AREA FORECAST DISCUSSION
NWS DENVER CO
315 PM MST TUE DEC 27 2011 SHORT TERM...A MODERATE NORTHWESTERLY FLOW ALOFT REMAINS IN PLACE ACROSS THE CWFA TONIGHT. LATEST SATELLITE LOOPS INDICATE WEAK SHORTWAVE OVER WYOMING WITH THE TAIL END EXTENDING INTO NORTHWEST COLORADO. AT THIS TIME RADAR`S NOT SHOWING MUCH IN THE WAY OF PRECIP AND SURFACE OBS NOT REPORTING ANY SNOWFALL. LATEST RUC AND NAM QG VERTICAL VELOCITY PROGS SHOW SOME WEAK ASCENT IN THE MID LEVELS ACROSS THE NORTHERN TIER OF COLORADO AS IT MOVES ACROSS THE AREA THROUGH THE EARLY EVENING. MODEL CROSS SECTIONS THROUGH THE EVENING SHOW SOME INCREASE IN MOISTURE ALONG WITH FAIRLY DECENT OROGRAPHICS. STILL THINK THE COMBINATION OF ASCENT AND OROGRAPHICS WILL BE ENOUGH TO GENERATE SOME LIGHT SNOW...THOUGH NO QPF/SNOW INDICATED VIA THE MODELS. CROSS SECTIONS ALSO INDICATE AN INCREASE IN WINDS THROUGH 03Z WITH A PEAK OF CROSS MOUNTAIN FLOW OF 50 KTS AROUND 00Z. THE GUSTY WINDS SHOULD CREATE SOME BLOWING SNOW ACROSS THE MOUNTAINS AS WELL AS IN AND NEAR THE FOOTHILLS...MAINLY OVER THE HIGHER PASSES WHERE THERE IS DECENT SNOW COVER. WILL KEEP THE MENTION OF BLOWING SNOW IN THE GRIDS THROUGH 03Z. THE BLOWING SNOW LOOKS TO BE LESS OF AN ISSUE AND RATHER LOCALIZED FOR ZONE 39...BUT ENOUGH OF A THREAT TO KEEP IN THE GRIDS. BASED ON MODEL CROSS SECTIONS...SHOULD SEE A DECREASE IN WINDS AFTER 03Z AS CROSS MOUNTAIN FLOW DECREASES TO AROUND 35 KTS AT MOUNTAIN TOP. DROPPED THE SLIGHT CHANCE OF MOUNTAIN SNOW AFTER MIDNIGHT DUE TO THE LACK OF MOISTURE AND QG ASCENT. AS FOR THE PLAINS DRY CONDITIONS TO PREVAIL TONIGHT WITH DECREASING WINDS NEAR THE FOOTHILLS. ON WEDNESDAY...A MODERATE WEST TO NORTHWEST FLOW ALOFT PREVAILS OVER THE CFWA. MODELS SHOW ANOTHER WEAK SHORTWAVE SLIDING INTO IDAHO AND WESTERN WYOMING BY THE AFTERNOON. SOME INCREASE IN MID LEVEL MOISTURE NOTED ON CROSS SECTIONS OVER THE MOUNTAINS AFTER 18Z ALONG WITH SOME FAVORABLE OROGRAPHICS...BUT LAPSE RATES LOOK LOW AND QG VERTICAL PROGS INDICATING MINIMAL ASCENT. ANY SNOW CHANCES FOR THE MOUNTAINS LOOK LOW...WILL KEEP THE SLIGHT CHANCE FOR ZONES 31 AND 33 DURING THE AFTERNOON. AS FOR PLAINS...DRY CONDITIONS TO PREVAIL WITH SOME INCREASE IN HIGH LEVEL MOISTURE. NAM SHOWS SOME SURFACE WINDS TO AROUND 25 KTS NEAR THE WYOMING BORDER DURING THE AFTERNOON...OTHERWISE WINDS SHOULD BE FAIRLY LIGHT. TEMPERATURE AND THICKNESS PROGS SUGGEST HIGHS AROUND 50 ACROSS THE PLAINS...WITH LOWER 50S NEAR THE EASTERN BORDER ZONES. GUIDANCE TEMPERATURES SEEM A BIT TOO WARM WILL UNDERCUT A BIT WHERE THERE REMAINS SNOW COVER. .LONG TERM...A CHANCE OF SNOW WILL CONTINUE OVER MAINLY THE NORTHERN MOUNTAINS WEDNESDAY NIGHT THEN SPREAD SOUTH OF INTERSTATE 70 DURING THE DAY THURSDAY AS THE SHORTWAVE MOVES IN. AMOUNTS LOOK TO BE THE GREATEST OVER THE MOUNTAINS NEAR STEAMBOAT WITH BETWEEN 4 TO 6 INCHES FALLING BETWEEN WEDNESDAY AFTERNOON THROUGH THURSDAY NIGHT. AMOUNTS WILL BE LESS ELSEWHERE. ALSO WITH THE SHORTWAVE...WINDS OVER THE EASTERN MOUNTAINS AND ALONG THE FOOTHILLS WILL BE INCREASING. A DEEPENING SURFACE TROUGH OVER THE EASTERN PLAINS COMBINED WITH DOWNWARD QG MOTION AND A 130 KT JET NEARBY WILL BRING DOWNSLOPING GUSTS UP TO 65 MPH POSSIBLE OVER THE HIGHER TERRAIN EAST OF THE DIVIDE...ESPECIALLY OVER LARIMER AND BOULDER COUNTIES. WILL HOLD OFF ON ISSUING ANY HIGHLIGHTS...HOWEVER THE LATEST NAM MODEL THAT JUST CAME IN IS PLACING THE JET CLOSER OVERHEAD WHICH WOULD ALLOW STRONGER WINDS. WILL SEE IF OTHER MODELS FOLLOW SUIT. TEMPERATURES ON THURSDAY WILL WARMER DUE TO THE DOWNSLOPING WARMING...SHOULD SEE 50S OVER THE PLAINS WITH READINGS NEAR 60 OVER THE FAR NORTHEASTERN PLAINS. THE MINIMUM TEMPERATURES THAT NIGHT WILL ALSO REMAIN WARM. AN UPPER RIDGE WILL MOVE OVERHEAD ON FRIDAY TO KEEP IN THE WARM TEMPERATURES AND DRY CONDITIONS. CLOSE ON ITS HEELS HOWEVER WILL BE ANOTHER SHORTWAVE IN THE CONSTANT NORTHWEST FLOW ALOFT. THIS WILL BRING ANOTHER ROUND OF SNOW TO THE NORTHERN MOUNTAINS AND WINDY CONDITIONS SPREADING INTO THE FOOTHILLS...BUT WITH LIGHTER SPEEDS THAN THURSDAY. THE CHANCE OF SNOW WILL LAST INTO SATURDAY BEFORE A BIGGER UPPER RIDGE IS PROGGED TO MOVE OVER THE WESTERN STATES TO BRING WARM AND DRY WEATHER TO NORTHEASTERN COLORADO THROUGH THE WEEKEND AND INTO THE FIRST HALF OF NEXT WEEK...AND THE NEW YEAR. && AVIATION...VFR CONDITIONS TO CONTINUE THROUGH WEDNESDAY WITH VARYING AMOUNTS OF MAINLY HIGH LEVEL CLOUDS. SURFACE WINDS SHOULD WEAKEN DURING THE EVENING AND BECOME SOUTHWEST BY 03Z AS DRAINAGE PATTERN DEVELOPS. EXCEPTION WILL BE AT KBJC WHERE WESTERLY WINDS WILL PREVAIL OVERNIGHT WITH SOME GUSTS TO 30 KTS THROUGH 06Z. ON WEDNESDAY...SOUTHWEST SURFACE GRADIENT TO PREVAIL...WITH SPEEDS AROUND 12KTS. SOME GUSTS TO 20 KTS POSSIBLE AT KBJC...MAINLY IN THE MORNING. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....KRIEDERMAN AVIATION...D-L
AREA FORECAST DISCUSSION
NWS ALBANY NY
114 PM EST TUE DEC 27 2011 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL TRACK NORTHEAST ACROSS OUR REGION THIS AFTERNOON AND TONIGHT WITH WIDESPREAD PRECIPITATION AND BREEZY CONDITIONS. MAINLY RAIN IS EXPECTED FROM THIS SYSTEM...BUT AREAS WELL NORTH AND WEST OF ALBANY WILL GET SOME LIGHT SNOW ACCUMULATIONS...ESPECIALLY TONIGHT...AS RAIN CHANGES TO SNOW. VERY WINDY AND COLDER CONDITIONS WITH SCATTERED TO NUMEROUS SNOW AND OR RAIN SHOWERS WILL OCCUR WEDNESDAY...AS THE STORM MOVES INTO EASTERN CANADA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CLOUDS HAVE PRETTY MUCH SPREAD OVER THE ENTIRE AREA...AND AREA RADARS SHOWING SOME VIRGA. NO PRECIPITATION IS REACHING THE GROUND OVER THE REGION YET...BUT SHOULD DEVELOP OVERHEAD THROUGH THE AFTERNOON. TEMPERATURES HAVE WARMED RAPIDLY...BUT WITH THE CLOUD COVER AND EVENTUAL RAIN...TEMPERATURES SHOULD RISE ONLY A DEGREE OR TWO MORE THROUGH THIS AFTERNOON. CURRENT OBSERVATIONS AND TRENDS SUPPORT MOST OF THE CURRENT FORECAST THROUGH THIS AFTERNOON...SO FEW CHANGES NEEDED IF ANY. REV AFD BELOW... AS OF 950 AM EDT...LOW PRESSURE CONTINUES TO RAPIDLY FORM NEAR THE SRN APPALACHIANS THIS HOUR. THE BEST MSAS PRESSURE FALLS ARE NEAR W-CNTRL NC. THE WATER VAPOR LOOP HAS A SHORT-WAVE ROTATING AROUND A STRONG SOUTHERN STREAM NEGATIVELY TILTED UPPER TROUGH. A NORTHERN STREAM DISTURBANCE IS ALSO TRYING TO PHASE IN. A DUAL UPPER LEVEL JET STREAK STRUCTURE IS IN PLACE WITH THE STORM DEEPENING AND INTENSIFYING ALONG THE LEFT FROM QUADRANT OF A H250 JET STREAK OF 100+ KTS...AND A 140+ KT JET STREAM IS MOVING ACROSS SRN QUEBEC. THE LOW LEVEL JET WILL INCREASE AHEAD OF THE WAVE. THE H850 WINDS INCREASE TO 45-60 KTS BTWN 18Z-00Z. WE INCREASED THE S/SE WINDS TO 10 TO 20 MPH WITH SOME GUSTS IN THE 30-40 MPH LATE THIS PM AND EARLY THIS EVENING. THE STRONGEST WINDS LOOK LIKE THESE WILL BE ALONG THE SRN GREENS...ERN CATSKILLS...AND PORTIONS OF THE MOHAWK VALLEY INTO THE SRN DACKS. WE SLIGHTLY RETOOLED THE POPS BASED ON THE LATEST HRRR AND NAM12 WITH AN ONSET IN THE 21Z- 00Z TIME FRAME. THIS WAVE IS A FAST MOVER. THE DRY SLOT MAY REACH THE FCST AREA AS EARLY AS 03Z ! THE NAM SHOWS SOME ELEVATED INSTABILITY GRAZING THE SOUTHEAST EXTREME OF THE FCST AREA WITH SHOWALTER VALUES OF 0 TO -1C. THERE MAYBE A RUMBLE OF THUNDER SOUTH AND EAST OF THE CAPITAL REGION EARLY THIS EVENING. WE DID NOT ADD THUNDER TO THE GRIDS YET DUE TO LOW CONFIDENCE AND A SMALL PROBABILITY. FINALLY...A LOOK AT THE CRITICAL THICKNESSES AND MODEL SOUNDINGS INDICATE MAINLY A RAIN PTYPE WITH SOME SNOW TRANSITIONING TO RAIN...THEN BACK TO SNOW OVER THE SRN AND WRN ADIRONDACKS. THERE IS A VERY SMALL CHC OF A BRIEF PERIOD OF SOME POCKETS OF -FZRA IN THE SRN DACKS...BUT WE WERE NOT CONFIDENT TO ADD THIS PTYPE AT THIS TIME. TOTAL SNOWFALL AMOUNTS IN THE SRN DACKS WILL BE IN THE 2 TO 5 INCH RANGE. T/TD/RH/APPARENT TEMPS WERE REDONE BASED ON OBSERVATIONS...AND CLOUDS WERE RETOOLED BASED ON THE VIS/IR PICTURE...AS MID AND HIGH CLOUDS CONTINUES TO THICKEN AND LOWER. PREVIOUS NEAR TERM... AS OF 600 AM...HAVE MADE SOME ADJUSTMENTS TO THE HOURLY TEMP GRIDS...WITH LITTLE ELSE CHANGED. 06Z NAM/GFS ARE NOW IN...AND THEY CONTINUE TO SHOW A STORM TRACK THAT IS OVER THE NORTHWEST PART OF THE FORECAST AREA...SO WARM MOSTLY RAIN SOLUTION USED EARLIER TO PRODUCE THE FORECAST STILL LOOKS GOOD. ****PREVIOUS DISCUSSION**** HAVE WORKED THE PAST FEW NIGHTS AND HAVE SEEN THE MODELS CONTINUE THEIR TREND OF TRACKING THE UPCOMING STORM FURTHER AND FURTHER TO THE WEST. THE CURRENT 00Z RUNS ARE ALL NOW FORECASTING THE LOW TO PASS TO THE NORTH AND WEST OF ALBANY. WITH NO RETREATING FRIGID ARCTIC AIR MASS IN PLACE OVER THE REGION...THE WARMING THAT WILL RESULT FROM SUCH A TRACK WILL PRODUCE MOSTLY RAIN ACROSS THE FORECAST AREA...EVEN THE ADIRONDACK PART OF THE FORECAST AREA. RAIN WILL BEGIN TO SPREAD INTO THE FORECAST AREA FROM THE SOUTHWEST BY AROUND 200 PM...AND SPREAD SO RAPIDLY NORTHEAST THAT BY 5 OR 6 PM WIDESPREAD RAINFALL WILL BE FALLING ACROSS THE ENTIRE FORECAST AREA. A MIX OF SNOW AND RAIN IS POSSIBLE OVER THE FAR NORTHWEST PART OF THE FORECAST AREA...WHICH MAY CONTINUE THROUGH THE EVENING AS A MIX...THEN CHANGE TO ALL SNOW THERE AROUND OF AFTER 06Z TONIGHT. BY THE TIME THE CHANGEOVER TO ALL SNOW BEGINS...THE BULK OF THE PCPN WILL HAVE ALREADY PASSED...SO AM EXPECTING NO MORE THAN 1 TO 4 INCHES OF SNOW ACROSS HERKIMER... HAMILTON...NORTHERN FULTON AND NORTHERN WARREN COUNTIES. ELSEWHERE...RAIN MAY CHANGE TO SNOW BEFORE PCPN ENDS AS WELL...BUT IT WILL OCCUR SO LATE THAT LITTLE IF ANY ACCUMULATION IS EXPECTED. AN INCH OR LESS HAS BEEN FORECAST IN THE CENTRAL MOHAWK VALLEY...THE SCHOHARIE VALLEY AND EASTERN CATSKILLS LATE TONIGHT...WITH LITTLE OR NO SNOW ELSEWHERE. NO WINTER WEATHER ADVISORIES HAVE BEEN ISSUED AT THIS TIME SINCE SNOWFALL AMOUNTS ARE LESS THAN THE ADVISORY CRITERIA. HOWEVER...SINCE WE HAVE BEEN HIGHLIGHTING THIS EVENT IN THE HWOALY PRODUCT FOR THE PAST FEW DAYS...CONTINUED TO MENTION THE SNOW ACCUMULATIONS IN THE LATEST HWOALY. MODEL WIND FORECASTS AT 925 MB AND 850 INDICATE SOUTHERLY WINDS AT THOSE LEVELS WILL INCREASE TO 40 TO 50 KTS LATE TODAY AND THIS EVENING. HOWEVER...MOS WIND FORECASTS AND MODEL SOUNDINGS INDICATE THAT THESE STRONG WINDS ARE NOT LIKELY TO TRANSLATE DOWN TO THE SURFACE DUE TO THE RAIN/PCPN INDUCED LOW LEVEL INVERSION THAT IS LIKELY TO DEVELOP AFTER THE PCPN BEGINS. DAY SHIFT WILL NEED TO MONITOR FOR THE POSSIBILITY THAT THE STRONG SOUTHERLY WINDS ALOFT MAY MIX DOWN TO THE SURFACE...ESPECIALLY IF ANY CONVECTIVE ELEMENTS BEGIN TO DEVELOP LATER TODAY AS THE PCPN APPROACHES. TEMPS TODAY WILL RISE INTO THE UPPER 30S AND 40S BY LATE IN THE DAY...AND GENERALLY REMAIN AT THOSE LEVELS UNTIL THE SURFACE LOW MOVES BY AND WESTERLY WINDS BRING COLDER AIR IN. THIS IS NOT LIKELY TO HAPPEN UNTIL AROUND OR AFTER 06Z TONIGHT. BY SUNRISE WEDNESDAY MORNING...TEMPS WILL EVENTUALLY DROP INTO THE 20S OVER THE NORTHWEST...AND 30S ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... TYPICAL BLUSTERY CONDITIONS WITH SCATTERED TO NUMEROUS SNOW SHOWERS ACROSS THE REGION ON WEDNESDAY IN THE WAKE OF THE STORM...ESPECIALLY OVER HIGHER TERRAIN AND DOWNWIND OF LAKE ONTARIO. ANOTHER INCH OR TWO OF SNOW IS POSSIBLE FROM THE ADIRONDACKS TO THE MOHAWK AND SCHOHARIE VALLEYS AND EASTERN CATSKILLS ON WEDNESDAY...WITH LESSER AMOUNTS ELSEWHERE. MODELS CONTINUE TO SHOW 925 AND 850 WINDS IN THE 40 TO 50 KT RANGE ON WEDNESDAY...BUT WITH THE MIXING OF THE NOW WEST TO NORTHWEST WINDS DOWN TO THE SURFACE MUCH MORE LIKELY...THERE IS A BETTER CHANCE THAT A WIND ADVISORY MAY BE NEEDED ON WEDNESDAY...AND IT HAS BEEN HIGHLIGHTED IN THE HWOALY PRODUCT ACROSS THE ENTIRE FORECAST AREA. HAVE CURRENTLY FORECAST WINDS OF 15 TO 30 MPH WITH GUSTS OF 35 TO 45 MPH. TEMPS WEDNESDAY MAY ACTUALLY FALL OR REMAIN STEADY AS COLDER AIR SURGES IN. HAVE INDICATED HIGHS ON WEDNESDAY ONLY ABOUT A DEGREE OR TWO HIGHER THAN THE LOWS WEDNESDAY MORNING. WINDS AND SNOW SHOWERS WILL DIMINISH WEDNESDAY EVENING. EXPECT LEFTOVER SNOW SHOWERS TO COMPLETELY END DURING THE EVENING...BUT A DECENT WIND WILL CONTINUE THROUGH THE NIGHT WITH WIND GUSTS OF 25 TO 30 MPH POSSIBLE THROUGH WELL AFTER MIDNIGHT. LOWS WEDNESDAY NIGHT WILL RANGE FROM A FEW DEGREES BELOW ZERO OVER THE ADIRONDACKS...TO THE UPPER TEENS OVER THE SOUTH. A CLIPPER LIKE SYSTEM WILL MOVE THROUGH THE GREAT LAKES ON THURSDAY...BUT IT IS NOT LIKELY TO ARRIVE IN OUR AREA UNTIL THURSDAY NIGHT. SO HAVE KEPT THE FORECAST FOR THURSDAY DRY...BUT DID INCREASE THE CLOUD COVER. HIGHS THURSDAY WILL BE IN THE 20S TO MID 30S. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... A CLIPPER TYPE LOW APPROACHES THE REGION THURSDAY NIGHT RESULTING IN CLOUDY SKIES...LOW CHANCE POPS...AND LOW TEMPS FROM AROUND 10 ABOVE NORTH TO THE UPPER 20S SOUTH. PRECIP AMOUNTS...ALL SNOW... WILL BE VERY LIGHT AS THE THE SYSTEM IS MOISTURE STARVED. THE CLIPPER MOVES ACROSS THE REGION ON FRIDAY. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF WHICH SLOWS DOWN THE MOVEMENT OF THE CLIPPER AND MOVES IT FARTHER SOUTH. WARMER AIR IS DRAWN IN AHEAD OF THE CLIPPER WHICH CHANGES THE PRECIP FROM SNOW TO RAIN OVER MUCH OF THE REGION AND INCREASES THE PRECIP AMOUNTS TO THE SOUTH OF THE RAIN SNOW LINE. HIGHS FRIDAY WILL RANGE FROM AROUND 30 NORTH TO THE LOW 40S SOUTH. THE PASSAGE OF THE CLIPPER WILL BE FOLLOWED BY A SURGE OF COLD AIR WITH 850 TEMPS AROUND MINUS 10 WITH LOWS FRIDAY NIGHT FROM THE HIGH SINGLES NORTH TO THE MID 20S SOUTH. WESTERLY WINDS WILL RESULT IN A CHANCE FOR SOME LAKE ENHANCED PRECIP WITH THE COLD ADVECTION WEST...ENOUGH FOR CHANCE POPS DOWN THE MOHAWK VALLEY AND ELEVATED TERRAIN WEST OF THE HUDSON VALLEY...WITH ONLY SLIGHT CHANCE POPS FARTHER EAST. HIGHS SATURDAY WILL RANGE FROM THE MID 20S TO AROUND 40. HIGH PRESSURE BRIEFLY CROSSES THE REGION SATURDAY INTO SATURDAY NIGHT AND WINDS BACK AROUND TO A SOUTHWESTERLY DIRECTION BRINGING WARMER AIR INTO THE REGION. LOWS SATURDAY NIGHT WILL RANGE FROM AROUND 20 NORTH TO 30 SOUTH. THE NEXT IN A SERIES OF CLIPPERS MOVES ACROSS CANADA NORTH OF THE REGION ON SUNDAY...BRINGING A MIXED BAG OF RAIN AND SNOW SHOWERS DEPENDING ON THE LATITUDE... ELEVATION...AND TIME OF DAY. HIGHS SUNDAY WILL RANGE FROM THE MID 30S NORTH TO THE LOWER 40S SOUTH. AS THE LOW MOVES EAST IT BRINGS ANOTHER BLAST OF COLD IN ITS WAKE...CHANGING THE RAIN TO SNOW SUNDAY EVENING. LOWS SUNDAY NIGHT WILL RANGE FROM THE LOWER TEENS TO THE MID 20S. MONDAY LOOKS TO BE BLUSTERY AND COLD WITH BRISK NORTHWEST WINDS 15 TO 25 MPH DURING THE MIDDAY PERIOD AND HIGHS ONLY FROM AROUND 20 NORTH TO THE UPPER 30S SOUTH. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... LOW PRESSURE CONTINUES TO DEEPEN AND INTENSIFY NEAR THE PIEDMONT REGION THIS AFTERNOON. THE CYCLONE WILL QUICKLY MOVE NORTHEAST ACROSS CENTRAL NY THIS EVENING...AND INTO SOUTHEAST QUEBEC AFTER MIDNIGHT. VFR FLIGHT CONDITIONS WILL PERSIST PRIOR TO SUNSET...THEN CONDITIONS WILL DETERIORATE BETWEEN 21Z TO 00Z WITH THE THERMAL ADVECTION RAINFALL AHEAD OF THE INTENSIFYING CYCLONE. CONDITIONS WILL LOWER TO MVFR VIS/CIG LEVELS...AND POTENTIALLY IFR LEVELS AT KPOU PRIOR TO 00Z. THERE IS A MODERATE PROBABILITY THAT CONDITIONS MAY DECREASE TO IFR LEVELS AT KALB AND KGFL BTWN 00Z-06Z/WED IN THE PCPN SHIELD AHEAD OF THE WAVE. WE KEPT KALB AT LOW MVFR LEVELS...AND LOWERED KGFL ALONG WITH KPOU TO IFR CONDITIONS IN THAT TIME FRAME. THE DRY SLOT TO THE SYSTEM MOVES INTO CNTRL-ERN NY AROUND MIDNIGHT. THE PCPN WILL END AND CONDITIONS WILL RISE TO MVFR LEVELS AT ALL THE SITES. CIGS WILL HANG AT HIGH MVFR AT KALB NORTH TO KGFL LATE AND THE MORNING...WITH KPOU RISING TO LOW VFR CIGS LEVELS AFTER SUNRISE. LOW LEVEL WIND SHEAR WILL BE AT LEAST A FACTOR AT KPOU BTWN 21Z- 04Z WITH THE 2 KFT AGL WINDS INCREASING TO 40-50 KTS. WE ADDED LLWS GROUPS THERE. THE SFC WINDS WILL GENERALLY BE 10 KTS OR LESS. FOR KALB AND KGFL...THE WINDS WILL BE FROM S/SE AT 8-15 KTS. THE 2 KFT AGL WINDS ARE EXPECTED TO BE AROUND 30-35 KTS. OVERALL THE WINDS WILL BACK FROM THE S/SE TO THE E/NE AT 5-10 KTS. EARLY THIS EVENING. THEY WILL VEER TO THE SW AFTER MIDNIGHT AT AROUND 10 KTS. THE WINDS WILL INCREASE FROM THE WEST AFTER 12Z AT 12-18 KTS WITH SOME GUSTS GREATER THAN 25 KTS /ESPECIALLY AT KALB DUE TO FUNNELING DOWN THE MOHAWK RIVER VALLEY/ WITH THE LOW LEVEL PRESSURE GRADIENT INCREASING BETWEEN THE DEPARTING STORM AND HIGH PRESSURE BUILDING IN FROM THE LOWER MS RIVER VALLEY. ALSO...THE BUFKIT MOMENTUM TRANSFER PROFILES INDICATED GUSTS GREATER THAN 30 KTS MAY BE NEEDED IN THE AFTERNOON. OUTLOOK... WED PM...MVFR IMPROVING TO VFR. WINDY THU...VFR. NO SIG WX. FRI...VFR/MVFR...CHC -SHSN/-SHRA. SAT- SUN...VFR...SLIGHT CHC -SHSN/-SHRA. && .HYDROLOGY... WHILE A SOAKING RAIN OF UP TO AROUND AN INCH IS EXPECTED THROUGH TONIGHT...IT IS NOT EXPECTED TO RESULT IN FLOODING. RAIN IS EXPECTED TO START LATE THIS AFTERNOON AND CONTINUE THROUGH TONIGHT. THE RAIN WILL MIX WITH AND CHANGE TO SNOW WELL NORTH AND WEST OF THE ALBANY AREA. HEAVIEST RAINFALL AMOUNTS ARE EXPECTED IN THE MID HUDSON REGION OF NEW YORK AND OVER THE HOUSATONIC VALLEY AND LITCHFIELD HILLS OF CONNECTICUT. MODEST RISES MAY BE EXPECTED ON THE RIVERS AND STREAMS IN THIS AREA...BUT THE RAIN IS NOT EXPECTED TO BE HEAVY ENOUGH TO BRING RIVERS UP TO FLOOD. DRY WEATHER ON THURSDAY WILL ALLOW RIVERS AND STREAMS TO RECEDE. A SERIES OF CLIPPER TYPE LOWS OVER THE NEW YEARS WEEKEND WILL HAVE LITTLE EFFECT ON THE RIVERS SINCE MOISTURE WILL BE LACKING WITH THEM. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...NAS NEAR TERM...NAS SHORT TERM...GJM LONG TERM...RCK AVIATION...WASULA HYDROLOGY...RCK
AREA FORECAST DISCUSSION
NWS ALBANY NY
