Forecast Discussions mentioning any of "HRRR" "RR" "RUC13" "RUC" received at GSD on 12/04/11


AREA FORECAST DISCUSSION...CORRECTION
NWS GRAND JUNCTION CO
308 PM MST FRI DEC 2 2011 CORRECTED SHORT TERM TIME PERIOD DESCRIPTOR .SHORT TERM /TONIGHT THROUGH SUNDAY/... THE CLOSED LOW OVER AZ FINALLY BEGINNING TO OPEN UP AND IS EXPECTED TO EJECT THROUGH NM AND THE 4 CORNERS TONIGHT AS THE NEXT TROUGH DIVES DOWN TO REPLACE IT. MOISTURE HAS SPREAD ACROSS MUCH SE UT AND WRN CO TODAY AND NICELY CAPTURED ON THE 300K POTENTIAL TEMP SURFACE...WITH LIGHT SNOW REPORTED OVER HIGHER TERRAIN FROM MOUNT WERNER ABOVE STEAMBOAT SPGS TO GRAND MESA TO THE SAN JUAN MTNS. SNOW ALSO ALONG THE SRN BASE OF THE SAN JUANS FROM CORTEZ TO PAGOSA IN THE UPSLOPE FLOW. RUC MODELS SHOWS A COUPLE WAVES OF ENERGY MOVING UP FROM THE LOW...SO EXPECT SNOW INTENSITY TO VARY THROUGH THE NIGHT IN SW CO. CURRENT WINTER HIGHLIGHTS FOR THE SAN JUAN/ABAJO/LA SAL MTNS AND THE DURANGO-PAGOSA AREA LOOK ON TRACK. THE SECOND SPLITTING TROUGH WAS DROPPING ACROSS ID AND DRIVEN BY A 120 KT UPPER JET OVER THE PAC NW. THIS TROUGH EXPECTED TO PUSH A COLD FRONT INTO NE UT/NW CO TONIGHT AND THEN INTO SE UT/SW CO SAT AS IT FORMS A SECOND CLOSED OVER AZ. RATHER NARROW BAND OF MOISTURE ASSOCIATED WITH THE TROUGH MOVING INTO NW UT...BUT EXPECT SNOW COVERAGE TO INCREASE OVER NE UT/NW CO TONIGHT AS THE FRONT INTERACTS WITH THE MOISTURE IN PLACE AHEAD OF THE AZ LOW. THE FRONT EXPECTED TO SLOW ACROSS THE N LATE TONIGHT...AND A PERIOD DECENT NORTHEAST OROGRAPHIC WINDS COMBINED WITH COLD ADVECTION SHOULD BRING 3-6 INCHES OF SNOW TO THE ERN UINTA MTNS...ESPECIALLY THEIR NORTH SLOPES. BUT...NORTHEAST WINDS NOT AS STRONG OR AS LONG IN DURATION AS THE STORM WED NIGHT...SO REFRAINED FROM ANY HIGHLIGHT FOR THE ERN UINTAS AT THIS TIME. A PERIOD OF GUSTY NE WINDS LIKELY ACROSS NW CO SAT MORNING AS WELL...BUT AGAIN NOT NEARLY AS STRONG AS WHAT OCCURRED THU MORNING. BOTH NAM AND GFS INDICATE A WEAK 700 MB LOW FORMS OVER WRN CO TONIGHT/SAT MORNING. BANKING ON ENHANCED LOW LEVEL CONVERGENCE AND EVENTUAL FRONTAL PASSAGE TO ENHANCE SNOWFALL FROM GRAND MESA TO THE WEST ELKS. WEST ELKS SHOULD ALSO BENEFIT FROM SOME MOIST SOUTHERLY OROGRAPHIC FLOW TONIGHT...WHILE TRAILING NORTHERLY FLOW MAY KEEP SOME LIGHT SNOW OVER GRAND MESA INTO SAT EVENING. AS SUCH... ELECTED TO INCLUDE THE GRAND MESA AND WEST ELKS /ZONES 9 AND 12/ IN A LOW-END ADVISORY TONIGHT INTO SAT EVENING FOR 4 TO 9 INCHES OF SNOW. THE 700 MB LOW SHOULD ALSO BRING SNOW TO MANY CENTRAL VALLEYS BUT WITH LITTLE ACCUMS EXPECTED. SNOW DIMINISHES SAT NIGHT WITH CLEARING FROM THE NW. ERN UT/WRN CO SHOULD BE IN BETWEEN SYSTEMS SUNDAY AS MODELS SHOW YET A THIRD SPLITTING TROUGH APPROACHING FROM THE N LATE IN THE WEEKEND. WILL TREND THE CHANCE OF PRECIP UP AGAIN ACROSS THE NORTHERN MTNS SUNDAY AFTERNOON AS A RESULT. .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... THE EARLY PART OF THE LONG TERM IS A CONTINUATION OF A REPEATING PATTERN THAT HAS BEEN IN CONTROL SINCE THIS MIDWEEK. THE LAST OF A SERIES OF SHORTWAVES WILL DROP SOUTHWARD INTO ARIZONA AND AGAIN FORM A LOW TO OUR SOUTHWEST SUNDAY NIGHT INTO MONDAY. TODAY`S RUNS ARE FARTHER WEST THAN YESTERDAY`S...WHICH DOES NOT ALLOW THE BEST MOISTURE/DYNAMICS/OROGRAPHICS TO MOVE OVER OUR FORECAST AREA. THAT SAID...THIS DISTURBANCE WILL BE IN CLOSE ENOUGH PROXIMITY FOR ANOTHER ROUND OF MOUNTAIN SNOWFALL...WITH A CHANCE OF SNOW IN MANY VALLEYS. THE FAVORED AREA WILL SWITCH FROM THE NORTH TO THE SOUTH LATE SUNDAY NIGHT...WITH CLEARING OVER THE NORTH DURING THE DAY ON MONDAY. WINDS DO NOT SEEM TO BE AS STRONG AS YESTERDAY`S SYSTEM...SO DO NOT ANTICIPATE NEARLY AS MUCH BLOWING SNOW. WE CONTINUE TO SEE SOME DISCREPANCIES IN RUN-TO-RUN AND BETWEEN-MODEL SOLUTIONS FOR THE UPCOMING LONG TERM PERIOD. TODAY`S RUNS KEEP THE AREA DRY THROUGH THE REMAINDER OF THE PERIOD. WE SIT UNDER A DRY AND COLD NORTHWEST FLOW AS HIGH PRESSURE DOMINATES THE WEST COAST THROUGH THE GREAT BASIN. THIS PATTERN IS NOW PROGGED TO PERSIST THROUGH THE WORK WEEK. MODELS INDICATE THAT THERE MAY BE A COUPLE WEAK WAVES THAT BRUSH THE NORTHERN EDGE...BUT THE TIMING AND TRACK IS BOUND TO CHANGE WITH FUTURE MODEL RUNS. TEMPERATURES WILL BE BELOW NORMAL IN THE DRY AIR MASS...ESPECIALLY AT NIGHT. SOME MODIFICATION IS EXPECTED TOWARDS THE END OF THE PERIOD. ANY WAVES THAT BRUSH THE AREA WILL ACT TO MODIFY TEMPS...AGAIN MAINLY AT NIGHT. && .AVIATION /FOR 00Z TAF ISSUANCE/... SNOW HAS DEVELOPED OVER MANY MOUNTAIN AREAS AND IN SOME SOUTHERN VALLEYS THIS AFTERNOON. THIS ACTIVITY IS EXPECTED TO BECOME MORE WIDESPREAD THIS EVENING AND OVERNIGHT. THEREFORE MVFR/IFR VIS/CIGS IS EXPECTED MUCH OF THE TIME OVER THE MOUNTAINS...AND FOR SHORTER PERIODS IN THE VALLEYS. BY MIDNIGHT ALL TAF SITES WILL HAVE A CHANCE OF MVFR/IFR AS THE CHANCE FOR PRECIPITATION SPREADS INTO THE LOWER VALLEYS. SNOW AND LOW CLOUDS WILL CONTINUE...DIMINISHING FROM THE NORTH DURING THE AFTERNOON. THEREFORE PERIODS OF MVFR/IFR ARE EXPECTED THROUGH THE DAY. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL 11 PM MST SATURDAY FOR ZONES 9/12/18. WINTER STORM WARNING UNTIL 11 PM MST SATURDAY FOR ZONE 019. WINTER WEATHER ADVISORY UNTIL 2 PM MST SATURDAY FOR ZONES 22/23. UT...WINTER WEATHER ADVISORY UNTIL 11 PM MST SATURDAY FOR ZONE 28. && $$ SHORT TERM...JAD LONG TERM....EH AVIATION.....EH
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
305 PM MST FRI DEC 2 2011 .SHORT TERM /TODAY THROUGH SATURDAY NIGHT/... THE CLOSED LOW OVER AZ FINALLY BEGINNING TO OPEN UP AND IS EXPECTED TO EJECT THROUGH NM AND THE 4 CORNERS TONIGHT AS THE NEXT TROUGH DIVES DOWN TO REPLACE IT. MOISTURE HAS SPREAD ACROSS MUCH SE UT AND WRN CO TODAY AND NICELY CAPTURED ON THE 300K POTENTIAL TEMP SURFACE...WITH LIGHT SNOW REPORTED OVER HIGHER TERRAIN FROM MOUNT WERNER ABOVE STEAMBOAT SPGS TO GRAND MESA TO THE SAN JUAN MTNS. SNOW ALSO ALONG THE SRN BASE OF THE SAN JUANS FROM CORTEZ TO PAGOSA IN THE UPSLOPE FLOW. RUC MODELS SHOWS A COUPLE WAVES OF ENERGY MOVING UP FROM THE LOW...SO EXPECT SNOW INTENSITY TO VARY THROUGH THE NIGHT IN SW CO. CURRENT WINTER HIGHLIGHTS FOR THE SAN JUAN/ABAJO/LA SAL MTNS AND THE DURANGO-PAGOSA AREA LOOK ON TRACK. THE SECOND SPLITTING TROUGH WAS DROPPING ACROSS ID AND DRIVEN BY A 120 KT UPPER JET OVER THE PAC NW. THIS TROUGH EXPECTED TO PUSH A COLD FRONT INTO NE UT/NW CO TONIGHT AND THEN INTO SE UT/SW CO SAT AS IT FORMS A SECOND CLOSED OVER AZ. RATHER NARROW BAND OF MOISTURE ASSOCIATED WITH THE TROUGH MOVING INTO NW UT...BUT EXPECT SNOW COVERAGE TO INCREASE OVER NE UT/NW CO TONIGHT AS THE FRONT INTERACTS WITH THE MOISTURE IN PLACE AHEAD OF THE AZ LOW. THE FRONT EXPECTED TO SLOW ACROSS THE N LATE TONIGHT...AND A PERIOD DECENT NORTHEAST OROGRAPHIC WINDS COMBINED WITH COLD ADVECTION SHOULD BRING 3-6 INCHES OF SNOW TO THE ERN UINTA MTNS...ESPECIALLY THEIR NORTH SLOPES. BUT...NORTHEAST WINDS NOT AS STRONG OR AS LONG IN DURATION AS THE STORM WED NIGHT...SO REFRAINED FROM ANY HIGHLIGHT FOR THE ERN UINTAS AT THIS TIME. A PERIOD OF GUSTY NE WINDS LIKELY ACROSS NW CO SAT MORNING AS WELL...BUT AGAIN NOT NEARLY AS STRONG AS WHAT OCCURRED THU MORNING. BOTH NAM AND GFS INDICATE A WEAK 700 MB LOW FORMS OVER WRN CO TONIGHT/SAT MORNING. BANKING ON ENHANCED LOW LEVEL CONVERGENCE AND EVENTUAL FRONTAL PASSAGE TO ENHANCE SNOWFALL FROM GRAND MESA TO THE WEST ELKS. WEST ELKS SHOULD ALSO BENEFIT FROM SOME MOIST SOUTHERLY OROGRAPHIC FLOW TONIGHT...WHILE TRAILING NORTHERLY FLOW MAY KEEP SOME LIGHT SNOW OVER GRAND MESA INTO SAT EVENING. AS SUCH... ELECTED TO INCLUDE THE GRAND MESA AND WEST ELKS /ZONES 9 AND 12/ IN A LOW-END ADVISORY TONIGHT INTO SAT EVENING FOR 4 TO 9 INCHES OF SNOW. THE 700 MB LOW SHOULD ALSO BRING SNOW TO MANY CENTRAL VALLEYS BUT WITH LITTLE ACCUMS EXPECTED. SNOW DIMINISHES SAT NIGHT WITH CLEARING FROM THE NW. ERN UT/WRN CO SHOULD BE IN BETWEEN SYSTEMS SUNDAY AS MODELS SHOW YET A THIRD SPLITTING TROUGH APPROACHING FROM THE N LATE IN THE WEEKEND. WILL TREND THE CHANCE OF PRECIP UP AGAIN ACROSS THE NORTHERN MTNS SUNDAY AFTERNOON AS A RESULT. .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... THE EARLY PART OF THE LONG TERM IS A CONTINUATION OF A REPEATING PATTERN THAT HAS BEEN IN CONTROL SINCE THIS MIDWEEK. THE LAST OF A SERIES OF SHORTWAVES WILL DROP SOUTHWARD INTO ARIZONA AND AGAIN FORM A LOW TO OUR SOUTHWEST SUNDAY NIGHT INTO MONDAY. TODAY`S RUNS ARE FARTHER WEST THAN YESTERDAY`S...WHICH DOES NOT ALLOW THE BEST MOISTURE/DYNAMICS/OROGRAPHICS TO MOVE OVER OUR FORECAST AREA. THAT SAID...THIS DISTURBANCE WILL BE IN CLOSE ENOUGH PROXIMITY FOR ANOTHER ROUND OF MOUNTAIN SNOWFALL...WITH A CHANCE OF SNOW IN MANY VALLEYS. THE FAVORED AREA WILL SWITCH FROM THE NORTH TO THE SOUTH LATE SUNDAY NIGHT...WITH CLEARING OVER THE NORTH DURING THE DAY ON MONDAY. WINDS DO NOT SEEM TO BE AS STRONG AS YESTERDAY`S SYSTEM...SO DO NOT ANTICIPATE NEARLY AS MUCH BLOWING SNOW. WE CONTINUE TO SEE SOME DISCREPANCIES IN RUN-TO-RUN AND BETWEEN-MODEL SOLUTIONS FOR THE UPCOMING LONG TERM PERIOD. TODAY`S RUNS KEEP THE AREA DRY THROUGH THE REMAINDER OF THE PERIOD. WE SIT UNDER A DRY AND COLD NORTHWEST FLOW AS HIGH PRESSURE DOMINATES THE WEST COAST THROUGH THE GREAT BASIN. THIS PATTERN IS NOW PROGGED TO PERSIST THROUGH THE WORK WEEK. MODELS INDICATE THAT THERE MAY BE A COUPLE WEAK WAVES THAT BRUSH THE NORTHERN EDGE...BUT THE TIMING AND TRACK IS BOUND TO CHANGE WITH FUTURE MODEL RUNS. TEMPERATURES WILL BE BELOW NORMAL IN THE DRY AIR MASS...ESPECIALLY AT NIGHT. SOME MODIFICATION IS EXPECTED TOWARDS THE END OF THE PERIOD. ANY WAVES THAT BRUSH THE AREA WILL ACT TO MODIFY TEMPS...AGAIN MAINLY AT NIGHT. && .AVIATION /FOR 00Z TAF ISSUANCE/... SNOW HAS DEVELOPED OVER MANY MOUNTAIN AREAS AND IN SOME SOUTHERN VALLEYS THIS AFTERNOON. THIS ACTIVITY IS EXPECTED TO BECOME MORE WIDESPREAD THIS EVENING AND OVERNIGHT. THEREFORE MVFR/IFR VIS/CIGS IS EXPECTED MUCH OF THE TIME OVER THE MOUNTAINS...AND FOR SHORTER PERIODS IN THE VALLEYS. BY MIDNIGHT ALL TAF SITES WILL HAVE A CHANCE OF MVFR/IFR AS THE CHANCE FOR PRECIPITATION SPREADS INTO THE LOWER VALLEYS. SNOW AND LOW CLOUDS WILL CONTINUE...DIMINISHING FROM THE NORTH DURING THE AFTERNOON. THEREFORE PERIODS OF MVFR/IFR ARE EXPECTED THROUGH THE DAY. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL 11 PM MST SATURDAY FOR ZONES 9/12/18. WINTER STORM WARNING UNTIL 11 PM MST SATURDAY FOR ZONE 019. WINTER WEATHER ADVISORY UNTIL 2 PM MST SATURDAY FOR ZONES 22/23. UT...WINTER WEATHER ADVISORY UNTIL 11 PM MST SATURDAY FOR ZONE 28. && $$ SHORT TERM...JAD LONG TERM....EH AVIATION.....EH
AREA FORECAST DISCUSSION
NWS NEW YORK NY
647 PM EST SAT DEC 3 2011 .SYNOPSIS... HIGH PRESSURE OVER THE AREA MOVES OFFSHORE TONIGHT...AND CONTINUES TO TRACK EAST INTO THE START OF THE NEW WEEK. A SERIES OF LOW PRESSURE CENTERS WILL RIDE ALONG A COLD FRONT THAT SLOWLY MOVES THROUGH BY MID TO LATE WEEK. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... HIGH PRESSURE SLOWLY PASSING EAST...WITH LIGHT ONSHORE FLOW EXPECTED OVERNIGHT. SATELLITE INDICATES PLENTY OF CIRRUS MOVING OVERHEAD AS UPPER RIDGE AXIS SHIFTS EAST. IN ADDITION...SOME STRATUS TO THE EAST COULD APPROACH AND AFFECT PORTIONS OF THE AREA...ESPECIALLY EASTERN LOCALES. EVEN IF THE STRATUS DOES NOT ADVECT IN FROM THE EAST...TIME HEIGHTS FROM RUC INDICATING POSSIBLE STRATUS DEVELOPMENT LATER TONIGHT. SINCE THIS IS THE FIRST NIGHT OF ONSHORE FLOW...NOT EXPECTING WIDESPREAD STRATUS AND FOG...BUT THIS WILL NEED TO BE WATCHED. AS FOR TEMPS...COULD VERY WELL SEE TEMPERATURES REMAIN NEARLY STEADY OR RISE FROM THE CHILLY EVENING READINGS. THIS DUE TO INCREASING MARINE LAYER AS LOW LEVEL WINDS SHIFT E/SE...ALBEIT LIGHT. ALSO...CIRRUS MAY PREVENT TEMPS FROM BOTTOMING OUT. AGAIN...THIS WILL NEED TO BE MONITORED TONIGHT. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/... SOUTHERLY FLOW...ALONG WITH A RISE IN H8 TEMPS...WILL ALLOW FOR A MOSTLY SUNNY DAY WITH TEMPS A FEW DEGREES WARMER THAN SATURDAY. CLOUDS WILL INCREASE LATE IN THE DAY AS A STORM SYSTEM OVER THE MIDWEST MOVES INTO THE GREAT LAKES ON SUNDAY...THEN NORTHEAST INTO EASTERN CANADA AND THE CANADIAN MARITIMES SUNDAY NIGHT THROUGH MONDAY MORNING. THE INCREASE IN CLOUDS WILL ALLOW TEMPS TO HOLD STEADY AND THEN BEGIN TO DROP IN THE AFTERNOON SUNDAY. HIGHS WILL TOP OFF IN THE LOW TO MID 50S ACROSS NORTHERN ZONES AND IN THE MID TO UPPER 50S ACROSS SOUTHERN ZONES. SEVERAL SHORTWAVES WILL MOVE THROUGH THE REGION SUNDAY NIGHT THROUGH MONDAY AS A SECONDARY LOW FORMS OVER THE GULF COAST STATES ON MONDAY. FOR THE LOCAL AREA...CAN EXPECT A PARTLY TO MOSTLY CLOUDY DAY...BUT WITH H8 TEMPS WARMING TO 4-6C...ALONG WITH A SOUTHERLY FLOW...TEMPS WILL REMAIN MILD ON MONDAY...TOPPING OFF IN THE MID TO UPPER 50S. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... UNSETTLED AND SOMEWHAT UNCERTAIN PATTERN...AT LEAST WITH REGARD TO SUBTLE DETAILS. LOOKING AT THE BIG PICTURE ACROSS THE NORTHERN HEMISPHERE...COLD CORE LOW NEAR ALASKA SLOWLY SETTLES ACROSS CENTRAL CANADA IN TIME. FURTHER SOUTH...TROUGH OUT WEST WILL EVENTUALLY EJECT EAST. THIS TROUGH ELONGATED FROM NORTHEAST TO SOUTHWEST...WITH A GENERAL AND BROAD SOUTHWEST FLOW FOR OUR AREA. THIS PATTERN WILL RESULT IN A SLOW PROGRESSION TO THE SFC COLD FRONT. EMBEDDED SHORTWAVES IN THIS SOUTHWEST FLOW WILL SET THE STAGE FOR AT LEAST TWO AREAS OF LOW PRESSURE THAT WILL RIDE ALONG THE FRONT. UNSETTLED WEATHER WILL BE THE RESULT...WITH PERHAPS THE HIGHEST POPS BY MID WEEK AS TROUGH OUT WEST BEGINS IT/S EASTWARD APPROACH. FOR NOW...FOLLOWED HPC GUIDANCE AS GFS APPEARS TO BE AN AMPLIFIED OUTLIER BY MID TO LATE WEEK. MILD...ABOVE NORMAL TEMPS EXPECTED UNTIL THE FRONT FINALLY MOVES THROUGH...SOMETIME WEDNESDAY OR WEDNESDAY NIGHT. THEN READINGS SHOULD FALL BACK CLOSER TO NORMAL FOR THE LATTER PORTION OF THE WEEK. IF GFS IS INDEED CORRECT...ONE MORE MILD DAY COULD BE REALIZED THURSDAY...BUT AGAIN WILL LEAN AWAY FROM THIS SLOWER MORE AMPLIFIED SOLUTION AT THIS TIME. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... HIGH PRESSURE REMAINS OVER THE TERMINALS THROUGH THE TAF PERIOD. VFR THROUGH THIS EVENING. THERE IS A CHANCE OF LOW-END VFR /HIGH- END MVFR CEILINGS OVERNIGHT INTO SUNDAY MORNING. INTRODUCED SCT020 DECK IN MOST OF THE TAF SITES IN THE EARLY MORNING HOURS. LIGHT WINDS OVERNIGHT. HIGH CONFIDENCE OF S-SW WIND DIRECTION SUNDAY. OCCASIONAL GUSTS TO 15KT OR SLIGHTLY HIGHER SUNDAY AFTERNOON...BUT CONFIDENCE TOO LOW TO INCLUDE IN TAFS AT THIS TIME. OUTLOOK FOR 00Z SUNDAY THROUGH THURSDAY... SUN NIGHT...CHANCE OF MVFR VSBYS WITH FOG LATE SUN NIGHT INTO EARLY MON MORNING. MON...VFR. MON NIGHT-THURS...PERIODS OF SUB-VFR IN RAIN/SHOWERS. && .MARINE... HIGH PRES OVER THE WATERS MOVES OFFSHORE TONIGHT...AND REMAINS EAST OF THE WATERS BEFORE SLOWLY MOVING OVER THE OPEN ATLANTIC WATERS EARLY IN THE NEW WEEK. A PERSISTENT SOUTHERLY SWELL OVER THE OCEAN WATERS WILL RESULT IN SEAS UP TO 4 FT...AND MAY TOUCH 5 FT ON THE OUTER OCEAN WATERS FROM TIME TO TIME. DO NOT THINK SEAS WILL BE ABOVE 5 FT FOR A CONSISTENT PERIOD OF TIME...SO SCA NOT EXPECTED. SOUTHERLY WINDS WILL REMAIN AT 10 KT OR LESS. PERSISTENT SOUTHWEST OR SOUTH FLOW EXPECTED MONDAY THROUGH TUESDAY NIGHT AHEAD OF THE SLOW MOVING COLD FRONT. ONCE LOW PRESSURE AND THE FRONT MOVE EAST...WINDS PICK UP OUT OF THE NORTHWEST LATER WEDNESDAY AND THURSDAY. SEAS SHOULD REMAIN JUST BELOW OR PERHAPS RIGHT AT 5 FT THROUGH TUESDAY NIGHT/EARLY WEDNESDAY. BEHIND THE FRONT...SEAS BUILD AS WAVE WATCH III INDICATES. FOR THE OTHER WATERS SURROUNDING LONG ISLAND...WILL FOLLOW BUOY CLIMO BASED ON WINDS/FETCH. && .HYDROLOGY... DRY THROUGH MONDAY. UNSETTLED WEATHER WITH POSSIBLE SIGNIFICANT RAINFALL TUESDAY THROUGH WEDNESDAY. BEST CHANCE FOR ANY HEAVIER RAIN WOULD BE WEDNESDAY INTO WEDNESDAY NIGHT. STILL TOO EARLY TO DETERMINE EXTENT OF URBAN/RIVER FLOODING IF ANY. STAY TUNED. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...MPS/PW NEAR TERM...MPS/PW SHORT TERM...MPS LONG TERM...PW AVIATION...KCS MARINE...MPS/PW HYDROLOGY...MPS/PW
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1219 PM EST FRI DEC 2 2011 .SYNOPSIS... STRONG HIGH PRESSURE CENTERED IN THE PLAINS STATES HAS AN EXTENSION TO THE MID-ATLANTIC COAST BUT IS AWAITING THE PASSAGE OF A WEAK COLD FRONTAL PASSAGE THROUGH THE MID-ATLANTIC STATES LATER TODAY. THE HIGH THEN BUILDS STRONGLY INTO NEW ENGLAND SATURDAY AND EDGES OFFSHORE MONDAY. A COLD FRONT SHOULD BE STALLING OR DRIFTING EAST FROM THE APPALACHIAN MOUNTAINS MONDAY THROUGH AT LEAST WEDNESDAY AS A SERIES OF LOW PRESSURE SYSTEMS TRY TO MOVE NORTHEAST ALONG THE FRONT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... NOT TO MANY CHANGES WITH THIS UPDATE. A FRONTAL BOUNDARY WILL MOVE ACROSS NEW ENGLAND TODAY. BANDS OF HIGH CIRRUS CLOUDS ARE FORMING ACROSS THE PHILADELPHIA METRO REGION AND POINTS NORTH, THESE ARE ACCOUNTED FOR IN UPDATED SKY GRIDS. LATEST 16Z RUC KEEPS AND PRECIP WELL TO OUR NORTH. THIS FITS NICELY WITH RH VALUES NOT IDEAL FOR PRECIPITATION ALONG WITH WEEK LIFT CHARACTERIZED BY A LACK OF PVA AND 700 MB OMEGA. ANY RADAR ECHOS ACROSS THE NORTH THIS AFTERNOON WILL BE VIRGA. SURFACE TEMPERATURES HAVE REBOUNDED NICELY AHEAD OF THE FRONT EVEN AFTER A CHILLY START AND HAVE ADJUSTED TEMPERATURE GRIDS AGAIN BASED OFF OF 17Z METAR OBS. FRONT SHOULD BRING SOUTHERLY WINDS THIS AFTERNOON SWITCHING TO NORTHWESTERLY, MADE FEW CHANGES TO WIND. WIND GUSTS GRIDS BETTER MATCH SURROUNDING WFOS WITH THIS UPDATE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... TONIGHT IS A CLEAR NIGHT WITH A BIT OF NW BECOMING NORTH BREEZE DURING THE NIGHT AND TEMPS COOLING TO ABOUT THE SAME VALUES OR SLIGHTLY LOWER THAN WHAT OCCURRED THIS FROSTY FRIDAY MORNING. LOWERED THE TEMPS SLIGHTLY IN THE PHL-TTN URBAN CENTERS WITH NORTH WIND TONIGHT. && .LONG TERM /SATURDAY THROUGH THURSDAY/... FAIR WEATHER IS EXPECTED ACROSS THE AREA THIS WEEKEND AS HIGH PRESSURE REMAINS IN CONTROL OF THE WEATHER. BOTH THE EC AND GFS AGREE THAT THE HIGH WILL CREST OVER THE AREA SAT NIGHT AND THEN MOVE OFF INTO THE NORTH ATLANTIC SUN. SKIES WILL BE MOSTLY CLR SAT AND PARTLY TO MOSTLY CLR SUN. CLOUDS MAY ARRIVE LATER SUN WITH THE RETURN FLOW BEHIND THE HIGH BRINGING MOISTURE FROM OFF THE OCEAN. A LOW MOVES ACROSS SRN CANADA SUN NGT INTO MON CAUSING A FRONT TO DROP DOWN FROM THE NORTH. THIS FRONT STALLS ACROSS THE AREA ALLOWING ANOTHER LOW TO DEVELOP ON IT AND MOVE ACROSS THE AREA MON NGT INTO WED. THE GFS AND EC OFFER DIFFERENT SOLUTIONS WITH REGARDS TO HOW MUCH PRECIP ARRIVES AND WHEN. BOTH MODELS HAVE SOME QPF ARRIVING TUE...BUT THE EC HAS HEAVIER QPF ACROSS THE AREA WED NIGHT INTO THU WHILE THE GFS HAS THE BULK OF ITS QPF TUE NIGHT INTO WED. THE OVERNIGHT EXTENDED GRIDS HAVE MADE ONLY SMALL CHANGES TO THE EARLIER FCST WITH CHC POPS THROUGH MUCH OF THE MON NGT-THU PERIOD ATTM. A LITTLE SNOW MAY MIX IN WED NIGHT ACROSS THE NRN AREAS. && .AVIATION /17Z FRIDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...VFR MOSTLY CLEAR. PATCHY THICK CI ESPECIALLY 16Z-20Z...MAINLY N OF PHL. SCT CLDS 5000-8000 FT EXPECTED WITH THE LATE AFTN CFP. W GUSTS TO 15 KTS AT 18Z SHIFT NW AROUND 21Z WITH GUSTS 20 KTS... ISOLATED GUSTS TO 25 KTS POSSIBLE NEAR 23Z/2. TONIGHT...VFR CLEAR. NW WIND 5 TO 15 KTS BECOMING N DURING THE NIGHT. PHILADELPHIA SPECIFIC...HIGH CONFIDENCE FCST OF VFR CLEAR THROUGH 17Z WITH A BAND OF CI POSSIBLE 18Z-20Z. WIND AT 18Z W GUST 15 KT. AFTER 20Z...WSHIFT NW WITH GUSTS 20 KTS AND A FEW SC/CU 6000-8000 FT. LOW PROB ISO NW GUSTS 25 KTS IN THE 21Z-23Z TIME FRAME. OUTLOOK... VFR CONDITIONS EXPECTED SAT AND MUCH OF SUN. LOW CLOUDS MAY ARRIVE BEHIND THE DEPARTING HIGH LATER SUN INTO MON. POOR FLYING CONDITIONS TUE INTO THU WITH THE NEXT SYSTEM ARRIVING FROM THE MIDWEST STATES. && .MARINE... TODAY...LIGHT WIND TO START BECOMING INCREASINGLY GUSTY WEST THIS AFTN. TONIGHT...SCA ISSUED. MARGINAL CONFIDENCE IN THIS ADVY FOR SCT GUSTS 22-25 KTS MAINLY IN THE 23Z-05Z TIME FRAME. 44009 SEAS EXPECTED TO INCREASE TO 5 FT LATER TONIGHT SO HAVE TWO SEGMENTS... A NJ SEGMENT FOR THIS EVENING AND A LATER LENGTHIER TIME FRAME SEGMENT FOR THE DELAWARE ATLC WATERS. NO HEADLINE POSTED YET FOR LOWER DELAWARE BAY. THAT CAN BE ADDED LATER BY FUTURE SHIFTS IF CONFIDENCE INCREASES. STRUGGLED TO GET THE GRIDDED GUSTS TO CRITERIA VIA SEVERAL TOOL APPLICATIONS. SREF STILL NOT A HINT OF SUSTAINED 25 KT WINDS ALONG OUR COASTS. UPDATE: LOWERED WAVE HEIGHTS AGAIN SLIGHTLY FOR THE NEXT FEW HOURS BASED ON BUOY OBSERVATIONS WILL MONITOR THROUGHOUT THE DAY WITH RESPECT TO THE SMALL CRAFT ADV SET TO GO INTO EFFECT LATE THIS AFTERNOON. AGREE WITH PREVIOUS FORECASTER THINKING THAT IT IS QUESTIONABLE WE MEET SMALL CRAFT ADV CONDITIONS. OUTLOOK... HIGH PRESSURE WILL BE ACROSS THE WATERS THIS WEEKEND WITH WINDS AND SEAS EXPECTED TO REMAIN SUB-SCA THROUGH THE PERIOD. THE HIGH WILL MOVE AWAY EARLY NEXT WEEK WHILE LOW PRESSURE AND A SERIES OF FRONTS ARRIVE OVER OUR WATERS MON NGT INTO WED. WINDS AND SEAS WILL EVENTUALLY RISE INTO SCA CRITERIA PROBABLY BY TUE NIGHT AND THIS WILL PERSIST INTO THU. && .CLIMATE... DAILY CLI: GED 1203Z-1207Z TRACE OF SNOW IN CLEAR SKY REMOVED FROM THE 430PM CLI RUN. RAN THE MONTHLY CLM`S WITH JUST CURSORY CHECK OF THE DATA. IF YOU NOTICE ANY ERRORS PLEASE GIVE US A CALL. YOU SAW THE RER`S ISSUED EARLY THURSDAY MORNING REGARDING MONTHLY AND SEASONAL RANKING OF THE TEMPS/QPF! LA NINA OHIO VALLEY STORM TRACK CONTS TO LOOK ACTIVE AND MOST INDICATIONS ARE THAT THE PRECIPITATION EVENT FROM LATE MONDAY INTO WEDNESDAY WILL AT SOME POINT RAISE THE YEARLY WATER EQUIVALENT PCPN TOTAL AT KABE TO RECORD VALUES...NEEDING ONLY .16 INCHES TO EXCEED THE YEARLY RECORD OF 67.69 INCHES. NOTING THAT PHL AVG TEMP IS HEADED FOR ITS 13TH CONSECUTIVE ABOVE NORMAL DAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 1 AM EST SATURDAY FOR ANZ450>453. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EST SATURDAY FOR ANZ454-455. && $$ SYNOPSIS...DRAG/GORSE NEAR TERM...GAINES SHORT TERM...DRAG LONG TERM...O`HARA AVIATION...DRAG/O`HARA MARINE...DRAG/GAINES/O`HARA CLIMATE...
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
920 AM EST FRI DEC 2 2011 .SYNOPSIS... STRONG HIGH PRESSURE CENTERED IN THE PLAINS STATES HAS AN EXTENSION TO THE MID-ATLANTIC COAST BUT IS AWAITING THE PASSAGE OF A WEAK COLD FRONTAL PASSAGE THROUGH THE MID-ATLANTIC STATES LATER TODAY. THE HIGH THEN BUILDS STRONGLY INTO NEW ENGLAND SATURDAY AND EDGES OFFSHORE MONDAY. A COLD FRONT SHOULD BE STALLING OR DRIFTING EAST FROM THE APPALACHIAN MOUNTAINS MONDAY THROUGH AT LEAST WEDNESDAY AS A SERIES OF LOW PRESSURE SYSTEMS TRY TO MOVE NORTHEAST ALONG THE FRONT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... NOT TO MANY CHANGES WITH THIS UPDATE. A FRONTAL BOUNDARY WILL MOVE ACROSS NEW ENGLAND TODAY. THIS MAY RESULT IN SOME HIGH CIRRUS THIS AFTERNOON AS DISCUSSED BY PREVIOUS SHIFTS. LATEST 12Z RUC KEEPS ANY PRECIP WELL TO OUR NORTH. A CONCERN MAY BE SOME CAA THIS AFTERNOON BEHIND THE FRONT RESULTING IN THE LOWERING HIGH TEMPERATURES A TOUCH. CURRENT TEMPERATURES AND DEWPOINTS ALSO HAVE BEEN ADJUSTED SLIGHTLY BASED ON 14Z METAR OBS. FRONT SHOULD BRING SOUTHERLY WINDS THIS AFTERNOON SWITCHING TO NORTHWESTERLY, MADE FEW CHANGES TO WIND. LOWERED WAVE HEIGHTS SLIGHTLY FOR THE NEXT FEW HOURS BASED ON BUOY OBSERVATIONS WILL MONITOR THROUGHOUT THE DAY WITH RESPECT TO THE SMALL CRAFT ADVISORY SET TO GO INTO EFFECT LATE THIS AFTERNOON/TONIGHT. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... TONIGHT IS A CLEAR NIGHT WITH A BIT OF NW BECOMING NORTH BREEZE DURING THE NIGHT AND TEMPS COOLING TO ABOUT THE SAME VALUES OR SLIGHTLY LOWER THAN WHAT OCCURRED THIS FROSTY FRIDAY MORNING. LOWERED THE TEMPS SLIGHTLY IN THE PHL-TTN URBAN CENTERS WITH NORTH WIND TONIGHT. && .LONG TERM /SATURDAY THROUGH THURSDAY/... FAIR WEATHER IS EXPECTED ACROSS THE AREA THIS WEEKEND AS HIGH PRESSURE REMAINS IN CONTROL OF THE WEATHER. BOTH THE EC AND GFS AGREE THAT THE HIGH WILL CREST OVER THE AREA SAT NIGHT AND THEN MOVE OFF INTO THE NORTH ATLANTIC SUN. SKIES WILL BE MOSTLY CLR SAT AND PARTLY TO MOSTLY CLR SUN. CLOUDS MAY ARRIVE LATER SUN WITH THE RETURN FLOW BEHIND THE HIGHBRINGING MOISTURE FROM OFF THE OCEAN. A LOW MOVES ACROSS SRN CANADA SUN NGT INTO MON CAUSING A FRONT TO DROP DOWN FROM THE NORTH. THIS FRONT STALLS ACROSS THE AREA ALLOWING ANOTHER LOW TO DEVELOP ON IT AND MOVE ACROSS THE AREA MON NGT INTO WED. THE GFS AND EC OFFER DIFFERENT SOLUTIONS WITH REGARDS TO HOW MUCH PRECIP ARRIVES AND WHEN. BOTH MODELS HAVE SOME QPF ARRIVING TUE...BUT THE EC HAS HEAVIER QPF ACROSS THE AREA WED NIGHT INTO THU WHILE THE GFS HAS THE BULF OF ITS QPF TUE NIGHT INTO WED. THE OVERNIGHT EXTENDED GRIDS HAVE MADE ONLY SMALL CHANGES TO THE EARLIER FCST WITH CHC POPS THROUGH MUCH OF THE MON NGT-THU PERIOD ATTM. A LITTLE SNOW MAY MIX IN WED NIGHT ACROSS THE NRN AREAS. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...VFR MOSTLY CLEAR. PATCHY THICK CI ESPECIALLY 16Z-20Z...MAINLY N OF PHL. SCT CLDS 5000-8000 FT EXPECTED WITH THE LATE AFTN CFP. W GUSTS TO 15 KTS AT 18Z SHIFT NW AROUND 21Z WITH GUSTS 20 KTS... ISOLATED GUSTS TO 25 KTS POSSIBLE NEAR 23Z/2. TONIGHT...VFR CLEAR. NW WIND 5 TO 15 KTS BECOMING N DURING THE NIGHT. PHILADELPHIA SPECIFIC...HIGH CONFIDENCE FCST OF VFR CLEAR THROUGH 17Z WITH A BAND OF CI POSSIBLE 18Z-20Z. WIND AT 18Z W GUST 15 KT. AFTER 20Z...WSHIFT NW WITH GUSTS 20 KTS AND A FEW SC/CU 6000-8000 FT. LOW PROB ISO NW GUSTS 25 KTS IN THE 21Z-23Z TIME FRAME. OUTLOOK... VFR CONDITIONS EXPECTED SAT AND MUCH OF SUN. LOW CLOUDS MAY ARRIVE BEHIND THE DEPARTING HIGH LATER SUN INTO MON. POOR FLYING CONDITIONS TUE INTO THU WITH THE NEXT SYSTEM ARRIVING FROM THE MIDWEST STATES. && .MARINE... TODAY...LIGHT WIND TO START BECOMING INCREASINGLY GUSTY WEST THIS AFTN. TONIGHT...SCA ISSUED. MARGINAL CONFIDENCE IN THIS ADVY FOR SCT GUSTS 22-25 KTS MAINLY IN THE 23Z-05Z TIME FRAME. 44009 SEAS EXPECTED TO INCREASE TO 5 FT LATER TONIGHT SO HAVE TWO SEGMENTS... A NJ SEGMENT FOR THIS EVENING AND A LATER LENGTHIER TIME FRAME SEGMENT FOR THE DELAWARE ATLC WATERS. NO HEADLINE POSTED YET FOR LOWER DELAWARE BAY. THAT CAN BE ADDED LATER BY FUTURE SHIFTS IF CONFIDENCE INCREASES. STRUGGLED TO GET THE GRIDDED GUSTS TO CRITERIA VIA SEVERAL TOOL APPLICATIONS. SREF STILL NOT A HINT OF SUSTAINED 25 KT WINDS ALONG OUR COASTS. OUTLOOK... HIGH PRESSURE WILL BE ACROSS THE WATERS THIS WEEKEND WITH WINDS AND SEAS EXECTED TO REMAIN SUB-SCA THROUGH THE PERIOD. THE HIGH WILL MOVE AWAY EARLY NEXT WEEK WHILE LOW PRESSURE AND A SERIES OF FRONTS ARRIVE OVER OUR WATERS MON NGT INTO WED. WINDS AND SEAS WILL EVENTUALLY RISE INTO SCA CRITERIA PROBABLY BY TUE NIGHT AND THIS WILL PERSIST INTO THU. && .CLIMATE... DAILY CLI: GED 1203Z-1207Z TRACE OF SNOW IN CLEAR SKY REMOVED FROM THE 430PM CLI RUN. RAN THE MONTHLY CLM`S WITH JUST CURSORY CHECK OF THE DATA. IF YOU NOTICE ANY ERRORS PLEASE GIVE US A CALL. YOU SAW THE RER`S ISSUED EARLY THURSDAY MORNING REGARDING MONTHLY AND SEASONAL RANKING OF THE TEMPS/QPF! LA NINA OHIO VALLEY STORM TRACK CONTS TO LOOK ACTIVE AND MOST INDICATIONS ARE THAT THE PRECIPITATION EVENT FROM LATE MONDAY INTO WEDNESDAY WILL AT SOME POINT RAISE THE YEARLY WATER EQUIVALENT PCPN TOTAL AT KABE TO RECORD VALUES...NEEDING ONLY .16 INCHES TO EXCEED THE YEARLY RECORD OF 67.69 INCHES. NOTING THAT PHL AVG TEMP IS HEADED FOR ITS 13TH CONSECUTIVE ABOVE NORMAL DAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 1 AM EST SATURDAY FOR ANZ450>453. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EST SATURDAY FOR ANZ454-455. && $$ SYNOPSIS...DRAG/GORSE NEAR TERM...GAINES SHORT TERM...DRAG LONG TERM...O`HARA AVIATION...DRAG/O`HARA MARINE...DRAG/O`HARA CLIMATE...
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
954 AM EST FRI DEC 2 2011 .UPDATE... THE NEAR TERM SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... A WEAKENING COLD FRONT FROM NORTHERN INDIANA TO SOUTHEAST MISSOURI WILL MOVE INTO OUR REGION LATER TODAY AND GRADUALLY DISSIPATE. AN AREA OF HIGH PRESSURE BEHIND THE FRONT WILL DOMINATE OUR WEATHER TONIGHT AND SATURDAY. RAIN WILL SPREAD INTO OUR REGION LATE SATURDAY NIGHT AND SUNDAY AS ANOTHER AND STRONGER COLD FRONT MOVES OUR WAY. SEVERAL MODELS STALL THIS FRONT FROM THE LOWER MISSISSIPPI VALLEY TO OHIO EARLY NEXT WEEK...KEEPING SOUTHERN SECTIONS VERY WET. FARTHER NORTH MIXED PRECIP WILL BE THE RULE AS COLDER AIR SPREADS INTO OUR REGION. FINALLY DRY AND COLD WEATHER WILL BE THE RULE AFTER THE MIDDLE OF NEXT WEEK AS THE FRONT TO OUR EAST MOVES EAST AND HIGH PRESSURE OVER THE ROCKIES BUILDS OUR WAY. && .NEAR TERM /REST OF TODAY/... UPDATE...FORECAST GENERALLY LOOKS TO BE IN GREAT SHAPE. ONLY NEEDED TO MAKE A FEW MINOR TWEAKS TO ACCOUNT FOR LATEST TRENDS. BY MIDDAY MODELS SHOW QUITE A BIT OF DRYING AS HIGH PRESSURE BUILDS INTO THE GREAT LAKES AND DOWNWARD VERTICAL VELOCITIES OCCUR...SKIES SHOULD BECOME MOSTLY SUNNY EVERYWHERE LATE. VISIBLE SATELLITE AND OBSERVATIONS INDICATE A LITTLE REMAINING SNOW COVER ACROSS PARTS OF OUR FAR NORTH AND NORTHEAST WHICH MAY HOLD TEMPERATURES DOWN THERE JUST A LITTLE. OTHERWISE...WENT NEAR A MAV/MET BLEND ON TEMPERATURES MOST OTHER AREAS TODAY FOR HIGHS IN THE 40S. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... MODELS ARE IN GOOD AGREEMENT THIS PERIOD SO USED A BLEND WITH ONLY MINOR ADJUSTMENTS. SATURDAY WILL BE MILD AND DRY AS A SOUTHERLY FLOW INCREASES ACROSS OUR REGION AS THE RESULT OF HIGH PRESSURE OVER THE EASTERN U.S. AND LOW PRESSURE MOVING FROM THE CENTRAL PLAINS TOWARDS THE GREAT LAKES. MODELS THIS RUN ARE A TAD SLOWER IN BEGINNING PRECIP MAINLY LATE SATURDAY NIGHT AND MAINTAINING IT A LITTLE FARTHER NORTH SUNDAY AND SUNDAY NIGHT. A COLD FRONT WILL MOVE EAST ACROSS OUR REGION SUNDAY AND STALL NEAR OR JUST A LITTLE SOUTH OF THE OHIO RIVER SUNDAY NIGHT. IN MOST CASES...WENT CLOSE TO A MOS BLEND ON TEMPERATURES AND POPS. A PERIOD OF MIXED PRECIP POSSIBLE ACROSS OUR NORTH MAINLY LATE SUNDAY NIGHT AS TEMPERATURES AND THICKNESSES DROP NEAR CRITICAL VALUES. OTHERWISE...PRECIP ALL RAIN OTHER PERIODS. && .LONG TERM /MONDAY THROUGH FRIDAY/... THE MAIN FOCUS IS COMPRISED OF PRECIP CHANCES AT THE BEGINNING OF THE EXTENDED PERIOD IN REGARD TO A STATIONARY FRONT OVER THE TENNESSEE VALLEY...AND THE NEXT UPPER LEVEL LOW AT THE END OF THE PERIOD. THE EXTENDED STARTS OUT WITH A COLD FRONT LINGERING AROUND THE OHIO RIVER ON MONDAY...AND MODELS SEEM TO BE IN AGREEMENT WITH THIS. SO...WILL STAY WITH INITIALIZATION NUMBERS...WHICH PUT THE HIGHEST POPS ACROSS THE SOUTHERN PORTIONS OF CENTRAL INDIANA THROUGH MONDAY NIGHT. THE NEXT PART OF THE EXTENDED FORECAST BECOMES MORE NEBULOUS. GFS AND EURO CONTINUE TO BE IN DISAGREEMENT IN REGARD TO APPROACHING UPPER LEVEL LOW. THE AGREEMENT IN TIMING BETWEEN THE 2 MODELS SEEMS EVEN WORSE THAN YESTERDAY WITH THE GFS SPEEDING THE TROUGH UP EVEN MORE. THE GFS IS SHOWING THE DEEP UPPER LOW OVER THE UPPER MIDWEST BY TUESDAY AFTERNOON...WHILE THE EURO HAS IT FORMING INTO A CUT-OFF LOW OVER THE SOUTHERN PLAINS. BY THE TIME THE EURO HAS THE LOW IN THE MIDWEST ON WEDNESDAY AFTERNOON THE GFS ALREADY HAS IT OVER LAKE ONTARIO. IN ADDITION...THE GFS IS SHOWING A DEEP CUT-OFF LOW OVER THE LOWER MISSISSIPPI VALLEY BEHIND THE INITIAL WAVE...WHEREAS THE EURO ONLY HINTS AT IT. OF THE 2 MODELS...THE INITIALIZATION NUMBERS CONTINUE TO FAVOR THE DRIER GFS. AGAIN...THERE IS STILL NOT CONSISTENT ENOUGH TRENDING TO DEVIATE FROM THE INITIALIZATION. && .AVIATION /DISCUSSION FOR THE 02/15Z IND TAF UPDATE/... NO CHANGES NECESSARY FOR THE MOMENT. POSTFRONTAL AREA OF IFR CEILINGS/MVFR VISIBILITIES WILL REQUIRE MONITORING...ESPECIALLY AT LAF/HUF AND PERHAPS AT IND. RUC SOUNDING AT LAF BEGINNING TO LOOK TROUBLESOME FOR THE NEXT FEW HOURS...ALTHOUGH STILL EXPECTING TO ERODE ENOUGH TO AVOID IMPACTING TAF SITES. PREVIOUS DISCUSSION FOLLOWS. MID AND HIGH LEVEL CLOUDS WILL AFFECT TAF SITES THIS MORNING IN WAKE OF A WEAK FRONTAL BOUNDARY...BUT CONDITIONS SHOULD STILL STAY AT VFR CATEGORY. MUCH DRIER AIR WILL QUICKLY FILTER INTO TAF SITES BY EARLY AFTERNOON AS HIGH PRESSURE BUILDS ACROSS THE MIDWEST. SO...VFR CONDITIONS WILL PREVAIL FOR ENTIRE TAF PERIOD. MID LEVEL CLOUDS WILL INCREASE EARLY TOMORROW MORNING AHEAD OF THE NEXT UPPER LEVEL DISTURBANCE...BUT AGAIN VFR CONDITIONS ARE EXPECTED. WINDS WILL SLOWLY VEER TO THE EAST/SOUTHEAST THROUGH THE COURSE OF THIS AFTERNOON BUT WILL REMAIN LIGHT AT 4 TO 8 KTS. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...JH NEAR TERM...JH/SMF SHORT TERM...JH LONG TERM....TDUD AVIATION...TDUD/NIELD
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
928 AM EST FRI DEC 2 2011 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... A WEAKENING COLD FRONT FROM NORTHERN INDIANA TO SOUTHEAST MISSOURI WILL MOVE INTO OUR REGION LATER TODAY AND GRADUALLY DISSIPATE. AN AREA OF HIGH PRESSURE BEHIND THE FRONT WILL DOMINATE OUR WEATHER TONIGHT AND SATURDAY. RAIN WILL SPREAD INTO OUR REGION LATE SATURDAY NIGHT AND SUNDAY AS ANOTHER AND STRONGER COLD FRONT MOVES OUR WAY. SEVERAL MODELS STALL THIS FRONT FROM THE LOWER MISSISSIPPI VALLEY TO OHIO EARLY NEXT WEEK...KEEPING SOUTHERN SECTIONS VERY WET. FARTHER NORTH MIXED PRECIP WILL BE THE RULE AS COLDER AIR SPREADS INTO OUR REGION. FINALLY DRY AND COLD WEATHER WILL BE THE RULE AFTER THE MIDDLE OF NEXT WEEK AS THE FRONT TO OUR EAST MOVES EAST AND HIGH PRESSURE OVER THE ROCKIES BUILDS OUR WAY. && .NEAR TERM /TODAY/... AN EXTENSIVE AREA OF MID CLOUDS ACROSS NORTHERN INDIANA AND CENTRAL ILLINOIS WAS SPREADING INTO OUR REGION THIS MORNING. EARLY ON EXPECT THE NORTHWEST HALF OF OUR REGION TO BE MOSTLY CLOUDY. BUT BY MIDDAY MODELS SHOW QUITE A BIT OF DRYING AS HIGH PRESSURE BUILDS INTO THE GREAT LAKES AND DOWNWARD VERTICAL VELOCITIES OCCUR. MAIN FOCUS WILL BE HOW LONG CLOUDS REMAIN. SLOWED DOWN CLEARING JUST A LITTLE. OTHERWISE...WENT CLOSE TO A MODEL BLEND. VISIBLE SATELLITE YESTERDAY INDICATED A LITTLE REMAINING SNOW COVER ACROSS PARTS OF OUR FAR NORTH AND NORTHEAST WHICH MAY HOLD TEMPERATURES DOWN THERE JUST A LITTLE. OTHERWISE...WENT NEAR A MAV/MET BLEND ON TEMPERATURES MOST OTHER AREAS TODAY. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... MODELS ARE IN GOOD AGREEMENT THIS PERIOD SO USED A BLEND WITH ONLY MINOR ADJUSTMENTS. SATURDAY WILL BE MILD AND DRY AS A SOUTHERLY FLOW INCREASES ACROSS OUR REGION AS THE RESULT OF HIGH PRESSURE OVER THE EASTERN U.S. AND LOW PRESSURE MOVING FROM THE CENTRAL PLAINS TOWARDS THE GREAT LAKES. MODELS THIS RUN ARE A TAD SLOWER IN BEGINNING PRECIP MAINLY LATE SATURDAY NIGHT AND MAINTAINING IT A LITTLE FARTHER NORTH SUNDAY AND SUNDAY NIGHT. A COLD FRONT WILL MOVE EAST ACROSS OUR REGION SUNDAY AND STALL NEAR OR JUST A LITTLE SOUTH OF THE OHIO RIVER SUNDAY NIGHT. IN MOST CASES...WENT CLOSE TO A MOS BLEND ON TEMPERATURES AND POPS. A PERIOD OF MIXED PRECIP POSSIBLE ACROSS OUR NORTH MAINLY LATE SUNDAY NIGHT AS TEMPERATURES AND THICKNESSES DROP NEAR CRITICAL VALUES. OTHERWISE...PRECIP ALL RAIN OTHER PERIODS. && .LONG TERM /MONDAY THROUGH FRIDAY/... THE MAIN FOCUS IS COMPRISED OF PRECIP CHANCES AT THE BEGINNING OF THE EXTENDED PERIOD IN REGARD TO A STATIONARY FRONT OVER THE TENNESSEE VALLEY...AND THE NEXT UPPER LEVEL LOW AT THE END OF THE PERIOD. THE EXTENDED STARTS OUT WITH A COLD FRONT LINGERING AROUND THE OHIO RIVER ON MONDAY...AND MODELS SEEM TO BE IN AGREEMENT WITH THIS. SO...WILL STAY WITH INITIALIZATION NUMBERS...WHICH PUT THE HIGHEST POPS ACROSS THE SOUTHERN PORTIONS OF CENTRAL INDIANA THROUGH MONDAY NIGHT. THE NEXT PART OF THE EXTENDED FORECAST BECOMES MORE NEBULOUS. GFS AND EURO CONTINUE TO BE IN DISAGREEMENT IN REGARD TO APPROACHING UPPER LEVEL LOW. THE AGREEMENT IN TIMING BETWEEN THE 2 MODELS SEEMS EVEN WORSE THAN YESTERDAY WITH THE GFS SPEEDING THE TROUGH UP EVEN MORE. THE GFS IS SHOWING THE DEEP UPPER LOW OVER THE UPPER MIDWEST BY TUESDAY AFTERNOON...WHILE THE EURO HAS IT FORMING INTO A CUT-OFF LOW OVER THE SOUTHERN PLAINS. BY THE TIME THE EURO HAS THE LOW IN THE MIDWEST ON WEDNESDAY AFTERNOON THE GFS ALREADY HAS IT OVER LAKE ONTARIO. IN ADDITION...THE GFS IS SHOWING A DEEP CUT-OFF LOW OVER THE LOWER MISSISSIPPI VALLEY BEHIND THE INITIAL WAVE...WHEREAS THE EURO ONLY HINTS AT IT. OF THE 2 MODELS...THE INITIALIZATION NUMBERS CONTINUE TO FAVOR THE DRIER GFS. AGAIN...THERE IS STILL NOT CONSISTENT ENOUGH TRENDING TO DEVIATE FROM THE INITIALIZATION. && .AVIATION /DISCUSSION FOR THE 02/15Z IND TAF UPDATE/... NO CHANGES NECESSARY FOR THE MOMENT. POSTFRONTAL AREA OF IFR CEILINGS/MVFR VISIBILITIES WILL REQUIRE MONITORING...ESPECIALLY AT LAF/HUF AND PERHAPS AT IND. RUC SOUNDING AT LAF BEGINNING TO LOOK TROUBLESOME FOR THE NEXT FEW HOURS...ALTHOUGH STILL EXPECTING TO ERODE ENOUGH TO AVOID IMPACTING TAF SITES. PREVIOUS DISCUSSION FOLLOWS. MID AND HIGH LEVEL CLOUDS WILL AFFECT TAF SITES THIS MORNING IN WAKE OF A WEAK FRONTAL BOUNDARY...BUT CONDITIONS SHOULD STILL STAY AT VFR CATEGORY. MUCH DRIER AIR WILL QUICKLY FILTER INTO TAF SITES BY EARLY AFTERNOON AS HIGH PRESSURE BUILDS ACROSS THE MIDWEST. SO...VFR CONDITIONS WILL PREVAIL FOR ENTIRE TAF PERIOD. MID LEVEL CLOUDS WILL INCREASE EARLY TOMORROW MORNING AHEAD OF THE NEXT UPPER LEVEL DISTURBANCE...BUT AGAIN VFR CONDITIONS ARE EXPECTED. WINDS WILL SLOWLY VEER TO THE EAST/SOUTHEAST THROUGH THE COURSE OF THIS AFTERNOON BUT WILL REMAIN LIGHT AT 4 TO 8 KTS. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...JH NEAR TERM...JH SHORT TERM...JH LONG TERM....TDUD AVIATION...TDUD/NIELD
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
600 PM CST SAT DEC 3 2011 .AVIATION... MVFR/VFR CONDITIONS EARLY THIS EVENING WILL DETERIORATE AS A SURFACE LOW MOVES FROM NORTHWEST MO THROUGH EASTERN IA BY 06Z. CID/DBQ WILL BE NEAR THE CENTER OF THE LOW AND SHOULD EXPERIENCE THE LOWEST CONDITIONS WITH CIGS BLO 5HND FT AND VSBYS AROUND 2SM OR LESS IN RA/BR. AFTER MIDNIGHT AS THE LOW PULLS AWAY FROM THE AREA CONDITIONS WILL GRADUALLY IMPROVE WITH WINDS BECOMING WEST AND THEN NORTHWEST. THE RAIN WILL BE ENDING OVER THE AREA BETWEEN 08Z AND 12Z. CID/DBQ COULD SEE THE PRECIPITATION CHANGE TO SNOW BRIEFLY BEFORE ENDING. AFTER 12Z EXPECT MVFR CIGS WITH VSBYS IMPROVING TO 6SM OR BETTER BY LATE MORNING. ..DLF.. && .PREV DISCUSSION... /ISSUED 308 PM CST SAT DEC 3 2011/ SYNOPSIS... MAIN FEATURE OF INTEREST IS THE UPPER LEVEL LOW OVER LAS VEGAS WITH A LEAD WAVE EJECTING OVER WESTERN KANSAS AT 18Z. MEANWHILE... SURFACE LOW IS LOCATED IN SOUTH-CENTRAL KANSAS WITH THE COLD FRONT EXTENDING NORTH TO FORT DODGE /KFOD/ AND THE UPPER PENINSULA. TEMPS BEHIND THE FRONT DIVE FROM THE MID AND SOME UPPER 40S INTO THE LOWER 30S. LARGE AREA OF RAIN IN THE WARM SECTOR LIFTED NORTH TODAY WITH PRECIP AMOUNTS TYPICALLY IN THE ONE HALF TO ONE INCH RANGE. NEXT ROUND OF PRECIP ASSOCIATED WITH THE MAIN COLD FRONT NOW SPANNING CENTRAL IOWA AND MUCH OF MISSOURI. SHORT TERM...TONIGHT AND SUNDAY... MAIN FORECAST CONCERN TONIGHT IS THE BEHAVIOR OF THE NEXT ROUND OF PRECIP. RUC BRINGS THE SURFACE LOW OVER VINTON /KVTI/ BY 03Z THIS EVENING. THIS IS SLIGHTLY FASTER AND FARTHER NORTHWEST THAN MODEL FORECASTS HAD BEEN BUT IS IN LINE WITH THE OVERALL TREND TO A WARMER FORECAST. IN TERMS OF PRECIP...THIS MORE WESTERN TRACK...AS SEEN IN THE RUC AND CURRENT RADAR TRENDS...SUGGESTS RAIN THROUGH THE EVENING WITH ONLY A BRIEF CHANGE TO SNOW IN THE FAR NORTHERN COUNTIES BEFORE PRECIP ENDS LATE TONIGHT/EARLY SUNDAY MORNING. MUCH OF THE AREA TO BE DRY-SLOTTED OVERNIGHT WITH ONLY THE NORTHERN AND WESTERN SECTIONS EXPECTED TO SEE WRAP-AROUND PRECIP AS THE LOW RACES OFF TO THE NORTHEAST. EVEN SO...BUFKIT SOUNDINGS FOR KCID AND KDBQ LIMIT ANY FROZEN PRECIP TO ONLY AN HOUR OR TWO BEFORE ENDING ALTOGETHER. THUS HAVE REDUCED SNOW AMOUNTS AND ENDED PRECIP A FEW HOURS EARLIER THAN PREVIOUS FORECAST. ..DMD.. LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY HIGH PRESSURE AT THE SURFACE MIGRATING THROUGH THE NORTHERN PLAINS INTO THE UPPER MS VALLEY TO BRING NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES FROM SUNDAY NIGHT THROUGH WEDNESDAY. THROUGH THIS PERIOD...MODELS IN GENERAL AGREEMENT FEATURING AN UPPER LEVEL POSITIVE TILT LONG WAVE TROUGH TRANSITIONING EAST THROUGH THE CENTRAL U.S....SUPPRESSING THE MAIN BAROCLINIC AXIS AND STORM TRACK WELL TO THE SOUTHEAST. A WAVE OF LOW PRESSURE TRACKING ALONG THE OHIO RIVER MONDAY WILL SPREAD SNOW INTO PORTIONS OF MO AND IL...AND WILL KEEP ONLY SLIGHT CHANCE POPS CONFINED TO THE FAR EAST AND SOUTH MONDAY NIGHT ON THE EXTREME NW EDGE OF THIS SYSTEM. OTHERWISE...NO PRECIPITATION IS EXPECTED...BUT HIGH LEVEL LIFT AND MOISTURE ALOFT AHEAD OF THE UPPER TROUGH AXIS WILL FAVOR MOSTLY CLOUDY SKIES FOR MUCH OF MON THROUGH WED. THU THROUGH SAT...MODEL CONSENSUS INDICATES A COLD FRONT DROPPING SOUTH THROUGH THE REGION LATE THURSDAY...FOLLOWED BY MUCH COLDER TEMPERATURES FRIDAY AND SATURDAY FOLLOWING A FRESH INFLUX OF COLD AIR AT 850 MB THAT HAS BEEN BUILDING WELL TO THE NORTH. THERE CONTINUES TO BE CONSIDERABLE DIFFERENCES WITH THE TIMING AND PLACEMENT OF CRITICAL UPPER LEVEL TROUGHS AND SURFACE FEATURES IN THIS TIME FRAME...THUS THE POTENTIAL FOR PRECIPITATION REMAINS LOW CONFIDENCE. THE CURRENT SUITE OF MODELS USED IN THE EXTENDED SUPPORTS OUR SLIGHT TO LOW END CHANCES FOR LIGHT SNOW FOR THU NIGHT FOLLOWING THE PASSAGE OF THE COLD FRONT. AHEAD OF THIS FRONT...HIGHS THURSDAY SHOULD REACH INTO THE 30S IN MOST AREAS. THIS IS FOLLOWED BY 20S FRIDAY AND SATURDAY WITH OVERNIGHT LOWS IN THE SINGLE DIGITS AND TEENS. ..SHEETS.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1220 AM EST FRI DEC 2 2011 .SYNOPSIS... HIGH PRESSURE BUILDS INTO THE MID ATLANTIC REGION FROM THE WEST TONIGHT THROUGH WEEKEND. A WEAK...DRY COLD FRONT WILL CROSS INTO THE AREA FRIDAY NIGHT...BRINGING SLIGHTLY COOLER TEMPERATURES SATURDAY. MILDER CONDITIONS RETURN FOR THE LATTER HALF OF THE WEEKEND INTO EARLY NEXT WEEK AHEAD OF A SLOW MOVING COLD FRONT...WHICH APPROACHES THE REGION FROM THE WEST BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TODAY/... LATEST WX ANALYSIS DEPICTS ~1028MB SURFACE HIGH PRESSURE OVER E KY/TN. ALOFT...TROUGH-RIDGE-TROUGH PATTERN EVIDENT ON RUC H5 ANALYSIS AS MID LEVEL TROUGHING HAS NOW TRANSITIONED OFF THE EAST COAST...WITH LOW AMPLITUDE H5 RIDGING TO THE WEST OVER THE GULF COAST/LOWER MS VALLEY...WITH CLOSED OFF/POSITIVELY TILTED UPPER LEVEL LOW PRESSURE REMAINS IN PLACE OVER BAJA/SOUTHERN CALIFORNIA. BREEZY CONDITIONS STILL IN PLACE OVER MAINLY COASTAL ZONES THIS AFTERNOON AS A RESULT OF PRESSURE GRADIENT BETWEEN DEPARTING MID LEVEL TROUGH...AND HIGH PRESSURE TO THE WEST. COASTAL AREAS SHOULD CONTINUE TO BE BREEZY (GUSTS TO 15-17 KT) FOR A FEW MORE HOURS BEFORE DECOUPLING/RELAXING PRESSURE GRADIENT ALLOWS FOR WINDS TO DROP OFF EARLY THIS EVENING. OTHERWISE...A MOSTLY CLEAR AND PLEASANT LATE FALL AFTERNOON ACROSS THE CWA...MAXIMA WL AVERAGE OUT INTO THE MID 50S INLAND...LOW TO MID 50S OVER COASTAL ZONES. CLEAR SKIES/LIGHT WINDS PORTEND TO GOOD RADIATING CONDITIONS TONIGHT. LOOKING FOR TEMPERATURES BE CLOSE TO/JUST BELOW LAST NIGHTS/THIS MORNING`S LOWS. LOOK FOR LOWS INTO THE M-U 20S INLAND...LOW TO MID 30S OVER COASTAL ZONES. && .SHORT TERM /TONIGHT THROUGH SUNDAY/... LATE WEEK/WEEKEND TIME FRAME CHARACTERIZED BY SLOWLY BUILDING UPPER LEVEL RIDGING WITH TIME OVER THE EASTERN CONUS...RESULTING IN CONTINUED DRY WEATHER THROUGH THE PERIOD. FRIDAY... HIGH PRESSURE BECOMES ENTRENCHED OVER THE MID ATLANTIC STATES THROUGH THE WEEKEND. AS A CUTOFF LOW DEVELOPS OVER THE SOUTHWESTERN US...A WEAK UPPER LEVEL TROUGH WILL BECOME SEPARATED FROM IT AND DRIFT ACROSS THE NORTHERN PLAINS/UPPER GREAT LAKES...BEFORE SLOWLY PUSHING ACROSS NEW ENGLAND BY FRIDAY NIGHT. THIS FEATURE WILL EVENTUALLY PUSH WEAK/DRY FRONTAL BOUNDARY TO OUR NORTH THROUGH THE REGION LATE TOMORROW INTO SATURDAY WITH LITTLE MORE THAN A FEW MID-HIGH CLOUDS PUSHING ACROSS THE AREA. MAXIMA SLIGHTLY WARMER THAN TODAY`S VALUES...GENERALLY INTO THE M/U 50S AREA WIDE...NEAR 60 WELL INLAND. SO WHILE WE CAN EXPECT A SLIGHTLY MILDER EVENING FRIDAY NIGHT...HAVE SIDED CLOSER TO COOLER ENVELOPE OF MAV GUIDANCE IN EXPECTATION OF LIGHT WINDS OVER LAND AND STILL RELATIVELY SCANT MID LEVEL CLOUD COVER AS HIGH PRESSURE SLIDES OVERHEAD. EARLY MORNING LOWS FRI NIGHT/SAT MORNING GENERALLY INTO THE L-M30S TO NEAR 40 ALONG COASTAL ZONES. SATURDAY... THE SURFACE HIGH BECOMES POSITIVELY TILTED ON SATURDAY AS THE RIDGE AXIS BEGINS TO SHIFT OFFSHORE. DESPITE AFOREMENTIONED WARMING WITH TIME ALOFT AS SUBTROPICAL RIDGE BEGINS TO BUILD ACROSS THE SOUTHEASTERN CONUS...TEMPERATURES WILL BE MODESTLY COOLER SATURDAY DUE TO THE INFLUENCE OF MODIFYING ~1036MB SFC HIGH PRESSURE PUSHING IN FROM THE WEST. AS WE`VE SEEN SEVERAL TIMES ALREADY THIS FALL...LIMITED MIXING NOTED ON FORECAST SOUNDINGS FOR SATURDAY (GENERALLY TO ~950-925MB) WILL KEEP TEMPERATURES A BIT LOWER THAN LOCAL THICKNESS TOOLS AND WARMER MAV GUIDANCE DEPICT. AS SUCH...HAVE GONE CLOSER TO COOLER MET VALUES FOR MAXIMA ON SATURDAY WHICH YIELD SEASONABLE...ALBEIT SLIGHTLY COOLER...MAXIMA INTO THE LOW TO MID 50S. SATURDAY NIGHT/SUNDAY... SURFACE HIGH PIVOTS TO THE MID-ATLANTIC/SE COAST AND THEN OFFSHORE SAT NIGHT THROUGH SUNDAY...WITH DEVELOPING RETURN (SOUTH- SOUTHEAST) FLOW AND CONTINUED BUILDING OF RIDGING ALOFT INITIATING MODERATING TEMPERATURE TREND FOR SATURDAY NIGHT THROUGH THE EARLY PORTION OF NEXT WEEK. LOOK FOR EARLY MORNING LOWS CONTINUED DRY AND MILDER CONDITIONS SUNDAY WITH MAXIMA INTO THE L-M 60S. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... OVERALL PATTERN IN THE EXTENDED FAVORS A DOMINANT MID/UPPER LEVEL RIDGE CENTERED FROM THE GULF OF MEXICO ENE ACRS FLORIDA AND TOWARDS BERMUDA. MEANWHILE...A DEEP TROUGH OVER CENTRAL CANADA WILL GRADUALLY PUSH SOUTH AND TAKE ON A POSITIVE TILT (OR EVEN BECOME CUTOFF) OVER THE CENTRAL CONUS. THIS SETUP WILL BE VERY SLOW TO CHANGE THROUGH THE MIDDLE OF NEXT WEEK...AND WILL KEEP BULK OF PRECIPITATION OFF TO OUR WEST UNTIL WED. FOR THE MID ATLC AND SE STATES...THIS WILL ALSO TRANSLATE INTO WELL ABOVE AVG TEMPERATURES MON-TUE...AND POSSIBLY WED BEFORE COOLING DOWN TO AROUND AVG ON THU. GIVEN THE CONTINUED MODEL DISCREPANCIES (LATEST ECMWF REMAINING ABOUT 12-18 HRS SLOWER THAN THE GFS/GLOBAL GEM ENSEMBLES....CONFIDENCE IN TUE-THU FCST IS LOWER THAN AVG. AS WITH PREVIOUS FCST...HAVE GENLY BROAD-BRUSHED A LOW CHANCE POP ACRS THE NW ZONES...TO DRY OR SLIGHT CHANCE ELSEWHERE FROM LATE MON THROUGH TUE. WILL FOCUS HIGHEST POPS DURING THE DAY WED/WED EVENING AS A BLEND OF MODEL TIMING PUSHES THE SFC COLD FRONT THROUGH. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... VFR UFN AS HIGH PRES KEEPS SKIES CLEAR THRU FCST PERIOD. A DRY FRONTAL BOUNDARY CROSSES THE AREA TONITE SHIFTING WINDS INTO THE N-NE. VFR CONDITIONS CONT THRU THE WEEKEND. && .MARINE... NO FLAGS NEXT 12-18 HRS AS HIGH PRS BUILDS OVR THE WATERS KEEPING CNDTNS BELOW SCA LVLS. PVS DSCN: ANOTHER BOUNDARY/COOL SURGE FRI NIGHT...WITH MARGINAL SCA EVENT LIKELY ONCE AGAIN OVER THE BAY....AND POSSIBLE ON THE COASTAL WATERS. AS THIS IS LATER 3RD PERIOD...HAVE DECIDED TO WAIT UNTIL CURRENT HEADLINES END BEFORE RAISING ANOTHER SET (ALTHOUGH FCST DOES INCLUDE SCA CONDITIONS). THIS SURGE IS FAIRLY BRIEF...AND SHOULD END BY LATE SAT MORNING ASIDE FROM LINGERING 5 FT SEAS OVER SOUTHERN COASTAL WATERS. OTHERWISE...BENIGN SAT EVENING THROUGH MON AS HIGH PRESSURE SETTLES OVER THE REGION AHEAD OF THE NEXT COLD FRONT. WINDS GRADUALLY TURN SOUTHERLY SUN-TUE BUT WIND SPEEDS LOOK TO AVG 10-15 KT OR LESS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...MAM NEAR TERM...BKH/MAM SHORT TERM...MAM/BMD LONG TERM...LKB AVIATION...MPR MARINE...MPR/LKB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
