SHOWN SOME UNCERTAINTY WITH THE TRACK OF THE SYSTEM. NEVERTHELESS LOOKS LIKE NEXT CHANCE FOR PRECIP WITH BE FRIDAY AND FRIDAY NIGHT. CONSIDERED REMOVING POPS FORM SATURDAY WITH THE ECMWF SHOWING SHORTWAVE RIDGING...BUT CONFIDENCE IN TIMING THESE SMALL SCALE FEATURES IS NOT HIGH ENOUGH. TEMP FORECAST FOR FRIDAY AND FRIDAY NIGHT IS RATHER CONSERVATIVE SO CONTINUED WITH A RAIN/SNOW FORECAST FRIDAY CHANGING TO SNOW FRIDAY NIGHT. MEDIUM RANGE MODELS ARE SHOWING ANOTHER WAVE MOVING OUT FROM THE ROCKIES ON SUNDAY. GIVEN THE ACTIVE PATTERN WENT AHEAD AND INSERTED SLIGHT CHANCE POOPS FOR SUNDAY...THOUGH THE 12Z ECMWF IS NOT NEARLY AS STRONG WITH THIS FOURTH WAVE AS THE PREVIOUS. CONFIDENCE IS LOW GIVEN POOR CONSISTENCY WITH THE GFS. STAYED CLOSE TO HPC AND CLIMO FOR TEMPS TO END THE FORECAST PERIOD. WOLTERS && .TOP WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY FROM 9 AM MONDAY TO 6 PM MONDAY FOR KSZ008-KSZ009- KSZ010-KSZ011-KSZ012-KSZ020-KSZ021-KSZ022-KSZ023-KSZ024-KSZ026- KSZ034-KSZ035-KSZ036-KSZ037-KSZ038-KSZ039-KSZ040-KSZ054-KSZ055- KSZ056-KSZ058-KSZ059. && $$
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
213 AM CST MON FEB 9 2009 .DISCUSSION... VERY COMPLEX WEATHER SCENARIO DEVELOPING ACROSS THE UPPER MIDWEST AS DEEP MOISTURE SURGES NORTHWARD WITH SURFACE TEMPERATURES NEAR THE FREEZING MARK. RECENT RADAR RETURNS AS OF 130 AM...HAD MOST OF THE MEASURABLE PRECIPITATION IN THE FORM OF RAIN ACROSS THE DAKOTAS AND NORTHWEST MINNESOTA WHERE BETTER DYNAMICS ASSOCIATED WITH 55KT LOW LEVEL JET HAD OCCURRED. ALTHOUGH MOST AREAS HAVE SURFACE TEMPERATURES IN THE LOW TO MID 30S...FAR NORTHWEST MINNESOTA DID INDICATE SUBSTANTIAL SUB FREEZING TEMPERATURES. IN ADDITION...RUC13 AND EVEN SOME OF ACARS DATA EARLIER TONIGHT HAS A PRONOUNCED ELEVATED WARM LAYER WITH 85H TEMPS NEAR 10C. RUC13 ALSO IS ADVERTISING WET BULB TEMPERATURES ABOVE 0C EXCEPT IN WESTERN WISCONSIN AND EAST CENTRAL MINNESOTA WHERE PRECIPITATION HASN`T STARTED YET. MAIN FORECAST CONCERN THIS MORNING WILL BE THE FREEZING RAIN ADVISORY AND IF THIS CAN BE CANCELED OR AT LEAST TRIMMED BACK TO ONLY THE FAR NORTHERN CWA. WILL MAKE LAST MINUTE CALL OF THIS SCENARIO BUT ALL INDICATIONS IS TO CANCEL THE ADVISORY BEFORE 6 AM. ALTHOUGH PRECIPITATION IS A GOOD BIT TODAY AS WARM AIR ADVECTION/MOISTURE WILL SATURATE THE ATMOSPHERE BY LATER THIS MORNING...THERE ARE SOME CONCERNS WITH THE ALREADY DRY AIRMASS ACROSS THE EASTERN CWA ALLOWING FOR MOSTLY SCATTERED OR ISOLATED PRECIPITATION THIS MORNING. HIGHLY EFFICIENT PRECIPITATION PRODUCING