1223 PM EST TUE DEC 27 2011 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL TRACK NORTHEAST ACROSS OUR REGION THIS AFTERNOON AND TONIGHT WITH WIDESPREAD PRECIPITATION AND BREEZY CONDITIONS. MAINLY RAIN IS EXPECTED FROM THIS SYSTEM...BUT AREAS WELL NORTH AND WEST OF ALBANY WILL GET SOME LIGHT SNOW ACCUMULATIONS...ESPECIALLY TONIGHT...AS RAIN CHANGES TO SNOW. VERY WINDY AND COLDER CONDITIONS WITH SCATTERED TO NUMEROUS SNOW AND OR RAIN SHOWERS WILL OCCUR WEDNESDAY...AS THE STORM MOVES INTO EASTERN CANADA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CLOUDS HAVE PRETTY MUCH SPREAD OVER THE ENTIRE AREA...AND AREA RADARS SHOWING SOME VIRGA. NO PRECIPITATION IS REACHING THE GROUND OVER THE REGION YET...BUT SHOULD DEVELOP OVERHEAD THROUGH THE AFTERNOON. TEMPERATURES HAVE WARMED RAPIDLY...BUT WITH THE CLOUD COVER AND EVENTUAL RAIN...TEMPERATURES SHOULD RISE ONLY A DEGREE OR TWO MORE THROUGH THIS AFTERNOON. CURRENT OBSERVATIONS AND TRENDS SUPPORT MOST OF THE CURRENT FORECAST THROUGH THIS AFTERNOON...SO FEW CHANGES NEEDED IF ANY. REV AFD BELOW... AS OF 950 AM EDT...LOW PRESSURE CONTINUES TO RAPIDLY FORM NEAR THE SRN APPALACHIANS THIS HOUR. THE BEST MSAS PRESSURE FALLS ARE NEAR W-CNTRL NC. THE WATER VAPOR LOOP HAS A SHORT-WAVE ROTATING AROUND A STRONG SOUTHERN STREAM NEGATIVELY TILTED UPPER TROUGH. A NORTHERN STREAM DISTURBANCE IS ALSO TRYING TO PHASE IN. A DUAL UPPER LEVEL JET STREAK STRUCTURE IS IN PLACE WITH THE STORM DEEPENING AND INTENSIFYING ALONG THE LEFT FROM QUADRANT OF A H250 JET STREAK OF 100+ KTS...AND A 140+ KT JET STREAM IS MOVING ACROSS SRN QUEBEC. THE LOW LEVEL JET WILL INCREASE AHEAD OF THE WAVE. THE H850 WINDS INCREASE TO 45-60 KTS BTWN 18Z-00Z. WE INCREASED THE S/SE WINDS TO 10 TO 20 MPH WITH SOME GUSTS IN THE 30-40 MPH LATE THIS PM AND EARLY THIS EVENING. THE STRONGEST WINDS LOOK LIKE THESE WILL BE ALONG THE SRN GREENS...ERN CATSKILLS...AND PORTIONS OF THE MOHAWK VALLEY INTO THE SRN DACKS. WE SLIGHTLY RETOOLED THE POPS BASED ON THE LATEST HRRR AND NAM12 WITH AN ONSET IN THE 21Z- 00Z TIME FRAME. THIS WAVE IS A FAST MOVER. THE DRY SLOT MAY REACH THE FCST AREA AS EARLY AS 03Z ! THE NAM SHOWS SOME ELEVATED INSTABILITY GRAZING THE SOUTHEAST EXTREME OF THE FCST AREA WITH SHOWALTER VALUES OF 0 TO -1C. THERE MAYBE A RUMBLE OF THUNDER SOUTH AND EAST OF THE CAPITAL REGION EARLY THIS EVENING. WE DID NOT ADD THUNDER TO THE GRIDS YET DUE TO LOW CONFIDENCE AND A SMALL PROBABILITY. FINALLY...A LOOK AT THE CRITICAL THICKNESSES AND MODEL SOUNDINGS INDICATE MAINLY A RAIN PTYPE WITH SOME SNOW TRANSITIONING TO RAIN...THEN BACK TO SNOW OVER THE SRN AND WRN ADIRONDACKS. THERE IS A VERY SMALL CHC OF A BRIEF PERIOD OF SOME POCKETS OF -FZRA IN THE SRN DACKS...BUT WE WERE NOT CONFIDENT TO ADD THIS PTYPE AT THIS TIME. TOTAL SNOWFALL AMOUNTS IN THE SRN DACKS WILL BE IN THE 2 TO 5 INCH RANGE. T/TD/RH/APPARENT TEMPS WERE REDONE BASED ON OBSERVATIONS...AND CLOUDS WERE RETOOLED BASED ON THE VIS/IR PICTURE...AS MID AND HIGH CLOUDS CONTINUES TO THICKEN AND LOWER. PREVIOUS NEAR TERM... AS OF 600 AM...HAVE MADE SOME ADJUSTMENTS TO THE HOURLY TEMP GRIDS...WITH LITTLE ELSE CHANGED. 06Z NAM/GFS ARE NOW IN...AND THEY CONTINUE TO SHOW A STORM TRACK THAT IS OVER THE NORTHWEST PART OF THE FORECAST AREA...SO WARM MOSTLY RAIN SOLUTION USED EARLIER TO PRODUCE THE FORECAST STILL LOOKS GOOD. ****PREVIOUS DISCUSSION**** HAVE WORKED THE PAST FEW NIGHTS AND HAVE SEEN THE MODELS CONTINUE THEIR TREND OF TRACKING THE UPCOMING STORM FURTHER AND FURTHER TO THE WEST. THE CURRENT 00Z RUNS ARE ALL NOW FORECASTING THE LOW TO PASS TO THE NORTH AND WEST OF ALBANY. WITH NO RETREATING FRIGID ARCTIC AIR MASS IN PLACE OVER THE REGION...THE WARMING THAT WILL RESULT FROM SUCH A TRACK WILL PRODUCE MOSTLY RAIN ACROSS THE FORECAST AREA...EVEN THE ADIRONDACK PART OF THE FORECAST AREA. RAIN WILL BEGIN TO SPREAD INTO THE FORECAST AREA FROM THE SOUTHWEST BY AROUND 200 PM...AND SPREAD SO RAPIDLY NORTHEAST THAT BY 5 OR 6 PM WIDESPREAD RAINFALL WILL BE FALLING ACROSS THE ENTIRE FORECAST AREA. A MIX OF SNOW AND RAIN IS POSSIBLE OVER THE FAR NORTHWEST PART OF THE FORECAST AREA...WHICH MAY CONTINUE THROUGH THE EVENING AS A MIX...THEN CHANGE TO ALL SNOW THERE AROUND OF AFTER 06Z TONIGHT. BY THE TIME THE CHANGEOVER TO ALL SNOW BEGINS...THE BULK OF THE PCPN WILL HAVE ALREADY PASSED...SO AM EXPECTING NO MORE THAN 1 TO 4 INCHES OF SNOW ACROSS HERKIMER... HAMILTON...NORTHERN FULTON AND NORTHERN WARREN COUNTIES. ELSEWHERE...RAIN MAY CHANGE TO SNOW BEFORE PCPN ENDS AS WELL...BUT IT WILL OCCUR SO LATE THAT LITTLE IF ANY ACCUMULATION IS EXPECTED. AN INCH OR LESS HAS BEEN FORECAST IN THE CENTRAL MOHAWK VALLEY...THE SCHOHARIE VALLEY AND EASTERN CATSKILLS LATE TONIGHT...WITH LITTLE OR NO SNOW ELSEWHERE. NO WINTER WEATHER ADVISORIES HAVE BEEN ISSUED AT THIS TIME SINCE SNOWFALL AMOUNTS ARE LESS THAN THE ADVISORY CRITERIA. HOWEVER...SINCE WE HAVE BEEN HIGHLIGHTING THIS EVENT IN THE HWOALY PRODUCT FOR THE PAST FEW DAYS...CONTINUED TO MENTION THE SNOW ACCUMULATIONS IN THE LATEST HWOALY. MODEL WIND FORECASTS AT 925 MB AND 850 INDICATE SOUTHERLY WINDS AT THOSE LEVELS WILL INCREASE TO 40 TO 50 KTS LATE TODAY AND THIS EVENING. HOWEVER...MOS WIND FORECASTS AND MODEL SOUNDINGS INDICATE THAT THESE STRONG WINDS ARE NOT LIKELY TO TRANSLATE DOWN TO THE SURFACE DUE TO THE RAIN/PCPN INDUCED LOW LEVEL INVERSION THAT IS LIKELY TO DEVELOP AFTER THE PCPN BEGINS. DAY SHIFT WILL NEED TO MONITOR FOR THE POSSIBILITY THAT THE STRONG SOUTHERLY WINDS ALOFT MAY MIX DOWN TO THE SURFACE...ESPECIALLY IF ANY CONVECTIVE ELEMENTS BEGIN TO DEVELOP LATER TODAY AS THE PCPN APPROACHES. TEMPS TODAY WILL RISE INTO THE UPPER 30S AND 40S BY LATE IN THE DAY...AND GENERALLY REMAIN AT THOSE LEVELS UNTIL THE SURFACE LOW MOVES BY AND WESTERLY WINDS BRING COLDER AIR IN. THIS IS NOT LIKELY TO HAPPEN UNTIL AROUND OR AFTER 06Z TONIGHT. BY SUNRISE WEDNESDAY MORNING...TEMPS WILL EVENTUALLY DROP INTO THE 20S OVER THE NORTHWEST...AND 30S ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... TYPICAL BLUSTERY CONDITIONS WITH SCATTERED TO NUMEROUS SNOW SHOWERS ACROSS THE REGION ON WEDNESDAY IN THE WAKE OF THE STORM...ESPECIALLY OVER HIGHER TERRAIN AND DOWNWIND OF LAKE ONTARIO. ANOTHER INCH OR TWO OF SNOW IS POSSIBLE FROM THE ADIRONDACKS TO THE MOHAWK AND SCHOHARIE VALLEYS AND EASTERN CATSKILLS ON WEDNESDAY...WITH LESSER AMOUNTS ELSEWHERE. MODELS CONTINUE TO SHOW 925 AND 850 WINDS IN THE 40 TO 50 KT RANGE ON WEDNESDAY...BUT WITH THE MIXING OF THE NOW WEST TO NORTHWEST WINDS DOWN TO THE SURFACE MUCH MORE LIKELY...THERE IS A BETTER CHANCE THAT A WIND ADVISORY MAY BE NEEDED ON WEDNESDAY...AND IT HAS BEEN HIGHLIGHTED IN THE HWOALY PRODUCT ACROSS THE ENTIRE FORECAST AREA. HAVE CURRENTLY FORECAST WINDS OF 15 TO 30 MPH WITH GUSTS OF 35 TO 45 MPH. TEMPS WEDNESDAY MAY ACTUALLY FALL OR REMAIN STEADY AS COLDER AIR SURGES IN. HAVE INDICATED HIGHS ON WEDNESDAY ONLY ABOUT A DEGREE OR TWO HIGHER THAN THE LOWS WEDNESDAY MORNING. WINDS AND SNOW SHOWERS WILL DIMINISH WEDNESDAY EVENING. EXPECT LEFTOVER SNOW SHOWERS TO COMPLETELY END DURING THE EVENING...BUT A DECENT WIND WILL CONTINUE THROUGH THE NIGHT WITH WIND GUSTS OF 25 TO 30 MPH POSSIBLE THROUGH WELL AFTER MIDNIGHT. LOWS WEDNESDAY NIGHT WILL RANGE FROM A FEW DEGREES BELOW ZERO OVER THE ADIRONDACKS...TO THE UPPER TEENS OVER THE SOUTH. A CLIPPER LIKE SYSTEM WILL MOVE THROUGH THE GREAT LAKES ON THURSDAY...BUT IT IS NOT LIKELY TO ARRIVE IN OUR AREA UNTIL THURSDAY NIGHT. SO HAVE KEPT THE FORECAST FOR THURSDAY DRY...BUT DID INCREASE THE CLOUD COVER. HIGHS THURSDAY WILL BE IN THE 20S TO MID 30S. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... A CLIPPER TYPE LOW APPROACHES THE REGION THURSDAY NIGHT RESULTING IN CLOUDY SKIES...LOW CHANCE POPS...AND LOW TEMPS FROM AROUND 10 ABOVE NORTH TO THE UPPER 20S SOUTH. PRECIP AMOUNTS...ALL SNOW... WILL BE VERY LIGHT AS THE THE SYSTEM IS MOISTURE STARVED. THE CLIPPER MOVES ACROSS THE REGION ON FRIDAY. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF WHICH SLOWS DOWN THE MOVEMENT OF THE CLIPPER AND MOVES IT FARTHER SOUTH. WARMER AIR IS DRAWN IN AHEAD OF THE CLIPPER WHICH CHANGES THE PRECIP FROM SNOW TO RAIN OVER MUCH OF THE REGION AND INCREASES THE PRECIP AMOUNTS TO THE SOUTH OF THE RAIN SNOW LINE. HIGHS FRIDAY WILL RANGE FROM AROUND 30 NORTH TO THE LOW 40S SOUTH. THE PASSAGE OF THE CLIPPER WILL BE FOLLOWED BY A SURGE OF COLD AIR WITH 850 TEMPS AROUND MINUS 10 WITH LOWS FRIDAY NIGHT FROM THE HIGH SINGLES NORTH TO THE MID 20S SOUTH. WESTERLY WINDS WILL RESULT IN A CHANCE FOR SOME LAKE ENHANCED PRECIP WITH THE COLD ADVECTION WEST...ENOUGH FOR CHANCE POPS DOWN THE MOHAWK VALLEY AND ELEVATED TERRAIN WEST OF THE HUDSON VALLEY...WITH ONLY SLIGHT CHANCE POPS FARTHER EAST. HIGHS SATURDAY WILL RANGE FROM THE MID 20S TO AROUND 40. HIGH PRESSURE BRIEFLY CROSSES THE REGION SATURDAY INTO SATURDAY NIGHT AND WINDS BACK AROUND TO A SOUTHWESTERLY DIRECTION BRINGING WARMER AIR INTO THE REGION. LOWS SATURDAY NIGHT WILL RANGE FROM AROUND 20 NORTH TO 30 SOUTH. THE NEXT IN A SERIES OF CLIPPERS MOVES ACROSS CANADA NORTH OF THE REGION ON SUNDAY...BRINGING A MIXED BAG OF RAIN AND SNOW SHOWERS DEPENDING ON THE LATITUDE... ELEVATION...AND TIME OF DAY. HIGHS SUNDAY WILL RANGE FROM THE MID 30S NORTH TO THE LOWER 40S SOUTH. AS THE LOW MOVES EAST IT BRINGS ANOTHER BLAST OF COLD IN ITS WAKE...CHANGING THE RAIN TO SNOW SUNDAY EVENING. LOWS SUNDAY NIGHT WILL RANGE FROM THE LOWER TEENS TO THE MID 20S. MONDAY LOOKS TO BE BLUSTERY AND COLD WITH BRISK NORTHWEST WINDS 15 TO 25 MPH DURING THE MIDDAY PERIOD AND HIGHS ONLY FROM AROUND 20 NORTH TO THE UPPER 30S SOUTH. && .AVIATION /17Z TUESDAY THROUGH SATURDAY/... VFR FLIGHT CONDITIONS AND NO AVIATION WEATHER PROBLEMS ARE EXPECTED THROUGH MID TO LATE AFTERNOON. SCATTERED HIGH CLOUDS WILL THICKEN SOME AND LOWER DURING THE MORNING HOURS...WITH AN ALTOSTRATUS DECK AROUND 15000 FT ASL BY MID TO LATE MORNING. WINDS THIS MORNING WILL BE SOUTH 5 TO 10 KNOTS THIS MORNING AND MOST OF THE AFTERNOON. AS A LOW CENTER MOVES FROM THE OHIO VALLEY INTO THE MID ATLANTIC REGION THIS AFTERNOON...CONDITIONS WILL DETERIORATE LATER THIS AFTERNOON...WITH MVFR CONDITIONS AT BEST FOR THE EVENING HOURS AS RAIN OVERSPREADS THE REGION. THE CEILING AND VISIBLITY ARE LIKELY TO LOWER TO IFR DURING THE LATE EVENING HOURS AS THE BOUNDARY LAYER BECOMES MOISTER...WITH WINDS BECOMING SOUTHEAST DURING THE LATE AFTERNOON AND EARLY EVENING. WIDESPREAD IFR MAY BE EXPECTED DURING THE NIGHTTIME HOURS DUE TO LOW CEILINGS AND POOR VISIBILITY. SOME IMPROVEMENT TO MVFR MAY TAKE PLACE LATER TONIGHT AS THE STORM LIFTS NORTH INTO CANADA. LLWS MAY BECOME A FACTOR LATE THIS AFTERNOON AND EVENING AS WINDS 2000 TO 3000 FT AGL INCREASE TO 40-55 KTS. OUTLOOK... WED...MVFR...RAIN MIXING WITH SNOW AND TAPERING OFF TO SHWRS. WINDY. THU...VFR. NO SIG WX. FRI...VFR/MVFR...CHC -SHSN/-SHRA. && .HYDROLOGY... WHILE A SOAKING RAIN OF UP TO AROUND AN INCH IS EXPECTED THROUGH TONIGHT...IT IS NOT EXPECTED TO RESULT IN FLOODING. RAIN IS EXPECTED TO START LATE THIS AFTERNOON AND CONTINUE THROUGH TONIGHT. THE RAIN WILL MIX WITH AND CHANGE TO SNOW WELL NORTH AND WEST OF THE ALBANY AREA. HEAVIEST RAINFALL AMOUNTS ARE EXPECTED IN THE MID HUDSON REGION OF NEW YORK AND OVER THE HOUSATONIC VALLEY AND LITCHFIELD HILLS OF CONNECTICUT. MODEST RISES MAY BE EXPECTED ON THE RIVERS AND STREAMS IN THIS AREA...BUT THE RAIN IS NOT EXPECTED TO BE HEAVY ENOUGH TO BRING RIVERS UP TO FLOOD. DRY WEATHER ON THURSDAY WILL ALLOW RIVERS AND STREAMS TO RECEDE. A SERIES OF CLIPPER TYPE LOWS OVER THE NEW YEARS WEEKEND WILL HAVE LITTLE EFFECT ON THE RIVERS SINCE MOISTURE WILL BE LACKING WITH THEM. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...NAS NEAR TERM...NAS
AREA FORECAST DISCUSSION
NWS ALBANY NY
1014 AM EST TUE DEC 27 2011 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL TRACK NORTHEAST ACROSS OUR REGION LATE TODAY AND TONIGHT WITH WIDESPREAD PRECIPITATION AND BREEZY CONDITIONS. MAINLY RAIN IS EXPECTED FROM THIS SYSTEM...BUT AREAS WELL NORTH AND WEST OF ALBANY WILL GET SOME LIGHT SNOW ACCUMULATIONS...ESPECIALLY TONIGHT...AS RAIN CHANGES TO SNOW. VERY WINDY AND COLDER CONDITIONS WITH SCATTERED TO NUMEROUS SNOW AND OR RAIN SHOWERS WILL OCCUR WEDNESDAY...AS THE STORM MOVES INTO EASTERN CANADA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 950 AM EDT...LOW PRESSURE CONTINUES TO RAPIDLY FORM NEAR THE SRN APPALACHIANS THIS HOUR. THE BEST MSAS PRESSURE FALLS ARE NEAR W-CNTRL NC. THE WATER VAPOR LOOP HAS A SHORT-WAVE ROTATING AROUND A STRONG SOUTHERN STREAM NEGATIVELY TILTED UPPER TROUGH. A NORTHERN STREAM DISTURBANCE IS ALSO TRYING TO PHASE IN. A DUAL UPPER LEVEL JET STREAK STRUCTURE IS IN PLACE WITH THE STORM DEEPENING AND INTENSIFYING ALONG THE LEFT FROM QUADRANT OF A H250 JET STREAK OF 100+ KTS...AND A 140+ KT JET STREAM IS MOVING ACROSS SRN QUEBEC. THE LOW LEVEL JET WILL INCREASE AHEAD OF THE WAVE. THE H850 WINDS INCREASE TO 45-60 KTS BTWN 18Z-00Z. WE INCREASED THE S/SE WINDS TO 10 TO 20 MPH WITH SOME GUSTS IN THE 30-40 MPH LATE THIS PM AND EARLY THIS EVENING. THE STRONGEST WINDS LOOK LIKE THESE WILL BE ALONG THE SRN GREENS...ERN CATSKILLS...AND PORTIONS OF THE MOHAWK VALLEY INTO THE SRN DACKS. WE SLIGHTLY RETOOLED THE POPS BASED ON THE LATEST HRRR AND NAM12 WITH AN ONSET IN THE 21Z- 00Z TIME FRAME. THIS WAVE IS A FAST MOVER. THE DRY SLOT MAY REACH THE FCST AREA AS EARLY AS 03Z ! THE NAM SHOWS SOME ELEVATED INSTABILITY GRAZING THE SOUTHEAST EXTREME OF THE FCST AREA WITH SHOWALTER VALUES OF 0 TO -1C. THERE MAYBE A RUMBLE OF THUNDER SOUTH AND EAST OF THE CAPITAL REGION EARLY THIS EVENING. WE DID NOT ADD THUNDER TO THE GRIDS YET DUE TO LOW CONFIDENCE AND A SMALL PROBABILITY. FINALLY...A LOOK AT THE CRITICAL THICKNESSES AND MODEL SOUNDINGS INDICATE MAINLY A RAIN PTYPE WITH SOME SNOW TRANSITIONING TO RAIN...THEN BACK TO SNOW OVER THE SRN AND WRN ADIRONDACKS. THERE IS A VERY SMALL CHC OF A BRIEF PERIOD OF SOME POCKETS OF -FZRA IN THE SRN DACKS...BUT WE WERE NOT CONFIDENT TO ADD THIS PTYPE AT THIS TIME. TOTAL SNOWFALL AMOUNTS IN THE SRN DACKS WILL BE IN THE 2 TO 5 INCH RANGE. T/TD/RH/APPARENT TEMPS WERE REDONE BASED ON OBSERVATIONS...AND CLOUDS WERE RETOOLED BASED ON THE VIS/IR PICTURE...AS MID AND HIGH CLOUDS CONTINUES TO THICKEN AND LOWER. PREVIOUS NEAR TERM... AS OF 600 AM...HAVE MADE SOME ADJUSTMENTS TO THE HOURLY TEMP GRIDS...WITH LITTLE ELSE CHANGED. 06Z NAM/GFS ARE NOW IN...AND THEY CONTINUE TO SHOW A STORM TRACK THAT IS OVER THE NORTHWEST PART OF THE FORECAST AREA...SO WARM MOSTLY RAIN SOLUTION USED EARLIER TO PRODUCE THE FORECAST STILL LOOKS GOOD. ****PREVIOUS DISCUSSION**** HAVE WORKED THE PAST FEW NIGHTS AND HAVE SEEN THE MODELS CONTINUE THEIR TREND OF TRACKING THE UPCOMING STORM FURTHER AND FURTHER TO THE WEST. THE CURRENT 00Z RUNS ARE ALL NOW FORECASTING THE LOW TO PASS TO THE NORTH AND WEST OF ALBANY. WITH NO RETREATING FRIGID ARCTIC AIR MASS IN PLACE OVER THE REGION...THE WARMING THAT WILL RESULT FROM SUCH A TRACK WILL PRODUCE MOSTLY RAIN ACROSS THE FORECAST AREA...EVEN THE ADIRONDACK PART OF THE FORECAST AREA. RAIN WILL BEGIN TO SPREAD INTO THE FORECAST AREA FROM THE SOUTHWEST BY AROUND 200 PM...AND SPREAD SO RAPIDLY NORTHEAST THAT BY 5 OR 6 PM WIDESPREAD RAINFALL WILL BE FALLING ACROSS THE ENTIRE FORECAST AREA. A MIX OF SNOW AND RAIN IS POSSIBLE OVER THE FAR NORTHWEST PART OF THE FORECAST AREA...WHICH MAY CONTINUE THROUGH THE EVENING AS A MIX...THEN CHANGE TO ALL SNOW THERE AROUND OF AFTER 06Z TONIGHT. BY THE TIME THE CHANGEOVER TO ALL SNOW BEGINS...THE BULK OF THE PCPN WILL HAVE ALREADY PASSED...SO AM EXPECTING NO MORE THAN 1 TO 4 INCHES OF SNOW ACROSS HERKIMER... HAMILTON...NORTHERN FULTON AND NORTHERN WARREN COUNTIES. ELSEWHERE...RAIN MAY CHANGE TO SNOW BEFORE PCPN ENDS AS WELL...BUT IT WILL OCCUR SO LATE THAT LITTLE IF ANY ACCUMULATION IS EXPECTED. AN INCH OR LESS HAS BEEN FORECAST IN THE CENTRAL MOHAWK VALLEY...THE SCHOHARIE VALLEY AND EASTERN CATSKILLS LATE TONIGHT...WITH LITTLE OR NO SNOW ELSEWHERE. NO WINTER WEATHER ADVISORIES HAVE BEEN ISSUED AT THIS TIME SINCE SNOWFALL AMOUNTS ARE LESS THAN THE ADVISORY CRITERIA. HOWEVER...SINCE WE HAVE BEEN HIGHLIGHTING THIS EVENT IN THE HWOALY PRODUCT FOR THE PAST FEW DAYS...CONTINUED TO MENTION THE SNOW ACCUMULATIONS IN THE LATEST HWOALY. MODEL WIND FORECASTS AT 925 MB AND 850 INDICATE SOUTHERLY WINDS AT THOSE LEVELS WILL INCREASE TO 40 TO 50 KTS LATE TODAY AND THIS EVENING. HOWEVER...MOS WIND FORECASTS AND MODEL SOUNDINGS INDICATE THAT THESE STRONG WINDS ARE NOT LIKELY TO TRANSLATE DOWN TO THE SURFACE DUE TO THE RAIN/PCPN INDUCED LOW LEVEL INVERSION THAT IS LIKELY TO DEVELOP AFTER THE PCPN BEGINS. DAY SHIFT WILL NEED TO MONITOR FOR THE POSSIBILITY THAT THE STRONG SOUTHERLY WINDS ALOFT MAY MIX DOWN TO THE SURFACE...ESPECIALLY IF ANY CONVECTIVE ELEMENTS BEGIN TO DEVELOP LATER TODAY AS THE PCPN APPROACHES. TEMPS TODAY WILL RISE INTO THE UPPER 30S AND 40S BY LATE IN THE DAY...AND GENERALLY REMAIN AT THOSE LEVELS UNTIL THE SURFACE LOW MOVES BY AND WESTERLY WINDS BRING COLDER AIR IN. THIS IS NOT LIKELY TO HAPPEN UNTIL AROUND OR AFTER 06Z TONIGHT. BY SUNRISE WEDNESDAY MORNING...TEMPS WILL EVENTUALLY DROP INTO THE 20S OVER THE NORTHWEST...AND 30S ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... TYPICAL BLUSTERY CONDITIONS WITH SCATTERED TO NUMEROUS SNOW SHOWERS ACROSS THE REGION ON WEDNESDAY IN THE WAKE OF THE STORM...ESPECIALLY OVER HIGHER TERRAIN AND DOWNWIND OF LAKE ONTARIO. ANOTHER INCH OR TWO OF SNOW IS POSSIBLE FROM THE ADIRONDACKS TO THE MOHAWK AND SCHOHARIE VALLEYS AND EASTERN CATSKILLS ON WEDNESDAY...WITH LESSER AMOUNTS ELSEWHERE. MODELS CONTINUE TO SHOW 925 AND 850 WINDS IN THE 40 TO 50 KT RANGE ON WEDNESDAY...BUT WITH THE MIXING OF THE NOW WEST TO NORTHWEST WINDS DOWN TO THE SURFACE MUCH MORE LIKELY...THERE IS A BETTER CHANCE THAT A WIND ADVISORY MAY BE NEEDED ON WEDNESDAY...AND IT HAS BEEN HIGHLIGHTED IN THE HWOALY PRODUCT ACROSS THE ENTIRE FORECAST AREA. HAVE CURRENTLY FORECAST WINDS OF 15 TO 30 MPH WITH GUSTS OF 35 TO 45 MPH. TEMPS WEDNESDAY MAY ACTUALLY FALL OR REMAIN STEADY AS COLDER AIR SURGES IN. HAVE INDICATED HIGHS ON WEDNESDAY ONLY ABOUT A DEGREE OR TWO HIGHER THAN THE LOWS WEDNESDAY MORNING. WINDS AND SNOW SHOWERS WILL DIMINISH WEDNESDAY EVENING. EXPECT LEFTOVER SNOW SHOWERS TO COMPLETELY END DURING THE EVENING...BUT A DECENT WIND WILL CONTINUE THROUGH THE NIGHT WITH WIND GUSTS OF 25 TO 30 MPH POSSIBLE THROUGH WELL AFTER MIDNIGHT. LOWS WEDNESDAY NIGHT WILL RANGE FROM A FEW DEGREES BELOW ZERO OVER THE ADIRONDACKS...TO THE UPPER TEENS OVER THE SOUTH. A CLIPPER LIKE SYSTEM WILL MOVE THROUGH THE GREAT LAKES ON THURSDAY...BUT IT IS NOT LIKELY TO ARRIVE IN OUR AREA UNTIL THURSDAY NIGHT. SO HAVE KEPT THE FORECAST FOR THURSDAY DRY...BUT DID INCREASE THE CLOUD COVER. HIGHS THURSDAY WILL BE IN THE 20S TO MID 30S. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... A CLIPPER TYPE LOW APPROACHES THE REGION THURSDAY NIGHT RESULTING IN CLOUDY SKIES...LOW CHANCE POPS...AND LOW TEMPS FROM AROUND 10 ABOVE NORTH TO THE UPPER 20S SOUTH. PRECIP AMOUNTS...ALL SNOW... WILL BE VERY LIGHT AS THE THE SYSTEM IS MOISTURE STARVED. THE CLIPPER MOVES ACROSS THE REGION ON FRIDAY. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF WHICH SLOWS DOWN THE MOVEMENT OF THE CLIPPER AND MOVES IT FARTHER SOUTH. WARMER AIR IS DRAWN IN AHEAD OF THE CLIPPER WHICH CHANGES THE PRECIP FROM SNOW TO RAIN OVER MUCH OF THE REGION AND INCREASES THE PRECIP AMOUNTS TO THE SOUTH OF THE RAIN SNOW LINE. HIGHS FRIDAY WILL RANGE FROM AROUND 30 NORTH TO THE LOW 40S SOUTH. THE PASSAGE OF THE CLIPPER WILL BE FOLLOWED BY A SURGE OF COLD AIR WITH 850 TEMPS AROUND MINUS 10 WITH LOWS FRIDAY NIGHT FROM THE HIGH SINGLES NORTH TO THE MID 20S SOUTH. WESTERLY WINDS WILL RESULT IN A CHANCE FOR SOME LAKE ENHANCED PRECIP WITH THE COLD ADVECTION WEST...ENOUGH FOR CHANCE POPS DOWN THE MOHAWK VALLEY AND ELEVATED TERRAIN WEST OF THE HUDSON VALLEY...WITH ONLY SLIGHT CHANCE POPS FARTHER EAST. HIGHS SATURDAY WILL RANGE FROM THE MID 20S TO AROUND 40. HIGH PRESSURE BRIEFLY CROSSES THE REGION SATURDAY INTO SATURDAY NIGHT AND WINDS BACK AROUND TO A SOUTHWESTERLY DIRECTION BRINGING WARMER AIR INTO THE REGION. LOWS SATURDAY NIGHT WILL RANGE FROM AROUND 20 NORTH TO 30 SOUTH. THE NEXT IN A SERIES OF CLIPPERS MOVES ACROSS CANADA NORTH OF THE REGION ON SUNDAY...BRINGING A MIXED BAG OF RAIN AND SNOW SHOWERS DEPENDING ON THE LATITUDE... ELEVATION...AND TIME OF DAY. HIGHS SUNDAY WILL RANGE FROM THE MID 30S NORTH TO THE LOWER 40S SOUTH. AS THE LOW MOVES EAST IT BRINGS ANOTHER BLAST OF COLD IN ITS WAKE...CHANGING THE RAIN TO SNOW SUNDAY EVENING. LOWS SUNDAY NIGHT WILL RANGE FROM THE LOWER TEENS TO THE MID 20S. MONDAY LOOKS TO BE BLUSTERY AND COLD WITH BRISK NORTHWEST WINDS 15 TO 25 MPH DURING THE MIDDAY PERIOD AND HIGHS ONLY FROM AROUND 20 NORTH TO THE UPPER 30S SOUTH. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... VFR FLIGHT CONDITIONS AND NO AVIATION WEATHER PROBLEMS ARE EXPECTED THROUGH MID TO LATE AFTERNOON. SCATTERED HIGH CLOUDS WILL THICKEN SOME AND LOWER DURING THE MORNING HOURS...WITH AN ALTOSTRATUS DECK AROUND 15000 FT ASL BY MID TO LATE MORNING. WINDS THIS MORNING WILL BE SOUTH 5 TO 10 KNOTS THIS MORNING AND MOST OF THE AFTERNOON. AS A LOW CENTER MOVES FROM THE OHIO VALLEY INTO THE MID ATLANTIC REGION THIS AFTERNOON...CONDITIONS WILL DETERIORATE LATER THIS AFTERNOON...WITH MVFR CONDITIONS AT BEST FOR THE EVENING HOURS AS RAIN OVERSPREADS THE REGION. THE CEILING AND VISIBLITY ARE LIKELY TO LOWER TO IFR DURING THE LATE EVENING HOURS AS THE BOUNDARY LAYER BECOMES MOISTER...WITH WINDS BECOMING SOUTHEAST DURING THE LATE AFTERNOON AND EARLY EVENING. WIDESPREAD IFR MAY BE EXPECTED DURING THE NIGHTTIME HOURS DUE TO LOW CEILINGS AND POOR VISIBILITY. SOME IMPROVEMENT TO MVFR MAY TAKE PLACE LATER TONIGHT AS THE STORM LIFTS NORTH INTO CANADA. LLWS MAY BECOME A FACTOR LATE THIS AFTERNOON AND EVENING AS WINDS 2000 TO 3000 FT AGL INCREASE TO 40-55 KTS. OUTLOOK... WED...MVFR...RAIN MIXING WITH SNOW AND TAPERING OFF TO SHWRS. WINDY. THU...VFR. NO SIG WX. FRI...VFR/MVFR...CHC -SHSN/-SHRA. && .HYDROLOGY... WHILE A SOAKING RAIN OF UP TO AROUND AN INCH IS EXPECTED THROUGH TONIGHT...IT IS NOT EXPECTED TO RESULT IN FLOODING. RAIN IS EXPECTED TO START LATE THIS AFTERNOON AND CONTINUE THROUGH TONIGHT. THE RAIN WILL MIX WITH AND CHANGE TO SNOW WELL NORTH AND WEST OF THE ALBANY AREA. HEAVIEST RAINFALL AMOUNTS ARE EXPECTED IN THE MID HUDSON REGION OF NEW YORK AND OVER THE HOUSATONIC VALLEY AND LITCHFIELD HILLS OF CONNECTICUT. MODEST RISES MAY BE EXPECTED ON THE RIVERS AND STREAMS IN THIS AREA...BUT THE RAIN IS NOT EXPECTED TO BE HEAVY ENOUGH TO BRING RIVERS UP TO FLOOD. DRY WEATHER ON THURSDAY WILL ALLOW RIVERS AND STREAMS TO RECEDE. A SERIES OF CLIPPER TYPE LOWS OVER THE NEW YEARS WEEKEND WILL HAVE LITTLE EFFECT ON THE RIVERS SINCE MOISTURE WILL BE LACKING WITH THEM. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...GJM/WASULA NEAR TERM...GJM/WASULA SHORT TERM...GJM LONG TERM...RCK AVIATION...RCK HYDROLOGY...RCK
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