440 AM EST FRI DEC 2 2011 .DISCUSSION... A COLD MORNING WHERE IT HAS CLEARED OUT OVERNIGHT WITH MANY INTERIOR SPOTS SEEING TEMPS IN THE SINGLE DIGITS UNDER HIGH PRESSURE AND LOW PRECIPITABLE WATER VALUES OF AROUND 0.1 INCH. WOULD NOT BE SURPRISED IF WE SEE A FEW TEMPS NEAR 0F NEAR THE WISCONSIN BORDER WITH DWPTS JUST ABOVE 0 AT THIS TIME. LAKE EFFECT CLOUDS ARE STARTING TO RETREAT TO THE NORTH AND EAST AS HIGH PRESSURE RIDGING ACROSS THE UPPER MS VLY BUILDS ACROSS THE AREA. EXPECT ANY REMAINING CLOUDS AND FLURRIES TO CLEAR OUT THIS MORNING YIELDING A MOSTLY SUNNY DAY ACROSS THE AREA. UPPER HEIGHTS BUILD RATHER QUICKLY TODAY WITH RATHER ABRUPT WARM ADVECTION DEVELOPING THIS AFTERNOON AS THE WESTERN TROUGH SHIFTS EAST. IN FACT...BY 00Z THIS EVENING 850MB TEMPS RISE TO -2C ACROSS THE WEST /FROM -12C THIS MORNING/. SHOULD SEE A NICE RECOVERY IN TEMPS TODAY WITH ALL AREAS WELL INTO THE UPPER 20S. DEVELOPING DOWNSLOPE S-SW FLOW THIS AFTN MAY HELP TEMPS NEAR THE LAKESHORE TOP OUT IN THE LOWER 30S. THE FORECAST BEGINS TO BECOME TRICKY STARTING LATER TONIGHT AND CONTINUES TRICKY RIGHT THROUGH SUNDAY. STRONG SHORT WAVE ENERGY CURRENTLY OVER BRITISH COLUMBIA WILL DIVE SOUTHEASTWARD TODAY. THIS WILL CAUSE AN ALBERTA CLIPPER LIKE SYSTEM TO MOVE ACROSS THE UPPER LAKES SATURDAY. A PIECE OF ENERGY WILL ALSO BREAK OFF FROM THIS WAVE...DIVING DUE SOUTH DOWN THE INTERMOUNTAIN WEST HELPING TO EJECT THE DEEP UPPER LOW OVER THE SOUTHWESTERN STATES TONIGHT INTO SATURDAY. AS THE FRONT ASSOCIATED WITH THE NORTHERN LOW MOVES ACROSS THE UPPER GREAT LAKES...GULF MOISTURE WILL STREAM NORTHWARD ALONG THE FRONT ON SATURDAY. ALTHOUGH SYNOPTIC FORCING NOT BE TERRIBLY STRONG...THERE WEAK ISENTROPIC LIFT DURING THE DAY ON SATURDAY SHOULD ALLOW FOR LIGHT PRECIPITATION TO FALL ALONG AND EAST OF THE FRONT. WITH THIS BEING SAID...HAVE OPTED TO MAINTAIN LIKELY POPS DURING THE DAY ACROSS THE EASTERN HALF OF THE FORECAST AREA...WITH A MINIMAL CHANCE FOR PRECIPITATION ACROSS WESTERN UPPER MICHIGAN WHERE DRIER AIR AND MINIMAL ISENTROPIC LIFT WILL MINIMIZE ANY PCPN CHANCES. AS FOR PRECIPITATION TYPE ON SATURDAY...EXPECT MOSTLY SNOW TO FALL EXCEPT FOR AREAS CLOSE TO LAKE MICHIGAN WHERE BOUNDARY TEMPS WITH SOUTHERLY FLOW SHOULD RISE ENOUGH TO KEEP IT ALL RAIN OR A RAIN/SNOW MIX. WITH LACK OF SIGNIFICANT UPWARD MOTION...DO NOT EXPECT ACCUMULATIONS TO AMOUNT TO MORE THAN AN INCH OR TWO WHERE IT DOES SNOW THE LONGEST. ALTHOUGH MODELS HAVE COME INTO BETTER AGREEMENT IN BRINGING A SURFACE LOW ACROSS THE UPPER LAKES SATURDAY NIGHT INTO SUNDAY...THERE ARE STILL SUBTLE DETAILS WHICH WILL MAKE THE SNOWFALL FORECAST CHALLENGING. OVERALL...THE LOW TRACK IS BECOMING BETTER DEFINED WITH A TRACK ACROSS LAKE MICHIGAN AND TO FAR EASTERN UPPER MI BY SUN MORNING. IN ADDITION...WITH THE EXCEPTION OF THE GFS...THE MODELS HAVE ALSO COME INTO BETTER AGREEMENT IN SHOWING A SWATH OF MODERATE PRECIPITATION IN THE FORM OF SNOW TO MOVE ACROSS CENTRAL UPPER MICHIGAN SAT NIGHT INTO SUNDAY MORNING DURING THE PERIOD OF BEST FRONTOGENETIC FORCING COMBINED WITH REDUCED STABILITY ALOFT. WITH THE EXCEPTION OF THE GFS...THE OTHER MODELS ARE IN FAIRLY GOOD AGREEMENT IN SHOWING A SWATH OF .75 INCH OF PRECIPITATION SAT NIGHT INTO SUNDAY MORNING. THIS MAKES SENSE GIVEN THE TRACK OF THE SFC AND 850MB LOW COMBINED WITH PRECIPITABLE WATER VALUES AROUND 0.5 INCH. WITH THAT BEING SAID...HAVE RAISED POPS TO CATEGORICAL FOR THE EASTERN PART OF THE FORECAST AREA SAT NIGHT INTO SUNDAY AND HAVE GONE WITH STORM TOTAL SNOWFALL SAT NIGHT INTO SUNDAY OF 5-8 INCHES MAINLY EAST OF A LANSE TO IRON RIVER LINE. DEPENDING ON THE EXACT TRACK...MAY SEE SOME PRECIPITATION TYPE CONCERNS ACROSS EASTERN UPPER AS WELL AS NEAR LAKE MICHIGAN...BUT ONLY IF THE NAM FORECAST TRACK VERIFIES. ORIGINALLY WAS THINKING ABOUT GOING WITH A WINTER STORM WATCH FOR PARTS OF CENTRAL UPPER MICHIGAN...BUT OPTED TO HOLD OFF GIVEN THAT THE HEAVIEST SNOW WILL OCCUR AT NIGHT AND THE FACT THAT THE STORM WILL MOVE THROUGH RATHER QUICKLY. STILL...FORECAST AMOUNTS ARE VERY CLOSE TO WARNING CRITERIA AND GIVEN THAT THE SNOW WILL BE WET IN NATURE /GENERALLY A 12-15:1 RATIO/...A WINTER STORM WATCH MAY NEED TO BE ISSUED THIS AFTERNOON. LES EXPECTED SUNDAY NIGHT...HOWEVER THE INTENSITY AND PLACEMENT WILL DEPEND ON WHETHER ANOTHER WEAK LOW MOVES INTO THE AREA IN THE NW FLOW AS THE GEM AND GFS SUGGEST. FOR NOW...HAVE OPTED TO GO WITH CHC POPS NEAR THE LAKESHORE WITH THE HIGHEST POPS WEST. FOR THE EXTENDED /MONDAY THROUGH THURSDAY/... WITH SFC HIGH PRESSURE PUSHING IN FROM THE W AND A SFC TROUGH EXTENDING FROM THE E OVER LAKE SUPERIOR...LOW LEVEL WINDS WILL GENERALLY BE NW. AN UPPER TROUGH AXIS FROM FAR NERN CANADA TO THE FAR SWRN CONUS WILL MOVE OVER THE CWA LATE MONDAY INTO TUESDAY. COOL 850MB TEMPS AOB -10C WILL EXIST UNDER THE TROUGH. THIS WILL RESULT IN LAKE EFFECT SNOW IN NW WIND SNOWBELTS. THE BEST CHANCES FOR SNOW WILL BE MONDAY...SINCE HIGH PRESSURE AND DRIER AIR WILL MOVE IN FROM THE W MONDAY NIGHT. THE SFC HIGH PRESSURE RIDGE WILL THEN PUSH EAST OF THE CWA LATE TUESDAY...LEADING TO SW WINDS AHEAD OF A TROUGH OVER THE NRN PLAINS. WITH THE SW WINDS AND 850MB TEMPS AOA -8C WED NIGHT...NO LAKE EFFECT PRECIP IS EXPECTED. WED WILL SEE BIG PATTERN CHANGES AS THE SFC TROUGH AND STRONG COLD FRONT PASS THROUGH THE CWA. THE COOLEST AIR OF THE SEASON IS INDICATED BY MODELS TO MOVE OVER THE AREA AS A DEEP LOW MOVE S TO HUDSON BAY. THIS WILL BRING A DEEP...BROAD TROUGH ACROSS MOST OF THE NRN CONUS WED AND THU. BEHIND THE SFC TROUGH...LOW LEVEL WINDS WILL BE FROM THE NW AS 850MB TEMPS FALL TO AROUND -20C BY 06Z THU...AND LOW LEVEL RH PLENTY SUFFICIENT FOR LAKE EFFECT PRECIP. && .AVIATION /FOR 06Z TAF ISSUANCE/ WITH 900 MB TEMPS NEAR -11C...THERE IS CURRENTLY ENOUGH INSTABILITY TO SUSTAIN LAKE CLOUDS. RUC 925-900 MB RH FCST AND RECENT TRENDS SUGGEST THAT CLEARING WILL BE SLOW TO ADVANCE THIS EVENING...KEEPING KIWD/KCMX NEAR THE EDGE OF THE CLOUD AREA. VFR CONDITIONS SHOULD THEN PREVAIL THE REST OF THE NIGHT INTO FRI. && .MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/... A HIGH PRESSURE RIDGE OVER LAKE SUPERIOR WILL KEEP CONDITIONS ON THE LAKE QUIET OVERNIGHT...WITH FLOW BEING GENERALLY NORTHWEST. THE RIDGE WILL MOVE OUT BY THIS AFTERNOON. A LOW PRESSURE SYSTEM CENTERED OVER MANITOBA WILL MOVE TO HUDSON BAY BY SATURDAY...DRAGGING A TROUGH AND COLD FRONT ACROSS LAKE SUPERIOR LATE SATURDAY. BETWEEN THE TWO SYSTEMS...THE PRESSURE GRADIENT WILL STRENGTHEN. AS A RESULT...GALES TO 35-40 KNOTS ARE EXPECTED ON THE LAKE FROM FRIDAY THROUGH SATURDAY MORNING. WESTERN LAKE SUPERIOR WILL SEE THE START OF THE GALES FRIDAY AFTERNOON...AND ON FRIDAY NIGHT THE EASTERN ZONES. ALL OF THE GALE FORCE WINDS SHOULD END SATURDAY MORNING. WINDS WILL CONTINUE TO GUST TO AROUND 30 KNOTS SATURDAY AFTERNOON...BEFORE DECREASING TO LESS THAN 25 KNOTS FOR THE REMAINDER OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... GALE WARNING FROM 7 PM THIS EVENING TO 10 AM EST SATURDAY FOR LSZ266-267. GALE WARNING FROM 10 AM EST /9 AM CST/ THIS MORNING TO 7 AM EST /6 AM CST/ SATURDAY FOR LSZ162-263-264. LAKE MICHIGAN... NONE. && $$ DISCUSSION...MRD EXTENDED...TITUS AVIATION...TITUS MARINE...TITUS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1239 AM EST FRI DEC 2 2011 UPDATED AVIATION DISCUSSION FOR 06Z TAFS .SHORT TERM... FOR TONIGHT...LOW PRESSURE TROUGH RESPONSIBLE FOR LAST NIGHT AND TODAYS SNOWFALL WILL MAKE ITS WAY FROM EASTERN UPPER MICHIGAN TO QUEBEC OVERNIGHT. MEANWHILE...A RIDGE EXTENDING FROM HIGH PRESSURE IN THE CENTRAL PLAINS WILL SETTLE IN OVER UPPER MICHIGAN...BRINGING QUIETER CONDITIONS TO A MAJORITY OF THE CWA. MAIN CONCERN IS WHETHER OR NOT LES WILL CONTINUE TO IMPACT EASTERN UPPER MICHIGAN THROUGH THE NIGHT WITH THE INCOMING DRY AIR. AS OF 15Z...CONDITIONS ACROSS MINNESOTA WERE DRYING OUT...WITH CLEAR SKIES AND LARGE DEWPOINT DEPRESSIONS OBSERVED. 12Z SOUNDINGS AT INTERNATIONAL FALLS MN AND PICKLE LAKE ONTARIO SHOW INVERTED V-TYPE SOUNDINGS...WITH INVERSION HEIGHTS AROUND 3000 FEET. THIS DRYING WITH LOW INVERSION HEIGHTS SUGGESTS THAT ANY LES ACCUMULATIONS OVERNIGHT IN THE EASTERN CWA WILL BE SMALL...AND COVERAGE WILL BE LIMITED. CURRENTLY MOST CLOUD COVER IS DIMINISHING ACROSS THE WESTERN CWA...WITH THE EXCEPTION OF LAKE EFFECT CLOUDS. REGWRF...RUC...AND GFS ALL HINT AT A COUPLE OF LES BANDS DEVELOPING EAST OF MARQUETTE...MOVING TOWARDS GRAND MARAIS AND LASTING THROUGH THE NIGHT. SOME CLOUD BANDS ARE OBSERVED ON THE VISIBLE SATELLITE AT THE MOMENT OVER EASTERN LAKE SUPERIOR...AND I EXPECT THESE TO BECOME MORE ORGANIZED AFTER DARK. THE MAIN DIFFERENCE OBSERVED BETWEEN EACH OF THE MODEL FIELDS IS THE AMOUNT OF LINGERING MOISTURE...THE NAM PUSHES ALL OF THE MOISTURE OUT OF THE REGION BY 00Z TONIGHT...WHICH PUTS THE END TO LES. THIS SEEMS TO BE THE OUTLIER...HOWEVER. WITH THE WINDS OUT OF THE NORTHWEST THIS EVENING...EXPECT SOME LIGHT LAKE EFFECT SNOW SHOWERS TO CONTINUE FROM MARQUETTE MOVING EASTWARD THROUGH THE NIGHT AS THE DRIER AIR WORKS IN. ANOTHER FAVORABLE FACTOR IS THAT LES TYPICALLY RAMPS UP DURING THE NIGHT HOURS...AND AS A RESULT WILL KEEP IN SOME SHOWERS EAST OF MARQUETTE. THIS LES SHOULD END BY EARLY MORNING HOWEVER...AS WINDS BECOME WESTERLY...PUSHING ANY REMAINING BANDS INTO ONTARIO OR ENDING THEM ALL TOGETHER. FOR THE WESTERN CWA ONLY HAVE LAKE INDUCED CLOUD COVER LASTING THROUGH AROUND 6Z AS A RESULT OF THE NORTHWEST WINDS...THEN TAPERING OFF AS THE WINDS SHIFT TO THE SOUTHWEST. CLOUD COVER IN THE INTERIOR WEST TONIGHT...ALLOWING FOR DECENT RADIATIONAL COOLING. AS A RESULT...TEMPERATURES NEAR THE WISCONSIN BORDER SHOULD FALL INTO THE SINGLE DIGITS TONIGHT. AS FOR FRIDAY...WITH THE HIGH PRESSURE RIDGE OVERHEAD AND THE DRY AIRMASS IN PLACE...EXPECT A MOSTLY SUNNY DAY. TEMPERATURES WILL STRUGGLE TO REACH INTO THE 30S INLAND AS A RESULT OF MORE STABLE CONDITIONS. EXPECT WINDS TO INCREASE THROUGHOUT THE DAY AS PRESSURE GRADIENT BETWEEN HIGH PRESSURE RIDGE AND A LOW PRESSURE SYSTEM CENTERED OVER MANITOBA TIGHTENS. .LONG TERM 00Z SAT ONWARD... THE NAM SHOWS A 500 MB SHORTWAVE RIDGE OVER THE UPPER GREAT LAKES 00Z SAT WITH A TROUGH IN THE NORTHERN ROCKIES AND A CLOSED LOW AND TROUGH IN THE DESERT SW 00Z SAT. THE TROUGH PULLS EAST INTO THE NORTHERN PLAINS 00Z SUN WITH THE SOUTHERN TROUGH GETTING CUT OFF AND REMAINING IN THE DESERT SW. NAM SHOWS SOME 850-500 MB Q-VECTOR CONVERGENCE AND MOISTURE SAT INTO SUN MORNING. NAM ALSO SHOWING SOME ISENTROPIC LIFT AND MOISTURE ON I280K-I295K SURFACES ON SAT BEFORE THE LIFT MOVES OFF FOR SAT NIGHT INTO SUNDAY. GFS SHOWS SOME 850-500 MB Q-VECTOR CONVERGENCE MOVING THROUGH FRI NIGHT THROUGH SAT EVENING BEFORE THIS MOVES OUT. STILL LOOKS LIKE A 3-6 INCH SNOW EVENT FOR THE CWA WITH THE MOST SNOW IN THE CENTRAL CWA AND LESSER AMOUNTS IN THE WEST AND EAST. THE EAST WOULD HAVE SOME RAIN MIXED IN AND THE WEST WOULD BE ON THE WESTERN EDGE OF THE PCPN SHIELD. LAKE EFFECT THEN TAKES OVER ON SUNDAY FOR NORTH AFFECTED LAKE EFFECT SNOW BELTS. OVERALL DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST FOR TEMPERATURES OR WEATHER. IN THE EXTENDED...THE GFS AND ECMWF SHOW A 500 MB TROUGH OVER THE NORTHERN PLAINS 00Z MON DOWN INTO THE SOUTHERN ROCKIES. THIS TROUGH MOVES INTO THE UPPER GREAT LAKES 00Z TUE. THIS TROUGH THEN SPLITS WITH THE NORTHERN PART OF THE TROUGH OVER THE LOWER GREAT LAKES WHILE THE SOUTHERN PART IS OVER THE SOUTHERN PLAINS 00Z WED. A BROAD TROUGH THEN SETS UP ACROSS THE NORTHERN U.S. 00Z THU ASSOCIATED WITH THE CIRCUMPOLAR VORTEX OVER CENTRAL AND NORTHERN CANADA WITH THE TROUGH AXIS REMAINING OFF TO THE WEST OF THE AREA 00Z FRI. WHAT THIS WILL MEAN IS COLDER WEATHER IS ON THE WAY WITH LAKE EFFECT SNOW BEING THE MAIN WEATHER TYPE FOR THIS FORECAST AND COLDER THAN NORMAL TEMPERATURES. 850 MB TEMPERATURES GET DOWN TO -14C ON MONDAY INTO TUESDAY WITH THE GFS WITH A WARMUP FOR WED...BEFORE A REINFORCING SHOT OF COLD AIR ARRIVES FOR THU AS A COLD FRONT MOVES THROUGH. OVERALL...DID NOT CHANGE MUCH EXCEPT TO BUMP UP POPS ON THURSDAY IN LAKE EFFECT AREAS WITH THE COLDER AIR. && .AVIATION /FOR 06Z TAF ISSUANCE/ WITH 900 MB TEMPS NEAR -11C...THERE IS CURRENTLY ENOUGH INSTABILITY TO SUSTAIN LAKE CLOUDS. RUC 925-900 MB RH FCST AND RECENT TRENDS SUGGEST THAT CLEARING WILL BE SLOW TO ADVANCE THIS EVENING...KEEPING KIWD/KCMX NEAR THE EDGE OF THE CLOUD AREA. VFR CONDITIONS SHOULD THEN PREVAIL THE REST OF THE NIGHT INTO FRI. && .MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/... HIGH PRESSURE RIDGE OVER LAKE SUPERIOR WILL KEEP CONDITIONS ON THE LAKE QUIET OVERNIGHT...WITH FLOW BEING GENERALLY NORTHWEST. AS THE RIDGE MOVES OUT...A LOW PRESSURE SYSTEM CENTERED OVER MANITOBA WILL DRAG A TROUGH ACROSS LAKE SUPERIOR. AS IT PROGRESSES EASTWARD...THE PRESSURE GRADIENT WILL STRENGTHEN. AS A RESULT...GALES TO 35-40 KNOTS ARE EXPECTED ON THE LAKE FROM FRIDAY THROUGH SATURDAY MORNING. WESTERN LAKE SUPERIOR NEAR ISLE ROYALE AND NORTH CENTRAL LAKE SUPERIOR WILL SEE THE START OF THE GALES FRIDAY AFTERNOON...AND ON FRIDAY NIGHT THE EASTERN ZONES. ALL OF THE GALE FORCE WINDS SHOULD END BY SATURDAY MORNING. WINDS WILL CONTINUE TO GUST TO AROUND 30 KNOTS SATURDAY AFTERNOON...BEFORE DECREASING TO LESS THAN 20 KNOTS FOR THE REMAINDER OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... GALE WARNING FROM 7 PM THIS EVENING TO 10 AM EST SATURDAY FOR LSZ266-267. GALE WARNING FROM 10 AM THIS MORNING TO 7 AM EST SATURDAY FOR LSZ263-264. LAKE MICHIGAN... NONE. && $$ SHORT TERM...MCB LONG TERM...07 AVIATION...TITUS MARINE...MCB
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
604 PM CST SAT DEC 3 2011 .DISCUSSION... SNOW HAS BEGUN TO SRPEAD INTO S MN AND WILL CONTINUE TO EXPAND NE RAPIDLY DURING THE REMAINDER OF THE AFTERNOON. A BIT OF SATURATION LEFT TO DO IN LOWER LEVELS BUT CIGS ARE BEGINNING TO LOWER ACROSS S MN. IR SATELLITE SHOWS ELONGATED VORT FROM W KS INTO SC NEB LIFTING NE. GFS/NAM SIMILAR ON TIMING BRINGING MAIN VORT INTO SC MN BY 00Z AND THEN LIFTING INTO CENTRAL WI BY 06Z. GFS HAS INCREASED QPF VALUES A BIT MORE TOWARD THE NAM SOLUTION. INCREASED SNOW AMOUNTS A BIT ACROSS AREAS FROM MKT TO SE METRO BASED LARGELY ON TRACK OF SURFACE/850 MB LOW CENTERS. HEAVY SNOW OFTEN SETS UP 70 TO 90 MILES N OF 850 MB LOW TRACK..AND 850 MB LOW TRACKS FROM SW IA TO JUST S OF LSE BY 06Z THEN INTO E UPR MICHIGAN BY 12Z. KEPT SNOW AMOUNTS IN THE 3 TO 6 INCH ADVISORY. FAVORABLE ISENTROPIC LIFT COMES THRU RATHER QUICKLY WITH 3-3.5G/KG SO HESITATE TO GO ANY HIGHER. WILL BE A PERIOD FROM AROUND 22Z TO 05Z WHERE ADVISORY AREA WILL BE UNDER STRONG UPPER DIVERENGE FROM COUPLED UPPER JET... FAVORABLE DENDRITIC TEMPERATURES AND STRONG 600 MB FULL WIND FRONTOGENSIS WHICH COULD BRING A PERIOD OF A FEW HOURS OF VISIBILITY INTO THE 1/2 SM RANGE AS FAR N AS MSP. LIKE THE TIMING OF THE RUC BUFKIT SNOW ACCUMS IN THAT WINDOW. DECREASED SNOW AMOUNTS SLIGHTLY IN W SIDE OF ADVY AREA AROUND SPRINGFIELD AND GAYLORD. ADVISORY WILL LIKELY BE ABLE TO BE EXPIRED BY 06Z ACROSS MUCH OF THE MN CWA WITH NO SIGNIFICANT WIND EXPECTED IN WAKE OF SNOW. COOLER FOR SUNDAY...BUT TROF DROPPING OUT OF CANADA WILL BACK WINDS ENUF TO KEEP MAIN PUSH OF COLD AIR NORTH OF AREA. AS THIS SYSTEM MOVES THRU COLD AIR WILL MOVE IN FOR MONDAY WITH HIGHS ONLY IN THE TEEN TO MID 20S. SLIGHT MODERATION FOR WEDNESDAY AS WEAK TROF MOVES ACROSS AREAK. AFTER THAT AREA REMAINS IN COLD AND DRY NW FLOW AT LEAST UNTIL NEXT WEEKEND. WITH SNOW COVER EXPECTED TONIGHT ACROSS S MN INTO WC WI WILL BE SOME SOME MORNINGS WHERE WE SHOULD GET MIN TEMPS DOWN NEAR ZERO...TUESDAY AND PROBABLY AGAIN FRIDAY/SATURDAY. .AVIATION.../00Z TAF ISSUANCE/ MAIN FORCING FOR SNOW WILL CONTINUE THROUGH EVENING FROM KMSP TO THE EAST. KRNH TO KEAU LIKELY TO BE LIFR WITH VSBYS ONE HALF MILE AND CIGS 002-003. AREAS FROM KMSP ON TO THE WEST..SNOW HAS GENERALLY ENDED WITH MVFR TO LOW END VFR CIGS IN PLACE. SNOW WINDING DOWN BY 06Z FROM KRNH TO KEAU WITH CIGS IMPROVING TO MVFR BUT POSSIBLE MVFR VSBYS IN SNOW. THERE IS A CHANCE FOR MVFR CIGS TO SCT OUT OVER MUCH OF THE MN TAF SITES BY MID MORNING SUNDAY...BUT A SECONDARY TROUGH WITH COLDER AIR COULD BRING BACK BKN VFR CIGS IN THE AFTERNOON...ESPECIALLY WEST CENTRAL MN. KMSP... LAST BAND OF SIG SNOW TO MOVE THROUGH THE AREA FOR THE NEXT HOUR TO HOUR AND A HALF AND THEN IMPROVING TO MVFR CIGS BUT OCNL IFR VSBYS TO 2SM. SNOW GENERALLY ENDING BY 05Z BUT MVFR CIG CONTINUING. CURRENTLY THINKING THAT LEVEL SHOULD REMAIN AT OR ABOVE 017Z. MAY BE ENOUGH DRYING FOR SCT LOW CLOUDS 025-040 BY SUNDAY AFTERNOON. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR ANOKA-BLUE EARTH-BROWN-CARVER-CHISAGO-DAKOTA-FARIBAULT-FREEBORN- GOODHUE-HENNEPIN-LE SUEUR-MARTIN-NICOLLET-RAMSEY-RICE-SCOTT- SIBLEY-STEELE-WASECA-WASHINGTON-WATONWAN. WI...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX. && $$ BAP/JPR
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
729 AM EST FRI DEC 2 2011 .SYNOPSIS... A QUICK-MOVING COLD FRONT WILL SWEEP THROUGH THE REGION TODAY WITH SCATTERED TO NUMEROUS SNOW SHOWERS AND POSSIBLE SNOW SQUALLS. THIS FRONT WILL BRING A POTENTIAL LIGHT SNOW ACCUMULATION ACROSS NORTHERN NEW YORK LATE THIS MORNING INTO EARLY THIS AFTERNOON...AND ACROSS NORTHERN VERMONT DURING THE EARLY TO MID AFTERNOON HOURS. SKIES CLEAR TONIGHT WITH HIGH PRESSURE BUILDING ACROSS THE NORTH COUNTRY. THIS WILL SET UP A CHILLY NIGHT WITH LOWS IN THE TEENS TO LOWER 20S. HIGH PRESSURE AND DRY WEATHER CONTINUE FOR THE WEEKEND WITH SEASONABLY COOL TEMPERATURES ON SATURDAY MODERATING TO ABOVE NORMAL BY SUNDAY ON GUSTY SOUTH WINDS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 312 AM EST FRIDAY...MID-LEVEL CLOUDS ARE GRADUALLY OVERSPREADING THE NORTH COUNTRY EARLY THIS MORNING IN ASSOCIATION WITH UPSTREAM TROUGH AND COLD FRONT ACROSS SERN ONTARIO INTO LOWER MICHIGAN. UPR TROUGH IS INITIALLY POSITIVE TILT...BUT BECOMES MORE NEUTRAL TODAY AND SWINGS RAPIDLY THRU THE NORTH COUNTRY AS A RATHER VIGOROUS WAVE THIS AFTN. NOT MUCH CHANGE FROM PREVIOUS FCST...WITH BEST THREAT FOR SNOW SHOWERS FROM 14-17Z IN THE SAINT LAWRENCE VALLEY...16-19Z IN THE ADIRONDACKS...17-21Z IN THE CHAMPLAIN VALLEY...AND 18-22Z ACROSS THE REST OF VERMONT. THE SNOW SHOWERS MAY BEGIN AS SOME LIGHT RAIN/SNOW IN THE VALLEY LOCATIONS WITH SURFACE TEMPERATURES CLOSE TO 40 DEGREES...BUT SHOULD CHANGE OVER TO SNOW AS THE PRECIPITATION CONTINUES TO FALL. NARROW AREAS OF 35-40 DBZ MODEL REFLECTIVITY INDICATED IN 3-KM HRRR AND 4-KM LOCAL WRF RUN ASSOCIATED WITH POSSIBLE SNOW SQUALL ACTIVITY. NOT MUCH SFC BASED INSTABILITY...BUT STEEP LAPSE RATES AND STRONG DEEP- LAYER VORTICITY ADVECTION COULD BE SUFFICIENT TO ORGANIZE BAND OF SNOW SQUALLS ACROSS NRN NY INTO NRN VT TODAY. GREATEST COVERAGE OF SNOW SHOWERS WILL LIKELY BE ACROSS NORTHERN NEW YORK AND INTO THE HIGHER ELEVATIONS OF NORTHERN VERMONT. ACCUMULATIONS WILL BE LIGHT...GENERALLY LESS THAN AN INCH...ALTHOUGH SOME OF THE HIGHER ELEVATIONS OF THE GREEN MOUNTAINS COULD SEE UP TO 2 INCHES. THIS MAY ACCUMULATE QUICKLY IN ANY SQUALLS...AND RESULT IN SLOW TRAVEL CONDITIONS FOR A BRIEF TIME WITH LOW VSBY. HAVE HIGHLIGHTED THREAT IN THE HAZARDOUS WEATHER OUTLOOK. HIGH TEMPERATURES WILL BE REACHED BEFORE THE ONSET OF PRECIPITATION...GENERALLY MID TO UPPER 30S...WITH SOME LOW 40S IN THE CHAMPLAIN VALLEY. TEMPERATURES WILL FALL QUICKLY WITH ONSET OF PCPN THROUGH THE 30S...AND INTO THE 20S AFTER THE PASSAGE OF THE FRONT. THERE COULD ALSO BE A PERIOD OF GUSTY NORTHWEST WINDS AFTER THE PASSAGE OF THE COLD FRONT LATE FRIDAY AFTERNOON AND EVENING WITH SOME GUSTS 15-30 MPH. CLEARING SKIES AND LIGHTER WINDS TONIGHT WITH STRONG SFC ANTICYCLONE CRESTING OVER THE NORTH COUNTRY AT 12Z SATURDAY. LOW TEMPERATURES GENERALLY IN THE TEENS...EXCEPT LOW 20S IN THE CHAMPLAIN VALLEY. COULD SEE AN ISOLD READING IN THE UPR SINGLE DIGITS IN THE NRN ADIRONDACKS...INCLUDING AT KSLK. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... AS OF 312 AM EST FRIDAY...RIDGE OF HIGH PRESSURE IN PLACE FOR SATURDAY...AND FEATURE WILL TRANSLATE SLOWLY EASTWARD TO THE GULF OF MAINE LATE IN THE DAY. THIS WILL ALLOW AIR MASS TO MODERATE WITH DEVELOPING SOUTH WINDS 5-10 MPH BY AFTN. LOOKING AT DRY WEATHER...MOSTLY SUNNY SKIES AND SEASONABLE HIGH TEMPS FOR EARLY DECEMBER IN THE MID-UPR 30S. SOUTH TO SOUTHWEST GRADIENT FLOW PICKS UP SATURDAY NIGHT AND ESPECIALLY ON SUNDAY. THESE WINDS AND PASSING MID-UPR CLOUDS WILL KEEP LOW TEMPERATURES A BIT MILDER FOR SATURDAY NIGHT...AND THEN TEMPS REBOUNDING INTO THE UPR 40S FOR SUNDAY. SOUTH WINDS COULD BE RATHER GUSTY SUNDAY...GENERALLY 15-25 MPH WITH GUSTS TO 35 MPH POSSIBLE PER 00Z NAM MODEL SOUNDINGS. A COLD FRONT WILL BE MOVING EWD THRU THE GREAT LAKES REGION LATE IN THE DAY. AT THIS TIME HELD OFF ON ANY PRECIPITATION ASSOCIATED WITH THIS FEATURE...THOUGH CLOUDS WILL BE ON THE INCREASE LATE SUNDAY. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 345 AM EST FRIDAY...LOW PRESSURE SITUATED TO OUR WEST ON SUNDAY EVENING WILL LIFT NORTH INTO CANADA OVERNIGHT...WEAK COLD FRONT ASSOCIATED WITH THIS LOW WILL CROSS OUR REGION THOUGH LIMITED MOISTURE ASSOCIATED WITH THIS FEATURE SO WILL ONLY MENTION CHANCE POPS AT THIS TIME. AFOREMENTIONED FRONT WILL STALL OUT TO SOUTHEAST AND SEVERAL WAVES OF MOISTURE WILL RIDE ALONG THIS FRONT BRINGING MORE PRECIPITATION TO THE REGION. THE GFS AND ECMWF BOTH SHOW THIS SCENARIO...BUT THE GFS SHOWS IT ENDING SOONER THAN THE ECMWF. THE ECMWF HANGS ONTO THE PRECIP ALL THE WAY THROUGH THURSDAY AND THE GFS ENDS THE PRECIP ON TUESDAY NIGHT. AT THIS TIME HAVE MENTIONED HIGHEST POPS FOR MONDAY NIGHT. TEMPERATURES WILL CONTINUE TO RUN WARMER THAN NORMAL THROUGH THE PERIOD. RIGHT NOW LOOKS LIKE THE MAJORITY OF THE PRECIP WE GET NEXT WEEK WILL BE RAIN WITH A POSSIBLE CHANGEOVER TO SNOW AT THE END OF THE EVENT. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... THROUGH 12Z SATURDAY...MAINLY VFR CONDITIONS EXPECTED THROUGH 15Z FRIDAY...AS A RIDGE OF HIGH PRESSURE SLOWLY MOVES EAST OF THE REGION...WITH SOME AREAS OF MVFR CEILINGS ACROSS NORTHERN NEW YORK. AN UPPER TROUGH WILL APPROACH THE REGION DURING THE DAY TODAY. EXPECTING AREAS OF IFR/MVFR IN LIGHT SNOW DEVELOPING ACROSS NORTHERN NEW YORK BETWEEN 16Z-18Z FRIDAY...AND THEN MOVING INTO VERMONT BETWEEN 19Z-21Z FRIDAY. WINDS WILL BE GUSTY WITH POSSIBLE SNOW SQUALLS DURING THIS TIME PERIOD ALSO. CONDITIONS WILL CLEAR UP BY ABOUT 00Z AND VFR RETURNS...CLEAR SKIES AND LIGHT WINDS ARE EXPECTED OVERNIGHT. . OUTLOOK 12Z SATURDAY THROUGH TUESDAY...MAINLY VFR CONDITIONS EXPECTED THROUGH THE PERIOD...AS A RIDGE OF HIGH PRESSURE WILL BE OVER THE REGION. SOME GUSTY SOUTHERLY WINDS ARE POSSIBLE ON SUNDAY DURING THE DAYTIME HOURS. AREAS OF MVFR/IFR CONDITIONS POSSIBLE IN RAIN AND SNOW SHOWERS MONDAY AND TUESDAY. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...BANACOS NEAR TERM...BANACOS SHORT TERM...BANACOS LONG TERM...NEILES AVIATION...NEILES
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
352 AM EST FRI DEC 2 2011 .SYNOPSIS... A QUICK-MOVING COLD FRONT WILL SWEEP THROUGH THE REGION TODAY WITH SCATTERED TO NUMEROUS SNOW SHOWERS AND POSSIBLE SNOW SQUALLS. THIS FRONT WILL BRING A POTENTIAL LIGHT SNOW ACCUMULATION ACROSS NORTHERN NEW YORK LATE THIS MORNING INTO EARLY THIS AFTERNOON...AND ACROSS NORTHERN VERMONT DURING THE EARLY TO MID AFTERNOON HOURS. SKIES CLEAR TONIGHT WITH HIGH PRESSURE BUILDING ACROSS THE NORTH COUNTRY. THIS WILL SET UP A CHILLY NIGHT WITH LOWS IN THE TEENS TO LOWER 20S. HIGH PRESSURE AND DRY WEATHER CONTINUE FOR THE WEEKEND WITH SEASONABLY COOL TEMPERATURES ON SATURDAY MODERATING TO ABOVE NORMAL BY SUNDAY ON GUSTY SOUTH WINDS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 312 AM EST FRIDAY...MID-LEVEL CLOUDS ARE GRADUALLY OVERSPREADING THE NORTH COUNTRY EARLY THIS MORNING IN ASSOCIATION WITH UPSTREAM TROUGH AND COLD FRONT ACROSS SERN ONTARIO INTO LOWER MICHIGAN. UPR TROUGH IS INITIALLY POSITIVE TILT...BUT BECOMES MORE NEUTRAL TODAY AND SWINGS RAPIDLY THRU THE NORTH COUNTRY AS A RATHER VIGOROUS WAVE THIS AFTN. NOT MUCH CHANGE FROM PREVIOUS FCST...WITH BEST THREAT FOR SNOW SHOWERS FROM 14-17Z IN THE SAINT LAWRENCE VALLEY...16-19Z IN THE ADIRONDACKS...17-21Z IN THE CHAMPLAIN VALLEY...AND 18-22Z ACROSS THE REST OF VERMONT. THE SNOW SHOWERS MAY BEGIN AS SOME LIGHT RAIN/SNOW IN THE VALLEY LOCATIONS WITH SURFACE TEMPERATURES CLOSE TO 40 DEGREES...BUT SHOULD CHANGE OVER TO SNOW AS THE PRECIPITATION CONTINUES TO FALL. NARROW AREAS OF 35-40 DBZ MODEL REFLECTIVITY INDICATED IN 3-KM HRRR AND 4-KM LOCAL WRF RUN ASSOCIATED WITH POSSIBLE SNOW SQUALL ACTIVITY. NOT MUCH SFC BASED INSTABILITY...BUT STEEP LAPSE RATES AND STRONG DEEP- LAYER VORTICITY ADVECTION COULD BE SUFFICIENT TO ORGANIZE BAND OF SNOW SQUALLS ACROSS NRN NY INTO NRN VT TODAY. GREATEST COVERAGE OF SNOW SHOWERS WILL LIKELY BE ACROSS NORTHERN NEW YORK AND INTO THE HIGHER ELEVATIONS OF NORTHERN VERMONT. ACCUMULATIONS WILL BE LIGHT...GENERALLY LESS THAN AN INCH...ALTHOUGH SOME OF THE HIGHER ELEVATIONS OF THE GREEN MOUNTAINS COULD SEE UP TO 2 INCHES. THIS MAY ACCUMULATE QUICKLY IN ANY SQUALLS...AND RESULT IN SLOW TRAVEL CONDITIONS FOR A BRIEF TIME WITH LOW VSBY. HAVE HIGHLIGHTED THREAT IN THE HAZARDOUS WEATHER OUTLOOK. HIGH TEMPERATURES WILL BE REACHED BEFORE THE ONSET OF PRECIPITATION...GENERALLY MID TO UPPER 30S...WITH SOME LOW 40S IN THE CHAMPLAIN VALLEY. TEMPERATURES WILL FALL QUICKLY WITH ONSET OF PCPN THROUGH THE 30S...AND INTO THE 20S AFTER THE PASSAGE OF THE FRONT. THERE COULD ALSO BE A PERIOD OF GUSTY NORTHWEST WINDS AFTER THE PASSAGE OF THE COLD FRONT LATE FRIDAY AFTERNOON AND EVENING WITH SOME GUSTS 15-30 MPH. CLEARING SKIES AND LIGHTER WINDS TONIGHT WITH STRONG SFC ANTICYCLONE CRESTING OVER THE NORTH COUNTRY AT 12Z SATURDAY. LOW TEMPERATURES GENERALLY IN THE TEENS...EXCEPT LOW 20S IN THE CHAMPLAIN VALLEY. COULD SEE AN ISOLD READING IN THE UPR SINGLE DIGITS IN THE NRN ADIRONDACKS...INCLUDING AT KSLK. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... AS OF 312 AM EST FRIDAY...RIDGE OF HIGH PRESSURE IN PLACE FOR SATURDAY...AND FEATURE WILL TRANSLATE SLOWLY EASTWARD TO THE GULF OF MAINE LATE IN THE DAY. THIS WILL ALLOW AIR MASS TO MODERATE WITH DEVELOPING SOUTH WINDS 5-10 MPH BY AFTN. LOOKING AT DRY WEATHER...MOSTLY SUNNY SKIES AND SEASONABLE HIGH TEMPS FOR EARLY DECEMBER IN THE MID-UPR 30S. SOUTH TO SOUTHWEST GRADIENT FLOW PICKS UP SATURDAY NIGHT AND ESPECIALLY ON SUNDAY. THESE WINDS AND PASSING MID-UPR CLOUDS WILL KEEP LOW TEMPERATURES A BIT MILDER FOR SATURDAY NIGHT...AND THEN TEMPS REBOUNDING INTO THE UPR 40S FOR SUNDAY. SOUTH WINDS COULD BE RATHER GUSTY SUNDAY...GENERALLY 15-25 MPH WITH GUSTS TO 35 MPH POSSIBLE PER 00Z NAM MODEL SOUNDINGS. A COLD FRONT WILL BE MOVING EWD THRU THE GREAT LAKES REGION LATE IN THE DAY. AT THIS TIME HELD OFF ON ANY PRECIPITATION ASSOCIATED WITH THIS FEATURE...THOUGH CLOUDS WILL BE ON THE INCREASE LATE SUNDAY. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 345 AM EST FRIDAY...LOW PRESSURE SITUATED TO OUR WEST ON SUNDAY EVENING WILL LIFT NORTH INTO CANADA OVERNIGHT...WEAK COLD FRONT ASSOCIATED WITH THIS LOW WILL CROSS OUR REGION THOUGH LIMITED MOISTURE ASSOCIATED WITH THIS FEATURE SO WILL ONLY MENTION CHANCE POPS AT THIS TIME. AFOREMENTIONED FRONT WILL STALL OUT TO SOUTHEAST AND SEVERAL WAVES OF MOISTURE WILL RIDE ALONG THIS FRONT BRINGING MORE PRECIPITATION TO THE REGION. THE GFS AND ECMWF BOTH SHOW THIS SCENARIO...BUT THE GFS SHOWS IT ENDING SOONER THAN THE ECMWF. THE ECMWF HANGS ONTO THE PRECIP ALL THE WAY THROUGH THURSDAY AND THE GFS ENDS THE PRECIP ON TUESDAY NIGHT. AT THIS TIME HAVE MENTIONED HIGHEST POPS FOR MONDAY NIGHT. TEMPERATURES WILL CONTINUE TO RUN WARMER THAN NORMAL THROUGH THE PERIOD. RIGHT NOW LOOKS LIKE THE MAJORITY OF THE PRECIP WE GET NEXT WEEK WILL BE RAIN WITH A POSSIBLE CHANGEOVER TO SNOW AT THE END OF THE EVENT. && .AVIATION /09Z FRIDAY THROUGH TUESDAY/... THROUGH 06Z SATURDAY...MAINLY VFR CONDITIONS EXPECTED THROUGH 15Z FRIDAY...AS A RIDGE OF HIGH PRESSURE SLOWLY MOVES EAST OF THE REGION...WITH SOME AREAS OF MVFR CEILINGS ACROSS NORTHERN NEW YORK. AN UPPER TROUGH WILL APPROACH THE REGION DURING THE DAY TODAY. EXPECTING AREAS OF IFR/MVFR IN LIGHT SNOW DEVELOPING ACROSS NORTHERN NEW YORK BETWEEN 16Z-18Z FRIDAY...AND THEN MOVING INTO VERMONT BETWEEN 19Z-21Z FRIDAY. CONDITIONS WILL CLEAR UP BY ABOUT 00Z AND VFR RETURNS. OUTLOOK 06Z SATURDAY THROUGH TUESDAY...MAINLY VFR CONDITIONS EXPECTED THROUGH THE PERIOD...AS A RIDGE OF HIGH PRESSURE WILL BE OVER THE REGION. SOME GUSTY SOUTHERLY WINDS ARE POSSIBLE ON SUNDAY DURING THE DAYTIME HOURS. AREAS OF MVFR/IFR CONDITIONS POSSIBLE IN RAIN AND SNOW SHOWERS MONDAY AND TUESDAY. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...BANACOS NEAR TERM...BANACOS SHORT TERM...BANACOS LONG TERM...NEILES AVIATION...NEILES
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
337 AM EST FRI DEC 2 2011 .SYNOPSIS... A QUICK-MOVING COLD FRONT WILL SWEEP THROUGH THE REGION TODAY WITH SCATTERED TO NUMEROUS SNOW SHOWERS AND POSSIBLE SNOW SQUALLS. THIS FRONT WILL BRING A POTENTIAL LIGHT SNOW ACCUMULATION ACROSS NORTHERN NEW YORK LATE THIS MORNING INTO EARLY THIS AFTERNOON...AND ACROSS NORTHERN VERMONT DURING THE EARLY TO MID AFTERNOON HOURS. SKIES CLEAR TONIGHT WITH HIGH PRESSURE BUILDING ACROSS THE NORTH COUNTRY. THIS WILL SET UP A CHILLY NIGHT WITH LOWS IN THE TEENS TO LOWER 20S. HIGH PRESSURE AND DRY WEATHER CONTINUE FOR THE WEEKEND WITH SEASONABLY COOL TEMPERATURES ON SATURDAY MODERATING TO ABOVE NORMAL BY SUNDAY ON GUSTY SOUTH WINDS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 312 AM EST FRIDAY...MID-LEVEL CLOUDS ARE GRADUALLY OVERSPREADING THE NORTH COUNTRY EARLY THIS MORNING IN ASSOCIATION WITH UPSTREAM TROUGH AND COLD FRONT ACROSS SERN ONTARIO INTO LOWER MICHIGAN. UPR TROUGH IS INITIALLY POSITIVE TILT...BUT BECOMES MORE NEUTRAL TODAY AND SWINGS RAPIDLY THRU THE NORTH COUNTRY AS A RATHER VIGOROUS WAVE THIS AFTN. NOT MUCH CHANGE FROM PREVIOUS FCST...WITH BEST THREAT FOR SNOW SHOWERS FROM 14-17Z IN THE SAINT LAWRENCE VALLEY...16-19Z IN THE ADIRONDACKS...17-21Z IN THE CHAMPLAIN VALLEY...AND 18-22Z ACROSS THE REST OF VERMONT. THE SNOW SHOWERS MAY BEGIN AS SOME LIGHT RAIN/SNOW IN THE VALLEY LOCATIONS WITH SURFACE TEMPERATURES CLOSE TO 40 DEGREES...BUT SHOULD CHANGE OVER TO SNOW AS THE PRECIPITATION CONTINUES TO FALL. NARROW AREAS OF 35-40 DBZ MODEL REFLECTIVITY INDICATED IN 3-KM HRRR AND 4-KM LOCAL WRF RUN ASSOCIATED WITH POSSIBLE SNOW SQUALL ACTIVITY. NOT MUCH SFC BASED INSTABILITY...BUT STEEP LAPSE RATES AND STRONG DEEP- LAYER VORTICITY ADVECTION COULD BE SUFFICIENT TO ORGANIZE BAND OF SNOW SQUALLS ACROSS NRN NY INTO NRN VT TODAY. GREATEST COVERAGE OF SNOW SHOWERS WILL LIKELY BE ACROSS NORTHERN NEW YORK AND INTO THE HIGHER ELEVATIONS OF NORTHERN VERMONT. ACCUMULATIONS WILL BE LIGHT...GENERALLY LESS THAN AN INCH...ALTHOUGH SOME OF THE HIGHER ELEVATIONS OF THE GREEN MOUNTAINS COULD SEE UP TO 2 INCHES. THIS MAY ACCUMULATE QUICKLY IN ANY SQUALLS...AND RESULT IN SLOW TRAVEL CONDITIONS FOR A BRIEF TIME WITH LOW VSBY. HAVE HIGHLIGHTED THREAT IN THE HAZARDOUS WEATHER OUTLOOK. HIGH TEMPERATURES WILL BE REACHED BEFORE THE ONSET OF PRECIPITATION...GENERALLY MID TO UPPER 30S...WITH SOME LOW 40S IN THE CHAMPLAIN VALLEY. TEMPERATURES WILL FALL QUICKLY WITH ONSET OF PCPN THROUGH THE 30S...AND INTO THE 20S AFTER THE PASSAGE OF THE FRONT. THERE COULD ALSO BE A PERIOD OF GUSTY NORTHWEST WINDS AFTER THE PASSAGE OF THE COLD FRONT LATE FRIDAY AFTERNOON AND EVENING WITH SOME GUSTS 15-30 MPH. CLEARING SKIES AND LIGHTER WINDS TONIGHT WITH STRONG SFC ANTICYCLONE CRESTING OVER THE NORTH COUNTRY AT 12Z SATURDAY. LOW TEMPERATURES GENERALLY IN THE TEENS...EXCEPT LOW 20S IN THE CHAMPLAIN VALLEY. COULD SEE AN ISOLD READING IN THE UPR SINGLE DIGITS IN THE NRN ADIRONDACKS...INCLUDING AT KSLK. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... AS OF 312 AM EST FRIDAY...RIDGE OF HIGH PRESSURE IN PLACE FOR SATURDAY...AND FEATURE WILL TRANSLATE SLOWLY EASTWARD TO THE GULF OF MAINE LATE IN THE DAY. THIS WILL ALLOW AIR MASS TO MODERATE WITH DEVELOPING SOUTH WINDS 5-10 MPH BY AFTN. LOOKING AT DRY WEATHER...MOSTLY SUNNY SKIES AND SEASONABLE HIGH TEMPS FOR EARLY DECEMBER IN THE MID-UPR 30S. SOUTH TO SOUTHWEST GRADIENT FLOW PICKS UP SATURDAY NIGHT AND ESPECIALLY ON SUNDAY. THESE WINDS AND PASSING MID-UPR CLOUDS WILL KEEP LOW TEMPERATURES A BIT MILDER FOR SATURDAY NIGHT...AND THEN TEMPS REBOUNDING INTO THE UPR 40S FOR SUNDAY. SOUTH WINDS COULD BE RATHER GUSTY SUNDAY...GENERALLY 15-25 MPH WITH GUSTS TO 35 MPH POSSIBLE PER 00Z NAM MODEL SOUNDINGS. A COLD FRONT WILL BE MOVING EWD THRU THE GREAT LAKES REGION LATE IN THE DAY. AT THIS TIME HELD OFF ON ANY PRECIPITATION ASSOCIATED WITH THIS FEATURE...THOUGH CLOUDS WILL BE ON THE INCREASE LATE SUNDAY. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 334 PM EST THURSDAY...AREA OF HIGH PRESSURE MOVES INTO THE GULF OF MAINE AND THE REGION GETS INTO SOUTHWESTERLY WARM ADVECTION REGIME. WARMING 850MB TEMPS AND INCREASING CLOUDS SUNDAY...WITH SLIGHT CHANCE SHOWERS TRENDING IN AREAL COVERAGE FROM WEST TO EAST LATER SUNDAY INTO SUNDAY NIGHT. HIGHS ON SUNDAY IN THE MID/UPPER 40S...THOUGH THESE COULD BE CLOSER TO 50 DEGREES IF FULL MIXING OCCURS. CLOUDY SKIES WILL LIMIT DEGREE OF NOCTURNAL COOLING SUNDAY NIGHT...WITH LOWS IN THE 30S. WHILE THE GFS AND ECWMF EXTENDED RANGE DATA SHOW A CLOUDY AND WET WEATHER PATTERN FOR THE EARLY TO MIDDLE PART OF NEXT WEEK...THERE STILL ARE DIFFERENCES ON SPECIFIC DETAILS. AN AREA OF LOW PRESSURE ON MONDAY WILL BRING CHANCE RAIN OR HIGHER TERRAIN SNOW SHOWERS TO THE NORTH COUNTRY. THE BAROCLINIC ZONE ASSOCIATED WITH THE STORM ON MONDAY LINGERS ACROSS THE REGION THROUGH TUESDAY AND WEDNESDAY WITH CONTINUED CHANCES FOR PRECIPITATION AS WAVES OF LOW PRESSURE MOVE NORTHEASTWARD ALONG IT. RECENT SOLUTIONS HAVE TRENDED WARMER THROUGH PARTS OR ALL OF THIS EVENT. HAVE KEPT CHANCE PRECIPITATION PROBABILITIES FOR RAIN OR SNOW SHOWERS GOING THOUGH MIDWEEK BEFORE TAPERING PRECIPITATION PROBABILITIES DOWN BY LATE WEEK. TEMPERATURES WILL CONTINUE TO RUN ABOVE AVERAGE THROUGH THE PERIOD. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... THROUGH 06Z SATURDAY...MAINLY VFR CONDITIONS EXPECTED THROUGH 15Z FRIDAY...AS A RIDGE OF HIGH PRESSURE SLOWLY MOVES EAST OF THE REGION...WITH SOME AREAS OF MVFR CEILINGS ACROSS NORTHERN NEW YORK. AN UPPER TROUGH WILL APPROACH THE REGION DURING THE DAY TODAY. EXPECTING AREAS OF IFR/MVFR IN LIGHT SNOW DEVELOPING ACROSS NORTHERN NEW YORK BETWEEN 16Z-18Z FRIDAY...AND THEN MOVING INTO VERMONT BETWEEN 19Z-21Z FRIDAY. CONDITIONS WILL CLEAR UP BY ABOUT 00Z AND VFR RETURNS. OUTLOOK 06Z SATURDAY THROUGH TUESDAY...MAINLY VFR CONDITIONS EXPECTED THROUGH THE PERIOD...AS A RIDGE OF HIGH PRESSURE WILL BE OVER THE REGION. SOME GUSTY SOUTHERLY WINDS ARE POSSIBLE ON SUNDAY DURING THE DAYTIME HOURS. AREAS OF MVFR/IFR CONDITIONS POSSIBLE IN RAIN AND SNOW SHOWERS MONDAY AND TUESDAY. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...BANACOS NEAR TERM...BANACOS SHORT TERM...BANACOS LONG TERM...LOCONTO AVIATION...NEILES
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
353 PM EST FRI DEC 2 2011 .SYNOPSIS... HIGH PRESSURE WILL BUILD INTO PENNSYLVANIA TONIGHT AND CONTROL THE LOCAL WEATHER UNTIL COLD FRONT MOVES IN FROM THE NORTHWEST EARLY NEXT WEEK. THE COLD FRONT WILL MOST LIKELY STALL OVER THE STATE AND LEAD TO RAIN FOR THE FIRST HALF OF THE WEEK. COLDER TEMPERATURES WITH SCATTERED SNOW SHOWERS WILL THEN ENSUE IN THE MID WEEK. && .NEAR TERM /UNTIL 10 PM THIS EVENING/... MID DECK ROLLING ACROSS THE AREA CURRENTLY WILL SLIDE TO THE EAST AND DISSIPATE SOME AS IT DOES SO. MOST LOCATIONS WILL STAY FAIR ALL EVENING. NEAR TERM GUID PORTRAYS THE LOW CLOUDS OVER THE NORTHWEST LASTING FOR ONLY A FEW HOURS THIS EVENING...WITH JUST A FLURRY OR TWO IN THE NW. HRRR PAINTS SOME FLURRIES IN THE SW/LAURELS...BUT WILL NOT MENTION AT THIS POINT. GUSTY WNW WINDS IN THE MTS WILL DIE DOWN QUICKLY THIS EVENING AS THE HIGH PRESSURE BUILDS IN FROM THE WEST. && .SHORT TERM /10 PM THIS EVENING THROUGH SATURDAY NIGHT/... CLEAR AND CALM FOR THE OVERNIGHT WITH AXIS OF SFC HIGH PRESSURE OVERHEAD BEFORE SUNRISE. SOME OF THE COLDEST TEMPERATURES SO FAR THIS YEAR. STILL LOOKING AT MINS AROUND 20F NEAR THE NEW YORK BORDER...BUT WOULD NOT BE SURPRISED TO SEE READINGS DROP INTO THE MID TEENS IN SOME OF THE NORMALLY COLDER SHELTERED VALLEY SPOTS. LLVL FLOW GOES S/SERLY DURING THE DAY SAT...AND TEMPS SHOULD RISE BACK TO NEAR NORMALS AFTER THE COLD START. CLOUDS WILL BE TOUGH TO FIND EARLY...BUT HIGH CLOUDS FROM WARM ADVECTION ALOFT WILL SHOW UP AS THE DAY CONTINUES. JUST P/C FOR SAT NIGHT WITH SFC HIGH STRETCHED OUT ALL ALONG THE EAST COAST. 8H TEMPS RISE TO +6C TO +8C BY SUN AM. DESPITE THIS...DECOUPLING WILL ALLOW THE MINS TO DIP TO THE M/U20S. && .LONG TERM /SUNDAY THROUGH FRIDAY/... MAINLY DRY CONDITIONS WILL PERSIST INTO SUNDAY. AN INCREASING SOUTHERLY BREEZE ON SUNDAY WILL HELP TO BOOST THE NEAR TO SLIGHTLY BELOW NORMAL MAX TEMPS SATURDAY...TO A GOOD 5-7F ABOVE NORMAL FOR SUNDAY. MAX TEMP DEPARTURES FROM NORMAL WILL BE GREATEST ACROSS THE WRN MTNS WHERE HIGHS IN THE U40S TO LOWER 50S WILL BE 10F OF MORE ABOVE NORMAL. PARTLY TO MOSTLY SUNNY SKIES WILL BE FOUND ACROSS THE ERN HALF OF THE STATE FOR MUCH OF SUNDAY...WHILE CLOUDS THICKEN UP ACROSS THE WEST THROUGHOUT THE DAY. THERE WILL BE A CHANCE FOR A FEW SHOWERS ACROSS THE FAR NW LATE. PUSHED BACK THE ARRIVAL TIME OF THE RAIN SHIELD THROUGH THE FORECAST AREA ON MONDAY AS LATEST GEFS HOLDS THE ANAMALOUS PWAT VALUES BACK INTO OHIO INTO MONDAY. THAT WILL OVERSPREAD THE AREA LATE MONDAY THROUGH TUESDAY AS THE FRONT CRAWLS ACROSS THE AREA. INTRODUCED RAIN MIXING WITH AND CHANGING TO SNOW SHOWERS AS THE COLD AIR MOVES IN TUESDAY NOGHT AND WEDNESDAY. THE TIMING OF THE COLDER AIR ARRIVAL WITH THE EXITING PRECIP SHIELD WILL LIMIT ANY APPRECIABLE ACCUMULATIONS. && .AVIATION /21Z FRIDAY THROUGH WEDNESDAY/... HIGH/MID CLOUD SHEET WILLDISSIPATE AS IT MOVES EAST THIS EVE...AND THE LOW/MVFR ALMOST-IFR DECK IN THE NW WILL ALSO BREAK UP EARLY TONIGHT. BY 03Z...IT SHOULD BE PRETTY MUCH CLEAR. THE CLEAR SKIES WILL LAST INTO THE DAYTIME SAT...WITH ONLY HIGH CLOUDS FOR SAT AFTN/NIGHT. GUSTY WINDS AT THIS TIME WILL DECREASE VERY RAPIDLY THIS EVENING AS THE HIGH PRESSURE OFF TO THE WEST SETS UP OVERHEAD. THE HIGH WILL SLOWLY MOVE TO THE EAST COAST THROUGH SATURDAY NIGHT. OUTLOOK... MON...RAIN/LOW CIGS POSSIBLE...MAINLY NW. TUE...RAIN/LOW CIGS POSSIBLE. WED...RAIN AREAWIDE TRANSITIONS TO SHSN NW. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO/DEVOIR NEAR TERM...DANGELO SHORT TERM...DANGELO LONG TERM...TYBURSKI AVIATION...DANGELO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1255 PM EST FRI DEC 2 2011 .SYNOPSIS... HIGH PRESSURE WILL BUILD INTO PENNSYLVANIA TONIGHT AND CONTROL THE LOCAL WEATHER UNTIL COLD FRONT MOVES IN FROM THE NORTHWEST EARLY NEXT WEEK. THE COLD FRONT WILL MOST LIKELY STALL OVER THE STATE AND LEAD TO RAIN FOR THE FIRST HALF OF THE WEEK. COLDER TEMPERATURES WITH SCATTERED SNOW SHOWERS WILL THEN ENSUE IN THE MID WEEK. && .NEAR TERM /UNTIL 10 PM THIS EVENING/... MID DECK ROLLING ACROSS THE AREA CURRENTLY WILL SLIDE TO THE EAST AND DISSIPATE SOME AS IT DOES SO. MOST LOCATIONS WILL STAY FAIR ALL EVENING. NEAR TERM GUID PORTRAYS THE LOW CLOUDS OVER THE NORTHWEST LASTING FOR ONLY A FEW HOURS THIS EVENING...WITH JUST A FLURRY OR TWO IN THE NW. HRRR PAINTS SOME FLURRIES IN THE SW/LAURELS...BUT WILL NOT MENTION AT THIS POINT. GUSTY WNW WINDS IN THE MTS WILL DIE DOWN QUICKLY THIS EVENING AS THE HIGH PRESSURE BUILDS IN FROM THE WEST. && .SHORT TERM /10 PM THIS EVENING THROUGH SATURDAY NIGHT/... CLEAR AND CALM FOR THE OVERNIGHT WITH AXIS OF SFC HIGH PRESSURE OVERHEAD BEFORE SUNRISE. SOME OF THE COLDEST TEMPERATURES SO FAR THIS YEAR. STILL LOOKING AT MINS AROUND 20F NEAR THE NEW YORK BORDER...BUT WOULD NOT BE SURPRISED TO SEE READINGS DROP INTO THE MID TEENS IN SOME OF THE NORMALLY COLDER SHELTERED VALLEY SPOTS. LLVL FLOW GOES S/SERLY DURING THE DAY SAT...AND TEMPS SHOULD RISE BACK TO NEAR NORMALS AFTER THE COLD START. CLOUDS WILL BE TOUGH TO FIND EARLY...BUT HIGH CLOUDS FROM WARM ADVECTION ALOFT WILL SHOW UP AS THE DAY CONTINUES. JUST P/C FOR SAT NIGHT WITH SFC HIGH STRETCHED OUT ALL ALONG THE EAST COAST. 8H TEMPS RISE TO +6C TO +8C BY SUN AM. DESPITE THIS...DECOUPLING WILL ALLOW THE MINS TO DIP TO THE M/U20S. && .LONG TERM /SUNDAY THROUGH FRIDAY/... MAINLY DRY CONDITIONS WILL PERSIST INTO SUNDAY. AN INCREASING SOUTHERLY BREEZE ON SUNDAY WILL HELP TO BOOST THE NEAR TO SLIGHTLY BELOW NORMAL MAX TEMPS SATURDAY...TO A GOOD 5-7F ABOVE NORMAL FOR SUNDAY. MAX TEMP DEPARTURES FROM NORMAL WILL BE GREATEST ACROSS THE WRN MTNS WHERE HIGHS IN THE U40S TO LOWER 50S WILL BE 10F OF MORE ABOVE NORMAL. PARTLY TO MOSTLY SUNNY SKIES WILL BE FOUND ACROSS THE ERN HALF OF THE STATE FOR MUCH OF SUNDAY...WHILE CLOUDS THICKEN UP ACROSS THE WEST THROUGHOUT THE DAY. THERE WILL BE A CHANCE FOR A FEW SHOWERS ACROSS THE NW LATE. AS THE UPPER FLOW BACKS...AND THE NRN AND SRN STREAM TROFS TO OUR WEST PHASE/AMPLIFY...THE CFRONT WILL SLOW SIGNIFICANTLY ACROSS THE REGION /AND MAY EVEN STALL OUT FOR A PERIOD MONDAY NIGHT THROUGH TUESDAY/. GFS AND EC BOTH INDICATE A PIECE OF THE SRN STREAM ENERGY HELPING TO FORM A QUASI-CLOSED UPPER LOW ACROSS THE OHIO VALLEY...THEN OPENING UP THE WAVE AS IT MOVES INTO THE NE U.S. DURING THE MIDWEEK. THE TIMING OF THIS FEATURE IS MUCH SLOWER ON THE EC...AND ALSO STRONGER...WHICH SUPPORTS A MORE WIDESPREAD AND MODERATELY HEAVY RAIN EVENT...MIXING WITH OR CHANGING TO SNOW ACROSS THE WRN MTNS WEDNESDAY THROUGH WED NIGHT. AGAIN THE GFS IS MORE PROGRESSIVE AND WEAKER...LEADING TO PRECIP IN THE FORM OF SHOWERS OR A FEW PERIODS OF STEADIER RAIN EXITING OUR ERN COUNTIES TUESDAY NIGHT. GEFS PLUMES...WITH A LARGE SPREAD IN TIMING/AMOUNT AND TYPE OF PRECIP...CAPTURE THIS HIGH UNCERTAINTY. THE CONFIDENCE THE EVENT OCCURRING IN ONE FORM OR ANOTHER IS HIGH THOUGH. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... HIGH/MID CLOUD SHEET WILLDISSIPATE AS IT MOVES EAST THIS EVE...AND THE LOW/MVFR ALMOST-IFR DECK IN THE NW WILL ALSO BREAK UP EARLY TONIGHT. BY 03Z...IT SHOULD BE PRETTY MUCH CLEAR. THE CLEAR SKIES WILL LAST INTO THE DAYTIME SAT...WITH ONLY HIGH CLOUDS FOR SAT AFTN/NIGHT. GUSTY WINDS AT THIS TIME WILL DECREASE VERY RAPIDLY THIS EVENING AS THE HIGH PRESSURE OFF TO THE WEST SETS UP OVERHEAD. THE HIGH WILL SLOWLY MOVE TO THE EAST COAST THROUGH SATURDAY NIGHT. OUTLOOK... MON...RAIN/LOW CIGS POSSIBLE...MAINLY NW. TUE...RAIN/LOW CIGS POSSIBLE. WED...RAIN AREAWIDE TRANSITIONS TO SHSN NW. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO/DEVOIR NEAR TERM...DANGELO SHORT TERM...DANGELO LONG TERM...LAMBERT/CERU AVIATION...DANGELO