CLOUDS WILL LIKELY HOLD OFF UNTIL LATER THIS AFTERNOON AS THE MAIN UPPER LOW MOVES ACROSS THE AREA. IN ADDITION...ELEVATED INSTABILITY OF 250/400 J/KG ASSOCIATED WITH THIS FEATURE...WILL ENHANCE THE CONVECTIVE POTENTIAL AND ALLOW FOR ISOLATED THUNDERSTORMS TO DEVELOP. QPF AMOUNTS WILL LIKELY BE LOW DUE TO THIS TIME OF YEAR...BUT INCREDIBLE PRECIPITABLE WATER VALUES OF 200/300% ABOVE NORMAL AND THE CHANCE OF CONVECTION WILL LEAD TO ISOLATED HEAVY RAINFALL AND THE POSSIBILITY OF LOCALIZED FLOODING WHERE AREAS OF POOR DRAINAGE AND SNOW COVER EXISTS. ONCE THIS MAIN WAVE MOVES ACROSS THE AREA...MOST OF THE STEADIER PRECIPITATION WILL BE CONCENTRATED NEAR THE UPPER LOW WHERE IT IS PROGGED TO SLOWLY MOVE ACROSS WESTERN MINNESOTA AND INTO NORTHERN MINNESOTA BY TUESDAY AFTERNOON. THUS...PRECIPITATION CHANCES WILL INCREASE FURTHER NORTHWEST ACROSS OUR CWA. IN ADDITION...THERMODYNAMIC PROFILES INDICATE THAT COLDER AIR WRAPPING AROUND THIS UPPER LOW...WILL FINALLY ALLOW FOR SNOW TO MIX IN...ESPECIALLY ACROSS WESTERN MINNESOTA AFTER MIDNIGHT. THE PRECIPITATION SHOULD SLOWLY END ACROSS CENTRAL MINNESOTA ON TUESDAY WITH SOME LIGHT SNOW POSSIBLE ON WEDNESDAY AS ANOTHER UNORGANIZED DISTURBANCE MOVES ACROSS THE REGION. QPF AMOUNTS WILL REMAIN LOW ENOUGH FOR TRACE SNOWFALL AMOUNTS OR UNDER AN INCH. NO CHANGES IN THE EXTENDED OUTLOOK AS MODELS CONTINUE THE TREND OF MOST OF THE ACTIVE WEATHER REMAINING SOUTH OF THE FORECAST AREA. && .AVIATION.../06Z TAF ISSUANCE/ THE IMMEDIATE TAF CONCERN IS THE POTENTIAL FOR A PERIOD OF -FZRA ACROSS WEST/NORTH CENTRAL MN TAF SITES OVERNIGHT. CURRENTLY SEE WARM AIR ADVECTION BAND OF PRECIPITATION DEVELOPING ACROSS THE DAKOTAS. EXPECT THE LOW LEVELS TO ADEQUATELY SATURATE ACROSS WEST/NORTH CENTRAL MN EARLY IN THE TAF PERIOD...AND SUBSEQUENTLY ALLOW LIGHT PRECIPITATION TO ENSUE AT WESTERN TAF SITES. EXPECT THE PRECIP TYPE TO BE -FZRA OR -FZDZ AT KAXN/KRWF/KSTC UNTIL AROUND 14Z...WHEN TEMPERATURES SHOULD THEN BE WARM ENOUGH TO YIELD LIQUID PRECIP. CIGS ASSOCIATED WITH THE WAA BAND HAVE INTIALLY BEEN OF THE VFR VARIETY...BUT EXPECT GRADUAL DETORIORATION OVERNIGHT. SINCE PRECIP WILL LIKELY NOT BEGIN UNTIL MID/LATE MORNING AT KMSP/KRNH/EAU...TEMPERATURES WILL LIKELY BE WARM ENOUGH TO PROHIBIT THEM FROM RECEIVING FREEZING PRECIP. AFTER THE ADVECTION BAND OF PRECIP LIFTS NORTH/EAST...WILL LIKELY SEE A LULL IN PRECIPITATION UNTIL THE MAIN LOW AND WARM FRONT LIFTS ACROSS THE AREA. THIS WILL BE TOUGH TO TIME...BUT MORE ORGANIZED/WIDESPREAD PRECIP SHOULD EXPAND NORTH/EAST ACROSS THE