706 AM EST TUE DEC 27 2011 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM WILL LIFT THROUGH THE SE THIS MORNING AND INTO THE CENTRAL APPALACHIANS AND VIRGINIA THIS AFTERNOON. A STRONG COLD FRONT TRAILING FROM THE LOW WILL PASS THROUGH LATE THIS MORNING AND THIS AFTERNOON. THE FRONT WILL BE PRECEDED BY WIDESPREAD SHOWERS AND A FEW STRONGER THUNDERSTORMS...RESULTING IN SOME MUCH NEEDED RAINFALL AND THE POSSIBILITY OF ISOLATED SEVERE WEATHER. HIGH PRESSURE WILL THEN BUILD INTO THE AREA TONIGHT THROUGH THURSDAY. A DRY COLD FRONT MAY MOVE IN LATE FRIDAY...BEFORE HIGH PRESSURE RETURNS FOR SATURDAY. ANOTHER COLD FRONT MAY AFFECT THE AREA EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A VERY ACTIVE NEAR TERM PERIOD IS ON TAP FOR TODAY WITH MULTIPLE HAZARDS EXPECTED TO AFFECT SOUTHERN SC/SOUTHEAST GA AND THE ADJACENT COASTAL WATERS. OVERALL...THERE ARE NO SIGNIFICANT CHANGES TO THE GENERAL THINKING ABOUT THE UPCOMING EVENT. THE MAIN CHANGES ARE FOR THE TIMING OF THE PRECIP THROUGH THE FORECAST AREA AND FOR UPDATES TO EXPECTED WINDS. AS HAS BEEN WELL DOCUMENTED IN PRECEDING FORECASTS...STRONG SYNOPTIC SCALE FORCING WILL MOVE ACROSS THE REGION TODAY. A POTENT CLOSED UPPER LOW OVER THE LOWER MS VALLEY WILL CONTINUE TO OPEN UP AND PHASE WITH NORTHERN STREAM ENERGY DIVING ACROSS THE UPPER MIDWEST. DIVERGENCE ALOFT ASSOCIATED WITH A 120 KT JET COMBINED WITH STRONG LOW LEVEL LINEAR FORCING ALONG A COLD FRONT WILL IS EXPECTED TO PUSH A BAND OF SHOWERS AND PERHAPS EMBEDDED THUNDERSTORMS ACROSS THE REGION. NOW LETS TAKE A LOOK AT A FEW ASPECTS OF THE EVENT. TIMING OF PRECIP...RECENT OPERATIONAL MODEL RUNS HAVE GREATLY SPED UP THE ARRIVAL OF THE APPROACHING SYSTEM. REGIONAL SATELLITE IMAGERY SHOWS ONGOING PRECIP SURROUNDING THE FORECAST AREA TO THE NW AND W WITH THE MAIN EVENTUAL CONVECTIVE LINE STARTING TO TAKE SHAPE OVER THE NE GULF AND FL PANHANDLE. THE 05Z HRRR SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT PRECIP COVERAGE AND EVOLUTION AND THE POP TREND FOR TODAY GENERALLY FOLLOWS IT. THE PRE FRONTAL LINE OF SHOWERS/CONVECTION WILL BEGIN PUSHING INTO THE FAR WESTERN PORTION OF THE FORECAST AROUND AROUND 12Z. I THEN TAKE THE AREA OF 100 POP AND MARCH IT EASTWARD WITH THE BAND ENTERING THE CHARLESTON AREA IN THE 14-15Z TIME FRAME. THE LINE OF SHOWERS AND/OR THUNDERSTORMS WILL BE PUSHING OFFSHORE BY THE LATE MORNING WITH JUST LINGERING SHOWERS INTO THE EARLY AFTERNOON FOR MOST OF THE AREA. SEVERE WEATHER POTENTIAL...THE DEEP LAYER WIND FIELDS ASSOCIATED WITH THIS SYSTEM CONTINUE TO LOOK QUITE IMPRESSIVE AND A HIGH SHEAR/LOW CAPE ENVIRONMENT IS ANTICIPATED. A POWERFUL 850 MB JET...ON THE ORDER OF 50-60 KTS...WILL TRAVERSE THE AREA THROUGH THE LATE MORNING RESULTING IN 0-3 KM WIND SHEAR OF 50 KTS OR MORE THROUGH THE LATE MORNING HOURS. SHEAR IS NOT THE PROBLEM WITH THIS SYSTEM AND THE LIMITING FACTOR FOR SEVERE WEATHER WILL BE INSTABILITY. GIVEN THAT THE SYSTEM IS EXPECTED TO MOVE THROUGH EARLIER IN THE DAY THAN WITH PREVIOUS FORECASTS...THE TIME WINDOW FOR DESTABILIZATION IS QUITE SHORT. IN FACT...WITH ONGOING PRECIP AND DENSE CLOUD COVER...IT WILL BE DIFFICULT TO GET MUCH IN THE WAY OF SURFACE BASED INSTABILITY. MODELS DO HINT AT A TIME IN THE LATE MORNING WHERE INSTABILITY COULD DEVELOP AND PRIMARILY OVER THE TRI COUNTY AREA AND ALONG THE IMMEDIATE COAST. GIVEN THE STRONGLY SHEARED AND WEAKLY UNSTABLE ENVIRONMENT IN THE PRESENCE OF STRONG LINEAR FORCING...THE PRIMARY CONVECTIVE MODE WOULD BE LINE SEGMENTS CAPABLE OF PRODUCING DAMAGING WIND GUSTS. IN THE EVENT THAT THERE IS ENOUGH INSTABILITY...THERE COULD BE A BRIEF ISOLATED BROKEN S TYPE TORNADO. THE MAIN TIME PERIOD FOR POTENTIAL SEVERE WEATHER LOOKS TO BE BETWEEN 9AM AND 1PM. GUSTY WINDS...AS THE STRENGTHENING LOW LEVEL JET MOVES THROUGH THE AREA STRONG GUSTY WINDS WILL DEVELOP ACROSS PORTIONS OF THE AREA. I HAVE HOISTED A WIND ADVISORY WHICH INCLUDES THE TRI COUNTY AREA AND BEAUFORT/COASTAL COLLETON COUNTIES. MIXING (ALBEIT LIMITED) WILL BEGIN AROUND 13Z JUST AHEAD OF THE APPROACHING PRECIP BAND. AS IT DOES YOU ONLY HAVE TO GO UP TO 500-1000 FEET TO REACH WINDS IN THE 35-40 KT RANGE BASED ON MODEL SOUNDINGS. WIND GUSTS OF 40-45 MPH WILL BE POSSIBLE IN THE AFOREMENTIONED AREAS AND WILL EXTEND THE ADVISORY THROUGH THE LATE AFTERNOON AS WINDS WILL REMAIN ELEVATED IN THE SW TO W FLOW ONCE THE PRECIP BAND PASSES THROUGH. TEMPERATURES WILL CONTINUE TO RISE THIS MORNING AS A WARM FRONT PASSES THROUGH DURING THE NEXT FEW HOURS. UPPER 60S CAN BE EXPECTED RIGHT ALONG THE COAST FROM SAVANNAH TO CHARLESTON WITH LOW TO MID 60S FURTHER INLAND. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... TONIGHT...DEEP LOW PRESSURE OVER THE NE CONTINUES TO STRENGTHEN AS IT MOVES INTO SE CANADA OVERNIGHT. THE TRAILING COLD FRONT WILL HAVE SHIFTED INTO THE ATLANTIC BY NIGHTFALL OFF OUR COASTS...AND HIGH PRESSURE WILL STEADILY BUILD FROM THE WEST THROUGH THE NIGHT. STRONG COLD ADVECTION EARLY WILL SLACKEN OFF AFTER MIDNIGHT...KEEPING BREEZY CONDITIONS GOING UNTIL LATE EVENING OR THE OVERNIGHT HOURS. AS SKIES CLEAR OUT...TEMPS WILL DROP STEADILY...BOTTOMING OUT BETWEEN 35 AND 40 DEGREES MOST LOCALES. LAKE WINDS...ONCE THE WIND ADVISORY COMES DOWN FOR BERKELEY COUNTY IT WILL NEED TO BE REPLACED BY A WIND ADVISORY ON LAKE MOULTRIE TONIGHT...AS COLD ADVECTION MOVING ACROSS THE WARMER LAKE WATERS WILL ALLOW FOR GOOD MIXING OF 20-30 KT WITHIN THE BOUNDARY LAYER. WEDNESDAY...A DRY WEST TO NW FLOW PREVAILS ALOFT...AS HIGH PRESSURE AT THE SURFACE MOVES IN FROM THE WEST. WEAK COLD ADVECTION IN THE MORNING WILL BE OFFSET BY DOWNSLOPE FLOW OFF THE MOUNTAINS AND PLENTY OF SUNSHINE...BUT WITH 850 MB TEMPS ONLY AROUND 2-3C NORTH AND 4-5C SOUTH...WE LOOK FOR MAX TEMPS MAINLY IN THE UPPER 50S. WEDNESDAY NIGHT IS THEN THE COLDEST NIGHT OF THE FORECAST PERIOD...AS THE HIGH SHIFTS CLOSER TO THE AREA AND GEOSTROPHIC WINDS FALL TO UNDER 10 KT. THIS ALLOWS FOR EXCELLENT RADIATIONAL COOLING AND WILL RESULT IN MIN TEMPS 30-35 INLAND FROM US-17...AND CLOSER TO 40 NEAR THE COAST. THURSDAY...HIGH PRESSURE SLIPS A LITTLE SOUTH AS A CLIPPER TYPE LOW PRESSURE SYSTEM MOVES THROUGH THE GREAT LAKES REGION. AFTER THE CHILLY START...ABUNDANT SUNSHINE AND DOWNSLOPE FLOW OFF THE APPALACHIANS WILL ALLOW FOR US TO TOP OUT WITHIN A COUPLE OF DEGREES EITHER SIDE OF 60. FRIDAY...AS THE LOW TO THE NORTH PUSHES EAST...A TRAILING COLD FRONT WILL MOVE APPROACH LATE IN THE DAY. BUT GIVEN THAT THE FLOW ALOFT IS GENERAL ZONAL AND ANY SHORT WAVE ENERGY REMAINS NORTH...THE FRONT LOOKS TO COME THROUGH DRY. COMPRESSIONAL HEATING AHEAD OF THE FRONT...AND OFFSHORE FLOW AND 850 MB TEMPS CLIMBING TO NEAR 9-10 C WILL BOOST AFTERNOON READINGS TO THE LOWER AND MIDDLE 60S. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... QUASI-ZONAL FLOW OR EVEN SHORT WAVE RIDGING ALOFT WILL PREVAIL LATE THIS WEEK...BEFORE THE PATTERN SHOWS SIGNS OF CHANGING EARLY NEXT WEEK. THE MID/UPPER SLOW WILL SEE THE FORMATION OF A TROUGH IN THE EAST AND RIDGING OUT WEST. THIS WILL ALLOW FOR SOME COLDER AIR TO INVADE THE EASTERN UNITED STATES...BUT TO WHAT MAGNITUDE HAS YET TO BE DETERMINED. AS THE PATTERN ALOFT TRANSITIONS OVER WE WILL SEE A COLD FRONT MOVING THROUGH EARLY NEXT WEEK...ALTHOUGH THERE ARE SOME TIMING UNCERTAINTIES AND AS TO WHETHER OR NOT IT WILL COME THROUGH DRY OR WITH SOME PRECIP. FOR NOW WE PREFER TO KEEP A DRY FORECAST GOING THROUGH TUESDAY...CAPPING POPS EARLY NEXT WEEK AT A SILENT 14 PERCENT. TEMPS WILL BE ABOVE NORMAL THROUGH THE WEEKEND...THEN TREND TOWARD BELOW NORMAL LEVELS MONDAY AND TUESDAY OR NEXT WEEK. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS EARLY IN THE TAF PERIOD WILL GIVE WAY TO PREVAILING MVFR WEATHER STARTING AROUND 1330-1430Z AT THE TERMINALS. THIS WILL RESULT FROM A WIDE BAND OF SHRA AND POSSIBLE TSRA IN ADVANCE OF A STRONG COLD FRONT THAT PUSHES THROUGH EARLY THIS AFTERNOON. IFR CONDITIONS CANNOT BE RULED OUT...BUT PROBABILITIES FAVOR MVFR WEATHER WILL PREVAIL. VFR CONDITIONS THEN RETURN IN WAKE OF THE COLD FRONT BEGINNING AROUND 1730-1830Z...AND WILL REMAIN VFR THROUGH 12Z WEDNESDAY. WINDS WILL BE OF GREAT CONCERN TODAY INTO TONIGHT WITH THE PASSAGE OF A STRONG LOW LEVEL JET...AS HIGH AS 45-55 KT THIS MORNING...AND 30-40 KT THIS AFTERNOON INTO TONIGHT. AS SUCH...BOTH TERMINALS WILL EXPERIENCE EITHER WIND SHEAR AND/OR STRONG GUSTY WINDS THROUGH MOST IF NOT THE ENTIRE TAF PERIOD. EXTENDED AVIATION OUTLOOK...VFR CONDITIONS WILL PREVAIL. && .MARINE... TODAY...AN AREA OF LOW PRESSURE WILL MOVE NORTHWARD INTO THE CENTRAL APPALACHIANS WITH A STRONG COLD FRONT MOVING INTO THE REGION THIS MORNING. AS IT DOES SO...A POWERFUL LOW LEVEL JET WITH PUSH ACROSS THE LOCAL WATERS SETTING UP THE CONDITIONS FOR A STRONG WIND EVENT. AFTER ANALYZING MODEL SOUNDINGS FOR THE LOCAL WATERS...CONFIDENCE HAS INCREASED SUFFICIENTLY TO UPGRADE THE SCA/S TO GALE WARNINGS FOR THE OUTER GA WATERS...THE NEARSHORE CHARLESTON WATERS...AND THE CHARLESTON HARBOR. FREQUENT GUSTS TO 35 KTS CAN BE EXPECTED IN THESE AREAS BEGINNING JUST AFTER SUNRISE AND CONTINUING THROUGH THE DAY. CONDITIONS WILL BE CLOSE TO GALE WARNING CRITERIA FOR THE REMAINDER OF THE NEARSHORE WATERS BUT CONFIDENCE ISN/T AS HIGH THERE. CONDITIONS WILL NEED TO MONITORED FOR POSSIBLE UPGRADES TO AMZ 352 AND 354. WINDS JUST AHEAD OF THE MAIN PRECIP BAND BE OUT OF THE S...WITH SOME EVEN HIGHER GUSTS POSSIBLE IN ANY THUNDERSTORMS THE DEVELOP WITHIN THE BAND. THE MAIN AREA OF PRECIP SHOULD CLEAR MOST OF THE WATERS BY THE EARLY AFTERNOON AND WINDS WILL BECOME MORE SW BEHIND IT. SEAS WILL BUILD THROUGH THE DAY AND WILL REACH UP TO 8 FEET CLOSE TO 20 NM ACROSS THE NEARSHORE CHARLESTON WATERS. CONCERNING A POSSIBLE HIGH SURF ADVISORY...IT STILL LOOKS LIKE THE DURATION OF SOUTHERLY FETCH WILL BE TOO SHORT TO MAKE AN ADVISORY NECESSARY. TONIGHT...COLD ADVECTION WILL INTENSIFY IN WAKE OF THE COLD FRONT AND DEPARTING LOW TO THE DISTANT NORTH...AND WE ARE LOOKING AT SOLID SCA/S FOR ALL WATERS FROM 0-20 NM AND IN THE CHARLESTON HARBOR. IT/LL BE CLOSE TO GALES ACROSS THESE WATERS...BUT IT LOOKS LIKE ANY FREQUENCY OF GUSTS WILL BE CLOSER TO 30 KT RATHER THAN 35 KT. ACROSS THE OUTER GA WATERS...ANY DECREASE IN WINDS THIS EVENING WILL ONLY BE TEMPORARY AS EXCELLENT MIXING ALLOWS FOR GALE FORCE GUSTS TO AGAIN ARRIVE ACROSS AMZ374. THE OFFSHORE FETCH WILL ALLOW FOR SEAS TO REMAIN UNDER 5 OR 6 FT WITHIN 20 NM OF SHORE...BUT WILL STILL REACH AS HIGH AS 8 OR 9 FT OUT NEAR 60 NM OFFSHORE. WEDNESDAY...MARINE CONDITIONS WILL RAPIDLY IMPROVE DURING THE MORNING AS COLD ADVECTION WANES AND THE PRESSURE GRADIENT BEGINS TO RELAX AS HIGH PRESSURE BUILDS IN FROM THE WEST. ALL HEADLINES WILL COME DOWN BY NO LATER THAN 10-11 AM. THURSDAY THROUGH FRIDAY...RELATIVELY QUIET CONDITIONS WILL PREVAIL WITH HIGH PRESSURE OVER OR JUST SOUTH OF THE MARINE AREA...AND A MAINLY OFFSHORE FLOW TO PREVAIL. A COLD FRONT LOOKS TO MOVE THROUGH LATE FRIDAY OR FRIDAY NIGHT. WINDS AND SEAS WILL BE NOWHERE NEAR ANY SCA CRITERIA. SATURDAY THROUGH SUNDAY...HIGH PRESSURE WILL BUILD FROM THE NORTH...AND THEN SLIDES EAST INTO THE ATLANTIC. ALTHOUGH AN OFFSHORE FLOW DEVELOPS...WIND SPEEDS WILL REACH NO MORE THAN 10 OR 15 KT...AND SEAS WILL BE LIMITED TO ONLY 2 OR 3 FT. MONDAY THROUGH TUESDAY...IT LOOKS LIKE ANOTHER COLD FRONT WILL IMPACT THE AREA EARLY NEXT WEEK...FOLLOWED BY STRONG HIGH PRESSURE FROM THE WEST AND NW. WINDS AND SEAS WILL RISE...AND ALTHOUGH PROBABILITIES ARE LOW...WE CAN/T RULE OUT THE POSSIBILITY OF SOME SCA/S WITHIN THE COLDER AIR REGIME. && .TIDES/COASTAL FLOODING... THE MORNING HIGH TIDE IN CHARLESTON WILL COME VERY CLOSE TO THE SHALLOW COASTAL FLOODING CRITERIA OF 7.0 FT MLLW. RECENT TRENDS OF THE TIDAL DEPARTURE SHOWS THAT LEVELS ARE RUNNING NEAR OR A LITTLE ABOVE 1.0 FT MLLW ABOVE PREDICTED. WITH THE PREDICTED TIDE OF 6.04 FT AT 944 AM...WE HAVE OPTED TO ISSUE A COASTAL FLOOD ADVISORY UNTIL 11 AM FOR CHARLESTON AND COASTAL COLLETON COUNTIES. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...WIND ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR SCZ044-045- 048>050-052. COASTAL FLOOD ADVISORY UNTIL 11 AM EST THIS MORNING FOR SCZ049- 050. MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST WEDNESDAY FOR AMZ352. GALE WARNING UNTIL 5 PM EST THIS AFTERNOON FOR AMZ330-350. SMALL CRAFT ADVISORY UNTIL 4 AM EST WEDNESDAY FOR AMZ354. GALE WARNING UNTIL 4 AM EST WEDNESDAY FOR AMZ374. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
241 PM CST TUE DEC 27 2011 .DISCUSSION... 1240 PM CST FOR UPDATE... HAVE MADE FEW CHANGES TO GOING FORECAST...AND THOSE MAINLY ONLY TO END LINGERING PRECIP FROM THE WEST ACROSS THE FAR EAST/SOUTHEAST PART OF THE CWA THIS MORNING. HAVE ALSO TWEAKED HOURLY/MAX TEMPS JUST A BIT...WITH SEVERAL LOCATIONS HAVING TAGGED 40 DEGREES IN THE PAST HOUR OR TWO. MAIN NEAR TERM CONCERNS ARE POTENTIAL FOR A FEW FLURRIES OR SPRINKLES THIS AFTERNOON...AS WELL AS THE POTENTIAL FOR A LITTLE LIGHT LAKE EFFECT PRECIPITATION TO DEVELOP THIS AFTERNOON INTO THIS EVENING FOR NORTHWEST INDIANA. UPPER TROUGH CONTINUES TO DEEPEN THIS AFTERNOON AS VORT DIGS SOUTHEAST ACROSS THE MID-MISSISSIPPI VALLEY. IN THE LOW LEVELS... COLD ADVECTION BEGINNING TO STRENGTHEN WHICH WILL LEAD TO STEEPENING OF LOW LEVEL LAPSE RATES IN SHALLOW MOIST LAYER BELOW ABOUT 850 HPA. COMBINATION OF WEAK DPVA ALOFT AND WEAK LOW LEVEL INSTABILITY IN CYCLONIC LOW LEVEL FLOW IS EXPECTED TO SUPPORT POTENTIAL FOR A FEW FLURRIES OR SPRINKLES ACROSS THE AREA THROUGH THE AFTERNOON. REGIONAL RADAR MOSAIC INDEED SHOWS SOME VERY WEAK RETURNS MOVING SOUTH ACROSS PORTIONS OF EASTERN WI. FORECAST SOUNDINGS INDICATE TOP OF MOIST LAYER ROUGHLY -8 TO -10 C...SO EITHER P-TYPE OF --RA OR --S POSSIBLE. VORT AXIS SHIFTS EAST OF THE AREA EARLY THIS EVENING WITH DRYING AND SUBSIDENCE BRINGING AN END TO ANY LINGERING LIGHT PCPN. LAKE EFFECT POTENTIAL IS NOT OVERLY IMPRESSIVE...THOUGH PREVIOUSLY MENTIONED PROCESSES ARE EXPECTED TO GRADUALLY INCREASE LAKE TO 850 DELTA T VALUES TO 16/17 DEG/KM THIS EVENING. LOCAL HIGH-RES WRF DEPICTS A BRIEF PERIOD OF LOW LEVEL CONVERGENCE ALONG THE SOUTH SHORE OF THE LAKE EARLY THIS EVENING...BEFORE MOIST CONVERGENCE AXIS SHIFTS EAST OF PORTER COUNTY. LIGHT QPF OUTPUT OVER MAINLY NORTHERN PORTER COUNTY SUGGESTS A LITTLE MINOR ACCUMULATION POSSIBLE...BUT WINDOW WILL PROBABLY BE FAIRLY SHORT BETWEEN DEVELOPMENT OF BETTER LAKE-INDUCED LAPSE RATES AND BEST CONVERGENCE SHIFTING EAST. RATZER //PREV DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * GUSTY NNW WINDS THIS AFTERNOON AND EVENING. * CIG TRENDS THROUGH THE DAY...TIMING LOW LEVEL MOISTURE CLEARING OUT THIS EVENING. * CHANCES FOR FLURRIES THIS AFTERNOON. BMD //DISCUSSION...UPDATED 18Z... COLD FRONT HAS SLID SOUTHEAST THROUGH THE FORECAST AREA WITH WINDS CHANGING TO THE NW/NNW BEHIND. UPSTREAM OBSERVATIONS SHOW DRY AIR AND GUSTY WINDS PUSHING SOUTHEAST BEHIND THE FRONT AND HELPING TO SCOUR OUT SOME OF THE LOW LEVEL MOISTURE. UPSTREAM STRATUS DECK/CIGS WHICH WERE MVFR HAVE GENERALLY IMPROVED TO VFR AND LENDS TO INCREASED CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL ACROSS NORTHERN ILLINOIS THROUGH THE REMAINDER OF THE DAY. COLD ADVECTION INTO THE AREA WILL STEEPEN LOW LEVEL LAPSE RATES ALLOWING FOR DEEP MIXING THIS AFTERNOON. FORECAST SOUNDINGS CONTINUE TO INDICATE WIND GUSTS WILL INCREASE INTO THE UPPER 20KT RANGE WITH OCCASIONAL 30KT GUSTS NOT OUTSIDE THE REALM OF POSSIBILITY. VERY SHALLOW LOW LEVEL INSTABILITY IS ALSO INDICATED BY THE FORECAST SOUNDINGS AND CANNOT RULE OUT A FEW FLURRIES DEVELOPING THIS AFTERNOON...MAINLY IN THE 20Z-23Z WINDOW. SOME LIGHT RETURNS ARE ALREADY SHOWING UP ON RADAR ACROSS WEST/SOUTHWEST WISCONSIN LATE THIS MORNING. NO ACCUMULATIONS ARE EXPECTED...NOR ANY VIS RESTRICTIONS. LOW LEVEL MOISTURE WILL CONTINUE TO ERODE THROUGH THE EVENING AS SURFACE RIDGE BEGINS TO WORK IN FROM THE WEST. BY WEDNESDAY...WINDS WILL BEGIN TO BACK TO THE WEST AND WEAKEN AS HIGH PRESSURE BUILDS ACROSS THE REGION. BMD //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON SPEEDS/GUSTS AND TIMING. * MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON...WITH NO IMPACTS TO VIS. HIGH CONFIDENCE IN NO ACCUMULATION. * MEDIUM CONFIDENCE IN CIG TRENDS. BMD //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 239 PM CST THE AREA OF LOW PRESSURE HAS MOVED OVER OHIO...BUT PRESSURE RISES AND A TIGHT PRESSURE GRADIENT BEHIND THE LOW HAS CAUSED WINDS TO STRENGTHEN THROUGHOUT THE DAY TODAY. GALES TO 45 KT ARE POSSIBLE THROUGH THE EARLY PART OF TONIGHT ACROSS THE ENTIRE LAKE. AS THE LOW MOVES NORTHWARD THROUGH THE NEW ENGLAND AREA TONIGHT...THE PRESSURE GRADIENT WILL WEAKEN AND WINDS WILL DIMINISH. HIGH PRESSURE ALSO MOVES IN BEHIND THE LOW ON WEDNESDAY...WHICH WILL ALSO HELP WINDS WEAKEN QUICKLY. WAVES ON THE OTHER HAND WILL REMAIN HIGH ESPECIALLY OVER THE SOUTHERN HALF OF THE LAKE AND IN THE NORTHERN INDIANA NEARSHORE ZONES THROUGH EARLY WEDNESDAY AFTERNOON. A WEAKENING CLIPPER SYSTEM WILL MOVE INTO NORTH DAKOTA WEDNESDAY NIGHT AND REACH LAKE MICHIGAN THURSDAY AFTERNOON. THE PRESSURE GRADIENT LOOKS VERY WEAK WITH THIS SYSTEM...THEREFORE NOT ANTICIPATING GALES. A WEAK RIDGE OF HIGH PRESSURES QUICKLY PASSES THROUGH REGION FRIDAY NIGHT INTO SATURDAY MORNING. THE PATTERN REMAINS ACTIVE THROUGH THE LONG TERM...WITH THE NEXT CHANCE FOR GALES LATE THIS WEEKEND INTO EARLY NEXT WEEK AS A LARGE LOW PRESSURE SYSTEM PASSES NORTH OF THE GREAT LAKES. JEE && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
202 PM CST TUE DEC 27 2011 .DISCUSSION... 1240 PM CST FOR UPDATE... HAVE MADE FEW CHANGES TO GOING FORECAST...AND THOSE MAINLY ONLY TO END LINGERING PRECIP FROM THE WEST ACROSS THE FAR EAST/SOUTHEAST PART OF THE CWA THIS MORNING. HAVE ALSO TWEAKED HOURLY/MAX TEMPS JUST A BIT...WITH SEVERAL LOCATIONS HAVING TAGGED 40 DEGREES IN THE PAST HOUR OR TWO. MAIN NEAR TERM CONCERNS ARE POTENTIAL FOR A FEW FLURRIES OR SPRINKLES THIS AFTERNOON...AS WELL AS THE POTENTIAL FOR A LITTLE LIGHT LAKE EFFECT PRECIPITATION TO DEVELOP THIS AFTERNOON INTO THIS EVENING FOR NORTHWEST INDIANA. UPPER TROUGH CONTINUES TO DEEPEN THIS AFTERNOON AS VORT DIGS SOUTHEAST ACROSS THE MID-MISSISSIPPI VALLEY. IN THE LOW LEVELS... COLD ADVECTION BEGINNING TO STRENGTHEN WHICH WILL LEAD TO STEEPENING OF LOW LEVEL LAPSE RATES IN SHALLOW MOIST LAYER BELOW ABOUT 850 HPA. COMBINATION OF WEAK DPVA ALOFT AND WEAK LOW LEVEL INSTABILITY IN CYCLONIC LOW LEVEL FLOW IS EXPECTED TO SUPPORT POTENTIAL FOR A FEW FLURRIES OR SPRINKLES ACROSS THE AREA THROUGH THE AFTERNOON. REGIONAL RADAR MOSAIC INDEED SHOWS SOME VERY WEAK RETURNS MOVING SOUTH ACROSS PORTIONS OF EASTERN WI. FORECAST SOUNDINGS INDICATE TOP OF MOIST LAYER ROUGHLY -8 TO -10 C...SO EITHER P-TYPE OF --RA OR --S POSSIBLE. VORT AXIS SHIFTS EAST OF THE AREA EARLY THIS EVENING WITH DRYING AND SUBSIDENCE BRINGING AN END TO ANY LINGERING LIGHT PCPN. LAKE EFFECT POTENTIAL IS NOT OVERLY IMPRESSIVE...THOUGH PREVIOUSLY MENTIONED PROCESSES ARE EXPECTED TO GRADUALLY INCREASE LAKE TO 850 DELTA T VALUES TO 16/17 DEG/KM THIS EVENING. LOCAL HIGH-RES WRF DEPICTS A BRIEF PERIOD OF LOW LEVEL CONVERGENCE ALONG THE SOUTH SHORE OF THE LAKE EARLY THIS EVENING...BEFORE MOIST CONVERGENCE AXIS SHIFTS EAST OF PORTER COUNTY. LIGHT QPF OUTPUT OVER MAINLY NORTHERN PORTER COUNTY SUGGESTS A LITTLE MINOR ACCUMULATION POSSIBLE...BUT WINDOW WILL PROBABLY BE FAIRLY SHORT BETWEEN DEVELOPMENT OF BETTER LAKE-INDUCED LAPSE RATES AND BEST CONVERGENCE SHIFTING EAST. RATZER //PREV DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * GUSTY NNW WINDS THIS AFTERNOON AND EVENING. * CIG TRENDS THROUGH THE DAY...TIMING LOW LEVEL MOISTURE CLEARING OUT THIS EVENING. * CHANCES FOR FLURRIES THIS AFTERNOON. BMD //DISCUSSION...UPDATED 18Z... COLD FRONT HAS SLID SOUTHEAST THROUGH THE FORECAST AREA WITH WINDS CHANGING TO THE NW/NNW BEHIND. UPSTREAM OBSERVATIONS SHOW DRY AIR AND GUSTY WINDS PUSHING SOUTHEAST BEHIND THE FRONT AND HELPING TO SCOUR OUT SOME OF THE LOW LEVEL MOISTURE. UPSTREAM STRATUS DECK/CIGS WHICH WERE MVFR HAVE GENERALLY IMPROVED TO VFR AND LENDS TO INCREASED CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL ACROSS NORTHERN ILLINOIS THROUGH THE REMAINDER OF THE DAY. COLD ADVECTION INTO THE AREA WILL STEEPEN LOW LEVEL LAPSE RATES ALLOWING FOR DEEP MIXING THIS AFTERNOON. FORECAST SOUNDINGS CONTINUE TO INDICATE WIND GUSTS WILL INCREASE INTO THE UPPER 20KT RANGE WITH OCCASIONAL 30KT GUSTS NOT OUTSIDE THE REALM OF POSSIBILITY. VERY SHALLOW LOW LEVEL INSTABILITY IS ALSO INDICATED BY THE FORECAST SOUNDINGS AND CANNOT RULE OUT A FEW FLURRIES DEVELOPING THIS AFTERNOON...MAINLY IN THE 20Z-23Z WINDOW. SOME LIGHT RETURNS ARE ALREADY SHOWING UP ON RADAR ACROSS WEST/SOUTHWEST WISCONSIN LATE THIS MORNING. NO ACCUMULATIONS ARE EXPECTED...NOR ANY VIS RESTRICTIONS. LOW LEVEL MOISTURE WILL CONTINUE TO ERODE THROUGH THE EVENING AS SURFACE RIDGE BEGINS TO WORK IN FROM THE WEST. BY WEDNESDAY...WINDS WILL BEGIN TO BACK TO THE WEST AND WEAKEN AS HIGH PRESSURE BUILDS ACROSS THE REGION. BMD //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON SPEEDS/GUSTS AND TIMING. * MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON...WITH NO IMPACTS TO VIS. HIGH CONFIDENCE IN NO ACCUMULATION. * MEDIUM CONFIDENCE IN CIG TRENDS. BMD //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1240 PM CST TUE DEC 27 2011 .DISCUSSION... 