AREA FORECAST DISCUSSION
NWS AUSTIN/SAN ANTONIO TX
933 PM CST SAT DEC 3 2011 .UPDATE... PRE-FRONTAL TROUGH EXTENDS FROM WACO TO LAMPASAS TO JUNCTION TO DRYDEN WHILE CANADIAN COLD FRONT EXTENDS FROM WICHITA FALLS TO ABILENE TO MIDLAND. TROUGH AND FRONT HAVE SPEED UP SLIGHTLY AND NEW 00Z NAM AND RUC BRING THESE FEATURES THROUGH SOUTH CENTRAL TEXAS A LITTLE EARLIER THAN PREVIOUSLY FORECAST WHICH SEEMS REASONABLE. MAIN IMPACTS ARE TO GO WITH COOLER TEMPERATURES AND EARLIER WIND SHIFTS TO NORTHERLY ON SUNDAY...ESPECIALLY DURING THE LATE MORNING AND AFTERNOON ALONG WITH LOWER POST-FRONTAL DEWPOINTS FOR SUNDAY THROUGH MONDAY. REMAINDER OF YOUR SOUTH CENTRAL TEXAS FORECAST IS ON TRACK. && .PREV DISCUSSION... /ISSUED 538 PM CST SAT DEC 3 2011/ AVIATION... A BRIEF WINDOW OF VFR CONDITIONS WILL CONTINUE THROUGH THE NEXT FEW HOURS BEFORE THE ONSET OF MVFR CIGS BY ABOUT 03Z. STREAMER SHOWERS WILL CONTINUE TO DEVELOP MAINLY EAST OF A LINE FROM KERV TO KHDO TO KCOT THROUGH THE EVENING HOURS AS WARM AIR ADVECTION PERSISTS IN ADVANCE OF AN APPROACHING COLD FRONT. THE DEEP MOISTURE IN THE LOWER LEVELS WILL PROMOTE THE DETERIORATION OF CIGS TO IFR AND POTENTIALLY LIFR CONDITIONS OVERNIGHT. AHEAD OF THE FRONT...A MIX OF -DZ/BR/-SHRA IS EXPECTED TO LOWER VSBYS TO MVFR/IFR PARTICULARLY AT KAUS/KSAT/KSSF. THE COLD FRONT WILL ARRIVE SUNDAY MORNING...BUT IMPROVEMENTS TO CIGS AND VSBYS WILL BE SLOW WITH VFR CONDITIONS NOT EXPECTED TO RETURN DURING THE 24-HR NOR 30-HR TAF PERIODS. PREV DISCUSSION... /ISSUED 314 PM CST SAT DEC 3 2011/ DISCUSSION... PRE-FRONTAL TROUGH/DRY LINE HAS PUSHED INTO THE FAR WESTERN CWA THIS AFTERNOON WITH GOOD MIXING/CLEARING ACROSS THE WESTERN COUNTIES. THE SKIES OVER THE EASTERN COUNTIES GENERALLY ALONG AND EAST OF I35 HAVE REMAINED MOSTLY CLOUDY WITH PATCHY LIGHT RAIN AND DRIZZLE CONTINUING IN THE DEEP SLY GULF FLOW. RAIN CHANCES WILL INCREASE AGAIN LATER THIS EVENING INTO THE OVERNIGHT HOURS AND SUNDAY. COMBINATION OF UPPER AIR DISTURBANCES IN THE SWLY FLOW ALOFT...CONVERGENCE ALONG THE PRE-FRONTAL SURFACE TROF...AND THE INCREASING LOW LEVEL GULF FLOW WILL RESULT IN GOOD CHANCES FOR DEEP CONVECTION. BECAUSE OF THE DEEP GULF INFLOW AHEAD OF THE TROUGH...WILL SEE GENEROUS QPF VALUES ESPECIALLY ACROSS THE NE/ERN COUNTIES. RAINFALL AMOUNTS OF ONE HALF TO ONE INCH OVER THE NEXT 24 HOURS WITH ISOLATED STORM TOTALS OF NEAR 2 INCHES POSSIBLE. THE COLD FRONT WAS PUSHING THROUGH THE TX PANHANDLE THIS AFTERNOON AND MODELS HAVE SLOWED THE PROGRESSION THRU S TX ON DURING THE DAY ON SUNDAY. CURRENT THINKING IS A FRONTAL PASSAGE INTO THE NRN HILL COUNTRY/EDWARDS PLATEAU BY 6 AM AND TO NEAR I10/HIGHWAY 90 BY AROUND NOON...AND THRU THE REMAINDER OF THE CWA BY 5 PM. HIGH TEMPERATURES WILL OCCUR JUST AHEAD OF THE COLD FRONT AND TEMPS ACROSS THE SRN CWA COULD REACH THE MID OR UPPER 70S. WILL SEE SLOWLY FALLING TEMPERATURES BEHIND THE FRONT AS COLD AIR ADVECTION WILL BEHIND TO INCREASE LATE SUNDAY NIGHT INTO MONDAY. MONDAY WILL BE THE MORE BONE CHILLING DAY WITH THE COMBINATION OF COLD...WIND AND POST FRONTAL OVERRUNNING LIGHT RAIN. WINTER PRECIPITATION FOR THE FAR NRN COUNTIES APPEARS UNLIKELY GIVEN THE WARMER 12Z SOUNDING TEMP PROFILE FOR MONDAY NIGHT/TUESDAY MORNING...AND MOST PRECIPITATION WILL BE ENDING FROM THE WEST BY SUNRISE TUESDAY MORNING. GRADUAL CLEARING TUESDAY WITH ALLOW FOR A COUPLE OF NIGHTS OF FREEZING TEMPERATURES AREA WIDE TUESDAY NIGHT AND WEDNESDAY NIGHT. STRONG WESTERLY FLOW ALOFT WILL RESULT IN A QUICK RETURN OF MOISTURE AND OVERRUNNING SETTING UP FOR LATE THURSDAY INTO FRIDAY AHEAD OF THE NEXT COLD FRONT. ANOTHER FAIRLY GOOD SHOT OF COLD CANADIAN AIR WILL ARRIVE FRIDAY NIGHT INTO SATURDAY...HOWEVER IT DOES NOT APPEAR THERE WILL BE ANY POST FRONTAL PRECIPITATION AS A DRY WNWLY FLOW DEVELOP BEHIND A SHORT WAVE AS THE COLD AIR ADVECTION BEGINS. && .PRELIMINARY POINT TEMPS/POPS... AUSTIN CAMP MABRY 54 58 44 49 36 / 80 80 90 60 20 AUSTIN BERGSTROM INTL AIRPORT 57 59 43 50 34 / 80 80 90 60 30 NEW BRAUNFELS MUNI AIRPORT 62 63 44 50 35 / 70 70 80 50 20 BURNET MUNI AIRPORT 47 49 40 47 35 / 80 80 90 50 20 DEL RIO INTL AIRPORT 55 56 45 52 36 / 50 30 50 20 10 GEORGETOWN MUNI AIRPORT 52 55 40 47 34 / 80 80 90 60 20 HONDO MUNI AIRPORT 63 63 45 53 35 / 70 50 80 30 20 SAN MARCOS MUNI AIRPORT 61 63 45 48 36 / 70 70 90 50 30 LA GRANGE - FAYETTE REGIONAL 64 67 48 50 38 / 70 80 90 70 30 SAN ANTONIO INTL AIRPORT 62 63 46 53 37 / 70 60 80 40 20 STINSON MUNI AIRPORT 64 64 47 52 38 / 70 60 80 40 20 && .EWX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ MESOSCALE/AVIATION...25 SYNOPTIC/GRIDS...04 PUBLIC SERVICE/DATA COLLECTION...19
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
613 PM CST SAT DEC 3 2011 .UPDATE... PRECIP CONTINUES TO EXPAND IN AREAL COVERAGE OVER THE NORTHEAST QUADRANT OF THE CWA. LATEST RUC ANALYSIS SHOWS THE STRONG LIFT RESPONSIBLE FOR THE PRECIP ON THE 295K ISENTROPIC SURFACE. 35 KNOT SOUTHERLY WINDS ARE QUICKLY LIFTING MOIST PARCELS FROM 975 MB TO 875 MB AS THE COLDER AIR MASS MOVES EAST. UPPED POPS IN THE 0-6Z TIMEFRAME TO 100 PERCENT FOR AREAS EAST AND NORTH OF A SHERMAN TO DALLAS TO CANTON LINE GIVEN THE EXPECTED INTENSITY OF THIS LIFT AND CURRENT RADAR TRENDS. THE RUC SHIFTS THE BEST LIFT ASSOCIATED WITH THE COLD AIR WEDGE TO THE SOUTH LATER TONIGHT AND WILL HAVE 80 POPS FOR THE SOUTHERN ZONES AFTER 6Z. WIDESPREAD PRECIP IS EXPECTED TOMORROW BEHIND THE FRONTAL BOUNDARY AS WARM/MOIST AIR IS LIFTED OVER THE COLD AIR. BUMPED UP POPS TO 100 PERCENT FOR MOST OF THE CWA EXCEPT FOR THE NORTHWESTERN ZONES FOR THE SUNDAY PERIOD. 85/NH && .AVIATION... BAND OF RAIN WILL CONTINUE TO MOVE THROUGH THE DFW TRACON DURING THE NEXT FEW HOURS...BUT WILL SLOWLY CLEAR FROM WEST TO EAST. HAVE INCLUDED VCTS AT DAL DUE TO PROXIMITY TO STRONGER CELL...BUT ANY STORMS WILL BE VERY ISOLATED. DRIER AIR IS MOVING IN FROM THE WEST AND CIGS WILL START OFF AT MVFR BUT SHOULD IMPROVE TO VFR WHEN RAIN ENDS. HAVE RAIN ENDING AT 1Z AT FTW/AFW...2Z DFW/GKY...3Z AT DAL. VFR WITH NO RAIN SHOULD PREVAIL FROM LATE THIS EVENING...BUT MORE RAIN DEVELOP LATE TONIGHT AROUND 9Z FROM THE SOUTH. THIS RAIN WILL BE FALLING FROM THE MID LEVELS AND THUS CONDITIONS MAY STAY VFR UNTIL LOW LEVELS CAN SATURATE TOWARD SUNRISE. EXPECT RAIN/BR TO CONTRIBUTE TO MVFR VSBY...WITH CIGS LIKELY FALLING TO IFR BY LATE MORNING. RAIN SHOULD PREVAIL THROUGH THE DAY TOMORROW AND THINK CIGS STAY IFR IN DAMP/CHILLY AIR MASS. FOR WACO...BAND OF RAIN SHOULD MOVE IN AROUND 2-3Z AND DO NOT EXPECT THE PUSH OF DRY AIR TO MAKE IT IN THERE THIS EVENING BEFORE NEXT BATCH OF RAIN DEVELOPS FROM THE SOUTH. WILL PREVAIL RAIN WITH MVFR CIGS THIS EVENING...WITH CIGS FALLING TO IFR DURING THE OVERNIGHT AND STAYING THERE INTO TOMORROW AS WELL. WINTER PRECIP POTENTIAL STILL LOOKS LOW IN DFW AREA...WITH SURFACE TEMPERATURES LIKELY REMAINING ABOVE FREEZING WHEN PRECIP IS FALLING. MODELS ARE UNANIMOUS ON FORECASTING TEMPS ABOVE FREEZING AND AM NOT IMPRESSED WITH AMOUNT OF COLD AIR AVAILABLE ACROSS THE NORTHERN AND CANADIAN PLAINS. DYNAMIC COOLING ALOFT MAY BRING RAIN/SNOW LINE INTO CWA...BUT THIS STILL LOOKS LIKE IT WILL STAY NW OF METROPLEX TAF SITES. TR.92 && .PREV DISCUSSION... /ISSUED 321 PM CST SAT DEC 3 2011/ SHORTWAVE DISTURBANCE CONTINUES TO LIFT UP THROUGH THE SOUTHERN PLAINS THIS AFTERNOON RESULTING IN THE SLOW EASTWARD PROGRESSION OF A BAND OF LIGHT TO MODERATE RAIN CURRENTLY ALONG A LINE FROM COMANCHE TO WEATHERFORD TO GAINESVILLE. LOW RAINFALL AMOUNTS FOR MOST AREAS...BUT SOME ISOLATED AMOUNTS TO BETWEEN A QUARTER AND HALF INCH WILL BE POSSIBLE AS THIS BAND MOVES ACROSS NORTH TEXAS. THE RAIN-COOLED AIR HAS RESULTED IN THE OLD FRONT SAGGING TO A GAINESVILLE TO DECATUR TO CISCO LINE THIS AFTERNOON WITH TEMPERATURES IN THE 50S BEHIND THE FRONT WHILE REMAINING IN THE 60S TO LOWER 70S AHEAD OF IT. A FEW EMBEDDED THUNDERSTORMS ARE POSSIBLE...BUT NOT LIKELY THROUGH THIS EVENING. A STRONGER COLD FRONT CAN BE SEEN NOW MOVING THROUGH THE HIGH PLAINS OF EASTERN CO/WESTERN KS THIS AFTERNOON. THE FRONT SHOULD ARRIVE INTO OUR FAR NORTHWEST COUNTIES BY MIDNIGHT...THEN QUICKLY PUSH TO AN ATHENS...WACO...LAMPASAS LINE BY SUNRISE SUNDAY. THE FRONT WILL CLEAR THE REMAINDER OF NORTH TEXAS BY LATE MORNING SUNDAY. THE STRONG COLD FRONT WILL OVERTAKE OUR CURRENT FRONT WITH THE BULK OF MODERATE RAIN AND ISOLATED THUNDERSTORMS OCCURRING AHEAD OF THE FRONT. SOME LIGHT RAIN WILL LIKELY REMAIN BEHIND THE FRONT. HIGHS SUNDAY WILL OCCUR BETWEEN MIDNIGHT AND MIDDAY SUNDAY...WITH FALLING AFTERNOON TEMPERATURES AND GUSTY NORTH WINDS 15 TO 20 MPH AFTER FROPA. THE GUSTY WINDS AND LIGHT RAIN WILL MAKE FOR A RAW AND WET DAY ACROSS NORTH TEXAS...THOUGH OVERALL HEAVIER RAINFALL SHOULD SHIFT TO THE SOUTH AND EAST OF OUR AREA LATE SUNDAY AFTERNOON AND EVENING. A MORE ROBUST SHORTWAVE DISTURBANCE ARRIVES LATE SUNDAY NIGHT INTO MONDAY AND WILL INDUCE ISENTROPIC ASCENT ONCE AGAIN WITH A COLD AND AT TIMES MODERATE RAIN ACROSS NORTH TEXAS. TEMPERATURES WILL LIKELY FALL INTO THE MID 30S BY DAYBREAK MONDAY MORNING ACROSS AREAS TO THE NORTHWEST OF THE DFW METROPLEX. MOST MODELS...INCLUDING SREF AND WRF ...ARE HOLDING THE DEEPER COLD AIR OFF TO THE NORTHWEST OF THIS AREA THROUGH MIDDAY MONDAY. DESPITE TEMPERATURES JUST ABOVE FREEZING...A RAIN/SNOW MIX COULD OCCUR ACROSS THIS AREA MONDAY MORNING AS THERMAL PROFILES COOL QUICKLY TO OR JUST BELOW FREEZING. COLD RAIN IS EXPECTED ELSEWHERE. REGARDING THE WINTER WEATHER POTENTIAL...AS THE SHORTWAVE MOVES QUICKLY ACROSS THE AREA...DRYING ABOVE THE BOUNDARY LAYER WILL FOLLOW IN ITS WAKE. AS A RESULT OF THIS DRYING...ICE CRYSTAL PRODUCTION WILL BE LIMITED AND A MIXTURE OF VERY LIGHT RAIN/ DRIZZLE/FLURRIES IS LIKELY. ISENTROPIC DOWNSLOPE CONTINUES DURING THE OVERNIGHT HOURS INTO TUESDAY MORNING WITH CLOUDS GRADUALLY DECREASING. NORTH TEXAS WILL REMAIN UNDER THE INFLUENCE OF CYCLONIC FLOW ALOFT THROUGH THE WEEK...RESULTING IN PARTLY CLOUDY SKIES AND COLD CONDITIONS. THE STUBBORN UPPER LOW FINALLY OPENS UP AND LIFTS OUT TUES NIGHT AND EARLY WEDNESDAY WITH SOME LIFT RETURNING TO THE NORTH TEXAS. AT THIS TIME...WE FEEL MOISTURE WILL BE TOO LIMITED FOR PRECIPITATION BUT WILL MONITOR CLOSELY. WE CONTINUE TO UNDERCUT MOS HIGH TEMPERATURES SINCE THE COLD AIRMASS IS 5-7 KFT DEEP WITH ONLY A SLOW MODIFICATION BY THURSDAY. NEXT COLD FRONT IS EXPECTED TO ARRIVE FRIDAY...AS ANOTHER SHORTWAVE DISTURBANCE MOVES SOUTHEAST ACROSS THE FRONT RANGE OF THE ROCKIES. GFS IS THE FASTEST WITH THE COLD FRONT...WHILE THE SREF/CANADIAN/AND ARE ECMWF SLOWER. FOR NOW...WILL LEAN TOWARD A SLOW CONSENSUS ON THE FRONT WITH WARMER TEMPERATURES FRIDAY THAN WHAT THE MAV MOS GUIDANCE. WE WILL ALSO LEAVE THIS PERIOD DRY WITH UNCERTAINTIES ON MOISTURE AVAILABILITY AND TIMING OF BOTH SURFACE AND UPPER LEVEL FEATURES. 05/42 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 41 45 38 40 29 / 80 100 90 60 20 WACO, TX 48 49 39 44 30 / 70 100 90 60 20 PARIS, TX 49 50 38 44 29 / 100 100 80 70 20 DENTON, TX 38 42 37 38 27 / 70 100 80 60 20 MCKINNEY, TX 42 45 37 41 29 / 100 100 80 60 20 DALLAS, TX 43 47 38 41 30 / 90 100 90 60 20 TERRELL, TX 49 49 39 44 30 / 100 100 90 70 20 CORSICANA, TX 52 52 40 45 31 / 70 100 90 70 20 TEMPLE, TX 54 54 40 46 30 / 80 100 90 60 20 MINERAL WELLS, TX 37 41 34 36 26 / 40 90 70 60 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 85/85
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
545 AM CST FRI DEC 2 2011 .UPDATE... SEE AVIATION DISCUSSION BELOW. && .AVIATION... AVIATION CONDITIONS WILL REMAIN PROBLEMATIC THROUGH THE PERIOD ACROSS WEST CENTRAL TEXAS TERMINALS. COLD FRONT HAS CLEARED ALL OF THE SITES EARLY THIS MORNING...WITH MVFR CIGS AND PATCHY AREAS OF LIGHT RAIN BEHIND THE FRONT. THESE CONDITIONS SHOULD PERSIST FOR MUCH OF THE MORNING HOURS...AND PROBABLY WELL INTO THE AFTERNOON. AS A STRONG LOW LEVEL JET BRINGS MOISTURE UP AND OVER THE BOUNDARY LATE THIS AFTERNOON AND INTO TONIGHT...CONDITIONS SHOULD QUICKLY DETERIORATE ACROSS ALL SITES...PERHAPS EVEN DOWN INTO THE LIFR RANGE. HOW QUICKLY THIS HAPPENS...AND WHEN IT STARTS REMAINS A BIG QUESTION THOUGH. WITH THIS MUCH WARM ADVECTION OVER THE FRONT...THE FRONT WILL EVENTUALLY BEGIN TO LIFT BACK NORTH AS A WARM FRONT. AGAIN...WHEN THIS STARTS TO OCCUR IS VERY UNCERTAIN...BUT ANTICIPATING A RAPID NORTHWARD MOVEMENT OF THE FRONT BACK TO NEAR THE INTERSTATE 20 CORRIDOR BY MORNING. CONDITIONS NORTH OF THE FRONT WILL CONTINUE TO BE A CONCERN..BUT CONDITIONS SOUTH OF THE FRONT MAY ACTUALLY IMPROVE BY SUNRISE SATURDAY MORNING. && .PREV DISCUSSION... /ISSUED 345 AM CST FRI DEC 2 2011/ SHORT TERM... COMPLICATED FORECAST CONTINUES FOR WEST CENTRAL TEXAS. STRONG COLD FRONT HAS CLEARED ALL BUT THE EXTREME SOUTHEAST PORTIONS OF THE AREA AS OF 09Z...WITH ONLY JUNCTION AND MASON HAVING NOT SEEN THE FRONTAL PASSAGE SO FAR. THE NAM AND THE RUC HAVE BOTH HANDLED THE MOVEMENT OF THE FRONT IN THE SHORT TERM FAIRLY WELL...AND THEY BOTH PUSH THE FRONT THROUGH THE REMAINDER OF THE AREA BY 12Z...AND THEN STALL IT JUST TO THE SOUTH. PRESSURE RISES BEHIND THE FRONT HAVE SLOWLY DECREASED...BUT THE GUSTY NORTH WINDS CONTINUE. GIVEN THESE WINDS...AND THE DENSITY OF THE COLDER AIR MASS...WILL ASSUME THAT THE MODELS ARE CORRECT IN PUSHING THE FRONT THROUGH THE REST OF THE AREA BEFORE PULLING UP STATIONARY. MEANWHILE...POTENT UPPER LEVEL STORM SYSTEM APPROACHING FROM THE SOUTHWEST US WILL LEAD TO INCREASING WARM ADVECTION UP AND OVER THE FRONTAL BOUNDARY...REACHING 40 KTS BY 00Z AND OVER 50 KTS BY MIDNIGHT. DRIZZLE AND LIGHT RAIN HAS ALREADY BEEN DEVELOPING...AND THIS WILL CONTINUE AS THIS ISENTROPIC LIFT STRENGTHENS. HAVE INCREASED POPS FOR TODAY AND TONIGHT. THIS WARM AND MOIST AIR MASS WILL RIDE UP AND OVER THE COLDER AIR AT THE SURFACE...LEAVING THE BOUNDARY TO THE SOUTH. HOWEVER...AS THE WARM ADVECTION INTENSIFIES...THE FRONTAL BOUNDARY WILL BEGIN TO LIFT NORTHWARD THIS EVENING...ALTHOUGH HOW FAR NORTH IS STILL A BIG QUESTION. IN ANY CASE...DONT EXPECT TEMPERATURES TO DROP MUCH TONIGHT...AND ACROSS MOST OF THE AREA..TEMPERATURES WILL ACTUALLY CLIMB SUBSTANTIALLY OVERNIGHT. 07 LONG TERM... A COLD AND UNSETTLED PATTERN WILL CONTINUE THROUGH MUCH OF THE EXTENDED FORECAST. A MODEST WARM UP CAN BE EXPECTED ON SATURDAY AS WARM FRONT LIFTS NORTH THROUGH WEST CENTRAL TEXAS. HIGH TEMPERATURES WILL RANGE FROM NEAR 60 NORTH...TO NEAR 70 SOUTH. IN THE MEANTIME...A LARGE UPPER LEVEL TROUGH WILL BE LOCATED ACROSS THE DESERT SOUTHWEST...AND AN ARCTIC COLD FRONT WILL BE LOCATED OVER THE SOUTHERN PLAINS. AN UPPER LEVEL SHORTWAVE TROUGH WILL TRACK ACROSS THE NORTHERN PLAINS SATURDAY HELPING TO SEND THIS COLD FRONT THROUGH WEST CENTRAL TEXAS SATURDAY NIGHT. SHOWERS WILL BE POSSIBLE ALONG AND AHEAD OF THE BOUNDARY...AND THIS IS REFLECTED IN THE CURRENT GRIDS. COLD AIR ADVECTION...CLOUD COVER AND LIGHT RAIN WILL HELP TO KEEP TEMPERATURES DOWN ON SUNDAY. DROPPED HIGH TEMPERATURES A FEW DEGREES...GENERALLY IN THE UPPER 30S TO MID 40S...AND THESE MAY NEED TO BE LOWERED ON FUTURE SHIFTS. ON SUNDAY NIGHT...AFOREMENTIONED UPPER LEVEL TROUGH REMAINS ACROSS THE DESERT SOUTHWEST...WHILE ANOTHER UPPER LEVEL SHORTWAVE TROUGH SKIRTS ACROSS THE CENTRAL PLAINS. THIS WILL HELP TO SEND A REINFORCING SHOT OF COLDER AIR INTO THE AREA...WITH NORTH WINDS INCREASING MONDAY MORNING AND COLD AIR FILTERING IN. IN ADDITION...UPPER LEVEL DISTURBANCES WILL CONTINUE TO MOVE ACROSS THE AREA IN ADVANCE OF THE MAIN UPPER LEVEL TROUGH LOCATED OVER THE SOUTHWEST STATES. THIS WILL LIKELY PRODUCE LIGHT PRECIPITATION ACROSS THE AREA SUNDAY NIGHT AND MONDAY. THE MAIN QUESTION THEN BECOMES...WHAT TYPE OF PRECIPITATION. MODEL SOUNDINGS AND 700MB/850MB TEMPERATURES ARE INDICATING A RAIN/SNOW MIX ACROSS THE NORTHERN HALF OF THE AREA EARLY MONDAY...THEN TRANSITIONING TO RAIN/SNOW ACROSS MUCH OF THE AREA BY LATE MONDAY...AND MOSTLY SNOW ACROSS THE NORTHERN COUNTIES. THIS SCENARIO IS REFLECTED IN THE CURRENT FORECAST PACKAGE. AT THIS TIME ANY ACCUMULATIONS SHOULD BE LIGHT...BUT A LOT OF UNCERTAINTY REMAINS IN THE AMOUNT OF PRECIPITATION AND THE PRECIPITATION TYPE SUNDAY AND MONDAY. HIGH TEMPERATURES ON MONDAY WILL BE WELL BELOW NORMAL...RANGING FROM THE MID 30S NORTH...TO NEAR 40 SOUTH. GIVEN THE FRIGID AIRMASS AND EXPECTED CLOUD COVER...THE CURRENT HIGH TEMPERATURES IN THE FORECAST MAY BE A BIT HIGH. MODELS CONTINUE TO HANG THE UPPER LEVEL TROUGH WEST OF THE AREA...BEFORE FINALLY SWINGING IT THROUGH LATE TUESDAY. INTRODUCED SLIGHT CHANCE POPS ACROSS THE AREA MONDAY NIGHT...BEFORE CONDITIONS IMPROVE TUESDAY MORNING. ANY PRECIPITATION THAT DOES OCCUR WILL LIKELY FALL AS LIGHT SNOW. ANOTHER VERY COLD DAY IS LIKELY ON TUESDAY...AND DROPPED TEMPERATURES A FEW DEGREES. A SLOW WARM UP WILL ENSUE BY THE MIDDLE OF NEXT WEEK...WITH CLOSER TO NORMAL TEMPERATURES RETURNING BY THURSDAY. DANIELS && .PRELIMINARY POINT TEMPS/POPS... ABILENE 38 38 63 32 39 / 60 60 60 20 30 SAN ANGELO 44 44 66 35 42 / 50 60 50 20 20 JUNCTION 55 55 69 40 44 / 40 60 40 50 40 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 07
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
345 AM CST FRI DEC 2 2011 .SHORT TERM... COMPLICATED FORECAST CONTINUES FOR WEST CENTRAL TEXAS. STRONG COLD FRONT HAS CLEARED ALL BUT THE EXTREME SOUTHEAST PORTIONS OF THE AREA AS OF 09Z...WITH ONLY JUNCTION AND MASON HAVING NOT SEEN THE FRONTAL PASSAGE SO FAR. THE NAM AND THE RUC HAVE BOTH HANDLED THE MOVEMENT OF THE FRONT IN THE SHORT TERM FAIRLY WELL...AND THEY BOTH PUSH THE FRONT THROUGH THE REMAINDER OF THE AREA BY 12Z...AND THEN STALL IT JUST TO THE SOUTH. PRESSURE RISES BEHIND THE FRONT HAVE SLOWLY DECREASED...BUT THE GUSTY NORTH WINDS CONTINUE. GIVEN THESE WINDS...AND THE DENSITY OF THE COLDER AIR MASS...WILL ASSUME THAT THE MODELS ARE CORRECT IN PUSHING THE FRONT THROUGH THE REST OF THE AREA BEFORE PULLING UP STATIONARY. MEANWHILE...POTENT UPPER LEVEL STORM SYSTEM APPROACHING FROM THE SOUTHWEST US WILL LEAD TO INCREASING WARM ADVECTION UP AND OVER THE FRONTAL BOUNDARY...REACHING 40 KTS BY 00Z AND OVER 50 KTS BY MIDNIGHT. DRIZZLE AND LIGHT RAIN HAS ALREADY BEEN DEVELOPING...AND THIS WILL CONTINUE AS THIS ISENTROPIC LIFT STRENGTHENS. HAVE INCREASED POPS FOR TODAY AND TONIGHT. THIS WARM AND MOIST AIR MASS WILL RIDE UP AND OVER THE COLDER AIR AT THE SURFACE...LEAVING THE BOUNDARY TO THE SOUTH. HOWEVER...AS THE WARM ADVECTION INTENSIFIES...THE FRONTAL BOUNDARY WILL BEGIN TO LIFT NORTHWARD THIS EVENING...ALTHOUGH HOW FAR NORTH IS STILL A BIG QUESTION. IN ANY CASE...DONT EXPECT TEMPERATURES TO DROP MUCH TONIGHT...AND ACROSS MOST OF THE AREA..TEMPERATURES WILL ACTUALLY CLIMB SUBSTANTIALLY OVERNIGHT. 07 .LONG TERM... A COLD AND UNSETTLED PATTERN WILL CONTINUE THROUGH MUCH OF THE EXTENDED FORECAST. A MODEST WARM UP CAN BE EXPECTED ON SATURDAY AS WARM FRONT LIFTS NORTH THROUGH WEST CENTRAL TEXAS. HIGH TEMPERATURES WILL RANGE FROM NEAR 60 NORTH...TO NEAR 70 SOUTH. IN THE MEANTIME...A LARGE UPPER LEVEL TROUGH WILL BE LOCATED ACROSS THE DESERT SOUTHWEST...AND AN ARCTIC COLD FRONT WILL BE LOCATED OVER THE SOUTHERN PLAINS. AN UPPER LEVEL SHORTWAVE TROUGH WILL TRACK ACROSS THE NORTHERN PLAINS SATURDAY HELPING TO SEND THIS COLD FRONT THROUGH WEST CENTRAL TEXAS SATURDAY NIGHT. SHOWERS WILL BE POSSIBLE ALONG AND AHEAD OF THE BOUNDARY...AND THIS IS REFLECTED IN THE CURRENT GRIDS. COLD AIR ADVECTION...CLOUD COVER AND LIGHT RAIN WILL HELP TO KEEP TEMPERATURES DOWN ON SUNDAY. DROPPED HIGH TEMPERATURES A FEW DEGREES...GENERALLY IN THE UPPER 30S TO MID 40S...AND THESE MAY NEED TO BE LOWERED ON FUTURE SHIFTS. ON SUNDAY NIGHT...AFOREMENTIONED UPPER LEVEL TROUGH REMAINS ACROSS THE DESERT SOUTHWEST...WHILE ANOTHER UPPER LEVEL SHORTWAVE TROUGH SKIRTS ACROSS THE CENTRAL PLAINS. THIS WILL HELP TO SEND A REINFORCING SHOT OF COLDER AIR INTO THE AREA...WITH NORTH WINDS INCREASING MONDAY MORNING AND COLD AIR FILTERING IN. IN ADDITION...UPPER LEVEL DISTURBANCES WILL CONTINUE TO MOVE ACROSS THE AREA IN ADVANCE OF THE MAIN UPPER LEVEL TROUGH LOCATED OVER THE SOUTHWEST STATES. THIS WILL LIKELY PRODUCE LIGHT PRECIPITATION ACROSS THE AREA SUNDAY NIGHT AND MONDAY. THE MAIN QUESTION THEN BECOMES...WHAT TYPE OF PRECIPITATION. MODEL SOUNDINGS AND 700MB/850MB TEMPERATURES ARE INDICATING A RAIN/SNOW MIX ACROSS THE NORTHERN HALF OF THE AREA EARLY MONDAY...THEN TRANSITIONING TO RAIN/SNOW ACROSS MUCH OF THE AREA BY LATE MONDAY...AND MOSTLY SNOW ACROSS THE NORTHERN COUNTIES. THIS SCENARIO IS REFLECTED IN THE CURRENT FORECAST PACKAGE. AT THIS TIME ANY ACCUMULATIONS SHOULD BE LIGHT...BUT A LOT OF UNCERTAINTY REMAINS IN THE AMOUNT OF PRECIPITATION AND THE PRECIPITATION TYPE SUNDAY AND MONDAY. HIGH TEMPERATURES ON MONDAY WILL BE WELL BELOW NORMAL...RANGING FROM THE MID 30S NORTH...TO NEAR 40 SOUTH. GIVEN THE FRIGID AIRMASS AND EXPECTED CLOUD COVER...THE CURRENT HIGH TEMPERATURES IN THE FORECAST MAY BE A BIT HIGH. MODELS CONTINUE TO HANG THE UPPER LEVEL TROUGH WEST OF THE AREA...BEFORE FINALLY SWINGING IT THROUGH LATE TUESDAY. INTRODUCED SLIGHT CHANCE POPS ACROSS THE AREA MONDAY NIGHT...BEFORE CONDITIONS IMPROVE TUESDAY MORNING. ANY PRECIPITATION THAT DOES OCCUR WILL LIKELY FALL AS LIGHT SNOW. ANOTHER VERY COLD DAY IS LIKELY ON TUESDAY...AND DROPPED TEMPERATURES A FEW DEGREES. A SLOW WARM UP WILL ENSUE BY THE MIDDLE OF NEXT WEEK...WITH CLOSER TO NORMAL TEMPERATURES RETURNING BY THURSDAY. DANIELS && .PRELIMINARY POINT TEMPS/POPS... ABILENE 38 38 63 32 39 / 60 60 60 20 30 SAN ANGELO 44 44 66 35 42 / 50 60 50 20 20 JUNCTION 55 55 69 40 44 / 40 60 40 50 40 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 07/DANIELS
AREA FORECAST DISCUSSION...UPDATED
NWS GREEN BAY WI
813 PM CST SAT DEC 3 2011 .UPDATED...CONCERNING HEADLINES. AVAILABLE REPORTS IN THE ADVISORY AREA SO FAR THIS EVENING RANGE UP TO 2 INCHES. IR LOOP SHOWS BEST ENHANCEMENT HAS QUICKLY SHIFTED NORTHEASTWARD INTO UPPER MICHIGAN. RADAR AND OBS ACROSS THE REGION INDICATE THE RAIN SNOW LINE EXTENDS FROM NORTHWEST IOWA TO RST TO STE TO JUST SOUTH OF IMT. A SURFACE LOW WAS OVER SOUTHERN IOWA EARLY THIS EVENING AND WILL BE ENTERING SOUTHWEST WISCONSIN LATE THIS EVENING AND NEARLY TRACKING ALONG THE RAIN SNOW LINE OVERNIGHT. A LARGE AREA OF RAIN WAS IN THE WARM SECTOR OF THE LOW OVER IOWA AND SOUTHERN WISCONSIN MOVING TOWARD EASTERN WISCONSIN. PARTS OF EASTERN WISCONSIN MAY SEE UP TO AN ADDITIONAL INCH OF RAIN OVERNIGHT. BUT BACK TO THE ADVISORY...BEST SNOW GROWTH REGION WAS OVER NORTHWEST WISCONSIN AND MAY INCLUDE WESTERN PORTIONS OF ONEIDA AND VILAS COUNTIES. THIS SNOW GROWTH REGION IS PROGGED TO SAG INTO NORTH CENTRAL WISCONSIN OVERNIGHT AS THE H8 LOW AND SURFACE LOW TRACKS OVER. NOT OUT OF THE QUESTION A WARNING MAY BE NEEDED AS THESE MORE FAVORABLE DYNAMICS PLAY A ROLE...BUT FOR NOW WILL CONTINUE THE HIGH END ADVISORY. TDH && .PREV DISCUSSION...ISSUED AT 505 PM CST SAT DEC 3 2011... SHORT TERM...TONIGHT AND SUNDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A DEVELOPING LOW PRESSURE SYSTEM MOVING NORTHEAST OVER SOUTH-CENTRAL KANSAS JUST AHEAD OF A SHORTWAVE TROUGH. ATTACHED TO THE SURFACE LOW TO THE NORTHEAST RUNS A COLD FRONT OVER CENTRAL IOWA INTO NORTHWEST WISCONSIN. FIRST BATCH OF PRECIP IS RIDING ALONG THE 850MB BAROCLINIC ZONE OVER THE SOUTHEASTERN HALF OF WISCONSIN THOUGH SOME BREAKS ARE SPREADING OVER EASTERN IOWA AND NORTHERN ILLINOIS...THAT MAY SPELL A BREAK IN THE PRECIP FOR A BRIEF PERIOD LATE THIS AFTERNOON OVER E-C WISCONSIN. THE MAIN AXIS OF PRECIP...HOWEVER... EXISTS JUST TO THE EAST OF THE SURFACE LOW ON THE NOSE OF A 60 KT LLJ AND UPPER DIVERGENT AREA WITHIN THE COUPLED JET. SOME HIGHER REFLECTIVITIES ARE ALSO DEVELOPING OVER WESTERN WISCONSIN WITHIN A STRENGTHENING FGEN ZONE...SO WILL JUST START THE WINTER HEADLINES WITH THE AFTERNOON PACKAGE. AS THE LOW TRACKS NORTHEAST OVER THE NEXT 24 HOURS...THE OBVIOUS CONCERNS ARE SNOW AMOUNTS AND HEADLINES. TONIGHT...FOLLOWED A SREF/GFS BLEND TONIGHT...WHICH SPLITS THE DIFFERENCE BETWEEN THE STRONGER NAM AND WEAKER ECMWF WHILE KEEPING THE CONSENSUS TRACK. LOW PRESSURE OVER THE CENTRAL PLAINS WILL RAPIDLY MOVE NE TOWARDS THE MID-MISSISSIPPI VALLEY THIS EVENING...AND NORTHERN LAKE MICHIGAN BY 12Z SUNDAY. AHEAD OF THE LOW...A BEEFY LLJ WILL SHIFT INTO SOUTHERN WISCONSIN THIS EVENING...THEREBY INCREASING CONVERGENCE ALONG THE STALLED BAROCLINIC ZONE STRETCHING ACROSS THE STATE...AND 850-700MB FGEN IN THE PROCESS. COMBINED WITH STRONG QG FORCING FROM SHORTWAVE ENERGY AND A WIDE OPEN GULF (PWATS 150-200 PCT OF NORMAL)...THE BEEFY SLUG OF PRECIP OVER THE PLAINS WILL HAVE NO TROUBLE SPREADING ACROSS THE STATE THIS EVENING. PTYPE REMAINS PROBLEMATIC AS THE 12Z MODEL RUNS HAVE TRENDED SLIGHTLY WARMER WITH THE THERMAL PROFILE AS THE LOW PUSHES WARMER AIR ALOFT SLIGHTLY FARTHER NORTH THAN PREVIOUS RUNS. THIS WILL PLACE THE RAIN-SNOW MIX AREA FROM WOOD COUNTY TO NORTHERN OCONTO AND MARINETTE. NORTH OF THE RAIN-SNOW LINE SHOULD RESIDE THE AXIS OF HEAVIEST SNOWFALL...WHICH LINES UP WITH THE EXTRAPOLATED SOUTHERN EDGE OF THE COMMA HEAD FROM APPROX MERRILL TO CRANDON. WITH SLIGHTLY COLDER AIR IN PLACE COMPARED TO THE FIRST SNOW STORM IN NOVEMBER...SNOW RATIOS WILL RUN BETWEEN 10-14:1 OVER THIS AREA ACCORDING TO THE COBB SNOWFALL ALGORITHM. WITH QPFS AROUND 0.4 TO 0.5 INCHES...THIS AMOUNTS TO A GOOD 4-6 INCH SWATH OF SNOW TONIGHT (5 TO 7 INCHES OVERALL)...THOUGH THE BULK OF THE PRECIP WILL LIKELY FALL THIS EVENING. THE FOX VALLEY AND LAKESHORE WILL RESIDE WITHIN THE WARM SECTOR OF THE STORM...WHICH MEANS MOSTLY RAIN TONIGHT...THOUGH SOME SNOW MAY MIX IN LATE. ENTERTAINED SOME THOUGHTS OF UPGRADING TO A WARNING GIVEN THE HEAVY SNOW OBS UPSTREAM...BUT GIVEN THE RELATIVELY LOW IMPACT OF THE SNOW (DURING THE NIGHT ON A WEEKEND)...WILL STICK WITH ADVISORY HEADLINES. ALSO THOUGHT ABOUT TRIMMING THE ADVISORY TO THE NW BY A ROW OF COUNTIES...BUT COORDINATION WITH SURROUNDING OFFICES YIELDED A RELUCTANCE...DUE TO THE SLOPPINESS OF THE MIX AND POTENTIAL FOR FREEZING DRIZZLE. AS A RESULT...WILL KEEP CURRENT HEADLINES AS THEY CURRENTLY STAND BUT STRESS THE HEAVY SNOWFALL RATES ARRIVING THIS EVENING. SUNDAY...THE LOW PRESSURE WILL QUICKLY EXIT TO SOUTHEAST ONTARIO BY 18Z SUNDAY BUT WILL HAVE THE BACK EDGE OF THE COMMA HEAD SHIFTING NE OVER N-C AND FAR NORTHEAST WISCONSIN. SOME MID-LEVEL FGEN WILL LINGER WHICH WILL RESULT IN ANOTHER HALF INCH TO AN INCH OVER N-C WISCONSIN EARLY IN THE MORNING. BUT OTHERWISE...SNOW WILL BE TAPERING DOWN TO JUST FLURRIES IN THE MORNING...WHILE COLDER AIR FILTERS ACROSS THE REGION. LOW LEVEL TROUGHINESS AND CYCLONIC FLOW WILL HANG AROUND FOR MUCH OF THE DAY...SO NOT ANTICIPATING MUCH CLEARING TOMORROW. HIGHS MAINLY IN THE LOW TO MIDDLE 30S. LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY...THE MAIN FCST CONCERNS WILL BE MINOR LAKE EFFECT SNOW POTENTIAL OVER NORTHERN WI EARLY IN THE PERIOD...THEN THE POTENTIAL FOR SNOW AND MUCH COLDER TEMPERATURES WITH AN ARCTIC FRONTAL PASSAGE LATE NEXT WEEK. A STRONG...HIGH AMPLITUDE RIDGE WILL COVER THE EASTERN PACIFIC... WESTERN CANADA AND THE WEST COAST OF THE U.S. EARLY IN THE PERIOD... WITH A POSITIVELY-TILTED UPPER TROF EXTENDING FROM CENTRAL CANADA INTO THE SOUTHWEST UNITED STATES. THIS UPPER TROF WILL MOVE THROUGH WISCONSIN ON TUESDAY...WITH LITTLE IMPACT ON OUR WEATHER. SHORT-WAVE ENERGY WILL TOP THE WESTERN RIDGE EARLY NEXT WEEK...THEN EVENTUALLY HELP TO CARVE A BROAD TROF OVER THE CENTRAL U.S. BY THU/FRI. A SURGE OF ARCTIC AIR IS EXPECTED TO ARRIVE IN WI LATE IN THE WEEK... WITH H8 TEMPS PLUMMETING TO AROUND -20 C. THIS WILL LEAD TO OUR COLDEST TEMPERATURES SO FAR THIS SEASON. A LARGE RIDGE OF HIGH PRESSURE WILL BE CENTERED OVER THE NORTHERN ROCKIES AND NORTHERN PLAINS SUN NGT INTO MON...WITH COLD NORTH FLOW RESULTING IN SCT LAKE-EFFECT SNOW SHOWERS OVER MAINLY NC WI. THE SNOW SHOWERS MAY LINGER INTO MONDAY NIGHT...BUT SHOULD COME TO AN END ON TUESDAY AS THE RIDGE AXIS PUSHES ACROSS WI. A WEAK COLD FRONT IS EXPECTED TO MOVE THROUGH THE REGION ON WEDNESDAY...WITH A STRONGER ARCTIC FRONT ARRIVING SOMETIME DURING THE THU/FRI TIME FRAME. DURING THIS PERIOD...LLVL FLOW IS EXPECTED TO BE TOO WESTERLY FOR LK-EFFECT. THE ECMWF AND A FEW OF THE GFS ENSEMBLE MEMBERS SUGGEST THAT A SFC WAVE WILL DEVELOP ALONG THE ARCTIC BOUNDARY LATE IN THE WEEK...AS THE RRQ OF A STRONG UPPER LEVEL JET PULLS THROUGH THE REGION. IF THIS PLAYS OUT...WE COULD BRING SEE SEVERAL INCHES OF POWDERY SNOW SOMETIME DURING THE THURSDAY NIGHT TO SATURDAY PERIOD. FOR NOW...WILL FOLLOW THE CONCENSUS OF AREA OFFICES...AND JUST MENTION SMALL POPS ACROSS OUR SOUTHERN AND EASTERN COUNTIES ON THU NGT/FRI. THERE IS A HIGHER DEGREE OF CONFIDENCE IN A TREND TOWARD MUCH COLDER TEMPERATURES LATE IN THE WEEK...ALTHOUGH THE NEW ECMWF IS SLOWER WITH THE TIMING OF THE ARCTIC BOUNDARY. SUBSEQUENT FCSTS SHOULD BE BETTER ABLE TO PINPOINT THE FRONTAL TIMING AND SNOWFALL POTENTIAL LATE NEXT WEEK. && .AVIATION...RAIN SNOW LINE ROUGHLY FROM STE TO IMT LATE THIS AFTERNOON WILL CHANGE LITTLE EARLY THIS EVENING AS THE SURFACE AND H8 LOW TRACK NORTHEAST OVER THE STATE. SOME OBSERVATIONS AT 1/4 MILE OVER CENTRAL WISCONSIN BUT CAMERAS INDICATE FOG WITH SNOW VS HEAVY SNOW. NEVERTHELESS LIFR CIGS ALONG WITH IFR VSBYS WITH SCATTERED LIFR VSBYS WILL CONTINUE TONIGHT. BRUNT OF THE ACCUMULATING SNOW TO IMPACT CENTRAL AND NORTH CENTRAL TONIGHT. CIGS AND VSBYS TO IMPROVE TO MVFR LEVELS SUNDAY AS THE SYSTEM DEPARTS TO THE NORTHEAST SUNDAY MORNING. TDH && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR WIZ005-010>013- 018-019-021-030-035. && $$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
505 PM CST SAT DEC 3 2011 UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE .SHORT TERM...TONIGHT AND SUNDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A DEVELOPING LOW PRESSURE SYSTEM MOVING NORTHEAST OVER SOUTH-CENTRAL KANSAS JUST AHEAD OF A SHORTWAVE TROUGH. ATTACHED TO THE SURFACE LOW TO THE NORTHEAST RUNS A COLD FRONT OVER CENTRAL IOWA INTO NORTHWEST WISCONSIN. FIRST BATCH OF PRECIP IS RIDING ALONG THE 850MB BAROCLINIC ZONE OVER THE SOUTHEASTERN HALF OF WISCONSIN THOUGH SOME BREAKS ARE SPREADING OVER EASTERN IOWA AND NORTHERN ILLINOIS...THAT MAY SPELL A BREAK IN THE PRECIP FOR A BRIEF PERIOD LATE THIS AFTERNOON OVER E-C WISCONSIN. THE MAIN AXIS OF PRECIP...HOWEVER... EXISTS JUST TO THE EAST OF THE SURFACE LOW ON THE NOSE OF A 60 KT LLJ AND UPPER DIVERGENT AREA WITHIN THE COUPLED JET. SOME HIGHER REFLECTIVITIES ARE ALSO DEVELOPING OVER WESTERN WISCONSIN WITHIN A STRENGTHENING FGEN ZONE...SO WILL JUST START THE WINTER HEADLINES WITH THE AFTERNOON PACKAGE. AS THE LOW TRACKS NORTHEAST OVER THE NEXT 24 HOURS...THE OBVIOUS CONCERNS ARE SNOW AMOUNTS AND HEADLINES. TONIGHT...FOLLOWED A SREF/GFS BLEND TONIGHT...WHICH SPLITS THE DIFFERENCE BETWEEN THE STRONGER NAM AND WEAKER ECMWF WHILE KEEPING THE CONSENSUS TRACK. LOW PRESSURE OVER THE CENTRAL PLAINS WILL RAPIDLY MOVE NE TOWARDS THE MID-MISSISSIPPI VALLEY THIS EVENING...AND NORTHERN LAKE MICHIGAN BY 12Z SUNDAY. AHEAD OF THE LOW...A BEEFY LLJ WILL SHIFT INTO SOUTHERN WISCONSIN THIS EVENING...THEREBY INCREASING CONVERGENCE ALONG THE STALLED BAROCLINIC ZONE STRETCHING ACROSS THE STATE...AND 850-700MB FGEN IN THE PROCESS. COMBINED WITH STRONG QG FORCING FROM SHORTWAVE ENERGY AND A WIDE OPEN GULF (PWATS 150-200 PCT OF NORMAL)...THE BEEFY SLUG OF PRECIP OVER THE PLAINS WILL HAVE NO TROUBLE SPREADING ACROSS THE STATE THIS EVENING. PTYPE REMAINS PROBLEMATIC AS THE 12Z MODEL RUNS HAVE TRENDED SLIGHTLY WARMER WITH THE THERMAL PROFILE AS THE LOW PUSHES WARMER AIR ALOFT SLIGHTLY FARTHER NORTH THAN PREVIOUS RUNS. THIS WILL PLACE THE RAIN-SNOW MIX AREA FROM WOOD COUNTY TO NORTHERN OCONTO AND MARINETTE. NORTH OF THE RAIN-SNOW LINE SHOULD RESIDE THE AXIS OF HEAVIEST SNOWFALL...WHICH LINES UP WITH THE EXTRAPOLATED SOUTHERN EDGE OF THE COMMA HEAD FROM APPROX MERRILL TO CRANDON. WITH SLIGHTLY COLDER AIR IN PLACE COMPARED TO THE FIRST SNOW STORM IN NOVEMBER...SNOW RATIOS WILL RUN BETWEEN 10-14:1 OVER THIS AREA ACCORDING TO THE COBB SNOWFALL ALGORITHM. WITH QPFS AROUND 0.4 TO 0.5 INCHES...THIS AMOUNTS TO A GOOD 4-6 INCH SWATH OF SNOW TONIGHT (5 TO 7 INCHES OVERALL)...THOUGH THE BULK OF THE PRECIP WILL LIKELY FALL THIS EVENING. THE FOX VALLEY AND LAKESHORE WILL RESIDE WITHIN THE WARM SECTOR OF THE STORM...WHICH MEANS MOSTLY RAIN TONIGHT...THOUGH SOME SNOW MAY MIX IN LATE. ENTERTAINED SOME THOUGHTS OF UPGRADING TO A WARNING GIVEN THE HEAVY SNOW OBS UPSTREAM...BUT GIVEN THE RELATIVELY LOW IMPACT OF THE SNOW (DURING THE NIGHT ON A WEEKEND)...WILL STICK WITH ADVISORY HEADLINES. ALSO THOUGHT ABOUT TRIMMING THE ADVISORY TO THE NW BY A ROW OF COUNTIES...BUT COORDINATION WITH SURROUNDING OFFICES YIELDED A RELUCTANCE...DUE TO THE SLOPPINESS OF THE MIX AND POTENTIAL FOR FREEZING DRIZZLE. AS A RESULT...WILL KEEP CURRENT HEADLINES AS THEY CURRENTLY STAND BUT STRESS THE HEAVY SNOWFALL RATES ARRIVING THIS EVENING. SUNDAY...THE LOW PRESSURE WILL QUICKLY EXIT TO SOUTHEAST ONTARIO BY 18Z SUNDAY BUT WILL HAVE THE BACK EDGE OF THE COMMA HEAD SHIFTING NE OVER N-C AND FAR NORTHEAST WISCONSIN. SOME MID-LEVEL FGEN WILL LINGER WHICH WILL RESULT IN ANOTHER HALF INCH TO AN INCH OVER N-C WISCONSIN EARLY IN THE MORNING. BUT OTHERWISE...SNOW WILL BE TAPERING DOWN TO JUST FLURRIES IN THE MORNING...WHILE COLDER AIR FILTERS ACROSS THE REGION. LOW LEVEL TROUGHINESS AND CYCLONIC FLOW WILL HANG AROUND FOR MUCH OF THE DAY...SO NOT ANTICIPATING MUCH CLEARING TOMORROW. HIGHS MAINLY IN THE LOW TO MIDDLE 30S. .LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY...THE MAIN FCST CONCERNS WILL BE MINOR LAKE EFFECT SNOW POTENTIAL OVER NORTHERN WI EARLY IN THE PERIOD...THEN THE POTENTIAL FOR SNOW AND MUCH COLDER TEMPERATURES WITH AN ARCTIC FRONTAL PASSAGE LATE NEXT WEEK. A STRONG...HIGH AMPLITUDE RIDGE WILL COVER THE EASTERN PACIFIC... WESTERN CANADA AND THE WEST COAST OF THE U.S. EARLY IN THE PERIOD... WITH A POSITIVELY-TILTED UPPER TROF EXTENDING FROM CENTRAL CANADA INTO THE SOUTHWEST UNITED STATES. THIS UPPER TROF WILL MOVE THROUGH WISCONSIN ON TUESDAY...WITH LITTLE IMPACT ON OUR WEATHER. SHORT-WAVE ENERGY WILL TOP THE WESTERN RIDGE EARLY NEXT WEEK...THEN EVENTUALLY HELP TO CARVE A BROAD TROF OVER THE CENTRAL U.S. BY THU/FRI. A SURGE OF ARCTIC AIR IS EXPECTED TO ARRIVE IN WI LATE IN THE WEEK... WITH H8 TEMPS PLUMMETING TO AROUND -20 C. THIS WILL LEAD TO OUR COLDEST TEMPERATURES SO FAR THIS SEASON. A LARGE RIDGE OF HIGH PRESSURE WILL BE CENTERED OVER THE NORTHERN ROCKIES AND NORTHERN PLAINS SUN NGT INTO MON...WITH COLD NORTH FLOW RESULTING IN SCT LAKE-EFFECT SNOW SHOWERS OVER MAINLY NC WI. THE SNOW SHOWERS MAY LINGER INTO MONDAY NIGHT...BUT SHOULD COME TO AN END ON TUESDAY AS THE RIDGE AXIS PUSHES ACROSS WI. A WEAK COLD FRONT IS EXPECTED TO MOVE THROUGH THE REGION ON WEDNESDAY...WITH A STRONGER ARCTIC FRONT ARRIVING SOMETIME DURING THE THU/FRI TIME FRAME. DURING THIS PERIOD...LLVL FLOW IS EXPECTED TO BE TOO WESTERLY FOR LK-EFFECT. THE ECMWF AND A FEW OF THE GFS ENSEMBLE MEMBERS SUGGEST THAT A SFC WAVE WILL DEVELOP ALONG THE ARCTIC BOUNDARY LATE IN THE WEEK...AS THE RRQ OF A STRONG UPPER LEVEL JET PULLS THROUGH THE REGION. IF THIS PLAYS OUT...WE COULD BRING SEE SEVERAL INCHES OF POWDERY SNOW SOMETIME DURING THE THURSDAY NIGHT TO SATURDAY PERIOD. FOR NOW...WILL FOLLOW THE CONCENSUS OF AREA OFFICES...AND JUST MENTION SMALL POPS ACROSS OUR SOUTHERN AND EASTERN COUNTIES ON THU NGT/FRI. THERE IS A HIGHER DEGREE OF CONFIDENCE IN A TREND TOWARD MUCH COLDER TEMPERATURES LATE IN THE WEEK...ALTHOUGH THE NEW ECMWF IS SLOWER WITH THE TIMING OF THE ARCTIC BOUNDARY. SUBSEQUENT FCSTS SHOULD BE BETTER ABLE TO PINPOINT THE FRONTAL TIMING AND SNOWFALL POTENTIAL LATE NEXT WEEK. && .AVIATION...RAIN SNOW LINE ROUGHLY FROM STE TO IMT LATE THIS AFTERNOON WILL CHANGE LITTLE EARLY THIS EVENING AS THE SURFACE AND H8 LOW TRACK NORTHEAST OVER THE STATE. SOME OBSERVATIONS AT 1/4 MILE OVER CENTRAL WISCONSIN BUT CAMERAS INDICATE FOG WITH SNOW VS HEAVY SNOW. NEVERTHELESS LIFR CIGS ALONG WITH IFR VSBYS WITH SCATTERED LIFR VSBYS WILL CONTINUE TONIGHT. BRUNT OF THE ACCUMULATING SNOW TO IMPACT CENTRAL AND NORTH CENTRAL TONIGHT. CIGS AND VSBYS TO IMPROVE TO MVFR LEVELS SUNDAY AS THE SYSTEM DEPARTS TO THE NORTHEAST SUNDAY MORNING. TDH && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR WIZ005-010>013- 018-019-021-030-035. && $$
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