AREA BETWEEN 20Z AND 02Z. PREDOMINATE CIGS WILL LIKELY DECLINE INTO THE IFR CATEGORY AS THE WARM FRONT DRAWS NEAR...ALONG WITH IFR VISBILITIES AND LIFR CIGS WHEN RAIN IS OCCURRING. THERE WILL ALSO BE A TIMEFRAME WHEN ISOLATED THUNDER MAY OCCUR...MAINLY AT KMSP/KRNH/KEAU DURING THE AFTERNOON AND EVENING HOURS. ANOTHER CONCERN WILL BE LOW LEVEL WIND SHEAR THROUGH MOST OF THE DAY...WITH PROGGED 0-1KM SHEAR MAGNITUDES BETWEEN 45 AND 50 KNOTS. MAY SEEM SOME IMPROVEMENT IN THE CEILINGS AFTER 03Z TUESDAY AS THE DRY SLOT BEGINS WORKING INTO THE AREA. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...FREEZING RAIN ADVISORY FROM 6 AM THIS MORNING TO NOON CST TODAY FOR BENTON-CHISAGO-ISANTI-KANABEC-MILLE LACS-MORRISON- SHERBURNE. FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR DOUGLAS-POPE- STEARNS-STEVENS-TODD. WI...NONE. && $$ JLT/LS
AREA FORECAST DISCUSSION
NWS TOPEKA KS
635 AM CST MON FEB 9 2009 .UPDATE... UPDATE FOR THE 12Z TAFS. && .DISCUSSION... SEE PREVIOUS DISCUSSION. && .AVIATION... SHOWERS WERE EXPANDING IN COVERAGE ACRS CNTRL KS AS OF 12Z AND THIS IS EXPECTED TO MOV INTO THE TAF SITES BY 14Z AND CONT THRU ABOUT 18Z. WE EXPECTED MVF VISBY WITH THE SHOWERS...BUT MAY SEE SOME IFR CEILINGS FRM ARND 14Z THRU 18Z TODAY. THERE AFTR...MID LVL DRY SLOP MOVS INTO THE TAF SITES AND WE SHLD SEE CLDS CLR. MAY CONT TO SEE A SCT CU DECK AT TOP/FOE IN THE DEEPER MOISTURE. WINDS WL INCREASE THIS AFTN WITH GUSTS ARND 40 KTS EXPECTED BY PEAK HEATING. VFR CONDS EXPECTED TO CONT THRU THE NIGHT AND WINDS WILL BEGIN TO DIMINISH THIS EVNG AND WE SEE THE GUSTS END BY 10Z TUE. && .PREV DISCUSSION... /ISSUED 420 AM CST MON FEB 9 2009/ DISCUSSION... LATEST WATER VAPOR SHOWING STRONG SHORTWAVE MOVING WESTERN TX WITH ANOTHER SHORTWAVE LOBE ACROSS EASTERN NM. AT THE SFC...LOW PRESSURE CONTINUES TO DEVELOP OVER NORTHEAST CO AND WILL LIFT NORTHEAST THROUGH THE DAY. AS THE SHORTWAVE(S) LIFT NORTHEAST ACROSS KS... INITIAL AREA OF SHOWERS AND SOME EMBEDDED THUNDER WILL LIFT NORTHEAST ACROSS THE CWA AND ENDING BY LATE MORNING. WILL KEEP CATEGORICAL POPS STRENGTHENING PRESSURE GRADIENT WILL BE SITUATED ACROSS THE CWA AS DRY SLOT BEGINS TO APPROACH THE SOUTHWEST CWA TOWARDS 18Z. THE EASTERN NM WAVE WILL BEGIN TO TRAVERSE THE CWA SOUTHWEST TO NORTHEAST FROM 18Z THROUGH 21Z. DURING THE THIS TIMEFRAME...THE CWA...ESPECIALLY THE NORTHEAST HALF OF THE CWA... WILL BEGIN TO EXPERIENCE STEEPER LAPSE RATES AS LOW LEVEL MOISTURE AXIS COINCIDES WITH THE PASSAGE OF THE UPPER TROUGH AXIS AND A BRIEF WINDOW OF LARGE SCALE