1240 PM CST FOR UPDATE... HAVE MADE FEW CHANGES TO GOING FORECAST...AND THOSE MAINLY ONLY TO END LINGERING PRECIP FROM THE WEST ACROSS THE FAR EAST/SOUTHEAST PART OF THE CWA THIS MORNING. HAVE ALSO TWEAKED HOURLY/MAX TEMPS JUST A BIT...WITH SEVERAL LOCATIONS HAVING TAGGED 40 DEGREES IN THE PAST HOUR OR TWO. MAIN NEAR TERM CONCERNS ARE POTENTIAL FOR A FEW FLURRIES OR SPRINKLES THIS AFTERNOON...AS WELL AS THE POTENTIAL FOR A LITTLE LIGHT LAKE EFFECT PRECIPITATION TO DEVELOP THIS AFTERNOON INTO THIS EVENING FOR NORTHWEST INDIANA. UPPER TROUGH CONTINUES TO DEEPEN THIS AFTERNOON AS VORT DIGS SOUTHEAST ACROSS THE MID-MISSISSIPPI VALLEY. IN THE LOW LEVELS... COLD ADVECTION BEGINNING TO STRENGTHEN WHICH WILL LEAD TO STEEPENING OF LOW LEVEL LAPSE RATES IN SHALLOW MOIST LAYER BELOW ABOUT 850 HPA. COMBINATION OF WEAK DPVA ALOFT AND WEAK LOW LEVEL INSTABILITY IN CYCLONIC LOW LEVEL FLOW IS EXPECTED TO SUPPORT POTENTIAL FOR A FEW FLURRIES OR SPRINKLES ACROSS THE AREA THROUGH THE AFTERNOON. REGIONAL RADAR MOSAIC INDEED SHOWS SOME VERY WEAK RETURNS MOVING SOUTH ACROSS PORTIONS OF EASTERN WI. FORECAST SOUNDINGS INDICATE TOP OF MOIST LAYER ROUGHLY -8 TO -10 C...SO EITHER P-TYPE OF --RA OR --S POSSIBLE. VORT AXIS SHIFTS EAST OF THE AREA EARLY THIS EVENING WITH DRYING AND SUBSIDENCE BRINGING AN END TO ANY LINGERING LIGHT PCPN. LAKE EFFECT POTENTIAL IS NOT OVERLY IMPRESSIVE...THOUGH PREVIOUSLY MENTIONED PROCESSES ARE EXPECTED TO GRADUALLY INCREASE LAKE TO 850 DELTA T VALUES TO 16/17 DEG/KM THIS EVENING. LOCAL HIGH-RES WRF DEPICTS A BRIEF PERIOD OF LOW LEVEL CONVERGENCE ALONG THE SOUTH SHORE OF THE LAKE EARLY THIS EVENING...BEFORE MOIST CONVERGENCE AXIS SHIFTS EAST OF PORTER COUNTY. LIGHT QPF OUTPUT OVER MAINLY NORTHERN PORTER COUNTY SUGGESTS A LITTLE MINOR ACCUMULATION POSSIBLE...BUT WINDOW WILL PROBABLY BE FAIRLY SHORT BETWEEN DEVELOPMENT OF BETTER LAKE-INDUCED LAPSE RATES AND BEST CONVERGENCE SHIFTING EAST. RATZER && .PREV DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * GUSTY NNW WINDS THIS AFTERNOON AND EVENING. * CIGS TRENDS THROUGH THE DAY...TIMING LOW LEVEL MOISTURE CLEARING OUT LATE THIS EVENING. * CHANCES FOR FLURRIES THIS AFTERNOON. BMD //DISCUSSION...UPDATED 18Z... COLD FRONT HAS SLID SOUTHEAST THROUGH THE FORECAST AREA WITH WINDS CHANGING TO THE NW/NNW BEHIND. UPSTREAM OBSERVATIONS SHOW DRY AIR AND GUSTY WINDS PUSHING SOUTHEAST BEHIND THE FRONT AND HELPING TO SCOUR OUT SOME OF THE LOW LEVEL MOISTURE. UPSTREAM STRATUS DECK/CIGS WHICH WERE MVFR HAVE GENERALLY IMPROVED TO VFR AND LENDS TO INCREASED CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL ACROSS NORTHERN ILLINOIS THROUGH THE REMAINDER OF THE DAY. COLD ADVECTION INTO THE AREA WILL STEEPEN LOW LEVEL LAPSE RATES ALLOWING FOR DEEP MIXING THIS AFTERNOON. FORECAST SOUNDINGS CONTINUE TO INDICATE WIND GUSTS WILL INCREASE INTO THE UPPER 20KT RANGE WITH OCCASIONAL 30KT GUSTS NOT OUTSIDE THE REALM OF POSSIBILITY. VERY SHALLOW LOW LEVEL INSTABILITY IS ALSO INDICATED BY THE FORECAST SOUNDINGS AND CANNOT RULE OUT A FEW FLURRIES DEVELOPING THIS AFTERNOON...MAINLY IN THE 20Z-23Z WINDOW. SOME LIGHT RETURNS ARE ALREADY SHOWING UP ON RADAR ACROSS WEST/SOUTHWEST WISCONSIN LATE THIS MORNING. NO ACCUMULATIONS ARE EXPECTED...NOR ANY VIS RESTRICTIONS. LOW LEVEL MOISTURE WILL CONTINUE TO ERODE THROUGH THE EVENING AS SURFACE RIDGE BEGINS TO WORK IN FROM THE WEST. BY WEDNESDAY...WINDS WILL BEGIN TO BACK TO THE WEST AND WEAKEN AS HIGH PRESSURE BUILDS ACROSS THE REGION. BMD //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM TO HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE PERIOD. * HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON SPEEDS/GUSTS AND TIMING. * MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON...WITH NO IMPACTS TO VIS. HIGH CONFIDENCE IN NO ACCUMULATION. BMD //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1141 AM CST TUE DEC 27 2011 .DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * GUSTY NNW WINDS THIS AFTERNOON AND EVENING. * CIGS TRENDS THROUGH THE DAY...TIMING LOW LEVEL MOISTURE CLEARING OUT LATE THIS EVENING. * CHANCES FOR FLURRIES THIS AFTERNOON. BMD //DISCUSSION...UPDATED 18Z... COLD FRONT HAS SLID SOUTHEAST THROUGH THE FORECAST AREA WITH WINDS CHANGING TO THE NW/NNW BEHIND. UPSTREAM OBSERVATIONS SHOW DRY AIR AND GUSTY WINDS PUSHING SOUTHEAST BEHIND THE FRONT AND HELPING TO SCOUR OUT SOME OF THE LOW LEVEL MOISTURE. UPSTREAM STRATUS DECK/CIGS WHICH WERE MVFR HAVE GENERALLY IMPROVED TO VFR AND LENDS TO INCREASED CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL ACROSS NORTHERN ILLINOIS THROUGH THE REMAINDER OF THE DAY. COLD ADVECTION INTO THE AREA WILL STEEPEN LOW LEVEL LAPSE RATES ALLOWING FOR DEEP MIXING THIS AFTERNOON. FORECAST SOUNDINGS CONTINUE TO INDICATE WIND GUSTS WILL INCREASE INTO THE UPPER 20KT RANGE WITH OCCASIONAL 30KT GUSTS NOT OUTSIDE THE REALM OF POSSIBILITY. VERY SHALLOW LOW LEVEL INSTABILITY IS ALSO INDICATED BY THE FORECAST SOUNDINGS AND CANNOT RULE OUT A FEW FLURRIES DEVELOPING THIS AFTERNOON...MAINLY IN THE 20Z-23Z WINDOW. SOME LIGHT RETURNS ARE ALREADY SHOWING UP ON RADAR ACROSS WEST/SOUTHWEST WISCONSIN LATE THIS MORNING. NO ACCUMULATIONS ARE EXPECTED...NOR ANY VIS RESTRICTIONS. LOW LEVEL MOISTURE WILL CONTINUE TO ERODE THROUGH THE EVENING AS SURFACE RIDGE BEGINS TO WORK IN FROM THE WEST. BY WEDNESDAY...WINDS WILL BEGIN TO BACK TO THE WEST AND WEAKEN AS HIGH PRESSURE BUILDS ACROSS THE REGION. BMD //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM TO HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE PERIOD. * HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON SPEEDS/GUSTS AND TIMING. * MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON...WITH NO IMPACTS TO VIS. HIGH CONFIDENCE IN NO ACCUMULATION. BMD //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL NOON TUESDAY. GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1123 AM CST TUE DEC 27 2011 .DISCUSSION... ISSUED 1010 AM CST TUE DEC 27 2011 BULK OF THE MORNING PRECIPITATION HAS MOVED OUT OF THE AREA...WITH JUST SOME LIGHT SNOW LINGERING NEAR THE INDIANA BORDER. THIS SHOULD MOVE OUT OVER THE NEXT HOUR. BRIEF CLEAR SLOT IS QUICKLY FILLING IN AS A LARGE AREA OF STRATOCUMULUS DROPS SOUTHEAST ACROSS THE WESTERN CWA. HRRR SHOWING SOME SHOWERS DEVELOPING THIS AFTERNOON AS SECONDARY SHORTWAVE SWINGS ACROSS THE CWA...AND SOME CONVECTIVE TYPE ECHOES ARE CURRENTLY SHOWING UP ON BOTH LINCOLN AND DAVENPORT RADARS AS WELL AS VISIBLE SATELLITE IMAGERY. FORECAST SOUNDINGS NOT REALLY SHOWING ANY ICE CRYSTALS LEFT...SO WILL ONLY INCLUDE A MENTION OF SPRINKLES OR FLURRIES AT THIS TIME. SHOULD SEE TEMPERATURES BEGIN TO STEADY OUT OR FALL BY EARLY AFTERNOON... ESPECIALLY ACROSS THE WEST...AS COLDER AIR BEGINS TO FILTER IN BEHIND THE SHORTWAVE. UPDATED ZONES/GRIDS HAVE BEEN SENT. GEELHART && .AVIATION... ISSUED 1123 AM CST TUE DEC 27 2011 EARLIER CLEAR SLOT HAS BEEN FILLING BACK IN...WITH MVFR CLOUD CONDITIONS AT TIMES FROM KBMI-KDEC WESTWARD SLOWLY LIFTING INTO THE VFR RANGE. WILL INCLUDE SOME TEMPO PERIODS FOR THE FIRST COUPLE HOURS OF THE FORECAST FOR CEILINGS IN THE 2000-2500 FOOT RANGE. STILL HAVE SOME IFR CEILINGS LINGERING AT KCMI...BUT THESE SHOULD BE IMPROVING INTO VFR OR HIGH-END MVFR LEVELS VERY SOON. AN UPPER LEVEL WAVE WILL BE SWEEPING ACROSS CENTRAL ILLINOIS THIS AFTERNOON. THIS WILL SCATTER OUT THE CLOUDS EARLY THIS EVENING...AND GUSTY NORTHWEST WINDS WILL BEGIN TO DIMINISH. ANOTHER WEAK BOUNDARY WILL BE APPROACHING FROM THE NORTHWEST LATE IN THE NIGHT WITH SOME MID-LEVEL CLOUDINESS ABOVE 10KFT. NORTHWEST WINDS WILL GRADUALLY TURN TO THE SOUTHWEST AS A SURFACE RIDGE OF HIGH PRESSURE PUSHES ACROSS THE STATE EARLY WEDNESDAY MORNING. GEELHART && .PREV DISCUSSION... ISSUED 255 AM CST TUE DEC 27 2011 SHORT TERM...TODAY THROUGH THURSDAY LOW PRESSURE WILL TRACK FROM WESTERN TENNESSEE EARLY THIS MORNING INTO SOUTHERN OHIO BY MIDDAY...RESULTING IN A CONTINUATION OF LIGHT PRECIP ACROSS THE EASTERN HALF OF THE KILX CWA THROUGH THE MORNING. RADAR TRENDS SUGGEST BACK EDGE OF PRECIP WILL BE ALONG THE I-55 CORRIDOR BY 6 AM...THEN ALONG THE ILLINOIS/INDIANA BORDER BY NOON. A VARIETY OF PRECIP FELL ACROSS CENTRAL ILLINOIS LAST EVENING...WITH MANY REPORTS OF A RAIN/SNOW/SLEET MIXTURE. NAM FORECAST SOUNDINGS INDICATE FURTHER COOLING OF THE COLUMN OVER THE NEXT FEW HOURS... WHICH SHOULD RESULT IN PRECIP CHANGING TO MAINLY SNOW THIS MORNING. 08Z HOURLY OBS ARE BEGINNING TO SHOW THIS TREND...WITH SNOW NOW BEING REPORTED AT A NUMBER OF SITES ACROSS EAST-CENTRAL ILLINOIS. AS A RESULT...HAVE CARRIED CATEGORICAL POPS FOR SNOW ALONG/EAST OF I-57 THIS MORNING...WITH ACCUMULATIONS OF AN INCH OR LESS. HAVE TAPERED POPS TO JUST LOW CHANCE ALONG I-55...AND NOTHING FURTHER WEST. AS THE LOW PULLS AWAY AND AN APPROACHING COLD FRONT SWINGS THROUGH...GUSTY NORTHWESTERLY WINDS WILL DEVELOP DURING THE LATE MORNING INTO THE AFTERNOON. FORECAST SOUNDINGS SUGGEST SUSTAINED WINDS OF 10 TO 20 MPH...WITH GUSTS AS HIGH AS 30 MPH AT TIMES. DUE TO THE BRISK WINDS AND AMPLE CLOUD COVER...TEMPS WILL NOT WARM MUCH TODAY...WITH HIGHS ONLY CLIMBING INTO THE UPPER 30S TO AROUND 40 DEGREES. CHILLY WEATHER WILL BE IN STORE TONIGHT INTO WEDNESDAY...COURTESY OF HIGH PRESSURE SLIDING THROUGH THE REGION. OVERNIGHT LOWS WILL DIP INTO THE LOWER TO MIDDLE 20S...WHILE HIGHS ON WEDNESDAY REMAIN IN THE UPPER 30S AND LOWER 40S. W/NW UPPER FLOW WILL PREVAIL ACROSS THE CENTRAL/EASTERN CONUS THROUGH THURSDAY...WITH A NUMBER OF WEAK IMPULSES DROPPING THROUGH THE PREVAILING FLOW PATTERN. THE FIRST WAVE WILL TRACK ACROSS THE UPPER MIDWEST/GREAT LAKES WEDNESDAY NIGHT...WITH ANY ASSOCIATED PRECIP REMAINING WELL NORTH OF CENTRAL ILLINOIS. A SECOND STRONGER WAVE IS EXPECTED TO DIG A BIT FURTHER SOUTH THURSDAY NIGHT...POSSIBLY BRINGING LIGHT PRECIP AS FAR SOUTH AS THE I-74 CORRIDOR. THANKS TO A SOUTHERLY FLOW AHEAD OF THE SYSTEM...TEMPS WILL BE WARM ENOUGH TO SUPPORT A RAIN/SNOW MIX. THINK STRONGEST DYNAMICS WILL REMAIN ACROSS NORTHERN ILLINOIS...HOWEVER HAVE INCLUDED SLIGHT CHANCE POPS ALONG/NORTH OF I-74. LONG TERM...FRIDAY THROUGH MONDAY STILL QUITE A BIT OF MODEL DISCREPANCY IN THE EXTENDED...SO FORECAST CONFIDENCE REMAINS LOW BEYOND SATURDAY. ECMWF CONTINUES TO FEATURE AN AGGRESSIVELY DIGGING UPPER TROUGH ACROSS THE EASTERN CONUS EARLY NEXT WEEK...WHILE THE GFS IS MUCH LESS AMPLIFIED. GIVEN POOR AGREEMENT AND RUN-TO-RUN CONSISTENCY...HAVE OPTED TO LEAVE FORECAST DRY...ALTHOUGH IF ECMWF PANS OUT...PRECIP WOULD BE POSSIBLE ACROSS AT LEAST THE E/SE CWA SUNDAY INTO MONDAY. REGARDLESS OF WHICH MODEL TURNS OUT TO BE RIGHT...IT APPEARS A CHUNK OF COLDER AIR IS ON THE WAY FOR EARLY NEXT WEEK. IF THE ECMWF VERIFIES...TEMPS COULD BE WELL BELOW NORMAL. AT THIS TIME...WILL REMAIN CONSERVATIVE AND ONLY DROP TEMPS BACK DOWN TO NEAR NORMAL BY MONDAY. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1012 AM CST TUE DEC 27 2011 .DISCUSSION... ISSUED 1010 AM CST TUE DEC 27 2011 BULK OF THE MORNING PRECIPITATION HAS MOVED OUT OF THE AREA...WITH JUST SOME LIGHT SNOW LINGERING NEAR THE INDIANA BORDER. THIS SHOULD MOVE OUT OVER THE NEXT HOUR. BRIEF CLEAR SLOT IS QUICKLY FILLING IN AS A LARGE AREA OF STRATOCUMULUS DROPS SOUTHEAST ACROSS THE WESTERN CWA. HRRR SHOWING SOME SHOWERS DEVELOPING THIS AFTERNOON AS SECONDARY SHORTWAVE SWINGS ACROSS THE CWA...AND SOME CONVECTIVE TYPE ECHOES ARE CURRENTLY SHOWING UP ON BOTH LINCOLN AND DAVENPORT RADARS AS WELL AS VISIBLE SATELLITE IMAGERY. FORECAST SOUNDINGS NOT REALLY SHOWING ANY ICE CRYSTALS LEFT...SO WILL ONLY INCLUDE A MENTION OF SPRINKLES OR FLURRIES AT THIS TIME. SHOULD SEE TEMPERATURES BEGIN TO STEADY OUT OR FALL BY EARLY AFTERNOON... ESPECIALLY ACROSS THE WEST...AS COLDER AIR BEGINS TO FILTER IN BEHIND THE SHORTWAVE. UPDATED ZONES/GRIDS HAVE BEEN SENT. GEELHART && .AVIATION... ISSUED 518 AM CST TUE DEC 27 2011 UPPER LOW OVER NORTHERN MS WITH LARGE AREA OF MIXED PRECIPITATION EXTENDING NORTH THROUGH IL...MAINLY ALONG AND EAST OF INTERSTATE 55. BACK EDGE OF THE RAIN/SNOW IS MAKING STEADY PROGRESS AND WILL BE EAST OF SPI/BMI BY 13Z...DEC BY 14Z...AND CMI AROUND 16Z. A PERIOD OF CIGS BELOW 500 FT AND 3-5SM FOG WILL FOLLOW THE PRECIPITATION FOR A COUPLE OF HOURS...WITH TEMPORARY VFR CONDITIONS THEREAFTER. A COLD FRONT MOVING INTO EASTERN IA WILL MOVE THROUGH CENTRAL IL BEFORE 18Z. SATELLITE IMAGERY SHOWS ANOTHER BATCH OF MVFR STRATOCU MOVING SOUTHEAST INTO NORTHERN IA BEHIND THE FRONT...AND THE SHORT RANGE MODELS INDICATE THAT THESE CLOUDS WILL CONTINUE INTO CENTRAL IL. WINDS AFTER FRONTAL PASSAGE WILL INCREASE FROM THE NORTHWEST AT 20-25 KT WITH HIGHER GUSTS. UPSTREAM PROFILERS ARE SHOWING 925 MB WINDS OF 30-35 KT AT THIS TIME. CLOUDS WILL MOVE OUT AND WINDS WILL DIMINISH BETWEEN 00Z AND 03Z WED. AT THIS TIME...SIGNIFICANT FOG APPEARS UNLIKELY TONIGHT DUE TO THE DRIER SURFACE DEWPOINTS AND SUFFICIENT BREEZE TO KEEP THE AIR MIXED. 04 && .PREV DISCUSSION... ISSUED 255 AM CST TUE DEC 27 2011 SHORT TERM...TODAY THROUGH THURSDAY LOW PRESSURE WILL TRACK FROM WESTERN TENNESSEE EARLY THIS MORNING INTO SOUTHERN OHIO BY MIDDAY...RESULTING IN A CONTINUATION OF LIGHT PRECIP ACROSS THE EASTERN HALF OF THE KILX CWA THROUGH THE MORNING. RADAR TRENDS SUGGEST BACK EDGE OF PRECIP WILL BE ALONG THE I-55 CORRIDOR BY 6 AM...THEN ALONG THE ILLINOIS/INDIANA BORDER BY NOON. A VARIETY OF PRECIP FELL ACROSS CENTRAL ILLINOIS LAST EVENING...WITH MANY REPORTS OF A RAIN/SNOW/SLEET MIXTURE. NAM FORECAST SOUNDINGS INDICATE FURTHER COOLING OF THE COLUMN OVER THE NEXT FEW HOURS... WHICH SHOULD RESULT IN PRECIP CHANGING TO MAINLY SNOW THIS MORNING. 08Z HOURLY OBS ARE BEGINNING TO SHOW THIS TREND...WITH SNOW NOW BEING REPORTED AT A NUMBER OF SITES ACROSS EAST-CENTRAL ILLINOIS. AS A RESULT...HAVE CARRIED CATEGORICAL POPS FOR SNOW ALONG/EAST OF I-57 THIS MORNING...WITH ACCUMULATIONS OF AN INCH OR LESS. HAVE TAPERED POPS TO JUST LOW CHANCE ALONG I-55...AND NOTHING FURTHER WEST. AS THE LOW PULLS AWAY AND AN APPROACHING COLD FRONT SWINGS THROUGH...GUSTY NORTHWESTERLY WINDS WILL DEVELOP DURING THE LATE MORNING INTO THE AFTERNOON. FORECAST SOUNDINGS SUGGEST SUSTAINED WINDS OF 10 TO 20 MPH...WITH GUSTS AS HIGH AS 30 MPH AT TIMES. DUE TO THE BRISK WINDS AND AMPLE CLOUD COVER...TEMPS WILL NOT WARM MUCH TODAY...WITH HIGHS ONLY CLIMBING INTO THE UPPER 30S TO AROUND 40 DEGREES. CHILLY WEATHER WILL BE IN STORE TONIGHT INTO WEDNESDAY...COURTESY OF HIGH PRESSURE SLIDING THROUGH THE REGION. OVERNIGHT LOWS WILL DIP INTO THE LOWER TO MIDDLE 20S...WHILE HIGHS ON WEDNESDAY REMAIN IN THE UPPER 30S AND LOWER 40S. W/NW UPPER FLOW WILL PREVAIL ACROSS THE CENTRAL/EASTERN CONUS THROUGH THURSDAY...WITH A NUMBER OF WEAK IMPULSES DROPPING THROUGH THE PREVAILING FLOW PATTERN. THE FIRST WAVE WILL TRACK ACROSS THE UPPER MIDWEST/GREAT LAKES WEDNESDAY NIGHT...WITH ANY ASSOCIATED PRECIP REMAINING WELL NORTH OF CENTRAL ILLINOIS. A SECOND STRONGER WAVE IS EXPECTED TO DIG A BIT FURTHER SOUTH THURSDAY NIGHT...POSSIBLY BRINGING LIGHT PRECIP AS FAR SOUTH AS THE I-74 CORRIDOR. THANKS TO A SOUTHERLY FLOW AHEAD OF THE SYSTEM...TEMPS WILL BE WARM ENOUGH TO SUPPORT A RAIN/SNOW MIX. THINK STRONGEST DYNAMICS WILL REMAIN ACROSS NORTHERN ILLINOIS...HOWEVER HAVE INCLUDED SLIGHT CHANCE POPS ALONG/NORTH OF I-74. LONG TERM...FRIDAY THROUGH MONDAY STILL QUITE A BIT OF MODEL DISCREPANCY IN THE EXTENDED...SO FORECAST CONFIDENCE REMAINS LOW BEYOND SATURDAY. ECMWF CONTINUES TO FEATURE AN AGGRESSIVELY DIGGING UPPER TROUGH ACROSS THE EASTERN CONUS EARLY NEXT WEEK...WHILE THE GFS IS MUCH LESS AMPLIFIED. GIVEN POOR AGREEMENT AND RUN-TO-RUN CONSISTENCY...HAVE OPTED TO LEAVE FORECAST DRY...ALTHOUGH IF ECMWF PANS OUT...PRECIP WOULD BE POSSIBLE ACROSS AT LEAST THE E/SE CWA SUNDAY INTO MONDAY. REGARDLESS OF WHICH MODEL TURNS OUT TO BE RIGHT...IT APPEARS A CHUNK OF COLDER AIR IS ON THE WAY FOR EARLY NEXT WEEK. IF THE ECMWF VERIFIES...TEMPS COULD BE WELL BELOW NORMAL. AT THIS TIME...WILL REMAIN CONSERVATIVE AND ONLY DROP TEMPS BACK DOWN TO NEAR NORMAL BY MONDAY. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1004 AM CST TUE DEC 27 2011 .DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * CIG TRENDS...POTENTIAL FOR MVFR CONDITIONS TO RETURN. * STRONG GUSTY NNW WINDS. * POSSIBILITY OF FLURRIES THIS AFTERNOON. BMD //DISCUSSION...UPDATED 12Z... AREAS OF RAIN AND MIXED RAIN/SNOW OVER THE CHICAGO METRO TERMINALS HAVE DECREASED IN SIZE AND MOVED TO THE EAST THROUGH THE EARLY MORNING HOURS AS THE LOW PRESSURE SYSTEM CENTERED OVER WESTERN KY MOVES TO THE NORTHEAST. AS THE PRECIPITATION ENDS CIGS MAY IMPROVE JUST A LITTLE BIT. BUT MORE SIGNIFICANT IMPROVEMENT WILL BE BEHIND A COLD FRONT THAT WILL MOVE ACROSS NORTHERN IL AND NORTHWEST IN THIS MORNING. THIS FRONT WILL TURN WINDS TO THE NORTHWEST AND INCREASE THE SPEEDS BY LATE MORNING. FLURRIES ARE POSSIBLE BEHIND THE FRONT IN THE COLDER AIR AT ALL THE TERMINALS THIS AFTERNOON. PAW //ORD AND MDW CONFIDENCE...UPDATED 16Z... * MEDIUM CONFIDENCE ON VFR CONDITIONS PREVAILING REMAINDER OF DAY. LOW CONFIDENCE ON MVFR CONDITIONS RETURNING. * HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON WIND SPEEDS/GUSTS AND TIMING ARRIVAL OF GUSTS. * LOW CONFIDENCE ON FLURRIES THIS AFTERNOON. BMD //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL NOON TUESDAY. GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
812 AM CST TUE DEC 27 2011 .DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * CIG TRENDS THIS MORNING AND AFTERNOON...TIMING WINDOW OF VFR CONDITIONS BEFORE HIGHER END MVFR CONDITIONS RETURN. * STRONG GUSTY NNW WINDS. * POSSIBILITY OF FLURRIES THIS AFTERNOON. BMD //DISCUSSION...UPDATED 12Z... AREAS OF RAIN AND MIXED RAIN/SNOW OVER THE CHICAGO METRO TERMINALS HAVE DECREASED IN SIZE AND MOVED TO THE EAST THROUGH THE EARLY MORNING HOURS AS THE LOW PRESSURE SYSTEM CENTERED OVER WESTERN KY MOVES TO THE NORTHEAST. AS THE PRECIPITATION ENDS CIGS MAY IMPROVE JUST A LITTLE BIT. BUT MORE SIGNIFICANT IMPROVEMENT WILL BE BEHIND A COLD FRONT THAT WILL MOVE ACROSS NORTHERN IL AND NORTHWEST IN THIS MORNING. THIS FRONT WILL TURN WINDS TO THE NORTHWEST AND INCREASE THE SPEEDS BY LATE MORNING. FLURRIES ARE POSSIBLE BEHIND THE FRONT IN THE COLDER AIR AT ALL THE TERMINALS THIS AFTERNOON. PAW //ORD AND MDW CONFIDENCE...UPDATED 14Z... * MEDIUM CONFIDENCE ON SOME WINDOW OF IFR CONDITIONS...LOW CONFIDENCE ON SPECIFIC TIMING. * HIGH CONFIDENCE THAT ONCE CIGS LIFT ABOVE 015...WILL STAY ABOVE 015. * HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON WIND SPEEDS/GUSTS. * LOW CONFIDENCE ON FLURRIES THIS AFTERNOON. BMD //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL NOON TUESDAY. GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...NOON TUESDAY TO 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
533 AM CST TUE DEC 27 2011 .DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 12Z... * TIMING OF PRECIPITATION ENDING AT MDW THIS MORNING. * POSSIBILITY OF FLURRIES THIS AFTERNOON. * IFR CIGS IMPROVING TO MVFR BY MID MORNING. * WIND SHIFT TO NORTHWEST MID MORNING. SPEED INCREASING AND BECOMING GUSTY BY LATE MORNING AND CONTINUING INTO THIS EVENING. PAW //DISCUSSION...UPDATED 12Z... AREAS OF RAIN AND MIXED RAIN/SNOW OVER THE CHICAGO METRO TERMINALS HAVE DECREASED IN SIZE AND MOVED TO THE EAST THROUGH THE EARLY MORNING HOURS AS THE LOW PRESSURE SYSTEM CENTERED OVER WESTERN KY MOVES TO THE NORTHEAST. AS THE PRECIPITATION ENDS CIGS MAY IMPROVE JUST A LITTLE BIT. BUT MORE SIGNIFICANT IMPROVEMENT WILL BE BEHIND A COLD FRONT THAT WILL MOVE ACROSS NORTHERN IL AND NORTHWEST IN THIS MORNING. THIS FRONT WILL TURN WINDS TO THE NORTHWEST AND INCREASE THE SPEEDS BY LATE MORNING. FLURRIES ARE POSSIBLE BEHIND THE FRONT IN THE COLDER AIR AT ALL THE TERMINALS THIS AFTERNOON. PAW //ORD AND MDW CONFIDENCE...UPDATED 12Z... * MEDIUM CONFIDENCE IN ALL PRECIPITATION. * MEDIUM CONFIDENCE IN TIMING OF IFR CIG IMPROVEMENT. * HIGH CONFIDENCE IN WIND TREND. PAW //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL NOON TUESDAY. GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...NOON TUESDAY TO 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