329 PM CST FRI DEC 2 2011 .SHORT TERM... TONIGHT AND SATURDAY...FORECAST CONFIDENCE MEDIUM TO HIGH SHORTWAVE ENERGY EJECTING OUT OF A TROUGH IN THE SOUTHWEST U.S. WILL BRING A PLUME OF MOISTURE INTO WISCONSIN TONIGHT THROUGH SUNDAY MORNING. THIS PLUME IS APPARENT IN THE LATEST WATER VAPOR IMAGERY. THIS TROUGH/SHORTWAVE WILL PHASE WITH A NORTHERN STREAM TROUGH OVER THE WEEKEND...CREATING A PROLONGED PRECIP EVENT ACROSS WISCONSIN. MODELS ARE IN FAIR AGREEMENT ABOUT WAITING UNTIL AFTER MIDNIGHT FOR THE WALL OF WATER...OR DEEP MOISTURE...TO REACH SOUTH CENTRAL WI. WHILE THERE MAY BE SOME PRECIP IN THE FORECAST AREA BEFORE 3 AM...THE MAIN SURGE WILL HIT MOST OF THE AREA BETWEEN 3 AND 6 AM. THE PRECIP MAY HOLD OFF IN KENOSHA AND MILWAUKEE UNTIL RIGHT AROUND 6 AM/12Z. UPPER LEVEL DIVERGENCE INCREASES TONIGHT ALONG WITH MODERATE 700MB UPWARD MOTION. ISENTROPIC LIFT SEEN ON THE 290K ISENTROPIC LEVEL WITH CONDENSATION PRESSURE DEFICITS BELOW 5 MB ON THE NAM BY SUNRISE SATURDAY. PRECIP WILL MAINLY BE IN THE FORM OF RAIN IN THE ENTIRE FORECAST AREA. THE ONLY EXCEPTION WILL BE AROUND THE DELLS AND GREEN LAKE/MARQUETTE COUNTIES WHERE THE EVENT COULD BEGIN AS SNOW AND SWITCH TO RAIN. WITH THE STRONG WARM AIR ADVECTION...SFC TEMPS ARE EXPECTED TO WARM TO JUST ABOVE FREEZING WITH THE ONSET OF PRECIPITATION...THUS LIMITING THE FREEZING RAIN OR SNOW POTENTIAL. THE CENTER OF THE SURFACE LOW PRESSURE WILL TRACK RIGHT ACROSS SOUTH CENTRAL WI LATE SAT AFTERNOON INTO SUNDAY MORNING...SO A LULL IN THE PRECIPITATION IS EXPECTED IN SOUTHEAST WI...EAST OF MADISON. THE LULL SHOULD BE FROM AROUND 2 PM SAT THROUGH SAT EVENING IN MILWAUKEE. CLOUD COVER DURING THIS TIME IS UNCERTAIN...AS MODELS SUGGEST CLEARING AND EXPERIENCE SUGGESTS STRATUS CLOUDS AND POSSIBLY LIGHT FOG. SATURDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE MEDIUM TO HIGH THE SHORTWAVE TROUGH LIFTING NEWD THROUGH THE GREAT PLAINS WILL REACH NRN WI BY 12Z SUN AND WILL AID IN MINOR DEEPENING OF THE SFC LOW AS IT TRACKS FROM ERN KS TO SE WI. A DRY SLOT WILL INITIALLY BE OVER ERN WI SAT EVENING BUT WILL SHIFT EWD WITH A 60 KT LOW LEVEL JET STREAM TO BRING A NEW SURGE OF WARM AND MOIST ADVECTION AND SFC-850 MB FRONTOGENESIS. PWS TO INCREASE TO 0.80-0.90 INCHES WITH WIDESPREAD MDT RAIN EXPECTED. THE CONSENSUS OF THE THERMAL FIELDS WILL BRING A MIXTURE OF LGT RAIN AND LGT SNOW TO THE FAR WRN CWA BETWEEN 09-12Z. PCPN TO QUICKLY DIMINISH SUN AM AS THE LOW LEVEL JET STREAM SHIFTS INTO LOWER MI. LIKELY POPS EXPECTED EARLY IN THE DAY FOR THE NE CWA WITH CHANCES ELSEWHERE. LGT RAIN WILL CHANGE TO OR MIX WITH LGT SNOW BUT SNOW ACCUMULATIONS WILL LIKELY REMAIN UNDER ONE HALF INCH IN THE NRN AND WRN CWA WITH TRACE AMOUNTS AT BEST IN SE WI. COLD AND DRY ADVECTION AND SUBSIDENCE SHOULD BE ENOUGH FOR CLOUD COVER TO BECOME FEW-SCATTERED FOR SUN NT INTO MONDAY. A WEAKENING LOW PRESSURE AREA AND SHORTWAVE TROUGH WILL THEN MOVE FROM THE NRN PLAINS INTO THE GREAT LAKES FOR MONDAY. THE ONLY RESULT WILL BE A DRY COLD FRONT WITH THE UPSTREAM POLAR HIGH OVER THE NRN AND CENTRAL GREAT PLAINS. .LONG TERM... TUESDAY THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM A HIGH PRESSURE RIDGE ASSOCIATED WITH THE POLAR HIGH OVER THE CENTRAL PLAINS WILL MOVE ACROSS WI FOR TUE/TUE NT WHILE A LONG WAVE UPPER TROUGH AND SFC TROUGH BRINGS PCPN TO SRN AND ERN UNITED STATES. FOR THE REMAINDER OF THE WEEK A STRONG AND VERY LARGE CYCLONE WILL MOVE ACROSS NRN CANADA AND OCCLUDE OVER AND NORTH OF THE HUDSON BAY AREA LATER IN THE WEEK. THE NRN USA WILL BE ON THE SRN FRINGES OF THIS CYCLONE WITH DRY WNWLY WINDS AND GRADUAL COLD ADVECTION. DURING THIS TIME A 1040 MB ARCTIC HIGH WILL SLIDE SWD ALONG THE LEE OF THE CANADIAN ROCKIES AND EVENTUALLY INTO THE MID MO RIVER VALLEY ON FRI. SLIGHTLY BELOW NORMAL TEMPS ARE EXPECTED LATER NEXT WEEK WITH THE LACK OF SNOW COVER INHIBITING GREATER COOLING. && .AVIATION/00Z TAFS/... CLEAR SKIES THROUGH THE EVENING UNDER THE HIGH PRESSURE. HOWEVER SOUTH WINDS DEVELOPING AHEAD OF LOW PRESSURE FROM WESTERN OKLAHOMA TO MINNESOTA WILL BRING INCREASING/THICKENING AND LOWERING HIGH/MID LEVEL CLOUDS THIS EVENING...FOLLOWED BY MVFR/IFR CIGS AND VSBYS... ESPECIALLY IN SOUTH CENTRAL WISCONSIN DURING THE EARLY MORNING HOURS SATURDAY. SOME FREEZING RAIN POTENTIAL MAINLY NORTH AND WEST OF MADISON TO NEAR FOND DU LAC. THERE WILL BE A LULL IN THE PRECIP SAT AFTERNOON. NOT SURE IF CEILINGS WILL TANK WITHIN THE LULL AS THE SFC LOW MOVES OVERHEAD DURING THIS TIME. LOW CIGS EXPECTED EARLY SAT EVENING...WHICH SHOULD COME UP A BIT WHEN THE NEXT ROUND OF PRECIP HITS. PRECIP TYPE SHOULD BE ALL RAIN FROM TONIGHT THROUGH SATURDAY NIGHT AT ALL TAF SITES. LOW LEVEL WIND SHEAR EXPECTED TONIGHT INTO SATURDAY MORNING AS LOW LEVEL JET MOVES OVERHEAD. NAM IS STRONGER WITH THE WINDS THAN THE GFS...AND RUC IS IN BETWEEN. LLWS WILL BE POSSIBLE ONCE AGAIN SAT NIGHT AS A NEW SURGE OF WARM AIR ADVECTION MOVES INTO SOUTHEAST WI. && .MARINE... SOUTH WINDS WILL INCREASE TONIGHT AND WINDS AND WAVES ARE EXPECTED TO REACH LOWER-END SMALL CRAFT ADVISORY CONDITIONS LATE TONIGHT INTO SATURDAY. WINDS AND WAVES WILL BE HIGH THROUGH SATURDAY MORNING...THEN THERE WILL BE A LULL IN THE WINDS SATURDAY AFTERNOON AS THE SURFACE LOW CROSSES SOUTHEAST WISCONSIN. WEST WINDS WILL INCREASE BEHIND THE LOW ONCE AGAIN SAT NIGHT THROUGH AT LEAST MIDDAY SUNDAY. A SMALL CRAFT ADVISORY IS IN EFFECT FROM 06Z TONIGHT THROUGH 18Z SUNDAY. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST SUNDAY FOR LMZ643>646. && $$ TONIGHT/SATURDAY AND AVIATION/MARINE...MRC SATURDAY NIGHT THROUGH FRIDAY...GEHRING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1131 AM CST FRI DEC 2 2011 .SHORT TERM...TODAY THROUGH SUNDAY NIGHT 347 AM CST FRI DEC 2 2011 MAIN FORECAST CONCERN IS ON PRECIPITATION FOR AFTER MIDNIGHT TONIGHT THROUGH SUNDAY MORNING AND POSSIBLE HAZARDS. CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A POTENT UPPER TROUGH OVER SOUTHWEST CANADA...RIDGING OUT AHEAD OVER THE NORTHERN PLAINS INTO MANITOBA...AND TROUGHING OVER THE LAKE MICHIGAN AREA. ALSO OF NOTE IS IN THE SOUTHERN STREAM OF AN UPPER LOW OVER THE DESERT SOUTHWEST. THE FORECAST AREA LIES IN SUBSIDENCE IMMEDIATELY BEHIND THE LAKE MICHIGAN TROUGH...PROMOTING HIGH PRESSURE AT THE SURFACE. IN FACT...THE SUBSIDENCE AND DRYING HAS BEEN ENOUGH TO RESULT IN CLEAR SKIES OVER THE AREA. UPSTREAM 00Z SOUNDINGS FROM INL AND ABR REFLECT THE DRYING WELL WITH PRECIPITABLE WATER VALUES UNDER TWO TENTHS OF AN INCH. THE COMBINATION OF THE CLEAR SKIES AND LIGHT WINDS HAS ALLOWED TEMPERATURES TO DROP INTO THE TEENS TO MID 20S. TO THE NORTHWEST...A STREAM OF UPPER LEVEL MOISTURE CAN BE SEEN ACROSS THE NORTHERN PLAINS INTO SOUTH CENTRAL CANADA ON WATER VAPOR....AHEAD OF THE UPPER TROUGH THERE...WHICH IS MANIFESTING ITSELF INTO A LARGE ALTOSTRATUS AND CIRROSTRATUS DECK. TO THE SOUTHWEST...850MB WINDS HAVE BEEN INCREASING OUT OF THE SOUTH OVER TEXAS DOWNSTREAM OF THE UPPER LOW...BRINGING GULF OF MEXICO MOISTURE NORTHWARD TOWARDS OKLAHOMA AS SEEN IN GOES PRECIPITABLE WATER PLOTS. TODAY AND TONIGHT...A WARM ADVECTION PATTERN LOOKS TO DEVELOP OVER THE AREA IN RESPONSE TO THE UPPER TROUGH OVER SOUTHWEST CANADA SPLITTING INTO TWO...WHERE ONE PIECE MARCHES EAST INTO NORTHWEST ONTARIO AND NORTH DAKOTA BY 12Z SATURDAY. THE OTHER PIECE DIGS SOUTH TOWARDS THE LAS VEGAS AREA...CAUSING THE CURRENT UPPER LOW IN ARIZONA TO GET PUSHED EAST INTO NEW MEXICO. CONDITIONS WILL REMAIN DRY TODAY GIVEN PLENTIFUL DRY AIR AROUND AS SEEN FROM 00Z SOUNDINGS. IN FACT...SKIES SHOULD STAY CLEAR TO 00Z. WINDS ARE LIKELY TO INCREASE...THOUGH...AS THE PRESSURE GRADIENT TIGHTENS UP BEHIND THE DEPARTING SURFACE RIDGE. TONIGHT IS A DIFFERENT STORY. THE SOUTHERLY RETURN FLOW SEEN OCCURRING OVER TEXAS NOW IS FORECAST TO EXPAND AND INTENSIFY TONIGHT...RUNNING FROM DEEP SOUTH TEXAS INTO KANSAS...THEN NORTHEAST INTO THE FORECAST AREA BY 06Z. 850MB WINDS IN THIS ZONE ARE PROGGED BETWEEN 40-50 KT. PRECIPITABLE WATER VALUES RESPOND BY JUMPING FROM AROUND 0.25 INCH AT 00Z TO 0.5-0.8 INCHES AT 12Z... HIGHEST IN THE SOUTHEASTERN PORTION OF THE FORECAST AREA. 0.75 INCHES REPRESENTS 200 PERCENT OF NORMAL. AS THE DEEPER MOISTURE ISENTROPICALLY LIFTS INTO THE COLDER AIRMASS OVER THE AREA... ANTICIPATING PRECIPITATION TO BREAK OUT. MODELS ARE IN VERY GOOD AGREEMENT ON THIS OCCURRING...WITH THE HIGHEST CONSENSUS OVER THE SOUTHEASTERN TWO-THIRDS OF THE AREA. PLACED 80-100 PERCENT CHANCES IN THE SOUTHEAST HALF...THEN TRENDED DRIER HEADING UP TO THE NORTHWEST INTO LOWER PRECIPITABLE WATER VALUES. P-TYPE A LITTLE TRICKY AS A SURGE OF WARMER AIR ALSO ACCOMPANIES THE MOISTURE SURGE. 850MB TEMPS ARE PROGGED TO WARM TO 0-2C OVER THE SAME AREA WITH THE HIGHEST PRECIPITABLE WATER. SHOULD BE MOSTLY A RAIN/SNOW SCENARIO AS SURFACE TEMPERATURES WARM OVERNIGHT...BUT COULD SEE FREEZING RAIN TOO IF SURFACE TEMPERATURES HAVE NOT WARMED ABOVE FREEZING OR FROM NOT ENOUGH ICE PRESENT ALOFT YET. ANY SNOW/ICE ACCUMULATION LOOKS MINIMAL TONIGHT. HAVE NOT INCLUDED ANY FREEZING RAIN/DRIZZLE BECAUSE UNCERTAINTY IS JUST TOO HIGH. SATURDAY THROUGH SUNDAY...MODELS ARE ALL IN VERY GOOD AGREEMENT KICKING OUT THE UPPER LOW FROM NEW MEXICO AT 12Z SATURDAY NORTHEAST AS A SHEARING OUT SHORTWAVE. IN ADDITION...THE SHORTWAVE SHOULD GET ACCELERATED NORTHEAST OVERNIGHT TONIGHT INTO SUNDAY IN RESPONSE TO MORE TROUGHING DROPPING SOUTH INTO THE NORTHERN PLAINS. THERE ARE SOME SLIGHT DIFFERENCES WITH RESPECT TO THE ASSOCIATED SURFACE LOW WITH THE SHORTWAVE...WHICH HAS IMPLICATIONS ON THE TRACK AND INTENSITY OF THE DEFORMATION PRECIPITATION ON THE NORTH SIDE OF THE LOW. THE 02.00Z GFS IS THE WEAKEST WITH THE LOW AND FURTHEST SOUTHEAST...HAVING IT TRACK ACROSS NORTHEAST ILLINOIS AT 12Z SUNDAY. THE 02.00Z NAM IS FARTHEST NORTHWEST AND FASTEST...CROSSING THE BAY OF GREEN BAY AT 12Z SUNDAY. THE 02.00Z ECMWF/UKMET IS A COMPROMISE. FOR NOW FOLLOWED THE COMPROMISE APPROACH...SINCE THE GFS SOLUTION IS PLAUSIBLE IF MORE CONVECTION CAN OCCUR THAN CURRENTLY PROGGED DOWN OVER THE SOUTHERN PLAINS. ON THE FLIP SIDE...THERE HAS BEEN QUITE A BIT OF CONSISTENCY WITH THE ECMWF AND NAM SOLUTIONS. SATURDAY MORNING SHOULD BE A CONTINUATION OF PRECIPITATION FROM AFTER MIDNIGHT TONIGHT...DUE TO PERSISTENT ISENTROPIC LIFT. PRECIPITATION THEN LOOKS TO INTENSIFY IN THE AFTERNOON...PARTICULARLY OVER THE NORTHWEST HALF OF THE FORECAST AREA...AS THE DEFORMATION AREA OF THE SURFACE LOW APPROACHES. HEAVIEST PRECIPITATION STILL LOOKS TO OCCUR SATURDAY EVENING WHEN STRONGEST LOW TO MID-LEVEL FRONTOGENESIS MOVES ACROSS. IN FACT...CROSS-SECTIONS SHOW THE PRESENCE OF SOME NEGATIVE EPV ON TOP OF THE FRONTOGENESIS ZONE...SUGGESTING CONVECTIVE ELEMENTS ARE POSSIBLE. AGAIN...THE HEAVIEST PRECIPITATION LOOKS TO END UP OVER THE NORTHWEST HALF OF THE FORECAST AREA. WITH SNOW TO WATER RATIOS LIKELY TO END UP SOMEWHERE AROUND 10 TO 1 AS AN AVERAGE FOR SATURDAY AND SATURDAY NIGHT...COMBINED WITH QPF AMOUNTS AROUND 0.60 OF AN INCH...TOTAL SNOWFALL WOULD COME OUT TO AROUND 6 INCHES. GIVEN THAT THE NORTHWEST HALF OF THE FORECAST AREA HAS NOT REALLY SEEN ITS FIRST SIGNIFICANT SNOW...HAVE ISSUED A WINTER STORM WATCH FOR THAT AREA. BIGGEST CONCERN OF THE WATCH IS SATURDAY AFTERNOON AND EVENING...ESPECIALLY TOO WITH THE HOLIDAY SHOPPING/TRAVEL TAKING PLACE. FOR THE SOUTHEAST END OF THE FORECAST AREA...MAJORITY OF THE PRECIPITATION MAY FALL AS RAIN OR A RAIN/SNOW MIX AS A SURGE OF WARM AIR COMES IN. NEW 02.06Z NAM SUGGESTS EVEN A WARMER SURGE. LA CROSSE COUNTY KEPT OUT OF THE WATCH DUE TO RAIN MIX EXPECTED ON SATURDAY. FOR BOTH SATURDAY AND SATURDAY NIGHT...INCREASED PRECIPITATION CHANCES ANYWHERE FROM 10 TO 30 PERCENT GIVEN GOOD CONTINUITY AND MODEL AGREEMENT. PRECIPITATION SHOULD DIMINISH PRETTY QUICK ON SUNDAY...THOUGH DID KEEP SOME 20 PERCENT CHANCES GOING IN THE AFTERNOON FOR CENTRAL WISCONSIN WITH LINGERING UPPER TROUGHING. CERTAINLY WILL BE COOLER ON SUNDAY WITH SNOW COVER AND 850MB TEMPS OF -6 TO -8C MOVING IN. SUNDAY NIGHT AND MONDAY...ATTENTION TURNS TO THE TROUGHING COMING INTO THE NORTHERN PLAINS ON SUNDAY. GOOD AGREEMENT ON THIS UPPER TROUGH HEADING EAST INTO THE FORECAST AREA ON MONDAY. HOWEVER...ALL OF THE BETTER FORCING/MOISTURE APPEAR TO HEAD TO THE NORTH OF THE AREA. AS SUCH...HAVE CONTINUED A DRY SUNDAY NIGHT AND ONLY KEPT A 20 PERCENT CHANCE IN FOR TAYLOR/CLARK COUNTIES ON MONDAY. COULD SEE CHANCES BEING COMPLETELY REMOVED FOR MONDAY IF TRENDS CONTINUE. ALTHOUGH PRECIPITATION LOOKS LIMITED...THE COLD AIR WILL NOT BE. 850MB TEMPS ARE PROGGED TO FALL EVEN FURTHER...DROPPING TO AT LEAST -8 TO -12C BY 00Z TUESDAY...IF NOT A LITTLE COOLER THAN THAT AS NOTED BY THE 02.00Z GFS. WENT WITH A BLEND OF GUIDANCE FOR LOWS AND HIGHS DURING THIS PERIOD...WHICH END UP 5 TO 10 DEGREES COLDER THAN SATURDAY NIGHT AND SUNDAY. .LONG TERM...MONDAY NIGHT THROUGH THURSDAY NIGHT 347 AM CST FRI DEC 2 2011 AFTER A BUSY EARLY PART TO THE WEEKEND FOR THE WEATHER...MUCH OF THE EARLY AND MIDDLE PORTION OF NEXT WEEK LOOK QUIET AND COOL. 02.00Z ECMWF/CANADIAN/GFS/GFS ENSEMBLES ARE IN GOOD AGREEMENT FOR MUCH OF THE LONG TERM FORECAST INDICATING THE TROUGHING THAT WAS OVER THE AREA MONDAY LINGERING INTO TUESDAY...THEN JUST GRADUAL DEEP TROUGHING FORMING OVER MUCH OF CANADA INTO THE NORTHERN U.S. HEADING INTO THURSDAY. THIS TYPE OF PATTERN SUGGESTS LITTLE MOISTURE TO WORK WITH AND AS SUCH MODEL QPF FORECASTS ARE PRETTY MUCH NOTHING. NEXT REAL CHANCE OF PRECIPITATION COMES MAYBE ON THURSDAY NIGHT WITH SOME HINTS OF SHORTWAVE TROUGHING DIGGING INTO THE WESTERN U.S.... RESULTING IN A WARM ADVECTION PATTERN DOWNSTREAM. STILL...THE PRECIPITATION CHANCE LOOKS PRETTY SMALL. THE BIG THING IS TEMPERATURES. 850MB TEMPS ARE PROGGED TO DROP TO ONLY SLOWLY RECOVER TO -6 TO -8C ON WEDNESDAY...THEN FALL BACK TO -12 TO -18C OR SO FOR THURSDAY. THEREFORE...TEMPERATURES ARE FORECAST TO STAY BELOW NORMAL. FOLLOWED A CONSENSUS OF GUIDANCE FOR TEMPERATURES. CANNOT RULE A PERIOD OF SOME BELOW ZERO TEMPERATURES FOR LOWS TOO... ESPECIALLY FOR SOME OF THE TYPICAL COLD SPOTS. && .AVIATION...THROUGH 18Z SATURDAY 1131 AM CST FRI DEC 2 2011 HIGH PRESSURE SLIDES EAST OF THE AREA TONIGHT AS AN AREA OF LOW PRESSURE GETS ORGANIZED ACROSS THE SOUTHERN PLAINS. BIGGEST CONCERN IS ON PRECIPITATION ONSET TIME AND LOWERING CEILINGS AFTER 09Z TONIGHT. VFR CONDITIONS EXPECTED THROUGH 09Z...AFTER WHICH LOW LEVEL MOISTURE GETS PULLED NORTHWARD AHEAD OF THE LOW. CEILINGS WILL LIKELY LOWER AND PRECIPITATION BREAK OUT BETWEEN 09Z-12Z. HOWEVER FEEL CEILINGS WILL REMAIN IN THE VFR CATEGORY UNTIL AT LEAST 12Z. FIRST SURGE OF PRECIPITATION LOOKS TO BE IN THE FORM OF LIGHT SNOW AND HAVE TRENDED TAFS IN THIS DIRECTION WITH MVFR CEILINGS AND VISIBILITIES. WITH WARMER AIR BEING PULLED NORTHWARD...DID MIX WITH SNOW WITH SOME RAIN AT KLSE AFTER 16Z. LATER SHIFTS WILL HAVE TO WATCH FOR LOWER CEILINGS/VISIBILITIES IN THE 10Z-18Z TIME FRAME. && .ARX WATCHES/WARNINGS/ADVISORIES... 347 AM CST FRI DEC 2 2011 WI...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH LATE SATURDAY NIGHT FOR WIZ017-029-032>034. MN...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH LATE SATURDAY NIGHT FOR MNZ079-086>088-094-095. IA...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH LATE SATURDAY NIGHT FOR IAZ008-009-018. && $$ SHORT TERM...AJ LONG TERM....AJ AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
550 AM CST FRI DEC 2 2011 .SHORT TERM...TODAY THROUGH SUNDAY NIGHT 347 AM CST FRI DEC 2 2011 MAIN FORECAST CONCERN IS ON PRECIPITATION FOR AFTER MIDNIGHT TONIGHT THROUGH SUNDAY MORNING AND POSSIBLE HAZARDS. CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A POTENT UPPER TROUGH OVER SOUTHWEST CANADA...RIDGING OUT AHEAD OVER THE NORTHERN PLAINS INTO MANITOBA...AND TROUGHING OVER THE LAKE MICHIGAN AREA. ALSO OF NOTE IS IN THE SOUTHERN STREAM OF AN UPPER LOW OVER THE DESERT SOUTHWEST. THE FORECAST AREA LIES IN SUBSIDENCE IMMEDIATELY BEHIND THE LAKE MICHIGAN TROUGH...PROMOTING HIGH PRESSURE AT THE SURFACE. IN FACT...THE SUBSIDENCE AND DRYING HAS BEEN ENOUGH TO RESULT IN CLEAR SKIES OVER THE AREA. UPSTREAM 00Z SOUNDINGS FROM INL AND ABR REFLECT THE DRYING WELL WITH PRECIPITABLE WATER VALUES UNDER TWO TENTHS OF AN INCH. THE COMBINATION OF THE CLEAR SKIES AND LIGHT WINDS HAS ALLOWED TEMPERATURES TO DROP INTO THE TEENS TO MID 20S. TO THE NORTHWEST...A STREAM OF UPPER LEVEL MOISTURE CAN BE SEEN ACROSS THE NORTHERN PLAINS INTO SOUTH CENTRAL CANADA ON WATER VAPOR....AHEAD OF THE UPPER TROUGH THERE...WHICH IS MANIFESTING ITSELF INTO A LARGE ALTOSTRATUS AND CIRROSTRATUS DECK. TO THE SOUTHWEST...850MB WINDS HAVE BEEN INCREASING OUT OF THE SOUTH OVER TEXAS DOWNSTREAM OF THE UPPER LOW...BRINGING GULF OF MEXICO MOISTURE NORTHWARD TOWARDS OKLAHOMA AS SEEN IN GOES PRECIPITABLE WATER PLOTS. TODAY AND TONIGHT...A WARM ADVECTION PATTERN LOOKS TO DEVELOP OVER THE AREA IN RESPONSE TO THE UPPER TROUGH OVER SOUTHWEST CANADA SPLITTING INTO TWO...WHERE ONE PIECE MARCHES EAST INTO NORTHWEST ONTARIO AND NORTH DAKOTA BY 12Z SATURDAY. THE OTHER PIECE DIGS SOUTH TOWARDS THE LAS VEGAS AREA...CAUSING THE CURRENT UPPER LOW IN ARIZONA TO GET PUSHED EAST INTO NEW MEXICO. CONDITIONS WILL REMAIN DRY TODAY GIVEN PLENTIFUL DRY AIR AROUND AS SEEN FROM 00Z SOUNDINGS. IN FACT...SKIES SHOULD STAY CLEAR TO 00Z. WINDS ARE LIKELY TO INCREASE...THOUGH...AS THE PRESSURE GRADIENT TIGHTENS UP BEHIND THE DEPARTING SURFACE RIDGE. TONIGHT IS A DIFFERENT STORY. THE SOUTHERLY RETURN FLOW SEEN OCCURRING OVER TEXAS NOW IS FORECAST TO EXPAND AND INTENSIFY TONIGHT...RUNNING FROM DEEP SOUTH TEXAS INTO KANSAS...THEN NORTHEAST INTO THE FORECAST AREA BY 06Z. 850MB WINDS IN THIS ZONE ARE PROGGED BETWEEN 40-50 KT. PRECIPITABLE WATER VALUES RESPOND BY JUMPING FROM AROUND 0.25 INCH AT 00Z TO 0.5-0.8 INCHES AT 12Z... HIGHEST IN THE SOUTHEASTERN PORTION OF THE FORECAST AREA. 0.75 INCHES REPRESENTS 200 PERCENT OF NORMAL. AS THE DEEPER MOISTURE ISENTROPICALLY LIFTS INTO THE COLDER AIRMASS OVER THE AREA... ANTICIPATING PRECIPITATION TO BREAK OUT. MODELS ARE IN VERY GOOD AGREEMENT ON THIS OCCURRING...WITH THE HIGHEST CONSENSUS OVER THE SOUTHEASTERN TWO-THIRDS OF THE AREA. PLACED 80-100 PERCENT CHANCES IN THE SOUTHEAST HALF...THEN TRENDED DRIER HEADING UP TO THE NORTHWEST INTO LOWER PRECIPITABLE WATER VALUES. P-TYPE A LITTLE TRICKY AS A SURGE OF WARMER AIR ALSO ACCOMPANIES THE MOISTURE SURGE. 850MB TEMPS ARE PROGGED TO WARM TO 0-2C OVER THE SAME AREA WITH THE HIGHEST PRECIPITABLE WATER. SHOULD BE MOSTLY A RAIN/SNOW SCENARIO AS SURFACE TEMPERATURES WARM OVERNIGHT...BUT COULD SEE FREEZING RAIN TOO IF SURFACE TEMPERATURES HAVE NOT WARMED ABOVE FREEZING OR FROM NOT ENOUGH ICE PRESENT ALOFT YET. ANY SNOW/ICE ACCUMULATION LOOKS MINIMAL TONIGHT. HAVE NOT INCLUDED ANY FREEZING RAIN/DRIZZLE BECAUSE UNCERTAINTY IS JUST TOO HIGH. SATURDAY THROUGH SUNDAY...MODELS ARE ALL IN VERY GOOD AGREEMENT KICKING OUT THE UPPER LOW FROM NEW MEXICO AT 12Z SATURDAY NORTHEAST AS A SHEARING OUT SHORTWAVE. IN ADDITION...THE SHORTWAVE SHOULD GET ACCELERATED NORTHEAST OVERNIGHT TONIGHT INTO SUNDAY IN RESPONSE TO MORE TROUGHING DROPPING SOUTH INTO THE NORTHERN PLAINS. THERE ARE SOME SLIGHT DIFFERENCES WITH RESPECT TO THE ASSOCIATED SURFACE LOW WITH THE SHORTWAVE...WHICH HAS IMPLICATIONS ON THE TRACK AND INTENSITY OF THE DEFORMATION PRECIPITATION ON THE NORTH SIDE OF THE LOW. THE 02.00Z GFS IS THE WEAKEST WITH THE LOW AND FURTHEST SOUTHEAST...HAVING IT TRACK ACROSS NORTHEAST ILLINOIS AT 12Z SUNDAY. THE 02.00Z NAM IS FARTHEST NORTHWEST AND FASTEST...CROSSING THE BAY OF GREEN BAY AT 12Z SUNDAY. THE 02.00Z ECMWF/UKMET IS A COMPROMISE. FOR NOW FOLLOWED THE COMPROMISE APPROACH...SINCE THE GFS SOLUTION IS PLAUSIBLE IF MORE CONVECTION CAN OCCUR THAN CURRENTLY PROGGED DOWN OVER THE SOUTHERN PLAINS. ON THE FLIP SIDE...THERE HAS BEEN QUITE A BIT OF CONSISTENCY WITH THE ECMWF AND NAM SOLUTIONS. SATURDAY MORNING SHOULD BE A CONTINUATION OF PRECIPITATION FROM AFTER MIDNIGHT TONIGHT...DUE TO PERSISTENT ISENTROPIC LIFT. PRECIPITATION THEN LOOKS TO INTENSIFY IN THE AFTERNOON...PARTICULARLY OVER THE NORTHWEST HALF OF THE FORECAST AREA...AS THE DEFORMATION AREA OF THE SURFACE LOW APPROACHES. HEAVIEST PRECIPITATION STILL LOOKS TO OCCUR SATURDAY EVENING WHEN STRONGEST LOW TO MID-LEVEL FRONTOGENESIS MOVES ACROSS. IN FACT...CROSS-SECTIONS SHOW THE PRESENCE OF SOME NEGATIVE EPV ON TOP OF THE FRONTOGENESIS ZONE...SUGGESTING CONVECTIVE ELEMENTS ARE POSSIBLE. AGAIN...THE HEAVIEST PRECIPITATION LOOKS TO END UP OVER THE NORTHWEST HALF OF THE FORECAST AREA. WITH SNOW TO WATER RATIOS LIKELY TO END UP SOMEWHERE AROUND 10 TO 1 AS AN AVERAGE FOR SATURDAY AND SATURDAY NIGHT...COMBINED WITH QPF AMOUNTS AROUND 0.60 OF AN INCH...TOTAL SNOWFALL WOULD COME OUT TO AROUND 6 INCHES. GIVEN THAT THE NORTHWEST HALF OF THE FORECAST AREA HAS NOT REALLY SEEN ITS FIRST SIGNIFICANT SNOW...HAVE ISSUED A WINTER STORM WATCH FOR THAT AREA. BIGGEST CONCERN OF THE WATCH IS SATURDAY AFTERNOON AND EVENING...ESPECIALLY TOO WITH THE HOLIDAY SHOPPING/TRAVEL TAKING PLACE. FOR THE SOUTHEAST END OF THE FORECAST AREA...MAJORITY OF THE PRECIPITATION MAY FALL AS RAIN OR A RAIN/SNOW MIX AS A SURGE OF WARM AIR COMES IN. NEW 02.06Z NAM SUGGESTS EVEN A WARMER SURGE. LA CROSSE COUNTY KEPT OUT OF THE WATCH DUE TO RAIN MIX EXPECTED ON SATURDAY. FOR BOTH SATURDAY AND SATURDAY NIGHT...INCREASED PRECIPITATION CHANCES ANYWHERE FROM 10 TO 30 PERCENT GIVEN GOOD CONTINUITY AND MODEL AGREEMENT. PRECIPITATION SHOULD DIMINISH PRETTY QUICK ON SUNDAY...THOUGH DID KEEP SOME 20 PERCENT CHANCES GOING IN THE AFTERNOON FOR CENTRAL WISCONSIN WITH LINGERING UPPER TROUGHING. CERTAINLY WILL BE COOLER ON SUNDAY WITH SNOW COVER AND 850MB TEMPS OF -6 TO -8C MOVING IN. SUNDAY NIGHT AND MONDAY...ATTENTION TURNS TO THE TROUGHING COMING INTO THE NORTHERN PLAINS ON SUNDAY. GOOD AGREEMENT ON THIS UPPER TROUGH HEADING EAST INTO THE FORECAST AREA ON MONDAY. HOWEVER...ALL OF THE BETTER FORCING/MOISTURE APPEAR TO HEAD TO THE NORTH OF THE AREA. AS SUCH...HAVE CONTINUED A DRY SUNDAY NIGHT AND ONLY KEPT A 20 PERCENT CHANCE IN FOR TAYLOR/CLARK COUNTIES ON MONDAY. COULD SEE CHANCES BEING COMPLETELY REMOVED FOR MONDAY IF TRENDS CONTINUE. ALTHOUGH PRECIPITATION LOOKS LIMITED...THE COLD AIR WILL NOT BE. 850MB TEMPS ARE PROGGED TO FALL EVEN FURTHER...DROPPING TO AT LEAST -8 TO -12C BY 00Z TUESDAY...IF NOT A LITTLE COOLER THAN THAT AS NOTED BY THE 02.00Z GFS. WENT WITH A BLEND OF GUIDANCE FOR LOWS AND HIGHS DURING THIS PERIOD...WHICH END UP 5 TO 10 DEGREES COLDER THAN SATURDAY NIGHT AND SUNDAY. .LONG TERM...MONDAY NIGHT THROUGH THURSDAY NIGHT 347 AM CST FRI DEC 2 2011 AFTER A BUSY EARLY PART TO THE WEEKEND FOR THE WEATHER...MUCH OF THE EARLY AND MIDDLE PORTION OF NEXT WEEK LOOK QUIET AND COOL. 02.00Z ECMWF/CANADIAN/GFS/GFS ENSEMBLES ARE IN GOOD AGREEMENT FOR MUCH OF THE LONG TERM FORECAST INDICATING THE TROUGHING THAT WAS OVER THE AREA MONDAY LINGERING INTO TUESDAY...THEN JUST GRADUAL DEEP TROUGHING FORMING OVER MUCH OF CANADA INTO THE NORTHERN U.S. HEADING INTO THURSDAY. THIS TYPE OF PATTERN SUGGESTS LITTLE MOISTURE TO WORK WITH AND AS SUCH MODEL QPF FORECASTS ARE PRETTY MUCH NOTHING. NEXT REAL CHANCE OF PRECIPITATION COMES MAYBE ON THURSDAY NIGHT WITH SOME HINTS OF SHORTWAVE TROUGHING DIGGING INTO THE WESTERN U.S.... RESULTING IN A WARM ADVECTION PATTERN DOWNSTREAM. STILL...THE PRECIPITATION CHANCE LOOKS PRETTY SMALL. THE BIG THING IS TEMPERATURES. 850MB TEMPS ARE PROGGED TO DROP TO ONLY SLOWLY RECOVER TO -6 TO -8C ON WEDNESDAY...THEN FALL BACK TO -12 TO -18C OR SO FOR THURSDAY. THEREFORE...TEMPERATURES ARE FORECAST TO STAY BELOW NORMAL. FOLLOWED A CONSENSUS OF GUIDANCE FOR TEMPERATURES. CANNOT RULE A PERIOD OF SOME BELOW ZERO TEMPERATURES FOR LOWS TOO... ESPECIALLY FOR SOME OF THE TYPICAL COLD SPOTS. && .AVIATION...TODAY INTO SATURDAY 550 AM CST FRI DEC 2 2011 A RIDGE OF HIGH PRESSURE WILL DRIFT ACROSS ACROSS THE UPPER MIDWEST TODAY INTO THIS EVENING...BRINGING GOOD VFR CONDITIONS TO THE TAF SITES THRU MIDNIGHT TONIGHT. A COLD FRONT WILL BE MOVING ACROSS THE NORTHERN PLAINS TONIGHT WHILE LOW PRESSURE DEVELOPS IN THE SOUTHERN PLAINS. INCREASING LOW/MID LEVEL MOISTURE WILL QUICKLY SURGE NORTH AHEAD OF THE LOW AND FRONT...WITH CIGS EXPECTED TO DEVELOP/LOWER OVER THE TAF SITES LATE TONIGHT. MAIN QUESTION IS HOW QUICKLY WILL CIGS LOWER INTO MVFR AND -SN OR -SN/-RA MOVE INTO THE TAF SITES LATE TONIGHT/SAT MORNING. NO CLEAR MODEL SIGNAL ON THE TIMING. GIVEN THE INITIAL DEEP/DRY AIRMASS OVER THE AREA JUST INTRODUCED VCSH AND LOWERED CIGS INTO THE 3K-4K FT RANGE AT KRST/KLSE TAFS LATE TONIGHT TOWARD THE END OF THE TAF PERIOD. CIGS/VSBYS WILL CONTINUE TO LOWER SAT AS MOISTURE/LIFT CONTINUE TO INCREASE OVER THE AREA AHEAD OF THE APPROACHING LOW...WITH IFR CONDITIONS EXPECTED BY SAT AFTERNOON. AIRMASS WILL BE COLD ENOUGH FOR MAINLY SNOW AT KRST AND A SN/RA MIX AT KLSE. ACCUMULATING SNOWS EXPECTED AT KRST/KLSE...ESPECIALLY BY SAT AFTERNOON AND FOR SAT EVENING. && .ARX WATCHES/WARNINGS/ADVISORIES... 347 AM CST FRI DEC 2 2011 WI...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH LATE SATURDAY NIGHT FOR WIZ017-029-032>034. MN...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH LATE SATURDAY NIGHT FOR MNZ079-086>088-094-095. IA...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH LATE SATURDAY NIGHT FOR IAZ008-009-018. && $$ SHORT TERM...AJ LONG TERM....AJ AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
348 AM CST FRI DEC 2 2011 .SHORT TERM...TODAY THROUGH SUNDAY NIGHT 347 AM CST FRI DEC 2 2011 MAIN FORECAST CONCERN IS ON PRECIPITATION FOR AFTER MIDNIGHT TONIGHT THROUGH SUNDAY MORNING AND POSSIBLE HAZARDS. CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A POTENT UPPER TROUGH OVER SOUTHWEST CANADA...RIDGING OUT AHEAD OVER THE NORTHERN PLAINS INTO MANITOBA...AND TROUGHING OVER THE LAKE MICHIGAN AREA. ALSO OF NOTE IS IN THE SOUTHERN STREAM OF AN UPPER LOW OVER THE DESERT SOUTHWEST. THE FORECAST AREA LIES IN SUBSIDENCE IMMEDIATELY BEHIND THE LAKE MICHIGAN TROUGH...PROMOTING HIGH PRESSURE AT THE SURFACE. IN FACT...THE SUBSIDENCE AND DRYING HAS BEEN ENOUGH TO RESULT IN CLEAR SKIES OVER THE AREA. UPSTREAM 00Z SOUNDINGS FROM INL AND ABR REFLECT THE DRYING WELL WITH PRECIPITABLE WATER VALUES UNDER TWO TENTHS OF AN INCH. THE COMBINATION OF THE CLEAR SKIES AND LIGHT WINDS HAS ALLOWED TEMPERATURES TO DROP INTO THE TEENS TO MID 20S. TO THE NORTHWEST...A STREAM OF UPPER LEVEL MOISTURE CAN BE SEEN ACROSS THE NORTHERN PLAINS INTO SOUTH CENTRAL CANADA ON WATER VAPOR....AHEAD OF THE UPPER TROUGH THERE...WHICH IS MANIFESTING ITSELF INTO A LARGE ALTOSTRATUS AND CIRROSTRATUS DECK. TO THE SOUTHWEST...850MB WINDS HAVE BEEN INCREASING OUT OF THE SOUTH OVER TEXAS DOWNSTREAM OF THE UPPER LOW...BRINGING GULF OF MEXICO MOISTURE NORTHWARD TOWARDS OKLAHOMA AS SEEN IN GOES PRECIPITABLE WATER PLOTS. TODAY AND TONIGHT...A WARM ADVECTION PATTERN LOOKS TO DEVELOP OVER THE AREA IN RESPONSE TO THE UPPER TROUGH OVER SOUTHWEST CANADA SPLITTING INTO TWO...WHERE ONE PIECE MARCHES EAST INTO NORTHWEST ONTARIO AND NORTH DAKOTA BY 12Z SATURDAY. THE OTHER PIECE DIGS SOUTH TOWARDS THE LAS VEGAS AREA...CAUSING THE CURRENT UPPER LOW IN ARIZONA TO GET PUSHED EAST INTO NEW MEXICO. CONDITIONS WILL REMAIN DRY TODAY GIVEN PLENTIFUL DRY AIR AROUND AS SEEN FROM 00Z SOUNDINGS. IN FACT...SKIES SHOULD STAY CLEAR TO 00Z. WINDS ARE LIKELY TO INCREASE...THOUGH...AS THE PRESSURE GRADIENT TIGHTENS UP BEHIND THE DEPARTING SURFACE RIDGE. TONIGHT IS A DIFFERENT STORY. THE SOUTHERLY RETURN FLOW SEEN OCCURRING OVER TEXAS NOW IS FORECAST TO EXPAND AND INTENSIFY TONIGHT...RUNNING FROM DEEP SOUTH TEXAS INTO KANSAS...THEN NORTHEAST INTO THE FORECAST AREA BY 06Z. 850MB WINDS IN THIS ZONE ARE PROGGED BETWEEN 40-50 KT. PRECIPITABLE WATER VALUES RESPOND BY JUMPING FROM AROUND 0.25 INCH AT 00Z TO 0.5-0.8 INCHES AT 12Z... HIGHEST IN THE SOUTHEASTERN PORTION OF THE FORECAST AREA. 0.75 INCHES REPRESENTS 200 PERCENT OF NORMAL. AS THE DEEPER MOISTURE ISENTROPICALLY LIFTS INTO THE COLDER AIRMASS OVER THE AREA... ANTICIPATING PRECIPITATION TO BREAK OUT. MODELS ARE IN VERY GOOD AGREEMENT ON THIS OCCURRING...WITH THE HIGHEST CONSENSUS OVER THE SOUTHEASTERN TWO-THIRDS OF THE AREA. PLACED 80-100 PERCENT CHANCES IN THE SOUTHEAST HALF...THEN TRENDED DRIER HEADING UP TO THE NORTHWEST INTO LOWER PRECIPITABLE WATER VALUES. P-TYPE A LITTLE TRICKY AS A SURGE OF WARMER AIR ALSO ACCOMPANIES THE MOISTURE SURGE. 850MB TEMPS ARE PROGGED TO WARM TO 0-2C OVER THE SAME AREA WITH THE HIGHEST PRECIPITABLE WATER. SHOULD BE MOSTLY A RAIN/SNOW SCENARIO AS SURFACE TEMPERATURES WARM OVERNIGHT...BUT COULD SEE FREEZING RAIN TOO IF SURFACE TEMPERATURES HAVE NOT WARMED ABOVE FREEZING OR FROM NOT ENOUGH ICE PRESENT ALOFT YET. ANY SNOW/ICE ACCUMULATION LOOKS MINIMAL TONIGHT. HAVE NOT INCLUDED ANY FREEZING RAIN/DRIZZLE BECAUSE UNCERTAINTY IS JUST TOO HIGH. SATURDAY THROUGH SUNDAY...MODELS ARE ALL IN VERY GOOD AGREEMENT KICKING OUT THE UPPER LOW FROM NEW MEXICO AT 12Z SATURDAY NORTHEAST AS A SHEARING OUT SHORTWAVE. IN ADDITION...THE SHORTWAVE SHOULD GET ACCELERATED NORTHEAST OVERNIGHT TONIGHT INTO SUNDAY IN RESPONSE TO MORE TROUGHING DROPPING SOUTH INTO THE NORTHERN PLAINS. THERE ARE SOME SLIGHT DIFFERENCES WITH RESPECT TO THE ASSOCIATED SURFACE LOW WITH THE SHORTWAVE...WHICH HAS IMPLICATIONS ON THE TRACK AND INTENSITY OF THE DEFORMATION PRECIPITATION ON THE NORTH SIDE OF THE LOW. THE 02.00Z GFS IS THE WEAKEST WITH THE LOW AND FURTHEST SOUTHEAST...HAVING IT TRACK ACROSS NORTHEAST ILLINOIS AT 12Z SUNDAY. THE 02.00Z NAM IS FARTHEST NORTHWEST AND FASTEST...CROSSING THE BAY OF GREEN BAY AT 12Z SUNDAY. THE 02.00Z ECMWF/UKMET IS A COMPROMISE. FOR NOW FOLLOWED THE COMPROMISE APPROACH...SINCE THE GFS SOLUTION IS PLAUSIBLE IF MORE CONVECTION CAN OCCUR THAN CURRENTLY PROGGED DOWN OVER THE SOUTHERN PLAINS. ON THE FLIP SIDE...THERE HAS BEEN QUITE A BIT OF CONSISTENCY WITH THE ECMWF AND NAM SOLUTIONS. SATURDAY MORNING SHOULD BE A CONTINUATION OF PRECIPITATION FROM AFTER MIDNIGHT TONIGHT...DUE TO PERSISTENT ISENTROPIC LIFT. PRECIPITATION THEN LOOKS TO INTENSIFY IN THE AFTERNOON...PARTICULARLY OVER THE NORTHWEST HALF OF THE FORECAST AREA...AS THE DEFORMATION AREA OF THE SURFACE LOW APPROACHES. HEAVIEST PRECIPITATION STILL LOOKS TO OCCUR SATURDAY EVENING WHEN STRONGEST LOW TO MID-LEVEL FRONTOGENESIS MOVES ACROSS. IN FACT...CROSS-SECTIONS SHOW THE PRESENCE OF SOME NEGATIVE EPV ON TOP OF THE FRONTOGENESIS ZONE...SUGGESTING CONVECTIVE ELEMENTS ARE POSSIBLE. AGAIN...THE HEAVIEST PRECIPITATION LOOKS TO END UP OVER THE NORTHWEST HALF OF THE FORECAST AREA. WITH SNOW TO WATER RATIOS LIKELY TO END UP SOMEWHERE AROUND 10 TO 1 AS AN AVERAGE FOR SATURDAY AND SATURDAY NIGHT...COMBINED WITH QPF AMOUNTS AROUND 0.60 OF AN INCH...TOTAL SNOWFALL WOULD COME OUT TO AROUND 6 INCHES. GIVEN THAT THE NORTHWEST HALF OF THE FORECAST AREA HAS NOT REALLY SEEN ITS FIRST SIGNIFICANT SNOW...HAVE ISSUED A WINTER STORM WATCH FOR THAT AREA. BIGGEST CONCERN OF THE WATCH IS SATURDAY AFTERNOON AND EVENING...ESPECIALLY TOO WITH THE HOLIDAY SHOPPING/TRAVEL TAKING PLACE. FOR THE SOUTHEAST END OF THE FORECAST AREA...MAJORITY OF THE PRECIPITATION MAY FALL AS RAIN OR A RAIN/SNOW MIX AS A SURGE OF WARM AIR COMES IN. NEW 02.06Z NAM SUGGESTS EVEN A WARMER SURGE. LA CROSSE COUNTY KEPT OUT OF THE WATCH DUE TO RAIN MIX EXPECTED ON SATURDAY. FOR BOTH SATURDAY AND SATURDAY NIGHT...INCREASED PRECIPITATION CHANCES ANYWHERE FROM 10 TO 30 PERCENT GIVEN GOOD CONTINUITY AND MODEL AGREEMENT. PRECIPITATION SHOULD DIMINISH PRETTY QUICK ON SUNDAY...THOUGH DID KEEP SOME 20 PERCENT CHANCES GOING IN THE AFTERNOON FOR CENTRAL WISCONSIN WITH LINGERING UPPER TROUGHING. CERTAINLY WILL BE COOLER ON SUNDAY WITH SNOW COVER AND 850MB TEMPS OF -6 TO -8C MOVING IN. SUNDAY NIGHT AND MONDAY...ATTENTION TURNS TO THE TROUGHING COMING INTO THE NORTHERN PLAINS ON SUNDAY. GOOD AGREEMENT ON THIS UPPER TROUGH HEADING EAST INTO THE FORECAST AREA ON MONDAY. HOWEVER...ALL OF THE BETTER FORCING/MOISTURE APPEAR TO HEAD TO THE NORTH OF THE AREA. AS SUCH...HAVE CONTINUED A DRY SUNDAY NIGHT AND ONLY KEPT A 20 PERCENT CHANCE IN FOR TAYLOR/CLARK COUNTIES ON MONDAY. COULD SEE CHANCES BEING COMPLETELY REMOVED FOR MONDAY IF TRENDS CONTINUE. ALTHOUGH PRECIPITATION LOOKS LIMITED...THE COLD AIR WILL NOT BE. 850MB TEMPS ARE PROGGED TO FALL EVEN FURTHER...DROPPING TO AT LEAST -8 TO -12C BY 00Z TUESDAY...IF NOT A LITTLE COOLER THAN THAT AS NOTED BY THE 02.00Z GFS. WENT WITH A BLEND OF GUIDANCE FOR LOWS AND HIGHS DURING THIS PERIOD...WHICH END UP 5 TO 10 DEGREES COLDER THAN SATURDAY NIGHT AND SUNDAY. .LONG TERM...MONDAY NIGHT THROUGH THURSDAY NIGHT 347 AM CST FRI DEC 2 2011 AFTER A BUSY EARLY PART TO THE WEEKEND FOR THE WEATHER...MUCH OF THE EARLY AND MIDDLE PORTION OF NEXT WEEK LOOK QUIET AND COOL. 02.00Z ECMWF/CANADIAN/GFS/GFS ENSEMBLES ARE IN GOOD AGREEMENT FOR MUCH OF THE LONG TERM FORECAST INDICATING THE TROUGHING THAT WAS OVER THE AREA MONDAY LINGERING INTO TUESDAY...THEN JUST GRADUAL DEEP TROUGHING FORMING OVER MUCH OF CANADA INTO THE NORTHERN U.S. HEADING INTO THURSDAY. THIS TYPE OF PATTERN SUGGESTS LITTLE MOISTURE TO WORK WITH AND AS SUCH MODEL QPF FORECASTS ARE PRETTY MUCH NOTHING. NEXT REAL CHANCE OF PRECIPITATION COMES MAYBE ON THURSDAY NIGHT WITH SOME HINTS OF SHORTWAVE TROUGHING DIGGING INTO THE WESTERN U.S.... RESULTING IN A WARM ADVECTION PATTERN DOWNSTREAM. STILL...THE PRECIPITATION CHANCE LOOKS PRETTY SMALL. THE BIG THING IS TEMPERATURES. 850MB TEMPS ARE PROGGED TO DROP TO ONLY SLOWLY RECOVER TO -6 TO -8C ON WEDNESDAY...THEN FALL BACK TO -12 TO -18C OR SO FOR THURSDAY. THEREFORE...TEMPERATURES ARE FORECAST TO STAY BELOW NORMAL. FOLLOWED A CONSENSUS OF GUIDANCE FOR TEMPERATURES. CANNOT RULE A PERIOD OF SOME BELOW ZERO TEMPERATURES FOR LOWS TOO... ESPECIALLY FOR SOME OF THE TYPICAL COLD SPOTS. && .AVIATION... 1110 PM CST THU DEC 1 2011 HIGH PRESSURE WILL CONTINUE TO BUILD ACROSS THE UPPER MISSISSIPPI RIVER VALLEY...BUT QUICKLY SHIFT EAST FRI NIGHT. CLEAR SKIES AND LIGHT WINDS OVERNIGHT...WITH VFR CONDITIONS CONTINUING FOR MUCH OF FRIDAY. LOOK FOR SOME AFTERNOON GUSTINESS THANKS TO SUN AIDED MIXING...MORE SO FOR KRST. CLOUDS WILL START TO RETURN FRI EVENING...THICKENING AND LOWERING OVERNIGHT AS A STORM SYSTEM OVER THE SOUTHERN PLAINS STARTS TO IMPACT THE AREA. MVFR/IFR CEILINGS THEN LOOK LIKELY FOR SAT/SAT NIGHT AS THE SYSTEM PASSES TO THE SOUTH/EAST. RA/SN CAN ALSO BE EXPECTED...WITH SEVERAL INCHES OF SNOW ACCUMULATION AND IMPACTS TO VSBY HEIGHTENED SAT EVENING. CURRENT STORM TRACK WOULD FAVOR KRST FOR MORE SNOW. && .ARX WATCHES/WARNINGS/ADVISORIES... 347 AM CST FRI DEC 2 2011 WI...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH LATE SATURDAY NIGHT FOR WIZ017-029-032>034. MN...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH LATE SATURDAY NIGHT FOR MNZ079-086>088-094-095. IA...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH LATE SATURDAY NIGHT FOR IAZ008-009-018. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION..... RIECK
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1059 PM MST THU DEC 1 2011 .DISCUSSION...THE VISIBILITIES HAVE IMPROVED SOME OVER THE AREA BETWEEN KCYS AND KLAR...INCLUDING THE SOUTHERN LARAMIE RANGE. A SURFACE TROUGH CONTINUES TO DEVELOP OVER FAR EASTERN WYOMING THE REST OF TONIGHT. THE RESULTING INCREASED SURFACE PRESSURE GRADIENT SHOULD INCREASE MIXING AND LIMIT THE POTENTIAL FOR DENSE FOG THE REST OF TONIGHT. FOR THAT REASON...THE DENSE FOG ADVISORY HAS BEEN CANCELLED FOR THE AREA BETWEEN KCYS AND THE SOUTHERN LARAMIE RANGE. && .PREVIOUS DISCUSSION.../ISSUED AT 1015 PM MST THU DEC 1 2011/... .AVIATION...06Z TAFS ONLY PROBLEM AREA THIS EVENING IS GOING TO BE CHEYENNE. LATEST SATELLITE SHOWING AN EXPANDING AREA OF STRATUS ALONG AND EAST OF THE SOUTHERN LARAMIE RANGE. THIS IS BRINGING LIFR CNDITIONS TO KCYS WITH THE EASTERN SLOPES OF THE SOUTHERN LARAMIE RANGE OBSCURED. LATEST HRRR GUIDANCE KEEPS THIS LAYER IN THROUGH 09Z WITH CLEARING AFTERWARDS. DECIDED TO KEEP LIFR/IFR CONDITIONS GOING THROUGH 12Z AS THE AREA IS STILL EXPANDING. NEXT FRONT LOOKS TO DROP INTO SOUTHEAST WYOMING FRIDAY AFTERNOON WITH DECREASING FLIGHT CONDITIONS ONCE AGAIN FRIDAY EVENING INTO SATURDAY. CLAYCOMB && .PREV DISCUSSION... /ISSUED 905 PM MST THU DEC 1 2011/ UPDATE... WYDOT WEBCAMS NOW SHOW DENSE FOG FROM CHEYENNE TO AT LEAST THE INTERSTATE 80 SUMMIT. SEEING REDUCED VISIBILITIES ON INTERSTATE 25 AS WELL OVER WYO HILL. WENT AHEAD WITH A DENSE FOG ADVISORY THROUGH 12Z/5AM. WINDS FORECAST TO BECOME MORE WESTERLY AFTER THAT TIME...WHICH SHOULD DISSIPATE OUT THE FOG. UPDATES HAVE BEEN SENT. PREV DISCUSSION... /ISSUED 827 PM MST THU DEC 1 2011/ UPDATE... STARTING TO SEE FOG DEVELOPING OVER THE LARAMIE SUMMIT ON INTERSTATE 80 BETWEEN CHEYENNE AND LARAMIE. WENT AHEAD AND ISSUED SPS FOR VISIBILITIES DOWN TO A HALF MILE. WILL WAIT ANOTHER FEW MINUTES TO SEE IF IT GETS ANY DENSER. LATEST 11-3.9U SATELLITE IMAGERY SHOWING A FAIRLY CONFINED AREA OF STRATUS OVER THE SUMMIT AT THIS TIME. WILL CONTINUE TO MONITOR TO SEE IF IT EXPANDS ANYMORE BEFORE ISSUING A DENSE FOG ADVISORY. CLAYCOMB && PREV DISCUSSION... /ISSUED 347 PM MST THU DEC 1 2011/ SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT. TONIGHT...SATELLITE IMAGERY...WSR-88D LOOPS...SURFACE OBSERVATIONS INDICATE SNOW HAS NEARLY ENDED ACROSS OUR COUNTIES. BASED ON THE NAM AND GFS SOLUTIONS...WILL LEAVE IN SOME LOW TOKEN POPS FOR THIS EVENING ACROSS THE SIERRA MADRE...SNOWY AND SOUTHERN LARAMIE RANGES. PRIMARY CHALLENGE TONIGHT WILL BE MINIMUM TEMPERATURES AS SKIES CLEAR ALONG WITH FRESH SNOWPACK ALONG WITH LIGHT WINDS. SURFACE LEE TROUGHING WILL DEVELOP LATE TONIGHT IN OUR COUNTIES IN RESPONSE TO NEXT APPROACHING SHORTWAVE TROUGH OVER THE PACIFIC NORTHWEST. HOWEVER...THIS MINIMAL MIXING IS NOT EXPECTED TO HAVE MUCH EFFECT ON LOW TEMPERATURES OVERNIGHT. HAVE UNDERCUT GUIDANCE TEMPERATURES AT MOST LOCATIONS...ESPECIALLY ACROSS THE LARAMIE VALLEY WHERE CLEAR SKIES...FRESH SNOWPACK...LIGHT WINDS AND THE ARCTIC AIRMASS WILL PROMOTE EXCELLENT RADIATIONAL COOLING...PARTICULARLY IN THE HIGH MOUNTAIN VALLEYS AND RIVER VALLEY LOCATIONS. FRIDAY...NEXT SHORTWAVE TROUGH ALOFT FAST ON THE HEELS OF THE CURRENT SHORTWAVE TROUGH. WILL SEE A COLD FRONTAL PASSAGE ACROSS OUR COUNTIES DURING THE DAY...PRECEDED BY A SURFACE TROUGH PASSAGE. EXPECT SNOW SHOWERS IN THE AFTERNOON OVER THE NORTHERN LARAMIE RANGE...SIERRA MADRE RANGE AND SNOWY RANGE DUE TO OROGRAPHICS...DRY ELSEWHERE. FRIDAY NIGHT...SHORTWAVE TROUGH ALOFT PASSES ACROSS OUR COUNTIES WITH THE DEEPER SATURATED LAYER ACROSS OUR WESTERN COUNTIES WEST OF INTERSTATE 25...COINCIDENT WITH THE BEST UPWARD VERTICAL MOTION ASSOCIATED WITH THE SHORTWAVE TROUGH. WILL NEED TO WATCH EXPECTED SNOWFALL AMOUNTS WEST OF A DOUGLAS TO CHEYENNE LINE FOR POSSIBLE WINTER WEATHER ADVISORY CRITERIA. FOR NOW...HAVE INCREASED SNOW CHANCES SIGNIFICANTLY ALONG AND WEST OF THE LARAMIE RANGE WITH NEAR 100 PERCENT POPS ACROSS THE HIGHER PEAKS OF THE NORTHERN LARAMIE... SIERRA MADRE AND SNOWY RANGES...AND LESSER POPS FURTHER EAST AWAY FROM THE GREATEST DYNAMICS. ANOTHER REINFORCING SHOT OF COLD AIR ADVECTS IN FROM THE NORTH. WILL INCLUDE AREAS OF BLOWING SNOW IN AREAS WHERE WINDS AND SNOW LOOK FAVORABLE. SATURDAY...AS OCCURRED TODAY...SNOW GRADUALLY ENDS FROM NORTH TO SOUTH AS THE SHORTWAVE TROUGH ALOFT MOVES ACROSS COLORADO. LOOKS LIKE THE MOTHERLODE OF THE COLD AIRMASS MOVES OVERHEAD IN OUR COUNTIES WITH PROGGED 700 MB TEMPERATURES NEAR -18 CELSIUS... THUS HIGH TEMPERATURES ONLY IN THE TEENS AND 20S...WHICH MAY BE OPTIMISTIC IF CLOUD OPACITY...THICKNESS...IS WELL PRONOUNCED. SATURDAY NIGHT...NEXT SHORTWAVE TROUGH ALOFT...A HEALTHY LOOKING ALBERTA CLIPPER SYSTEM...TRACKS OVER MONTANA AND NORTH DAKOTA... INDUCING SURFACE LOW PRESSURE TO STRENGTHEN ACROSS NORTH DAKOTA AND INCREASING THE PRESSURE GRADIENT ACROSS OUR COUNTIES. BLUSTERY AND COLD NIGHT FOR OUR COUNTIES WITH MINIMUM TEMPERATURES IN THE SINGLE DIGITS BELOW ZERO AND ABOVE ZERO...WITH A FEW LOWER TEENS...AND DECENT DOWNSLOPE WEST WINDS. WIND CHILL TEMPERATURES OF 15 BELOW ZERO TO 30 BELOW ZERO ON TAP ACROSS MUCH OF CARBON AND ALBANY COUNTIES. LONG TERM...SUNDAY THROUGH THURSDAY...UPPER LEVEL TROUGH WILL DIVE SOUTH INTO THE NORTHERN PLAINS FROM CANADA ON SUNDAY. THE ASSOCIATED COLD FRONT WILL MOVE ACROSS THE AREA ON SUNDAY MORNING...THUS EXPECT MAX TEMPS TO OCCUR SOMETIME IN THE MORNING WITH TEMPS THEN FALLING THROUGH THE DAY BEHIND THE FRONT. LIGHT SNOW WILL OCCUR BEHIND THE FRONT WITH NOT MUCH ACCUMULATION EXPECTED OUTSIDE OF THE MOUNTAINS. VERY COLD TEMPS WILL OCCUR SUNDAY NIGHT AS SKIES CLEAR SOMEWHAT AND THE UPPER TROUGH MOVES OVERHEAD...USHERING IN 700MB TEMPS OF -20 TO -25C. MONDAY WILL REMAIN QUITE CHILLY...ALTHOUGH SOME MODERATION IS POSSIBLE WITH MOSTLY CLEAR SKIES. SFC HIGH PRESSURE BEHIND THE FRONT WILL SLIDE SOUTH OF THE AREA ON MONDAY NIGHT WITH THE LEESIDE SFC TROUGH DEEPENING THRU TUESDAY MORNING. WESTERLY WINDS WILL THUS INCREASE AS THIS OCCURS...AND WILL PERSIST THROUGH TUESDAY NIGHT AHEAD OF THE NEXT COLD FRONT AND UPPER LEVEL SYSTEM EXPECTED TO AFFECT THE FORECAST AREA WEDNESDAY AND THURSDAY. SOME LIGHT SNOW IS POSSIBLE WITH THIS SYSTEM ACROSS MUCH OF THE FORECAST AREA. FIRE WEATHER...NO FIRE WEATHER CONCERNS. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...RUBIN LONG TERM/AVIATION...RJM
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1015 PM MST THU DEC 1 2011 .AVIATION...06Z TAFS ONLY PROBLEM AREA THIS EVENING IS GOING TO BE CHEYENNE. LATEST SATELLITE SHOWING AN EXPANDING AREA OF STRATUS ALONG AND EAST OF THE SOUTHERN LARAMIE RANGE. THIS IS BRINGING LIFR CNDITIONS TO KCYS WITH THE EASTERN SLOPES OF THE SOUTHERN LARAMIE RANGE OBSCURED. LATEST HRRR GUIDANCE KEEPS THIS LAYER IN THROUGH 09Z WITH CLEARING AFTERWARDS. DECIDED TO KEEP LIFR/IFR CONDITIONS GOING THROUGH 12Z AS THE AREA IS STILL EXPANDING. NEXT FRONT LOOKS TO DROP INTO SOUTHEAST WYOMING FRIDAY AFTERNOON WITH DECREASING FLIGHT CONDITIONS ONCE AGAIN FRIDAY EVENING INTO SATURDAY. CLAYCOMB && .PREV DISCUSSION... /ISSUED 905 PM MST THU DEC 1 2011/ UPDATE... WYDOT WEBCAMS NOW SHOW DENSE FOG FROM CHEYENNE TO AT LEAST THE INTERSTATE 80 SUMMIT. SEEING REDUCED VISIBILITIES ON INTERSTATE 25 AS WELL OVER WYO HILL. WENT AHEAD WITH A DENSE FOG ADVISORY THROUGH 12Z/5AM. WINDS FORECAST TO BECOME MORE WESTERLY AFTER THAT TIME...WHICH SHOULD DISSIPATE OUT THE FOG. UPDATES HAVE BEEN SENT. PREV DISCUSSION... /ISSUED 827 PM MST THU DEC 1 2011/ UPDATE... STARTING TO SEE FOG DEVELOPING OVER THE LARAMIE SUMMIT ON INTERSTATE 80 BETWEEN CHEYENNE AND LARAMIE. WENT AHEAD AND ISSUED SPS FOR VISIBILITIES DOWN TO A HALF MILE. WILL WAIT ANOTHER FEW MINUTES TO SEE IF IT GETS ANY DENSER. LATEST 11-3.9U SATELLITE IMAGERY SHOWING A FAIRLY CONFINED AREA OF STRATUS OVER THE SUMMIT AT THIS TIME. WILL CONTINUE TO MONITOR TO SEE IF IT EXPANDS ANYMORE BEFORE ISSUING A DENSE FOG ADVISORY. CLAYCOMB && PREV DISCUSSION... /ISSUED 347 PM MST THU DEC 1 2011/ SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT. TONIGHT...SATELLITE IMAGERY...WSR-88D LOOPS...SURFACE OBSERVATIONS INDICATE SNOW HAS NEARLY ENDED ACROSS OUR COUNTIES. BASED ON THE NAM AND GFS SOLUTIONS...WILL LEAVE IN SOME LOW TOKEN POPS FOR THIS EVENING ACROSS THE SIERRA MADRE...SNOWY AND SOUTHERN LARAMIE RANGES. PRIMARY CHALLENGE TONIGHT WILL BE MINIMUM TEMPERATURES AS SKIES CLEAR ALONG WITH FRESH SNOWPACK ALONG WITH LIGHT WINDS. SURFACE LEE TROUGHING WILL DEVELOP LATE TONIGHT IN OUR COUNTIES IN RESPONSE TO NEXT APPROACHING SHORTWAVE TROUGH OVER THE PACIFIC NORTHWEST. HOWEVER...THIS MINIMAL MIXING IS NOT EXPECTED TO HAVE MUCH EFFECT ON LOW TEMPERATURES OVERNIGHT. HAVE UNDERCUT GUIDANCE TEMPERATURES AT MOST LOCATIONS...ESPECIALLY ACROSS THE LARAMIE VALLEY WHERE CLEAR SKIES...FRESH SNOWPACK...LIGHT WINDS AND THE ARCTIC AIRMASS WILL PROMOTE EXCELLENT RADIATIONAL COOLING...PARTICULARLY IN THE HIGH MOUNTAIN VALLEYS AND RIVER VALLEY LOCATIONS. FRIDAY...NEXT SHORTWAVE TROUGH ALOFT FAST ON THE HEELS OF THE CURRENT SHORTWAVE TROUGH. WILL SEE A COLD FRONTAL PASSAGE ACROSS OUR COUNTIES DURING THE DAY...PRECEDED BY A SURFACE TROUGH PASSAGE. EXPECT SNOW SHOWERS IN THE AFTERNOON OVER THE NORTHERN LARAMIE RANGE...SIERRA MADRE RANGE AND SNOWY RANGE DUE TO OROGRAPHICS...DRY ELSEWHERE. FRIDAY NIGHT...SHORTWAVE TROUGH ALOFT PASSES ACROSS OUR COUNTIES WITH THE DEEPER SATURATED LAYER ACROSS OUR WESTERN COUNTIES WEST OF INTERSTATE 25...COINCIDENT WITH THE BEST UPWARD VERTICAL MOTION ASSOCIATED WITH THE SHORTWAVE TROUGH. WILL NEED TO WATCH EXPECTED SNOWFALL AMOUNTS WEST OF A DOUGLAS TO CHEYENNE LINE FOR POSSIBLE WINTER WEATHER ADVISORY CRITERIA. FOR NOW...HAVE INCREASED SNOW CHANCES SIGNIFICANTLY ALONG AND WEST OF THE LARAMIE RANGE WITH NEAR 100 PERCENT POPS ACROSS THE HIGHER PEAKS OF THE NORTHERN LARAMIE... SIERRA MADRE AND SNOWY RANGES...AND LESSER POPS FURTHER EAST AWAY FROM THE GREATEST DYNAMICS. ANOTHER REINFORCING SHOT OF COLD AIR ADVECTS IN FROM THE NORTH. WILL INCLUDE AREAS OF BLOWING SNOW IN AREAS WHERE WINDS AND SNOW LOOK FAVORABLE. SATURDAY...AS OCCURRED TODAY...SNOW GRADUALLY ENDS FROM NORTH TO SOUTH AS THE SHORTWAVE TROUGH ALOFT MOVES ACROSS COLORADO. LOOKS LIKE THE MOTHERLODE OF THE COLD AIRMASS MOVES OVERHEAD IN OUR COUNTIES WITH PROGGED 700 MB TEMPERATURES NEAR -18 CELSIUS... THUS HIGH TEMPERATURES ONLY IN THE TEENS AND 20S...WHICH MAY BE OPTIMISTIC IF CLOUD OPACITY...THICKNESS...IS WELL PRONOUNCED. SATURDAY NIGHT...NEXT SHORTWAVE TROUGH ALOFT...A HEALTHY LOOKING ALBERTA CLIPPER SYSTEM...TRACKS OVER MONTANA AND NORTH DAKOTA... INDUCING SURFACE LOW PRESSURE TO STRENGTHEN ACROSS NORTH DAKOTA AND INCREASING THE PRESSURE GRADIENT ACROSS OUR COUNTIES. BLUSTERY AND COLD NIGHT FOR OUR COUNTIES WITH MINIMUM TEMPERATURES IN THE SINGLE DIGITS BELOW ZERO AND ABOVE ZERO...WITH A FEW LOWER TEENS...AND DECENT DOWNSLOPE WEST WINDS. WIND CHILL TEMPERATURES OF 15 BELOW ZERO TO 30 BELOW ZERO ON TAP ACROSS MUCH OF CARBON AND ALBANY COUNTIES. LONG TERM...SUNDAY THROUGH THURSDAY...UPPER LEVEL TROUGH WILL DIVE SOUTH INTO THE NORTHERN PLAINS FROM CANADA ON SUNDAY. THE ASSOCIATED COLD FRONT WILL MOVE ACROSS THE AREA ON SUNDAY MORNING...THUS EXPECT MAX TEMPS TO OCCUR SOMETIME IN THE MORNING WITH TEMPS THEN FALLING THROUGH THE DAY BEHIND THE FRONT. LIGHT SNOW WILL OCCUR BEHIND THE FRONT WITH NOT MUCH ACCUMULATION EXPECTED OUTSIDE OF THE MOUNTAINS. VERY COLD TEMPS WILL OCCUR SUNDAY NIGHT AS SKIES CLEAR SOMEWHAT AND THE UPPER TROUGH MOVES OVERHEAD...USHERING IN 700MB TEMPS OF -20 TO -25C. MONDAY WILL REMAIN QUITE CHILLY...ALTHOUGH SOME MODERATION IS POSSIBLE WITH MOSTLY CLEAR SKIES. SFC HIGH PRESSURE BEHIND THE FRONT WILL SLIDE SOUTH OF THE AREA ON MONDAY NIGHT WITH THE LEESIDE SFC TROUGH DEEPENING THRU TUESDAY MORNING. WESTERLY WINDS WILL THUS INCREASE AS THIS OCCURS...AND WILL PERSIST THROUGH TUESDAY NIGHT AHEAD OF THE NEXT COLD FRONT AND UPPER LEVEL SYSTEM EXPECTED TO AFFECT THE FORECAST AREA WEDNESDAY AND THURSDAY. SOME LIGHT SNOW IS POSSIBLE WITH THIS SYSTEM ACROSS MUCH OF THE FORECAST AREA. FIRE WEATHER...NO FIRE WEATHER CONCERNS. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...DENSE FOG ADVISORY UNTIL 5 AM FRIDAY FOR WYZ116-WYZ117-WYZ118. NE...NONE. && $$ SHORT TERM...RUBIN LONG TERM/AVIATION...RJM