ASCENT. WITH STRONG SHEAR...FAVORABLE HODOGRAPHS AND CAPES OF 500-800 J/KG...COULD SEE A FEW LOW TOPPED SUPERCELLS DEVELOP IN THIS TIMEFRAME CAPABLE OF STRONG WINDS AND POSSIBLY A BRIEF TORNADO...WHICH WOULD RAPIDLY MOVE NORTHEAST OF THE CWA BY LATE AFTERNOON AS DRY SLOT MOVES IN. DURING THIS TIMEFRAME...SHOULD ALSO SEE THE STRONGEST MOMENTUM TRANSFER OF WINDS AS FCST SOUNDINGS STILL SUGGEST NEARLY ADIABATIC LAPSE RATES WITHIN THE DRY SLOT WITHIN INCREASINGLY UNIDIRECTIONAL FLOW. WILL MAINTAIN WIND ADVISORY ALL AREAS 9 AM THIS MORNING UNTIL 6 PM TONIGHT...HOWEVER THE 1 PM TO 4 PM TIMEFRAME LOOKS MOST IMPRESSIVE...ESPECIALLY ALONG THE TURNPIKE CORRIDOR WHEN SUSTAINED 30 TO 35 MPH WITH GUSTS OF 45 TO 55 MPH ARE POSSIBLE. IF DRY SLOT MOVES IN QUICKER THAN EXPECTED...THEN WINDS SPEEDS WILL BE EVEN STRONGER AND DAY SHIFT MAY NEED TO CONSIDER A HIGH WIND WARNING IN SOME AREAS IF THIS OCCURS. HAVE INCREASED HIGHS MOST AREAS TODAY INTO THE MIDDLE 60S. TONIGHT...SKIES WILL CLEAR ALL AREAS WITH DECREASING WINDS. DRIER AIR WILL PUSH SOUTH AND EAST...BUT NOT TOO FAR TO THE SOUTH OF THE CWA. STRONG SHORTWAVE...NOW MOVING INTO THE CA COAST WILL MOVE RAPIDLY EAST INTO THE SOUTHERN HIGH PLAINS LATE IN THE DAY AND SHOULD INDUCE CYCLOGENESIS WHICH WILL ALLOW FOR A RETURN FLOW OF THE MOISTURE THAT WAS POOLED TO THE SOUTH TO MOVE NORTHWARD IN THE DEVELOPING LLVL JET TUESDAY EVENING. THIS WILL RESULT IN INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS...MAINLY ACROSS THE SOUTHEAST HALF OF THE CWA TUESDAY NIGHT WITH RAIN...POSSIBLY MIXED WITH OR CHANGING TO SNOW AFTER MIDNIGHT NORTHWEST AREAS. AS THE SYSTEM DEEPENS OVER THE SOUTHERN PLAINS...THIS PRECIP COULD LINGER ACROSS THE CWA THE FIRST HALF OF THE DAY WEDNESDAY BEFORE MOVING RAPIDLY OFF TO THE EAST. WITH UPPER SYSTEM UNDERGOING RAPID STRENGTHENING...A CONCERN FOR A POSSIBLE RAPID CHANGEOVER TO SNOW...BUT IS STILL TOO FAR OUT TO FCST WITH HIGH CONFIDENCE AND WILL KEEP AS RAIN OR SNOW FOR NOW. NEXT SYSTEM STILL FCST TO ARRIVE WITH ANOTHER RAIN SNOW CHANCE BY THE END OF THE WEEK AS ACTIVE FLOW PATTERN CONTINUES. THIS IS WELL HANDLED WITH THE CURRENT FCST AND NO CHANGES MADE TO THE FCST BEYOND WEDNESDAY. AVIATION... FOR THE 06Z TAFS...BACKED OFF TIMING OF THE MVFR CIGS EVEN FURTHER AS LOW LEVEL EASTERLY FLOW HAS KEPT MVFR CIGS WELL OFF TO THE SOUTH AND EAST OF TAF SITES. INTRODUCED SOME LLWS INTO THE TAFS AS EASTERLY FLOW REMAINS DECOUPLED FROM THE INCREASING STRENGTH OF THE SOUTHERLY LOW LEVEL JET TONIGHT. KEPT IFR CIGS IN THE FORECAST AS LOW LEVEL