406 AM CST TUE DEC 27 2011 .DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 10Z... * LIGHT RAIN...POSSIBLY MIXED WITH LIGHT SNOW...ENDING AROUND SUNRISE. * POSSIBILITY FOR FLURRIES THIS AFTERNOON. * IFR CIGS ASSOCIATED WITH PRECIPITATION IMPROVING TO MVFR BY MID MORNING. * WIND SHIFT TO NROTHWEST MID MORNING. WIND INCREASING AND BECOMING GUSTY BY LATE MORNING AND CONTINUING INTO THIS EVENING. PAW //DISCUSSION...UPDATED 06Z... LIGHT RAIN CONTINUES TO DEVELOP/SPREAD ACROSS NORTHERN IL LATE THIS EVENING WITH THE BACK EDGE EXTENDING FROM ROUGHLY MKE TO MLI. THIS WILL SLOWLY MOVE EAST ACROSS THE TERMINALS OVERNIGHT. LOW PRESSURE CURRENTLY NEAR MEMPHIS WILL LIFT NORTH ACROSS THE OHIO VALLEY THROUGH TUESDAY MORNING. AS IT DOES...ADDITIONAL PRECIP WILL SPREAD ACROSS EASTERN IL AND NORTHWEST INDIANA...LIKELY MIXING WITH THEN BECOMING ALL SNOW. WHEN AND WHERE THIS CHANGE OVER OCCURS IS THE CHALLENGE AND TRENDS STILL SUPPORT THE BULK OF THE PRECIP REMAINING JUST SOUTHEAST OF THE TERMINALS. THUS HAVE MADE NO SIGNIFICANT CHANGES WITH PREVAILING LIGHT RAIN THROUGH THE NIGHT WITH THE POTENTIAL TO MIX WITH SNOW OVERNIGHT. CIGS STILL VFR ACROSS THE AREA BUT MVFR CIGS DEVELOPING ACROSS CENTRAL IL AND AS LIGHT RAIN CONTINUES TO FALL...EXPECT CIGS TO GRADUALLY LOWER INTO MVFR. CONFIDENCE OF EXACTLY WHEN CIGS LOWER TO MVFR IS NOT PARTICULARLY HIGH...LIKELY IN THE 08Z-11Z TIME PERIOD...AND THIS WILL LIKELY NEED TWEAKING WITH OVERNIGHT UPDATES. IFR CIGS STILL POSSIBLE AND MOST LIKELY AFTER SUNRISE AS PRECIP ENDS...BUT AHEAD OF AN APPROACHING COLD FRONT. THIS FRONT SHOULD HELP LIFT ANY IFR CIGS BACK TO MVFR BY MID/LATE MORNING. ONCE WINDS SHIFT TO THE NORTHWEST...SPEEDS/GUSTS SHOULD STEADILY INCREASE AND WITH A PUSH OF COLDER AIR BY EARLY AFTERNOON...COULD BE SOME FLURRIES OR SNOW SHOWERS. SKIES BEGIN TO CLEAR BY LATE AFTERNOON/EARLY EVENING...AS WINDS ALSO BEGIN TO DIMINISH. CMS //ORD AND MDW CONFIDENCE...UPDATED 10Z... * MEDIUM CONFIDENCE IN TIMING OF PRECIPITATION ENDING THIS MORNING. * MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON. * MEDIUM CONFIDENCE IN TIMING OF IFR CIG IMPROVEMENT. * HIGH CONFIDENCE IN WIND TREND. PAW //OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z... * WEDNESDAY...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY..SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. CMS && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...NOON TUESDAY TO 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
355 AM EST THU DEC 29 2011 .SHORT TERM... / TODAY THROUGH FRIDAY NIGHT / 08Z SFC ANALYSIS SHOWS A SFC LOW NEAR MSP WITH A WARM FRONT EXTENDING SE INTO EASTERN IA AND WC IL. THE ASSOCIATED LOW AMPLITUDE SHORTWAVE OVER THE UPPER MIDWEST WILL SHEAR OUT TOWARDS THE CENTRAL GREAT LAKES TODAY ALLOWING THE WARM FRONT TO SURGE NEWD INTO THE SRN GREAT LAKES. RATHER MODEST OVERRUNNING/ISENTROPIC UPGLIDE EXPECTED JUST AHEAD OF THIS WARM FRONT THIS MORNING INTO EARLY THIS AFTERNOON (40 KNOTS OF CROSS ISOBARIC FLOW ON THE I290 SFC). UPSTREAM OBS/MOSAIC RADAR AND THE BULK OF 00Z GUIDANCE SUGGEST THAT NORTHERN AREAS MAY SEE A BRIEF PERIOD (AN HOUR OR TWO) OF VERY LIGHT PCPN THIS MORNING INTO EARLY THIS AFTN...WITH THE BETTER CHANCES FOR MEASURABLE PCPN (A COUPLE HUNDREDTHS AT BEST) BEING ACROSS THE NORTH/NORTHEAST WITH MAINLY VIRGA SOUTHWEST. LATEST RUC SOUNDINGS AND SFC OBS CONTINUE TO SUPPORT A POSSIBLE LIGHT MIX OF FREEZING DRIZZLE/SNOW TO START...LIKELY TRANSITIONING TO A BRIEF PERIOD OF DRIZZLE. ANY FREEZING DRIZZLE/RAIN BTW 12-15Z MAY CREATE A FEW SLICK SPOTS ON AREA ROADS...MAINLY NORTH OF ROUTE 6. OTHERWISE...EXPECT WINDS WILL PICK UP AND VEER BEHIND THE FRONTAL BOUNDARY WITH GUSTS OF 20-25 KNOTS POSSIBLE. A MUCH MORE VIGOROUS SHORTWAVE NOW ACROSS THE PAC NW WILL DIG INTO THE MID MS VALLEY AND NRN OH VALLEY BY LATER TONIGHT AND FRIDAY. GFS/ECMWF AGREE ON 120-140 METER 500 MB HEIGHT FALLS WITH THIS FEATURE SUPPORTING A RATHER HEALTHY LOW LVL RESPONSE AND THETA-E ADV INTO THE AREA WITH PCPN FOCUSING ALONG A DEEPENING BAROCLINIC ZONE. A MODEL CONSENSUS FAVORS THE NORTHERN HALF OF THE FA FOR BEST CHANCES FOR MEASURABLE RAINFALL. AMOUNTS ARE FCST TO RANGE BETWEEN 0.20" AND 0.50" HERE. HIRES GUIDANCE IS A LITTLE FARTHER SOUTH WITH THE TRACK OF THIS SYSTEM SO DID CONTINUE WITH CHC/SLIGHT WORDING FOR SNOW IN THE FAR NORTH...WITH AREAS JUST NORTH OF THE FA IN A GOOD POSITION FOR A MODERATE SNOWFALL. OTHERWISE...TEMPS ARE FCST TO BE ABOVE NORMAL THIS PERIOD WITH ONLY MINOR TWEAKS MADE. && .LONG TERM... OVERALL LARGE SCALE PATTERN STILL EXPECTED TO BECOME MORE AMPLIFIED THROUGH THE LONG TERM WITH BRIEF ARCTIC INTRUSION STILL EXPECTED LATTER HALF OF WEEKEND INTO NEXT WEEK. MEDIUM RANGE MODELS REMAIN IN GOOD AGREEMENT ON LARGE SCALE WITH DIFFERENCES CONTINUING IN THE DETAILS. CR ALLBLEND LOADED AND COLLABORATED SOME TWEAKS TO TEMPS AND POPS. A QUIET START EXPECTED ON SATURDAY WITH WARM AIR ADVECTION AHEAD OF FIRST COLD FRONT AND TEMPERATURES RISING WELL ABOVE NORMAL FOR LATE DECEMBER. SHOULD SEE 40S ACROSS ENTIRE AREA FOR HIGHS WITH 50S NOT OUT OF QUESTION SOUTH AND WEST. WARM AIR ADVECTION CONTINUES FIRST HALF OF SATURDAY NIGHT WITH TEMPS STEADY OR SLOWLY RISING UNTIL INITIAL FRONTAL PASSAGE LATE. HAVE TRIED TO DETAIL THIS SCENARIO IN HOURLY GRIDS WITH STEADY TEMPS THROUGH 06Z THEN A SLOW FALL TOWARD 12Z. DETAIL DIFFERENCES AND COMPLICATIONS IN FORECAST BEGIN IN THIS SATURDAY NIGHT INTO SUNDAY TIME FRAME WITH STRENGTH AND TIMING OF COLD AIR ADVECTION AND ANY ASSOCIATED PCPN. 850MB TEMPS BEGIN TO FALL AFTER 06Z SUNDAY WITH 1000-850MB THICKNESSES FOLLOWING. MODELS SHOWING LITTLE IN WAY OF PCPN WITH THIS FRONT GIVEN POSITIVELY TILTED UPPER SYSTEM AND NO STRONG MOISTURE SURGE AHEAD OF IT. DEEPENING SURFACE LOW REMAINS WELL NORTH OF AREA WITH ONLY SUBTLE INDICATIONS OF SECONDARY LOW DEVELOPMENT ALONG FRONT BY A FEW MODELS. HAVE THEREFORE ALLOWED LOW CHANCE POPS TO RIDE SAT NIGHT AND SUNDAY MORNING. SUNDAY BEGINNING TO LOOK DRY IN WAKE OF INITIAL COLD FRONT WITH SOME SUNSHINE EVEN POSSIBLE IN DRY SLOT BEFORE SECONDARY ARCTIC FRONT LATER IN THE DAY. IF THIS OCCURS...FALLING TEMPS EARLY IN THE MORNING MAY BECOME STEADY OR EVEN RISE A FEW DEGREES BEFORE SECONDARY FRONT BRINGS MUCH COLDER AIR IN DURING THE AFTERNOON. FOR NOW HAVE CHOSEN TO GO WITH SLOWLY FALLING TEMPS DURING THE DAY GIVEN TEMPS LOOK TO FALL IN THE AFTERNOON REGARDLESS. WITH ARCTIC INTRUSION SUNDAY NIGHT WILL SEE BEST LAKE EFFECT SNOW POTENTIAL OF THE SEASON AS DELTA T VALUES CLIMB WITH SURFACE TO 850MB WELL INTO LOWER 20S. SURFACE TO 700MB DELTA T VALUES REACH CRITICAL 30C THRESHOLD WHICH IS A GOOD INDICATOR OF HEAVY SNOW POTENTIAL. LIMITING FACTOR CONTINUES TO BE MOISTURE PROFILES BUT MEDIUM RANGE MODELS ARE SHOWING SOME DECENT SYNOPTIC MOISTURE LATE SUNDAY NIGHT THROUGH MONDAY WHICH WOULD SUPPORT A PERIOD OF HEAVY LAKE EFFECT SNOW BANDS. NORTHWEST FLOW AND WIND FIELD SUGGEST MULTI-BANDED EVENT WHICH MAKES PINNING DOWN AMOUNTS AND LOCATIONS DIFFICULT AT THIS TIME PROJECTION. HAVE BUMPED NW FETCH FAVORED AREAS INTO LIKELY CATEGORY FOR NOW. HEADLINES POSSIBLE LATER THIS WEEKEND INTO EARLY NEXT WEEK AS MOISTURE PROFILES BECOME BETTER DEFINED BY HIGHER RESOLUTION MODELS. && .AVIATION... / 06Z TAFS / WARM FRONT ASSOCIATED WITH AN APPROACHING SHORTWAVE TROUGH ACROSS THE UPPER MIDWEST WILL MIX NEWD THROUGH THE FA THIS MORNING ALLOWING WINDS TO VEER AND GUSTY BY LATE MORNING/AFTN. UPPER MIDWEST RADAR MOSAIC AND SFC OBS SHOW A NARROW BAND OF LIGHT RAIN IN AREA OF STRONG ISENTROPIC UPGLIDE ALONG WARM FRONT. EXPECT THIS FORCING AND SATURATION TO PROPAGATE THROUGH THE LOCAL AREA LATER THIS MORNING. 00Z MODEL SOUNDINGS CONTINUE TO SUPPORT PCPN MAINLY IN THE LIQUID FORM...WITH A PERIOD OF -FZRA/FZDZ POSSIBLE AT SBN BEFORE SFC TEMPS WARM ABOVE FREEZING BY 14/15Z. LESSER CHANCES OF PCPN AT FWA SO CONTINUED WITH PROB30 MENTION HERE. ALSO OPTED FOR -RA/DZ WORDING IN PROB30 INSTEAD OF FZDZ AS SFC TEMPS LOOK TO WARM JUST ABOVE FREEZING BY THE TIME FORCING/TOP DOWN SATURATION WORKS IN. OTHERWISE...CIGS WILL LIKELY LOWER TO MVFR FOR A TIME ALONG THE AFOREMENTIONED FRONTAL BOUNDARY WITH IMPROVED MIXING IN ITS WAKE SUPPORTING VFR CIGS BY THIS AFTN/EVE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 11 PM EST THIS EVENING FOR LMZ043. SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 5 PM EST THIS AFTERNOON FOR LMZ046. && $$ SHORT TERM...STEINWEDEL LONG TERM...LASHLEY AVIATION...STEINWEDEL
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1222 AM EST THU DEC 29 2011 .AVIATION... / 06Z TAFS / WARM FRONT ASSOCIATED WITH AN APPROACHING SHORTWAVE TROUGH ACROSS THE UPPER MIDWEST WILL MIX NEWD THROUGH THE FA THIS MORNING ALLOWING WINDS TO VEER AND GUSTY BY LATE MORNING/AFTN. UPPER MIDWEST RADAR MOSAIC AND SFC OBS SHOW A NARROW BAND OF LIGHT RAIN IN AREA OF STRONG ISENTROPIC UPGLIDE ALONG WARM FRONT. EXPECT THIS FORCING AND SATURATION TO PROPAGATE THROUGH THE LOCAL AREA LATER THIS MORNING. 00Z MODEL SOUNDINGS CONTINUE TO SUPPORT PCPN MAINLY IN THE LIQUID FORM...WITH A PERIOD OF -FZRA/FZDZ POSSIBLE AT SBN BEFORE SFC TEMPS WARM ABOVE FREEZING BY 14/15Z. LESSER CHANCES OF PCPN AT FWA SO CONTINUED WITH PROB30 MENTION HERE. ALSO OPTED FOR -RA/DZ WORDING IN PROB30 INSTEAD OF FZDZ AS SFC TEMPS LOOK TO WARM JUST ABOVE FREEZING BY THE TIME FORCING/TOP DOWN SATURATION WORKS IN. OTHERWISE...CIGS WILL LIKELY LOWER TO MVFR FOR A TIME ALONG THE AFOREMENTIONED FRONTAL BOUNDARY WITH IMPROVED MIXING IN ITS WAKE SUPPORTING VFR CIGS BY THIS AFTN/EVE. && .PREV DISCUSSION... /ISSUED 730 PM EST WED DEC 28 2011/ UPDATE... NEXT CLIPPER SYSTEM LOOKS TO IMPACT THE AREA VERY LATE TONIGHT INTO THURSDAY MORNING. STRENGTHENING WESTERLY LOW LEVEL FLOW LATER TONIGHT IN ADVANCE OF THIS FEATURE WILL BEGIN TO ADVECT WARMER LOW LEVEL AIR EASTWARD. POSITIVE LOW LEVEL THEATE ADVECTION ALREADY UNDERWAY ACROSS THE LOCAL AREA EARLY THIS EVENING...ALTHOUGH AIR MASS INITIALLY OVER THE AREA IS QUITE DRY AND MOISTURE AVAILABILITY REMAINS THE PRIMARY LIMITING FACTOR TO PRECIPITATION AMOUNTS WITH THIS CLIPPER. ONLY CHANGE THAT WILL BE MADE TO PREVIOUS FORECAST WILL BE TO ADD SLIGHT CHANCE MENTION OF LIGHT FREEZING RAIN IN THE 11Z TO 15Z TIMEFRAME. DESPITE WARM ADVECTION OVERNIGHT...SHOULD MAINTAIN ENOUGH OF A SHALLOW COLD LAYER TO PROVIDE A BRIEF WINDOW OF SOME LIGHT FREEZING PRECIPITATION. LINGERING SNOWCOVER ACROSS PORTIONS OF THE AREA MAY ALSO AID IN KEEPING LOW LEVEL TEMPS AT OR BELOW FREEZING FOR A LONGER DURATION EARLY THURSDAY MORNING. SOME LOWER CONFIDENCE STILL EXISTS HOWEVER...WITH SOME CONCERNS THAT MOISTURE AVAILABILITY CONCERNS COULD BE MANIFESTED IN PROFILES TOO DRY FOR PRECIP WHILE A THERMODYANAMIC PROFILE SUPPORTIVE OF FREEZING RAIN EXISTS. GIVEN THIS LOWER CONFIDENCE AND EXPECTED LIGHT PRECIP AMOUNTS WILL NOT BE ISSUING ANY HEADLINES BUT WILL LIKELY ISSUE AN SPS ADDRESSING THE CHANCE OF A BRIEF PERIOD OF LIGHT FREEZING RAIN DURING THIS PERIOD. NAM/RUC ISENTROPIC ANALYSES STILL GENERALLY SUPPORTIVE OF PREVIOUS FORECAST IN AREAS OF HIGHEST CHANCE POPS ACROSS THE NORTHERN THIRD OF THE AREA...AND ALSO EXTENDING ACROSS MUCH OF NORTHWEST OHIO THURSDAY MORNING. UPDATED FORECAST WILL BE SENT OVER THE NEXT HOUR TO ADD THIS SLIGHT CHANCE LIGHT FREEZING RAIN MENTION. PREV DISCUSSION... /ISSUED 425 PM EST WED DEC 28 2011/ SHORT TERM... TONIGHT THROUGH THURSDAY NIGHT PAIR OF WEAK CLIPPER SYSTEMS TO IMPACT THE AREA IN THE SHORT TERM. WATER VAPOR IMAGERY AND LATEST RUC ANALYSIS DEPICTING LEAD SHORT WAVE OVER SOUTHERN MANITOBA AND MOVING INTO WESTERN ONTARIO. THIS FEATURE EXPECTED TO WEAKEN/SHEAR OUT IN FAST MOVING NW FLOW PATTERN AS IT DROPS DOWN INTO THE NORTHERN GREAT LAKES TONIGHT/THU AM. RESULT SHOULD BE BETTER CHANCES FOR PRECIP TO REMAIN NORTH OF THE AREA WHERE BETTER FORCING AND MOISTURE WILL BE PRESENT...BUT CLOSE ENOUGH TO MAINTAIN SMALL CHANCE POPS FOR NORTHERN TWO THIRDS OF CWA. MODELS INDICATING DECENT SFC/LOW LEVEL RESPONSE WITH THIS FIRST SHORT WAVE RESULTING IN GOOD WAA IN ADVANCE OF THIS SYSTEM WHICH WILL HAVE TEMPS SLOWLY RISING AFTER MIDNIGHT TONIGHT AND ALSO BRING PRECIP TYPE INTO QUESTION. FCST SOUNDINGS SHOWING DECENT ELEVATED WARM LAYER AND MORE FAVORABLE PROFILES IN SUPPORT OF LIQUID PRECIP...AND WHILE 12Z SOUNDINGS FROM KOAX AND KSGF LEND CREDENCE TO THIS SCENARIO...STILL NOT CONVINCED THAT MUCH LOW LEVEL WARMING WILL BE REALIZED WITH FAST MOVING SYSTEM SO WILL KEEP WITH RA/SN MIX IN WX GRIDS ATTM. 140KT JET COMING ONSHORE IN PACIFIC NW THIS MORNING WILL DRIVE SECOND SHORT WAVE INTO THE AREA QUICKLY BEHIND THE FIRST THURSDAY NIGHT. THIS WAVE WILL DIG FURTHER SOUTH AND BRING BETTER FORCING AND MOISTURE INTO THE FORECAST AREA...AS CURRENTLY REFLECTED IN GRIDS WITH LOW TO HIGH CHANCE POPS FROM EAST TO WEST ACROSS THE CWA. STILL LIKE THE NOTION OF A SMALL WINDOW OF DRY WX BETWEEN THESE TWO SYSTEMS SO WILL STAY WITH DRY FCST 00-06Z FRI. WITH RELATIVELY WARMER AIR IN PLACE...WILL TREND WX GRIDS TOWARD LIQUID PRECIP WITH ALL RAIN IN THE SOUTHERN TIER BUT STAY WITH MIX ELSEWHERE GIVEN NOCTURNAL TIMING. ABOVE NORMAL TEMPS THROUGH THE PERIOD AND GUIDANCE REASONABLE IN HANDLING THIS. LONG TERM... FRIDAY THROUGH WEDNESDAY AN UPPER LEVEL DISTURBANCE WILL TRACK SOUTHEASTWARD FROM SOUTHERN ALBERTA/SASKATCHEWAN THURSDAY MORNING INTO THE MIDWEST BY FRIDAY MORNING. MEDIUM RANGE MODELS ARE IN DECENT AGREEMENT WITH THE TRACK OF THE WAVE AND THE ATTENDANT SURFACE LOW...HOWEVER MINOR TIMING DIFFERENCES EXIST. WENT AHEAD AND BUMPED POPS UP TO LIKELY ACROSS THE NORTHERN HALF OF THE CWA FRIDAY MORNING...ALONG THE PREFERRED TRACK OF THE SURFACE LOW. PRECIPITATION TYPE CONCERNS REMAIN AN ISSUE WITH THIS SYSTEM. THERMAL PROFILES PER MODELS SOUNDINGS SUGGEST MOSTLY RAIN WITH THIS SYSTEM THROUGH THE DAY FRIDAY...WITH COLDER AIR ARRIVING LATE AFTERNOON...INTRODUCING A MIX AND EVENTUAL CHANGEOVER TO SNOW AND PRECIPITATION TAPERS OFF. HOWEVER...GIVEN THE TIMING DIFFERENCES BETWEEN MODELS....AND SLIGHT MODEL DIFFERENCES WITH THE TRACK OF THE SYSTEM...PREFERRED TO LEAVE A RAIN/SNOW MENTION FOR FRIDAY ACROSS THE NORTH AND FRIDAY NIGHT EVERYWHERE. WILL DEFER REFINING OF P-TYPE TO NEXT FORECAST CYCLE AND HOPEFULLY MORE CONSISTENT MODEL SOLUTIONS. NO MAJOR CHANGES TO TEMPERATURES FRIDAY AND FRIDAY NIGHT. SYSTEM EXITS THE REGION BY SATURDAY MORNING...AND HIGH PRESSURE BUILDS INTO THE REGION FROM THE SOUTHWEST. CONDITIONS WILL BE DRY THROUGH THE DAY SATURDAY...BEFORE A SIGNIFICANT PATTERN CHANGE ARRIVES ACROSS THE REGION. UPPER LEVEL TROF WILL DIG SOUTHEAST FROM CANADA INTO THE EASTERN CONUS SUNDAY INTO EARLY NEXT WEEK...AND ALONG WITH IT A POLAR AIR MASS...WITH MODEL H85 TEMPS APPROACHING -20C BY TUESDAY ACROSS THE REGION. SFC LOW PRESSURE WILL MOVE ACROSS THE NORTHERN TIER INTO THE GREAT LAKES REGION BY BY SUNDAY. MODELS DIFFER WITH THE EXACT TRACK OF THE LOW...WITH THE GFS SUPPORTING A FASTER MORE SOUTHERLY TRACK...AND THE ECMWF A BIT SLOWER WITH A MORE NORTHERLY TRACK. CONSEQUENTLY...THE GFS SUPPORTS STRONGER FORCING ACROSS THE REGION SATURDAY NIGHT INTO SUNDAY...WHILE THE ECMWF SUPPORTS WEAKER FORCING MOVING INTO THE AREA DURING THE DAY SUNDAY. ALLBLEND PROCEDURE INTRODUCED SLIGHT CHANCE POPS ON SATURDAY NIGHT...WHICH HAVE BEEN RETAINED FOR COLLABORATIVE PURPOSES. FEEL THAT THE GFS IS SLIGHTLY TO FAST WITH THE TRACK OF THE SYSTEM AND BEST PRECIP CHANCES WILL BE DURING THE DAY SUNDAY. COLD AIR WILL THEN FILTER INTO THE REGION BEHIND THE FRONT...WHICH WILL BE THE CATALYST FOR LAKE EFFECT SNOW LATE SUNDAY THROUGH TUESDAY ACROSS THE AREA. MODELS ARE IN DECENT AGREEMENT OF A NW TO NORTHERLY FETCH AND ADEQUATE MOISTURE PROFILE...WITH LAKE SFC TO H85 DELTA TS IN EXCESS OF 20C...AND LAKE SFC TO H7 DELTA TS IN THE MID TO UPPER 20C RANGE. WENT AHEAD AND RAISED POPS SUNDAY NIGHT INTO TUESDAY TO HIGH CHANCE ACROSS LAKE EFFECT PREFERRED AREAS. NO MAJOR CHANGES TO TEMPERATURES...AS THE ALLBLEND SOLUTIONS HAVE CAUGHT ON TO COLDER TEMPERATURES WITH THE ARRIVAL OF THE POLAR AIR MASS.&& && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 11 PM EST THIS EVENING FOR LMZ043. SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 5 PM EST THIS AFTERNOON FOR LMZ046. && $$ SHORT TERM...LOGSDON LONG TERM...NG UPDATE...MARSILI AVIATION...STEINWEDEL
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
730 PM EST WED DEC 28 2011 .UPDATE... NEXT CLIPPER SYSTEM LOOKS TO IMPACT THE AREA VERY LATE TONIGHT INTO THURSDAY MORNING. STRENGTHENING WESTERLY LOW LEVEL FLOW LATER TONIGHT IN ADVANCE OF THIS FEATURE WILL BEGIN TO ADVECT WARMER LOW LEVEL AIR EASTWARD. POSITIVE LOW LEVEL THEATE ADVECTION ALREADY UNDERWAY ACROSS THE LOCAL AREA EARLY THIS EVENING...ALTHOUGH AIR MASS INITIALLY OVER THE AREA IS QUITE DRY AND MOISTURE AVAILABILITY REMAINS THE PRIMARY LIMITING FACTOR TO PRECIPITATION AMOUNTS WITH THIS CLIPPER. ONLY CHANGE THAT WILL BE MADE TO PREVIOUS FORECAST WILL BE TO ADD SLIGHT CHANCE MENTION OF LIGHT FREEZING RAIN IN THE 11Z TO 15Z TIMEFRAME. DESPITE WARM ADVECTION OVERNIGHT...SHOULD MAINTAIN ENOUGH OF A SHALLOW COLD LAYER TO PROVIDE A BRIEF WINDOW OF SOME LIGHT FREEZING PRECIPITATION. LINGERING SNOWCOVER ACROSS PORTIONS OF THE AREA MAY ALSO AID IN KEEPING LOW LEVEL TEMPS AT OR BELOW FREEZING FOR A LONGER DURATION EARLY THURSDAY MORNING. SOME LOWER CONFIDENCE STILL EXISTS HOWEVER...WITH SOME CONCERNS THAT MOISTURE AVAILABILITY CONCERNS COULD BE MANIFESTED IN PROFILES TOO DRY FOR PRECIP WHILE A THERMODYANAMIC PROFILE SUPPORTIVE OF FREEZING RAIN EXISTS. GIVEN THIS LOWER CONFIDENCE AND EXPECTED LIGHT PRECIP AMOUNTS WILL NOT BE ISSUING ANY HEADLINES BUT WILL LIKELY ISSUE AN SPS ADDRESSING THE CHANCE OF A BRIEF PERIOD OF LIGHT FREEZING RAIN DURING THIS PERIOD. NAM/RUC ISENTROPIC ANALYSES STILL GENERALLY SUPPORTIVE OF PREVIOUS FORECAST IN AREAS OF HIGHEST CHANCE POPS ACROSS THE NORTHERN THIRD OF THE AREA...AND ALSO EXTENDING ACROSS MUCH OF NORTHWEST OHIO THURSDAY MORNING. UPDATED FORECAST WILL BE SENT OVER THE NEXT HOUR TO ADD THIS SLIGHT CHANCE LIGHT FREEZING RAIN MENTION. && .AVIATION... 