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
310 AM EST SUN DEC 4 2011 .SYNOPSIS... HIGH PRESSURE WILL REMAIN CENTERED NORTH OF THE REGION THROUGH EARLY THIS WEEK AS A WEAK TROUGH OF LOW PRESSURE LINGERS OFFSHORE. A COLD FRONT WILL IMPACT THE AREA DURING MID WEEK FOLLOWED BY HIGH PRESSURE FOR LATE IN THE WEEK. && .NEAR TERM /THROUGH TODAY/... IT IS CONSIDERABLY WARMER ACROSS SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA EARLY THIS MORNING WITH 24 HOUR TEMPERATURE CHANGES AVERAGING BETWEEN +15 AND +20 DEGREES PER 04/07Z REGIONAL OBSERVATIONS. THIS TREND WILL CONTINUE THROUGH SUNRISE WITH LITTLE CHANGE IN TEMPERATURES EXPECTED. DEEP LAYERED HIGH PRESSURE WILL HOLD FIRM ACROSS THE CAROLINAS AND EASTERN GEORGIA TODAY AS AN IMPRESSIVE UPPER LEVEL TROUGH DOMINATES MUCH OF THE WESTERN AND CENTRAL PORTIONS OF THE COUNTRY. CLOUD COVER IS EXPECTED TO THICKEN THROUGH THE DAY AS 290-295K ISENTROPIC LIFT PERSISTS ATOP THE LOW-LEVEL SURFACE WEDGE. ALTHOUGH THE LOWEST 4000 FT OF THE COLUMN WILL BE QUITE MOIST... THE REMAINDER OF THE LOWER TROPOSPHERE WILL REMAIN TOO DRY TO SUPPORT MUCH IN THE WAY OF SIGNIFICANT RAINFALL. ALTHOUGH A FEW SPRINKLES COULD OCCUR AT VARIOUS LOCATIONS THROUGH THE DAY... ESPECIALLY AT THE COAST CLOSER TO THE COASTAL TROUGH...THE PROSPECTS FOR MEASURABLE RAINFALL ARE TOO LOW TO JUSTIFY ANY MENTION OF RAIN CHANCES THROUGH SUNSET. HIGH TEMPERATURES WILL BE TEMPERED BY A STRENGTHENING ONSHORE FLOW AND INCREASED CLOUD COVER. MODEL SOUNDINGS SUGGEST A SLIGHT LOWERING OF OUR HIGH TEMPERATURE FORECAST IS NEEDED FOR MOST LOCATIONS...BUT ONLY BY 1-2 DEGREES. STILL EXPECT AT OR SLIGHTLY ABOVE NORMAL TEMPERATURES FOR EARLY DECEMBER WITH HIGHS GENERALLY TOPPING OUT IN THE MID-UPPER 60S. IT SHOULD BE NOTED THAT SOME GRIDDED GUIDANCE SUGGESTS TEMPERATURES MAY BE CONFINED TO THE LOWER-MID 60S. WILL HAVE TO SEE HOW IF THESE TRENDS CONTINUE AND IF THEY DO A SLIGHTLY LOWERING MAY BE CONSIDERED LATER TODAY. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY/... THE UPPER RIDGE WILL BEGIN TO RAPIDLY ERODE TONIGHT AS THE UPPER TROUGH TO THE WEST DRAWS CLOSER. THE LOW-LEVEL LOOKS TO HOLD FIRM WITH THE COASTAL TROUGH LURKING JUST OFFSHORE FOR MUCH OF THE NIGHT. CONTINUED ISENTROPIC LIFT WILL HELP MAINTAIN QUITE A BIT OF CLOUD COVER OVERNIGHT WITH AN OUTSIDE CHANCE FOR A BRIEF SPRINKLE OR LIGHT SHOWER POTENTIALLY MOVING ONSHORE AT THE COAST. WE CONTINUE TO FAVOR A DRY FORECAST WITH GRIDDED POPS GENERALLY RANGING BETWEEN 5-10 PERCENT. SIMILAR TO THIS MORNING...THE INCREASED CLOUD COVER AND A BIT MORE WIND WILL YIELD A RELATIVELY WARM NIGHT WITH LOWS RANGING FROM THE LOWER 50S INLAND TO THE UPPER 50S/NEAR 60 AT THE COAST. THERE IS SOME CONCERN FOR FOG TO DEVELOP AFTER MIDNIGHT AS STRATUS TRIES TO BUILD DOWN...BUT CONFIDENCE THIS FAR OUT IS NOT HIGH ENOUGH TO JUSTIFY A MENTION ATTM. AT MID LEVELS...A STRONG RIDGE WILL DOMINATE THE SOUTHEAST MONDAY AND TUESDAY...WHILE SURFACE HIGH PRESSURE SLOWLY RETREATS INTO THE ATLANTIC. TEMPERATURES WILL BE ABOVE NORMAL THE FIRST HALF OF THE WEEK...EXCEPT ALONG THE IMMEDIATE COAST WHERE SURFACE WINDS WILL GENERALLY BE FROM THE SOUTHEAST DURING THIS PERIOD. THERE IS A CHANCE OF A FEW SHOWERS AROUND BY TUESDAY AS A COLD FRONT MAKES SLOW PROGRESS INTO NORTHERN GEORGIA AND UPSTATE SOUTH CAROLINA...BUT MOST OF THE ACTIVITY SHOULD REMAIN TO THE NORTHWEST OF THE AREA. THE FORECAST BECOMES MUCH MORE DIFFICULT FOR WEDNESDAY. THE MAIN QUESTION WILL BE THE SPEED OF THE FRONT APPROACHING FROM THE WEST. THE 00Z GFS ESSENTIALLY STALLS THE FRONT FROM UPSTATE SOUTH CAROLINA TO CENTRAL GEORGIA...KEEPING THE FORECAST AREA ON THE WARM SIDE OF THE SYSTEM. HOWEVER...BOTH THE CMC AND ECMWF ARE A LITTLE MORE PROGRESSIVE AND HAVE THE FRONT MOVING SLOWLY THROUGH THE CWA LATER WEDNESDAY. THE DIFFERENCES IN FRONTAL TIMING ARE MAINLY MODULATED BY THE EXPECTED DEVELOPMENT OF A SURFACE LOW PRESSURE AREA ALONG THE FRONT. THE GFS IS FURTHEST WEST WITH THE DEVELOPMENT...AND ACTUALLY BRINGS A LOW OUT OF THE EASTERN GULF OF MEXICO INTO GEORGIA THURSDAY MORNING AND DOES NOT DRAG THE FRONT THROUGH THE CWA UNTIL THURSDAY. RIGHT NOW THIS IS AN OUTLIER...AND NOT ONLY DO THE OTHER GLOBAL MODELS BRING THE FRONT THROUGH FASTER...THERE ARE SEVERAL MEMBERS OF THE GFS ENSEMBLE WHICH ARE ALSO FASTER. THEREFORE...I HAVE GONE MORE WITH A MIDDLE OF THE ROAD SOLUTION...KEEPING MOST OF THE AREA ON THE WARM SIDE WEDNESDAY...BUT WITH THE FRONT KNOCKING ON THE DOOR BY AFTERNOON. I HAVE CONTINUED CHANCE POPS ON WEDNESDAY ACROSS THE AREA...BUT FRONTAL TIMING MAY CAUSE AN INCREASE OR DECREASE OF THESE VALUES WITH TIME. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... BASED ON THE THINKING MENTIONED ABOVE...I AM GOING FOR A SCENARIO WITH A FRONTAL PASSAGE WEDNESDAY NIGHT ACROSS THE CWA FROM WEST TO EAST. THIS IS NOT MUCH DIFFERENT THAN THE PREVIOUS FORECAST WAS SHOWING...ALTHOUGH I DID HAVE TO MAKE SOME APPROPRIATE ADJUSTMENTS TO THE TEMPS AND DEW POINTS TO ACCOUNT FOR THE SPEED OF THE FRONT. FOR PRECIP...DUE TO THE UNCERTAINTY IN THE TIMING I AM JUST GOING WITH CHANCE POPS WEDNESDAY NIGHT. THOSE MIGHT HAVE TO BE RAISED IN A DAY OR TWO WHEN THE TIMING IS A BIT MORE CERTAIN. COOLER AND DRIER WEATHER WILL MOVE IN BEHIND THE FRONT FOR THE END OF THE WEEK. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... EXTREMELY TRICKY AVIATION FORECAST FOR THE NEXT 24 HOURS. OF MOST IMPORTANCE IS THE NEXT 6-9 HOURS WHERE THE GREATEST AVIATION IMPACTS CAN BE EXPECTED. SATELLITE SHOWS LOW/MID-LEVEL CLOUD DECKS RAPIDLY EXPANDING ACROSS THE REGION COINCIDENT WITH INCREASING ISENTROPIC ASSENT. EXPECT MVFR CIGS TO OVERSPREAD KCHS/KSAV WITHIN THE NEXT FEW HOURS WITH BOTH RUC AND NAM SOUNDINGS INDICATING A POTENTIAL FOR IFR CIGS AFTER 09Z...IF NOT SOONER. GIVEN CURRENT CIG TRENDS SOUTH OF THE ALTAMAHA RIVER...WE SUSPECT KSAV HAS THE HIGHEST CHANCE FOR SEEING IFR CONDITIONS OVER THE NEXT FEW HOURS SO WILL INTRODUCE A TEMPO GROUP FROM 09-12Z TO TAKE THIS INTO ACCOUNT. CONFIDENCE IS NOT AS HIGH AT KCHS SO WILL ONLY UTILIZE A TEMPO 09-12Z FOR LOW-END MVFR CIGS AT THIS POINT. SHOULD TRENDS SUGGEST IFR CONDITIONS WILL DEVELOP AND AMENDMENT WILL BE ISSUED. LOW CONFIDENCE ON EXACTLY WHEN CIGS WILL RISE BACK TO VFR LEVELS WITH GUIDANCE ESSENTIALLY SPLIT. SOME KEEP CIGS IN MVFR TERRITORY FOR MUCH OF THE 06Z TAF PERIOD WHILE OTHERS BRING CONDITIONS BACK TO VFR BY LATE MORNING/EARLY AFTERNOON. WILL TAKE THE MORE CONSERVATIVE ROUTE AT THIS POINT GIVEN ALL OF THE UNCERTAINTIES AND SHOW VFR CIGS RETURNING TO BOTH TERMINALS BY 15-16Z. EXTENDED AVIATION OUTLOOK...CAN NOT RULE OUT MVFR CIGS ON OCCASION AT THE TERMINALS MONDAY AND TUESDAY MORNINGS WITH THE ONSHORE FLOW POTENTIALLY BRINGING IN A MARINE STRATUS DECK...BUT THE BEST CHANCE OF REDUCED CIGS/VSBYS WILL BE LATER WEDNESDAY INTO THURSDAY MORNING WITH THE COLD FRONT PASSAGE. && .MARINE... WINDS AND SEAS CONTINUE TO BUILD ACROSS THE WATERS EARLY THIS MORNING. THE COASTAL THROUGH RECENTLY PUSHED WEST OF BUOY 41004 SO EXPECT WINDS TO GRADUALLY DIMINISH SOUTH OF EDISTO BEACH OVER THE NEXT FEW HOURS. A PINCHED GRADIENT WILL LIKELY CONTINUE OVER THE CHARLESTON COUNTY COASTAL WATERS WHERE WINDS OF 15-20 KT WITH HIGHER GUSTS WILL LIKELY PERSIST THROUGH AT LEAST LATE MORNING. BUOY AND WW4 OUTPUT SUGGEST SEAS RANGE FROM 4-6 NEARSHORE AND 6-8 FT OFFSHORE. THE SMALL CRAFT ADVISORY LOOKS WELL PLACED FOR ALL BUT THE CHARLESTON HARBOR. THE PRESSURE GRADIENT IS EXPECTED TO RE-TIGHTEN THIS EVENING AS INLAND AREAS COOL AND THE COASTAL THROUGH MEANDERS EVEN CLOSER TO THE BEACHES. THE MOST ENHANCED GRADIENT LOOKS TO OCCUR OVER THE FAVORED CHARLESTON COUNTY COASTAL WATERS WHERE SPEEDS COULD REACH AS HIGH AS 15-20 KT. THE FAVORED NORTHEAST FETCH WILL KEEP SEAS ELEVATED...BUT THE LATEST WW4 OUTPUT KEEPS SEAS BELOW 6 FT OVER THE NEARSHORE WATERS. SEAS LOOK TO REMAIN ABOVE 6 FT OVER THE GEORGIA OFFSHORE LEG THROUGH THE NIGHT. WINDS SHOULD BE GENERALLY 15 KNOTS OR LESS OUT OF THE EAST AND SOUTHEAST MONDAY AND TUESDAY WITH HIGH PRESSURE IN THE WESTERN ATLANTIC SLOW TO MOVE EASTWARD. WINDS WILL PICK UP WEDNESDAY AHEAD OF THE APPROACHING COLD FRONT...THEN STAY UP BEHIND THE FRONT ON THURSDAY...WITH WINDS VEERING TO WEST AND NORTHWEST. SCAS ARE EXPECTED AT SOME POINT MID WEEK. SEAS WILL BE A BIT MORE OF A PROBLEM DUE TO THE EXTENDED FETCH FROM THE EAST. HEIGHTS OF 6 FEET OR MORE ARE EXPECTED IN THE OUTER GEORGIA WATERS FOR A FEW DAYS NEXT WEEK...WHILE SEAS WILL BE COMING UP IN THE NEARSHORE WATERS BUT MAY NOT REACH THE SCA CRITERIA OF 6 FEET. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR AMZ350- 352-354. SMALL CRAFT ADVISORY UNTIL 5 PM EST THURSDAY FOR AMZ374. && $$
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1231 AM EST SUN DEC 4 2011 .SYNOPSIS... HIGH PRESSURE WILL REMAIN CENTERED NORTH OF THE REGION THROUGH EARLY NEXT WEEK...WHILE A WEAK TROUGH OF LOW PRESSURE WILL DEVELOP AND PERSIST ACROSS THE NEARBY COASTAL WATERS DURING THIS TIME. A COLD FRONT WILL IMPACT THE AREA DURING MID WEEK...FOLLOWED BY HIGH PRESSURE FOR LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... SATELLITE SHOWS LOW/MID-LEVEL CLOUDS RAPIDLY EXPANDING. SHOULD SEE MOST AREAS GO MOSTLY CLOUDY IF NOT CLOUDY OVER THE NEXT FEW HOURS. WILL NEED TO MAKE SOME ADJUSTMENT TO TEMPERATURES WITH THE EARLY MORNING UPDATE. && .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/... MODELS ARE GENERALLY IN GOOD AGREEMENT...SHOWING A DEEP LAYERED RIDGE EXTENDING FROM THE EASTERN GULF OF MEXICO TO NOVA SCOTIA AND A BROAD POSITIVELY TILTED TROUGH FROM THE NORTHERN PLAINS INTO THE FOUR CORNERS REGION ON SUNDAY. THIS SYNOPTIC PATTERN WILL GRADUALLY SHIFT EASTWARD THROUGH THE SHORT TERM PERIOD. SUNDAY...SURFACE HIGH PRESSURE WILL CONTINUE TO WEDGE INTO THE REGION FROM THE NORTH. SKIES SHOULD BE PARTLY TO MOSTLY CLOUDY FOR THE MAJORITY OF THE DAY WITH AMPLE MOISTURE TRAPPED BENEATH A MID LEVEL INVERSION ACCORDING TO MODEL SOUNDINGS. THESE CLOUDS WILL LIKELY STICK AROUND THROUGH SUNDAY NIGHT AS THE LOW LEVEL FLOW REMAINS ONSHORE. DAYTIME TEMPERATURES MIGHT BE HELD DOWN A BIT DUE TO THE CLOUD COVER...BUT STILL EXPECT HIGHS TO REACH THE UPPER 60S. TEMPERATURES SUNDAY NIGHT WILL ONLY FALL INTO THE UPPER 40S OR LOWER 50S GIVEN THE CLOUD COVER AS WELL. MONDAY...THE SURFACE RIDGE WILL SHIFT OFFSHORE ALLOWING THE LOW LEVEL FLOW TO VEER SOUTHEASTERLY. WHILE LOW LEVEL MOISTURE WILL CONTINUE TO ADVECT INTO THE AREA MAINTAINING PARTLY TO PERHAPS MOSTLY CLOUDY SKIES...THE MOISTURE SHOULD BE TOO SHALLOW AND SUBSIDENCE TOO STRONG TO SUPPORT ANY PRECIPITATION. HIGHS WILL REMAIN IN THE UPPER 60S WITH LOWS MONDAY NIGHT EVEN MILDER IN THE MID 50S. TUESDAY...THERE IS NOW BETTER MODEL AGREEMENT INDICATING THAT THE UPPER LEVEL PATTERN WILL BE LESS PROGRESSIVE...DELAYING THE APPROACH OF A COLD FRONT FROM THE WEST. HAVE LOWERED THE POTENTIAL FOR PRECIPITATION AS A RESULT...ONLY SHOWING A SLIGHT CHANCE OF SHOWERS FOR INLAND AREAS. TEMPERATURES AHEAD OF THE FRONT SHOULD WARM WELL INTO THE 70S. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... HE PATTERN FOR THIS PERIOD CONTINUES TO BE SOMEWHAT UNCERTAIN... ALTHOUGH THE LATEST TRENDS SUGGEST A DELAYED PROGRESSION OF THE SYNOPTIC FLOW. MODELS ARE STRUGGLING WITH HOW TO HANDLE THE EVOLUTION OF THE LARGE UPPER LEVEL TROUGH OVER THE WEST. THE GENERAL CONSENSUS SEEMS TO BE POINTING TOWARD EJECTING THE TROUGH ENE ON WEDNESDAY...PUSHING THE FRONT THROUGH SOMETIME WEDNESDAY NIGHT. THE FORECAST WILL SHOW A CHANCE OF SHOWERS THROUGH WEDNESDAY NIGHT...WITH DRYING THEN OCCURRING BEHIND THE FRONT AS HIGH PRESSURE BUILDS IN FOR LATE IN THE WEEK. THE AIRMASS AHEAD OF THE FRONT WILL REMAIN UNSEASONABLY WARM...WITH COOLER CONDITIONS IN ITS WAKE. THE GFS IS INDICATING THAT THE UPPER FLOW WILL BE QUITE PROGRESSIVE...WITH ANOTHER DEEP UPPER TROUGH DEVELOPING OVER THE WESTERN U.S. BY FRIDAY...THEN PUSHING ANOTHER COLD FRONT THROUGH THE REGION FRIDAY NIGHT/EARLY SATURDAY. CONFIDENCE IN THIS SOLUTION IS RATHER LOW GIVEN THE UNCERTAINTY BEFORE THIS PERIOD. HAVE GONE WITH SLIGHTLY COOLER THAN NORMAL TEMPS FRIDAY NIGHT AND SATURDAY FOR NOW. THE GFS WAS NOT SHOWING MUCH MOISTURE ASSOCIATED WITH THIS FRONT. THUS HAVE KEPT POPS BELOW 15 PERCENT. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... EXTREMELY TRICKY AVIATION FORECAST FOR THE NEXT 24 HOURS. OF MOST IMPORTANCE IS THE NEXT 6-9 HOURS WHERE THE GREATEST AVIATION IMPACTS CAN BE EXPECTED. SATELLITE SHOWS LOW/MID-LEVEL CLOUD DECKS RAPIDLY EXPANDING ACROSS THE REGION COINCIDENT WITH INCREASING ISENTROPIC ASSENT. EXPECT MVFR CIGS TO OVERSPREAD KCHS/KSAV WITHIN THE NEXT FEW HOURS WITH BOTH RUC AND NAM SOUNDINGS INDICATING A POTENTIAL FOR IFR CIGS AFTER 09Z...IF NOT SOONER. GIVEN CURRENT CIG TRENDS SOUTH OF THE ALTAMAHA RIVER...WE SUSPECT KSAV HAS THE HIGHEST CHANCE FOR SEEING IFR CONDITIONS OVER THE NEXT FEW HOURS SO WILL INTRODUCE A TEMPO GROUP FROM 09-12Z TO TAKE THIS INTO ACCOUNT. CONFIDENCE IS NOT AS HIGH AT KCHS SO WILL ONLY UTILIZE A TEMPO 09-12Z FOR LOW-END MVFR CIGS AT THIS POINT. SHOULD TRENDS SUGGEST IFR CONDITIONS WILL DEVELOP AND AMENDMENT WILL BE ISSUED. LOW CONFIDENCE ON EXACTLY WHEN CIGS WILL RISE BACK TO VFR LEVELS WITH GUIDANCE ESSENTIALLY SPLIT. SOME KEEP CIGS IN MVFR TERRITORY FOR MUCH OF THE 06Z TAF PERIOD WHILE OTHERS BRING CONDITIONS BACK TO VFR BY LATE MORNING/EARLY AFTERNOON. WILL TAKE THE MORE CONSERVATIVE ROUTE AT THIS POINT GIVEN ALL OF THE UNCERTAINTIES AND SHOW VFR CIGS RETURNING TO BOTH TERMINALS BY 15-16Z. EXTENDED AVIATION OUTLOOK...THERE IS A POTENTIAL FOR PERIODIC MVFR CIGS SUNDAY NIGHT INTO TUESDAY IN ASSOCIATION WITH A COASTAL TROUGH AND INCREASING LOW LEVEL MOISTURE. MVFR OR LOWER VSBYS ARE ALSO POSSIBLE IN FOG DURING THE LATE NIGHT/EARLY MORNING HOURS THROUGH THE FIRST PART OF THE WEEK. THERE COULD BE SOME BRIEF PERIODS OF MVFR CIGS AGAIN WITH SCATTERED SHOWERS ASSOCIATED WITH THE NEXT FRONT WEDNESDAY AND WEDNESDAY NIGHT. && .MARINE... BUOY OBSERVATIONS AND WW4 OUTPUT SUGGESTS SEAS HAVE BREACHED 6 FT ACROSS THE SOUTH CAROLINA MARINE ZONES. HAVE EXPANDED THE SMALL CRAFT ADVISORY TO THESE ZONES. A TIGHT SURFACE PRESSURE GRADIENT WILL CONTINUE TO SUPPORT NE WINDS 15-20 KT INTO THE OVERNIGHT...WITH GUSTS TO 25 KT ACROSS GA WATERS. PER THE LATEST OPC DEPICTION OF THE WAVE HEIGHT GRADIENT... CAPPED SEAS AT 5 FT WITH NO SCA/S ACROSS SC NEARSHORE WATERS...BUT 6 FT SEAS WILL IMPACT AREAS AT OR JUST BEYOND THE 20 NM BENCHMARK. LATER TONIGHT...NAM GUIDANCE CONTINUES TO DEPICT WEAK TROUGH DEVELOPMENT ACCOMPANIED BY GRADUAL RELAXATION OF THE PRESSURE GRADIENT. CONFIDENCE IN THIS SCENARIO REMAINS LESS THAN IDEAL...BUT FORECASTS CONTINUE TO DEPICT DECREASING WINDS LATER TONIGHT. HIGH PRESSURE TO THE NORTHEAST OF THE REGION WILL CONTINUE TO PRODUCE LONG FETCH NE FLOW THROUGH SUNDAY. WINDS WILL VEER TO SE FOR MONDAY THEN MORE SOUTHERLY BY TUESDAY AS A COLD FRONT GRADUALLY APPROACHES FROM THE WEST. THERE IS STILL SOME UNCERTAINTY WITH RESPECT TO THE TIMING/STRENGTH OF THE FRONT...BUT MODEL CONSENSUS SHOWS IT PUSHING OFFSHORE WEDNESDAY NIGHT. WINDS AHEAD AND IMMEDIATELY IN WAKE OF THE FRONT COULD APPROACH SMALL CRAFT ADVISORY LEVELS. MEANWHILE...MARGINAL SMALL CRAFT ADVISORY CONDITIONS DUE TO SEAS IN THE OUTER GEORGIA WATERS SHOULD CONTINUE THROUGH MID WEEK. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR AMZ350- 352-354. SMALL CRAFT ADVISORY UNTIL NOON EST THURSDAY FOR AMZ374. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
341 AM CST SUN DEC 4 2011 .DISCUSSION... 340 AM CST HIGHLIGHTS THIS WEEK WILL INCLUDE RAIN COMING TO AN END...POSSIBLE SN/RASN/RA ACROSS THE SOUTHEAST MONDAY...LES POTENTIAL FOR LAKE/COOK LATE SUNDAY NIGHT INTO MONDAY...TRANSITIONING SOUTH TO LAKE/PORTER INDIANA BY TUESDAY...A FEW DAYS OF QUIET...FOLLOWED BY A LATE CLIPPER AND SNOW POTENTIAL AND FINALLY A BLAST OF COLD BY NEXT WEEKEND. THE EARLY MORNING SURFACE MAP SHOWED THE SURFACE LOW THAT HAS BEEN BRINGING THE WET AND ACTIVE WEATHER TO THE AREA TODAY...CONTINUING TO LIFTING NORTH THROUGH CENTRAL WISCONSIN. MEANWHILE AN ATTENDANT COLD FRONT LAY ROUGHLY ACROSS THE MISSISSIPPI RIVER...SOUTHWEST NEARLY TO ST LOUIS. THIS FRONT WILL CONTINUE TO SLOWLY SWEEP FROM WEST TO EAST THIS MORNING EVENTUALLY PUSHING ITSELF AND THE PRECIP EAST. THE MOST WIDE SPREAD ECHOES HAVE PUSHED EAST AND ONLY A FEW SCATTERED SHOWERS ARE LOCATED WITH THE ACTUAL FRONT. ACROSS EAST CENTRAL IOWA...TEMPERATURES HAVE DROPPED ENOUGH THAT -SN WAS REPORTED...BUT CLOUD TOPS HAVE WARMED ENOUGH AND ARE WARMER THAN -10C. THIS MEANS THAT THERE IS NO LONGER ICE INTRODUCTION INTO THE SATURATED LAYERS BELOW...AND A FEW LOCATIONS REPORTED U.P. AND OR FZDZ. FOR OUR AREA...AFTER THE FRONT MOVES THROUGH...LOWER LEVEL MOISTURE WILL REMAIN BUT PROFILES ARE STILL INDICATIVE OF LIQUID PRECIP AND SURFACE TEMPS WILL REMAIN ABOVE FREEZING. THE HRRR AND RUC BOTH HAVE A GOOD HANDLE ON THE WESTERN EDGE OF THE PRECIP AND FRONTAL LOCATION...AND MOST OF IT SHOULD CLEAR THE ROCKFORD CORRIDOR NEAR SUNRISE...WITH CHICAGO AND EAST JUST A FEW HOURS BEYOND. WHILE LOWER LEVEL RH WILL REMAIN PREVALENT WITH AND SHORTLY BEYOND FROPA...MOISTURE ABOVE -10C WILL DISAPPEAR AND THERE MAY BE SOME LINGERING DZ INTO THE EARLY MORNING HOURS. THE BIG PUSH OF COLDER AIR ISNT EXPECTED UNTIL LATER THIS EVENING AND TEMPERATURES WILL REMAIN ABOVE FREEZING...SO NO CONCERN OVER ANY OTHER PRECIP TYPES THIS MORNING. HIGH TEMPS WILL GENERALLY BE SEEN EARLY TODAY...AND SLOWLY FALL THROUGH THE DAY. WINDS WILL ABATE AS HIGH PRESSURE AND A PERIOD OF DRY...SLOWLY MOVE IN. THE MAIN UPPER LEVEL TROUGHING THAT STRETCHES FROM ROUGHLY SASKATCHEWAN...SOUTHWEST THROUGH THE FOUR CORNERS REGION WILL NOT HAVE MUCH REASON TO MOVE UNTIL THE START OF THE WORKWEEK. PRESENT SHORTWAVE SEEN ON WATER VAPOR IMAGERY ROUNDING THE BASE OF THE TROUGH...ACROSS SOUTHERN ARIZONA...WILL DAMPEN SOME AS IT GETS EJECTED ON THE EASTERN FLANK TODAY AND TONIGHT. AS IT DOES THIS...IT WILL HELP TO AMPLIFY AN INVERTED TROUGH THAT WILL NOSE ITS WAY TOWARDS THE OHIO VALLEY...EVENTUALLY SPAWNING A WEAK LOW ACROSS THE TENNESSEE VALLEY. GUIDANCE HAS BEEN HEMMING AND HAWING WITH JUST HOW FAR NORTH TO BRING THE PRECIP WITH THIS FEATURE...AND JUST HOW MUCH OF IT WILL REACH INTO THE SOUTHEASTERN CORNER OF THE CWA. THE LATEST FORECAST TRENDS HAVE BACKED OFF FROM PREVIOUS...AND DID SCALE BACK ON POPS AS WELL AS COVERAGE. STILL A LITTLE UNCERTAIN WITH WHERE THE RASN VS STRAIGHT RA LINE WOULD BE AND WILL MAINTAIN A SORT OF MIX. ALSO OF NOTE FOR COASTAL LOCATIONS IN THIS SAME TIME FRAME /AS THE INV TROF-LOW SLIDE EAST/ IS THE CHANCE FOR LES. THERMAL PROFILES ACROSS THE SOUTHERN LAKE WILL BECOME INCREASINGLY UNSTABLE WITH LAKE SURFACE TO H85 DELTA T`S REACHING THE 12-15C RANGE. EXPECT WEAK SHOWERS TO BEGIN TO STRETCH FROM LAKE COUNTY IL...EVENTUALLY SOUTH TO COOK AND GRADUALLY INTO THE MORE TYPICAL LAKE/PORTER IN ORIENTATION. QPF AMOUNTS NOT LOOKING VERY IMPRESSIVE DURING THE SHORT DURATION AND WOULD ONLY EXPECT ANYWHERE FROM A TRACE TO MAYBE A TENTH OR TWO OF ACCUMULATION CLOSE TO THE LAKE TOMORROW AND INTO TOMORROW NIGHT. THIS WILL ALL BE FOLLOWED BY A FEW DAYS OF QUIET AS ANOTHER RIDGE OF HIGH PRESSURE SWINGS IN FROM THE NORTHWEST. A LATE WEEK SYSTEM IS STILL PART OF A LOW CONFIDENCE FORECAST. GFS HAD BEEN ADVERTISING A WEAK CLIPPER DROPPING FROM THE NORTHERN PLAINS... AND PREVIOUS EC SOLNS HAD SIMILAR...BUT THE 12Z FLIPPED AND DEVELOPED A SURFACE LOW THAT LIFTS THROUGH THE MISSISSIPPI VALLEY...INTO NORTHERN INDIANA...NORTHEAST THROUGH EASTERN ONTARIO. CONFIDENCE AT THIS POINT ON THAT EURO SOLN IS LOW AND WILL KEEP THE CHANCE OF SNOW AND NOT BUMP UP (OR DOWN) ANY CATEGORY UNTIL THE PICTURE IS A LITTLE CLEARER. THE 00Z SOLN BEGAN TO COME IN AND WAS BACK TO THE ORIGINAL PICTURE WITH THE CLIPPER RACING THROUGH. DESPITE THE LOWER CONFIDENCE IN THAT FEATURE LATE THIS WEEK...THE ONE PICTURE OF CLARITY WHAT WILL FOLLOW IT. ALL LONG RANGE GUIDANCE IS STILL INDICATING THAT THERE WILL BE A LARGE SURGE OF COLD AIR ENCROACHING AS AN UPPER LEVEL TROUGH SWINGS THROUGH. THERE ARE STILL SOME TIMING DIFFERENCES WITH HOW QUICKLY THE COLD AIR WILL DUMP IN...WHICH IS DUE IN PART TO THE LARGE MODEL DIFFERENCES MENTIONED MOMENTS AGO...BUT THE ONE THING THEY ALL AGREE ON IS HOW COLD THE LOWER LEVELS WILL GET INTO THE WEEKEND. EVEN A WEEK OUT...THE EC/GFS/GEFS/DGEX/GEM(NHEM THROUGH F144) ALL HIGHLIGHT H85 TEMPS PLUMMETING TO -16 TO -18 DEGREES...OR EVEN A FEW DEGREES COLDER. TRANSLATE THAT TO THE SURFACE AND IT WOULD BE POSSIBLE THAT HIGHS WOULD STRUGGLE TO GET OUT OF THE TEENS FOR MANY LOCATIONS AND OVERNIGHT LOWS LEADING INTO THE WEEKEND WOULD DIVE BOMB TO THE SINGLE DIGITS /BUT LIKELY A SMIDGEN WARMER IN THE CHICAGO METRO/. WITH THAT FORECAST STILL BEING OUT 6-7 DAYS...AND A SLEW OF OTHER WEATHER GOING ON THROUGH THE EARLY WEEK... WILL ONLY CONTINUE TO TREND DOWN FROM THE INHERITED LONG RANGE FORECAST. THE BIG SAVING GRACE IS THE LACK OF SOLID SNOW PACK. IF THAT WERE PRESENT...IT WOULD BE MUCH COLDER. SHEA && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * LIGHT SHOWERS ENDING * MVFR CIGS...POSSIBLY DROPPING TO AROUND 1000 FT THIS MORNING. * STRONG GUSTY SSW WINDS AND POTENTIAL FOR LLWS EARLY...WINDS VEERING WEST AND DIMINISHING BY MIDDAY. ALLSOPP //DISCUSSION...UPDATED 06Z... SHIELD OF RAIN CONTINUES TO LIFT NORTHEASTWARD ACROSS THE TERMINALS WITH COVERAGE BECOMING MORE BROKEN JUST TO THE SOUTHWEST. LOW PRESSURE RESPONSIBLE FOR THE RAIN IS MOVING NORTHEAST ACROSS EASTERN IOWA AND WILL CROSS NORTHERN LAKE MICHIGAN SUNDAY MORNING. SOUTH WINDS HAVE INCREASED MARKEDLY AHEAD OF THE LOW WITH GUSTS CURRENTLY IN THE 25-30 KT RANGE BUT THESE WILL DIMINISH TO 20-25 KT OVERNIGHT. LOWER CEILINGS NOW MAKING IT INTO THE TERMINALS WITH LOW END MVFR EXPECTED TO ARRIVE IN THE NEXT FEW HOURS WHERE IT HAS NOT ALREADY. RFD WILL LIKELY SEE IFR SOON WITH SOME POTENTIAL FOR PERIODS OF IFR ACROSS THE CHI METRO TERMINALS WITH A LOWER CHANCE AT GYY. LATEST TRENDS SHOW MVFR VSBY TO BE RATHER SPOTTY BUT STILL EXPECT IT TO OCCUR TONIGHT THOUGH CONFIDENCE IS REDUCED IN WHETHER OR NOT IT WILL BE STEADY OR MORE INTERMITTENT. SHOWERS SHOULD BEGIN TO WANE IN THE 9-12Z TIME FRAME...POSSIBLY A LITTLE LATER AT GYY. ANOTHER CONCERN IS LOW LEVEL WIND SHEAR. WINDS INCREASE TO 50-55 KT AT 2000 FT ACROSS THE AREA...THOUGH SURFACE GUSTS OF 25-30 KT AT THE CURRENT TIME ARE LIKELY LIMITING THE SHEAR FOR NOW...BUT AS GUSTS DIMINISH A BIT IN A FEW HOURS SHEAR RISK WILL AGAIN INCREASE. MVFR CEILINGS WILL CONTINUE THROUGH SUNDAY MORNING WITH IFR EXPECTED TO IMPROVE TO MVFR AT RFD DURING THE MORNING. SOUTH WINDS WILL TURN SOUTHWEST THEN WEST THROUGH THE MORNING WITH SOME GUSTS CONTINUING. EXPECT THAT CEILINGS WILL SLOWLY LIFT...THOUGH REMAIN MVFR...INTO EARLY AFTERNOON AS THE WEST WINDS USHER IN DRIER LOW LEVEL AIR. TOUGH TO SAY IF VFR WILL BE REACHED BUT IT WOULD LIKELY TAKE UNTIL LATE AFTERNOON IF IT DOES...IF NOT EARLY EVENING. WINDS THEN SHIFT NORTHWEST EARLY SUNDAY EVENING. MDB //ORD AND MDW CONFIDENCE...UPDATED 09Z... * MEDIUM CONFIDENCE IN CIGS DROPPING TO 1000-1500 FT THIS MORNING THEN INCREASING TO 2000 FT OR BETTER THIS AFTERNOON. * HIGH CONFIDENCE IN VISIBILITY REMAINING 6 PLUS WITH JUST A FEW SPRINKLES THROUGH 12Z. * MEDIUM TO HIGH CONFIDENCE IN WIND FORECAST. ALLSOPP //OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z... MONDAY...VFR BUT POTENTIAL FOR IFR/MVFR IN LAKE EFFECT SNOW SHOWERS. TUESDAY...VFR. WEDNESDAY...VFR. THURSDAY...VFR. FRIDAY...VFR. SLIGHT CHANCE OF LIGHT SNOW. MDB && .MARINE... 133 AM CST A POWERFUL STORM WAS MOVING THROUGH THE GREAT LAKES THIS MORNING. LOW PRESSURE WILL MOVE QUICKLY FROM WISCONSIN TO NORTHERN LAKE MICHIGAN THIS MORNING...THEN ON TO QUEBEC BY EVENING. EAST OF THE TRACK OF THE LOW A VERY STRONG SOUTHERLY LOW LEVEL JET WAS OCCURRING...WITH 50 KT WINDS JUST 1 TO 2 THOUSAND FEET OFF THE SURFACE. A STRONG INVERSION WAS LIMITING MIXING BUT GALE FORCE WINDS WERE WORKING DOWN TO THE LAKE SURFACE OVER THE SOUTH HALF WITH SOME GALE FORCE GUSTS ON THE EAST SIDE OF THE NORTH HALF OF THE LAKE. WINDS SHOULD DROP OFF PRETTY QUICKLY AS THE LOW MOVES RAPIDLY NORTHEAST TODAY AND GALES SHOULD END BY ABOUT NOON. PRESENTLY GALE WARNING GOES THROUGH MID AFTERNOON BUT IT MAY BE CANCELED EARLY. WINDS WILL VEER FROM SOUTH TO NORTHWEST THROUGH THE COURSE OF THE DAY. TONIGHT THROUGH MONDAY ANOTHER LOW WILL MOVE FROM THE TEXAS COAST UP THROUGH THE OHIO VALLEY WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. THIS WILL PRODUCE A PERIOD OF NORTHERLY WINDS ON LAKE MICHIGAN. THE REST OF THE WEEK HIGH PRESSURE WILL DOMINATE THE CENTRAL U.S. WHILE LOW PRESSURE BECOMES ANCHORED OVER NORTHEAST CANADA. THIS WILL PRODUCE A PROLONGED PERIOD OF WESTERLY WINDS OVER LAKE MICHIGAN FROM MID WEEK INTO THE WEEKEND. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 PM SUNDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
313 AM CST SUN DEC 4 2011 .SYNOPSIS... 06Z SFC ANALYSIS HAD A LOW SOUTHEAST OF KVOK AND ANOTHER AROUND KMXO. THE FRONT RAN BETWEEN THE TWO LOWS AND INTO NORTHERN MISSOURI. A WEAK TROF RAN FROM THE KMXO LOW TO NEAR KUIN. RADAR TRENDS SHOW THE STRATIFORM PRECIP HAS EXITED THE AREA WITH A NARROW BAND OF RAIN ASSOCIATED WITH THE FRONT MOVING INTO ILLINOIS FROM IOWA. DEFORMATION PRECIPITATION CONTINUES ACROSS IOWA BUT IS DECREASING IN OVERALL COVERAGE. DEW POINTS AHEAD OF THE FRONT WERE IN THE 40S AND 50S WITH 20S AND 30S BEHIND THE FRONT. && .SHORT TERM...TODAY AND TONIGHT... THE RUC 285K OMEGA AND 295K CONDENSATION PRESSURE DEFICIT FIELDS ALONG WITH F VECTOR CONVERGENCE DEPICTS REASONABLY WELL WHAT IS CURRENTLY GOING ON. THE COLD FRONT WILL BE OVER THE EXTREME EASTERN CWFA JUST PRIOR TO SUNRISE WITH ITS ASSOCIATED RAIN BAND. THIS RAIN BAND WILL EXIT THE EASTERN CWFA 13-15Z. ACROSS THE WESTERN CWFA WET BULB SFC TEMPERATURES ARE DROPPING BELOW 34 DEGREES AND CONDENSATION PRESSURE DEFICITS ARE RISING. WHERE THE WET BULB SFC TEMPERATURES ARE 32 OR BELOW THE PRECIP CHANGES TO SNOW WITH SOME PATCHY FZDZ. RUC TRENDS SHOW WET BULB TEMPERATURES DROPPING THROUGH SUNRISE SO THERE IS A POTENTIAL FOR SOME LIGHT SNOW AND PATCHY FREEZING DRIZZLE ROUGHLY WEST OF A DUBUQUE TO FAIRFIELD LINE. HOWEVER...WITH THE DEFORMATION ZONE AND FORCING WEAKENING ALONG WITH CONDENSATION PRESSURE DEFICITS RISING THE PRECIPITATION WILL LIKELY BE MORE FLURRIES AND PATCHY FREEZING DRIZZLE. RUC TRENDS INDICATE THE PRECIPITATION IN THIS AREA WILL END BY MID MORNING. THUS TO HANDLE THE CURRENT TRENDS...THERE WILL BE A PRE-FIRST PERIOD TO REFLECT PRECIPITATION TRENDS. TEMPERATURES WILL CONTINUE TO FALL WITH MINS BEING ACHIEVED AROUND 14Z. BASED ON THE CAA...TEMPERATURES WILL LIKELY CONTINUE FALLING THROUGH MID MORNING BEFORE STARTING A SLOW RISE. MAX TEMPERATURES IN THE EASTERN CWFA WILL BE EARLY THIS MORNING WHILE WESTERN AREAS WILL SEE MAX TEMPERATURES THIS AFTERNOON. TONIGHT...QUIET AND DRY WX IS EXPECTED WITH A VERY SLOW CLEARING OF THE CLOUDS. ..08.. .LONG TERM...MONDAY THROUGH SATURDAY MONDAY THROUGH TUESDAY WE WILL BE ON THE COLD SIDE THAT MOVES THROUGH THE AREA TODAY AND SHOULD BE DRAPED FROM LOUISIANA NORTHEAST TO OHIO AND FARTHER NORTHEAST. THE UPPER LEVEL TROUGH WILL STILL BE WORKING THROUGH THE AREA...AND THE 500MB TROUGH AXIS IS NOT DUE TO GET PAST THE AREA UNTIL TUESDAY NIGHT. WHILE WE LOSE THE MID AND UPPER LEVEL MOISTURE...SOME TRAPPED MOISTURE HANGING AROUND 900MB AND BELOW WILL KEEP THE TIME PERIOD MOSTLY CLOUDY IF NOT CLOUDY ...NOT CLEARING UNTIL TUESDAY AFTERNOON. THE MODELS ARE INDICATING SOME CLEARING ON MONDAY MORNING...BUT THIS FILLS BACK IN AS NORTH WINDS ADVECT CLOUDS BACK OVER THE AREA IN THE CYCLONIC FLOW. WILL HAVE TO WATCH THESE TRENDS...AND WILL TREND PESSIMISTIC FOR NOW AS IT IS THE TIME OF YEAR FOR GLOOMY CONDITIONS. TEMPERATURES TO BE MODERATED BY THESE CLOUDS...BUT BELOW NORMAL VALUES CAN BE EXPECTED WITH THE COLD AIR ADVECTION GOING ON. HIGHS MONDAY IN THE 30S TO DROP INTO THE MID 20S TO MID 30S FOR TUESDAY. WITH ALL THE LOW CLOUDS AROUND...WE MAY GET A FEW FLURRIES OR EVEN PATCHY DRIZZLE...BUT HAVE ONLY PUT IN FLURRIES FOR NOW. TUESDAY NIGHT THE CLOUDS SHOULD FINALLY CLEAR...HAVE HAVE GONE WITH MUCH COLDER MIN TEMPS IN THE TEENS AND LOWER 20S. BY WEDNESDAY THE MAIN UPPER LEVEL TROUGH AXIS SWINGS EAST OF THE AREA...LEAVING US WITH CYCLONIC NORTHWEST FLOW. ALREADY...A COLD FRONT IS EXPECTED TO SWING THROUGH ON WEDNESDAY...AND WITH LITTLE MOISTURE AVAILABLE DO NOT EXPECT ANY PRECIPITATION. A SECOND COLD FRONT ALONG WITH AN UPPER LEVEL SHORTWAVE IS EXPECTED THROUGH THURSDAY OR THURSDAY EVENING...AGAIN SOMEWHAT LACKING IN MOISTURE...BUT IT MAY BE ABLE TO PRODUCE SOME PRECIPITATION THURSDAY NIGHT ALONG AND BEHIND IT. HOWEVER...THE MODELS HAVE LITTLE IN THE WAY OF RUN TO RUN CONSISTENCY WITH THIS FEATURE RIGHT NOW...AND HAVE STAYED FAIRLY CLOSE TO A CONSENSUS FORECAST FOR THIS TIME RANGE. TEMPERATURES IN THE NORTHWEST FLOW TO BE COLDER THAN NORMAL...WITH HIGHS ONLY GETTING INTO THE 30S...AND MINS IN THE TEENS AND 20S. FRIDAY WE WILL BE IN DEEP NORTHWEST FLOW ON THE WEST SIDE OF THE LONGWAVE TROUGH WITH SOME WEAK RIDGING AT THE SURFACE. BY SATURDAY THE LONGWAVE TROUGH WILL HAVE SHIFTED FURTHER EAST...AND WARM AIR ADVECTING BEGINS AGAIN AT MID LEVELS...WITH SOUTHWEST FLOW DEVELOPING AT THE SURFACE. THESE PERIODS SHOULD BE DRY WITH COLDER TEMPERATURES AGAIN. ..LE.. && .AVIATION... /ISSUED 1142 PM CST SAT DEC 3 2011/ A SURFACE LOW OVER NORTHEAST IOWA WILL CONTINUE TO MOVE NORTHEAST AWAY FROM THE AREA. EXPECT SOME IFR OR LIFR CIGS/VSBYS FOR A FEW HOURS EARLY THIS MORNING THEN WITH WEST TO NORTHWEST WINDS SPREADING OVER THE AREA THE CIGS/VSBYS SHOULD BE IMPROVING TO MVFR BY 12Z TO 15Z. THE RAIN WILL BE TAPERING OFF OVER THE AREA BY 09Z. A RN/SN MIX IS STILL POSSIBLE AT CID/DBQ BEFORE THE PRECIPITATION ENDS. FOR THE REST OF THE PERIOD EXPECT MVFR TO LOW END VFR CIGS SUNDAY AFTERNOON AND EVENING. ..DLF.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1142 PM CST SAT DEC 3 2011 .AVIATION... A SURFACE LOW OVER NORTHEAST IOWA WILL CONTINUE TO MOVE NORTHEAST AWAY FROM THE AREA. EXPECT SOME IFR OR LIFR CIGS/VSBYS FOR A FEW HOURS EARLY THIS MORNING THEN WITH WEST TO NORTHWEST WINDS SPREADING OVER THE AREA THE CIGS/VSBYS SHOULD BE IMPROVING TO MVFR BY 12Z TO 15Z. THE RAIN WILL BE TAPERING OFF OVER THE AREA BY 09Z. A RN/SN MIX IS STILL POSSIBLE AT CID/DBQ BEFORE THE PRECIPITATION ENDS. FOR THE REST OF THE PERIOD EXPECT MVFR TO LOW END VFR CIGS SUNDAY AFTERNOON AND EVENING. ..DLF.. && .PREV DISCUSSION... /ISSUED 308 PM CST SAT DEC 3 2011/ SYNOPSIS... MAIN FEATURE OF INTEREST IS THE UPPER LEVEL LOW OVER LAS VEGAS WITH A LEAD WAVE EJECTING OVER WESTERN KANSAS AT 18Z. MEANWHILE... SURFACE LOW IS LOCATED IN SOUTH-CENTRAL KANSAS WITH THE COLD FRONT EXTENDING NORTH TO FORT DODGE /KFOD/ AND THE UPPER PENINSULA. TEMPS BEHIND THE FRONT DIVE FROM THE MID AND SOME UPPER 40S INTO THE LOWER 30S. LARGE AREA OF RAIN IN THE WARM SECTOR LIFTED NORTH TODAY WITH PRECIP AMOUNTS TYPICALLY IN THE ONE HALF TO ONE INCH RANGE. NEXT ROUND OF PRECIP ASSOCIATED WITH THE MAIN COLD FRONT NOW SPANNING CENTRAL IOWA AND MUCH OF MISSOURI. SHORT TERM...TONIGHT AND SUNDAY... MAIN FORECAST CONCERN TONIGHT IS THE BEHAVIOR OF THE NEXT ROUND OF PRECIP. RUC BRINGS THE SURFACE LOW OVER VINTON /KVTI/ BY 03Z THIS EVENING. THIS IS SLIGHTLY FASTER AND FARTHER NORTHWEST THAN MODEL FORECASTS HAD BEEN BUT IS IN LINE WITH THE OVERALL TREND TO A WARMER FORECAST. IN TERMS OF PRECIP...THIS MORE WESTERN TRACK...AS SEEN IN THE RUC AND CURRENT RADAR TRENDS...SUGGESTS RAIN THROUGH THE EVENING WITH ONLY A BRIEF CHANGE TO SNOW IN THE FAR NORTHERN COUNTIES BEFORE PRECIP ENDS LATE TONIGHT/EARLY SUNDAY MORNING. MUCH OF THE AREA TO BE DRY-SLOTTED OVERNIGHT WITH ONLY THE NORTHERN AND WESTERN SECTIONS EXPECTED TO SEE WRAP-AROUND PRECIP AS THE LOW RACES OFF TO THE NORTHEAST. EVEN SO...BUFKIT SOUNDINGS FOR KCID AND KDBQ LIMIT ANY FROZEN PRECIP TO ONLY AN HOUR OR TWO BEFORE ENDING ALTOGETHER. THUS HAVE REDUCED SNOW AMOUNTS AND ENDED PRECIP A FEW HOURS EARLIER THAN PREVIOUS FORECAST. ..DMD.. LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY HIGH PRESSURE AT THE SURFACE MIGRATING THROUGH THE NORTHERN PLAINS INTO THE UPPER MS VALLEY TO BRING NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES FROM SUNDAY NIGHT THROUGH WEDNESDAY. THROUGH THIS PERIOD...MODELS IN GENERAL AGREEMENT FEATURING AN UPPER LEVEL POSITIVE TILT LONG WAVE TROUGH TRANSITIONING EAST THROUGH THE CENTRAL U.S....SUPPRESSING THE MAIN BAROCLINIC AXIS AND STORM TRACK WELL TO THE SOUTHEAST. A WAVE OF LOW PRESSURE TRACKING ALONG THE OHIO RIVER MONDAY WILL SPREAD SNOW INTO PORTIONS OF MO AND IL...AND WILL KEEP ONLY SLIGHT CHANCE POPS CONFINED TO THE FAR EAST AND SOUTH MONDAY NIGHT ON THE EXTREME NW EDGE OF THIS SYSTEM. OTHERWISE...NO PRECIPITATION IS EXPECTED...BUT HIGH LEVEL LIFT AND MOISTURE ALOFT AHEAD OF THE UPPER TROUGH AXIS WILL FAVOR MOSTLY CLOUDY SKIES FOR MUCH OF MON THROUGH WED. THU THROUGH SAT...MODEL CONSENSUS INDICATES A COLD FRONT DROPPING SOUTH THROUGH THE REGION LATE THURSDAY...FOLLOWED BY MUCH COLDER TEMPERATURES FRIDAY AND SATURDAY FOLLOWING A FRESH INFLUX OF COLD AIR AT 850 MB THAT HAS BEEN BUILDING WELL TO THE NORTH. THERE CONTINUES TO BE CONSIDERABLE DIFFERENCES WITH THE TIMING AND PLACEMENT OF CRITICAL UPPER LEVEL TROUGHS AND SURFACE FEATURES IN THIS TIME FRAME...THUS THE POTENTIAL FOR PRECIPITATION REMAINS LOW CONFIDENCE. THE CURRENT SUITE OF MODELS USED IN THE EXTENDED SUPPORTS OUR SLIGHT TO LOW END CHANCES FOR LIGHT SNOW FOR THU NIGHT FOLLOWING THE PASSAGE OF THE COLD FRONT. AHEAD OF THIS FRONT...HIGHS THURSDAY SHOULD REACH INTO THE 30S IN MOST AREAS. THIS IS FOLLOWED BY 20S FRIDAY AND SATURDAY WITH OVERNIGHT LOWS IN THE SINGLE DIGITS AND TEENS. ..SHEETS.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
1211 AM CST SUN DEC 4 2011 .UPDATE... UPDATED FOR THE 06Z AVIATION DISCUSSION BELOW. .DISCUSSION... SNOW HAS BEGUN TO SPREAD INTO S MN AND WILL CONTINUE TO EXPAND NE RAPIDLY DURING THE REMAINDER OF THE AFTERNOON. A BIT OF SATURATION LEFT TO DO IN LOWER LEVELS BUT CIGS ARE BEGINNING TO LOWER ACROSS S MN. IR SATELLITE SHOWS ELONGATED VORT FROM W KS INTO SC NEB LIFTING NE. GFS/NAM SIMILAR ON TIMING BRINGING MAIN VORT INTO SC MN BY 00Z AND THEN LIFTING INTO CENTRAL WI BY 06Z. GFS HAS INCREASED QPF VALUES A BIT MORE TOWARD THE NAM SOLUTION. INCREASED SNOW AMOUNTS A BIT ACROSS AREAS FROM MKT TO SE METRO BASED LARGELY ON TRACK OF SURFACE/850 MB LOW CENTERS. HEAVY SNOW OFTEN SETS UP 70 TO 90 MILES N OF 850 MB LOW TRACK..AND 850 MB LOW TRACKS FROM SW IA TO JUST S OF LSE BY 06Z THEN INTO E UPR MICHIGAN BY 12Z. KEPT SNOW AMOUNTS IN THE 3 TO 6 INCH ADVISORY. FAVORABLE ISENTROPIC LIFT COMES THRU RATHER QUICKLY WITH 3-3.5G/KG SO HESITATE TO GO ANY HIGHER. WILL BE A PERIOD FROM AROUND 22Z TO 05Z WHERE ADVISORY AREA WILL BE UNDER STRONG UPPER DIVERGENGE FROM COUPLED UPPER JET... FAVORABLE DENDRITIC TEMPERATURES AND STRONG 600 MB FULL WIND FRONTOGENSIS WHICH COULD BRING A PERIOD OF A FEW HOURS OF VISIBILITY INTO THE 1/2 SM RANGE AS FAR N AS MSP. LIKE THE TIMING OF THE RUC BUFKIT SNOW ACCUMS IN THAT WINDOW. DECREASED SNOW AMOUNTS SLIGHTLY IN W SIDE OF ADVY AREA AROUND SPRINGFIELD AND GAYLORD. ADVISORY WILL LIKELY BE ABLE TO BE EXPIRED BY 06Z ACROSS MUCH OF THE MN CWA WITH NO SIGNIFICANT WIND EXPECTED IN WAKE OF SNOW. COOLER FOR SUNDAY...BUT TROF DROPPING OUT OF CANADA WILL BACK WINDS ENUF TO KEEP MAIN PUSH OF COLD AIR NORTH OF AREA. AS THIS SYSTEM MOVES THRU COLD AIR WILL MOVE IN FOR MONDAY WITH HIGHS ONLY IN THE TEEN TO MID 20S. SLIGHT MODERATION FOR WEDNESDAY AS WEAK TROF MOVES ACROSS AREA. AFTER THAT AREA REMAINS IN COLD AND DRY NW FLOW AT LEAST UNTIL NEXT WEEKEND. WITH SNOW COVER EXPECTED TONIGHT ACROSS S MN INTO WC WI WILL BE SOME SOME MORNINGS WHERE WE SHOULD GET MIN TEMPS DOWN NEAR ZERO...TUESDAY AND PROBABLY AGAIN FRIDAY/SATURDAY. .AVIATION.../06Z TAF ISSUANCE/ HAVE THE SNOW CLEARING EAST CENTRAL MN BY ROUGHLY 09Z PER THE SHARP CLEARING EDGE TO THE BACK OF THE RADAR NOW. LIKELY LOSE IFR VISIBILITY BY AROUND 08Z IN MN DUE TO THE DECREASING SNOW RATES. KEAU MAY STILL SEE CONDITIONS GET POORER FOR A COUPLE HOUR WINDOW THIS MORNING BEFORE IMPROVING CLOSER TO SUNRISE. IN TERMS OF CLOUDS...THE CONDITIONAL CEILINGS WHEN SNOW IS FALLING COULD CREATE SHORT PERIODS OF IFR CEILINGS OVER THE NEXT FEW HOURS...BUT OVERALL WE ARE MAINLY STUCK WITH A MVFR DECK. THIS MIGHT BE WITH US FOR SOME TIME. DOING A SIMPLE EXTRAPOLATION OF THE BACK EDGE OF THE STRATUS GETS CLEARING INTO WESTERN MN BY AROUND 12Z. HOWEVER...GIVEN THE TIME OF YEAR AND DUE TO THE FACT WE REALLY DON`T SEE MUCH OF A PATTERN CHANCE UNTIL MONDAY...TRENDED PESSIMISTIC WITH THE MVFR CEILINGS. KMSP...VISIBILITY HAS IMPROVED OVER THE LAST HOUR AT THE AIRPORT AND SHOULD SEE THE SNOW TAPER TO NOTHING BY AROUND 09Z. THE CEILINGS HAVE TEMPORARILY JUMPED UP TO 3500FT...BUT WITH LOWER CEILINGS TO THE WEST...IT SHOULD ONLY BE A MATTER OF TIME BEFORE MVFR STRATUS MOVES BACK IN AND LINGERS FOR MOST OF THE DAY. HOWEVER...FAIRLY CONFIDENT WE`LL REMAIN ABOVE 2000FT MUCH OF THE TAF PERIOD. WIND DIRECTION WILL REMAIN OUT OF THE NORTHWEST AND GRADUALLY DECREASE AFTER SUNRISE. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR ANOKA-BLUE EARTH-BROWN-CARVER-CHISAGO-DAKOTA-FARIBAULT-FREEBORN- GOODHUE-HENNEPIN-LE SUEUR-MARTIN-NICOLLET-RAMSEY-RICE-SCOTT- SIBLEY-STEELE-WASECA-WASHINGTON-WATONWAN. WI...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX. && $$ BAP/CLF
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
311 AM CST SUN DEC 4 2011 .DISCUSSION... LIGHT SNOW WHICH AFFECTED PORTIONS OF OUR AREA ON SATURDAY HAS PUSHED INTO CENTRAL MINNESOTA AND CENTRAL IOWA VERY EARLY THIS MORNING. BEHIND THE EXITING SYSTEM...A BROAD AREA OF STRATUS HAS DEVELOPED ACROSS THE EASTERN DAKOTAS INTO EASTERN NEBRASKA...THOUGH MODELS NOT PICKING UP ON THIS AT ALL. 06Z RUC 925 MB RH TIME SECTION HINTING AT IT...AND HAS IT PULLING EASTWARD THROUGH THE MORNING...EXITING OVER OUR FAR EAST BY 18Z. OTHERWISE...A RELATIVELY QUIET DAY IN STORE...WITH CLOUDS INCREASING IN OUR WEST IN THE AFTERNOON AS A WEAK SHORTWAVE DROPS SOUTHWARD ON A NORTHWESTERLY UPPER LEVEL FLOW. NOT MUCH IN THE WAY OF DYNAMICS WITH THIS FEATURE...BUT COULD SPIT OUT SOME VERY LIGHT SNOW IN OUR WEST BY LATE THIS AFTERNOON INTO TONIGHT. TEMPERATURES A BIT TRICKY TODAY IN BETWEEN CLOUD COVER...THOUGH WHAT IS MORE CERTAIN IS THAT READINGS WILL NOT WARM A WHOLE LOT OVER SNOW COVERED AREAS...WITH HIGHS GENERALLY IN THE MID 20S THROUGH NORTHWESTERN IOWA AND PORTIONS OF SOUTHWESTERN MINNESOTA. TO THE WEST...WITH MORE SUN AND BETTER MIXING IN A TRANSITIONING SOUTHWESTERLY LOW LEVEL FLOW...HIGHS WILL REACH THE MID 30S ACROSS THE MUCH OF THE JAMES RIVER VALLEY INTO SOUTH CENTRAL SOUTH DAKOTA. WINDS WILL BECOME NORTHWESTERLY AND PICK UP FROM WEST TO EAST TONIGHT IN A TIGHTENING GRADIENT AND COLD AIR ADVECTION BEHIND THE EXITING SHORTWAVE AND SURFACE LOW/ASSOCIATED FRONTAL BOUNDARY. THE WINDS AND CLOUD COVER WILL KEEP OVERNIGHT LOWS SOMEWHAT IN CHECK...THOUGH WILL STILL DROP INTO THE TEENS...EXCEPT SINGLE DIGITS OVER SNOW COVER. COLDER AIR WILL CONTINUE TO FILTER INTO THE REGION ON MONDAY WITH A SURFACE HIGH BUILDING INTO THE REGION. TEMPERATURES WILL NOT RISE MUCH FROM EARLY MORNING LOWS...WITH HIGHS ONLY IN THE UPPER TEENS TO LOWER 20S. SOUTHERLY FLOW RETURNS TO THE REGION ON TUESDAY BEHIND THE EXITING HIGH...AND TEMPERATURES TRY TO WARM A BIT IN THE WEST...INTO THE MID AND UPPER 20S...WHILE READINGS OVER SNOW COVERED AREAS MAY ACTUALLY BE A LITTLE COOLER THAN MONDAYS HIGHS WITH LESS MIXING...REMAINING ONLY IN THE UPPER TEENS. EVEN WARMER ON WEDNESDAY AHEAD OF THE NEXT ARCTIC SURGE WHICH WILL DIVE SOUTHWARD ON WEDNESDAY NIGHT AND THURSDAY. COULD GET A LITTLE SNOW ALONG THE LEADING EDGE OF THIS SURGE/FRONTAL GRADIENT DURING THAT TIME FRAME...THOUGH ANY SNOW SHOULD BE LIGHT. HIGHS ON WEDNESDAY WILL BE IN THE UPPER 20S TO MID 30S...THEN DROP BACK TO THE LOWER TO MID 20S ON THURSDAY. FRIDAY LOOKS TO BE THE COLDEST DAY OF THE WEEK...WITH HIGHS MID TEENS TO AROUND 20...FOLLOWED BY SOME WARMING ON SATURDAY. LOOKS TO REMAIN DRY BOTH DAYS. && .AVIATION.../FOR THE 06Z TAF ISSUANCE/ DRIER AIR MASS SETTLING INTO THE AREA TONIGHT. SNOW BAND LINGERING IN THE EXTREME SOUTHEAST CORNER OF THE CWA SHOULD EXIT THE AREA WITHIN THE NEXT HOUR OR SO. LATEST SATELLITE IMAGERY SHOWS RELATIVELY FAST MOVING AND NARROW TONGUE OF LOW STRATUS TRACKING SOUTHEAST ACROSS EASTERN NORTH DAKOTA AND INTO NORTHEAST AND SOUTH CENTRAL SOUTH DAKOTA. MVFR CEILINGS AROUND 2500 TO 3000 FEET WILL BE ASSOCIATED WITH THIS BAND WHICH WILL TRACK ACROSS THE ENTIRE CWA INTO THE EARLY MORNING HOURS. DESPITE A FRESH SNOWPACK ACROSS THE SOUTHEASTERN HALF...RELATIVELY LIGHT WINDS AND LATE CLEARING TONIGHT...THINK THAT THE AIRMASS WILL BE TOO DRY TO SUPPORT FOG ALTHOUGH IT WILL BE SOMETHING TO CONTINUE TO MONITOR. VFR CONDITIONS AND RELATIVELY LIGHT WINDS ON TAP FOR SUNDAY. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. && $$
AREA FORECAST DISCUSSION
NWS AUSTIN/SAN ANTONIO TX