SATURATION LOOKS LIKELY ONCE THE UPPER LEVEL SYSTEM PULLS INTO THE CENTRAL PLAINS THIS MORNING. LOW LEVEL WINDS LOOK TO REMAIN STRONG ON MONDAY...ESPECIALLY FOR LIGHT AIRCRAFT. CAVANAUGH && .TOP WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 6 PM MONDAY FOR KSZ008-KSZ009-KSZ010-KSZ011- KSZ012-KSZ020-KSZ021-KSZ022-KSZ023-KSZ024-KSZ026-KSZ034-KSZ035- KSZ036-KSZ037-KSZ038-KSZ039-KSZ040-KSZ054-KSZ055-KSZ056-KSZ058- KSZ059. && $$ BOUSTEAD
AREA FORECAST DISCUSSION
NWS TOPEKA KS
420 AM CST MON FEB 9 2009 .DISCUSSION... LATEST WATER VAPOR SHOWING STRONG SHORTWAVE MOVING WESTERN TX WITH ANOTHER SHORTWAVE LOBE ACROSS EASTERN NM. AT THE SFC...LOW PRESSURE CONTINUES TO DEVELOP OVER NORTHEAST CO AND WILL LIFT NORTHEAST THROUGH THE DAY. AS THE SHORTWAVE(S) LIFT NORTHEAST ACROSS KS... INITIAL AREA OF SHOWERS AND SOME EMBEDDED THUNDER WILL LIFT NORTHEAST ACROSS THE CWA AND ENDING BY LATE MORNING. WILL KEEP CATEGORICAL POPS STRENGTHENING PRESSURE GRADIENT WILL BE SITUATED ACROSS THE CWA AS DRY SLOT BEGINS TO APPROACH THE SOUTHWEST CWA TOWARDS 18Z. THE EASTERN NM WAVE WILL BEGIN TO TRAVERSE THE CWA SOUTHWEST TO NORTHEAST FROM 18Z THROUGH 21Z. DURING THE THIS TIMEFRAME...THE CWA...ESPECIALLY THE NORTHEAST HALF OF THE CWA... WILL BEGIN TO EXPERIENCE STEEPER LAPSE RATES AS LOW LEVEL MOISTURE AXIS COINCIDES WITH THE PASSAGE OF THE UPPER TROUGH AXIS AND A BRIEF WINDOW OF LARGE SCALE ASCENT. WITH STRONG SHEAR...FAVORABLE HODOGRAPHS AND CAPES OF 500-800 J/KG...COULD SEE A FEW LOW TOPPED SUPERCELLS DEVELOP IN THIS TIMEFRAME CAPABLE OF STRONG WINDS AND POSSIBLY A BRIEF TORNADO...WHICH WOULD RAPIDLY MOVE NORTHEAST OF THE CWA BY LATE AFTERNOON AS DRY SLOT MOVES IN. DURING THIS TIMEFRAME...SHOULD ALSO SEE THE STRONGEST MOMENTUM TRANSFER OF WINDS AS FCST SOUNDINGS STILL SUGGEST NEARLY ADIABATIC LAPSE RATES WITHIN THE DRY SLOT WITHIN INCREASINGLY UNIDIRECTIONAL FLOW. WILL MAINTAIN WIND ADVISORY ALL AREAS 9 AM THIS MORNING UNTIL 6 PM TONIGHT...HOWEVER THE 1 PM TO 4 PM TIMEFRAME LOOKS MOST IMPRESSIVE...ESPECIALLY ALONG THE TURNPIKE CORRIDOR WHEN SUSTAINED 30 TO 35 MPH WITH GUSTS OF 45 TO 55 MPH ARE POSSIBLE. IF DRY SLOT MOVES IN QUICKER THAN EXPECTED...THEN WINDS SPEEDS WILL BE EVEN STRONGER AND DAY SHIFT MAY NEED TO CONSIDER A HIGH WIND WARNING IN SOME AREAS IF THIS OCCURS. HAVE INCREASED HIGHS MOST AREAS TODAY INTO THE MIDDLE 60S. TONIGHT...SKIES WILL CLEAR ALL AREAS WITH DECREASING WINDS. DRIER AIR WILL PUSH SOUTH AND EAST...BUT NOT TOO FAR TO THE SOUTH OF THE CWA. STRONG SHORTWAVE...NOW MOVING INTO THE CA COAST