00Z TAFS...APPROACHING CLIPPER SYSTEM AND PRECIPITATION TYPE CONCERNS FOR THURSDAY MORNING WILL BE THE MAIN FORECAST CONCERN. REGIONAL RADAR MOSAIC INDICATING AN AREA OF PRECIPITATION FROM NORTH CENTRAL NORTH DAKOTA INTO EASTERN SOUTH DAKOTA. A FAST MOVING SHORT WAVE WILL REACH THE WESTERN GREAT LAKES REGION THURSDAY MORNING...EVENTUALLY ALLOWING THIS LIGHT PRECIPITATION TO AFFECT AREAS OF MAINLY FAR NORTHERN INDIANA INTO NORTHWEST OHIO. WARM AIR ADVECTING INTO NORTHERN INDIANA TONIGHT IN ADVANCE OF THIS SYSTEM COUPLED WITH THE POSSIBILITY OF SHALLOW SUBFREEZING AIR AT THE SURFACE DOES LEND SOME CONCERN FOR A VERY BRIEF WINDOW OF LIGHT FREEZING RAIN POTENTIAL SOMETIME IN THE 11Z-15Z TIMEFRAME. HOWEVER...WITH AN INITIALLY VERY DRY AIR MASS CONFIDENCE IS LOW THAT PRECIPITATION WILL OCCUR DURING A TIME WHEN THE THERMAL PROFILES WOULD SUPPORT FREEZING PRECIP. THUS...HAVE KEPT THIS MENTION OUT OF THE TAFS AT THIS TIME AND ADDED A PROB30 -RA MENTION FOR THE MID TO LATE MORNING HOURS AS BOUNDARY LAYER TEMPS WARM ABOVE FREEZING. A FAIRLY STRONG SFC LOW WILL WORK ACROSS CENTRAL LAKE MICHIGAN THURSDAY MORNING...ALLOWING FOR SFC WIND GUSTS TO STRENGTHEN LATE MORNING OR TOWARD MIDDAY WITH GUSTS TO 20 TO 25 KNOTS EXPECTED DURING THE AFTERNOON. DID INCLUDE SOME HIGHER END MVFR CIGS OF DURING THE TIME CORRESPONDING TO THE STRONGEST FORCING IN THE MORNING HOURS. && .PREV DISCUSSION... /ISSUED 425 PM EST WED DEC 28 2011/ SHORT TERM... TONIGHT THROUGH THURSDAY NIGHT PAIR OF WEAK CLIPPER SYSTEMS TO IMPACT THE AREA IN THE SHORT TERM. WATER VAPOR IMAGERY AND LATEST RUC ANALYSIS DEPICTING LEAD SHORT WAVE OVER SOUTHERN MANITOBA AND MOVING INTO WESTERN ONTARIO. THIS FEATURE EXPECTED TO WEAKEN/SHEAR OUT IN FAST MOVING NW FLOW PATTERN AS IT DROPS DOWN INTO THE NORTHERN GREAT LAKES TONIGHT/THU AM. RESULT SHOULD BE BETTER CHANCES FOR PRECIP TO REMAIN NORTH OF THE AREA WHERE BETTER FORCING AND MOISTURE WILL BE PRESENT...BUT CLOSE ENOUGH TO MAINTAIN SMALL CHANCE POPS FOR NORTHERN TWO THIRDS OF CWA. MODELS INDICATING DECENT SFC/LOW LEVEL RESPONSE WITH THIS FIRST SHORT WAVE RESULTING IN GOOD WAA IN ADVANCE OF THIS SYSTEM WHICH WILL HAVE TEMPS SLOWLY RISING AFTER MIDNIGHT TONIGHT AND ALSO BRING PRECIP TYPE INTO QUESTION. FCST SOUNDINGS SHOWING DECENT ELEVATED WARM LAYER AND MORE FAVORABLE PROFILES IN SUPPORT OF LIQUID PRECIP...AND WHILE 12Z SOUNDINGS FROM KOAX AND KSGF LEND CREDENCE TO THIS SCENARIO...STILL NOT CONVINCED THAT MUCH LOW LEVEL WARMING WILL BE REALIZED WITH FAST MOVING SYSTEM SO WILL KEEP WITH RA/SN MIX IN WX GRIDS ATTM. 140KT JET COMING ONSHORE IN PACIFIC NW THIS MORNING WILL DRIVE SECOND SHORT WAVE INTO THE AREA QUICKLY BEHIND THE FIRST THURSDAY NIGHT. THIS WAVE WILL DIG FURTHER SOUTH AND BRING BETTER FORCING AND MOISTURE INTO THE FORECAST AREA...AS CURRENTLY REFLECTED IN GRIDS WITH LOW TO HIGH CHANCE POPS FROM EAST TO WEST ACROSS THE CWA. STILL LIKE THE NOTION OF A SMALL WINDOW OF DRY WX BETWEEN THESE TWO SYSTEMS SO WILL STAY WITH DRY FCST 00-06Z FRI. WITH RELATIVELY WARMER AIR IN PLACE...WILL TREND WX GRIDS TOWARD LIQUID PRECIP WITH ALL RAIN IN THE SOUTHERN TIER BUT STAY WITH MIX ELSEWHERE GIVEN NOCTURNAL TIMING. ABOVE NORMAL TEMPS THROUGH THE PERIOD AND GUIDANCE REASONABLE IN HANDLING THIS. LONG TERM... FRIDAY THROUGH WEDNESDAY AN UPPER LEVEL DISTURBANCE WILL TRACK SOUTHEASTWARD FROM SOUTHERN ALBERTA/SASKATCHEWAN THURSDAY MORNING INTO THE MIDWEST BY FRIDAY MORNING. MEDIUM RANGE MODELS ARE IN DECENT AGREEMENT WITH THE TRACK OF THE WAVE AND THE ATTENDANT SURFACE LOW...HOWEVER MINOR TIMING DIFFERENCES EXIST. WENT AHEAD AND BUMPED POPS UP TO LIKELY ACROSS THE NORTHERN HALF OF THE CWA FRIDAY MORNING...ALONG THE PREFERRED TRACK OF THE SURFACE LOW. PRECIPITATION TYPE CONCERNS REMAIN AN ISSUE WITH THIS SYSTEM. THERMAL PROFILES PER MODELS SOUNDINGS SUGGEST MOSTLY RAIN WITH THIS SYSTEM THROUGH THE DAY FRIDAY...WITH COLDER AIR ARRIVING LATE AFTERNOON...INTRODUCING A MIX AND EVENTUAL CHANGEOVER TO SNOW AND PRECIPITATION TAPERS OFF. HOWEVER...GIVEN THE TIMING DIFFERENCES BETWEEN MODELS....AND SLIGHT MODEL DIFFERENCES WITH THE TRACK OF THE SYSTEM...PREFERRED TO LEAVE A RAIN/SNOW MENTION FOR FRIDAY ACROSS THE NORTH AND FRIDAY NIGHT EVERYWHERE. WILL DEFER REFINING OF P-TYPE TO NEXT FORECAST CYCLE AND HOPEFULLY MORE CONSISTENT MODEL SOLUTIONS. NO MAJOR CHANGES TO TEMPERATURES FRIDAY AND FRIDAY NIGHT. SYSTEM EXITS THE REGION BY SATURDAY MORNING...AND HIGH PRESSURE BUILDS INTO THE REGION FROM THE SOUTHWEST. CONDITIONS WILL BE DRY THROUGH THE DAY SATURDAY...BEFORE A SIGNIFICANT PATTERN CHANGE ARRIVES ACROSS THE REGION. UPPER LEVEL TROF WILL DIG SOUTHEAST FROM CANADA INTO THE EASTERN CONUS SUNDAY INTO EARLY NEXT WEEK...AND ALONG WITH IT A POLAR AIR MASS...WITH MODEL H85 TEMPS APPROACHING -20C BY TUESDAY ACROSS THE REGION. SFC LOW PRESSURE WILL MOVE ACROSS THE NORTHERN TIER INTO THE GREAT LAKES REGION BY BY SUNDAY. MODELS DIFFER WITH THE EXACT TRACK OF THE LOW...WITH THE GFS SUPPORTING A FASTER MORE SOUTHERLY TRACK...AND THE ECMWF A BIT SLOWER WITH A MORE NORTHERLY TRACK. CONSEQUENTLY...THE GFS SUPPORTS STRONGER FORCING ACROSS THE REGION SATURDAY NIGHT INTO SUNDAY...WHILE THE ECMWF SUPPORTS WEAKER FORCING MOVING INTO THE AREA DURING THE DAY SUNDAY. ALLBLEND PROCEDURE INTRODUCED SLIGHT CHANCE POPS ON SATURDAY NIGHT...WHICH HAVE BEEN RETAINED FOR COLLABORATIVE PURPOSES. FEEL THAT THE GFS IS SLIGHTLY TO FAST WITH THE TRACK OF THE SYSTEM AND BEST PRECIP CHANCES WILL BE DURING THE DAY SUNDAY. COLD AIR WILL THEN FILTER INTO THE REGION BEHIND THE FRONT...WHICH WILL BE THE CATALYST FOR LAKE EFFECT SNOW LATE SUNDAY THROUGH TUESDAY ACROSS THE AREA. MODELS ARE IN DECENT AGREEMENT OF A NW TO NORTHERLY FETCH AND ADEQUATE MOISTURE PROFILE...WITH LAKE SFC TO H85 DELTA TS IN EXCESS OF 20C...AND LAKE SFC TO H7 DELTA TS IN THE MID TO UPPER 20C RANGE. WENT AHEAD AND RAISED POPS SUNDAY NIGHT INTO TUESDAY TO HIGH CHANCE ACROSS LAKE EFFECT PREFERRED AREAS. NO MAJOR CHANGES TO TEMPERATURES...AS THE ALLBLEND SOLUTIONS HAVE CAUGHT ON TO COLDER TEMPERATURES WITH THE ARRIVAL OF THE POLAR AIR MASS.&& && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...LOGSDON LONG TERM...NG AVIATION...MARSILI UPDATE...MARSILI
AREA FORECAST DISCUSSION
NWS GOODLAND KS
219 AM MST THU DEC 29 2011 .SHORT TERM (TODAY-SATURDAY)... 218 AM MST THU DEC 29 2011 WINDS AND TEMPERATURES ARE THE CHALLENGES WITH THE SHORT TERM PART OF THE FORECAST. FAST MOVING SHORT WAVE TROUGH WILL MOVE ACROSS THE NEBRASKA PANHANDLE AFTER 18Z TODAY. ONLY EXPECT TO SEE INCREASING CIRRUS CLOUDS WITH THE FEATURE AS BEST DIFFERENTIAL CYCLONIC VORTICITY ADVECTION WILL BE NORTH OF AREA. 850 MB ANALYSIS SHOWED 8 DEGREE CELSIUS TEMPERATURES FROM KDDC TO KLBF...AND MOST MODELS AGREE THAT TEMPERATURES WILL REACH 12-14 DEGREES CELSIUS BY THIS AFTERNOON. THIS WILL PRODUCE TEMPERATURES IN THE LOW TO MID 60S...EXCEPT AREAS SOUTH OF INTERSTATE 70 THAT ARE STILL IMPACTED BY SNOW COVER. MAY NOT HAVE THE BENEFIT OF FULL SOLAR INSOLATION GIVEN INCREASING HIGH LEVEL CLOUDS..BY HIGHS TODAY COULD BE CLOSE TO RECORDS. THE RECORD HIGH AT KITR IS 63 WHICH IS WITHIN REACH. WINDS TODAY ARE PROBLEMATIC. THERE IS DECENT POTENTIAL FOR MIXING...AND 850 MB WINDS WILL BE 30-40 KNOTS. SURFACE GRADIENT IS NOT IMPRESSIVE...HOWEVER... AND WILL ONLY MENTION BREEZY CONDITIONS TODAY THOUGH THE NEBRASKA COUNTIES MAY HAVE HIGHER GUSTS WHERE 850 MB WINDS WILL BE THE STRONGEST. FIRST SHORT WAVE MOVES EAST TONIGHT...BUT PUSHES COOLER AIR ACROSS THE FORECAST AREA. TEMPERATURES FRIDAY WILL BE 5-10 DEGREES COOLER. NEXT SHORTWAVE TROUGH MOVES OVER THE NORTHERN ROCKIES FRIDAY NIGHT. IT WILL BE STRONGER AND FURTHER SOUTH THAN THE PRIOR FEATURE...BUT MOISTURE WILL CONTINUE TO BE LIMITED THIS FAR SOUTH. AN ASSOCIATED COLD FRONT WILL MOVE THROUGH THE AREA SATURDAY. TIMING IS STILL UNCERTAIN...BUT 18Z SATURDAY AFTERNOON IS A LOGICAL STARTING POINT FOR FRONTAL PASSAGE AT KGLD. HOWEVER...DEPENDING ON THE TIMING... TEMPERATURES MAY WARM INTO THE MID 50S...OR NOT EVEN REACH THE 50S. HAVE TRENDED TEMPERATURES DOWN FOR SATURDAY AFTERNOON...BUT SUBSEQUENT MODEL RUNS WILL PROVIDE A CLEARER PICTURE ABOUT TEMPERATURES. IT SEEMS A GIVEN...HOWEVER...THAT WINDS BEHIND THE FRONT WILL BE STRONG. HAVE REALLY BOOSTED THE FORECASTED WINDS SATURDAY AFTERNOON...AND WOULD NOT BE SURPRISED TO SEE A WIND HIGHLIGHT EVENTUALLY BE ISSUED. && .LONG TERM (SUNDAY-WEDNESDAY)... 218 AM MST THU DEC 29 2011 SUNDAY THROUGH WEDNESDAY...DID NOT MAKE ANY CHANGES FROM INITIALIZED GRIDS SINCE THEY LOOK REASONABLE AT THIS TIME. HOWEVER... DETERMINISTIC AND ENSEMBLE MODEL OUTPUT ARE NOT IN VERY GOOD AGREEMENT WITH THE MID/UPPER PATTERN...MAINLY FOR THE SUNDAY INTO TUESDAY TIME PERIOD. ONE THING FOR SURE...NO MATTER WHICH MODEL ONE USES THE PATTERN IS A DRY ONE...AND GRIDS REFLECT THAT. WHERE THE DIFFERENCES ALOFT CAUSE PROBLEMS IS WITH THE SURFACE WIND AND TEMPERATURE FORECASTS. ON SUNDAY TEMPERATURES WILL BE COOLER THAN SATURDAY DUE TO A COLD FRONT MOVING THROUGH ON SATURDAY. HOWEVER...DIFFERENCES IN HOW COLD THE MODELS MAKE IT SHOW UP. CANADIAN IS MUCH COLDER...THE GFS THE WARMEST AND THE ECMWF SLIGHTLY COLDER THAN THE GFS. DUE TO MODEL DIFFERENCES AND SNOW FIELD...LEFT CURRENT MAXES ALONE BUT POTENTIAL IS THERE FOR IT TO BE COOLER. ON MONDAY...RETURN FLOW BEGINS AND WOULD EXPECT SOME WARMING. HOWEVER THIS FLOW IS COMING OVER SUBSTANTIAL SNOWFIELD TO OUR SOUTH AND SURFACE HIGH IS NOT THAT FAR AWAY. POTENTIAL IS THERE FOR IT BEING COOLER THAN WHAT IS IN THERE. DEPENDING ON WHICH MODEL YOU CHOOSE...THERE LOOKS TO BE ANOTHER COOL SURGE MOVING THROUGH TUESDAY INTO TUESDAY NIGHT WHICH COULD CAUSE THE HIGH TEMPERATURES TO BE COOLER THAN THE RATHER MILD/ABOVE NORMAL TEMPERATURES THAT ARE IN THERE FOR TUESDAY AND WEDNESDAY. ALSO HOW MUCH OF THE SNOW FIELD REMAINS WILL ALSO BE A FACTOR IN THE WARM UP. && .AVIATION... 1020 PM MST WED DEC 28 2011 FOR THE 06Z TAFS AT KGLD AND KMCK...VFR THROUGH THE PERIOD. WEST WINDS OF 10-15KTS EXPECTED THROUGH 18Z THEN INCREASING SLIGHTLY WITH GUSTS 25KTS OR SO AS A SFC TROUGH MOVES THROUGH. STILL SOME UNCERTAINTY AS TO WHETHER THE STRONGER WINDS ALOFT MIX DOWN AS LATEST RUC MODEL SHOWING SUSTAINED WINDS AT KGLD AROUND 20-25KTS WITH HIGHER GUSTS BY 20Z. BY 00Z WINDS BACK OFF WITH SPEEDS 10-15KTS. CLOUDINESS WILL BE LIMITED TO MID AND UPPER LEVELS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1020 PM MST WED DEC 28 2011 .DISCUSSION... 224 PM MST WED DEC 28 2011 A SERIES OF SHORT WAVE TROUGHS ALOFT...AND THEIR ACCOMPANYING SURFACE SYSTEMS...ARE FORECAST TO MOVE RAPIDLY SOUTHEAST ACROSS THE NORTHERN PLAINS THROUGH FRIDAY. PRECIPITATION POTENTIAL FOR US LOOKS SLIM WITH THESE SYSTEMS GIVEN THEIR LOCATION...SPEED AND AN OVERALL LACK OF LOW TO MID LEVEL MOISTURE. HOWEVER...THEY WILL BRING A FLUCTUATION IN SURFACE TEMPERATURES OVER THE NEXT FEW DAYS. 850 MB TEMPERATURES ARE FORECAST TO CLIMB 3-5 DEGREES C THURSDAY OVER TODAYS TEMPS DEPENDING ON WHICH MODEL IS VIEWED. GIVEN CURRENT TEMPERATURES IN THE MIDDLE 50S IN THE SNOW-FREE AREAS...LOWER 60S SEEM A GOOD BET FOR TOMORROWS HIGHS. TEMPERATURES WILL COOL TO THE 40S AND 50S FRIDAY AS SURFACE WINDS SHIFT BACK TO NORTHWEST AND 850 TEMPS COOL. THE SNOW COVERED AREAS STILL PRESENT A CHALLENGE FOR TEMPERATURE FORECASTING... REMAINING SOME 15 DEGREES COLDER THAN BARE GROUND. WILL CONTINUE THIS COOLER TREND OVER THE SNOW FOR THE NEXT FEW DAYS BUT WITH DIMINISHING IMPACT AS SNOW COVER DECREASES. THE STRENGTH OF SURFACE WINDS THURSDAY ARE STILL A BIT UNCERTAIN. GUIDANCE DIFFERS WITH FORECAST 850 MB WINDS TOMORROW...WITH THE ECMWF SHOWING SPEEDS OF 15-20 KTS WHILE THE GFS SHOWS 35-40 KTS ACROSS THE NORTH. FOR NOW HAVE PLACED STRONGEST WINDS IN THE NORTH THIRD WITH GUSTS TO AROUND 30 MPH BUT THIS MAY NEED TO BE REVISITED. THE NEXT SIGNIFICANT SYSTEM TO IMPACT THE REGION WILL BE IN THE SATURDAY-SUNDAY TIME FRAME AS A PROGRESSIVE TROUGH DIGS SOUTHEAST FROM THE PACIFIC NORTHWEST. GUIDANCE HAS BEEN HIT AND MISS FOR SPOTTY PRECIPITATION WITH THAT SYSTEM. GIVEN SURFACE HIGH PRESSURE ACROSS THE TX-OK AREA AHEAD OF THIS TROUGH...MOISTURE WILL AGAIN BE SPARSE DOWN LOW. ALTHOUGH SOME SPOTTY PRECIP CANT BE RULED OUT...WILL CONTINUE THE DRY FORECAST. THE LONGER RANGE GUIDANCE INDICATES UPPER RIDGING WILL RETURN EARLY NEXT WEEK...CONTINUING THE MILD AND DRY TREND AS WE KICK OFF THE NEW YEAR. 99 && .AVIATION... 1020 PM MST WED DEC 28 2011 FOR THE 06Z TAFS AT KGLD AND KMCK...VFR THROUGH THE PERIOD. WEST WINDS OF 10-15KTS EXPECTED THROUGH 18Z THEN INCREASING SLIGHTLY WITH GUSTS 25KTS OR SO AS A SFC TROUGH MOVES THROUGH. STILL SOME UNCERTAINTY AS TO WHETHER THE STRONGER WINDS ALOFT MIX DOWN AS LATEST RUC MODEL SHOWING SUSTAINED WINDS AT KGLD AROUND 20-25KTS WITH HIGHER GUSTS BY 20Z. BY 00Z WINDS BACK OFF WITH SPEEDS 10-15KTS. CLOUDINESS WILL BE LIMITED TO MID AND UPPER LEVELS. 007 && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1036 AM MST TUE DEC 27 2011 .UPDATE... 1034 AM MST TUE DEC 27 2011 UPDATED TODAY/S HIGH TEMPS BY RAISING MOST AREAS UPWARD BY A CATEGORY BASED ON LATEST TRENDS IN THE SFC OBS. NO OTHER CHANGES WERE NEEDED. 05 && .SYNOPSIS... CURRENT SATELLITE IMAGERY AND RUC UPPER AIR ANALYSIS SHOW A HIGH PRESSURE OVER THE SOUTHWEST CONUS...WITH A SHORT WAVE TROUGH AND MID LEVEL MOISTURE MOVING AROUND THE NORTHERN PERIPHERY OF THE HIGH ALONG THE US/CANADIAN BORDER. OVER THE CENTRAL PLAINS A SHORT WAVE TROUGH IN THE NORTHWEST FLOW WAS PRODUCING A FEW CLOUDS. CLOSER TO HOME A SURFACE HIGH PRESSURE WAS BUILDING INTO THE TRI-STATE AREA. LATEST REPORTS OF SNOW DEPTH SHOW 2 TO 10 INCHES STILL ON THE GROUND FOR AREAS OF CENTRAL AND SOUTHWEST KANSAS...SO AM EXPECTING THIS TO HAVE A COOLING EFFECT ON TEMPERATURES THROUGH THE PERIOD. JTL && .SHORT TERM (TODAY-THURSDAY)... 228 AM MST TUE DEC 27 2011 TEMPERATURES WILL BE THE MAIN CONCERN FOR THIS PERIOD. SURFACE HIGH PRESSURE WILL MOVE ACROSS THE TRI-STATE AREA TODAY...PRECEDING A SURFACE AND UPPER LEVEL TROUGH THAT WILL MOVE THROUGH DURING THE EVENING HOURS. MODELS HAVE REDUCED THE AMOUNT OF MOISTURE AND LIFT WITH THE TROUGH PASSAGE...SO WILL FOLLOW PREVIOUS SHIFT AND KEEP OUT ANY MENTION OF PRECIPITATION. HIGH TEMPERATURES A BIT TRICKY DUE TO THE COMBINED EFFECTS OF CLOUD COVER AND SOUTHERLY WINDS BRINGING IN COOLER AIR FROM THE SNOW FIELD...BUT OVERALL TEMPERATURES TODAY WILL BE COOLER THAN YESTERDAY. LOWS TONIGHT WILL BE A FEW DEGREES WARMER THAN LAST NIGHT. WEDNESDAY MINOR RIPPLES WILL MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA...PRODUCING A FEW CLOUDS AT BEST. WITH WESTERLY WINDS BRINGING IN WARMER AIR...TEMPERATURES WILL BE WARMER THAN TUESDAY. THURSDAY A MINOR SHORT WAVE TROUGH AND SOME MOISTURE MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA. THIS TROUGH WILL HAVE MORE LIFT WITH IT...BUT WILL HAVE THE BEST LIFT BELOW THE MOISTURE. AS SUCH WILL LEAVE OUT A MENTION OF ANY PRECIPITATION AS THE TROUGH MOVES THROUGH. AT THE SURFACE WINDS WILL BECOME NORTHWEST BEHIND THE TROUGH AND STRENGTHEN SOME...WITH THE STRONGER WINDS OVER THE NEBRASKA COUNTIES. TEMPERATURES WILL CONTINUE THE WARMING TREND. 850MB TEMPERATURES WARM TO NEAR 10C DURING THE DAY...SO WENT WITH THE WARMER GUIDANCE SINCE 850MB TEMPERATURES OF 3C YESTERDAY AND NORTHWEST WINDS PRODUCED HIGHS AROUND 50 DEGREES...SO HIGHS AROUND 60 ARE NOT OUT OF THE QUESTION. JTL .LONG TERM (FRIDAY-MONDAY)... 228 AM MST TUE DEC 27 2011 LONG RANGE MODELS CONTINUE TO SHOW WEAK SHORT WAVE TROUGHS MOVING ACROSS THE HIGH PLAINS IN PSEUDO ZONAL FLOW THROUGH THE WEEKEND. THE STRONGEST WAVE IS DUE SATURDAY AFTERNOON OR SATURDAY NIGHT DEPENDING ON MODEL PREFERENCE...BUT MOISTURE APPEARS LIMITED REGARDLESS SO WILL KEEP FORECASTS DRY. WARM AIR ADVECTION AND ABOVE NORMAL 500 MB HEIGHTS SUPPORT DECENT WARM/UP BETWEEN THE SHORT WAVES...ESPECIALLY FRIDAY WHEN 850 MB TEMPERATURES ARE PROGGED TO REACH BETWEEN 12-14 DEGREES CELSIUS. AGREE WITH SURROUNDING OFFICES TO INCREASE MAXIMUM TEMPERATURE FORECASTS THAT DAY. EVEN WITH WARM AIR ADVECTION...TEMPERATURES SOUTH OF INTERSTATE 70 WILL BE DEPENDENT ON THE AMOUNT OF SNOW PACK MELTING THAT OCCURS BETWEEN NOW AND FRIDAY. EXPECT ENOUGH MELTING TO ALLOW TEMPERATURES TO FINALLY REACH INTO THE 50S THERE BY FRIDAY. && .AVIATION... 1018 AM MST TUE DEC 27 2011 FOR THE 18Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. LIGHT WINDS HAVE BACKED TO THE SOUTHWEST AS LOW PRESSURE DEEPENED TO THE NORTHEAST OF THE TERMINALS. WINDS WILL RETURN TO THE NORTHWEST OVERNIGHT AS HIGH PRESSURE BUILDS ACROSS THE REGION. CJS && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1018 AM MST TUE DEC 27 2011 .SYNOPSIS... CURRENT SATELLITE IMAGERY AND RUC UPPER AIR ANALYSIS SHOW A HIGH PRESSURE OVER THE SOUTHWEST CONUS...WITH A SHORT WAVE TROUGH AND MID LEVEL MOISTURE MOVING AROUND THE NORTHERN PERIPHERY OF THE HIGH ALONG THE US/CANADIAN BORDER. OVER THE CENTRAL PLAINS A SHORT WAVE TROUGH IN THE NORTHWEST FLOW WAS PRODUCING A FEW CLOUDS. CLOSER TO HOME A SURFACE HIGH PRESSURE WAS BUILDING INTO THE TRI-STATE AREA. LATEST REPORTS OF SNOW DEPTH SHOW 2 TO 10 INCHES STILL ON THE GROUND FOR AREAS OF CENTRAL AND SOUTHWEST KANSAS...SO AM EXPECTING THIS TO HAVE A COOLING EFFECT ON TEMPERATURES THROUGH THE PERIOD. JTL && .SHORT TERM (TODAY-THURSDAY)... 228 AM MST TUE DEC 27 2011 TEMPERATURES WILL BE THE MAIN CONCERN FOR THIS PERIOD. SURFACE HIGH PRESSURE WILL MOVE ACROSS THE TRI-STATE AREA TODAY...PRECEDING A SURFACE AND UPPER LEVEL TROUGH THAT WILL MOVE THROUGH DURING THE EVENING HOURS. MODELS HAVE REDUCED THE AMOUNT OF MOISTURE AND LIFT WITH THE TROUGH PASSAGE...SO WILL FOLLOW PREVIOUS SHIFT AND KEEP OUT ANY MENTION OF PRECIPITATION. HIGH TEMPERATURES A BIT TRICKY DUE TO THE COMBINED EFFECTS OF CLOUD COVER AND SOUTHERLY WINDS BRINGING IN COOLER AIR FROM THE SNOW FIELD...BUT OVERALL TEMPERATURES TODAY WILL BE COOLER THAN YESTERDAY. LOWS TONIGHT WILL BE A FEW DEGREES WARMER THAN LAST NIGHT. WEDNESDAY MINOR RIPPLES WILL MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA...PRODUCING A FEW CLOUDS AT BEST. WITH WESTERLY WINDS BRINGING IN WARMER AIR...TEMPERATURES WILL BE WARMER THAN TUESDAY. THURSDAY A MINOR SHORT WAVE TROUGH AND SOME MOISTURE MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA. THIS TROUGH WILL HAVE MORE LIFT WITH IT...BUT WILL HAVE THE BEST LIFT BELOW THE MOISTURE. AS SUCH WILL LEAVE OUT A MENTION OF ANY PRECIPITATION AS THE TROUGH MOVES THROUGH. AT THE SURFACE WINDS WILL BECOME NORTHWEST BEHIND THE TROUGH AND STRENGTHEN SOME...WITH THE STRONGER WINDS OVER THE NEBRASKA COUNTIES. TEMPERATURES WILL CONTINUE THE WARMING TREND. 850MB TEMPERATURES WARM TO NEAR 10C DURING THE DAY...SO WENT WITH THE WARMER GUIDANCE SINCE 850MB TEMPERATURES OF 3C YESTERDAY AND NORTHWEST WINDS PRODUCED HIGHS AROUND 50 DEGREES...SO HIGHS AROUND 60 ARE NOT OUT OF THE QUESTION. JTL .LONG TERM (FRIDAY-MONDAY)... 228 AM MST TUE DEC 27 2011 LONG RANGE MODELS CONTINUE TO SHOW WEAK SHORT WAVE TROUGHS MOVING ACROSS THE HIGH PLAINS IN PSEUDO ZONAL FLOW THROUGH THE WEEKEND. THE STRONGEST WAVE IS DUE SATURDAY AFTERNOON OR SATURDAY NIGHT DEPENDING ON MODEL PREFERENCE...BUT MOISTURE APPEARS LIMITED REGARDLESS SO WILL KEEP FORECASTS DRY. WARM AIR ADVECTION AND ABOVE NORMAL 500 MB HEIGHTS SUPPORT DECENT WARM/UP BETWEEN THE SHORT WAVES...ESPECIALLY FRIDAY WHEN 850 MB TEMPERATURES ARE PROGGED TO REACH BETWEEN 12-14 DEGREES CELSIUS. AGREE WITH SURROUNDING OFFICES TO INCREASE MAXIMUM TEMPERATURE FORECASTS THAT DAY. EVEN WITH WARM AIR ADVECTION...TEMPERATURES SOUTH OF INTERSTATE 70 WILL BE DEPENDENT ON THE AMOUNT OF SNOW PACK MELTING THAT OCCURS BETWEEN NOW AND FRIDAY. EXPECT ENOUGH MELTING TO ALLOW TEMPERATURES TO FINALLY REACH INTO THE 50S THERE BY FRIDAY. && .AVIATION... 1018 AM MST TUE DEC 27 2011 FOR THE 18Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. LIGHT WINDS HAVE BACKED TO THE SOUTHWEST AS LOW PRESSURE DEEPENED TO THE NORTHEAST OF THE TERMINALS. WINDS WILL RETURN TO THE NORTHWEST OVERNIGHT AS HIGH PRESSURE BUILDS ACROSS THE REGION. CJS && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
413 AM MST TUE DEC 27 2011 .SYNOPSIS... CURRENT SATELLITE IMAGERY AND RUC UPPER AIR ANALYSIS SHOW A HIGH PRESSURE OVER THE SOUTHWEST CONUS...WITH A SHORT WAVE TROUGH AND MID LEVEL MOISTURE MOVING AROUND THE NORTHERN PERIPHERY OF THE HIGH ALONG THE US/CANADIAN BORDER. OVER THE CENTRAL PLAINS A SHORT WAVE TROUGH IN THE NORTHWEST FLOW WAS PRODUCING A FEW CLOUDS. CLOSER TO HOME A SURFACE HIGH PRESSURE WAS BUILDING INTO THE TRI-STATE AREA. LATEST REPORTS OF SNOW DEPTH SHOW 2 TO 10 INCHES STILL ON THE GROUND FOR AREAS OF CENTRAL AND SOUTHWEST KANSAS...SO AM EXPECTING THIS TO HAVE A COOLING EFFECT ON TEMPERATURES THROUGH THE PERIOD. JTL && .SHORT TERM (TODAY-THURSDAY)... 228 AM MST TUE DEC 27 2011 TEMPERATURES WILL BE THE MAIN CONCERN FOR THIS PERIOD. SURFACE HIGH PRESSURE WILL MOVE ACROSS THE TRI-STATE AREA TODAY...PRECEDING A SURFACE AND UPPER LEVEL TROUGH THAT WILL MOVE THROUGH DURING THE EVENING HOURS. MODELS HAVE REDUCED THE AMOUNT OF MOISTURE AND LIFT WITH THE TROUGH PASSAGE...SO WILL FOLLOW PREVIOUS SHIFT AND KEEP OUT ANY MENTION OF PRECIPITATION. HIGH TEMPERATURES A BIT TRICKY DUE TO THE COMBINED EFFECTS OF CLOUD COVER AND SOUTHERLY WINDS BRINGING IN COOLER AIR FROM THE SNOW FIELD...BUT OVERALL TEMPERATURES TODAY WILL BE COOLER THAN YESTERDAY. LOWS TONIGHT WILL BE A FEW DEGREES WARMER THAN LAST NIGHT. WEDNESDAY MINOR RIPPLES WILL MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA...PRODUCING A FEW CLOUDS AT BEST. WITH WESTERLY WINDS BRINGING IN WARMER AIR...TEMPERATURES WILL BE WARMER THAN TUESDAY. THURSDAY A MINOR SHORT WAVE TROUGH AND SOME MOISTURE MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA. THIS TROUGH WILL HAVE MORE LIFT WITH IT...BUT WILL HAVE THE BEST LIFT BELOW THE MOISTURE. AS SUCH WILL LEAVE OUT A MENTION OF ANY PRECIPITATION AS THE TROUGH MOVES THROUGH. AT THE SURFACE WINDS WILL BECOME NORTHWEST BEHIND THE TROUGH AND STRENGTHEN SOME...WITH THE STRONGER WINDS OVER THE NEBRASKA COUNTIES. TEMPERATURES WILL CONTINUE THE WARMING TREND. 850MB TEMPERATURES WARM TO NEAR 10C DURING THE DAY...SO WENT WITH THE WARMER GUIDANCE SINCE 850MB TEMPERATURES OF 3C YESTERDAY AND NORTHWEST WINDS PRODUCED HIGHS AROUND 50 DEGREES...SO HIGHS AROUND 60 ARE NOT OUT OF THE QUESTION. JTL .LONG TERM (FRIDAY-MONDAY)... 228 AM MST TUE DEC 27 2011 LONG RANGE MODELS CONTINUE TO SHOW WEAK SHORT WAVE TROUGHS MOVING ACROSS THE HIGH PLAINS IN PSEUDO ZONAL FLOW THROUGH THE WEEKEND. THE STRONGEST WAVE IS DUE SATURDAY AFTERNOON OR SATURDAY NIGHT DEPENDING ON MODEL PREFERENCE...BUT MOISTURE APPEARS LIMITED REGARDLESS SO WILL KEEP FORECASTS DRY. WARM AIR ADVECTION AND ABOVE NORMAL 500 MB HEIGHTS SUPPORT DECENT WARM/UP BETWEEN THE SHORT WAVES...ESPECIALLY FRIDAY WHEN 850 MB TEMPERATURES ARE PROGGED TO REACH BETWEEN 12-14 DEGREES CELSIUS. AGREE WITH SURROUNDING OFFICES TO INCREASE MAXIMUM TEMPERATURE FORECASTS THAT DAY. EVEN WITH WARM AIR ADVECTION...TEMPERATURES SOUTH OF INTERSTATE 70 WILL BE DEPENDENT ON THE AMOUNT OF SNOW PACK MELTING THAT OCCURS BETWEEN NOW AND FRIDAY. EXPECT ENOUGH MELTING TO ALLOW TEMPERATURES TO FINALLY REACH INTO THE 50S THERE BY FRIDAY. && .AVIATION... 413 AM MST TUE DEC 27 2011 VFR CONDITIONS WILL CONTINUE THROUGH THE FORECAST PERIOD AT KGLD/KMCK. SURFACE WINDS AT 10-15 KNOTS WILL GRADUALLY BECOME SOUTHWEST TODAY BEFORE RETURNING TO THE NORTHWEST AFTER 00Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS...