1149 PM CST SAT DEC 3 2011 .AVIATION... A WIDESPREAD AREA OF SHRA WITH EMBEDDED TSRA HAS DEVELOPED ACROSS CENTRAL TEXAS. ADDITIONAL DEVELOPMENT IS EXPECTED THROUGH THE OVERNIGHT HOURS AS THIS SYSTEM PROGRESSES SOUTHWARD AHEAD OF AN APPROACHING COLD FRONT WITH THE POTENTIAL FOR PERIODS OF -SHRA AND TEMPO -TSRA. A PRE-FRONTAL TROUGH AHEAD OF THE COLD FRONT WILL ENABLE SFC WINDS TO GRADUALLY BACK FROM SE TO E THROUGH THE NEXT FEW HOURS BEFORE THE FRONT ARRIVES BETWEEN 09-12Z ACROSS THE REGION. MVFR CIGS STRETCH FROM KJCT TO KBMQ TO KTPL AND ARE EXPECTED TO REACH THE SOUTH CENTRAL TEXAS TAF SITES BY 07Z. CIGS WILL DETERIORATE TO IFR AND POTENTIALLY LIFR THROUGH THE OVERNIGHT HOURS. ADDITIONALLY...AHEAD OF THE FRONT...A MIX OF -DZ/BR/-SHRA WILL LOWER VSBYS TO MVFR/IFR PARTICULARLY AT KAUS/KSAT/KSSF. THE COLD FRONT WILL ARRIVE SUNDAY MORNING...BUT IMPROVEMENTS TO CIGS AND VSBYS WILL BE SLOW WITH VFR CONDITIONS STILL NOT EXPECTED TO RETURN DURING THE 24-HR NOR 30-HR TAF PERIODS. && .PREV DISCUSSION... /ISSUED 933 PM CST SAT DEC 3 2011/ UPDATE... PRE-FRONTAL TROUGH EXTENDS FROM WACO TO LAMPASAS TO JUNCTION TO DRYDEN WHILE CANADIAN COLD FRONT EXTENDS FROM WICHITA FALLS TO ABILENE TO MIDLAND. TROUGH AND FRONT HAVE SPEED UP SLIGHTLY AND NEW 00Z NAM AND RUC BRING THESE FEATURES THROUGH SOUTH CENTRAL TEXAS A LITTLE EARLIER THAN PREVIOUSLY FORECAST WHICH SEEMS REASONABLE. MAIN IMPACTS ARE TO GO WITH COOLER TEMPERATURES AND EARLIER WIND SHIFTS TO NORTHERLY ON SUNDAY...ESPECIALLY DURING THE LATE MORNING AND AFTERNOON ALONG WITH LOWER POST-FRONTAL DEWPOINTS FOR SUNDAY THROUGH MONDAY. REMAINDER OF YOUR SOUTH CENTRAL TEXAS FORECAST IS ON TRACK. PREV DISCUSSION... /ISSUED 538 PM CST SAT DEC 3 2011/ AVIATION... A BRIEF WINDOW OF VFR CONDITIONS WILL CONTINUE THROUGH THE NEXT FEW HOURS BEFORE THE ONSET OF MVFR CIGS BY ABOUT 03Z. STREAMER SHOWERS WILL CONTINUE TO DEVELOP MAINLY EAST OF A LINE FROM KERV TO KHDO TO KCOT THROUGH THE EVENING HOURS AS WARM AIR ADVECTION PERSISTS IN ADVANCE OF AN APPROACHING COLD FRONT. THE DEEP MOISTURE IN THE LOWER LEVELS WILL PROMOTE THE DETERIORATION OF CIGS TO IFR AND POTENTIALLY LIFR CONDITIONS OVERNIGHT. AHEAD OF THE FRONT...A MIX OF -DZ/BR/-SHRA IS EXPECTED TO LOWER VSBYS TO MVFR/IFR PARTICULARLY AT KAUS/KSAT/KSSF. THE COLD FRONT WILL ARRIVE SUNDAY MORNING...BUT IMPROVEMENTS TO CIGS AND VSBYS WILL BE SLOW WITH VFR CONDITIONS NOT EXPECTED TO RETURN DURING THE 24-HR NOR 30-HR TAF PERIODS. PREV DISCUSSION... /ISSUED 314 PM CST SAT DEC 3 2011/ DISCUSSION... PRE-FRONTAL TROUGH/DRY LINE HAS PUSHED INTO THE FAR WESTERN CWA THIS AFTERNOON WITH GOOD MIXING/CLEARING ACROSS THE WESTERN COUNTIES. THE SKIES OVER THE EASTERN COUNTIES GENERALLY ALONG AND EAST OF I35 HAVE REMAINED MOSTLY CLOUDY WITH PATCHY LIGHT RAIN AND DRIZZLE CONTINUING IN THE DEEP SLY GULF FLOW. RAIN CHANCES WILL INCREASE AGAIN LATER THIS EVENING INTO THE OVERNIGHT HOURS AND SUNDAY. COMBINATION OF UPPER AIR DISTURBANCES IN THE SWLY FLOW ALOFT...CONVERGENCE ALONG THE PRE-FRONTAL SURFACE TROF...AND THE INCREASING LOW LEVEL GULF FLOW WILL RESULT IN GOOD CHANCES FOR DEEP CONVECTION. BECAUSE OF THE DEEP GULF INFLOW AHEAD OF THE TROUGH...WILL SEE GENEROUS QPF VALUES ESPECIALLY ACROSS THE NE/ERN COUNTIES. RAINFALL AMOUNTS OF ONE HALF TO ONE INCH OVER THE NEXT 24 HOURS WITH ISOLATED STORM TOTALS OF NEAR 2 INCHES POSSIBLE. THE COLD FRONT WAS PUSHING THROUGH THE TX PANHANDLE THIS AFTERNOON AND MODELS HAVE SLOWED THE PROGRESSION THRU S TX ON DURING THE DAY ON SUNDAY. CURRENT THINKING IS A FRONTAL PASSAGE INTO THE NRN HILL COUNTRY/EDWARDS PLATEAU BY 6 AM AND TO NEAR I10/HIGHWAY 90 BY AROUND NOON...AND THRU THE REMAINDER OF THE CWA BY 5 PM. HIGH TEMPERATURES WILL OCCUR JUST AHEAD OF THE COLD FRONT AND TEMPS ACROSS THE SRN CWA COULD REACH THE MID OR UPPER 70S. WILL SEE SLOWLY FALLING TEMPERATURES BEHIND THE FRONT AS COLD AIR ADVECTION WILL BEHIND TO INCREASE LATE SUNDAY NIGHT INTO MONDAY. MONDAY WILL BE THE MORE BONE CHILLING DAY WITH THE COMBINATION OF COLD...WIND AND POST FRONTAL OVERRUNNING LIGHT RAIN. WINTER PRECIPITATION FOR THE FAR NRN COUNTIES APPEARS UNLIKELY GIVEN THE WARMER 12Z SOUNDING TEMP PROFILE FOR MONDAY NIGHT/TUESDAY MORNING...AND MOST PRECIPITATION WILL BE ENDING FROM THE WEST BY SUNRISE TUESDAY MORNING. GRADUAL CLEARING TUESDAY WITH ALLOW FOR A COUPLE OF NIGHTS OF FREEZING TEMPERATURES AREA WIDE TUESDAY NIGHT AND WEDNESDAY NIGHT. STRONG WESTERLY FLOW ALOFT WILL RESULT IN A QUICK RETURN OF MOISTURE AND OVERRUNNING SETTING UP FOR LATE THURSDAY INTO FRIDAY AHEAD OF THE NEXT COLD FRONT. ANOTHER FAIRLY GOOD SHOT OF COLD CANADIAN AIR WILL ARRIVE FRIDAY NIGHT INTO SATURDAY...HOWEVER IT DOES NOT APPEAR THERE WILL BE ANY POST FRONTAL PRECIPITATION AS A DRY WNWLY FLOW DEVELOP BEHIND A SHORT WAVE AS THE COLD AIR ADVECTION BEGINS. && .PRELIMINARY POINT TEMPS/POPS... AUSTIN CAMP MABRY 54 58 44 49 36 / 80 80 90 60 20 AUSTIN BERGSTROM INTL AIRPORT 57 59 43 50 34 / 80 80 90 60 30 NEW BRAUNFELS MUNI AIRPORT 62 63 44 50 35 / 70 70 80 50 20 BURNET MUNI AIRPORT 47 49 40 47 35 / 80 80 90 50 20 DEL RIO INTL AIRPORT 55 56 45 52 36 / 50 30 50 20 10 GEORGETOWN MUNI AIRPORT 52 55 40 47 34 / 80 80 90 60 20 HONDO MUNI AIRPORT 63 63 45 53 35 / 70 50 80 30 20 SAN MARCOS MUNI AIRPORT 61 63 45 48 36 / 70 70 90 50 30 LA GRANGE - FAYETTE REGIONAL 64 67 48 50 38 / 70 80 90 70 30 SAN ANTONIO INTL AIRPORT 62 63 46 53 37 / 70 60 80 40 20 STINSON MUNI AIRPORT 64 64 47 52 38 / 70 60 80 40 20 && .EWX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ MESOSCALE/AVIATION...25 SYNOPTIC/GRIDS...04
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1130 PM CST SAT DEC 3 2011 .AVIATION... SOME SLIGHTLY DRIER AIR IN THE LOW LEVELS HAS MOVED INTO THE REGION BEHIND THE INITIAL WIND SHIFT/WEAK FRONT. THIS HAS ALLOWED CIGS TO GO VFR EVERYWHERE BUT WACO. WITH MORE RAIN ON THE WAY OVERNIGHT EXPECT LOW LEVEL SATURATION TO OCCUR AND HELP BRING BACK MVFR CIGS AROUND SUNRISE...WITH IFR CIGS BY TOMORROW AFTERNOON. LIGHT RAIN WILL BE ALMOST CONTINUOUS THROUGH THE NEXT 24 HOURS BUT AGAIN WILL NEED LOW LEVEL SATURATION BEFORE VIS GETS AFFECTED. A COUPLE STORMS HAVE FORMED SW OF DFW TRACON AND WILL SHOW VCTS THROUGH 9Z THIS MORNING AS THESE CELLS MOVE THROUGH. AFTER THAT ANY THUNDER SHOULD BE VERY ISOLATED AND WILL KEEP WEATHER TYPE AS SHRA. GENERALLY IFR CIGS AND MVFR VIS EXPECTED SUNDAY AFTERNOON THROUGH MONDAY MORNING. WINTER POTENTIAL FOR DFW TRACON CONTINUES TO LOOK LOW WITH SUBFREEZING TEMPS NOT EXPECTED SUNDAY NIGHT OR MONDAY WHEN PRECIP IS OCCURRING. RAIN/SNOW LINE EARLY MONDAY MORNING SHOULD STAY JUST NW OF DFW TRACON. TR.92 && .UPDATE... PRECIP CONTINUES TO EXPAND IN AREAL COVERAGE OVER THE NORTHEAST QUADRANT OF THE CWA. LATEST RUC ANALYSIS SHOWS THE STRONG LIFT RESPONSIBLE FOR THE PRECIP ON THE 295K ISENTROPIC SURFACE. 35 KNOT SOUTHERLY WINDS ARE QUICKLY LIFTING MOIST PARCELS FROM 975 MB TO 875 MB AS THE COLDER AIR MASS MOVES EAST. UPPED POPS IN THE 0-6Z TIMEFRAME TO 100 PERCENT FOR AREAS EAST AND NORTH OF A SHERMAN TO DALLAS TO CANTON LINE GIVEN THE EXPECTED INTENSITY OF THIS LIFT AND CURRENT RADAR TRENDS. THE RUC SHIFTS THE BEST LIFT ASSOCIATED WITH THE COLD AIR WEDGE TO THE SOUTH LATER TONIGHT AND WILL HAVE 80 POPS FOR THE SOUTHERN ZONES AFTER 6Z. WIDESPREAD PRECIP IS EXPECTED TOMORROW BEHIND THE FRONTAL BOUNDARY AS WARM/MOIST AIR IS LIFTED OVER THE COLD AIR. BUMPED UP POPS TO 100 PERCENT FOR MOST OF THE CWA EXCEPT FOR THE NORTHWESTERN ZONES FOR THE SUNDAY PERIOD. 85/NH && .PREV DISCUSSION... /ISSUED 321 PM CST SAT DEC 3 2011/ SHORTWAVE DISTURBANCE CONTINUES TO LIFT UP THROUGH THE SOUTHERN PLAINS THIS AFTERNOON RESULTING IN THE SLOW EASTWARD PROGRESSION OF A BAND OF LIGHT TO MODERATE RAIN CURRENTLY ALONG A LINE FROM COMANCHE TO WEATHERFORD TO GAINESVILLE. LOW RAINFALL AMOUNTS FOR MOST AREAS...BUT SOME ISOLATED AMOUNTS TO BETWEEN A QUARTER AND HALF INCH WILL BE POSSIBLE AS THIS BAND MOVES ACROSS NORTH TEXAS. THE RAIN-COOLED AIR HAS RESULTED IN THE OLD FRONT SAGGING TO A GAINESVILLE TO DECATUR TO CISCO LINE THIS AFTERNOON WITH TEMPERATURES IN THE 50S BEHIND THE FRONT WHILE REMAINING IN THE 60S TO LOWER 70S AHEAD OF IT. A FEW EMBEDDED THUNDERSTORMS ARE POSSIBLE...BUT NOT LIKELY THROUGH THIS EVENING. A STRONGER COLD FRONT CAN BE SEEN NOW MOVING THROUGH THE HIGH PLAINS OF EASTERN CO/WESTERN KS THIS AFTERNOON. THE FRONT SHOULD ARRIVE INTO OUR FAR NORTHWEST COUNTIES BY MIDNIGHT...THEN QUICKLY PUSH TO AN ATHENS...WACO...LAMPASAS LINE BY SUNRISE SUNDAY. THE FRONT WILL CLEAR THE REMAINDER OF NORTH TEXAS BY LATE MORNING SUNDAY. THE STRONG COLD FRONT WILL OVERTAKE OUR CURRENT FRONT WITH THE BULK OF MODERATE RAIN AND ISOLATED THUNDERSTORMS OCCURRING AHEAD OF THE FRONT. SOME LIGHT RAIN WILL LIKELY REMAIN BEHIND THE FRONT. HIGHS SUNDAY WILL OCCUR BETWEEN MIDNIGHT AND MIDDAY SUNDAY...WITH FALLING AFTERNOON TEMPERATURES AND GUSTY NORTH WINDS 15 TO 20 MPH AFTER FROPA. THE GUSTY WINDS AND LIGHT RAIN WILL MAKE FOR A RAW AND WET DAY ACROSS NORTH TEXAS...THOUGH OVERALL HEAVIER RAINFALL SHOULD SHIFT TO THE SOUTH AND EAST OF OUR AREA LATE SUNDAY AFTERNOON AND EVENING. A MORE ROBUST SHORTWAVE DISTURBANCE ARRIVES LATE SUNDAY NIGHT INTO MONDAY AND WILL INDUCE ISENTROPIC ASCENT ONCE AGAIN WITH A COLD AND AT TIMES MODERATE RAIN ACROSS NORTH TEXAS. TEMPERATURES WILL LIKELY FALL INTO THE MID 30S BY DAYBREAK MONDAY MORNING ACROSS AREAS TO THE NORTHWEST OF THE DFW METROPLEX. MOST MODELS...INCLUDING SREF AND WRF ...ARE HOLDING THE DEEPER COLD AIR OFF TO THE NORTHWEST OF THIS AREA THROUGH MIDDAY MONDAY. DESPITE TEMPERATURES JUST ABOVE FREEZING...A RAIN/SNOW MIX COULD OCCUR ACROSS THIS AREA MONDAY MORNING AS THERMAL PROFILES COOL QUICKLY TO OR JUST BELOW FREEZING. COLD RAIN IS EXPECTED ELSEWHERE. REGARDING THE WINTER WEATHER POTENTIAL...AS THE SHORTWAVE MOVES QUICKLY ACROSS THE AREA...DRYING ABOVE THE BOUNDARY LAYER WILL FOLLOW IN ITS WAKE. AS A RESULT OF THIS DRYING...ICE CRYSTAL PRODUCTION WILL BE LIMITED AND A MIXTURE OF VERY LIGHT RAIN/ DRIZZLE/FLURRIES IS LIKELY. ISENTROPIC DOWNSLOPE CONTINUES DURING THE OVERNIGHT HOURS INTO TUESDAY MORNING WITH CLOUDS GRADUALLY DECREASING. NORTH TEXAS WILL REMAIN UNDER THE INFLUENCE OF CYCLONIC FLOW ALOFT THROUGH THE WEEK...RESULTING IN PARTLY CLOUDY SKIES AND COLD CONDITIONS. THE STUBBORN UPPER LOW FINALLY OPENS UP AND LIFTS OUT TUES NIGHT AND EARLY WEDNESDAY WITH SOME LIFT RETURNING TO THE NORTH TEXAS. AT THIS TIME...WE FEEL MOISTURE WILL BE TOO LIMITED FOR PRECIPITATION BUT WILL MONITOR CLOSELY. WE CONTINUE TO UNDERCUT MOS HIGH TEMPERATURES SINCE THE COLD AIRMASS IS 5-7 KFT DEEP WITH ONLY A SLOW MODIFICATION BY THURSDAY. NEXT COLD FRONT IS EXPECTED TO ARRIVE FRIDAY...AS ANOTHER SHORTWAVE DISTURBANCE MOVES SOUTHEAST ACROSS THE FRONT RANGE OF THE ROCKIES. GFS IS THE FASTEST WITH THE COLD FRONT...WHILE THE SREF/CANADIAN/AND ARE ECMWF SLOWER. FOR NOW...WILL LEAN TOWARD A SLOW CONSENSUS ON THE FRONT WITH WARMER TEMPERATURES FRIDAY THAN WHAT THE MAV MOS GUIDANCE. WE WILL ALSO LEAVE THIS PERIOD DRY WITH UNCERTAINTIES ON MOISTURE AVAILABILITY AND TIMING OF BOTH SURFACE AND UPPER LEVEL FEATURES. 05/42 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 41 45 38 40 29 / 80 100 90 60 20 WACO, TX 48 49 39 44 30 / 70 100 90 60 20 PARIS, TX 49 50 38 44 29 / 100 100 80 70 20 DENTON, TX 38 42 37 38 27 / 70 100 80 60 20 MCKINNEY, TX 42 45 37 41 29 / 100 100 80 60 20 DALLAS, TX 43 47 38 41 30 / 90 100 90 60 20 TERRELL, TX 49 49 39 44 30 / 100 100 90 70 20 CORSICANA, TX 52 52 40 45 31 / 70 100 90 70 20 TEMPLE, TX 54 54 40 46 30 / 80 100 90 60 20 MINERAL WELLS, TX 37 41 34 36 26 / 40 90 70 60 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
325 AM CST SUN DEC 4 2011 .SHORT TERM...TODAY THROUGH TUESDAY NIGHT 324 AM CST SUN DEC 4 2011 MAIN FORECAST CONCERN NOW THAT THE PRECIPITATION IS EXITING/DIMINISHING IS WHEN CLOUDS WILL CLEAR. CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING STILL OVER THE EAST PACIFIC AND ALONG THE EAST COAST OF THE U.S....AND TROUGHING IN-BETWEEN FROM HUDSON BAY SOUTHWEST INTO ARIZONA. IMPORTANT FEATURES TO NOTE INCLUDE A SHORTWAVE NEAR EAU CLAIRE WI ON THE EAST SIDE OF THE UPPER TROUGH...AND TWO SHORTWAVES OVER MONTANA ON THE BACK SIDE OF THE UPPER TROUGH. THE FORMER SHORTWAVE IN CONJUNCTION WITH PLENTIFUL MOISTURE AND LOW TO MID-LEVEL FRONTOGENESIS BROUGHT THE WIDESPREAD PRECIPITATION TO THE AREA LAST NIGHT. DRY SLOT NOTED IN WATER VAPOR COMBINED NOW WITH THE SHORTWAVE MOVED THROUGH...RESULTING IN SOME SUBSIDENCE...HAS ALLOWED PRECIPITATION TO REALLY DIMINISH DURING THE PAST 4-6 HOURS. IT APPEARS MODELS YESTERDAY MAY HAVE OVERDONE THE LOW LEVEL ISENTROPIC LIFT FOR THE CURRENT EARLY MORNING HOURS... GIVEN THAT THEY NOW SHOW NO ISENTROPIC LIFT AND SEEING THE PRECIPITATION DIMINISH ON RADAR. THEREFORE...THE CONCERN ABOUT THE DRY SLOT CLEARING OUT ICE AND RESULTING IN FREEZING PRECIPITATION IS NOT AS GREAT. IN ADDITION... SURFACE TEMPERATURES HAVE STRUGGLED TO FALL BELOW FREEZING WHERE IR CLOUD TOP TEMPERATURES INDICATE ICE HAS BEEN LOST. REGARDING THE SURFACE...SEA LEVEL PRESSURE ANALYSIS SHOWS A 1008MB LOW NEAR MANITOWIC WI. PLENTY OF CLOUDS EXTEND WEST FROM THE LOW...BACK INTO THE EASTERN DAKOTAS. UPSTREAM...ANOTHER BUT MUCH WEAKER SURFACE LOW IS NOTED NEAR WILLISTON ASSOCIATED WITH ONE OF THE MONTANA SHORTWAVES. TODAY AND TONIGHT...A SHORTWAVE IN EASTERN MONTANA IS PROGGED TO MOVE INTO SOUTH DAKOTA TODAY AND INTO NORTHWEST WISCONSIN TONIGHT. THE TRACK OF THE SHORTWAVE SUGGESTS ALL OF THE FORCING WILL STAY NORTH AND WEST OF THE AREA. THIS IS CONFIRMED TOO BY QG PLOTS. IN ADDITION...IT APPEARS MUCH OF THE CLOUD COVER ASSOCIATED WITH THE SHORTWAVE WILL STAY TO THE NORTHWEST. SO THIS LEAVES THE CURRENT CLOUD COVER AND SYSTEM GOING THROUGH THE MAIN CONCERN. WITH STRATUS EXTENDING SO FAR WEST...GRADUAL SUBSIDENCE OCCURRING TODAY IN THE WAKE OF THE SYSTEM AND THE LOW SUN ANGLE...THINKING A VERY PESSIMISTIC TREND MIGHT BE THE WAY TO GO. LIKE THE 04.00Z NAM INDICATING THE STRATUS STAYS IN PUT ACROSS THE AREA TODAY WITH ONLY SLOW CLEARING TONIGHT FOR WESTERN AREAS. CONCERNED THAT EVEN THE NAM MIGHT BE TOO FAST TONIGHT AS THE 900-950MB WINDS TURN FROM THE NORTHWEST TO NORTH. COMBINED WITH THE RECENT MOISTURE...CLOUDS MAY ACTUALLY LOWER IN CEILING HEIGHT VERSUS CLEARING. LAST CONCERN IS PRECIPITATION...BOTH THIS MORNING AND POSSIBLY OUT OF THE STRATUS DECK TONIGHT. GIVEN DIMINISHING RADAR RETURNS AND DRY FORECASTS INDICATED BY THE 04.00Z NAM/GFS/ECMWF FOR 12-18Z TODAY...HAVE REALLY DRIED OUT THIS MORNING. IN FACT...THERE MAY NOT BE MUCH GOING ON AFTER 12Z. WITH PRECIPITATION RAPIDLY DIMINISHING...WILL CANCEL THE ADVISORY HERE AT 4 AM. TONIGHT...THE 04.00Z NAM/GFS SHOW SOME LIGHT QPF OVER THE NORTH HALF OF WISCONSIN. APPEARS TO RESULT FROM LOW LEVEL CONVERGENCE...ASSOCIATED WITH SURFACE TROUGHING LINGERING BACK FROM THE CURRENT AREA OF LOW PRESSURE NEAR GRB. HAVE ADDED A 20 PERCENT CHANCE OF SNOW INTO THE FORECAST TO ACCOUNT FOR THIS POSSIBILITY. OTHERWISE...TEMPERATURES LOOK LIKE THEY SHOULD STRUGGLE TO RISE TODAY WITH 850MB TEMPS FALLING TO AT LEAST -6 TO -8C AND CLOUDS STAYING PUT. MAYBE A 1 OR 3 DEGREE F RISE IS POSSIBLE FROM THE 6 AM TEMPERATURE. WITH MORE CLOUDS ANTICIPATED TONIGHT...BROUGHT LOW TEMPERATURES UP A FEW DEGREES...ESPECIALLY ALONG AND EAST OF THE MISSISSIPPI RIVER WHERE CLOUDS ARE MORE CERTAIN. WHERE CLOUDS CLEAR OUT...TEMPERATURES COULD FALL INTO THE UPPER SINGLE DIGITS. MONDAY THROUGH TUESDAY NIGHT...BIG STORY/CONCERN HERE IS FORECASTING WHEN THE STRATUS WILL DISSIPATE AND ANY POTENTIAL PRECIPITATION OUT OF IT. UPPER TROUGH SITUATED OVER THE NORTHERN PLAINS IS FORECAST TO MARCH SOUTHEAST DURING THIS PERIOD...IN RESPONSE TO A POWERFUL UPPER TROUGH DIGGING FORMING OVER CENTRAL CANADA. NORTH TO NORTHEAST LOW LEVEL FLOW IS LIKELY MONDAY INTO MONDAY NIGHT WITH HIGH PRESSURE BUILDING INTO THE NORTHERN PLAINS. THIS FLOW SHOULD DO A DECENT JOB IN HOLDING IN THE STRATUS BELOW THE SUBSIDENCE INVERSION...UNTIL MAYBE LATE MONDAY NIGHT WHEN THERE IS SUGGESTION THE FLOW BACKS NORTHWEST TO BRING IN SOME DRIER LOW LEVEL AIR. IN ADDITION...THAT TROUGH MENTIONED IN THE TONIGHT DISCUSSION IS PROGGED TO DROP SOUTHWEST DUE TO THE LOW LEVEL FLOW. CONVERGENCE ALONG THIS TROUGH COULD RESULT IN SOME FLURRY ACTIVITY AND HAVE ADDED IT TO THE FORECAST. 04.00Z CANADIAN MODEL IS EVEN MORE AGGRESSIVE AND SHOWING A FEW HUNDREDTHS. IF OTHER MODELS...SUCH AS THE NAM/GFS START TO SHOW THIS IN LATER RUNS...MAY NEED TO HAVE SOME HIGHER CHANCES ADDED. BETTER POTENTIAL FOR CLEARING EXISTS TUESDAY AS THE SURFACE RIDGE MOVES IN AT THE SAME TIME WITH DAYTIME HEATING...SO INDICATED CLEARING STARTING HERE. UPPER RIDGING THEN BUILDS OVER THE AREA FOR TUESDAY NIGHT AHEAD OF THE POWERFUL UPPER TROUGH...MAINTAINING DRY CONDITIONS WITH GENERALLY MOSTLY CLEAR SKIES. FOR TEMPERATURES... LOOK FOR A COOLING TREND AS THE UPPER TROUGH MOVES IN. DID RAISE LOW TEMPERATURES UP MONDAY NIGHT IN THE CLOUDY SKY AREA...CLOSER TO THE 2 METER NAM12 GUIDANCE. OTHERWISE...A BLEND OF GUIDANCE SEEMED REASONABLE. .LONG TERM...WEDNESDAY THROUGH SATURDAY NIGHT 324 AM CST SUN DEC 4 2011 AFTER WHAT WAS SOME UNCERTAINTY IN THE LONG TERM FORECAST...CAUSED ESPECIALLY BY THE 03.12Z ECMWF SUGGESTING A POSSIBLE ADVISORY-TYPE SNOW MOVING THROUGH FRIDAY/FRIDAY NIGHT...ALL MODELS HAVE COME BACK INTO GREAT AGREEMENT ON THE UPPER AND SURFACE PATTERNS THROUGHOUT THE LONG TERM. IN FACT...THEY LOOK A LOT LIKE WHAT WAS SHOWN BY THE 03.00Z CYCLE. SO FOR NOW WILL CONSIDER THE 03.12Z ECMWF AN ODD OUTLIER. A WEST-NORTHWEST FLOW UPPER PATTERN BEGINS THE LONG TERM...ON THE SOUTH SIDE OF THE POWERFUL TROUGH DROPPING INTO SOUTHERN CANADA. A COLD FRONT LOOKS TO SLIDE THROUGH THE FORECAST AREA ON WEDNESDAY...ENDING A BRIEF WARM SURGE ALOFT CAUSED BY THE UPPER RIDGE. THEN FOR WEDNESDAY NIGHT AND THURSDAY...A SHORTWAVE TROUGH IS FORECAST TO DIG DOWN THE WEST SIDE OF THE CANADA UPPER TROUGH...CAUSING AN UPPER JET TO STRENGTHEN DOWNSTREAM OVER NORTHERN WISCONSIN. RIGHT ENTRANCE REGION FORCING OF THIS JET SHOULD INDUCE SOME MID-LEVEL FRONTOGENESIS...AND COMBINED WITH A LITTLE MOISTURE MAY PRODUCE A BAND OF LIGHT SNOW OVER FAR SOUTHERN SECTION THURSDAY NIGHT. INCLUDED A 20 PERCENT CHANCE FOR THIS. BIGGER IMPACT IS ON FRIDAY WHEN THE SHORTWAVE TROUGH MOVES ACROSS...CAUSING 850MB TEMPS TO TANK FROM -9 TO -13C ON THURSDAY TO AROUND -20C ON FRIDAY. NEEDLESS TO SAY...BELOW NORMAL TEMPERATURES LIKELY. A DRY AND SLOW WARMING TREND SHOULD THEN ENSUE HEADING INTO THE WEEKEND IN RESPONSE TO THE MODELS FORECASTING THE UPPER FLOW BECOMING MORE ZONAL. IN FACT...THE LATEST 04.00Z ECMWF SUGGESTS HIGHS APPROACHING 40 FOR NEXT SUNDAY AS A SURGE OF DOWNSLOPED WARMED PACIFIC AIR FLOWS INTO THE AREA. && .AVIATION...THROUGH 18Z SUNDAY 1130 PM CST SAT DEC 3 2011 SNOW WILL CONTINUE TO DIMINISH OVERNIGHT AS THE STORM SYSTEM PULLS NORTHEAST. VSBYS SHOULD HOLD IN THE 3-5SM WITH -SN OR BR FOR MUCH OF SUNDAY MORNING THOUGH. -FZDZ DOESN/T LOOK LIKE A CONCERN FOR KRST/KLSE NOW AS SATELLITE TRENDS AND RH FIELDS SUGGEST THE DRIER MID LEVELS WOULD STAY SOUTH OF THE TAF SITES...AND THUS KEEP THE ICE FREE CLOUDS - AND POTENTIAL FZDZ MAKERS - SOUTH. STILL...SOMETHING TO MONITOR. CIGS WILL BE A BIGGER CONCERN AS THE LOW LEVEL MOISTURE REMAINS ENTRENCHED ACROSS THE AREA. 00Z NAM NOW MORE SUGGESTIVE OF HANGING ONTO MVFR/IFR CONDITIONS FOR MUCH OF TODAY INTO TONIGHT. SOME HINTS OF A BRIEF BREAK INTO SCT SUN NIGHT...BUT CONFIDENCE ISN/T HIGH ENOUGH AND WILL HOLD WITH CIGS THROUGH 06Z MON. && .ARX WATCHES/WARNINGS/ADVISORIES... 324 AM CST SUN DEC 4 2011 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION..... RIECK
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1037 PM CST SAT DEC 3 2011 UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE .UPDATED...CONCERNING HEADLINES. AVAILABLE REPORTS IN THE ADVISORY AREA SO FAR THIS EVENING RANGE UP TO 2 INCHES. IR LOOP SHOWS BEST ENHANCEMENT HAS QUICKLY SHIFTED NORTHEASTWARD INTO UPPER MICHIGAN. RADAR AND OBS ACROSS THE REGION INDICATE THE RAIN SNOW LINE EXTENDS FROM NORTHWEST IOWA TO RST TO STE TO JUST SOUTH OF IMT. A SURFACE LOW WAS OVER SOUTHERN IOWA EARLY THIS EVENING AND WILL BE ENTERING SOUTHWEST WISCONSIN LATE THIS EVENING AND NEARLY TRACKING ALONG THE RAIN SNOW LINE OVERNIGHT. A LARGE AREA OF RAIN WAS IN THE WARM SECTOR OF THE LOW OVER IOWA AND SOUTHERN WISCONSIN MOVING TOWARD EASTERN WISCONSIN. PARTS OF EASTERN WISCONSIN MAY SEE UP TO AN ADDITIONAL INCH OF RAIN OVERNIGHT. BUT BACK TO THE ADVISORY...BEST SNOW GROWTH REGION WAS OVER NORTHWEST WISCONSIN AND MAY INCLUDE WESTERN PORTIONS OF ONEIDA AND VILAS COUNTIES. THIS SNOW GROWTH REGION IS PROGGED TO SAG INTO NORTH CENTRAL WISCONSIN OVERNIGHT AS THE H8 LOW AND SURFACE LOW TRACKS OVER. NOT OUT OF THE QUESTION A WARNING MAY BE NEEDED AS THESE MORE FAVORABLE DYNAMICS PLAY A ROLE...BUT FOR NOW WILL CONTINUE THE HIGH END ADVISORY. TDH && .PREV DISCUSSION...ISSUED AT 505 PM CST SAT DEC 3 2011... SHORT TERM...TONIGHT AND SUNDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A DEVELOPING LOW PRESSURE SYSTEM MOVING NORTHEAST OVER SOUTH-CENTRAL KANSAS JUST AHEAD OF A SHORTWAVE TROUGH. ATTACHED TO THE SURFACE LOW TO THE NORTHEAST RUNS A COLD FRONT OVER CENTRAL IOWA INTO NORTHWEST WISCONSIN. FIRST BATCH OF PRECIP IS RIDING ALONG THE 850MB BAROCLINIC ZONE OVER THE SOUTHEASTERN HALF OF WISCONSIN THOUGH SOME BREAKS ARE SPREADING OVER EASTERN IOWA AND NORTHERN ILLINOIS...THAT MAY SPELL A BREAK IN THE PRECIP FOR A BRIEF PERIOD LATE THIS AFTERNOON OVER E-C WISCONSIN. THE MAIN AXIS OF PRECIP...HOWEVER... EXISTS JUST TO THE EAST OF THE SURFACE LOW ON THE NOSE OF A 60 KT LLJ AND UPPER DIVERGENT AREA WITHIN THE COUPLED JET. SOME HIGHER REFLECTIVITIES ARE ALSO DEVELOPING OVER WESTERN WISCONSIN WITHIN A STRENGTHENING FGEN ZONE...SO WILL JUST START THE WINTER HEADLINES WITH THE AFTERNOON PACKAGE. AS THE LOW TRACKS NORTHEAST OVER THE NEXT 24 HOURS...THE OBVIOUS CONCERNS ARE SNOW AMOUNTS AND HEADLINES. TONIGHT...FOLLOWED A SREF/GFS BLEND TONIGHT...WHICH SPLITS THE DIFFERENCE BETWEEN THE STRONGER NAM AND WEAKER ECMWF WHILE KEEPING THE CONSENSUS TRACK. LOW PRESSURE OVER THE CENTRAL PLAINS WILL RAPIDLY MOVE NE TOWARDS THE MID-MISSISSIPPI VALLEY THIS EVENING...AND NORTHERN LAKE MICHIGAN BY 12Z SUNDAY. AHEAD OF THE LOW...A BEEFY LLJ WILL SHIFT INTO SOUTHERN WISCONSIN THIS EVENING...THEREBY INCREASING CONVERGENCE ALONG THE STALLED BAROCLINIC ZONE STRETCHING ACROSS THE STATE...AND 850-700MB FGEN IN THE PROCESS. COMBINED WITH STRONG QG FORCING FROM SHORTWAVE ENERGY AND A WIDE OPEN GULF (PWATS 150-200 PCT OF NORMAL)...THE BEEFY SLUG OF PRECIP OVER THE PLAINS WILL HAVE NO TROUBLE SPREADING ACROSS THE STATE THIS EVENING. PTYPE REMAINS PROBLEMATIC AS THE 12Z MODEL RUNS HAVE TRENDED SLIGHTLY WARMER WITH THE THERMAL PROFILE AS THE LOW PUSHES WARMER AIR ALOFT SLIGHTLY FARTHER NORTH THAN PREVIOUS RUNS. THIS WILL PLACE THE RAIN-SNOW MIX AREA FROM WOOD COUNTY TO NORTHERN OCONTO AND MARINETTE. NORTH OF THE RAIN-SNOW LINE SHOULD RESIDE THE AXIS OF HEAVIEST SNOWFALL...WHICH LINES UP WITH THE EXTRAPOLATED SOUTHERN EDGE OF THE COMMA HEAD FROM APPROX MERRILL TO CRANDON. WITH SLIGHTLY COLDER AIR IN PLACE COMPARED TO THE FIRST SNOW STORM IN NOVEMBER...SNOW RATIOS WILL RUN BETWEEN 10-14:1 OVER THIS AREA ACCORDING TO THE COBB SNOWFALL ALGORITHM. WITH QPFS AROUND 0.4 TO 0.5 INCHES...THIS AMOUNTS TO A GOOD 4-6 INCH SWATH OF SNOW TONIGHT (5 TO 7 INCHES OVERALL)...THOUGH THE BULK OF THE PRECIP WILL LIKELY FALL THIS EVENING. THE FOX VALLEY AND LAKESHORE WILL RESIDE WITHIN THE WARM SECTOR OF THE STORM...WHICH MEANS MOSTLY RAIN TONIGHT...THOUGH SOME SNOW MAY MIX IN LATE. ENTERTAINED SOME THOUGHTS OF UPGRADING TO A WARNING GIVEN THE HEAVY SNOW OBS UPSTREAM...BUT GIVEN THE RELATIVELY LOW IMPACT OF THE SNOW (DURING THE NIGHT ON A WEEKEND)...WILL STICK WITH ADVISORY HEADLINES. ALSO THOUGHT ABOUT TRIMMING THE ADVISORY TO THE NW BY A ROW OF COUNTIES...BUT COORDINATION WITH SURROUNDING OFFICES YIELDED A RELUCTANCE...DUE TO THE SLOPPINESS OF THE MIX AND POTENTIAL FOR FREEZING DRIZZLE. AS A RESULT...WILL KEEP CURRENT HEADLINES AS THEY CURRENTLY STAND BUT STRESS THE HEAVY SNOWFALL RATES ARRIVING THIS EVENING. SUNDAY...THE LOW PRESSURE WILL QUICKLY EXIT TO SOUTHEAST ONTARIO BY 18Z SUNDAY BUT WILL HAVE THE BACK EDGE OF THE COMMA HEAD SHIFTING NE OVER N-C AND FAR NORTHEAST WISCONSIN. SOME MID-LEVEL FGEN WILL LINGER WHICH WILL RESULT IN ANOTHER HALF INCH TO AN INCH OVER N-C WISCONSIN EARLY IN THE MORNING. BUT OTHERWISE...SNOW WILL BE TAPERING DOWN TO JUST FLURRIES IN THE MORNING...WHILE COLDER AIR FILTERS ACROSS THE REGION. LOW LEVEL TROUGHINESS AND CYCLONIC FLOW WILL HANG AROUND FOR MUCH OF THE DAY...SO NOT ANTICIPATING MUCH CLEARING TOMORROW. HIGHS MAINLY IN THE LOW TO MIDDLE 30S. LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY...THE MAIN FCST CONCERNS WILL BE MINOR LAKE EFFECT SNOW POTENTIAL OVER NORTHERN WI EARLY IN THE PERIOD...THEN THE POTENTIAL FOR SNOW AND MUCH COLDER TEMPERATURES WITH AN ARCTIC FRONTAL PASSAGE LATE NEXT WEEK. A STRONG...HIGH AMPLITUDE RIDGE WILL COVER THE EASTERN PACIFIC... WESTERN CANADA AND THE WEST COAST OF THE U.S. EARLY IN THE PERIOD... WITH A POSITIVELY-TILTED UPPER TROF EXTENDING FROM CENTRAL CANADA INTO THE SOUTHWEST UNITED STATES. THIS UPPER TROF WILL MOVE THROUGH WISCONSIN ON TUESDAY...WITH LITTLE IMPACT ON OUR WEATHER. SHORT-WAVE ENERGY WILL TOP THE WESTERN RIDGE EARLY NEXT WEEK...THEN EVENTUALLY HELP TO CARVE A BROAD TROF OVER THE CENTRAL U.S. BY THU/FRI. A SURGE OF ARCTIC AIR IS EXPECTED TO ARRIVE IN WI LATE IN THE WEEK... WITH H8 TEMPS PLUMMETING TO AROUND -20 C. THIS WILL LEAD TO OUR COLDEST TEMPERATURES SO FAR THIS SEASON. A LARGE RIDGE OF HIGH PRESSURE WILL BE CENTERED OVER THE NORTHERN ROCKIES AND NORTHERN PLAINS SUN NGT INTO MON...WITH COLD NORTH FLOW RESULTING IN SCT LAKE-EFFECT SNOW SHOWERS OVER MAINLY NC WI. THE SNOW SHOWERS MAY LINGER INTO MONDAY NIGHT...BUT SHOULD COME TO AN END ON TUESDAY AS THE RIDGE AXIS PUSHES ACROSS WI. A WEAK COLD FRONT IS EXPECTED TO MOVE THROUGH THE REGION ON WEDNESDAY...WITH A STRONGER ARCTIC FRONT ARRIVING SOMETIME DURING THE THU/FRI TIME FRAME. DURING THIS PERIOD...LLVL FLOW IS EXPECTED TO BE TOO WESTERLY FOR LK-EFFECT. THE ECMWF AND A FEW OF THE GFS ENSEMBLE MEMBERS SUGGEST THAT A SFC WAVE WILL DEVELOP ALONG THE ARCTIC BOUNDARY LATE IN THE WEEK...AS THE RRQ OF A STRONG UPPER LEVEL JET PULLS THROUGH THE REGION. IF THIS PLAYS OUT...WE COULD BRING SEE SEVERAL INCHES OF POWDERY SNOW SOMETIME DURING THE THURSDAY NIGHT TO SATURDAY PERIOD. FOR NOW...WILL FOLLOW THE CONCENSUS OF AREA OFFICES...AND JUST MENTION SMALL POPS ACROSS OUR SOUTHERN AND EASTERN COUNTIES ON THU NGT/FRI. THERE IS A HIGHER DEGREE OF CONFIDENCE IN A TREND TOWARD MUCH COLDER TEMPERATURES LATE IN THE WEEK...ALTHOUGH THE NEW ECMWF IS SLOWER WITH THE TIMING OF THE ARCTIC BOUNDARY. SUBSEQUENT FCSTS SHOULD BE BETTER ABLE TO PINPOINT THE FRONTAL TIMING AND SNOWFALL POTENTIAL LATE NEXT WEEK. && .AVIATION...IFR TO LIFR CIGS AND VSBYS WILL CONTINUE OVER CENTRAL AND NORTH CENTRAL WISCONSIN AS STEADY SNOWS CONTINUE TO AFFECT THE AREA OVERNIGHT. MAINLY LIFR TO IFR CIGS WITH IFR VSBYS WITH RAIN AND FOG TO IMPACT EASTERN WISCONSIN. PERSISTENT RAIN/SNOW LINE CONTINUES TO RUN FROM AROUND ISW TO JUST SOUTH OF IMT LATE THIS EVENING. CIGS AND VSBYS TO GRADUALLY IMPROVE TO MVFR CONDITIONS SUNDAY AS THE LOW PRESSURE SYSTEM DEPARTS TO THE NORTHEAST. TDH && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR WIZ005-010>013- 018-019-021-030-035. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
912 AM CST SUN DEC 4 2011 .DISCUSSION... 340 AM CST HIGHLIGHTS THIS WEEK WILL INCLUDE RAIN COMING TO AN END...POSSIBLE SN/RASN/RA ACROSS THE SOUTHEAST MONDAY...LES POTENTIAL FOR LAKE/COOK LATE SUNDAY NIGHT INTO MONDAY...TRANSITIONING SOUTH TO LAKE/PORTER INDIANA BY TUESDAY...A FEW DAYS OF QUIET...FOLLOWED BY A LATE CLIPPER AND SNOW POTENTIAL AND FINALLY A BLAST OF COLD BY NEXT WEEKEND. THE EARLY MORNING SURFACE MAP SHOWED THE SURFACE LOW THAT HAS BEEN BRINGING THE WET AND ACTIVE WEATHER TO THE AREA TODAY...CONTINUING TO LIFTING NORTH THROUGH CENTRAL WISCONSIN. MEANWHILE AN ATTENDANT COLD FRONT LAY ROUGHLY ACROSS THE MISSISSIPPI RIVER...SOUTHWEST NEARLY TO ST LOUIS. THIS FRONT WILL CONTINUE TO SLOWLY SWEEP FROM WEST TO EAST THIS MORNING EVENTUALLY PUSHING ITSELF AND THE PRECIP EAST. THE MOST WIDE SPREAD ECHOES HAVE PUSHED EAST AND ONLY A FEW SCATTERED SHOWERS ARE LOCATED WITH THE ACTUAL FRONT. ACROSS EAST CENTRAL IOWA...TEMPERATURES HAVE DROPPED ENOUGH THAT -SN WAS REPORTED...BUT CLOUD TOPS HAVE WARMED ENOUGH AND ARE WARMER THAN -10C. THIS MEANS THAT THERE IS NO LONGER ICE INTRODUCTION INTO THE SATURATED LAYERS BELOW...AND A FEW LOCATIONS REPORTED U.P. AND OR FZDZ. FOR OUR AREA...AFTER THE FRONT MOVES THROUGH...LOWER LEVEL MOISTURE WILL REMAIN BUT PROFILES ARE STILL INDICATIVE OF LIQUID PRECIP AND SURFACE TEMPS WILL REMAIN ABOVE FREEZING. THE HRRR AND RUC BOTH HAVE A GOOD HANDLE ON THE WESTERN EDGE OF THE PRECIP AND FRONTAL LOCATION...AND MOST OF IT SHOULD CLEAR THE ROCKFORD CORRIDOR NEAR SUNRISE...WITH CHICAGO AND EAST JUST A FEW HOURS BEYOND. WHILE LOWER LEVEL RH WILL REMAIN PREVALENT WITH AND SHORTLY BEYOND FROPA...MOISTURE ABOVE -10C WILL DISAPPEAR AND THERE MAY BE SOME LINGERING DZ INTO THE EARLY MORNING HOURS. THE BIG PUSH OF COLDER AIR ISNT EXPECTED UNTIL LATER THIS EVENING AND TEMPERATURES WILL REMAIN ABOVE FREEZING...SO NO CONCERN OVER ANY OTHER PRECIP TYPES THIS MORNING. HIGH TEMPS WILL GENERALLY BE SEEN EARLY TODAY...AND SLOWLY FALL THROUGH THE DAY. WINDS WILL ABATE AS HIGH PRESSURE AND A PERIOD OF DRY...SLOWLY MOVE IN. THE MAIN UPPER LEVEL TROUGHING THAT STRETCHES FROM ROUGHLY SASKATCHEWAN...SOUTHWEST THROUGH THE FOUR CORNERS REGION WILL NOT HAVE MUCH REASON TO MOVE UNTIL THE START OF THE WORKWEEK. PRESENT SHORTWAVE SEEN ON WATER VAPOR IMAGERY ROUNDING THE BASE OF THE TROUGH...ACROSS SOUTHERN ARIZONA...WILL DAMPEN SOME AS IT GETS EJECTED ON THE EASTERN FLANK TODAY AND TONIGHT. AS IT DOES THIS...IT WILL HELP TO AMPLIFY AN INVERTED TROUGH THAT WILL NOSE ITS WAY TOWARDS THE OHIO VALLEY...EVENTUALLY SPAWNING A WEAK LOW ACROSS THE TENNESSEE VALLEY. GUIDANCE HAS BEEN HEMMING AND HAWING WITH JUST HOW FAR NORTH TO BRING THE PRECIP WITH THIS FEATURE...AND JUST HOW MUCH OF IT WILL REACH INTO THE SOUTHEASTERN CORNER OF THE CWA. THE LATEST FORECAST TRENDS HAVE BACKED OFF FROM PREVIOUS...AND DID SCALE BACK ON POPS AS WELL AS COVERAGE. STILL A LITTLE UNCERTAIN WITH WHERE THE RASN VS STRAIGHT RA LINE WOULD BE AND WILL MAINTAIN A SORT OF MIX. ALSO OF NOTE FOR COASTAL LOCATIONS IN THIS SAME TIME FRAME /AS THE INV TROF-LOW SLIDE EAST/ IS THE CHANCE FOR LES. THERMAL PROFILES ACROSS THE SOUTHERN LAKE WILL BECOME INCREASINGLY UNSTABLE WITH LAKE SURFACE TO H85 DELTA T`S REACHING THE 12-15C RANGE. EXPECT WEAK SHOWERS TO BEGIN TO STRETCH FROM LAKE COUNTY IL...EVENTUALLY SOUTH TO COOK AND GRADUALLY INTO THE MORE TYPICAL LAKE/PORTER IN ORIENTATION. QPF AMOUNTS NOT LOOKING VERY IMPRESSIVE DURING THE SHORT DURATION AND WOULD ONLY EXPECT ANYWHERE FROM A TRACE TO MAYBE A TENTH OR TWO OF ACCUMULATION CLOSE TO THE LAKE TOMORROW AND INTO TOMORROW NIGHT. THIS WILL ALL BE FOLLOWED BY A FEW DAYS OF QUIET AS ANOTHER RIDGE OF HIGH PRESSURE SWINGS IN FROM THE NORTHWEST. A LATE WEEK SYSTEM IS STILL PART OF A LOW CONFIDENCE FORECAST. GFS HAD BEEN ADVERTISING A WEAK CLIPPER DROPPING FROM THE NORTHERN PLAINS... AND PREVIOUS EC SOLNS HAD SIMILAR...BUT THE 12Z FLIPPED AND DEVELOPED A SURFACE LOW THAT LIFTS THROUGH THE MISSISSIPPI VALLEY...INTO NORTHERN INDIANA...NORTHEAST THROUGH EASTERN ONTARIO. CONFIDENCE AT THIS POINT ON THAT EURO SOLN IS LOW AND WILL KEEP THE CHANCE OF SNOW AND NOT BUMP UP (OR DOWN) ANY CATEGORY UNTIL THE PICTURE IS A LITTLE CLEARER. THE 00Z SOLN BEGAN TO COME IN AND WAS BACK TO THE ORIGINAL PICTURE WITH THE CLIPPER RACING THROUGH. DESPITE THE LOWER CONFIDENCE IN THAT FEATURE LATE THIS WEEK...THE ONE PICTURE OF CLARITY WHAT WILL FOLLOW IT. ALL LONG RANGE GUIDANCE IS STILL INDICATING THAT THERE WILL BE A LARGE SURGE OF COLD AIR ENCROACHING AS AN UPPER LEVEL TROUGH SWINGS THROUGH. THERE ARE STILL SOME TIMING DIFFERENCES WITH HOW QUICKLY THE COLD AIR WILL DUMP IN...WHICH IS DUE IN PART TO THE LARGE MODEL DIFFERENCES MENTIONED MOMENTS AGO...BUT THE ONE THING THEY ALL AGREE ON IS HOW COLD THE LOWER LEVELS WILL GET INTO THE WEEKEND. EVEN A WEEK OUT...THE EC/GFS/GEFS/DGEX/GEM(NHEM THROUGH F144) ALL HIGHLIGHT H85 TEMPS PLUMMETING TO -16 TO -18 DEGREES...OR EVEN A FEW DEGREES COLDER. TRANSLATE THAT TO THE SURFACE AND IT WOULD BE POSSIBLE THAT HIGHS WOULD STRUGGLE TO GET OUT OF THE TEENS FOR MANY LOCATIONS AND OVERNIGHT LOWS LEADING INTO THE WEEKEND WOULD DIVE BOMB TO THE SINGLE DIGITS /BUT LIKELY A SMIDGEN WARMER IN THE CHICAGO METRO/. WITH THAT FORECAST STILL BEING OUT 6-7 DAYS...AND A SLEW OF OTHER WEATHER GOING ON THROUGH THE EARLY WEEK... WILL ONLY CONTINUE TO TREND DOWN FROM THE INHERITED LONG RANGE FORECAST. THE BIG SAVING GRACE IS THE LACK OF SOLID SNOW PACK. IF THAT WERE PRESENT...IT WOULD BE MUCH COLDER. SHEA && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * LOW MVFR TO IFR POST FRONTAL CIGS MOVING BACK ACROSS THE TERMINALS LATER THIS MORNING. KJB //DISCUSSION...UPDATED 12Z... LOW PRESSURE OVER NORTHERN LAKE MICHIGAN MOVING QUICKLY NORTHEAST THIS MORNING. MOST OF THE RAIN HAS MOVED OUT OF THE AREA. ONLY A FEW LIGHT SHOWERS REMAIN ALONG THE COLD FRONT...WHICH STRETCHES FROM THE LOW TO JUST WEST OF RFD TO STL. JUST KEPT A VCSH IN FOR A FEW HOURS TO COVER A POSSIBLE BRIEF LIGHT SHOWER THROUGH MID MORNING. STRONG SSW WINDS STILL GUSTING TO AROUND 25 KTS EARLY THIS MORNING. WINDS WILL SHIFT WEST WITH COLD FRONTAL PASSAGE MID MORNING AND DIMINISH. MAY STILL SEE SOME GUSTS TO AROUND 20 KT OR SO THROUGH MIDDAY. WINDS WILL BECOME NORTHWEST AND FALL TO LESS THAN 10 KT BY LATE AFTERNOON. MAIN ISSUE TODAY WILL BE LOW CEILINGS...PRESENTLY RUNNING AROUND 1000-1500 FT. SOME IFR NOTED OVER IA AND WESTERN IL BEHIND THE COLD FRONT. BUT WITH EVERYTHING LIFTING NORTHEAST...AND LOOKING AT MODEL SOUNDINGS...DONT EXPECT IFR CIGS TO IMPACT THE CHICAGO AREA TERMINALS. RFD MY FLIRT WITH IFR THROUGH THE MORNING HOURS AND HAVE COVERED THIS WITH A TEMPO GROUP. SHOULD SEE AN IMPROVING TREND THROUGH THE AFTERNOON. THE BACK EDGE OF THE STRATUS OVER THE DAKOTAS...NEB...INTO NW MO IS PUSHING EAST ON SATELLITE IMAGERY. THERE IS A POSSIBILITY OF STRATUS SCATTERING OUT OVER NORTHERN IL TOWARDS EVENING OR OVERNIGHT...BUT CONFIDENCE IN THAT HAPPENING IS LOW AND WILL HANG ON TO MVFR CIGS THROUGH THE NIGHT AT THIS POINT. WINDS WILL GRADUALLY VEER NORTH NORTHEAST LATE TONIGHT INTO MONDAY MORNING. AS COLDER AIR MOVES DOWN THE LAKE...SOME LAKE EFFECT CLOUDS AND LIGHT SNOW SHOWERS ARE POSSIBLE MONDAY BUT AT THIS TIME IT APPEARS THE CLOUD DEPTH WILL BE TOO SHALLOW TO SUPPORT ANY SIGNIFICANT LAKE EFFECT FOR MONDAY. ALLSOPP //ORD AND MDW CONFIDENCE...UPDATED 14Z... * HIGH CONFIDENCE IN MVFR CIGS. * LOW CONFIDENCE IN CIGS DROPPING INTO THE IFR CATEGORY. KJB //OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z... MONDAY NIGHT...MVFR CIG. CHANCE LIGHT LAKE EFFECT SNOW SHOWERS. TUESDAY...VFR. WEDNESDAY...VFR. THURSDAY...VFR. FRIDAY...VFR. SATURDAY...VFR. ALLSOPP && .MARINE... 133 AM CST A POWERFUL STORM WAS MOVING THROUGH THE GREAT LAKES THIS MORNING. LOW PRESSURE WILL MOVE QUICKLY FROM WISCONSIN TO NORTHERN LAKE MICHIGAN THIS MORNING...THEN ON TO QUEBEC BY EVENING. EAST OF THE TRACK OF THE LOW A VERY STRONG SOUTHERLY LOW LEVEL JET WAS OCCURRING...WITH 50 KT WINDS JUST 1 TO 2 THOUSAND FEET OFF THE SURFACE. A STRONG INVERSION WAS LIMITING MIXING BUT GALE FORCE WINDS WERE WORKING DOWN TO THE LAKE SURFACE OVER THE SOUTH HALF WITH SOME GALE FORCE GUSTS ON THE EAST SIDE OF THE NORTH HALF OF THE LAKE. WINDS SHOULD DROP OFF PRETTY QUICKLY AS THE LOW MOVES RAPIDLY NORTHEAST TODAY AND GALES SHOULD END BY ABOUT NOON. PRESENTLY GALE WARNING GOES THROUGH MID AFTERNOON BUT IT MAY BE CANCELED EARLY. WINDS WILL VEER FROM SOUTH TO NORTHWEST THROUGH THE COURSE OF THE DAY. TONIGHT THROUGH MONDAY ANOTHER LOW WILL MOVE FROM THE TEXAS COAST UP THROUGH THE OHIO VALLEY WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. THIS WILL PRODUCE A PERIOD OF NORTHERLY WINDS ON LAKE MICHIGAN. THE REST OF THE WEEK HIGH PRESSURE WILL DOMINATE THE CENTRAL U.S. WHILE LOW PRESSURE BECOMES ANCHORED OVER NORTHEAST CANADA. THIS WILL PRODUCE A PROLONGED PERIOD OF WESTERLY WINDS OVER LAKE MICHIGAN FROM MID WEEK INTO THE WEEKEND. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 PM SUNDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
549 AM CST SUN DEC 4 2011 .DISCUSSION... 340 AM CST HIGHLIGHTS THIS WEEK WILL INCLUDE RAIN COMING TO AN END...POSSIBLE SN/RASN/RA ACROSS THE SOUTHEAST MONDAY...LES POTENTIAL FOR LAKE/COOK LATE SUNDAY NIGHT INTO MONDAY...TRANSITIONING SOUTH TO LAKE/PORTER INDIANA BY TUESDAY...A FEW DAYS OF QUIET...FOLLOWED BY A LATE CLIPPER AND SNOW POTENTIAL AND FINALLY A BLAST OF COLD BY NEXT WEEKEND. THE EARLY MORNING SURFACE MAP SHOWED THE SURFACE LOW THAT HAS BEEN BRINGING THE WET AND ACTIVE WEATHER TO THE AREA TODAY...CONTINUING TO LIFTING NORTH THROUGH CENTRAL WISCONSIN. MEANWHILE AN ATTENDANT COLD FRONT LAY ROUGHLY ACROSS THE MISSISSIPPI RIVER...SOUTHWEST NEARLY TO ST LOUIS. THIS FRONT WILL CONTINUE TO SLOWLY SWEEP FROM WEST TO EAST THIS MORNING EVENTUALLY PUSHING ITSELF AND THE PRECIP EAST. THE MOST WIDE SPREAD ECHOES HAVE PUSHED EAST AND ONLY A FEW SCATTERED SHOWERS ARE LOCATED WITH THE ACTUAL FRONT. ACROSS EAST CENTRAL IOWA...TEMPERATURES HAVE DROPPED ENOUGH THAT -SN WAS REPORTED...BUT CLOUD TOPS HAVE WARMED ENOUGH AND ARE WARMER THAN -10C. THIS MEANS THAT THERE IS NO LONGER ICE INTRODUCTION INTO THE SATURATED LAYERS BELOW...AND A FEW LOCATIONS REPORTED U.P. AND OR FZDZ. FOR OUR AREA...AFTER THE FRONT MOVES THROUGH...LOWER LEVEL MOISTURE WILL REMAIN BUT PROFILES ARE STILL INDICATIVE OF LIQUID PRECIP AND SURFACE TEMPS WILL REMAIN ABOVE FREEZING. THE HRRR AND RUC BOTH HAVE A GOOD HANDLE ON THE WESTERN EDGE OF THE PRECIP AND FRONTAL LOCATION...AND MOST OF IT SHOULD CLEAR THE ROCKFORD CORRIDOR NEAR SUNRISE...WITH CHICAGO AND EAST JUST A FEW HOURS BEYOND. WHILE LOWER LEVEL RH WILL REMAIN PREVALENT WITH AND SHORTLY BEYOND FROPA...MOISTURE ABOVE -10C WILL DISAPPEAR AND THERE MAY BE SOME LINGERING DZ INTO THE EARLY MORNING HOURS. THE BIG PUSH OF COLDER AIR ISNT EXPECTED UNTIL LATER THIS EVENING AND TEMPERATURES WILL REMAIN ABOVE FREEZING...SO NO CONCERN OVER ANY OTHER PRECIP TYPES THIS MORNING. HIGH TEMPS WILL GENERALLY BE SEEN EARLY TODAY...AND SLOWLY FALL THROUGH THE DAY. WINDS WILL ABATE AS HIGH PRESSURE AND A PERIOD OF DRY...SLOWLY MOVE IN. THE MAIN UPPER LEVEL TROUGHING THAT STRETCHES FROM ROUGHLY SASKATCHEWAN...SOUTHWEST THROUGH THE FOUR CORNERS REGION WILL NOT HAVE MUCH REASON TO MOVE UNTIL THE START OF THE WORKWEEK. PRESENT SHORTWAVE SEEN ON WATER VAPOR IMAGERY ROUNDING THE BASE OF THE TROUGH...ACROSS SOUTHERN ARIZONA...WILL DAMPEN SOME AS IT GETS EJECTED ON THE EASTERN FLANK TODAY AND TONIGHT. AS IT DOES THIS...IT WILL HELP TO AMPLIFY AN INVERTED TROUGH THAT WILL NOSE ITS WAY TOWARDS THE OHIO VALLEY...EVENTUALLY SPAWNING A WEAK LOW ACROSS THE TENNESSEE VALLEY. GUIDANCE HAS BEEN HEMMING AND HAWING WITH JUST HOW FAR NORTH TO BRING THE PRECIP WITH THIS FEATURE...AND JUST HOW MUCH OF IT WILL REACH INTO THE SOUTHEASTERN CORNER OF THE CWA. THE LATEST FORECAST TRENDS HAVE BACKED OFF FROM PREVIOUS...AND DID SCALE BACK ON POPS AS WELL AS COVERAGE. STILL A LITTLE UNCERTAIN WITH WHERE THE RASN VS STRAIGHT RA LINE WOULD BE AND WILL MAINTAIN A SORT OF MIX. ALSO OF NOTE FOR COASTAL LOCATIONS IN THIS SAME TIME FRAME /AS THE INV TROF-LOW SLIDE EAST/ IS THE CHANCE FOR LES. THERMAL PROFILES ACROSS THE SOUTHERN LAKE WILL BECOME INCREASINGLY UNSTABLE WITH LAKE SURFACE TO H85 DELTA T`S REACHING THE 12-15C RANGE. EXPECT WEAK SHOWERS TO BEGIN TO STRETCH FROM LAKE COUNTY IL...EVENTUALLY SOUTH TO COOK AND GRADUALLY INTO THE MORE TYPICAL LAKE/PORTER IN ORIENTATION. QPF AMOUNTS NOT LOOKING VERY IMPRESSIVE DURING THE SHORT DURATION AND WOULD ONLY EXPECT ANYWHERE FROM A TRACE TO MAYBE A TENTH OR TWO OF ACCUMULATION CLOSE TO THE LAKE TOMORROW AND INTO TOMORROW NIGHT. THIS WILL ALL BE FOLLOWED BY A FEW DAYS OF QUIET AS ANOTHER RIDGE OF HIGH PRESSURE SWINGS IN FROM THE NORTHWEST. A LATE WEEK SYSTEM IS STILL PART OF A LOW CONFIDENCE FORECAST. GFS HAD BEEN ADVERTISING A WEAK CLIPPER DROPPING FROM THE NORTHERN PLAINS... AND PREVIOUS EC SOLNS HAD SIMILAR...BUT THE 12Z FLIPPED AND DEVELOPED A SURFACE LOW THAT LIFTS THROUGH THE MISSISSIPPI VALLEY...INTO NORTHERN INDIANA...NORTHEAST THROUGH EASTERN ONTARIO. CONFIDENCE AT THIS POINT ON THAT EURO SOLN IS LOW AND WILL KEEP THE CHANCE OF SNOW AND NOT BUMP UP (OR DOWN) ANY CATEGORY UNTIL THE PICTURE IS A LITTLE CLEARER. THE 00Z SOLN BEGAN TO COME IN AND WAS BACK TO THE ORIGINAL PICTURE WITH THE CLIPPER RACING THROUGH. DESPITE THE LOWER CONFIDENCE IN THAT FEATURE LATE THIS WEEK...THE ONE PICTURE OF CLARITY WHAT WILL FOLLOW IT. ALL LONG RANGE GUIDANCE IS STILL INDICATING THAT THERE WILL BE A LARGE SURGE OF COLD AIR ENCROACHING AS AN UPPER LEVEL TROUGH SWINGS THROUGH. THERE ARE STILL SOME TIMING DIFFERENCES WITH HOW QUICKLY THE COLD AIR WILL DUMP IN...WHICH IS DUE IN PART TO THE LARGE MODEL DIFFERENCES MENTIONED MOMENTS AGO...BUT THE ONE THING THEY ALL AGREE ON IS HOW COLD THE LOWER LEVELS WILL GET INTO THE WEEKEND. EVEN A WEEK OUT...THE EC/GFS/GEFS/DGEX/GEM(NHEM THROUGH F144) ALL HIGHLIGHT H85 TEMPS PLUMMETING TO -16 TO -18 DEGREES...OR EVEN A FEW DEGREES COLDER. TRANSLATE THAT TO THE SURFACE AND IT WOULD BE POSSIBLE THAT HIGHS WOULD STRUGGLE TO GET OUT OF THE TEENS FOR MANY LOCATIONS AND OVERNIGHT LOWS LEADING INTO THE WEEKEND WOULD DIVE BOMB TO THE SINGLE DIGITS /BUT LIKELY A SMIDGEN WARMER IN THE CHICAGO METRO/. WITH THAT FORECAST STILL BEING OUT 6-7 DAYS...AND A SLEW OF OTHER WEATHER GOING ON THROUGH THE EARLY WEEK... WILL ONLY CONTINUE TO TREND DOWN FROM THE INHERITED LONG RANGE FORECAST. THE BIG SAVING GRACE IS THE LACK OF SOLID SNOW PACK. IF THAT WERE PRESENT...IT WOULD BE MUCH COLDER. SHEA && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 12Z... * MVFR CIGS. * STRONG GUSTY SSW WINDS VEERING WEST AND DIMINISHING BY AFTERNOON. * FEW LIGHT SHOWERS THROUGH ABOUT 15Z. ALLSOPP //DISCUSSION...UPDATED 12Z... LOW PRESSURE OVER NORTHERN LAKE MICHIGAN MOVING QUICKLY NORTHEAST THIS MORNING. MOST OF THE RAIN HAS MOVED OUT OF THE AREA. ONLY A FEW LIGHT SHOWERS REMAIN ALONG THE COLD FRONT...WHICH STRETCHES FROM THE LOW TO JUST WEST OF RFD TO STL. JUST KEPT A VCSH IN FOR A FEW HOURS TO COVER A POSSIBLE BRIEF LIGHT SHOWER THROUGH MID MORNING. STRONG SSW WINDS STILL GUSTING TO AROUND 25 KTS EARLY THIS MORNING. WINDS WILL SHIFT WEST WITH COLD FRONTAL PASSAGE MID MORNING AND DIMINISH. MAY STILL SEE SOME GUSTS TO AROUND 20 KT OR SO THROUGH MIDDAY. WINDS WILL BECOME NORTHWEST AND FALL TO LESS THAN 10 KT BY LATE AFTERNOON. MAIN ISSUE TODAY WILL BE LOW CEILINGS...PRESENTLY RUNNING AROUND 1000-1500 FT. SOME IFR NOTED OVER IA AND WESTERN IL BEHIND THE COLD FRONT. BUT WITH EVERYTHING LIFTING NORTHEAST...AND LOOKING AT MODEL SOUNDINGS...DONT EXPECT IFR CIGS TO IMPACT THE CHICAGO AREA TERMINALS. RFD MY FLIRT WITH IFR THROUGH THE MORNING HOURS AND HAVE COVERED THIS WITH A TEMPO GROUP. SHOULD SEE AN IMPROVING TREND THROUGH THE AFTERNOON. THE BACK EDGE OF THE STRATUS OVER THE DAKOTAS...NEB...INTO NW MO IS PUSHING EAST ON SATELLITE IMAGERY. THERE IS A POSSIBILITY OF STRATUS SCATTERING OUT OVER NORTHERN IL TOWARDS EVENING OR OVERNIGHT...BUT CONFIDENCE IN THAT HAPPENING IS LOW AND WILL HANG ON TO MVFR CIGS THROUGH THE NIGHT AT THIS POINT. WINDS WILL GRADUALLY VEER NORTH NORTHEAST LATE TONIGHT INTO MONDAY MORNING. AS COLDER AIR MOVES DOWN THE LAKE...SOME LAKE EFFECT CLOUDS AND LIGHT SNOW SHOWERS ARE POSSIBLE MONDAY BUT AT THIS TIME IT APPEARS THE CLOUD DEPTH WILL BE TOO SHALLOW TO SUPPORT ANY SIGNIFICANT LAKE EFFECT FOR MONDAY. ALLSOPP //ORD AND MDW CONFIDENCE...UPDATED 12Z... * HIGH CONFIDENCE IN WIND FORECAST. * MEDIUM CONFIDENCE ON CIGS REMAINING 1000-1500 THROUGH THE MORNING...THEN LIFTING IN THE AFTERNOON. THERE IS A SLIGHT CHANCE OF IFR CIGS THIS MORNING BUT CONFIDENCE IN THAT HAPPENING AT ORD/MDW IS LOW. * MEDIUM CONFIDENCE IN MVFR CIGS HANGING IN THROUGH THE NIGHT. * HIGH CONFIDENCE IN LIGHT SHOWERS ENDING WITH COLD FRONT PASSAGE AROUND MID THIS MORNING. ALLSOPP //OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z... MONDAY NIGHT...MVFR CIG. CHANCE LIGHT LAKE EFFECT SNOW SHOWERS. TUESDAY...VFR. WEDNESDAY...VFR. THURSDAY...VFR. FRIDAY...VFR. SATURDAY...VFR. ALLSOPP && .MARINE... 133 AM CST A POWERFUL STORM WAS MOVING THROUGH THE GREAT LAKES THIS MORNING. LOW PRESSURE WILL MOVE QUICKLY FROM WISCONSIN TO NORTHERN LAKE MICHIGAN THIS MORNING...THEN ON TO QUEBEC BY EVENING. EAST OF THE TRACK OF THE LOW A VERY STRONG SOUTHERLY LOW LEVEL JET WAS OCCURRING...WITH 50 KT WINDS JUST 1 TO 2 THOUSAND FEET OFF THE SURFACE. A STRONG INVERSION WAS LIMITING MIXING BUT GALE FORCE WINDS WERE WORKING DOWN TO THE LAKE SURFACE OVER THE SOUTH HALF WITH SOME GALE FORCE GUSTS ON THE EAST SIDE OF THE NORTH HALF OF THE LAKE. WINDS SHOULD DROP OFF PRETTY QUICKLY AS THE LOW MOVES RAPIDLY NORTHEAST TODAY AND GALES SHOULD END BY ABOUT NOON. PRESENTLY GALE WARNING GOES THROUGH MID AFTERNOON BUT IT MAY BE CANCELED EARLY. WINDS WILL VEER FROM SOUTH TO NORTHWEST THROUGH THE COURSE OF THE DAY. TONIGHT THROUGH MONDAY ANOTHER LOW WILL MOVE FROM THE TEXAS COAST UP THROUGH THE OHIO VALLEY WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. THIS WILL PRODUCE A PERIOD OF NORTHERLY WINDS ON LAKE MICHIGAN. THE REST OF THE WEEK HIGH PRESSURE WILL DOMINATE THE CENTRAL U.S. WHILE LOW PRESSURE BECOMES ANCHORED OVER NORTHEAST CANADA. THIS WILL PRODUCE A PROLONGED PERIOD OF WESTERLY WINDS OVER LAKE MICHIGAN FROM MID WEEK INTO THE WEEKEND. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 PM SUNDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