WILL MOVE RAPIDLY EAST INTO THE SOUTHERN HIGH PLAINS LATE IN THE DAY AND SHOULD INDUCE CYCLOGENESIS WHICH WILL ALLOW FOR A RETURN FLOW OF THE MOISTURE THAT WAS POOLED TO THE SOUTH TO MOVE NORTHWARD IN THE DEVELOPING LLVL JET TUESDAY EVENING. THIS WILL RESULT IN INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS...MAINLY ACROSS THE SOUTHEAST HALF OF THE CWA TUESDAY NIGHT WITH RAIN...POSSIBLY MIXED WITH OR CHANGING TO SNOW AFTER MIDNIGHT NORTHWEST AREAS. AS THE SYSTEM DEEPENS OVER THE SOUTHERN PLAINS...THIS PRECIP COULD LINGER ACROSS THE CWA THE FIRST HALF OF THE DAY WEDNESDAY BEFORE MOVING RAPIDLY OFF TO THE EAST. WITH UPPER SYSTEM UNDERGOING RAPID STRENGTHENING...A CONCERN FOR A POSSIBLE RAPID CHANGEOVER TO SNOW...BUT IS STILL TOO FAR OUT TO FCST WITH HIGH CONFIDENCE AND WILL KEEP AS RAIN OR SNOW FOR NOW. NEXT SYSTEM STILL FCST TO ARRIVE WITH ANOTHER RAIN SNOW CHANCE BY THE END OF THE WEEK AS ACTIVE FLOW PATTERN CONTINUES. THIS IS WELL HANDLED WITH THE CURRENT FCST AND NO CHANGES MADE TO THE FCST BEYOND WEDNESDAY. && .AVIATION... FOR THE 06Z TAFS...BACKED OFF TIMING OF THE MVFR CIGS EVEN FURTHER AS LOW LEVEL EASTERLY FLOW HAS KEPT MVFR CIGS WELL OFF TO THE SOUTH AND EAST OF TAF SITES. INTRODUCED SOME LLWS INTO THE TAFS AS EASTERLY FLOW REMAINS DECOUPLED FROM THE INCREASING STRENGTH OF THE SOUTHERLY LOW LEVEL JET TONIGHT. KEPT IFR CIGS IN THE FORECAST AS LOW LEVEL SATURATION LOOKS LIKELY ONCE THE UPPER LEVEL SYSTEM PULLS INTO THE CENTRAL PLAINS THIS MORNING. LOW LEVEL WINDS LOOK TO REMAIN STRONG ON MONDAY...ESPECIALLY FOR LIGHT AIRCRAFT. CAVANAUGH && .TOP WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FROM 9AM UNTIL 6PM TODAY FOR ENTIRE FORECAST AREA. && $$
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
505 AM CST MON FEB 9 2009 .UPDATE... UPDATED TO INCLUDE 12Z AVIATION DISCUSSION. && .DISCUSSION... VERY COMPLEX WEATHER SCENARIO DEVELOPING ACROSS THE UPPER MIDWEST AS DEEP MOISTURE SURGES NORTHWARD WITH SURFACE TEMPERATURES NEAR THE FREEZING MARK. RECENT RADAR RETURNS AS OF 130 AM...HAD MOST OF THE MEASURABLE PRECIPITATION IN THE FORM OF RAIN ACROSS THE DAKOTAS AND NORTHWEST MINNESOTA WHERE BETTER DYNAMICS ASSOCIATED WITH 55KT LOW LEVEL JET HAD OCCURRED. ALTHOUGH MOST AREAS HAVE SURFACE TEMPERATURES IN THE LOW TO MID 30S...FAR NORTHWEST MINNESOTA DID INDICATE SUBSTANTIAL SUB FREEZING TEMPERATURES. IN ADDITION...RUC13 AND EVEN SOME OF ACARS DATA EARLIER TONIGHT HAS A PRONOUNCED ELEVATED WARM LAYER WITH 85H TEMPS NEAR 10C. RUC13 ALSO IS ADVERTISING WET BULB TEMPERATURES