/TODAY THROUGH WEDNESDAY NIGHT/ MODELS ARE IN GOOD AGREEMENT FOR THE PERIOD. A MID/UPPER LEVEL LOW CROSSING THE LOWER MISSISSIPPI VALLEY ON MONDAY NIGHT WAS BEING ABSORBED BACK INTO THE PREVAILING WESTERLIES AS A NORTHERN STREAM TROUGH DROPPED SE TOWARD THE GREAT LAKES. THIS IS RESULTING IN A DEEPENING SURFACE LOW OVER WEST TN WHICH WILL MOVE NE ACROSS KY. THE SYSTEM HAS A DEEP MOISTURE TAP...WITH RAIN HAVING OVERSPREAD THE AREA DURING THE NIGHT. A DRY SLOT WRAPPING NORTHWARD INTO THE SYSTEM WILL TRY TO MOVE N INTO KY TODAY...BRINGING A DIMINISHING TREND IN RAIN... ESPECIALLY FOR OUR SOUTHERN AND SOUTHEASTERN COUNTIES LATE THIS MORNING AND EARLY THIS AFTERNOON. THE TAIL OF THE COMMA HEAD WILL MOVE EAST ACROSS THE AREA THIS AFTERNOON. IT WILL BRING ANOTHER INCREASE IN PRECIP...ESPECIALLY FOR OUR NORTHERN AND EASTERN COUNTIES. THIS PRECIP WILL BE MUCH LIGHTER THAN THAT OF THE MORNING. WITH COLDER AIR ARRIVING ON THE BACK SIDE OF THE SURFACE LOW...THE RAIN WILL MIX WITH OR CHANGE TO SNOW FROM NW TO SE DURING THE LATE AFTERNOON AND EVENING. COLDER AIR ALOFT WILL SUPPORT A SURFACE CHANGEOVER TEMPERATURE IN THE MID 30S. WILL EXPECT PRECIP TO TAPER OFF BEFORE TEMPS FALL BELOW FREEZING IN MOST LOCATIONS...PREVENTING SIGNIFICANT SNOW ACCUMULATIONS. A POSSIBLE EXCEPTION WILL BE ELEVATIONS ABOVE ABOUT 2000 FEET NEAR THE VA BORDER...AND WILL CALL FOR A POSSIBILITY OF 1-2 INCHES THERE TONIGHT. MUCH DRIER AIR SHOULD ARRIVE BY WEDNESDAY MORNING...WITH DRY WEATHER AND MAINLY CLEAR SKIES FORECAST FOR WEDNESDAY AND WEDNESDAY NIGHT. HIGH PRESSURE WILL BUILD IN FROM THE WEST ON WEDNESDAY...WITH THE RIDGE MOVING TO OUR EAST ON WEDNESDAY NIGHT. THE RETURN OF WARM AIR ADVECTION ON THE BACK SIDE OF THE HIGH ON WEDNESDAY NIGHT WILL PROMOTE RIDGE/VALLEY LOW TEMPERATURE DIFFERENCES. .LONG TERM.../THURSDAY THROUGH MONDAY/ THE EXTENDED FORECAST BEGINS ON THURSDAY WITH A PROGRESSIVE PATTERN IN PLACE AND A BROAD TROUGH OVER THE EASTERN US. THE MAIN CONCERN COMES IN THE FRIDAY TO SATURDAY PERIOD IN THE FORM OF A COUPLE OF ALBERTA CLIPPER TYPE LOWS IN NORTHWEST FLOW. BOTH THE GFS AND EURO ARE AGREEING WITH THE STRENGTH AND POSITIONING OF THE DISTURBANCE BUT ARE DIVIDED ON THE TIMING. QPF WITH THIS SYSTEM IS MINIMAL AT BEST...ESPECIALLY WITH ITS CONTINENTAL ORIGIN. AT THIS POINT...SNOW SEEMS A BIT FAR FETCHED AS BOTH THE EURO AND GFS DO NOT SHOW ANY SIGNIFICANT COLD AIR IN PLACE AND EVEN ON THE BACK SIDE OF THE SYSTEM. THEREFORE...WILL LIKELY THROW IN AT LEAST SOME SLIGHT CHANCE POPS ON FRIDAY AND INTO SATURDAY. THE ONLY OTHER CONCERN IS A STRONGER WAVE DEVELOPING AND MOVING THROUGH SUNDAY NIGHT AND INTO MONDAY. THE DIFFERENCES WITH THE EURO AND GFS WITH THIS IS TIMING AS THE GFS IS 24 HOURS FASTER AND WEAKER THAN THE EURO WITH A SLOWER AND MORE AMPLIFIED PATTERN. THE EURO DEVELOPS A SHARP TROUGH DIGGING FROM THE GREAT LAKES TO THE GULF COAST...ALLOWING BITTERLY COLD AIR INTO THE EAST COAST. FOR NOW THE GFS AND GEM STICK TO THE GFS ENSEMBLE. WILL STICK TO THE FAST GFS SOLUTION...ESPECIALLY WITH THE PROGRESSIVE PATTERN IN PLACE DURING THE BEGINNING OF THE EXTENDED. AFTER INITIALIZATION AND THE 00Z EURO STICKING TO A SLOWER AMPLIFIED PATTERN FOR THE MON TO TUE TIME FRAME. THE INITIALIZATION DID LEAN TO THE EURO A BIT BUT THIS IS THE 12Z RUN. WITH THE EURO SHOWING SOME RUN TO RUN CONSISTENCY WITH THIS AND DEVELOPING A VIGOROUS COASTAL LOW ON THE MON THROUGH WED TIME FRAME...WILL HAVE TO WATCH TO SEE IF THE OTHER OPERATIONAL MODELS SHIFT TO THIS SOLUTION. THE OTHER PIECE OF INFORMATION IS WHAT THE NAO IS SHOWING AND WHILE ITS ENSEMBLE MEMBERS DO SHOW SOME DIFFERENT SOLUTIONS...A INDICATION OF A MORE PROGRESSIVE PATTERN AND LESS BLOCKING IS SHOWN THROUGH JAN 1ST...SOME OF THE MEMBERS DO DIP INTO THE NEGATIVE RANGE BY THE 3RD INDICATING A MORE AMPLIFIED PATTERN. THEREFORE...FOR THE FORECAST WILL CLEAR OUT POPS BY MONDAY ACCORDING TO THE GFS SOLUTION BUT THE EURO SOLUTION AS WELL AS THE ENSEMBLES WILL NEED SOME MONITORING. && .AVIATION.../18Z TO 18Z/...UPDATED SOUTHWEST WINDS WILL BRIEFLY GUST TO 30 TO 35 KNOTS THIS AFTERNOON. SURFACE LOW PRESSURE HAS MOVED INTO WESTERN OH. A LOW PRESSURE TROF SWINGING NORTHEAST THROUGH THE AREA IS BRINGING WIDESPREAD RAIN AND MVFR TO IFR CONDITIONS. GUSTY WINDS ARE OCCURRING IN A SMALL PRECIPITATION FREE AREA BETWEEN THE PRIMARY RAIN SHIELD AND THE WRAP AROUND PRECIPITATION NOW MOVING ACROSS CENTRAL KY. WHILE THE MAIN PRECIPITATION SHIELD IS CURRENTLY EXITING EASTERN KY...THERE IS CONSIDERABLE WRAP AROUND MOISTURE SO PERIODS OF RAIN WILL CONTINUE THROUGH THE AFTERNOON WITH GENERALLY MVFR CEILINGS...AND SOME LOCAL IFR CONDITIONS. RAIN WILL MIX WITH OR CHANGE TO LIGHT SNOW FOR A TIME TONIGHT AS COLDER AIR WRAPS AROUND THE EXITING LOW PRESSURE SYSTEM. MVFR CEILINGS ARE EXPECTED TO PREVAIL LATE TONIGHT INTO WEDNESDAY. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...HAL/SBH LONG TERM....SHALLENBERGER AVIATION...SBH
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
408 PM EST TUE DEC 27 2011 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL CROSS THE AREA, SPREADING MOSTLY RAIN OVER THE UPPER OHIO VALLEY REGION TODAY BEFORE PRECIPITATION CHANGES TO ALL SNOW TONIGHT. HIGH PRESSURE WILL THEN BUILD IN FOR A DRY MID- WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... THE LATEST RUC MID-LEVEL ANALYSIS INDICATES TWO TROUGH FEATURES THAT ARE SLIGHTLY OFF IN TIMING AND PHASING. THE NORTHERN AND SLOWER FEATURE IS LOCATED ACROSS LAKE MICHIGAN WITH THE SOUTHERN BRANCH ALONG ACROSS WESTERN PENNSYLVANIA. AN 850MB CLOSED LOW IS LOCATED ACROSS NORTH-CENTRAL OHIO. AHEAD OF THIS FEATURE, A WARM WEDGE OF 850 TEMPS AT 1-3C IS BEGINNING TO EDGE EASTWARD OUT THE AREA INTO CENTRAL PA WITH 0C TO -2C 850 TEMPS ENCROACHING EASTERN OHIO. THE WEDGE HAS HELD MOST OF THE DAY WITH RAIN BEING THE DOMINANT TYPE OF PRECIP ACROSS THE AREA. THERE HAS HOWEVER BEEN A MIX ALONG THE I-80 CORRIDOR. AT THE SURFACE A 994MB LOW IS LOCATED ACROSS LAKE ERIE WITH A WIND SHIFT TO NORTHWESTERLY BEHIND IT. ON THE BACK-SIDE OF THE LOW, A DEFORMATION ZONE WITH MODERATE SNOW IS WEAKENING AS IT MOVES INTO WESTERN OHIO. THIS EVENING...THE NORTHERN AND SOUTHERN BRANCHES WILL ATTEMPT TO PHASE INTO A MID-LEVEL TROUGH WITH THE SURFACE LOW MOVING INTO WESTERN NY. THE 850MB LOW WILL PASS NORTHEAST OF THE AREA, WRAPPING COLDER AIR IN BEHIND IT. IN ADDITION, RUC/NAM HINT AT THE RE- DEVELOPMENT OF A 700MB DEFORMATION ZONE, WHICH WILL BRING A SHOT OF MODERATE SNOW TO THE AREA THIS EVENING. THE MOST UNCERTAINTY IN THE FORECAST LIES IN REGARDS TO WHETHER THE DEFORMATION ZONE WILL CONTINUE TO WEAKEN OR RE-DEVELOP. HAVE SIDED WITH IT RE- DEVELOPING. AS SURFACE WINDS SHIFT TO NORTHWESTERLY, THE CHANGEOVER TO SNOW WILL QUICKLY ENSUE. TEMPS WILL REMAIN MID 40S IN LOCATIONS WEST OF CHESTNUT RIDGE WHERE DOWNSLOPING IS OCCURRING. OTHERWISE, TEMPS WILL RANGE FROM THE MID 30S ACROSS THE I-80 CORRIDOR TO THE LOWER 40S ACROSS NORTH-CENTRAL WV. THE COLDEST AIR REMAINS TRAPPED IN THE VALLEYS OF GARRETT COUNTY, WHERE TEMPS IN THE LOWER TO MID 30S WILL ALLOW FOR SOME SLEET TO MIX IN WITH RAIN. WILL CONTINUE TO MONITOR THIS AREA FOR FREEZING RAIN BEFORE THE TURN OVER TO SNOW. TONIGHT...THE TROUGH AND SURFACE LOW WILL SHIFT NORTHEAST OF THE AREA INTO NEW YORK, WITH COLD AIR ADVECTION ALLOWING FOR PRECIPITATION TO QUICKLY TURN OVER TO ALL SNOW. THE 700MB DEFORMATION ZONE WILL CROSS THE AREA, ALLOWING FOR AN INITIAL QUICK BURST OF A HALF OF AN INCH TO AN INCH ACROSS MUCH OF THE AREA. HAVE ISSUED AN SPS TO HIGHLIGHT THIS FEATURE. AFTER THE INITIAL BURST, A NORTHWESTERLY FLOW WILL ALLOW FOR SNOW SHOWERS ACROSS THE AREA. UPSLOPING ACROSS THE RIDGES ALONG WITH A SLIGHTLY FASTER CHANGEOVER FOR AREAS NORTH OF PITTSBURGH WILL ALLOW FOR 2 TO 4 INCHES BY DAWN ON WEDNESDAY. OVERNIGHT LOWS ARE CLOSER TO LAMP GUIDANCE, RANGING FROM THE MID TO UPPER 20S ACROSS THE AREA. THE QUICK DROP BELOW FREEZING BY MIDNIGHT, WILL LEAD TO SOME ICY AND SNOW-COVERED ROADS THROUGH DAWN. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... LAKE EFFECT SNOW SHOWERS WILL LINGER EARLY ON WEDNESDAY, ALTHOUGH DO NOT EXPECT ACCUMULATIONS TO AMOUNT TO MORE THAN AN INCH WITH LOWERED INVERSION HEIGHTS LIMITING INSTABILITY. A SURFACE HIGH WILL THEN BUILD IN THROUGH THURSDAY. TEMPERATURES WILL BE AROUND 5 DEGREES BELOW NORMAL ON WEDNESDAY AND WEDNESDAY NIGHT AS ARCTIC AIR SETTLES INTO THE AREA IN THE WAKE OF THE LOW. THERE IS SOME UNCERTAINTY IN TIMING OF A SERIES OF SHORT WAVES CROSSING THE AERA THURSDAY INTO FRIDAY. SCHC POPS ARE INTRODUCED NORTH OF PITTSBURGH ON THURSDAY, INCREASING TO CHANCE THURSDAY NIGHT, WITH THE BEST CHANCE ON FRIDAY AS A MORE PRONOUNCED TROUGH AXIS CROSSES THE AREA. MODEL THICKNESSES INDICATE A MIX OF RAIN AND SNOW SHOWERS FOR THE AREA, SO DO NOT ANTICIPATE ANY SIGNIFICANT ACCUMULATIONS WITH THE WAVES AS THEY MOVE THROUGH. TEMPS WILL BE AROUND 5 DEGREES ABOVE SEASONAL NORMALS THURSDAY INTO FRIDAY. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... FAST MOVING SYSTEMS IN A PROGRESSIVE FLOW WILL BRING TEMPERATURES AVERAGING CLOSE TO NORMAL AND CHANCES FOR RAIN OR SNOW SHOWERS FOR LATE WEEK INTO THE WEEKEND. STRONGER DISTURBANCE WILL TAP INTO THE NORTHERN BRANCH OF THE JET STREAM BRINGING PROGRESSIVELY COLDER AIR INTO THE REGION BY TUESDAY NIGHT. && .AVIATION /21Z TUESDAY THROUGH SUNDAY/... IFR CONDITIONS WITH LIFR IN AREAS SOUTH OF PITTSBURGH AS LOW LEVEL MOISTURE IS TRAPPED UNDER THE INVERSION. LLWS ALL TAF SITES AS H8 LOW LEVEL JET AT MGW OFF THE NAM AT 2PM INDICATES 81KT JET. WIND SHIFT LINE AND CHANGE OVER TO SNOW IS OVER WESTERN OHIO NOW IN THE VCNTY OF KDAY. LOW IS DEEPENING RAPIDLY AND THAT WIND SHIFT AND CHANGE OVER TO SNOW LINE WILL REACH CWA 23Z VCNTY THROUGH 02Z IFR CAN BE EXPECTED INTO TUESDAY NIGHT AS PRECIPITATION TRANSITIONS TO SNOW IN THE COLD ADVECTION ON THE WRN SIDE OF THE EXITING LOW. CIGS MAY IMPROVE DURING THE OVRNGT TO MVFR LEVELS...BUT IFR VISIBILITY IN SNOW SHOWERS SHOULD CONTINUE. OUTLOOK...WEDNESDAY THROUGH SUNDAY... CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR BY LATE WEDNESDAY AS A WEAK SURFACE RIDGE MOVES EAST. A SERIES OF FAST MOVING WEATHER SYSTEMS WILL THEN CROSS THE REGION DURING THE LATTER HALF OF THE WEEK WITH PERIODIC RESTRICTIONS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR MDZ001. OH...WINTER WEATHER ADVISORY UNTIL 4 AM EST WEDNESDAY FOR OHZ041. PA...WINTER WEATHER ADVISORY UNTIL 4 AM EST WEDNESDAY FOR PAZ007>009-013-015-016. WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR PAZ014-020>023-073>076. WV...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR WVZ023-041. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
205 PM EST TUE DEC 27 2011 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL CROSS THE AREA, SPREADING MOSTLY RAIN OVER THE UPPER OHIO VALLEY REGION TODAY BEFORE PRECIPITATION CHANGES TO ALL SNOW TONIGHT. HIGH PRESSURE WILL THEN BUILD IN FOR A DRY MID- WEEK. && .NEAR TERM /THROUGH 8 PM THIS EVENING/... THE EARLY AFTERNOON UPDATE HAS BEEN ISSUED TO ACCOUNT FOR RECENT TRENDS IN TEMPS AND TO ADD A MIX OF SLEET WITH RAIN FOR GARRETT COUNTY IN MARYLAND. THE LATEST RUC MID-LEVEL ANALYSIS INDICATES TWO TROUGH FEATURES THAT ARE TRYING TO PHASE. THE NORTHERN FEATURE IS LOCATED ACROSS THE UPPER MIDWEST WITH THE SOUTHERN BRANCH ALONG THE OHIO/WEST VIRGINIA BORDER. AN 850MB CLOSED LOW IS LOCATED ACROSS NORTHWEST OHIO. AHEAD OF THIS FEATURE, A WARM WEDGE OF 850 TEMPS AT 2-5C HAS MOVED INTO WESTERN PENNSYLVANIA. THIS HAS ALLOWED PRECIPITATION TO TURN TO MOSTLY RAIN ACROSS THE AREA. THERE HAS HOWEVER BEEN A MIX ALONG THE I-80 CORRIDOR. LAPS ANALYSIS INDICATES THE WET BULB ZERO LINE ACROSS FOREST COUNTY. WET BULBING IN THIS AREA HAS LEAD TO A MIX OF SNOW AND SLEET BEFORE PRECIPITATION TURNS OVER TO RAIN BRIEFLY THIS AFTERNOON. AT THE SURFACE A 997MB LOW IS LOCATED NEAR LIMA, OHIO WITH A WIND SHIFT TO NORTHWESTERLY BEHIND IT. ON THE BACK-SIDE OF THE LOW, A DEFORMATION ZONE HAS DEVELOPED WITH SOME AREAS OF MODERATE SNOW IN INDIANA AND WESTERN OHIO. THIS AFTERNOON...THE NORTHERN AND SOUTHERN BRANCHES WILL ATTEMPT TO PHASE INTO A MID-LEVEL TROUGH WITH THE SURFACE LOW MOVING INTO NORTHWEST PENNSYLVANIA. THE 850MB LOW WILL PASS NORTHEAST OF THE AREA, WRAPPING COLDER AIR IN BEHIND IT. IN ADDITION, RUC/NAM ARE SHOWING 700MB DEFORMATION ZONE SHIFTING ACROSS THE OHIO VALLEY AND BRINGING A SHOT OF MODERATE SNOW TO EASTERN OHIO BY THIS EVENING. AS SURFACE WINDS SHIFT TO NORTHWESTERLY, THE CHANGEOVER TO SNOW WILL QUICKLY ENSUE. TEMPS WILL REMAIN MID 40S IN LOCATIONS WEST OF CHESTNUT RIDGE WHERE DOWNSLOPING IS OCCURRING. OTHERWISE, TEMPS WILL RANGE FROM THE MID 30S ACROSS THE I-80 CORRIDOR TO THE LOWER 40S ACROSS NORTH-CENTRAL WV. THE COLDEST AIR REMAINS TRAPPED IN THE VALLEYS OF GARRETT COUNTY, WHERE TEMPS IN THE LOWER 30S WILL ALLOW FOR SOME SLEET TO MIX IN WITH RAIN. WILL CONTINUE TO MONITOR THIS AREA FOR FREEZING RAIN BEFORE THE TURN OVER TO SNOW. && .SHORT TERM /TONIGHT THROUGH THURSDAY/... THE TROUGH AND SURFACE LOW WILL SHIFT NORTHEAST OF THE AREA INTO NEW YORK, WITH COLD AIR ADVECTION ALLOWING FOR PRECIPITATION TO QUICKLY TURN OVER TO ALL SNOW. A 700MB DEFORMATION ZONE WILL CROSS THE AREA, ALLOWING FOR AN INITIAL QUICK BURST OF 1 TO 2 INCHES ACROSS MUCH OF THE AREA. AFTER THE INITIAL BURST, A NORTHWESTERLY FLOW WILL ALLOW FOR SNOW SHOWERS ACROSS THE AREA. UPSLOPING ACROSS THE RIDGES ALONG WITH A SLIGHTLY FASTER CHANGEOVER AND SOME LAKE ENHANCEMENT FOR AREAS NORTH OF PITTSBURGH WILL ALLOW FOR 2 TO 4 INCHES BY DAWN ON WEDNESDAY. OVERNIGHT LOWS ARE CLOSE TO LAMP GUIDANCE, RANGING FROM THE MID TO UPPER 20S ACROSS THE AREA. THE QUICK DROP BELOW FREEZING BY MIDNIGHT, WILL LEAD TO SOME ICY AND SNOW-COVERED ROADS THROUGH DAWN. LAKE EFFECT SNOW SHOWERS WILL LINGER EARLY ON WEDNESDAY, ALTHOUGH DO NOT EXPECT ACCUMULATIONS TO AMOUNT TO MORE THAN AN INCH WITH LOWERED INVERSION HEIGHTS LIMITING INSTABILITY. A SURFACE HIGH WILL THEN BUILD IN THROUGH THURSDAY. TEMPERATURES WILL BE BELOW NORMAL BUT CONDITIONS SHOULD BE DRY. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... FAST MOVING SYSTEMS IN PROGRESSIVE FLOW WILL BRING TEMPERATURES AVERAGING ABOVE NORMAL AND CHANCES FOR RAIN OR SNOW SHOWERS FOR LATE WEEK INTO THE WEEKEND. LONG TERM PERIOD WAS FORECAST CLOSE TO HPC PROGS WHICH CONTINUE TO TREND TOWARD THE ECMWF. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... IFR CONDITIONS WITH LIFR IN AREAS SOUTH OF PITTSBURGH AS LOW LEVEL MOISTURE IS TRAPPED UNDER THE INVERSION. LLWS ALL TAF SITES AS H8 LOW LEVEL JET AT MGW OFF THE NAM AT 2PM INDICATES 81KT JET. WIND SHIFT LINE AND CHANGE OVER TO SNOW IS OVER WESTERN OHIO NOW IN THE VCNTY OF KDAY. LOW IS DEEPENING RAPIDLY AND THAT WIND SHIFT AND CHANGE OVER TO SNOW LINE WILL REACH CWA 23Z VCNTY THROUGH 02Z IFR CAN BE EXPECTED INTO TUESDAY NIGHT AS PRECIPITATION TRANSITIONS TO SNOW IN THE COLD ADVECTION ON THE WRN SIDE OF THE EXITING LOW. CIGS MAY IMPROVE DURING THE OVRNGT TO MVFR LEVELS...BUT IFR VISIBILITY IN SNOW SHOWERS SHOULD CONTINUE. OUTLOOK...WEDNESDAY THROUGH SUNDAY... CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR BY LATE WEDNESDAY AS A WEAK SURFACE RIDGE MOVES EAST. A SERIES OF FAST MOVING WEATHER SYSTEMS WILL THEN CROSS THE REGION DURING THE LATTER HALF OF THE WEEK WITH PERIODIC RESTRICTIONS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR MDZ001. OH...WINTER WEATHER ADVISORY UNTIL 4 AM EST WEDNESDAY FOR OHZ041. PA...WINTER WEATHER ADVISORY UNTIL 4 AM EST WEDNESDAY FOR PAZ007>009-013-015-016. WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR PAZ014-020>023-073>076. WV...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR WVZ023-041. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1127 AM EST TUE DEC 27 2011 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL CROSS THE AREA, SPREADING A WINTRY MIX OVER THE UPPER OHIO VALLEY REGION TODAY AND THEN ALL SNOW TONIGHT. HIGH PRESSURE WILL THEN BUILD IN FOR A DRY MID-WEEK. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... A LATE MORNING UPDATE HAS BEEN ISSUED TO ADD A SNOW/SLEET MIX TO THE I-80 CORRIDOR AND TO MOVE UP CHANGEOVER TO SNOW BY A FEW HOURS EARLIER AS TEMPS ARE TRENDING COLDER. THE LATEST RUC MID-LEVEL ANALYSIS INDICATES TWO TROUGH FEATURES THAT ARE ATTEMPTING TO PHASE. THE NORTHERN FEATURE IS LOCATED ACROSS THE UPPER MIDWEST WITH THE SOUTHERN BRANCH CROSSING THE TENNESSEE VALLEY. AN 850MB CLOSED LOW HAS DEVELOPED ACROSS INDIANA. AHEAD OF THIS FEATURE, A WARM WEDGE OF 850 TEMPS AT 2-4C HAS MOVED INTO WESTERN PENNSYLVANIA. THIS HAS ALLOWED PRECIPITATION TO TURN TO MOSTLY RAIN ACROSS THE AREA. THERE HAS HOWEVER BEEN A MIX NORTH OF PITTSBURGH. LAPS ANALYSIS INDICATES THE WET BULB ZERO LINE ACROSS THE I-80 CORRIDOR. WET BULBING IN THIS AREA HAS LEAD TO A MIX OF SNOW AND SLEET BEFORE PRECIPITATION TURNS OVER TO RAIN BRIEFLY THIS AFTERNOON. AT THE SURFACE A 999MB LOW IS LOCATED NEAR CINCINNATI, OHIO, WITH A WIND SHIFT TO NORTHWESTERLY BEHIND IT. ON THE BACK-SIDE OF THE LOW, A DEFORMATION ZONE HAS DEVELOPED WITH SOME AREAS OF MODERATE SNOW IN INDIANA. THIS AFTERNOON...THE NORTHERN AND SOUTHERN BRANCHES WILL PHASE INTO A MID-LEVEL TROUGH WITH THE SURFACE LOW MOVING INTO THE NORTHWEST PENNSYLVANIA. EARLY THIS AFTERNOON, WET BULB ZERO LINE WILL CONTINUE TO ALLOW FOR SLEET AND SNOW TO MIX IN, ALTHOUGH NO ACCUMULATION IS EXPECTED WITH TEMPS ABOVE FREEZING. A RAIN/SNOW MIX WILL LINGER THERE UNTIL PRECIP TURNS TO SNOW LATER THIS AFTERNOON. THE 850MB LOW WILL PASS NORTHEAST OF THE AREA, WRAPPING COLDER AIR IN BEHIND IT. IN ADDITION, RUC/NAM ARE SHOWING 700MB DEFORMATION ZONE SHIFTING ACROSS THE OHIO VALLEY AND BRINGING A SHOT OF MODERATE SNOW TO EASTERN OHIO BY THE EARLY EVENING. AS SURFACE WINDS SHIFT TO NORTHWESTERLY, THE CHANGEOVER TO SNOW WILL QUICKLY ENSUE. WITH RECENT TRENDS IN OBS, THIS CHANGEOVER HAS BEEN MOVED UP A FEW HOURS. TEMPS WILL RANGE FROM THE MID 40S ACROSS NORTH- CENTRAL WV TO THE MID 3OS ACROSS THE I-80 CORRIDOR AND REMAIN FAIRLY STEADY UNTIL THE WIND SHIFT OCCUR LATE THIS AFTERNOON IN THE EARLY EVENING. && .SHORT TERM /8 PM THIS EVENING THROUGH THURSDAY/... THE TROUGH AND SURFACE LOW WILL SHIFT NORTHEAST OF THE AREA INTO NEW YORK, WITH COLD AIR ADVECTION ALLOWING FOR PRECIPITATION TO QUICKLY TURN OVER TO ALL SNOW. A 700MB DEFORMATION ZONE WILL CROSS THE AREA, ALLOWING FOR AN INITIAL QUICK BURST OF 1 TO 2 INCHES ACROSS MUCH OF THE AERA. AFTER THE INITIAL BURST, A NORTHWESTERLY FLOW WILL ALLOW FOR SNOW SHOWERS ACROSS THE AREA. UPSLOPING ACROSS THE RIDGES ALONG WITH A SLIGHTLY FASTER CHANGEOVER AND SOME LAKE ENHANCEMENT FOR AREAS NORTH OF PITTSBURGH WILL ALLOW FOR 2 TO 4 INCHES BY DAWN ON WEDNESDAY. OVERNIGHT LOWS ARE CLOSE TO LAMP GUIDANCE, RANGING FROM THE MID TO UPPER 20S ACROSS THE AREA. THE QUICK DROP BELOW FREEZING BY MIDNIGHT, WILL LEAD TO SOME ICY AND SNOW-COVERED ROADS THROUGH DAWN. LAKE EFFECT SNOW SHOWERS WILL LINGER EARLY ON WEDNESDAY, ALTHOUGH DO NOT EXPECT ACCUMULATIONS TO AMOUNT TO MORE THAN AN INCH WITH LOWERED INVERSION HEIGHTS LIMITING INSTABILITY. A SURFACE HIGH WILL THEN BUILD IN THROUGH THURSDAY. TEMPERATURES WILL BE BELOW NORMAL BUT CONDITIONS SHOULD BE DRY. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... FAST MOVING SYSTEMS IN PROGRESSIVE FLOW WILL BRING TEMPERATURES AVERAGING ABOVE NORMAL AND CHANCES FOR RAIN OR SNOW SHOWERS FOR LATE WEEK INTO THE WEEKEND. LONG TERM PERIOD WAS FORECAST CLOSE TO HPC PROGS WHICH CONTINUE TO TREND TOWARD THE ECMWF. && .AVIATION /16Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS CAN BE EXPECTED IN THE IMMEDIATE POST DAWN ALTHOUGH CLOUD LEVEL WILL BE STEADILY LOWERING AS MOISTURE BEING PUSHED IN ADVANCE OF APPROACHING LOW PRES OVERCOMES DEEP DRY LAYER OVR THE UPR OHIO REGION. CONFIDENCE IS HIGH THAT CONDITIONS WILL DETERIORATE TO IFR BY MIDDAY AS THAT LOW CONTS A NEWD TREK AND THE UPR OHIO VALLEY ATMOSPHERE SATURATES. PROJECTED PASSAGE OF THE LOW ACRS OHIO WOULD ENSURE THAT WARM ADVECTION ON THE ERN FLANK OF THAT SYSTEM WILL CHANGE ANY MIXED PRECIP AT KDUJ/KFKL BRIEFLY TO RAIN THIS AFTERNOON BEFORE PRECIP TURNS BACK OVER TO ALL SNOW. OTHER CONCERN FOR THE MIDDAY PERIOD WL BE THE LLWS POTENTIAL AS WIND SPEED ABOVE THE BOUNDARY LAYER WL INCRS SIGNIFICANTLY WITH PASSAGE OF THE LOW. CONFIDENCE IN THAT POTENTIAL IS SUFFICIENTLY HIGH TO INCLUDE IN ALL TAFS. IFR CAN BE EXPECTED INTO TUESDAY NIGHT AS PRECIPITATION TRANSITIONS TO SNOW IN THE COLD ADVECTION ON THE WRN SIDE OF THE EXITING LOW. CIGS MAY IMPROVE DURING THE OVRNGT TO MVFR LEVELS...BUT IFR VISIBILITY IN SNOW SHOWERS SHOULD CONT TO PLAGUE AREA PORTS. OUTLOOK...WEDNESDAY THROUGH SATURDAY... CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR BY LATE WEDNESDAY AS A WEAK SURFACE RIDGE MOVES EAST. A SERIES OF FAST MOVING WEATHER SYSTEMS WILL THEN CROSS THE REGION DURING THE LATTER HALF OF THE WEEK WITH PERIODIC RESTRICTIONS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR MDZ001. OH...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM EST WEDNESDAY FOR OHZ041. PA...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM EST WEDNESDAY FOR PAZ007>009-013-015-016. WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR PAZ014-020>023-073>076. WV...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR WVZ023-041. && $$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1242 PM EST TUE DEC 27 2011 LATEST UPDATE...AVIATION... .SYNOPSIS...