539 AM CST SUN DEC 4 2011 .UPDATE... RADAR AND RUC TRENDS INDICATE THE DEFORMATION ZONE PRECIPITATION HAS FALLEN APART AND MOST SFC OBS INDICATE NO PRECIPITATION IS OCCURRING. ISOLATED FLURRIES OR VERY LOCALIZED FZDZ MAY BE OCCURRING IN THE NORTHWEST PART OF THE CWFA BUT MUCH OF THE AREA NOW LOOKS TO REMAIN DRY. THE COLD FRONT IS NOW IN THE EASTERN PART OF THE CWFA AND WILL CLEAR IT BY 14Z AND TAKE WHAT LINGERING RA/SHRA WITH IT. THUS THE CURRENT TREND OF ENDING ALL PRECIP IN THE EASTERN CWFA BY 15Z LOOKS ON TARGET. AS FOR THE CLOUDS...NOT ONE MODEL HAS A HANDLE ON WHAT IS CURRENTLY GOING ON. THE OPENING IN WESTERN IOWA APPEARS TO BE SLOWLY SHRINKING BASED ON RECENT SATELLITE TRENDS. THE CAA POURING INTO THE AREA IS NOT STEEPENING LOW LEVEL LAPSE RATES ALL THAT MUCH BASED ON RECENT RUC TRENDS. EXTRAPOLATION OF THE POCKET OF CLEAR SKIES IN WESTERN IOWA SUGGESTS THAT IT WOULD REMAIN WEST OF THE CWFA DURING THE DAY. TEMPERATURE WISE...HIGH TEMPERATURES IN THE FAR EASTERN CWFA WILL OCCUR OVER THE NEXT 1-2 HRS AND THEN SLOWLY FALL THE REMAINDER OF THE DAY. LOW TEMPERATURES THIS MORNING WILL BE RIGHT AROUND THE 14-15Z TIME FRAME. AN UPDATE TO THE OVERALL FCST FOR TODAY WILL BE AVAILABLE SHORTLY. ..08.. && .AVIATION... NOT ONE MODEL IS CURRENTLY HANDLING THE CLOUD COVER ACROSS THE MIDWEST. CIGS BLO 1KFT AGL WILL SLOWLY RISE AND ACHIEVE 1KFT CIGS 15Z-18Z. THE HOLE OF VFR TO UNLIMITED CIGS IN WESTERN IOWA PER SATELLITE IS A CONCERN BUT RECENT TRENDS SUGGEST THIS HOLE IS FILLING. AFT 18Z CIGS WILL CONTINUE TO SLOWLY RISE BUT SHOULD REMAIN IN THE 1-2KFT AGL RANGE. AFT 02Z/05 CIGS AT ALL TAF SITES SHOULD CLIMB TO 2-3KFT AGL. VSBYS SHOULD REMAIN VFR THROUGH 12Z/05. ..08.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
736 AM EST SUN DEC 4 2011 .SYNOPSIS... RAIN CHANCES WILL BE ON THE INCREASE FOR THE UPPER OHIO VALLEY REGION AS A COLD FRONT MOVES TOWARD...AND THEN ACROSS THE AREA EARLY THIS WEEK. COLDER WEATHER WILL RETURN BY MID WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MADE MINIMAL ALTERATIONS TO TEMPERATURE, CLOUDS, AND WIND BASED ON RECENT SURFACE DATA AND HRRR MODEL OUTPUT. CONTINUE TO EXPECT SOME INCREASE IN CLOUDS WEST TO EAST TOWARD AFTERNOON, AS HIGH PRESSURE EXITS TO THE COAST. LOW PRESSURE CROSSING THE GREAT LAKES WILL DRAG A COLD FRONT TOWARD THE PBZ AREA BY TONIGHT...AND RAIN CHANCES WILL DEVELOP FOR THE WESTERN TIER OF COUNTIES AS THE AFTERNOON PROGRESSES. WITH WARM ADVECTION UNDER SOUTHERLY FLOW...TODAYS HIGHS ARE FORECAST APPROXIMATELY 10 DEGREES ABOVE NORMAL USING GFS MOS GUIDANCE. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... MODELS IN GENERAL AGREEMENT IN SLOWING EASTWARD PROGRESS OF THE FRONT...WITH ONLY LOW...OR NO CHANCE OF RAIN FOR WV/MD/ AND MUCH OF PA WELL INTO MONDAY. CROSSING SHORTWAVE SHOULD DRAG THE FRONT ACROSS MOST OF THE AREA ON TUESDAY...AND POPS WERE INCREASED TO CATEGORICAL NUMBERS FOR THE FINAL ADVANCE AND PASSAGE OF THE BOUNDARY. PROGGED PRECIP AMOUNTS HAVE FALLEN AND DO NOT EXPECT THOSE TOTALS TO EXCEED THE INCH TO INCH AND A HALF RANGE. TEMPERATURES THROUGH TUESDAY WERE FORECAST ABOVE THE NORMALS USING A BLEND OF PERSISTENCE AND GFS MOS. PRECIP CHANCES WERE MAINTAINED THROUGH WEDNESDAY AS UPPER TROUGH IS FORECAST TO DEVELOP ACROSS THE GREAT LAKES...WITH SNOW SHOWERS INCLUDED IN THE COOLER AIR UNDER THAT FEATURE. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... NOT MUCH RUN-TO-RUN CONSISTENCY WITH MODELS IN THE LAST DAY. 00Z GFS PUSHED FRONT OUT TO SEA BY THURSDAY MORNING...THEN THE 12Z GFS BRINGS A HUGE LOW UP THE EAST COAST. 00Z ECMWF HANGS THE FRONT UP ALONG THE COASTLINE...WITH THE 12Z ECMWF SLIGHTLY FARTHER OFFSHORE. 00Z CANADIAN/UKMET SUPPORT THE IDEA OF A BIG LOW DEVELOPING ALONG THE FRONT...BUT HAVE 24-HOUR DIFFERENCES IN THE TIMING. WITH VARYING SOLUTIONS...WILL STICK CLOSE TO HPC SOLUTION...WHICH BLENDS GFS/ECMWF ENSEMBLES...WHICH QUICKLY MOVES THE FRONT OFFSHORE. NEXT FRONT WILL CROSS THE GREAT LAKES FRIDAY INTO SATURDAY...AGAIN WITH VARYING SOLUTIONS AS TO THE INTENSITY. WILL GO WITH CHANCE POPS DURING THIS TIME PERIOD. TEMPS WILL BE ABOUT 5 DEGREES BELOW NORMAL THROUGHOUT THE EXTENDED FORECAST. && .AVIATION /13Z SUNDAY THROUGH THURSDAY/... VFR TO CONTINUE INTO TONIGHT, ALTHOUGH RAIN SHOWERS MAY AFFECT KZZV LATE TONIGHT. EXPECT SOUTHERLY WINDS TO INCREASE LATE THIS MORNING WITH GUSTS TO 20 KTS THIS AFTERNOON. OUTLOOK...MONDAY THROUGH THURSDAY... FRONT WILL STALL OUT ALONG WESTERN BORDER OF THE FORECAST AREA INTO MONDAY. THIS MAY LIMIT RESTRICTIONS IN SHOWERS DURING THIS TIME PERIOD TO KFKL AND KZZV. THE FRONT WILL AFFECT ALL TERMINALS BY MONDAY NIGHT, BRINGING RESTRICTIONS IN SHOWERS. THE FRONT WILL REMAIN ACROSS THE AREA UNTIL AT LEAST TUESDAY NIGHT. MODELS THEN DIVERGE...WITH LITTLE CONFIDENCE IN WHETHER THE FRONT WILL REMAIN OVER THE AREA OR PUSH OFF TO THE EAST. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
515 AM CST SUN DEC 4 2011 .DISCUSSION.../ISSUED AT 311 AM CST/ LIGHT SNOW WHICH AFFECTED PORTIONS OF OUR AREA ON SATURDAY HAS PUSHED INTO CENTRAL MINNESOTA AND CENTRAL IOWA VERY EARLY THIS MORNING. BEHIND THE EXITING SYSTEM...A BROAD AREA OF STRATUS HAS DEVELOPED ACROSS THE EASTERN DAKOTAS INTO EASTERN NEBRASKA...THOUGH MODELS NOT PICKING UP ON THIS AT ALL. 06Z RUC 925 MB RH TIME SECTION HINTING AT IT...AND HAS IT PULLING EASTWARD THROUGH THE MORNING...EXITING OVER OUR FAR EAST BY 18Z. OTHERWISE...A RELATIVELY QUIET DAY IN STORE...WITH CLOUDS INCREASING IN OUR WEST IN THE AFTERNOON AS A WEAK SHORTWAVE DROPS SOUTHWARD ON A NORTHWESTERLY UPPER LEVEL FLOW. NOT MUCH IN THE WAY OF DYNAMICS WITH THIS FEATURE...BUT COULD SPIT OUT SOME VERY LIGHT SNOW IN OUR WEST BY LATE THIS AFTERNOON INTO TONIGHT. TEMPERATURES A BIT TRICKY TODAY IN BETWEEN CLOUD COVER...THOUGH WHAT IS MORE CERTAIN IS THAT READINGS WILL NOT WARM A WHOLE LOT OVER SNOW COVERED AREAS...WITH HIGHS GENERALLY IN THE MID 20S THROUGH NORTHWESTERN IOWA AND PORTIONS OF SOUTHWESTERN MINNESOTA. TO THE WEST...WITH MORE SUN AND BETTER MIXING IN A TRANSITIONING SOUTHWESTERLY LOW LEVEL FLOW...HIGHS WILL REACH THE MID 30S ACROSS THE MUCH OF THE JAMES RIVER VALLEY INTO SOUTH CENTRAL SOUTH DAKOTA. WINDS WILL BECOME NORTHWESTERLY AND PICK UP FROM WEST TO EAST TONIGHT IN A TIGHTENING GRADIENT AND COLD AIR ADVECTION BEHIND THE EXITING SHORTWAVE AND SURFACE LOW/ASSOCIATED FRONTAL BOUNDARY. THE WINDS AND CLOUD COVER WILL KEEP OVERNIGHT LOWS SOMEWHAT IN CHECK...THOUGH WILL STILL DROP INTO THE TEENS...EXCEPT SINGLE DIGITS OVER SNOW COVER. COLDER AIR WILL CONTINUE TO FILTER INTO THE REGION ON MONDAY WITH A SURFACE HIGH BUILDING INTO THE REGION. TEMPERATURES WILL NOT RISE MUCH FROM EARLY MORNING LOWS...WITH HIGHS ONLY IN THE UPPER TEENS TO LOWER 20S. SOUTHERLY FLOW RETURNS TO THE REGION ON TUESDAY BEHIND THE EXITING HIGH...AND TEMPERATURES TRY TO WARM A BIT IN THE WEST...INTO THE MID AND UPPER 20S...WHILE READINGS OVER SNOW COVERED AREAS MAY ACTUALLY BE A LITTLE COOLER THAN MONDAYS HIGHS WITH LESS MIXING...REMAINING ONLY IN THE UPPER TEENS. EVEN WARMER ON WEDNESDAY AHEAD OF THE NEXT ARCTIC SURGE WHICH WILL DIVE SOUTHWARD ON WEDNESDAY NIGHT AND THURSDAY. COULD GET A LITTLE SNOW ALONG THE LEADING EDGE OF THIS SURGE/FRONTAL GRADIENT DURING THAT TIME FRAME...THOUGH ANY SNOW SHOULD BE LIGHT. HIGHS ON WEDNESDAY WILL BE IN THE UPPER 20S TO MID 30S...THEN DROP BACK TO THE LOWER TO MID 20S ON THURSDAY. FRIDAY LOOKS TO BE THE COLDEST DAY OF THE WEEK...WITH HIGHS MID TEENS TO AROUND 20...FOLLOWED BY SOME WARMING ON SATURDAY. LOOKS TO REMAIN DRY BOTH DAYS. && .AVIATION.../FOR THE 12Z TAF ISSUANCE/ LARGE AREA OF STRATUS FROM THE JAMES RIVER EASTWARD AT SUNRISE WILL CONTINUE MOVING EAST AND DISSIPATING ON THE WEST EDGE THROUGH MID MORNING. CEILINGS ARE MVFR WITH NO VISIBILITY RESTRICTIONS IN THIS AREA...AND CLOUDS CHOULD BECOME SCATTERED AT ALL TAF SITES BY 16Z. LIGHT NORTHWEST SURFACE WINDS AT 12Z WILL BECOME SOUTHERLY AT 5 TO 10 KTS THIS AFTERNOON BEFORE SWITCHING BACK TO THE NORTH OR NORTHWEST AT 5 TO 10 KTS THIS EVENING BEHIND A LOW PRESSURE SYSTEM THAT WILL BE MOVING THROUGH THE WESTERN AND CENTRAL DAKOTAS. THERE WILL BE A CHANCE OF LIGHT SNOW MAKING IT AS FAR EAST AS KHON OVERNIGHT BEHIND THE LOW. /MG && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. && $$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
603 AM CST SUN DEC 4 2011 UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE .UPDATED...CONCERNING HEADLINES. AVAILABLE REPORTS IN THE ADVISORY AREA SO FAR THIS EVENING RANGE UP TO 2 INCHES. IR LOOP SHOWS BEST ENHANCEMENT HAS QUICKLY SHIFTED NORTHEASTWARD INTO UPPER MICHIGAN. RADAR AND OBS ACROSS THE REGION INDICATE THE RAIN SNOW LINE EXTENDS FROM NORTHWEST IOWA TO RST TO STE TO JUST SOUTH OF IMT. A SURFACE LOW WAS OVER SOUTHERN IOWA EARLY THIS EVENING AND WILL BE ENTERING SOUTHWEST WISCONSIN LATE THIS EVENING AND NEARLY TRACKING ALONG THE RAIN SNOW LINE OVERNIGHT. A LARGE AREA OF RAIN WAS IN THE WARM SECTOR OF THE LOW OVER IOWA AND SOUTHERN WISCONSIN MOVING TOWARD EASTERN WISCONSIN. PARTS OF EASTERN WISCONSIN MAY SEE UP TO AN ADDITIONAL INCH OF RAIN OVERNIGHT. BUT BACK TO THE ADVISORY...BEST SNOW GROWTH REGION WAS OVER NORTHWEST WISCONSIN AND MAY INCLUDE WESTERN PORTIONS OF ONEIDA AND VILAS COUNTIES. THIS SNOW GROWTH REGION IS PROGGED TO SAG INTO NORTH CENTRAL WISCONSIN OVERNIGHT AS THE H8 LOW AND SURFACE LOW TRACKS OVER. NOT OUT OF THE QUESTION A WARNING MAY BE NEEDED AS THESE MORE FAVORABLE DYNAMICS PLAY A ROLE...BUT FOR NOW WILL CONTINUE THE HIGH END ADVISORY. TDH && .PREV DISCUSSION...ISSUED AT 505 PM CST SAT DEC 3 2011... SHORT TERM...TONIGHT AND SUNDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A DEVELOPING LOW PRESSURE SYSTEM MOVING NORTHEAST OVER SOUTH-CENTRAL KANSAS JUST AHEAD OF A SHORTWAVE TROUGH. ATTACHED TO THE SURFACE LOW TO THE NORTHEAST RUNS A COLD FRONT OVER CENTRAL IOWA INTO NORTHWEST WISCONSIN. FIRST BATCH OF PRECIP IS RIDING ALONG THE 850MB BAROCLINIC ZONE OVER THE SOUTHEASTERN HALF OF WISCONSIN THOUGH SOME BREAKS ARE SPREADING OVER EASTERN IOWA AND NORTHERN ILLINOIS...THAT MAY SPELL A BREAK IN THE PRECIP FOR A BRIEF PERIOD LATE THIS AFTERNOON OVER E-C WISCONSIN. THE MAIN AXIS OF PRECIP...HOWEVER... EXISTS JUST TO THE EAST OF THE SURFACE LOW ON THE NOSE OF A 60 KT LLJ AND UPPER DIVERGENT AREA WITHIN THE COUPLED JET. SOME HIGHER REFLECTIVITIES ARE ALSO DEVELOPING OVER WESTERN WISCONSIN WITHIN A STRENGTHENING FGEN ZONE...SO WILL JUST START THE WINTER HEADLINES WITH THE AFTERNOON PACKAGE. AS THE LOW TRACKS NORTHEAST OVER THE NEXT 24 HOURS...THE OBVIOUS CONCERNS ARE SNOW AMOUNTS AND HEADLINES. TONIGHT...FOLLOWED A SREF/GFS BLEND TONIGHT...WHICH SPLITS THE DIFFERENCE BETWEEN THE STRONGER NAM AND WEAKER ECMWF WHILE KEEPING THE CONSENSUS TRACK. LOW PRESSURE OVER THE CENTRAL PLAINS WILL RAPIDLY MOVE NE TOWARDS THE MID-MISSISSIPPI VALLEY THIS EVENING...AND NORTHERN LAKE MICHIGAN BY 12Z SUNDAY. AHEAD OF THE LOW...A BEEFY LLJ WILL SHIFT INTO SOUTHERN WISCONSIN THIS EVENING...THEREBY INCREASING CONVERGENCE ALONG THE STALLED BAROCLINIC ZONE STRETCHING ACROSS THE STATE...AND 850-700MB FGEN IN THE PROCESS. COMBINED WITH STRONG QG FORCING FROM SHORTWAVE ENERGY AND A WIDE OPEN GULF (PWATS 150-200 PCT OF NORMAL)...THE BEEFY SLUG OF PRECIP OVER THE PLAINS WILL HAVE NO TROUBLE SPREADING ACROSS THE STATE THIS EVENING. PTYPE REMAINS PROBLEMATIC AS THE 12Z MODEL RUNS HAVE TRENDED SLIGHTLY WARMER WITH THE THERMAL PROFILE AS THE LOW PUSHES WARMER AIR ALOFT SLIGHTLY FARTHER NORTH THAN PREVIOUS RUNS. THIS WILL PLACE THE RAIN-SNOW MIX AREA FROM WOOD COUNTY TO NORTHERN OCONTO AND MARINETTE. NORTH OF THE RAIN-SNOW LINE SHOULD RESIDE THE AXIS OF HEAVIEST SNOWFALL...WHICH LINES UP WITH THE EXTRAPOLATED SOUTHERN EDGE OF THE COMMA HEAD FROM APPROX MERRILL TO CRANDON. WITH SLIGHTLY COLDER AIR IN PLACE COMPARED TO THE FIRST SNOW STORM IN NOVEMBER...SNOW RATIOS WILL RUN BETWEEN 10-14:1 OVER THIS AREA ACCORDING TO THE COBB SNOWFALL ALGORITHM. WITH QPFS AROUND 0.4 TO 0.5 INCHES...THIS AMOUNTS TO A GOOD 4-6 INCH SWATH OF SNOW TONIGHT (5 TO 7 INCHES OVERALL)...THOUGH THE BULK OF THE PRECIP WILL LIKELY FALL THIS EVENING. THE FOX VALLEY AND LAKESHORE WILL RESIDE WITHIN THE WARM SECTOR OF THE STORM...WHICH MEANS MOSTLY RAIN TONIGHT...THOUGH SOME SNOW MAY MIX IN LATE. ENTERTAINED SOME THOUGHTS OF UPGRADING TO A WARNING GIVEN THE HEAVY SNOW OBS UPSTREAM...BUT GIVEN THE RELATIVELY LOW IMPACT OF THE SNOW (DURING THE NIGHT ON A WEEKEND)...WILL STICK WITH ADVISORY HEADLINES. ALSO THOUGHT ABOUT TRIMMING THE ADVISORY TO THE NW BY A ROW OF COUNTIES...BUT COORDINATION WITH SURROUNDING OFFICES YIELDED A RELUCTANCE...DUE TO THE SLOPPINESS OF THE MIX AND POTENTIAL FOR FREEZING DRIZZLE. AS A RESULT...WILL KEEP CURRENT HEADLINES AS THEY CURRENTLY STAND BUT STRESS THE HEAVY SNOWFALL RATES ARRIVING THIS EVENING. SUNDAY...THE LOW PRESSURE WILL QUICKLY EXIT TO SOUTHEAST ONTARIO BY 18Z SUNDAY BUT WILL HAVE THE BACK EDGE OF THE COMMA HEAD SHIFTING NE OVER N-C AND FAR NORTHEAST WISCONSIN. SOME MID-LEVEL FGEN WILL LINGER WHICH WILL RESULT IN ANOTHER HALF INCH TO AN INCH OVER N-C WISCONSIN EARLY IN THE MORNING. BUT OTHERWISE...SNOW WILL BE TAPERING DOWN TO JUST FLURRIES IN THE MORNING...WHILE COLDER AIR FILTERS ACROSS THE REGION. LOW LEVEL TROUGHINESS AND CYCLONIC FLOW WILL HANG AROUND FOR MUCH OF THE DAY...SO NOT ANTICIPATING MUCH CLEARING TOMORROW. HIGHS MAINLY IN THE LOW TO MIDDLE 30S. LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY...THE MAIN FCST CONCERNS WILL BE MINOR LAKE EFFECT SNOW POTENTIAL OVER NORTHERN WI EARLY IN THE PERIOD...THEN THE POTENTIAL FOR SNOW AND MUCH COLDER TEMPERATURES WITH AN ARCTIC FRONTAL PASSAGE LATE NEXT WEEK. A STRONG...HIGH AMPLITUDE RIDGE WILL COVER THE EASTERN PACIFIC... WESTERN CANADA AND THE WEST COAST OF THE U.S. EARLY IN THE PERIOD... WITH A POSITIVELY-TILTED UPPER TROF EXTENDING FROM CENTRAL CANADA INTO THE SOUTHWEST UNITED STATES. THIS UPPER TROF WILL MOVE THROUGH WISCONSIN ON TUESDAY...WITH LITTLE IMPACT ON OUR WEATHER. SHORT-WAVE ENERGY WILL TOP THE WESTERN RIDGE EARLY NEXT WEEK...THEN EVENTUALLY HELP TO CARVE A BROAD TROF OVER THE CENTRAL U.S. BY THU/FRI. A SURGE OF ARCTIC AIR IS EXPECTED TO ARRIVE IN WI LATE IN THE WEEK... WITH H8 TEMPS PLUMMETING TO AROUND -20 C. THIS WILL LEAD TO OUR COLDEST TEMPERATURES SO FAR THIS SEASON. A LARGE RIDGE OF HIGH PRESSURE WILL BE CENTERED OVER THE NORTHERN ROCKIES AND NORTHERN PLAINS SUN NGT INTO MON...WITH COLD NORTH FLOW RESULTING IN SCT LAKE-EFFECT SNOW SHOWERS OVER MAINLY NC WI. THE SNOW SHOWERS MAY LINGER INTO MONDAY NIGHT...BUT SHOULD COME TO AN END ON TUESDAY AS THE RIDGE AXIS PUSHES ACROSS WI. A WEAK COLD FRONT IS EXPECTED TO MOVE THROUGH THE REGION ON WEDNESDAY...WITH A STRONGER ARCTIC FRONT ARRIVING SOMETIME DURING THE THU/FRI TIME FRAME. DURING THIS PERIOD...LLVL FLOW IS EXPECTED TO BE TOO WESTERLY FOR LK-EFFECT. THE ECMWF AND A FEW OF THE GFS ENSEMBLE MEMBERS SUGGEST THAT A SFC WAVE WILL DEVELOP ALONG THE ARCTIC BOUNDARY LATE IN THE WEEK...AS THE RRQ OF A STRONG UPPER LEVEL JET PULLS THROUGH THE REGION. IF THIS PLAYS OUT...WE COULD BRING SEE SEVERAL INCHES OF POWDERY SNOW SOMETIME DURING THE THURSDAY NIGHT TO SATURDAY PERIOD. FOR NOW...WILL FOLLOW THE CONCENSUS OF AREA OFFICES...AND JUST MENTION SMALL POPS ACROSS OUR SOUTHERN AND EASTERN COUNTIES ON THU NGT/FRI. THERE IS A HIGHER DEGREE OF CONFIDENCE IN A TREND TOWARD MUCH COLDER TEMPERATURES LATE IN THE WEEK...ALTHOUGH THE NEW ECMWF IS SLOWER WITH THE TIMING OF THE ARCTIC BOUNDARY. SUBSEQUENT FCSTS SHOULD BE BETTER ABLE TO PINPOINT THE FRONTAL TIMING AND SNOWFALL POTENTIAL LATE NEXT WEEK. && .AVIATION...SNOW IS ENDING BUT IFR CIGS WILL LIKELY REMAIN OVER MOST OF THE REGION THROUGH EARLY AFTERNOON AND THEN MVFR IN MOST PLACES. RDM && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
548 AM CST SUN DEC 4 2011 .SHORT TERM...TODAY THROUGH TUESDAY NIGHT 324 AM CST SUN DEC 4 2011 MAIN FORECAST CONCERN NOW THAT THE PRECIPITATION IS EXITING/DIMINISHING IS WHEN CLOUDS WILL CLEAR. CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING STILL OVER THE EAST PACIFIC AND ALONG THE EAST COAST OF THE U.S....AND TROUGHING IN-BETWEEN FROM HUDSON BAY SOUTHWEST INTO ARIZONA. IMPORTANT FEATURES TO NOTE INCLUDE A SHORTWAVE NEAR EAU CLAIRE WI ON THE EAST SIDE OF THE UPPER TROUGH...AND TWO SHORTWAVES OVER MONTANA ON THE BACK SIDE OF THE UPPER TROUGH. THE FORMER SHORTWAVE IN CONJUNCTION WITH PLENTIFUL MOISTURE AND LOW TO MID-LEVEL FRONTOGENESIS BROUGHT THE WIDESPREAD PRECIPITATION TO THE AREA LAST NIGHT. DRY SLOT NOTED IN WATER VAPOR COMBINED NOW WITH THE SHORTWAVE MOVED THROUGH...RESULTING IN SOME SUBSIDENCE...HAS ALLOWED PRECIPITATION TO REALLY DIMINISH DURING THE PAST 4-6 HOURS. IT APPEARS MODELS YESTERDAY MAY HAVE OVERDONE THE LOW LEVEL ISENTROPIC LIFT FOR THE CURRENT EARLY MORNING HOURS... GIVEN THAT THEY NOW SHOW NO ISENTROPIC LIFT AND SEEING THE PRECIPITATION DIMINISH ON RADAR. THEREFORE...THE CONCERN ABOUT THE DRY SLOT CLEARING OUT ICE AND RESULTING IN FREEZING PRECIPITATION IS NOT AS GREAT. IN ADDITION... SURFACE TEMPERATURES HAVE STRUGGLED TO FALL BELOW FREEZING WHERE IR CLOUD TOP TEMPERATURES INDICATE ICE HAS BEEN LOST. REGARDING THE SURFACE...SEA LEVEL PRESSURE ANALYSIS SHOWS A 1008MB LOW NEAR MANITOWOC WI. PLENTY OF CLOUDS EXTEND WEST FROM THE LOW...BACK INTO THE EASTERN DAKOTAS. UPSTREAM...ANOTHER BUT MUCH WEAKER SURFACE LOW IS NOTED NEAR WILLISTON ASSOCIATED WITH ONE OF THE MONTANA SHORTWAVES. TODAY AND TONIGHT...A SHORTWAVE IN EASTERN MONTANA IS PROGGED TO MOVE INTO SOUTH DAKOTA TODAY AND INTO NORTHWEST WISCONSIN TONIGHT. THE TRACK OF THE SHORTWAVE SUGGESTS ALL OF THE FORCING WILL STAY NORTH AND WEST OF THE AREA. THIS IS CONFIRMED TOO BY QG PLOTS. IN ADDITION...IT APPEARS MUCH OF THE CLOUD COVER ASSOCIATED WITH THE SHORTWAVE WILL STAY TO THE NORTHWEST. SO THIS LEAVES THE CURRENT CLOUD COVER AND SYSTEM GOING THROUGH THE MAIN CONCERN. WITH STRATUS EXTENDING SO FAR WEST...GRADUAL SUBSIDENCE OCCURRING TODAY IN THE WAKE OF THE SYSTEM AND THE LOW SUN ANGLE...THINKING A VERY PESSIMISTIC TREND MIGHT BE THE WAY TO GO. LIKE THE 04.00Z NAM INDICATING THE STRATUS STAYS IN PUT ACROSS THE AREA TODAY WITH ONLY SLOW CLEARING TONIGHT FOR WESTERN AREAS. CONCERNED THAT EVEN THE NAM MIGHT BE TOO FAST TONIGHT AS THE 900-950MB WINDS TURN FROM THE NORTHWEST TO NORTH. COMBINED WITH THE RECENT MOISTURE...CLOUDS MAY ACTUALLY LOWER IN CEILING HEIGHT VERSUS CLEARING. LAST CONCERN IS PRECIPITATION...BOTH THIS MORNING AND POSSIBLY OUT OF THE STRATUS DECK TONIGHT. GIVEN DIMINISHING RADAR RETURNS AND DRY FORECASTS INDICATED BY THE 04.00Z NAM/GFS/ECMWF FOR 12-18Z TODAY...HAVE REALLY DRIED OUT THIS MORNING. IN FACT...THERE MAY NOT BE MUCH GOING ON AFTER 12Z. WITH PRECIPITATION RAPIDLY DIMINISHING...WILL CANCEL THE ADVISORY HERE AT 4 AM. TONIGHT...THE 04.00Z NAM/GFS SHOW SOME LIGHT QPF OVER THE NORTH HALF OF WISCONSIN. APPEARS TO RESULT FROM LOW LEVEL CONVERGENCE...ASSOCIATED WITH SURFACE TROUGHING LINGERING BACK FROM THE CURRENT AREA OF LOW PRESSURE NEAR GRB. HAVE ADDED A 20 PERCENT CHANCE OF SNOW INTO THE FORECAST TO ACCOUNT FOR THIS POSSIBILITY. OTHERWISE...TEMPERATURES LOOK LIKE THEY SHOULD STRUGGLE TO RISE TODAY WITH 850MB TEMPS FALLING TO AT LEAST -6 TO -8C AND CLOUDS STAYING PUT. MAYBE A 1 OR 3 DEGREE F RISE IS POSSIBLE FROM THE 6 AM TEMPERATURE. WITH MORE CLOUDS ANTICIPATED TONIGHT...BROUGHT LOW TEMPERATURES UP A FEW DEGREES...ESPECIALLY ALONG AND EAST OF THE MISSISSIPPI RIVER WHERE CLOUDS ARE MORE CERTAIN. WHERE CLOUDS CLEAR OUT...TEMPERATURES COULD FALL INTO THE UPPER SINGLE DIGITS. MONDAY THROUGH TUESDAY NIGHT...BIG STORY/CONCERN HERE IS FORECASTING WHEN THE STRATUS WILL DISSIPATE AND ANY POTENTIAL PRECIPITATION OUT OF IT. UPPER TROUGH SITUATED OVER THE NORTHERN PLAINS IS FORECAST TO MARCH SOUTHEAST DURING THIS PERIOD...IN RESPONSE TO A POWERFUL UPPER TROUGH DIGGING FORMING OVER CENTRAL CANADA. NORTH TO NORTHEAST LOW LEVEL FLOW IS LIKELY MONDAY INTO MONDAY NIGHT WITH HIGH PRESSURE BUILDING INTO THE NORTHERN PLAINS. THIS FLOW SHOULD DO A DECENT JOB IN HOLDING IN THE STRATUS BELOW THE SUBSIDENCE INVERSION...UNTIL MAYBE LATE MONDAY NIGHT WHEN THERE IS SUGGESTION THE FLOW BACKS NORTHWEST TO BRING IN SOME DRIER LOW LEVEL AIR. IN ADDITION...THAT TROUGH MENTIONED IN THE TONIGHT DISCUSSION IS PROGGED TO DROP SOUTHWEST DUE TO THE LOW LEVEL FLOW. CONVERGENCE ALONG THIS TROUGH COULD RESULT IN SOME FLURRY ACTIVITY AND HAVE ADDED IT TO THE FORECAST. 04.00Z CANADIAN MODEL IS EVEN MORE AGGRESSIVE AND SHOWING A FEW HUNDREDTHS. IF OTHER MODELS...SUCH AS THE NAM/GFS START TO SHOW THIS IN LATER RUNS...MAY NEED TO HAVE SOME HIGHER CHANCES ADDED. BETTER POTENTIAL FOR CLEARING EXISTS TUESDAY AS THE SURFACE RIDGE MOVES IN AT THE SAME TIME WITH DAYTIME HEATING...SO INDICATED CLEARING STARTING HERE. UPPER RIDGING THEN BUILDS OVER THE AREA FOR TUESDAY NIGHT AHEAD OF THE POWERFUL UPPER TROUGH...MAINTAINING DRY CONDITIONS WITH GENERALLY MOSTLY CLEAR SKIES. FOR TEMPERATURES... LOOK FOR A COOLING TREND AS THE UPPER TROUGH MOVES IN. DID RAISE LOW TEMPERATURES UP MONDAY NIGHT IN THE CLOUDY SKY AREA...CLOSER TO THE 2 METER NAM12 GUIDANCE. OTHERWISE...A BLEND OF GUIDANCE SEEMED REASONABLE. .LONG TERM...WEDNESDAY THROUGH SATURDAY NIGHT 324 AM CST SUN DEC 4 2011 AFTER WHAT WAS SOME UNCERTAINTY IN THE LONG TERM FORECAST...CAUSED ESPECIALLY BY THE 03.12Z ECMWF SUGGESTING A POSSIBLE ADVISORY-TYPE SNOW MOVING THROUGH FRIDAY/FRIDAY NIGHT...ALL MODELS HAVE COME BACK INTO GREAT AGREEMENT ON THE UPPER AND SURFACE PATTERNS THROUGHOUT THE LONG TERM. IN FACT...THEY LOOK A LOT LIKE WHAT WAS SHOWN BY THE 03.00Z CYCLE. SO FOR NOW WILL CONSIDER THE 03.12Z ECMWF AN ODD OUTLIER. A WEST-NORTHWEST FLOW UPPER PATTERN BEGINS THE LONG TERM...ON THE SOUTH SIDE OF THE POWERFUL TROUGH DROPPING INTO SOUTHERN CANADA. A COLD FRONT LOOKS TO SLIDE THROUGH THE FORECAST AREA ON WEDNESDAY...ENDING A BRIEF WARM SURGE ALOFT CAUSED BY THE UPPER RIDGE. THEN FOR WEDNESDAY NIGHT AND THURSDAY...A SHORTWAVE TROUGH IS FORECAST TO DIG DOWN THE WEST SIDE OF THE CANADA UPPER TROUGH...CAUSING AN UPPER JET TO STRENGTHEN DOWNSTREAM OVER NORTHERN WISCONSIN. RIGHT ENTRANCE REGION FORCING OF THIS JET SHOULD INDUCE SOME MID-LEVEL FRONTOGENESIS...AND COMBINED WITH A LITTLE MOISTURE MAY PRODUCE A BAND OF LIGHT SNOW OVER FAR SOUTHERN SECTION THURSDAY NIGHT. INCLUDED A 20 PERCENT CHANCE FOR THIS. BIGGER IMPACT IS ON FRIDAY WHEN THE SHORTWAVE TROUGH MOVES ACROSS...CAUSING 850MB TEMPS TO TANK FROM -9 TO -13C ON THURSDAY TO AROUND -20C ON FRIDAY. NEEDLESS TO SAY...BELOW NORMAL TEMPERATURES LIKELY. A DRY AND SLOW WARMING TREND SHOULD THEN ENSUE HEADING INTO THE WEEKEND IN RESPONSE TO THE MODELS FORECASTING THE UPPER FLOW BECOMING MORE ZONAL. IN FACT...THE LATEST 04.00Z ECMWF SUGGESTS HIGHS APPROACHING 40 FOR NEXT SUNDAY AS A SURGE OF DOWNSLOPED WARMED PACIFIC AIR FLOWS INTO THE AREA. && .AVIATION...TODAY INTO MONDAY 548 AM CST SUN DEC 4 2011 LOW PRESSURE THAT BROUGHT SNOW AND MVFR/IFR CIGS/VSBYS TO THE TAF SITE SAT/SAT NIGHT WILL CONTINUE TO MOVE AWAY FROM THE AREA TODAY. VFR VSBYS WILL PREVAIL ACROSS MN/WI TODAY/TONIGHT AS DRYER BOUNDARY LAYER AIR SPREADS ACROSS THE AREA ON NORTHWEST WINDS. SUBSIDENCE BEHIND THE LOW IS ON THE WEAK SIDE AND ANOTHER SHORTWAVE WILL BE DROPPING SOUTH INTO THE UPPER MIDWEST FOR TONIGHT/MONDAY. WITH CONSIDERABLE MOISTURE IN THE 925-850MB LAYER LINGERING OVER MN/IA/WI AND SOME WEAK LIFT FROM THE SHORTWAVE DROPPING INTO THE REGION... MVFR CLOUD DECKS ARE EXPECTED TO REMAIN OVER THE TAF SITES THRU TONIGHT AND MONDAY. THERE MAY BE ENOUGH DEPTH OF MOISTURE/CLOUDS AND WEAK CONVERGENCE/LIFT TO PRODUCE SCT FLURRIES ON MON. THESE NOT EXPECTED TO HAVE AN IMPACT ON VSBYS MON. && .ARX WATCHES/WARNINGS/ADVISORIES... 324 AM CST SUN DEC 4 2011 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM....AJ AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS DENVER CO
250 PM MST SUN DEC 4 2011 .SHORT TERM...BROAD UPPER TROF COVERS MUCH OF THE WESTERN U.S. WHILE WATER VAPOR IMAGERY SHOWING NEXT DISTURBANCE DROPPING SOUTH INTO THE MEAN TROF POSITION OVER UTAH. RUC QG FIELDS SHOWING BEST UPWARD FORCING OVER WESTERN CO AND WESTERN WYOMING. THE ASSOCIATED COLD FRONT IS MOVING SOUTH FROM SOUTHERN WYOMING INTO NORTHERN COLORADO WITH GUSTY NORTHERLY WINDS DEVELOPING BEHIND THE FRONT. CEILINGS ARE BEGINNING TO LOWER OVER THE FRONT RANGE WITH SOME VERY LIGHT ECHOES DEVELOPING OVER THE FOOTHILLS. OVERALL...FORECAST IS STILL ON TRACK WITH MAIN CONCERN SNOW AMOUNTS FOR UPCOMING STORM. SNOW AMOUNTS EXPECTED TO BE A BIT LOWER THAN THE LAST STORM...AS QG VERTICAL VELOCITY FIELDS SHOWING THE BEST FORCING ACROSS WESTERN COLORADO WITH LESSER FORCING OVER NORTHEAST COLORADO AND OVERALL MOISTURE IS A BIT LOWER. HIGHEST SNOW AMOUNTS WILL BE OVER THE EAST SLOPE FRONT RANGE FOOTHILLS WITH LESSER AMOUNTS AS YOU MOVE EAST AWAY FROM THE FOOTHILLS. THERE IS SOME GOOD LOW LEVEL INSTABILITY WITH UPSLOPE UP TO AROUND 600MB. WILL KEEP THE CURRENT 3-6 SNOWFALL RANGE OVER THE URBAN CORRIDOR BUT WOULDN`T BE SURPRISED IF AMOUNTS END UP BEING A BIT LOWER. BIG DROPOFF OF SNOW EAST OF INTERSTATE 25 AND AM CONCERNED THAT THERE WON`T BE MUCH SNOW OVER EASTERN WELD COUNTY AND ZONE 45 AND 46 WITH CURRENT ADVISORIES. WILL LEAVE IN PLACE FOR NOW. FOR THE FOOTHILLS WILL STILL GO WITH 5 TO 10 INCHES. EVEN COLDER TEMPERATURES FOR TONIGHT AND MONDAY WITH READINGS IN THE SINGLE DIGITS AND LOWER TEENS FOR THE NEXT 24 HOURS. .LONG TERM...COULD STILL SEE A FEW FLURRIES OCCURRING SOUTH ON INTERSTATE 70 AS THE STORM CONTINUES TO MOVE SOUTH AND COLD HIGH PRESSURE SETTLES IN. TEMPERATURES WILL CONTINUE TO PLUMMET TO BELOW ZERO ACROSS THE AREA. WILL LIKELY SEE VERY COLD TEMPERATURES IN THE HIGH MOUNTAIN VALLEYS...DROPPING TO AROUND -20 TO -30 BY EARLY TUESDAY MORNING. THE PERSISTENT UPPER TROUGH WILL FINALLY MOVE SOUTHEAST OF THE AREA WITH A SHORT WAVE UPPER RIDGE MOVING OVERHEAD HOWEVER FLOW ALOFT WILL STILL BE NORTHERLY. TEMPERATURES WILL WARM SLIGHTLY...BUT HAVE KEPT TEMPERATURES COOLER THAN GUIDANCE AS THE RECENT COLD AIRMASS WILL BE HARD TO SCOUR OUT AND THE SNOW ON THE GROUND WILL LIKELY HAVE AN AFFECT AS WELL. HAVE KEPT HIGHS IN THE TEENS TO UPPER 20S FOR TUESDAY. ON WEDNESDAY...FLOW ALOFT WILL TURN WESTERLY AS A BROAD UPPER TROUGH OVER CANADA DROPS SOUTH. THE WEST WINDS WILL HELP TEMPERATURES WARM DURING THE DAY...THEN A WEAK COLD FRONT WILL DROP SOUTH DURING THE NIGHT. NO REAL PRECIPITATION EXPECT THAT NIGHT...HOWEVER IT WILL RESULT IN COOLER TEMPERATURES AND A SLIGHT CHANCE OF SNOW THURSDAY AS ANOTHER SHORTWAVE TROUGH ROUNDS THE BOTTOM OF THE LARGER TROUGH. THE LARGE SCALE PATTERN WILL CONTINUE TO TRANSITION EAST FRIDAY TO BRING A STRONGER UPPER RIDGE OVER THE ROCKIES BRINGING DRIER WEATHER AND RELATIVELY WARMER AIR FRIDAY AND SATURDAY. INTRODUCING A SLIGHT CHANCE OF PRECIPITATION FOR SUNDAY AS MODELS DISAGREEING ON WHETHER THERE WILL BE ANOTHER TROUGH OR RIDGE OVER THE AREA. && .AVIATION...CEILINGS BEGINNING TO LOWER NORTH OF THE LOCAL TERMINALS WITH CIGS OF 5000-7000 FEET AGL UPSTREAM OVER FNL AND GXY. THIS WILL RESULT IN ILS APPROACHES AROUND 23Z AT DEN AND BJC. THE LIGHT SNOW NOT FAR BEHIND WITH SNOW NOW AT CYS. MORE WIDESPREAD SNOW AT LOCAL AIRPORTS DEVELOPING BETWEEN 02-3Z AND CONTINUING THROUGH ABOUT 08Z. THIS WILL BE THE WINDOW OF MOST OF THE ACCUMULATION SNOW. MOST OF THE SNOW WILL BECOME VERY LIGHT AND JUST FLURRIES DURING THE DAY ON MONDAY WITH ACCUMULATIONS UNDER AN INCH. STILL TOTAL ACCUMULATIONS OF 3 TO 6 INCHES...WITH 2-3 AT DIA...3-4 AT APA AND 4 TO 6 AT BJC. && .BOU WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM MST MONDAY FOR THE URBAN CORRIDOR...PALMER DIVIDE AND ADJACENT PLAINS...ZONES COZ038>041-043-045-046. WINTER WEATHER ADVISORY UNTIL 11 AM MST MONDAY FOR THE FOOTHILLS AND SOUTH PARK...ZONES COZ035>037. && $$ SHORT TERM...ENTREKIN LONG TERM....KRIEDERMAN AVIATION...ENTREKIN
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
154 PM CST SUN DEC 4 2011 .DISCUSSION... 1125 AM CST FRONTAL BOUNDARY CONTINUES TO STEADILY PUSH EAST ACROSS THE CWFA...EXPECTED BY MIDDAY TO PUSH THROUGH NORTHWEST INDIANA. BEHIND THIS BOUNDARY TEMPERATURES IN MANY LOCATIONS HAVE FALLEN INTO THE UPPER 30S TO LOWER 40S. EXPECT TEMPERATURES TO REMAIN NEARLY STEADY THROUGHOUT THE REMAINDER OF THE DAY...THEN SLOWLY BEGIN TO FALL THIS EVENING. ONE CAVEAT FOR HOW LOW TEMPERATURES MAY FALL TONIGHT WILL BE THE POSSIBILITY OF ABUNDANT CLOUD COVER. CURRENT GUIDANCE CONTINUES TO INDICATE THAT SKIES WILL STEADILY BREAK-UP THIS AFTERNOON AND POSSIBLY TURN SCATTERED TONIGHT. HOWEVER...LOOKING AT THE CURRENT VISIBLE IMAGERY ACROSS THE ENTIRE REGION AND MANY LOCATIONS UPSTREAM THIS SCENARIO OF THINNING SKIES LOOKS TO BE IN JEOPARDY. THUS HAVE CONCERNS ABOUT HOW COLD WE WILL SEE TEMPERATURES FALL TONIGHT. NONETHELESS 850MB THERMAL TROUGH CONTINUES TO PIVOT EAST...AND REMAIN OVERHEAD TONIGHT. AIDING IN TEMPERATURES FALLING INTO THE UPPER 20S TO LOWER 30S TONIGHT WILL BE THE STEADY COLD AIR ADVECTION WITH NORTHERLY WINDS TURNING NORHTEASTERLY. WITH AN INCREASING THERMAL DIFFERENTIAL ACROSS THE RELATIVELY WARMER MARINE ENVIRONMENT...AND MUCH COOLER AIR ALOFT EXPECT A NARROW CHANNEL OF LAKE MOISTURE TO FORM FROM THE NORTH/NORTHEAST WINDS. THIS WILL AID IN THE POSSIBILITY OF LAKE EFFECT FLURRIES/LGT SN. THEN BECOMING MIXED WITH LGT RA AFTER DAYBREAK MON. THROWING A POTENTIAL MONKEY WRENCH IN THIS SCENARIO COULD BE THE DEPTH OF THE FAVORED DENDRITIC GROWTH ZONE AND MOISTURE. VERY MINIMAL VERTICAL ENERGY MAY LIMIT THIS TO POSSIBLY JUST SOME DRIZZLE. THIS WILL BE THE FIRST CHALLENGE OF THE EVENING FORECAST. AS THIS COULD END UP BEING FROZEN DRIZZLE WITH TEMPERATURES POSSIBLY IN THE LOWER 30S. BEACHLER //PREV DISCUSSION... 340 AM CST HIGHLIGHTS THIS WEEK WILL INCLUDE RAIN COMING TO AN END...POSSIBLE SN/RASN/RA ACROSS THE SOUTHEAST MONDAY...LES POTENTIAL FOR LAKE/COOK LATE SUNDAY NIGHT INTO MONDAY...TRANSITIONING SOUTH TO LAKE/PORTER INDIANA BY TUESDAY...A FEW DAYS OF QUIET...FOLLOWED BY A LATE CLIPPER AND SNOW POTENTIAL AND FINALLY A BLAST OF COLD BY NEXT WEEKEND. THE EARLY MORNING SURFACE MAP SHOWED THE SURFACE LOW THAT HAS BEEN BRINGING THE WET AND ACTIVE WEATHER TO THE AREA TODAY...CONTINUING TO LIFTING NORTH THROUGH CENTRAL WISCONSIN. MEANWHILE AN ATTENDANT COLD FRONT LAY ROUGHLY ACROSS THE MISSISSIPPI RIVER...SOUTHWEST NEARLY TO ST LOUIS. THIS FRONT WILL CONTINUE TO SLOWLY SWEEP FROM WEST TO EAST THIS MORNING EVENTUALLY PUSHING ITSELF AND THE PRECIP EAST. THE MOST WIDE SPREAD ECHOES HAVE PUSHED EAST AND ONLY A FEW SCATTERED SHOWERS ARE LOCATED WITH THE ACTUAL FRONT. ACROSS EAST CENTRAL IOWA...TEMPERATURES HAVE DROPPED ENOUGH THAT -SN WAS REPORTED...BUT CLOUD TOPS HAVE WARMED ENOUGH AND ARE WARMER THAN -10C. THIS MEANS THAT THERE IS NO LONGER ICE INTRODUCTION INTO THE SATURATED LAYERS BELOW...AND A FEW LOCATIONS REPORTED U.P. AND OR FZDZ. FOR OUR AREA...AFTER THE FRONT MOVES THROUGH...LOWER LEVEL MOISTURE WILL REMAIN BUT PROFILES ARE STILL INDICATIVE OF LIQUID PRECIP AND SURFACE TEMPS WILL REMAIN ABOVE FREEZING. THE HRRR AND RUC BOTH HAVE A GOOD HANDLE ON THE WESTERN EDGE OF THE PRECIP AND FRONTAL LOCATION...AND MOST OF IT SHOULD CLEAR THE ROCKFORD CORRIDOR NEAR SUNRISE...WITH CHICAGO AND EAST JUST A FEW HOURS BEYOND. WHILE LOWER LEVEL RH WILL REMAIN PREVALENT WITH AND SHORTLY BEYOND FROPA...MOISTURE ABOVE -10C WILL DISAPPEAR AND THERE MAY BE SOME LINGERING DZ INTO THE EARLY MORNING HOURS. THE BIG PUSH OF COLDER AIR ISNT EXPECTED UNTIL LATER THIS EVENING AND TEMPERATURES WILL REMAIN ABOVE FREEZING...SO NO CONCERN OVER ANY OTHER PRECIP TYPES THIS MORNING. HIGH TEMPS WILL GENERALLY BE SEEN EARLY TODAY...AND SLOWLY FALL THROUGH THE DAY. WINDS WILL ABATE AS HIGH PRESSURE AND A PERIOD OF DRY...SLOWLY MOVE IN. THE MAIN UPPER LEVEL TROUGHING THAT STRETCHES FROM ROUGHLY SASKATCHEWAN...SOUTHWEST THROUGH THE FOUR CORNERS REGION WILL NOT HAVE MUCH REASON TO MOVE UNTIL THE START OF THE WORKWEEK. PRESENT SHORTWAVE SEEN ON WATER VAPOR IMAGERY ROUNDING THE BASE OF THE TROUGH...ACROSS SOUTHERN ARIZONA...WILL DAMPEN SOME AS IT GETS EJECTED ON THE EASTERN FLANK TODAY AND TONIGHT. AS IT DOES THIS...IT WILL HELP TO AMPLIFY AN INVERTED TROUGH THAT WILL NOSE ITS WAY TOWARDS THE OHIO VALLEY...EVENTUALLY SPAWNING A WEAK LOW ACROSS THE TENNESSEE VALLEY. GUIDANCE HAS BEEN HEMMING AND HAWING WITH JUST HOW FAR NORTH TO BRING THE PRECIP WITH THIS FEATURE...AND JUST HOW MUCH OF IT WILL REACH INTO THE SOUTHEASTERN CORNER OF THE CWA. THE LATEST FORECAST TRENDS HAVE BACKED OFF FROM PREVIOUS...AND DID SCALE BACK ON POPS AS WELL AS COVERAGE. STILL A LITTLE UNCERTAIN WITH WHERE THE RASN VS STRAIGHT RA LINE WOULD BE AND WILL MAINTAIN A SORT OF MIX. ALSO OF NOTE FOR COASTAL LOCATIONS IN THIS SAME TIME FRAME /AS THE INV TROF-LOW SLIDE EAST/ IS THE CHANCE FOR LES. THERMAL PROFILES ACROSS THE SOUTHERN LAKE WILL BECOME INCREASINGLY UNSTABLE WITH LAKE SURFACE TO H85 DELTA T`S REACHING THE 12-15C RANGE. EXPECT WEAK SHOWERS TO BEGIN TO STRETCH FROM LAKE COUNTY IL...EVENTUALLY SOUTH TO COOK AND GRADUALLY INTO THE MORE TYPICAL LAKE/PORTER IN ORIENTATION. QPF AMOUNTS NOT LOOKING VERY IMPRESSIVE DURING THE SHORT DURATION AND WOULD ONLY EXPECT ANYWHERE FROM A TRACE TO MAYBE A TENTH OR TWO OF ACCUMULATION CLOSE TO THE LAKE TOMORROW AND INTO TOMORROW NIGHT. THIS WILL ALL BE FOLLOWED BY A FEW DAYS OF QUIET AS ANOTHER RIDGE OF HIGH PRESSURE SWINGS IN FROM THE NORTHWEST. A LATE WEEK SYSTEM IS STILL PART OF A LOW CONFIDENCE FORECAST. GFS HAD BEEN ADVERTISING A WEAK CLIPPER DROPPING FROM THE NORTHERN PLAINS... AND PREVIOUS EC SOLNS HAD SIMILAR...BUT THE 12Z FLIPPED AND DEVELOPED A SURFACE LOW THAT LIFTS THROUGH THE MISSISSIPPI VALLEY...INTO NORTHERN INDIANA...NORTHEAST THROUGH EASTERN ONTARIO. CONFIDENCE AT THIS POINT ON THAT EURO SOLN IS LOW AND WILL KEEP THE CHANCE OF SNOW AND NOT BUMP UP (OR DOWN) ANY CATEGORY UNTIL THE PICTURE IS A LITTLE CLEARER. THE 00Z SOLN BEGAN TO COME IN AND WAS BACK TO THE ORIGINAL PICTURE WITH THE CLIPPER RACING THROUGH. DESPITE THE LOWER CONFIDENCE IN THAT FEATURE LATE THIS WEEK...THE ONE PICTURE OF CLARITY WHAT WILL FOLLOW IT. ALL LONG RANGE GUIDANCE IS STILL INDICATING THAT THERE WILL BE A LARGE SURGE OF COLD AIR ENCROACHING AS AN UPPER LEVEL TROUGH SWINGS THROUGH. THERE ARE STILL SOME TIMING DIFFERENCES WITH HOW QUICKLY THE COLD AIR WILL DUMP IN...WHICH IS DUE IN PART TO THE LARGE MODEL DIFFERENCES MENTIONED MOMENTS AGO...BUT THE ONE THING THEY ALL AGREE ON IS HOW COLD THE LOWER LEVELS WILL GET INTO THE WEEKEND. EVEN A WEEK OUT...THE EC/GFS/GEFS/DGEX/GEM(NHEM THROUGH F144) ALL HIGHLIGHT H85 TEMPS PLUMMETING TO -16 TO -18 DEGREES...OR EVEN A FEW DEGREES COLDER. TRANSLATE THAT TO THE SURFACE AND IT WOULD BE POSSIBLE THAT HIGHS WOULD STRUGGLE TO GET OUT OF THE TEENS FOR MANY LOCATIONS AND OVERNIGHT LOWS LEADING INTO THE WEEKEND WOULD DIVE BOMB TO THE SINGLE DIGITS /BUT LIKELY A SMIDGEN WARMER IN THE CHICAGO METRO/. WITH THAT FORECAST STILL BEING OUT 6-7 DAYS...AND A SLEW OF OTHER WEATHER GOING ON THROUGH THE EARLY WEEK... WILL ONLY CONTINUE TO TREND DOWN FROM THE INHERITED LONG RANGE FORECAST. THE BIG SAVING GRACE IS THE LACK OF SOLID SNOW PACK. IF THAT WERE PRESENT...IT WOULD BE MUCH COLDER. SHEA && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * CIG TRENDS THIS AFTERNOON. * POTENTIAL FOR SOME LAKE EFFECT RAIN/SNOW SHOWERS ON MONDAY. KJB //DISCUSSION...UPDATED 18Z... THE MAIN CONCERNS THIS AFTERNOON ARE THE IFR CIGS MOVING ACROSS NORTHEASTERN ILLINOIS. A COLD FRONT IS CURRENTLY MOVING ACROSS NORTHEASTERN ILLINOIS. CIGS ALONG AND BEHIND THIS FRONT HAVE DROPPED INTO THE IFR RANGE. I EXPECT THESE CIGS TO LAST FOR A COUPLE OF HOURS THIS AFTERNOON BEFORE THEY BEGIN TO IMPROVE SOME BY MID TO LATE AFTERNOON. WINDS WILL PRIMARILY BE WESTERLY WITH A FEW GUSTS AROUND 18KT POSSIBLE EARLY THIS AFTERNOON. THE NEXT WEATHER CONCERN WILL BE ON MONDAY AS NORTH TO NORTHEASTERLY FLOW SETS UP AHEAD OF HIGH PRESSURE ACROSS THE PLAINS STATES. THIS FLOW PATTERN...IN COMBINATION WITH THE RELATIVELY COLD TEMPERATURES OVER LAKE MICHIGAN COULD SET THE STAGE FOR SOME LOWER MVFR CIGS AND SOME LAKE EFFECT RAIN AND SNOW SHOWERS BEGINNING EARLY MONDAY MORNING. KJB //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM CONFIDENCE IN CIGS IMPROVING TO LOW END MVFR AROUND 21 UTC. KJB //OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z... MONDAY NIGHT...MVFR CIG. CHANCE LIGHT LAKE EFFECT SNOW SHOWERS. TUESDAY...VFR. WEDNESDAY...VFR. THURSDAY...VFR. FRIDAY...VFR. SATURDAY...VFR. ALLSOPP && .MARINE... 153 PM CST HIGH PRESSURE WILL BUILD ACROSS THE PLAINS STATES ON MONDAY...SETTING UP NORTH TO NORTHEASTERLY FLOW DOWN LAKE MICHIGAN. THE FLOW WILL TURN MORE WESTERLY LATE TUESDAY INTO WEDNESDAY AS A POTENT STORM SYSTEM MOVES EAST ACROSS NORTHERN CANADA. THIS LOW WILL PUSH A COLD FRONT ACROSS LAKE MICHIGAN WEDNESDAY NIGHT. VERY COLD AIR BEHIND THIS FRONT LOOKS TO SET UP AN UNSTABLE ATMOSPHERE ACROSS THE LAKE LATER THIS WEEK. THIS LOOKS TO SET UP CONDITIONS FAVORABLE FOR SOME LAKE EFFECT SNOW SHOWERS. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1149 AM CST SUN DEC 4 2011 .DISCUSSION... 1125 AM CST FRONTAL BOUNDARY CONTINUES TO STEADILY PUSH EAST ACROSS THE CWFA...EXPECTED BY MIDDAY TO PUSH THROUGH NORTHWEST INDIANA. BEHIND THIS BOUNDARY TEMPERATURES IN MANY LOCATIONS HAVE FALLEN INTO THE UPPER 30S TO LOWER 40S. EXPECT TEMPERATURES TO REMAIN NEARLY STEADY THROUGHOUT THE REMAINDER OF THE DAY...THEN SLOWLY BEGIN TO FALL THIS EVENING. ONE CAVEAT FOR HOW LOW TEMPERATURES MAY FALL TONIGHT WILL BE THE POSSIBILITY OF ABUNDANT CLOUD COVER. CURRENT GUIDANCE CONTINUES TO INDICATE THAT SKIES WILL STEADILY BREAK-UP THIS AFTERNOON AND POSSIBLY TURN SCATTERED TONIGHT. HOWEVER...LOOKING AT THE CURRENT VISIBLE IMAGERY ACROSS THE ENTIRE REGION AND MANY LOCATIONS UPSTREAM THIS SCENARIO OF THINNING SKIES LOOKS TO BE IN JEOPARDY. THUS HAVE CONCERNS ABOUT HOW COLD WE WILL SEE TEMPERATURES FALL TONIGHT. NONETHELESS 850MB THERMAL TROUGH CONTINUES TO PIVOT EAST...AND REMAIN OVERHEAD TONIGHT. AIDING IN TEMPERATURES FALLING INTO THE UPPER 20S TO LOWER 30S TONIGHT WILL BE THE STEADY COLD AIR ADVECTION WITH NORTHERLY WINDS TURNING NORHTEASTERLY. WITH AN INCREASING THERMAL DIFFERENTIAL ACROSS THE RELATIVELY WARMER MARINE ENVIRONMENT...AND MUCH COOLER AIR ALOFT EXPECT A NARROW CHANNEL OF LAKE MOISTURE TO FORM FROM THE NORTH/NORTHEAST WINDS. THIS WILL AID IN THE POSSIBILITY OF LAKE EFFECT FLURRIES/LGT SN. THEN BECOMING MIXED WITH LGT RA AFTER DAYBREAK MON. THROWING A POTENTIAL MONKEY WRENCH IN THIS SCENARIO COULD BE THE DEPTH OF THE FAVORED DENDRITIC GROWTH ZONE AND MOISTURE. VERY MINIMAL VERTICAL ENERGY MAY LIMIT THIS TO POSSIBLY JUST SOME DRIZZLE. THIS WILL BE THE FIRST CHALLENGE OF THE EVENING FORECAST. AS THIS COULD END UP BEING FROZEN DRIZZLE WITH TEMPERATURES POSSIBLY IN THE LOWER 30S. BEACHLER //PREV DISCUSSION... 340 AM CST HIGHLIGHTS THIS WEEK WILL INCLUDE RAIN COMING TO AN END...POSSIBLE SN/RASN/RA ACROSS THE SOUTHEAST MONDAY...LES POTENTIAL FOR LAKE/COOK LATE SUNDAY NIGHT INTO MONDAY...TRANSITIONING SOUTH TO LAKE/PORTER INDIANA BY TUESDAY...A FEW DAYS OF QUIET...FOLLOWED BY A LATE CLIPPER AND SNOW POTENTIAL AND FINALLY A BLAST OF COLD BY NEXT WEEKEND. THE EARLY MORNING SURFACE MAP SHOWED THE SURFACE LOW THAT HAS BEEN BRINGING THE WET AND ACTIVE WEATHER TO THE AREA TODAY...CONTINUING TO LIFTING NORTH THROUGH CENTRAL WISCONSIN. MEANWHILE AN ATTENDANT COLD FRONT LAY ROUGHLY ACROSS THE MISSISSIPPI RIVER...SOUTHWEST NEARLY TO ST LOUIS. THIS FRONT WILL CONTINUE TO SLOWLY SWEEP FROM WEST TO EAST THIS MORNING EVENTUALLY PUSHING ITSELF AND THE PRECIP EAST. THE MOST WIDE SPREAD ECHOES HAVE PUSHED EAST AND ONLY A FEW SCATTERED SHOWERS ARE LOCATED WITH THE ACTUAL FRONT. ACROSS EAST CENTRAL IOWA...TEMPERATURES HAVE DROPPED ENOUGH THAT -SN WAS REPORTED...BUT CLOUD TOPS HAVE WARMED ENOUGH AND ARE WARMER THAN -10C. THIS MEANS THAT THERE IS NO LONGER ICE INTRODUCTION INTO THE SATURATED LAYERS BELOW...AND A FEW LOCATIONS REPORTED U.P. AND OR FZDZ. FOR OUR AREA...AFTER THE FRONT MOVES THROUGH...LOWER LEVEL MOISTURE WILL REMAIN BUT PROFILES ARE STILL INDICATIVE OF LIQUID PRECIP AND SURFACE TEMPS WILL REMAIN ABOVE FREEZING. THE HRRR AND RUC BOTH HAVE A GOOD HANDLE ON THE WESTERN EDGE OF THE PRECIP AND FRONTAL LOCATION...AND MOST OF IT SHOULD CLEAR THE ROCKFORD CORRIDOR NEAR SUNRISE...WITH CHICAGO AND EAST JUST A FEW HOURS BEYOND. WHILE LOWER LEVEL RH WILL REMAIN PREVALENT WITH AND SHORTLY BEYOND FROPA...MOISTURE ABOVE -10C WILL DISAPPEAR AND THERE MAY BE SOME LINGERING DZ INTO THE EARLY MORNING HOURS. THE BIG PUSH OF COLDER AIR ISNT EXPECTED UNTIL LATER THIS EVENING AND TEMPERATURES WILL REMAIN ABOVE FREEZING...SO NO CONCERN OVER ANY OTHER PRECIP TYPES THIS MORNING. HIGH TEMPS WILL GENERALLY BE SEEN EARLY TODAY...AND SLOWLY FALL THROUGH THE DAY. WINDS WILL ABATE AS HIGH PRESSURE AND A PERIOD OF DRY...SLOWLY MOVE IN. THE MAIN UPPER LEVEL TROUGHING THAT STRETCHES FROM ROUGHLY SASKATCHEWAN...SOUTHWEST THROUGH THE FOUR CORNERS REGION WILL NOT HAVE MUCH REASON TO MOVE UNTIL THE START OF THE WORKWEEK. PRESENT SHORTWAVE SEEN ON WATER VAPOR IMAGERY ROUNDING THE BASE OF THE TROUGH...ACROSS SOUTHERN ARIZONA...WILL DAMPEN SOME AS IT GETS EJECTED ON THE EASTERN FLANK TODAY AND TONIGHT. AS IT DOES THIS...IT WILL HELP TO AMPLIFY AN INVERTED TROUGH THAT WILL NOSE ITS WAY TOWARDS THE OHIO VALLEY...EVENTUALLY SPAWNING A WEAK LOW ACROSS THE TENNESSEE VALLEY. GUIDANCE HAS BEEN HEMMING AND HAWING WITH JUST HOW FAR NORTH TO BRING THE PRECIP WITH THIS FEATURE...AND JUST HOW MUCH OF IT WILL REACH INTO THE SOUTHEASTERN CORNER OF THE CWA. THE LATEST FORECAST TRENDS HAVE BACKED OFF FROM PREVIOUS...AND DID SCALE BACK ON POPS AS WELL AS COVERAGE. STILL A LITTLE UNCERTAIN WITH WHERE THE RASN VS STRAIGHT RA LINE WOULD BE AND WILL MAINTAIN A SORT OF MIX. ALSO OF NOTE FOR COASTAL LOCATIONS IN THIS SAME TIME FRAME /AS THE INV TROF-LOW SLIDE EAST/ IS THE CHANCE FOR LES. THERMAL PROFILES ACROSS THE SOUTHERN LAKE WILL BECOME INCREASINGLY UNSTABLE WITH LAKE SURFACE TO H85 DELTA T`S REACHING THE 12-15C RANGE. EXPECT WEAK SHOWERS TO BEGIN TO STRETCH FROM LAKE COUNTY IL...EVENTUALLY SOUTH TO COOK AND GRADUALLY INTO THE MORE TYPICAL LAKE/PORTER IN ORIENTATION. QPF AMOUNTS NOT LOOKING VERY IMPRESSIVE DURING THE SHORT DURATION AND WOULD ONLY EXPECT ANYWHERE FROM A TRACE TO MAYBE A TENTH OR TWO OF ACCUMULATION CLOSE TO THE LAKE TOMORROW AND INTO TOMORROW NIGHT. THIS WILL ALL BE FOLLOWED BY A FEW DAYS OF QUIET AS ANOTHER RIDGE OF HIGH PRESSURE SWINGS IN FROM THE NORTHWEST. A LATE WEEK SYSTEM IS STILL PART OF A LOW CONFIDENCE FORECAST. GFS HAD BEEN ADVERTISING A WEAK CLIPPER DROPPING FROM THE NORTHERN PLAINS... AND PREVIOUS EC SOLNS HAD SIMILAR...BUT THE 12Z FLIPPED AND DEVELOPED A SURFACE LOW THAT LIFTS THROUGH THE MISSISSIPPI VALLEY...INTO NORTHERN INDIANA...NORTHEAST THROUGH EASTERN ONTARIO. CONFIDENCE AT THIS POINT ON THAT EURO SOLN IS LOW AND WILL KEEP THE CHANCE OF SNOW AND NOT BUMP UP (OR DOWN) ANY CATEGORY UNTIL THE PICTURE IS A LITTLE CLEARER. THE 00Z SOLN BEGAN TO COME IN AND WAS BACK TO THE ORIGINAL PICTURE WITH THE CLIPPER RACING THROUGH. DESPITE THE LOWER CONFIDENCE IN THAT FEATURE LATE THIS WEEK...THE ONE PICTURE OF CLARITY WHAT WILL FOLLOW IT. ALL LONG RANGE GUIDANCE IS STILL INDICATING THAT THERE WILL BE A LARGE SURGE OF COLD AIR ENCROACHING AS AN UPPER LEVEL TROUGH SWINGS THROUGH. THERE ARE STILL SOME TIMING DIFFERENCES WITH HOW QUICKLY THE COLD AIR WILL DUMP IN...WHICH IS DUE IN PART TO THE LARGE MODEL DIFFERENCES MENTIONED MOMENTS AGO...BUT THE ONE THING THEY ALL AGREE ON IS HOW COLD THE LOWER LEVELS WILL GET INTO THE WEEKEND. EVEN A WEEK OUT...THE EC/GFS/GEFS/DGEX/GEM(NHEM THROUGH F144) ALL HIGHLIGHT H85 TEMPS PLUMMETING TO -16 TO -18 DEGREES...OR EVEN A FEW DEGREES COLDER. TRANSLATE THAT TO THE SURFACE AND IT WOULD BE POSSIBLE THAT HIGHS WOULD STRUGGLE TO GET OUT OF THE TEENS FOR MANY LOCATIONS AND OVERNIGHT LOWS LEADING INTO THE WEEKEND WOULD DIVE BOMB TO THE SINGLE DIGITS /BUT LIKELY A SMIDGEN WARMER IN THE CHICAGO METRO/. WITH THAT FORECAST STILL BEING OUT 6-7 DAYS...AND A SLEW OF OTHER WEATHER GOING ON THROUGH THE EARLY WEEK... WILL ONLY CONTINUE TO TREND DOWN FROM THE INHERITED LONG RANGE FORECAST. THE BIG SAVING GRACE IS THE LACK OF SOLID SNOW PACK. IF THAT WERE PRESENT...IT WOULD BE MUCH COLDER. SHEA && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * CIG TRENDS THIS AFTERNOON. * POTENTIAL FOR SOME LAKE EFFECT RAIN/SNOW SHOWERS ON MONDAY. KJB //DISCUSSION...UPDATED 18Z... THE MAIN CONCERNS THIS AFTERNOON ARE THE IFR CIGS MOVING ACROSS NORTHEASTERN ILLINOIS. A COLD FRONT IS CURRENTLY MOVING ACROSS NORTHEASTERN ILLINOIS. CIGS ALONG AND BEHIND THIS FRONT HAVE DROPPED INTO THE IFR RANGE. I EXPECT THESE CIGS TO LAST FOR A COUPLE OF HOURS THIS AFTERNOON BEFORE THEY BEGIN TO IMPROVE SOME BY MID TO LATE AFTERNOON. WINDS WILL PRIMARILY BE WESTERLY WITH A FEW GUSTS AROUND 18KT POSSIBLE EARLY THIS AFTERNOON. THE NEXT WEATHER CONCERN WILL BE ON MONDAY AS NORTH TO NORTHEASTERLY FLOW SETS UP AHEAD OF HIGH PRESSURE ACROSS THE PLAINS STATES. THIS FLOW PATTERN...IN COMBINATION WITH THE RELATIVELY COLD TEMPERATURES OVER LAKE MICHIGAN COULD SET THE STAGE FOR SOME LOWER MVFR CIGS AND SOME LAKE EFFECT RAIN AND SNOW SHOWERS BEGINNING EARLY MONDAY MORNING. KJB //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM CONFIDENCE IN CIGS IMPROVING TO LOW END MVFR AROUND 21 UTC. KJB //OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z... MONDAY NIGHT...MVFR CIG. CHANCE LIGHT LAKE EFFECT SNOW SHOWERS. TUESDAY...VFR. WEDNESDAY...VFR. THURSDAY...VFR. FRIDAY...VFR. SATURDAY...VFR. ALLSOPP && .MARINE... 