ABOVE 0C EXCEPT IN WESTERN WISCONSIN AND EAST CENTRAL MINNESOTA WHERE PRECIPITATION HASN`T STARTED YET. MAIN FORECAST CONCERN THIS MORNING WILL BE THE FREEZING RAIN ADVISORY AND IF THIS CAN BE CANCELED OR AT LEAST TRIMMED BACK TO ONLY THE FAR NORTHERN CWA. WILL MAKE LAST MINUTE CALL OF THIS SCENARIO BUT ALL INDICATIONS IS TO CANCEL THE ADVISORY BEFORE 6 AM. ALTHOUGH PRECIPITATION IS A GOOD BIT TODAY AS WARM AIR ADVECTION/MOISTURE WILL SATURATE THE ATMOSPHERE BY LATER THIS MORNING...THERE ARE SOME CONCERNS WITH THE ALREADY DRY AIRMASS ACROSS THE EASTERN CWA ALLOWING FOR MOSTLY SCATTERED OR ISOLATED PRECIPITATION THIS MORNING. HIGHLY EFFICIENT PRECIPITATION PRODUCING CLOUDS WILL LIKELY HOLD OFF UNTIL LATER THIS AFTERNOON AS THE MAIN UPPER LOW MOVES ACROSS THE AREA. IN ADDITION...ELEVATED INSTABILITY OF 250/400 J/KG ASSOCIATED WITH THIS FEATURE...WILL ENHANCE THE CONVECTIVE POTENTIAL AND ALLOW FOR ISOLATED THUNDERSTORMS TO DEVELOP. QPF AMOUNTS WILL LIKELY BE LOW DUE TO THIS TIME OF YEAR...BUT INCREDIBLE PRECIPITABLE WATER VALUES OF 200/300% ABOVE NORMAL AND THE CHANCE OF CONVECTION WILL LEAD TO ISOLATED HEAVY RAINFALL AND THE POSSIBILITY OF LOCALIZED FLOODING WHERE AREAS OF POOR DRAINAGE AND SNOW COVER EXISTS. ONCE THIS MAIN WAVE MOVES ACROSS THE AREA...MOST OF THE STEADIER PRECIPITATION WILL BE CONCENTRATED NEAR THE UPPER LOW WHERE IT IS PROGGED TO SLOWLY MOVE ACROSS WESTERN MINNESOTA AND INTO NORTHERN MINNESOTA BY TUESDAY AFTERNOON. THUS...PRECIPITATION CHANCES WILL INCREASE FURTHER NORTHWEST ACROSS OUR CWA. IN ADDITION...THERMODYNAMIC PROFILES INDICATE THAT COLDER AIR WRAPPING AROUND THIS UPPER LOW...WILL FINALLY ALLOW FOR SNOW TO MIX IN...ESPECIALLY ACROSS WESTERN MINNESOTA AFTER MIDNIGHT. THE PRECIPITATION SHOULD SLOWLY END ACROSS CENTRAL MINNESOTA ON TUESDAY WITH SOME LIGHT SNOW POSSIBLE ON WEDNESDAY AS ANOTHER UNORGANIZED DISTURBANCE MOVES ACROSS THE REGION. QPF AMOUNTS WILL REMAIN LOW ENOUGH FOR TRACE SNOWFALL AMOUNTS OR UNDER AN INCH. NO CHANGES IN THE EXTENDED OUTLOOK AS MODELS CONTINUE THE TREND OF MOST OF THE ACTIVE WEATHER REMAINING SOUTH OF THE FORECAST AREA. && .AVIATION.../12Z TAF ISSUANCE/ A BUSY AND PREDOMINANTLY IFR AVIATION FORECAST PERIOD OVER THE NEXT 24 HOURS AS LOW PRESSURE LIFTS NORTHEAST TOWARD THE AREA. WATER VAPOR IMAGERY SHOWS THE HEALTHY AND NEGATIVELY TILTED SHORTWAVE LIFTING NORTHEAST FROM THE SOUTHERN ROCKIES TOWARD THE CENTRAL PLAINS. THIS FEATURE WILL CONTINUE TO LIFT NORTHEAST THROUGH THE DAY... WITH A GOOD SOUTHERLY FEED OF WARMER AIR AND MOISTURE OUT AHEAD OF IT UP INTO OUR AREA. DIFFUSE WARM ADVECTION WILL REMAIN OVER THE AREA THROUGH THE DAY... WHICH SHOULD CONTINUE TO KEEP SOME SPOTTY AREAS OF PCPN GOING INTO EARLY AFTERNOON. DURING THE AFTERNOON HOURS BETTER FORCING ASSOCIATED WITH THE UPPER WAVE WILL OVERSPREAD THE AREA FROM SOUTH TO NORTH... WHICH SHOULD HELP FOCUS A PERIOD OF STEADIER PCPN. UNTIL THEN... CEILINGS AND VISIBILITIES WILL BE SOMEWHAT OF A CHALLENGE GIVEN THE PERSISTENT MOIST FLOW AND WEAK FORCING. CURRENT OBS SHOW A GOOD SURGE OF LOWER CEILINGS AND VISIBILITIES MOVING INTO THE SOUTHWEST HALF OF THE AREA... AND EXPECT THESE 500-1000FT AGL CEILINGS AND VISIBILITIES BELOW 3NM TO WORK THEIR WAY NORTH AND EAST OVER A GOOD PART OF THE FORECAST AREA THROUGH THE MORNING. HOWEVER... FARTHER SOUTH OVER EASTERN NEBRASKA AND WESTERN IOWA SOME MVFR AND VFR CONDITIONS COULD BE FOUND IN THE LULL BETWEEN THE LEADING AREA OF WARM ADVECTION AND THE FORCING ASSOCIATED WITH THE SHORTWAVE ITSELF. THE MODELS SUGGEST THIS AREA FILLING IN WITH LOWER CLOUDS LATER THIS MORNING... WHICH SEEMS LIKE A SAFE BET NOW THAT THE SHORTWAVE IS EJECTING NORTHEAST TOWARD THE AREA. SO... WILL KEEP CEILINGS LOW THROUGH THE DAY... AND TRY TO TIME A WINDOW OF STEADIER PCPN DURING THE AFTERNOON INTO EARLY EVENING HOURS FROM SOUTH TO NORTH. LATEST OBS SHOW ALL TAF SITES EXCEPT KEAU AOA FREEZING... AND KEAU SHOULD MANAGE TO GET THERE BEFORE ANY PCPN DEVELOPS... SO DID NOT INCLUDE ANY MENTION OF FZRA IN THE FORECASTS. HOWEVER... WITH GROUND TEMPERATURES AOB FREEZING IN MOST SPOTS... THERE COULD BE SOME SLICK AREAS FOR A TIME THIS MORNING ON UNTREATED SURFACES. THE NAM AND PARTICULARLY THE GFS SUGGEST A DECENT DRY SLOT MOVING INTO AT LEAST THE SOUTH HALF OF THE AREA TONIGHT WHICH CERTAINLY MAKES SENSE GIVEN THE STRENGTH OF THE SYSTEM AND THE SLUG OF SUBSIDENCE/DRY AIR ALREADY APPARENT ON WATER VAPOR IMAGERY. SO... MADE SOME EFFORT TO BRING A PERIOD OF VFR CONDITIONS INTO THE SOUTH HALF OF THE AREA FOR A GOOD PART OF THE NIGHT UNTIL SOME STRATOCU PERHAPS COMES IN LATE TONIGHT. WIND SHEAR STILL LOOKS LIKE A REASONABLE POSSIBILITY THIS AFTERNOON AS THE SOUTHERLY LOW LEVEL JET REALLY PICKS UP AHEAD OF THE SYSTEM... SO KEPT A MENTION OF THAT IN THE FORECAST EVEN WITH SOME SURFACE GUSTS ALSO POSSIBLE GIVEN THE 50KT ADVERTISED AROUND 2K FT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR BENTON-CHISAGO- ISANTI-KANABEC-MILLE LACS-MORRISON-SHERBURNE. FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR DOUGLAS-POPE- STEARNS-STEVENS-TODD. WI...NONE. && $$ JLT/TRH