133 AM CST A POWERFUL STORM WAS MOVING THROUGH THE GREAT LAKES THIS MORNING. LOW PRESSURE WILL MOVE QUICKLY FROM WISCONSIN TO NORTHERN LAKE MICHIGAN THIS MORNING...THEN ON TO QUEBEC BY EVENING. EAST OF THE TRACK OF THE LOW A VERY STRONG SOUTHERLY LOW LEVEL JET WAS OCCURRING...WITH 50 KT WINDS JUST 1 TO 2 THOUSAND FEET OFF THE SURFACE. A STRONG INVERSION WAS LIMITING MIXING BUT GALE FORCE WINDS WERE WORKING DOWN TO THE LAKE SURFACE OVER THE SOUTH HALF WITH SOME GALE FORCE GUSTS ON THE EAST SIDE OF THE NORTH HALF OF THE LAKE. WINDS SHOULD DROP OFF PRETTY QUICKLY AS THE LOW MOVES RAPIDLY NORTHEAST TODAY AND GALES SHOULD END BY ABOUT NOON. PRESENTLY GALE WARNING GOES THROUGH MID AFTERNOON BUT IT MAY BE CANCELED EARLY. WINDS WILL VEER FROM SOUTH TO NORTHWEST THROUGH THE COURSE OF THE DAY. TONIGHT THROUGH MONDAY ANOTHER LOW WILL MOVE FROM THE TEXAS COAST UP THROUGH THE OHIO VALLEY WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. THIS WILL PRODUCE A PERIOD OF NORTHERLY WINDS ON LAKE MICHIGAN. THE REST OF THE WEEK HIGH PRESSURE WILL DOMINATE THE CENTRAL U.S. WHILE LOW PRESSURE BECOMES ANCHORED OVER NORTHEAST CANADA. THIS WILL PRODUCE A PROLONGED PERIOD OF WESTERLY WINDS OVER LAKE MICHIGAN FROM MID WEEK INTO THE WEEKEND. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 PM SUNDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1135 AM CST SUN DEC 4 2011 .DISCUSSION... 1125 AM CST FRONTAL BOUNDARY CONTINUES TO STEADILY PUSH EAST ACROSS THE CWFA...EXPECTED BY MIDDAY TO PUSH THROUGH NORTHWEST INDIANA. BEHIND THIS BOUNDARY TEMPERATURES IN MANY LOCATIONS HAVE FALLEN INTO THE UPPER 30S TO LOWER 40S. EXPECT TEMPERATURES TO REMAIN NEARLY STEADY THROUGHOUT THE REMAINDER OF THE DAY...THEN SLOWLY BEGIN TO FALL THIS EVENING. ONE CAVEAT FOR HOW LOW TEMPERATURES MAY FALL TONIGHT WILL BE THE POSSIBILITY OF ABUNDANT CLOUD COVER. CURRENT GUIDANCE CONTINUES TO INDICATE THAT SKIES WILL STEADILY BREAK-UP THIS AFTERNOON AND POSSIBLY TURN SCATTERED TONIGHT. HOWEVER...LOOKING AT THE CURRENT VISIBLE IMAGERY ACROSS THE ENTIRE REGION AND MANY LOCATIONS UPSTREAM THIS SCENARIO OF THINNING SKIES LOOKS TO BE IN JEOPARDY. THUS HAVE CONCERNS ABOUT HOW COLD WE WILL SEE TEMPERATURES FALL TONIGHT. NONETHELESS 850MB THERMAL TROUGH CONTINUES TO PIVOT EAST...AND REMAIN OVERHEAD TONIGHT. AIDING IN TEMPERATURES FALLING INTO THE UPPER 20S TO LOWER 30S TONIGHT WILL BE THE STEADY COLD AIR ADVECTION WITH NORTHERLY WINDS TURNING NORHTEASTERLY. WITH AN INCREASING THERMAL DIFFERENTIAL ACROSS THE RELATIVELY WARMER MARINE ENVIRONMENT...AND MUCH COOLER AIR ALOFT EXPECT A NARROW CHANNEL OF LAKE MOISTURE TO FORM FROM THE NORTH/NORTHEAST WINDS. THIS WILL AID IN THE POSSIBILITY OF LAKE EFFECT FLURRIES/LGT SN. THEN BECOMING MIXED WITH LGT RA AFTER DAYBREAK MON. THROWING A POTENTIAL MONKEY WRENCH IN THIS SCENARIO COULD BE THE DEPTH OF THE FAVORED DENDRITIC GROWTH ZONE AND MOISTURE. VERY MINIMAL VERTICAL ENERGY MAY LIMIT THIS TO POSSIBLY JUST SOME DRIZZLE. THIS WILL BE THE FIRST CHALLENGE OF THE EVENING FORECAST. AS THIS COULD END UP BEING FROZEN DRIZZLE WITH TEMPERATURES POSSIBLY IN THE LOWER 30S. BEACHLER && .PREV DISCUSSION... 340 AM CST HIGHLIGHTS THIS WEEK WILL INCLUDE RAIN COMING TO AN END...POSSIBLE SN/RASN/RA ACROSS THE SOUTHEAST MONDAY...LES POTENTIAL FOR LAKE/COOK LATE SUNDAY NIGHT INTO MONDAY...TRANSITIONING SOUTH TO LAKE/PORTER INDIANA BY TUESDAY...A FEW DAYS OF QUIET...FOLLOWED BY A LATE CLIPPER AND SNOW POTENTIAL AND FINALLY A BLAST OF COLD BY NEXT WEEKEND. THE EARLY MORNING SURFACE MAP SHOWED THE SURFACE LOW THAT HAS BEEN BRINGING THE WET AND ACTIVE WEATHER TO THE AREA TODAY...CONTINUING TO LIFTING NORTH THROUGH CENTRAL WISCONSIN. MEANWHILE AN ATTENDANT COLD FRONT LAY ROUGHLY ACROSS THE MISSISSIPPI RIVER...SOUTHWEST NEARLY TO ST LOUIS. THIS FRONT WILL CONTINUE TO SLOWLY SWEEP FROM WEST TO EAST THIS MORNING EVENTUALLY PUSHING ITSELF AND THE PRECIP EAST. THE MOST WIDE SPREAD ECHOES HAVE PUSHED EAST AND ONLY A FEW SCATTERED SHOWERS ARE LOCATED WITH THE ACTUAL FRONT. ACROSS EAST CENTRAL IOWA...TEMPERATURES HAVE DROPPED ENOUGH THAT -SN WAS REPORTED...BUT CLOUD TOPS HAVE WARMED ENOUGH AND ARE WARMER THAN -10C. THIS MEANS THAT THERE IS NO LONGER ICE INTRODUCTION INTO THE SATURATED LAYERS BELOW...AND A FEW LOCATIONS REPORTED U.P. AND OR FZDZ. FOR OUR AREA...AFTER THE FRONT MOVES THROUGH...LOWER LEVEL MOISTURE WILL REMAIN BUT PROFILES ARE STILL INDICATIVE OF LIQUID PRECIP AND SURFACE TEMPS WILL REMAIN ABOVE FREEZING. THE HRRR AND RUC BOTH HAVE A GOOD HANDLE ON THE WESTERN EDGE OF THE PRECIP AND FRONTAL LOCATION...AND MOST OF IT SHOULD CLEAR THE ROCKFORD CORRIDOR NEAR SUNRISE...WITH CHICAGO AND EAST JUST A FEW HOURS BEYOND. WHILE LOWER LEVEL RH WILL REMAIN PREVALENT WITH AND SHORTLY BEYOND FROPA...MOISTURE ABOVE -10C WILL DISAPPEAR AND THERE MAY BE SOME LINGERING DZ INTO THE EARLY MORNING HOURS. THE BIG PUSH OF COLDER AIR ISNT EXPECTED UNTIL LATER THIS EVENING AND TEMPERATURES WILL REMAIN ABOVE FREEZING...SO NO CONCERN OVER ANY OTHER PRECIP TYPES THIS MORNING. HIGH TEMPS WILL GENERALLY BE SEEN EARLY TODAY...AND SLOWLY FALL THROUGH THE DAY. WINDS WILL ABATE AS HIGH PRESSURE AND A PERIOD OF DRY...SLOWLY MOVE IN. THE MAIN UPPER LEVEL TROUGHING THAT STRETCHES FROM ROUGHLY SASKATCHEWAN...SOUTHWEST THROUGH THE FOUR CORNERS REGION WILL NOT HAVE MUCH REASON TO MOVE UNTIL THE START OF THE WORKWEEK. PRESENT SHORTWAVE SEEN ON WATER VAPOR IMAGERY ROUNDING THE BASE OF THE TROUGH...ACROSS SOUTHERN ARIZONA...WILL DAMPEN SOME AS IT GETS EJECTED ON THE EASTERN FLANK TODAY AND TONIGHT. AS IT DOES THIS...IT WILL HELP TO AMPLIFY AN INVERTED TROUGH THAT WILL NOSE ITS WAY TOWARDS THE OHIO VALLEY...EVENTUALLY SPAWNING A WEAK LOW ACROSS THE TENNESSEE VALLEY. GUIDANCE HAS BEEN HEMMING AND HAWING WITH JUST HOW FAR NORTH TO BRING THE PRECIP WITH THIS FEATURE...AND JUST HOW MUCH OF IT WILL REACH INTO THE SOUTHEASTERN CORNER OF THE CWA. THE LATEST FORECAST TRENDS HAVE BACKED OFF FROM PREVIOUS...AND DID SCALE BACK ON POPS AS WELL AS COVERAGE. STILL A LITTLE UNCERTAIN WITH WHERE THE RASN VS STRAIGHT RA LINE WOULD BE AND WILL MAINTAIN A SORT OF MIX. ALSO OF NOTE FOR COASTAL LOCATIONS IN THIS SAME TIME FRAME /AS THE INV TROF-LOW SLIDE EAST/ IS THE CHANCE FOR LES. THERMAL PROFILES ACROSS THE SOUTHERN LAKE WILL BECOME INCREASINGLY UNSTABLE WITH LAKE SURFACE TO H85 DELTA T`S REACHING THE 12-15C RANGE. EXPECT WEAK SHOWERS TO BEGIN TO STRETCH FROM LAKE COUNTY IL...EVENTUALLY SOUTH TO COOK AND GRADUALLY INTO THE MORE TYPICAL LAKE/PORTER IN ORIENTATION. QPF AMOUNTS NOT LOOKING VERY IMPRESSIVE DURING THE SHORT DURATION AND WOULD ONLY EXPECT ANYWHERE FROM A TRACE TO MAYBE A TENTH OR TWO OF ACCUMULATION CLOSE TO THE LAKE TOMORROW AND INTO TOMORROW NIGHT. THIS WILL ALL BE FOLLOWED BY A FEW DAYS OF QUIET AS ANOTHER RIDGE OF HIGH PRESSURE SWINGS IN FROM THE NORTHWEST. A LATE WEEK SYSTEM IS STILL PART OF A LOW CONFIDENCE FORECAST. GFS HAD BEEN ADVERTISING A WEAK CLIPPER DROPPING FROM THE NORTHERN PLAINS... AND PREVIOUS EC SOLNS HAD SIMILAR...BUT THE 12Z FLIPPED AND DEVELOPED A SURFACE LOW THAT LIFTS THROUGH THE MISSISSIPPI VALLEY...INTO NORTHERN INDIANA...NORTHEAST THROUGH EASTERN ONTARIO. CONFIDENCE AT THIS POINT ON THAT EURO SOLN IS LOW AND WILL KEEP THE CHANCE OF SNOW AND NOT BUMP UP (OR DOWN) ANY CATEGORY UNTIL THE PICTURE IS A LITTLE CLEARER. THE 00Z SOLN BEGAN TO COME IN AND WAS BACK TO THE ORIGINAL PICTURE WITH THE CLIPPER RACING THROUGH. DESPITE THE LOWER CONFIDENCE IN THAT FEATURE LATE THIS WEEK...THE ONE PICTURE OF CLARITY WHAT WILL FOLLOW IT. ALL LONG RANGE GUIDANCE IS STILL INDICATING THAT THERE WILL BE A LARGE SURGE OF COLD AIR ENCROACHING AS AN UPPER LEVEL TROUGH SWINGS THROUGH. THERE ARE STILL SOME TIMING DIFFERENCES WITH HOW QUICKLY THE COLD AIR WILL DUMP IN...WHICH IS DUE IN PART TO THE LARGE MODEL DIFFERENCES MENTIONED MOMENTS AGO...BUT THE ONE THING THEY ALL AGREE ON IS HOW COLD THE LOWER LEVELS WILL GET INTO THE WEEKEND. EVEN A WEEK OUT...THE EC/GFS/GEFS/DGEX/GEM(NHEM THROUGH F144) ALL HIGHLIGHT H85 TEMPS PLUMMETING TO -16 TO -18 DEGREES...OR EVEN A FEW DEGREES COLDER. TRANSLATE THAT TO THE SURFACE AND IT WOULD BE POSSIBLE THAT HIGHS WOULD STRUGGLE TO GET OUT OF THE TEENS FOR MANY LOCATIONS AND OVERNIGHT LOWS LEADING INTO THE WEEKEND WOULD DIVE BOMB TO THE SINGLE DIGITS /BUT LIKELY A SMIDGEN WARMER IN THE CHICAGO METRO/. WITH THAT FORECAST STILL BEING OUT 6-7 DAYS...AND A SLEW OF OTHER WEATHER GOING ON THROUGH THE EARLY WEEK... WILL ONLY CONTINUE TO TREND DOWN FROM THE INHERITED LONG RANGE FORECAST. THE BIG SAVING GRACE IS THE LACK OF SOLID SNOW PACK. IF THAT WERE PRESENT...IT WOULD BE MUCH COLDER. SHEA && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * LOW MVFR TO IFR POST FRONTAL CIGS MOVING BACK ACROSS THE TERMINALS LATER THIS MORNING. KJB //DISCUSSION...UPDATED 12Z... LOW PRESSURE OVER NORTHERN LAKE MICHIGAN MOVING QUICKLY NORTHEAST THIS MORNING. MOST OF THE RAIN HAS MOVED OUT OF THE AREA. ONLY A FEW LIGHT SHOWERS REMAIN ALONG THE COLD FRONT...WHICH STRETCHES FROM THE LOW TO JUST WEST OF RFD TO STL. JUST KEPT A VCSH IN FOR A FEW HOURS TO COVER A POSSIBLE BRIEF LIGHT SHOWER THROUGH MID MORNING. STRONG SSW WINDS STILL GUSTING TO AROUND 25 KTS EARLY THIS MORNING. WINDS WILL SHIFT WEST WITH COLD FRONTAL PASSAGE MID MORNING AND DIMINISH. MAY STILL SEE SOME GUSTS TO AROUND 20 KT OR SO THROUGH MIDDAY. WINDS WILL BECOME NORTHWEST AND FALL TO LESS THAN 10 KT BY LATE AFTERNOON. MAIN ISSUE TODAY WILL BE LOW CEILINGS...PRESENTLY RUNNING AROUND 1000-1500 FT. SOME IFR NOTED OVER IA AND WESTERN IL BEHIND THE COLD FRONT. BUT WITH EVERYTHING LIFTING NORTHEAST...AND LOOKING AT MODEL SOUNDINGS...DONT EXPECT IFR CIGS TO IMPACT THE CHICAGO AREA TERMINALS. RFD MY FLIRT WITH IFR THROUGH THE MORNING HOURS AND HAVE COVERED THIS WITH A TEMPO GROUP. SHOULD SEE AN IMPROVING TREND THROUGH THE AFTERNOON. THE BACK EDGE OF THE STRATUS OVER THE DAKOTAS...NEB...INTO NW MO IS PUSHING EAST ON SATELLITE IMAGERY. THERE IS A POSSIBILITY OF STRATUS SCATTERING OUT OVER NORTHERN IL TOWARDS EVENING OR OVERNIGHT...BUT CONFIDENCE IN THAT HAPPENING IS LOW AND WILL HANG ON TO MVFR CIGS THROUGH THE NIGHT AT THIS POINT. WINDS WILL GRADUALLY VEER NORTH NORTHEAST LATE TONIGHT INTO MONDAY MORNING. AS COLDER AIR MOVES DOWN THE LAKE...SOME LAKE EFFECT CLOUDS AND LIGHT SNOW SHOWERS ARE POSSIBLE MONDAY BUT AT THIS TIME IT APPEARS THE CLOUD DEPTH WILL BE TOO SHALLOW TO SUPPORT ANY SIGNIFICANT LAKE EFFECT FOR MONDAY. ALLSOPP //ORD AND MDW CONFIDENCE...UPDATED 14Z... * HIGH CONFIDENCE IN MVFR CIGS. * LOW CONFIDENCE IN CIGS DROPPING INTO THE IFR CATEGORY. KJB //OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z... MONDAY NIGHT...MVFR CIG. CHANCE LIGHT LAKE EFFECT SNOW SHOWERS. TUESDAY...VFR. WEDNESDAY...VFR. THURSDAY...VFR. FRIDAY...VFR. SATURDAY...VFR. ALLSOPP && .MARINE... 133 AM CST A POWERFUL STORM WAS MOVING THROUGH THE GREAT LAKES THIS MORNING. LOW PRESSURE WILL MOVE QUICKLY FROM WISCONSIN TO NORTHERN LAKE MICHIGAN THIS MORNING...THEN ON TO QUEBEC BY EVENING. EAST OF THE TRACK OF THE LOW A VERY STRONG SOUTHERLY LOW LEVEL JET WAS OCCURRING...WITH 50 KT WINDS JUST 1 TO 2 THOUSAND FEET OFF THE SURFACE. A STRONG INVERSION WAS LIMITING MIXING BUT GALE FORCE WINDS WERE WORKING DOWN TO THE LAKE SURFACE OVER THE SOUTH HALF WITH SOME GALE FORCE GUSTS ON THE EAST SIDE OF THE NORTH HALF OF THE LAKE. WINDS SHOULD DROP OFF PRETTY QUICKLY AS THE LOW MOVES RAPIDLY NORTHEAST TODAY AND GALES SHOULD END BY ABOUT NOON. PRESENTLY GALE WARNING GOES THROUGH MID AFTERNOON BUT IT MAY BE CANCELED EARLY. WINDS WILL VEER FROM SOUTH TO NORTHWEST THROUGH THE COURSE OF THE DAY. TONIGHT THROUGH MONDAY ANOTHER LOW WILL MOVE FROM THE TEXAS COAST UP THROUGH THE OHIO VALLEY WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. THIS WILL PRODUCE A PERIOD OF NORTHERLY WINDS ON LAKE MICHIGAN. THE REST OF THE WEEK HIGH PRESSURE WILL DOMINATE THE CENTRAL U.S. WHILE LOW PRESSURE BECOMES ANCHORED OVER NORTHEAST CANADA. THIS WILL PRODUCE A PROLONGED PERIOD OF WESTERLY WINDS OVER LAKE MICHIGAN FROM MID WEEK INTO THE WEEKEND. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 PM SUNDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
547 PM EST SUN DEC 4 2011 .SYNOPSIS... WITH HIGH PRESSURE EAST OF THE REGION OUR ATTENTION TURNS TO A SLOW MOVING FRONTAL SYSTEM APPROACHING PENNSYLVANIA. CLOUDS FROM THIS FRONT WILL OVERSPREAD TONIGHT. ON MONDAY RAINFALL WILL INCREASE IN COVERAGE AND INTENSITY OVER THE WEST AND SPREAD ACROSS CENTRAL PENNSYLVANIA OVERNIGHT. TEMPERATURES WILL CONTINUE WELL ABOVE AVERAGE WITH THIS SYSTEM...UNTIL A STRONG COLD FRONT BRING TEMPERATURES BACK DOWN TO AVERAGE READINGS LATE TUESDAY AND WEDNESDAY. ANOTHER STORM SYSTEM WILL APPROACH THE REGION FROM THE SOUTH ON THURSDAY. THIS STORM HAS THE POTENTIAL TO BRING SOME WINTRY OR MIXED PRECIPITATION DEPENDING ON THE TRACK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... TRANQUIL WEATHER WILL PERSIST OVERNIGHT ACROSS MOST OF THE REGION WITH JUST AREAS OF MAINLY CIRROSTRATUS...AND SOME HIGH-BASED ALTO CU DRIFTING NE. 15Z SREF AND 21Z RUC SHOWS SOME LIGHT SHOWERS EDGING INTO WARREN AND PERHAPS ELK/MCKEAN COUNTIES AFTER 07Z. EVEN THERE...QPF WILL BE LIGHT AND LESS THAN 0.10 BY 12Z MONDAY. VERY MILD TEMPS FOR EARLY DECEMBER WILL CONTINUE THROUGH TONIGHT. THANKS TO THE GENERALLY LIGHT SOUTHERLY BREEZE...AND FAIR AMOUNT OF CLOUD COVER...TEMPS WILL ONLY REACH THE UPPER 30S TO LOWER 40S FOR MINS /WHICH WILL BE 10-15F ABOVE NORMAL...WITH THE GREATEST DEPARTURES OCCURRING ACROSS THE MOUNTAINS/. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... CLOUDS LOWER AND THICKEN AS FRONTAL BOUNDARY APPROACHES. PRECIPITATION WILL INCREASE IN THE AFTERNOON HOURS AND BECOME A STEADY LIGHT RAIN OVERNIGHT. FRONT STILL WEST OF AREA SO MILD TEMPERATURES CONTINUE THROUGH THE PERIOD. && .LONG TERM /TUESDAY THROUGH SUNDAY/... MODELS AGREE ON A COLD FRONT PUSHING ACROSS PA ON TUE...KEEPING RAIN CHANCES HIGH...ESPECIALLY ACROSS THE SOUTHERN MTNS AND SUSQ VALLEY. TEMPS TUE START OFF MILD...BUT WILL LIKELY REMAIN STEADY OR FALL A BIT IN THE AFTERNOON...ESP IN THE NW. NO LARGE PUSH OF COLD AIR BEHIND FRONT EVIDENT THOUGH. LINGERING CHANCE FOR LIGHT RAIN/SNOW SHOWERS TUE NIGHT INTO WED AS NARROW TROUGH AND COOLER AIR SLIDES OVERHEAD. MUCH UNCERTAINTY IN LATE WEEK SOLUTIONS AS LARGE MODEL DIVERGENCE CONTINUES. WAVE OF LOW PRESSURE SLIDES UP/EAST OF THE APPALACHIANS THU...WITH ECMWF CONTINUING TO TRACK THIS TO OUR SE...THOUGH THE GFS SOLUTION CONTINUES TO BECOME GRADUALLY MORE INTERESTING WITH A MORE NORTHERLY TRACK. TOUGH TO RESOLVE THIS IN THE GRIDS OTHER THAN TO EDGE POPS UPWARD A BIT ON THU AND SEE HOW THIS PLAYS OUT. COULD BRING POTENTIAL FOR 0.50 INCH QPF...WITH SOME OF THAT FALLING AS SNOW IF THE GFS SOLUTION WINS OUT...THOUGH AM STILL LEANING MORE TOWARD THE ECMWF SOLUTION AT THIS TIME. TROUGH DIGS IN FROM THE NW FRI NIGHT INTO SAT...BRINGING NOTICABLY COLDER TEMPS AND WESTERLY FLOW. THIS WILL ALSO BRING A GOOD CHANCE FOR LAKE EFFECT SNOW SHOWERS IN THE NW MTNS SAT. TEMPS SHOULD BEGIN TO REBOUND EARLY NEXT WEEK. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... SOME ISOLATED PRE-FRONTAL SHOWERS MAY MOVE INTO BFD EARLY TOMORROW MORNING...ALONG WITH SOME MVFR VSBYS. CALM WINDS AND LOW LEVEL MOISTURE WILL ALLOW FOR FOG FORMATION ACROSS THE SUSQ VALLEY OVERNIGHT. LATEST MDL DATA SUGGEST IFR VSBYS ARE LIKELY AT IPT/MDT/LNS LATE TONIGHT. FOG OVER THE SUSQ VALLEY SHOULD DISSIPATE BY MIDDAY MONDAY. OUTLOOK... MON...RAIN/LOW CIGS POSSIBLE...MAINLY NW. TUE...RAIN/LOW CIGS POSSIBLE. WED...RAIN AREA WIDE TRANSITIONS TO SHSN NW. THU...LOW CIGS...SHSN NW. FRI...LOW CIGS/LAKE EFFECT SHOWERS POSSIBLE MAINLY NW. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...ROSS/LAMBERT NEAR TERM...LAMBERT SHORT TERM...ROSS/LAMBERT LONG TERM...RXR AVIATION...FITZGERALD/KREKELER
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
519 PM EST SUN DEC 4 2011 .SYNOPSIS... WITH HIGH PRESSURE EAST OF THE REGION OUR ATTENTION TURNS TO A SLOW MOVING FRONTAL SYSTEM APPROACHING PENNSYLVANIA. CLOUDS FROM THIS FRONT WILL OVERSPREAD TONIGHT. ON MONDAY RAINFALL WILL INCREASE IN COVERAGE AND INTENSITY OVER THE WEST AND SPREAD ACROSS CENTRAL PENNSYLVANIA OVERNIGHT. TEMPERATURES WILL CONTINUE WELL ABOVE AVERAGE WITH THIS SYSTEM...UNTIL A STRONG COLD FRONT BRING TEMPERATURES BACK DOWN TO AVERAGE READINGS LATE TUESDAY AND WEDNESDAY. ANOTHER STORM SYSTEM WILL APPROACH THE REGION FROM THE SOUTH ON THURSDAY. THIS STORM HAS THE POTENTIAL TO BRING SOME WINTRY OR MIXED PRECIPITATION DEPENDING ON THE TRACK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... TRANQUIL WEATHER WILL PERSIST OVERNIGHT ACROSS MOST OF THE REGION WITH JUST AREAS OF MAINLY CIRROSTRATUS...AND SOME HIGH-BASED ALTO CU DRIFTING NE. 15Z SREF AND 21Z RUC SHOWS SOME LIGHT SHOWERS EDGING INTO WARREN AND PERHAPS ELK/MCKEAN COUNTIES AFTER 07Z. EVEN THERE...QPF WILL BE LIGHT AND LESS THAN 0.10 BY 12Z MONDAY. VERY MILD TEMPS FOR EARLY DECEMBER WILL CONTINUE THROUGH TONIGHT. THANKS TO THE GENERALLY LIGHT SOUTHERLY BREEZE...AND FAIR AMOUNT OF CLOUD COVER...TEMPS WILL ONLY REACH THE UPPER 30S TO LOWER 40S FOR MINS /WHICH WILL BE 10-15F ABOVE NORMAL...WITH THE GREATEST DEPARTURES OCCURRING ACROSS THE MOUNTAINS/. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... CLOUDS LOWER AND THICKEN AS FRONTAL BOUNDARY APPROACHES. PRECIPITATION WILL INCREASE IN THE AFTERNOON HOURS AND BECOME A STEADY LIGHT RAIN OVERNIGHT. FRONT STILL WEST OF AREA SO MILD TEMPERATURES CONTINUE THROUGH THE PERIOD. && .LONG TERM /TUESDAY THROUGH SUNDAY/... MODELS AGREE ON A COLD FRONT PUSHING ACROSS PA ON TUE...KEEPING RAIN CHANCES HIGH...ESPECIALLY ACROSS THE SOUTHERN MTNS AND SUSQ VALLEY. TEMPS TUE START OFF MILD...BUT WILL LIKELY REMAIN STEADY OR FALL A BIT IN THE AFTERNOON...ESP IN THE NW. NO LARGE PUSH OF COLD AIR BEHIND FRONT EVIDENT THOUGH. LINGERING CHANCE FOR LIGHT RAIN/SNOW SHOWERS TUE NIGHT INTO WED AS NARROW TROUGH AND COOLER AIR SLIDES OVERHEAD. MUCH UNCERTAINTY IN LATE WEEK SOLUTIONS AS LARGE MODEL DIVERGENCE CONTINUES. WAVE OF LOW PRESSURE SLIDES UP/EAST OF THE APPALACHIANS THU...WITH ECMWF CONTINUING TO TRACK THIS TO OUR SE...THOUGH THE GFS SOLUTION CONTINUES TO BECOME GRADUALLY MORE INTERESTING WITH A MORE NORTHERLY TRACK. TOUGH TO RESOLVE THIS IN THE GRIDS OTHER THAN TO EDGE POPS UPWARD A BIT ON THU AND SEE HOW THIS PLAYS OUT. COULD BRING POTENTIAL FOR 0.50 INCH QPF...WITH SOME OF THAT FALLING AS SNOW IF THE GFS SOLUTION WINS OUT...THOUGH AM STILL LEANING MORE TOWARD THE ECMWF SOLUTION AT THIS TIME. TROUGH DIGS IN FROM THE NW FRI NIGHT INTO SAT...BRINGING NOTICABLY COLDER TEMPS AND WESTERLY FLOW. THIS WILL ALSO BRING A GOOD CHANCE FOR LAKE EFFECT SNOW SHOWERS IN THE NW MTNS SAT. TEMPS SHOULD BEGIN TO REBOUND EARLY NEXT WEEK. && .AVIATION /22Z SUNDAY THROUGH FRIDAY/... LLWS IS POSSIBLE OVER BFD EARLY THIS AFTERNOON...MAINLY OVER THE NW MTNS. SOME ISOLATED PRE-FRONTAL SHOWERS MAY MOVE INTO BFD EARLY TOMORROW MORNING...ALONG WITH SOME MVFR VSBYS. CALM WINDS AND LOW LEVEL MOISTURE WILL ALLOW FOR MVFR CONDITIONS ALONG THE LOWER SUSQ TOMORROW MORNING. THESE CONDITIONS SHOULD CONTINUE UNTIL 15Z BEFORE LIFTING. OUTLOOK... MON...RAIN/LOW CIGS POSSIBLE...MAINLY NW. TUE...RAIN/LOW CIGS POSSIBLE. WED...RAIN AREA WIDE TRANSITIONS TO SHSN NW. THU...LOW CIGS...SHSN NW. FRI...LOW CIGS/LAKE EFFECT SHOWERS POSSIBLE MAINLY NW. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...ROSS/LAMBERT NEAR TERM...LAMBERT SHORT TERM...ROSS/LAMBERT LONG TERM...RXR AVIATION...KREKELER
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1020 AM CST SUN DEC 4 2011 .DISCUSSION... STRATUS SLOW TO EXIT THIS MORNING SO HAVE SLOWED THE EASTWARD PROGRESSION. THIS OF COURSE ALSO MEANS A LITTLE SLOWER RISE IN TEMPERATURES IN THESE AREAS WHICH WILL MEAN TEMPERATURES STUCK IN THE LOWER TO MID 20S. NOT MUCH WIND TO SPEAK OF FOR THE NEXT SEVERAL HOURS HOWEVER SO NOT QUITE AS COLD AS IT COULD BE. LOW PRESSURE IS DEVELOPING ACROSS THE WESTERN HIGH PLAINS AND WILL MOVE ACROSS SOUTH DAKOTA THROUGH THE NIGHT. THIS WILL BRING A STRONG NORTH TO NORTHWEST WIND TONIGHT WHICH WILL CARRY INTO TOMORROW. OTHERWISE...A WEAK THERMAL/THETA E RIDGE IN THE LOW AND MID LEVELS WILL SPREAD INTO CENTRAL SOUTH DAKOTA LATE THIS AFTERNOON AND EARLY THIS EVENING ALONG WITH WEAK PV ADVECTION ALOFT SO WILL NEED TO WATCH THIS AREA FOR A LITTLE LIGHT SNOW FROM ABOUT 6 PM THROUGH 2 AM. WILL HAVE TO OVERCOME QUITE A BIT OF DRY AIR IN THE WAKE OF YESTERDAYS SYSTEM SO CONFIDENCE NOT EXCEEDINGLY HIGH ON ACCUMULATIONS. THINKING THAT THE BETTER CHANCES FOR ACCUMULATIONS WILL BE TONIGHT AND MORE COUPLED WITH FORCING FROM ABOUT 850-800MB WHERE THE BETTER DENDRITIC LAYER RESIDES. WHILE LAYERS ABOVE...ESPECIALLY FROM ABOUT 700MB ON UP...WILL BE QUITE DRY WE SHOULD BE STILL GET A LITTLE LIGHT SNOW WITH THE FAVORABLE FORCING/THERMAL FIELDS IN THE LOW LEVELS. /08 && .AVIATION.../FOR THE 18Z TAF ISSUANCE/ LARGE AREA OF MVFR STRATUS SLOWLY SHIFTING EAST THIS MORNING...BUT THE WESTERN EDGE FINALLY STARTING TO SHOW SIGNS OF DISSIPATION. WILL KEEP FSD AND SUX WITHIN THE STRATUS THROUGH ABOUT 18-20Z THEN EXPECTING MAINLY MID AND HIGH CLOUDS...VFR...THROUGH THE PERIOD. HON WILLS SEE THE BEST CHANCE FOR A RETURN OF MVFR CEILINGS AFTER ABOUT 10Z AS COLDER AIR SURGES SOUTHWARD. SOME PATCHY LIGHT SNOW...MAINLY VFR BUT SOME PATCHY MVFR...WILL ALSO BE POSSIBLE FROM ABOUT THE JAMES VALLEY WEST WITH THE BETTER CHANCE FROM ABOUT 2Z THROUGH 10Z. /08 && .PREV DISCUSSION.../ISSUED AT 311 AM CST/ LIGHT SNOW WHICH AFFECTED PORTIONS OF OUR AREA ON SATURDAY HAS PUSHED INTO CENTRAL MINNESOTA AND CENTRAL IOWA VERY EARLY THIS MORNING. BEHIND THE EXITING SYSTEM...A BROAD AREA OF STRATUS HAS DEVELOPED ACROSS THE EASTERN DAKOTAS INTO EASTERN NEBRASKA...THOUGH MODELS NOT PICKING UP ON THIS AT ALL. 06Z RUC 925 MB RH TIME SECTION HINTING AT IT...AND HAS IT PULLING EASTWARD THROUGH THE MORNING...EXITING OVER OUR FAR EAST BY 18Z. OTHERWISE...A RELATIVELY QUIET DAY IN STORE...WITH CLOUDS INCREASING IN OUR WEST IN THE AFTERNOON AS A WEAK SHORTWAVE DROPS SOUTHWARD ON A NORTHWESTERLY UPPER LEVEL FLOW. NOT MUCH IN THE WAY OF DYNAMICS WITH THIS FEATURE...BUT COULD SPIT OUT SOME VERY LIGHT SNOW IN OUR WEST BY LATE THIS AFTERNOON INTO TONIGHT. TEMPERATURES A BIT TRICKY TODAY IN BETWEEN CLOUD COVER...THOUGH WHAT IS MORE CERTAIN IS THAT READINGS WILL NOT WARM A WHOLE LOT OVER SNOW COVERED AREAS...WITH HIGHS GENERALLY IN THE MID 20S THROUGH NORTHWESTERN IOWA AND PORTIONS OF SOUTHWESTERN MINNESOTA. TO THE WEST...WITH MORE SUN AND BETTER MIXING IN A TRANSITIONING SOUTHWESTERLY LOW LEVEL FLOW...HIGHS WILL REACH THE MID 30S ACROSS THE MUCH OF THE JAMES RIVER VALLEY INTO SOUTH CENTRAL SOUTH DAKOTA. WINDS WILL BECOME NORTHWESTERLY AND PICK UP FROM WEST TO EAST TONIGHT IN A TIGHTENING GRADIENT AND COLD AIR ADVECTION BEHIND THE EXITING SHORTWAVE AND SURFACE LOW/ASSOCIATED FRONTAL BOUNDARY. THE WINDS AND CLOUD COVER WILL KEEP OVERNIGHT LOWS SOMEWHAT IN CHECK...THOUGH WILL STILL DROP INTO THE TEENS...EXCEPT SINGLE DIGITS OVER SNOW COVER. COLDER AIR WILL CONTINUE TO FILTER INTO THE REGION ON MONDAY WITH A SURFACE HIGH BUILDING INTO THE REGION. TEMPERATURES WILL NOT RISE MUCH FROM EARLY MORNING LOWS...WITH HIGHS ONLY IN THE UPPER TEENS TO LOWER 20S. SOUTHERLY FLOW RETURNS TO THE REGION ON TUESDAY BEHIND THE EXITING HIGH...AND TEMPERATURES TRY TO WARM A BIT IN THE WEST...INTO THE MID AND UPPER 20S...WHILE READINGS OVER SNOW COVERED AREAS MAY ACTUALLY BE A LITTLE COOLER THAN MONDAYS HIGHS WITH LESS MIXING...REMAINING ONLY IN THE UPPER TEENS. EVEN WARMER ON WEDNESDAY AHEAD OF THE NEXT ARCTIC SURGE WHICH WILL DIVE SOUTHWARD ON WEDNESDAY NIGHT AND THURSDAY. COULD GET A LITTLE SNOW ALONG THE LEADING EDGE OF THIS SURGE/FRONTAL GRADIENT DURING THAT TIME FRAME...THOUGH ANY SNOW SHOULD BE LIGHT. HIGHS ON WEDNESDAY WILL BE IN THE UPPER 20S TO MID 30S...THEN DROP BACK TO THE LOWER TO MID 20S ON THURSDAY. FRIDAY LOOKS TO BE THE COLDEST DAY OF THE WEEK...WITH HIGHS MID TEENS TO AROUND 20...FOLLOWED BY SOME WARMING ON SATURDAY. LOOKS TO REMAIN DRY BOTH DAYS. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. && $$
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
244 PM CST SUN DEC 4 2011 ...A BRIEF TRANSITION TO A WINTRY MIX POSSIBLE FAR NORTHWEST LATE TONIGHT EARLY MONDAY...OTHERWISE JUST A COLD RAIN EXPECTED... .DISCUSSION... WIDESPREAD LIGHT TO MODERATE RAIN WITH ISOLATED/EMBEDDED THUNDERSTORMS ARE CONTINUING THIS AFTERNOON SOUTHEAST OF A CISCO TO DECATUR...TO GAINESVILLE LINE. MAIN DRIVING FORCE HAS BEEN WARM ADVECTION/ISENTROPIC LIFT OVER A SHALLOW FRONTAL INVERSION CURRENTLY OVER NORTH TEXAS. WILL CONTINUE THE HIGH RAIN CHANCES ACROSS THE MAJORITY OF NORTH TEXAS TONIGHT AS THE NEXT STRONG SHORTWAVE BEGINS TO APPROACH NORTH TEXAS. MODERATE RAIN IS OCCURRING ACROSS THE EASTERN COUNTIES AND 1 TO 2 INCHES..WITH LOCALIZED AMOUNTS ACROSS NORTHEAST COUNTIES POSSIBLY NEARING 3 INCHES...IS EXPECTED THROUGH MONDAY MORNING. THE 850MB FRONT IS CURRENTLY SITUATED FROM NEAR LUBBOCK TO OKLAHOMA CITY THIS AFTERNOON AND SHOULD PROGRESS SOUTHWARD..REACHING OUR NORTHWEST COUNTIES BY DAYBREAK MONDAY MORNING PER THE WRF AND HRRR MODELS. MODEL FORECAST SOUNDINGS FOR THIS AREA HAVE SATURATION AT/ABOVE 800MB WITH THE THERMAL PROFILE STRADDLING THE 0 DEG C ISOTHERM THROUGH THE MORNING HOURS MONDAY. BOTH MODELS SHOW SOME DRY POCKETS...PARTICULARLY BELOW 850MB WHICH SHOULD KEEP ANY PRECIPITATION VERY LIGHT WITH A VERY LIGHT RAIN/SNOW MIX POSSIBLE. THE SHORTWAVE DISTURBANCE PASSES EAST OF NORTH TEXAS MONDAY AFTERNOON WITH SUBSIDENCE AND ISENTROPIC DOWNGLIDE IN ITS WAKE. THIS PROCESS WILL RAPIDLY SHUT OFF MOST PRECIPITATION FROM WEST TO EAST THROUGH TUESDAY EVENING WITH BRISK AND COLD CONDITIONS CONTINUING THROUGH THE NIGHT TUESDAY. WITH THE POSITIVELY TILTED UPPER TROUGH TO OUR WEST...PLENTY OF MID-HIGH CLOUDINESS SHOULD REMAIN MONDAY NIGHT THROUGH WEDNESDAY MORNING. THE COMBINATION OF MOSTLY CLOUDY SKIES AND CONTINUED CAA IN THE LOWER LEVELS WILL MAINTAIN A COLD START TO THE FIRST HALF OF THE WEEK. STUBBORN UPPER LOW WILL OPEN AND LIFT OUT TUES NIGHT AND WEDNESDAY MORNING AS STRONG JET STREAK ROUNDS ITS BASE. MODELS SHOW SOME ELEVATED LIFT AND SHALLOW SATURATED LAYER ACROSS THE NORTHERN HALF OF NORTH TEXAS AS THE UPPER TROUGH LIFTS OUT. IT APPEARS A FEW FLURRIES COULD OCCUR CLOSER TO THE RED RIVER...BUT WILL LEAVE OUT FOR NOW UNTIL MOISTURE PROFILES ARE BETTER RESOLVED. IN WAKE OF OUR UPPER TROUGH...BRIEF MID LEVEL HEIGHT RISES OCCUR LATER WEDNESDAY INTO THURSDAY ALLOWING FOR A MOSTLY CLEAR FORECAST. CHILLY NIGHTS AND COOL DAYS WILL BE THE RULE LATE WEEK. ANOTHER REINFORCING COLD FRONT ARRIVES BY FRIDAY AND WILL KEEP THE AREA COOL INTO NEXT WEEKEND...AS ZONAL FLOW ALOFT PREVAILS. 05/42 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 38 42 32 40 28 / 100 60 10 10 10 WACO, TX 42 44 32 42 28 / 100 60 10 10 10 PARIS, TX 39 43 34 44 28 / 100 80 20 10 10 DENTON, TX 37 41 29 40 25 / 80 40 10 10 10 MCKINNEY, TX 38 42 31 42 26 / 100 60 10 10 10 DALLAS, TX 39 43 33 42 27 / 100 60 10 10 10 TERRELL, TX 40 43 31 43 28 / 100 80 10 10 10 CORSICANA, TX 41 44 35 44 30 / 100 70 10 10 10 TEMPLE, TX 41 43 32 43 28 / 100 60 10 10 10 MINERAL WELLS, TX 34 41 25 41 24 / 70 40 10 10 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 82/05/42
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
224 PM CST SUN DEC 4 2011 .SHORT TERM...TONIGHT AND MONDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A DOUBLE BARRELED LOW PRESSURE MOVING ACROSS THE ONTARIO-QUEBEC BORDER AND THE STRAITS OF MACKINAC...AND A COLD FRONT STRETCHING FROM NORTHERN LOWER MICHIGAN TO THE SOUTHERN MISSISSIPPI VALLEY. WITH NORTHWEST FLOW IN PLACE AND DELTA T/S INCREASING TO 14C...CLOUD COVER HAS BEEN STUBBORN TO DISSIPATE THOUGH PRECIP HAS EXITED TO THE NORTHEAST BY MIDDAY. A SURFACE TROUGH IS TRYING TO DEVELOP OVER NORTHEAST AND CENTRAL WISCONSIN THIS AFTERNOON AND A FEW SNOW SHOWERS/FLURRIES HAVE DEVELOPED OVER THE PAST HOUR. SOME CLEARING NOTED OVER NORTHERN MINNESOTA WHERE DEWPOINTS HAVE FALLEN TO THE LOWER TEENS. WITH NORTHERLY FLOW IN PLACE OVER THE NEXT 24 HOURS...SMALL PRECIP CHANCES AND CLOUD TRENDS ARE THE MAIN FORECAST CONCERNS. TONIGHT... AS HIGH PRESSURE BUILDS OVER THE NORTHERN PLAINS...WEAK CYCLONIC FLOW WILL LINGER ACROSS THE REGION. LOW LEVEL FLOW WILL VEER FROM THE NORTHWEST TO THE NORTH...WHICH WILL KEEP MOISTURE STREAMING OFF LAKE SUPERIOR. AS A RESULT...SCT LAKE EFFECT SNOW SHOWERS WILL PREVAIL OVER THE SNOW BELT OF N-C WISCONSIN FOR THE ENTIRE NIGHT. FARTHER SOUTH...A WEAK SURFACE TROUGH WILL MOVE SOUTH OVER CENTRAL WISCONSIN THIS EVENING. MOISTURE DEPTH WILL EXTEND BEYOND 800MB AND -10C...SO IT SEEMS PLAUSIBLE THAT FLURRIES OR VERY LIGHT SNOW SHOWERS ARE POSSIBLE ALONG THE TROUGH. HAVE ADDED SLIGHTLY MORE TEMPORAL RESOLUTION TO ACCOUNT FOR THIS. OTHERWISE...DO NOT SEE MUCH OF AN OPPORTUNITY FOR CLEARING...EXCEPT IN THE DOWN SLOPING REGIONS OF NORTHEAST WISCONSIN WHERE SOME HOLES MAY DEVELOP...ESPECIALLY LATE TONIGHT. LOWS IN THE UPPER TEENS NORTH TO UPPER 20S SOUTHEAST. MONDAY...ONLY SOME SUBTLE CHANGES HEADING INTO MONDAY. SHORTWAVE ENERGY OVER THE PLAINS WILL LIFT TO THE NORTHEAST OVER NW WISCONSIN...BUT WITH VERY LITTLE IMPACT ON OUR WEATHER. WILL CONTINUE TO HAVE NORTHERLY FLOW TOMORROW WITH SOME MINOR COLD ADVECTION THAT WILL DROP 850MB TEMPS IN THE NEGATIVE LOW TO MID TEENS. LIGHT LAKE EFFECT SNOW SHOWERS WILL PREVAIL OVER THE SNOW BELT OF N-C WISCONSIN...WHILE MOSTLY CLOUDY CONDITIONS WILL BE THE RULE ELSEWHERE. HIGHS IN THE MIDDLE 20S NORTH TO MIDDLE 30S SOUTHEAST. .LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY...THE MAIN FCST CONCERN IS THE ARRIVAL OF COLDER ARCTIC AIR LATE IN THE NEXT WORK WEEK. A STRONG UPPER RIDGE WILL COVER THE EASTERN PACIFIC...SOUTHWEST CANADA AND THE WEST COAST OF THE U.S. EARLY IN THE PERIOD...WITH A POSITIVELY-TILTED UPPER TROF MOVG OUT OF THE NORTHERN PLAINS INTO THE WESTERN GREAT LAKES. THIS UPPER TROF WILL MOVE THROUGH WISCONSIN ON MONDAY NIGHT AND TUESDAY...BUT WITH A SFC RIDGE OF HIGH PRESSURE IN PLACE...EXPECT MINIMAL IMPACT ON OUR WEATHER. SHORT-WAVE ENERGY TOPPING THE WESTERN RIDGE AND DIVING INTO THE NORTHERN PLAINS WILL HELP TO CARVE A BROAD TROF OVER THE CENTRAL U.S. BY THURSDAY. A SURGE OF ARCTIC AIR IS EXPECTED TO ARRIVE IN WI ON THURSDAY...WITH H8 TEMPS PLUMMETING TO AROUND -20 C LATE THURSDAY NIGHT INTO FRIDAY. THIS WILL LEAD TO OUR COLDEST TEMPERATURES SO FAR THIS SEASON. THE COLD SNAP WILL BE BRIEF... AS SOUTHWEST WINDS DEVELOP IN THE WAKE OF THE RETREATING ARCTIC HIGH OVER THE WEEKEND. A LARGE RIDGE OF HIGH PRESSURE WILL BUILD INTO NW WI ON MONDAY NIGHT...THEN MOVE THROUGH GRB CWA ON TUESDAY. LINGERING LAKE-EFFECT SNOW SHOWERS OVER NC WI SHOULD COME TO AN END AS THE RIDGE AXIS ARRIVES ON TUESDAY. A WEAK COLD FRONT IS EXPECTED TO MOVE THROUGH THE REGION ON WEDNESDAY...WITH A STRONGER ARCTIC FRONT ARRIVING ON THURSDAY. THE ECMWF HAS BACKED OFF ON THE POTENTIAL FOR SNOW ALONG THE ARCTIC FRONT ON THU NGT/FRI...AND IS FOCUSING FARTHER SE...FROM SOUTHERN WI INTO LOWER MICHIGAN. WILL NEED TO KEEP AN EYE ON THIS OVER THE NEXT FEW DAYS TO SEE IF THIS TREND WILL HOLD. CONFIDENCE IS FAIRLY HIGH FOR THE ARRIVAL OF MUCH COLDER TEMPERATURES LATE IN THE WORK WEEK...ALTHOUGH THE COLD IS EXPECTED TO BE SHORT-LIVED. A WARM FRONT IS EXPECTED TO ARRIVE ON SUNDAY...WITH TEMPERATURES CLIMBING BACK TO ABOVE NORMAL. DESPITE THE PRESENCE OF A COLD AIR MASS FROM WEDNESDAY THROUGH SATURDAY...WIND TRAJECTORIES WILL NOT BE FAVORABLE FOR LK-EFFECT SNOW. && .AVIATION...CYCLONIC FLOW VEERING FROM NORTHWEST TO NORTH WILL BE PREVAILING ACROSS THE REGION THROUGH TOMORROW. WITH FLOW OFF LAKE SUPERIOR...WILL BE HARD PRESSED TO SEE SOME CLEARING OVER THE TAF SITES. SOME HOLES WILL LIKELY DEVELOP OVER THE FOX VALLEY WITH TEMPORARY VFR CIGS...BUT MVFR CIGS WILL PREVAIL THROUGH LATE TONIGHT. SOME SNOW SHOWERS/FLURRIES WILL OCCASIONALLY IMPACT RHI...AND POSSIBLY AUW/CWA THIS EVENING WHEN A WEAK SURFACE TROUGH DROPS SOUTH. SOME MINOR IMPROVEMENT OF CIGS EXPECTED ON MONDAY. MPC && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ MPC/KIECKBUSCH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1141 AM CST SUN DEC 4 2011 .SHORT TERM...TODAY THROUGH TUESDAY NIGHT 324 AM CST SUN DEC 4 2011 MAIN FORECAST CONCERN NOW THAT THE PRECIPITATION IS EXITING/DIMINISHING IS WHEN CLOUDS WILL CLEAR. CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING STILL OVER THE EAST PACIFIC AND ALONG THE EAST COAST OF THE U.S....AND TROUGHING IN-BETWEEN FROM HUDSON BAY SOUTHWEST INTO ARIZONA. IMPORTANT FEATURES TO NOTE INCLUDE A SHORTWAVE NEAR EAU CLAIRE WI ON THE EAST SIDE OF THE UPPER TROUGH...AND TWO SHORTWAVES OVER MONTANA ON THE BACK SIDE OF THE UPPER TROUGH. THE FORMER SHORTWAVE IN CONJUNCTION WITH PLENTIFUL MOISTURE AND LOW TO MID-LEVEL FRONTOGENESIS BROUGHT THE WIDESPREAD PRECIPITATION TO THE AREA LAST NIGHT. DRY SLOT NOTED IN WATER VAPOR COMBINED NOW WITH THE SHORTWAVE MOVED THROUGH...RESULTING IN SOME SUBSIDENCE...HAS ALLOWED PRECIPITATION TO REALLY DIMINISH DURING THE PAST 4-6 HOURS. IT APPEARS MODELS YESTERDAY MAY HAVE OVERDONE THE LOW LEVEL ISENTROPIC LIFT FOR THE CURRENT EARLY MORNING HOURS... GIVEN THAT THEY NOW SHOW NO ISENTROPIC LIFT AND SEEING THE PRECIPITATION DIMINISH ON RADAR. THEREFORE...THE CONCERN ABOUT THE DRY SLOT CLEARING OUT ICE AND RESULTING IN FREEZING PRECIPITATION IS NOT AS GREAT. IN ADDITION... SURFACE TEMPERATURES HAVE STRUGGLED TO FALL BELOW FREEZING WHERE IR CLOUD TOP TEMPERATURES INDICATE ICE HAS BEEN LOST. REGARDING THE SURFACE...SEA LEVEL PRESSURE ANALYSIS SHOWS A 1008MB LOW NEAR MANITOWOC WI. PLENTY OF CLOUDS EXTEND WEST FROM THE LOW...BACK INTO THE EASTERN DAKOTAS. UPSTREAM...ANOTHER BUT MUCH WEAKER SURFACE LOW IS NOTED NEAR WILLISTON ASSOCIATED WITH ONE OF THE MONTANA SHORTWAVES. TODAY AND TONIGHT...A SHORTWAVE IN EASTERN MONTANA IS PROGGED TO MOVE INTO SOUTH DAKOTA TODAY AND INTO NORTHWEST WISCONSIN TONIGHT. THE TRACK OF THE SHORTWAVE SUGGESTS ALL OF THE FORCING WILL STAY NORTH AND WEST OF THE AREA. THIS IS CONFIRMED TOO BY QG PLOTS. IN ADDITION...IT APPEARS MUCH OF THE CLOUD COVER ASSOCIATED WITH THE SHORTWAVE WILL STAY TO THE NORTHWEST. SO THIS LEAVES THE CURRENT CLOUD COVER AND SYSTEM GOING THROUGH THE MAIN CONCERN. WITH STRATUS EXTENDING SO FAR WEST...GRADUAL SUBSIDENCE OCCURRING TODAY IN THE WAKE OF THE SYSTEM AND THE LOW SUN ANGLE...THINKING A VERY PESSIMISTIC TREND MIGHT BE THE WAY TO GO. LIKE THE 04.00Z NAM INDICATING THE STRATUS STAYS IN PUT ACROSS THE AREA TODAY WITH ONLY SLOW CLEARING TONIGHT FOR WESTERN AREAS. CONCERNED THAT EVEN THE NAM MIGHT BE TOO FAST TONIGHT AS THE 900-950MB WINDS TURN FROM THE NORTHWEST TO NORTH. COMBINED WITH THE RECENT MOISTURE...CLOUDS MAY ACTUALLY LOWER IN CEILING HEIGHT VERSUS CLEARING. LAST CONCERN IS PRECIPITATION...BOTH THIS MORNING AND POSSIBLY OUT OF THE STRATUS DECK TONIGHT. GIVEN DIMINISHING RADAR RETURNS AND DRY FORECASTS INDICATED BY THE 04.00Z NAM/GFS/ECMWF FOR 12-18Z TODAY...HAVE REALLY DRIED OUT THIS MORNING. IN FACT...THERE MAY NOT BE MUCH GOING ON AFTER 12Z. WITH PRECIPITATION RAPIDLY DIMINISHING...WILL CANCEL THE ADVISORY HERE AT 4 AM. TONIGHT...THE 04.00Z NAM/GFS SHOW SOME LIGHT QPF OVER THE NORTH HALF OF WISCONSIN. APPEARS TO RESULT FROM LOW LEVEL CONVERGENCE...ASSOCIATED WITH SURFACE TROUGHING LINGERING BACK FROM THE CURRENT AREA OF LOW PRESSURE NEAR GRB. HAVE ADDED A 20 PERCENT CHANCE OF SNOW INTO THE FORECAST TO ACCOUNT FOR THIS POSSIBILITY. OTHERWISE...TEMPERATURES LOOK LIKE THEY SHOULD STRUGGLE TO RISE TODAY WITH 850MB TEMPS FALLING TO AT LEAST -6 TO -8C AND CLOUDS STAYING PUT. MAYBE A 1 OR 3 DEGREE F RISE IS POSSIBLE FROM THE 6 AM TEMPERATURE. WITH MORE CLOUDS ANTICIPATED TONIGHT...BROUGHT LOW TEMPERATURES UP A FEW DEGREES...ESPECIALLY ALONG AND EAST OF THE MISSISSIPPI RIVER WHERE CLOUDS ARE MORE CERTAIN. WHERE CLOUDS CLEAR OUT...TEMPERATURES COULD FALL INTO THE UPPER SINGLE DIGITS. MONDAY THROUGH TUESDAY NIGHT...BIG STORY/CONCERN HERE IS FORECASTING WHEN THE STRATUS WILL DISSIPATE AND ANY POTENTIAL PRECIPITATION OUT OF IT. UPPER TROUGH SITUATED OVER THE NORTHERN PLAINS IS FORECAST TO MARCH SOUTHEAST DURING THIS PERIOD...IN RESPONSE TO A POWERFUL UPPER TROUGH DIGGING FORMING OVER CENTRAL CANADA. NORTH TO NORTHEAST LOW LEVEL FLOW IS LIKELY MONDAY INTO MONDAY NIGHT WITH HIGH PRESSURE BUILDING INTO THE NORTHERN PLAINS. THIS FLOW SHOULD DO A DECENT JOB IN HOLDING IN THE STRATUS BELOW THE SUBSIDENCE INVERSION...UNTIL MAYBE LATE MONDAY NIGHT WHEN THERE IS SUGGESTION THE FLOW BACKS NORTHWEST TO BRING IN SOME DRIER LOW LEVEL AIR. IN ADDITION...THAT TROUGH MENTIONED IN THE TONIGHT DISCUSSION IS PROGGED TO DROP SOUTHWEST DUE TO THE LOW LEVEL FLOW. CONVERGENCE ALONG THIS TROUGH COULD RESULT IN SOME FLURRY ACTIVITY AND HAVE ADDED IT TO THE FORECAST. 04.00Z CANADIAN MODEL IS EVEN MORE AGGRESSIVE AND SHOWING A FEW HUNDREDTHS. IF OTHER MODELS...SUCH AS THE NAM/GFS START TO SHOW THIS IN LATER RUNS...MAY NEED TO HAVE SOME HIGHER CHANCES ADDED. BETTER POTENTIAL FOR CLEARING EXISTS TUESDAY AS THE SURFACE RIDGE MOVES IN AT THE SAME TIME WITH DAYTIME HEATING...SO INDICATED CLEARING STARTING HERE. UPPER RIDGING THEN BUILDS OVER THE AREA FOR TUESDAY NIGHT AHEAD OF THE POWERFUL UPPER TROUGH...MAINTAINING DRY CONDITIONS WITH GENERALLY MOSTLY CLEAR SKIES. FOR TEMPERATURES... LOOK FOR A COOLING TREND AS THE UPPER TROUGH MOVES IN. DID RAISE LOW TEMPERATURES UP MONDAY NIGHT IN THE CLOUDY SKY AREA...CLOSER TO THE 2 METER NAM12 GUIDANCE. OTHERWISE...A BLEND OF GUIDANCE SEEMED REASONABLE. .LONG TERM...WEDNESDAY THROUGH SATURDAY NIGHT 324 AM CST SUN DEC 4 2011 AFTER WHAT WAS SOME UNCERTAINTY IN THE LONG TERM FORECAST...CAUSED ESPECIALLY BY THE 03.12Z ECMWF SUGGESTING A POSSIBLE ADVISORY-TYPE SNOW MOVING THROUGH FRIDAY/FRIDAY NIGHT...ALL MODELS HAVE COME BACK INTO GREAT AGREEMENT ON THE UPPER AND SURFACE PATTERNS THROUGHOUT THE LONG TERM. IN FACT...THEY LOOK A LOT LIKE WHAT WAS SHOWN BY THE 03.00Z CYCLE. SO FOR NOW WILL CONSIDER THE 03.12Z ECMWF AN ODD OUTLIER. A WEST-NORTHWEST FLOW UPPER PATTERN BEGINS THE LONG TERM...ON THE SOUTH SIDE OF THE POWERFUL TROUGH DROPPING INTO SOUTHERN CANADA. A COLD FRONT LOOKS TO SLIDE THROUGH THE FORECAST AREA ON WEDNESDAY...ENDING A BRIEF WARM SURGE ALOFT CAUSED BY THE UPPER RIDGE. THEN FOR WEDNESDAY NIGHT AND THURSDAY...A SHORTWAVE TROUGH IS FORECAST TO DIG DOWN THE WEST SIDE OF THE CANADA UPPER TROUGH...CAUSING AN UPPER JET TO STRENGTHEN DOWNSTREAM OVER NORTHERN WISCONSIN. RIGHT ENTRANCE REGION FORCING OF THIS JET SHOULD INDUCE SOME MID-LEVEL FRONTOGENESIS...AND COMBINED WITH A LITTLE MOISTURE MAY PRODUCE A BAND OF LIGHT SNOW OVER FAR SOUTHERN SECTION THURSDAY NIGHT. INCLUDED A 20 PERCENT CHANCE FOR THIS. BIGGER IMPACT IS ON FRIDAY WHEN THE SHORTWAVE TROUGH MOVES ACROSS...CAUSING 850MB TEMPS TO TANK FROM -9 TO -13C ON THURSDAY TO AROUND -20C ON FRIDAY. NEEDLESS TO SAY...BELOW NORMAL TEMPERATURES LIKELY. A DRY AND SLOW WARMING TREND SHOULD THEN ENSUE HEADING INTO THE WEEKEND IN RESPONSE TO THE MODELS FORECASTING THE UPPER FLOW BECOMING MORE ZONAL. IN FACT...THE LATEST 04.00Z ECMWF SUGGESTS HIGHS APPROACHING 40 FOR NEXT SUNDAY AS A SURGE OF DOWNSLOPED WARMED PACIFIC AIR FLOWS INTO THE AREA. && .AVIATION...THROUGH 18Z MONDAY 1141 AM CST SUN DEC 4 2011 LOW LEVEL MOISTURE IN PLACE ACROSS THE REGION WILL CONTINUE TO PRODUCE MAINLY MVFR CEILINGS AT THE TAF SITES THROUGH LATE TONIGHT...WITH CEILINGS IN THE 1000 TO 1500 FT RANGE. AN UPPER LEVEL SHORTWAVE MOVING ACROSS THE AREA MAY PRODUCE SOME FLURRIES ACROSS THE TAF SITES AS IT MOVES THROUGH DURING THE EVENING AND OVERNIGHT HOURS. FORECAST SOUNDINGS SHOW A SMALL POSSIBILITY OF LOSING ICE ALOFT...WHICH COULD LEAD TO LIGHT FREEZING DRIZZLE. CONFIDENCE LOW ON THIS OCCURRING SO HAVE NOT INCLUDED IT IN THE TAFS AT THIS TIME. PLAN ON MVFR CONDITIONS AT KLSE THROUGH THE FORECAST PERIOD. THE STRATUS IS EXPECTED TO BECOME BKN TO SCT AT KRST AROUND 08Z TONIGHT...WHICH MAY PROVIDE A PERIOD OF VFR CONDITIONS LATE TONIGHT INTO EARLY MONDAY MORNING. LOOK FOR NORTHWEST WINDS AT 6 TO 10 KTS THROUGH THE FORECAST PERIOD. && .ARX WATCHES/WARNINGS/ADVISORIES... 324 AM CST SUN DEC 4 2011 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM....AJ AVIATION.....WETENKAMP