(450 AM EST TUE DEC 27 2011) LOW PRESSURE MOVING NORTH FROM THE SOUTHERN US WILL COMBINE WITH COLDER AIR MOVING SOUTH FROM CANADA TO PRODUCE SOME LIGHT SNOW TODAY. LIGHT RAIN MAY MIX WITH THE SNOW...ESPECIALLY THIS MORNING. AN INCH OR TWO OF ACCUMULATION IS POSSIBLE WITH GREATEST AMOUNTS SOUTHEAST OF A KALAMAZOO TO LANSING LINE. WEDNESDAY WILL BE OUR COLDEST DAY WITH HIGHS AROUND 30. AFTER THAT HIGHS WILL CLIMB TO NEAR 40 THROUGH THE WEEKEND. A CLIPPER SYSTEM WILL BRING A CHANCE OF RAIN AND SNOW TO THE REGION THURSDAY. && .SHORT TERM...(1115 AM EST TUE DEC 27 2011) (TODAY THROUGH THURSDAY) * ACCUMULATING SNOW WILL TAPER TO FLURRIES/LIGHT RAIN EARLY THIS AFTERNOON WITH SNOW TOTALS OF 1 TO 3 INCHES...PRIMARILY GRASSY SURFACES...SIGNIFICANT WEATHER ADVISORY WAS ISSUED AT 10 AM. * GUSTY WINDS ALONG COAST THIS EVENING WILL BE LOOKING AT POSSIBLE WIND ADVISORY FOR THE COAST... RADAR INDICATING TWO BANDS OF MODERATE SNOW AT THE PRESENT TIME. BOTH ARE ORIENTED SSW-NNE WITH ONE FROM KGRR TO KMOP...WITH THE SECOND BAND ALONG A KOEB...KJXN...KFNT LINE. BOTH BANDS ARE SLOWLY MOVING EAST AND ARE EXPECTED TO WEAKEN AS THE MIDLEVEL FRONTOGENESIS SHIFT TO THE NORTHEAST AND SURFACE COLD FRONT SWEEPS EASTWARD THIS AFTERNOON. THE HRRR RUC HAS HAD A REALLY GOOD HANDLE ON THE EVOLUTION OF THE SYSTEM THIS MORNING AND HAVE LEVERAGED IT HEAVILY IN UPDATING SNOWFALL GRIDS. ALTHOUGH...HALF OF THE SNOW HAS FALLEN...LOOKS LIKE LOCAL TOTALS OF 3 INCHES ARE LIKELY. TEMPERATURES ARE EXPECTED TO RISE INTO THE MID 30S THIS AFTERNOON AS THE SNOW TAPERS OFF AND MAY EVEN END AS A MIX WITH RAIN BEFORE ENDING. THIS EVENING WINDS WILL KICK UP AS COLDER AIR FLOWS IN BEHIND THE LOW AS IT MOVES BY TO THE SOUTHEAST. STRONGEST WINDS WILL BE NEAR THE LAKE SHORE. PCPN WILL DIMINISH THIS EVENING. THERE MAY BE A FEW SNOW SHOWERS ALONG THE LAKE SHORE IN NORTH FLOW AS H8 TEMPS FALL BRIEFLY TO AROUND -12C. MOISTURE IS SHALLOW THOUGH AND NOTHING ORGANIZED IS EXPECTED. THE NEXT CLIPPER WILL MOVE TOWARD THE REGION WEDNESDAY NIGHT AND THURSDAY. AS HAS BEEN TYPICAL LATELY...THIS SYSTEM WILL SCOOT BY TO THE NORTH. THAT MEANS WE/LL SEE SOME WARMER AIR FLOW INTO THE CWA AND MIXED RAIN/SNOW IS EXPECTED IN THE SRN CWA WITH MORE SNOW IN THE NORTH. APPRECIABLE ACCUMS ARE NOT EXPECTED. && .LONG TERM...(450 AM EST TUE DEC 27 2011) (THURSDAY NIGHT THROUGH MONDAY) ZONAL FLOW IS FORECAST TO CONTINUE OVER THE LOWER 48 FOR MUCH OF THE LONG TERM...TRANSITIONING TO AN EASTERN TROUGH/WESTERN RIDGE TOWARD THE END OF THE PERIOD. GENERALLY LIGHT PRECIPITATION IS EXPECTED THROUGH THE PERIOD. TIMING ISSUES ARE ALWAYS A CONCERN IN ZONAL FLOW AND THIS FORECAST IS NO EXCEPTION. FIRST WEAK SHORTWAVE TO DEAL WITH IS MOVING THROUGH THE GREAT LAKES THURSDAY NIGHT. LOOKS LIKE MAINLY LIGHT SNOW...WITH QPF TOTALS THAT ARE ON THE ORDER OF 0.10 OR LESS...SO NO ISSUES EXPECTED. THE EUROPEAN HAS ANOTHER WAVE AFFECTING THE AREA FRIDAY INTO FRIDAY NIGHT..WHILE THE GFS HAS RIDGING BUILDING IN. MAINTAINED SOME SMALL POPS AT THIS POINT. HOPING FOR SOME BETTER CONSISTENCY...OBVIOUSLY LOW CONFIDENCE OUT IN THE FRIDAY AND FRIDAY NIGHT TIME FRAME. SATURDAY SHOULD BE MAINLY DRY WITH THE NEXT SYSTEM MOVING IN FOR LATER IN THE WEEKEND. TIMING ISSUES CONTINUE WITH THE GFS BLASTING A COLD FRONT THROUGH QUICKER...BY SUNDAY MORNING. THE EURO HOLDS THE FRONT UP BY 12 HOURS OR SO. COLDER AIR IS PROGD TO FILTER IN BEHIND THIS SYSTEM...WITH THE EURO INDICATING -16 C AIR OVER LAKE MICHIGAN MONDAY AFTERNOON. GIVEN CONSISTENCY/TIMING ISSUES THE BULK OF THE LONG TERM...LOW CONFIDENCE OVERALL. MADE LITTLE IN THE WAY OF CHANGES AT THIS POINT. && .AVIATION...(1242 PM EST TUE DEC 27 2011) THE BACK EDGE OF THE STEADY SNOW EXTENDED FROM MOP TO AZO AS OF 1730Z. EAST OF THIS LINE IFR AND LIFR CONDITIONS PREVAIL. MEANWHILE TO THE WEST OF THIS LINE VSBYS GREATLY IMPROVE...HOWEVER CEILINGS REMAIN LARGELY IFR. THE SNOW SWATH AND LOWER VSBYS WILL CONTINUE TO END FROM WEST TO EAST...REACHING LAN AND JXN AROUND 00Z. SURFACE WINDS AND MIXING WILL GREATLY INCREASE EARLY THIS EVENING. THIS WILL HELP MOVE OUT ANY REMAINING IFR CEILINGS BY 03Z. VFR/MVFR CONDITIONS ARE EXPECTED OVERNIGHT...HOWEVER NW WINDS WILL OCCASIONALLY GUST AS HIGH AS 30 KNOTS. THESE WINDS WILL TAPER OFF TOWARD DAYBREAK ON WED. CONDITIONS FINALLY LOOK FAVORABLE FOR VFR FLYING WITH LIGHTER WINDS BY ABOUT 10Z WED AND SHOULD PREVAIL THROUGH 18Z WED. && .MARINE...(1115 AM EST TUE DEC 27 2011) WINDS WILL BEGIN RAMPING UP EARLY THIS AFTERNOON AND GUST TO GALE FORCE BY EARLY EVENING. GALE WARNING THROUGH THIS EVENING WITH GUST AROUND 35 KTS. && .HYDROLOGY...(450 AM EST TUE DEC 27 2011) NO SIGNIFICANT CHANGES TO RIVERS EXPECTED FOR THE NEXT SEVERAL DAYS. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...GALE WARNING ALL AREAS THROUGH TONIGHT. && $$ SYNOPSIS: 93 SHORT TERM: COBB LONG TERM: DUKE AVIATION: JK MARINE: COBB HYDROLOGY: 93
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1115 AM EST TUE DEC 27 2011 LATEST UPDATE...MARINE AND SHORT TERM... .SYNOPSIS...(450 AM EST TUE DEC 27 2011) LOW PRESSURE MOVING NORTH FROM THE SOUTHERN US WILL COMBINE WITH COLDER AIR MOVING SOUTH FROM CANADA TO PRODUCE SOME LIGHT SNOW TODAY. LIGHT RAIN MAY MIX WITH THE SNOW...ESPECIALLY THIS MORNING. AN INCH OR TWO OF ACCUMULATION IS POSSIBLE WITH GREATEST AMOUNTS SOUTHEAST OF A KALAMAZOO TO LANSING LINE. WEDNESDAY WILL BE OUR COLDEST DAY WITH HIGHS AROUND 30. AFTER THAT HIGHS WILL CLIMB TO NEAR 40 THROUGH THE WEEKEND. A CLIPPER SYSTEM WILL BRING A CHANCE OF RAIN AND SNOW TO THE REGION THURSDAY. && .SHORT TERM...(1115 AM EST TUE DEC 27 2011) (TODAY THROUGH THURSDAY) * ACCUMULATING SNOW WILL TAPER TO FLURRIES/LIGHT RAIN EARLY THIS AFTERNOON WITH SNOW TOTALS OF 1 TO 3 INCHES...PRIMARILY GRASSY SURFACES...SIGNIFICANT WEATHER ADVISORY WAS ISSUED AT 10 AM. * GUSTY WINDS ALONG COAST THIS EVENING WILL BE LOOKING AT POSSIBLE WIND ADVISORY FOR THE COAST... RADAR INDICATING TWO BANDS OF MODERATE SNOW AT THE PRESENT TIME. BOTH ARE ORIENTED SSW-NNE WITH ONE FROM KGRR TO KMOP...WITH THE SECOND BAND ALONG A KOEB...KJXN...KFNT LINE. BOTH BANDS ARE SLOWLY MOVING EAST AND ARE EXPECTED TO WEAKEN AS THE MIDLEVEL FRONTOGENSIS SHIFT TO THE NORTHEAST AND SURFACE COLD FRONT SWEEPS EASTWARD THIS AFTERNOON. THE HRRR RUC HAS HAD A REALLY GOOD HANDLE ON THE EVOLUTION OF THE SYSTEM THIS MORNING AND HAVE LEVERAGED IT HEAVILY IN UPDATING SNOWFALL GRIDS. ALTHOUGH...HALF OF THE SNOW HAS FALLEN...LOOKS LIKE LOCAL TOTALS OF 3 INCHES ARE LIKELY. TEMPERATURES ARE EXPECTED TO RISE INTO THE MID 30S THIS AFTERNOON AS THE SNOW TAPERS OFF AND MAY EVEN END AS A MIX WITH RAIN BEFORE ENDING. THIS EVENING WINDS WILL KICK UP AS COLDER AIR FLOWS IN BEHIND THE LOW AS IT MOVES BY TO THE SOUTHEAST. STRONGEST WINDS WILL BE NEAR THE LAKE SHORE. PCPN WILL DIMINISH THIS EVENING. THERE MAY BE A FEW SNOW SHOWERS ALONG THE LAKE SHORE IN NORTH FLOW AS H8 TEMPS FALL BRIEFLY TO AROUND -12C. MOISTURE IS SHALLOW THOUGH AND NOTHING ORGANIZED IS EXPECTED. THE NEXT CLIPPER WILL MOVE TOWARD THE REGION WEDNESDAY NIGHT AND THURSDAY. AS HAS BEEN TYPICAL LATELY...THIS SYSTEM WILL SCOOT BY TO THE NORTH. THAT MEANS WE/LL SEE SOME WARMER AIR FLOW INTO THE CWA AND MIXED RAIN/SNOW IS EXPECTED IN THE SRN CWA WITH MORE SNOW IN THE NORTH. APPRECIABLE ACCUMS ARE NOT EXPECTED. && .LONG TERM...(450 AM EST TUE DEC 27 2011) (THURSDAY NIGHT THROUGH MONDAY) ZONAL FLOW IS FORECAST TO CONTINUE OVER THE LOWER 48 FOR MUCH OF THE LONG TERM...TRANSITIONING TO AN EASTERN TROUGH/WESTERN RIDGE TOWARD THE END OF THE PERIOD. GENERALLY LIGHT PRECIPITATION IS EXPECTED THROUGH THE PERIOD. TIMING ISSUES ARE ALWAYS A CONCERN IN ZONAL FLOW AND THIS FORECAST IS NO EXCEPTION. FIRST WEAK SHORTWAVE TO DEAL WITH IS MOVING THROUGH THE GREAT LAKES THURSDAY NIGHT. LOOKS LIKE MAINLY LIGHT SNOW...WITH QPF TOTALS THAT ARE ON THE ORDER OF 0.10 OR LESS...SO NO ISSUES EXPECTED. THE EUROPEAN HAS ANOTHER WAVE AFFECTING THE AREA FRIDAY INTO FRIDAY NIGHT..WHILE THE GFS HAS RIDGING BUILDING IN. MAINTAINED SOME SMALL POPS AT THIS POINT. HOPING FOR SOME BETTER CONSISTENCY...OBVIOUSLY LOW CONFIDENCE OUT IN THE FRIDAY AND FRIDAY NIGHT TIME FRAME. SATURDAY SHOULD BE MAINLY DRY WITH THE NEXT SYSTEM MOVING IN FOR LATER IN THE WEEKEND. TIMING ISSUES CONTINUE WITH THE GFS BLASTING A COLD FRONT THROUGH QUICKER...BY SUNDAY MORNING. THE EURO HOLDS THE FRONT UP BY 12 HOURS OR SO. COLDER AIR IS PROGD TO FILTER IN BEHIND THIS SYSTEM...WITH THE EURO INDICATING -16 C AIR OVER LAKE MICHIGAN MONDAY AFTERNOON. GIVEN CONSISTENCY/TIMING ISSUES THE BULK OF THE LONG TERM...LOW CONFIDENCE OVERALL. MADE LITTLE IN THE WAY OF CHANGES AT THIS POINT. && .AVIATION...(715 AM EST TUE DEC 27 2011) PRECIPITATION HAS OVERSPREAD ALL OF THE TAF SITES THIS MORNING...WITH A MIXTURE OF RAIN AND SNOW ACROSS THE AREA. THE TREND SHOULD BE TO ALL SNOW BY MID MORNING. CEILINGS ARE TRENDING DOWN AND THAT SHOULD CONTINUE TO BE THE CASE THROUGH THE MORNING HOURS. BY LATE MORNING...CONDITIONS WILL BE POOR RANGING FROM IFR TO LIFR. AN IMPROVEMENT WILL OCCUR SLOWLY THIS AFTERNOON FROM WEST TO EAST AS THE SYSTEM RESPONSIBLE FOR THE SNOW PULLS AWAY TO THE EAST. MVFR CONDITIONS ARE EXPECTED BY MID TO LATE AFTERNOON. CONDITIONS WILL IMPROVE TO VFR TONIGHT...WITH SOME VFR CEILINGS EXPECTED OFF OF LAKE MICHIGAN. IT WILL BECOME WINDY THIS AFTERNOON...ESPECIALLY AT KMKG WITH A NORTHWEST WIND OFF THE LAKE. GUSTS WILL RANGE FROM 20 TO 30 KNOTS AT MOST LOCATIONS THIS AFTERNOON AND EVENING FROM THE NORTHWEST. && .MARINE...(1115 AM EST TUE DEC 27 2011) WINDS WILL BEGIN RAMPING UP EARLY THIS AFTERNOON AND GUST TO GALE FORCE BY EARLY EVENING. GALE WARNING THROUGH THIS EVENING WITH GUST AROUND 35 KTS. && .HYDROLOGY...(450 AM EST TUE DEC 27 2011) NO SIGNIFICANT CHANGES TO RIVERS EXPECTED FOR THE NEXT SEVERAL DAYS. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...GALE WARNING ALL AREAS THROUGH TONIGHT. && $$ SYNOPSIS: 93 SHORT TERM: COBB LONG TERM: DUKE AVIATION: DUKE MARINE: COBB HYDROLOGY: 93
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1143 PM CST WED DEC 28 2011 .AVIATION... /06Z TAF ISSUANCE/ THREAT FOR FREEZING RAIN LINGERS AT KSTC...KRNH AND KEAU UNTIL 08Z AS LOW PRESSURE AND A WARM FRONT MOVE THROUGH. CEILINGS ARE BEGINNING TO DETERIORATE ALONG AND AHEAD OF A WARM FRONT. EXPECT MVFR TO SETTLE IN BETWEEN 09Z AND 11Z AND LAST THROUGH MUCH OF THE MORNING BEFORE SCATTERING OUT IN THE EARLY AFTERNOON. ANOTHER WAVE OF LOW PRESSURE WILL MOVE ACROSS THURSDAY NIGHT...MUCH LIKE THE CURRENT ONE. HOWEVER...THE LOW TOMORROW NIGHT WILL BE STRONGER AND PROFILE DATA SUGGESTS IT WILL BE COLDER. HENCE...SNOW IS THE MAIN EVENT. MODEL TRENDS ARE PAINTING A PRETTY BLEAK PICTURE FOR KMSP AND KRNH AND KEAU WITH SNOW ACCUMULATION DURING THE LATE EVENING AND OVERNIGHT HOURS. MVFR OR LOWER CEILINGS/VISIBILITIES WILL ACCOMPANY THE SNOW. KMSP...LIGHT RAIN PUSHING EAST OF THE AIRFIELD WITH BKN-OVC035-040 FOR A FEW HOURS. MVFR CEILINGS STILL EXPECTED TOWARDS DAYBREAK IN THE WAKE OF A LOW PRESSURE SYSTEM MOVING INTO WEST CENTRAL MN ATTM. THESE SHOULD PERSIST THROUGH THE MORNING WITH A VFR AFTERNOON. POTENTIAL FOR MVFR OR LOWER CEILINGS QUITE HIGH FOR THURSDAY NIGHT AND FRIDAY MORNING AS ANOTHER WAVE OF LOW PRESSURE MOVES THROUGH. SNOW SHOULD ACCOMPANY THIS ONE TOMORROW NIGHT WITH SOME ACCUMULATION POSSIBLE. && .UPDATED... /ISSUED 816 PM CST WED DEC 28 2011/ HAVE ISSUED A WINTER WEATHER ADVISORY THROUGH 3 AM THURSDAY FOR MUCH OF CENTRAL MN AND WEST CENTRAL WI. LIGHT RAIN HAS SPREAD INTO WEST CENTRAL MN THIS EVENING AHEAD OF A LOW PRESSURE SYSTEM OVER ND. TEMPERATURES ARE IN THE MIDDLE 30S AROUND ALEXANDRIA BUT FURTHER EAST TEMPERATURES ARE AT OR BELOW FREEZING. PAVEMENT TEMPERATURES ACROSS CENTRAL MN AND PARTS OF WEST CENTRAL WI ARE AROUND 30 DEGREES AS WELL. HENCE...THE POTENTIAL FOR FREEZING RAIN IS INCREASING. COMPLICATING MATTERS IS THAT ICE INCREASES IN THE COLUMN TO THE NORTH AND EAST OF THE TWIN CITIES WITH THE PRECIP TYPE MORE LIKELY TO BE SNOW WITH A CHANCE OF FREEZING RAIN. && .DISCUSSION... /ISSUED 352 PM CST WED DEC 28 2011/ SUMMARY...PATTERN IS A BIT MORE ACTIVE OVER THE NEXT SEVERAL DAYS IN TERMS OF CHANCES OF PRECIPITATION THAN IT HAS BEEN IN QUITE SOME TIME. OVERALL...THE OUTLOOK REMAINS WARM SO THE PRECIP EVENTS EXPECTED TONIGHT...THURSDAY NIGHT AND SATURDAY NIGHT WILL LIKELY HAVE SOME LIQUID PRECIPITATION ASSOCIATED WITH EACH OF THEM. NO MAJOR SYSTEMS EXPECTED AND MAXIMUM QPF WITH EACH EVENT SHOULD LARGELY BE BELOW A QUARTER INCH...A COUPLE OUTLIER RUNS OF THE NAM/GEM WOULD SUGGEST HIGHER QPF TOTALS WITH THE THURSDAY NIGHT AND SATURDAY NIGHT SYSTEMS. THE INTERIOR OF CANADA HAS COOLED SINCE THE LAST TIME I WAS ON A FORECAST SHIFT LATE LAST WEEK...BUT STILL NO TRUE ARCTIC AIR ENCROACHING ON THE US CONUS. THE ARCTIC AIR IS STILL BEING CONFINED TO THE HIGHER LATITUDES...LARGELY ABOVE 55-60 DEGREES NORTH. PACIFIC AIR MASSES WILL CONTINUE TO IMPACT THE US THROUGH THE END OF THE YEAR. PROGRESSIVE UPPER FLOW WILL BE FEATURED AS A SERIES OF DISTURBANCES SURGE FROM THE NORTHEASTERN PACIFIC AND INTO THE PACIFIC NORTHWEST. THE SOUTHWARD EXTENT OF THIS UPPER TROUGH SHOULD BE LIMITED BY A RIDGE ACROSS THE SOUTHWEST US. AS A RESULT...THE SWATH OF PRECIPITATION SHOULD NOT EXTEND MUCH FARTHER SOUTH THAN 40 DEGREES NORTH. THIS WILL KEEP MN AND WI UNDER THE GUN FOR A FEW LIGHT PRECIPITATION EVENTS OVER THE COMING DAYS. THE FAST MOVING FLOW ALOFT WILL KEEP UNSETTLED CONDITIONS IN PLACE FOR MUCH OF THE PACIFIC NORTHWEST...NORTHERN ROCKIES AND UPPER MISSISSIPPI VALLEY THROUGH THE WEEKEND. THE FIRST IN A PAIR OF SYSTEMS IS CURRENTLY MOVING OUT OF THE NORTHERN ROCKIES AND INTO THE NORTHERN PLAINS. LIGHT RAIN IS RAPIDLY PUSHING INTO THE EASTERN DAKOTAS LATE THIS AFTERNOON AND THE HRRR TREND IS TAKE THE LIGHT RAIN INTO WESTERN MN BETWEEN 00-03Z. IF THE CURRENT TRENDS HOLD...MOST OF THE PRECIP WILL PUSH OUT OF THE FORECAST AREA BETWEEN 06-09Z...A BIT FASTER THAN THE CURRENT FORECAST INDICATES. ALSO SOME QUESTION WHETHER OR NOT THE MIXED PRECIPITATION WILL REALLY PAN OUT IN PARTS OF CENTRAL/SOUTHERN MN. COOLING WILL BE TOUGH WITH CLOUD COVER AND WEAK WARM AIR ADVECTION. IT MIGHT END UP BEING NEARLY ALL LIGHT RAIN RATHER THAN SNOW OR FREEZING RAIN. IN THE EXTENDED...INCREASINGLY MERIDIONAL FLOW WILL LEAD TO MORE AMPLIFIED TROUGHS ACROSS THE EASTERN PACIFIC THROUGH THE GREAT LAKES WITH RIDGING SANDWICHED IN BETWEEN. MOST OF THE GUIDANCE AGREES ON THIS PATTERN...OUTSIDE THE 00Z GFS WHICH WAS BROAD AND FLAT WITH THE EASTERN TROUGH DESPITE ITS AMPLIFIED RIDGE UPSTREAM. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL 3 AM CST THURSDAY FOR BENTON- CHISAGO-ISANTI-KANABEC-MILLE LACS-MORRISON-SHERBURNE- STEARNS-TODD. WI...WINTER WEATHER ADVISORY UNTIL 3 AM CST THURSDAY FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-POLK-RUSK-ST. CROIX. && $$ RAH/RAH/CLF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
816 PM CST WED DEC 28 2011 .UPDATE... HAVE ISSUED A WINTER WEATHER ADVISORY THROUGH 3 AM THURSDAY FOR MUCH OF CENTRAL MN AND WEST CENTRAL WI. LIGHT RAIN HAS SPREAD INTO WEST CENTRAL MN THIS EVENING AHEAD OF A LOW PRESSURE SYSTEM OVER ND. TEMPERATURES ARE IN THE MIDDLE 30S AROUND ALEXANDRIA BUT FURTHER EAST TEMPERATURES ARE AT OR BELOW FREEZING. PAVEMENT TEMPERATURES ACROSS CENTRAL MN AND PARTS OF WEST CENTRAL WI ARE AROUND 30 DEGREES AS WELL. HENCE...THE POTENTIAL FOR FREEZING RAIN IS INCREASING. COMPLICATING MATTERS IS THAT ICE INCREASES IN THE COLUMN TO THE NORTH AND EAST OF THE TWIN CITIES WITH THE PRECIP TYPE MORE LIKELY TO BE SNOW WITH A CHANCE OF FREEZING RAIN. && .DISCUSSION... /ISSUED 352 PM CST WED DEC 28 2011/ SUMMARY...PATTERN IS A BIT MORE ACTIVE OVER THE NEXT SEVERAL DAYS IN TERMS OF CHANCES OF PRECIPITATION THAN IT HAS BEEN IN QUITE SOME TIME. OVERALL...THE OUTLOOK REMAINS WARM SO THE PRECIP EVENTS EXPECTED TONIGHT...THURSDAY NIGHT AND SATURDAY NIGHT WILL LIKELY HAVE SOME LIQUID PRECIPITATION ASSOCIATED WITH EACH OF THEM. NO MAJOR SYSTEMS EXPECTED AND MAXIMUM QPF WITH EACH EVENT SHOULD LARGELY BE BELOW A QUARTER INCH...A COUPLE OUTLIER RUNS OF THE NAM/GEM WOULD SUGGEST HIGHER QPF TOTALS WITH THE THURSDAY NIGHT AND SATURDAY NIGHT SYSTEMS. THE INTERIOR OF CANADA HAS COOLED SINCE THE LAST TIME I WAS ON A FORECAST SHIFT LATE LAST WEEK...BUT STILL NO TRUE ARCTIC AIR ENCROACHING ON THE US CONUS. THE ARCTIC AIR IS STILL BEING CONFINED TO THE HIGHER LATITUDES...LARGELY ABOVE 55-60 DEGREES NORTH. PACIFIC AIR MASSES WILL CONTINUE TO IMPACT THE US THROUGH THE END OF THE YEAR. PROGRESSIVE UPPER FLOW WILL BE FEATURED AS A SERIES OF DISTURBANCES SURGE FROM THE NORTHEASTERN PACIFIC AND INTO THE PACIFIC NORTHWEST. THE SOUTHWARD EXTENT OF THIS UPPER TROUGH SHOULD BE LIMITED BY A RIDGE ACROSS THE SOUTHWEST US. AS A RESULT...THE SWATH OF PRECIPITATION SHOULD NOT EXTEND MUCH FARTHER SOUTH THAN 40 DEGREES NORTH. THIS WILL KEEP MN AND WI UNDER THE GUN FOR A FEW LIGHT PRECIPITATION EVENTS OVER THE COMING DAYS. THE FAST MOVING FLOW ALOFT WILL KEEP UNSETTLED CONDITIONS IN PLACE FOR MUCH OF THE PACIFIC NORTHWEST...NORTHERN ROCKIES AND UPPER MISSISSIPPI VALLEY THROUGH THE WEEKEND. THE FIRST IN A PAIR OF SYSTEMS IS CURRENTLY MOVING OUT OF THE NORTHERN ROCKIES AND INTO THE NORTHERN PLAINS. LIGHT RAIN IS RAPIDLY PUSHING INTO THE EASTERN DAKOTAS LATE THIS AFTERNOON AND THE HRRR TREND IS TAKE THE LIGHT RAIN INTO WESTERN MN BETWEEN 00-03Z. IF THE CURRENT TRENDS HOLD...MOST OF THE PRECIP WILL PUSH OUT OF THE FORECAST AREA BETWEEN 06-09Z...A BIT FASTER THAN THE CURRENT FORECAST INDICATES. ALSO SOME QUESTION WHETHER OR NOT THE MIXED PRECIPITATION WILL REALLY PAN OUT IN PARTS OF CENTRAL/SOUTHERN MN. COOLING WILL BE TOUGH WITH CLOUD COVER AND WEAK WARM AIR ADVECTION. IT MIGHT END UP BEING NEARLY ALL LIGHT RAIN RATHER THAN SNOW OR FREEZING RAIN. IN THE EXTENDED...INCREASINGLY MERIDIONAL FLOW WILL LEAD TO MORE AMPLIFIED TROUGHS ACROSS THE EASTERN PACIFIC THROUGH THE GREAT LAKES WITH RIDGING SANDWICHED IN BETWEEN. MOST OF THE GUIDANCE AGREES ON THIS PATTERN...OUTSIDE THE 00Z GFS WHICH WAS BROAD AND FLAT WITH THE EASTERN TROUGH DESPITE ITS AMPLIFIED RIDGE UPSTREAM. && .AVIATION... /00Z TAF ISSUANCE/ LOW PRESSURE AREA OVER ND TO MOVE INTO CENTRAL MN OVERNIGHT AND INTO WEST CENTRAL WI BY THURSDAY MORNING. MAINLY VFR CIGS TO START THE EVENING BUT LOWER TO MVFR LATE TONIGHT OVER CENTRAL MN. A RAIN AND SNOW MIX IS LIKELY FROM NEAR KAXN TO KMSP...WITH MAINLY SNOW TO THE NORTHEAST OF THAT LINE. VSBYS COULD GO BRIEFLY INTO THE IFR CATEGORY. THERE IS AS RISK OF FREEZING RAIN IN THE ABOVE MENTIONED CORRIDOR AS WELL. THE LENGTH OF TIME OF THE PRECIP WILL NOT BE LONG GENERALLY LESS THAN 3 HOURS AS THE SYSTEM MOVES ACROSS THE AREA OVERNIGHT. THERE IS A LOW RISK OF IFR CIGS THURSDAY MORNING OVER CENTRAL MN BEHIND THE LOW PRESSURE AREA. WILL INDICATE A SCT LAYER AT KAXN AND LOWER THE CIG A BIT AT KSTC. MVFR CIGS WILL SCT OUT OVER PARTS OF WEST CENTRAL MN DURING THE AFTERNOON BEFORE LOWER VFR CIGS MOVE IN FOR THE NEXT SYSTEM BY THE END OF THE TAF PREIOD. HAVE ALSO INDICATED SOME RAIN BEGINNING AT KRWF AFTER 22Z. WINDS SOUTH TO SOUTHEAST OVERNIGHT BECOMING NORTHWEST BEHIND THE LOW PRESSURE. SPEEDS GENERALLY AT OR BELOW 10 KNOTS. KMSP...VFR CIGS AS THE PRECIPITATION MOVES IN...THEN CLOSE TO MVFR DURING THE BEST WINDOW OF PRECIP. PRECIPITATION TYPE PROBLEMATIC AS WE WILL BE ON THE EDGE OF A RAIN/SNOW LINE. WILL NEED TO WATCH THE TEMP TRENDS AS PRECIP MOVES IN AS THERE IS A LOW RISK OF FREEZING RAIN. FOR NOW WILL GO WITH A RAIN AND SNOW MIX. HAVE INDICATED JUST MVFR VSBYS BUT NEED TO WATCH THAT AS WELL. WILL BE BRIEF IF IT DOES GO DOWN TO IFR. MVFR CIGS SHOULD MOVE IN AT OR AFTER 12Z...AND PERSIST THROUGH THE MORNING. THE NEXT SYSTEM TO BRING IN A CHANCE OF RAIN OR SNOW AFTER 00Z FRIDAY. THERE MAY BE A WINDOW OF VFR CONDITIONS FOR THE AFTERNOON. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL 3 AM CST THURSDAY FOR BENTON- CHISAGO-ISANTI-KANABEC-MILLE LACS-MORRISON-SHERBURNE- STEARNS-TODD. WI...WINTER WEATHER ADVISORY UNTIL 3 AM CST THURSDAY FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-POLK-RUSK-ST. CROIX. && $$ RAH/CLF/JPR
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
612 PM CST WED DEC 28 2011 .UPDATE... .AVIATION.../00Z TAF ISSUANCE/ LOW PRESSURE AREA OVER ND TO MOVE INTO CENTRAL MN OVERNIGHT AND INTO WEST CENTRAL WI BY THURSDAY MORNING. MAINLY VFR CIGS TO START THE EVENING BUT LOWER TO MVFR LATE TONIGHT OVER CENTRAL MN. A RAIN AND SNOW MIX IS LIKELY FROM NEAR KAXN TO KMSP...WITH MAINLY SNOW TO THE NORTHEAST OF THAT LINE. VSBYS COULD GO BRIEFLY INTO THE IFR CATEGORY. THERE IS AS RISK OF FREEZING RAIN IN THE ABOVE MENTIONED CORRIDOR AS WELL. THE LENGTH OF TIME OF THE PRECIP WILL NOT BE LONG GENERALLY LESS THAN 3 HOURS AS THE SYSTEM MOVES ACROSS THE AREA OVERNIGHT. THERE IS A LOW RISK OF IFR CIGS THURSDAY MORNING OVER CENTRAL MN BEHIND THE LOW PRESSURE AREA. WILL INDICATE A SCT LAYER AT KAXN AND LOWER THE CIG A BIT AT KSTC. MVFR CIGS WILL SCT OUT OVER PARTS OF WEST CENTRAL MN DURING THE AFTERNOON BEFORE LOWER VFR CIGS MOVE IN FOR THE NEXT SYSTEM BY THE END OF THE TAF PREIOD. HAVE ALSO INDICATED SOME RAIN BEGINNING AT KRWF AFTER 22Z. WINDS SOUTH TO SOUTHEAST OVERNIGHT BECOMING NORTHWEST BEHIND THE LOW PRESSURE. SPEEDS GENERALLY AT OR BELOW 10 KNOTS. KMSP...VFR CIGS AS THE PRECIPITATION MOVES IN...THEN CLOSE TO MVFR DURING THE BEST WINDOW OF PRECIP. PRECIPITATION TYPE PROBLEMATIC AS WE WILL BE ON THE EDGE OF A RAIN/SNOW LINE. WILL NEED TO WATCH THE TEMP TRENDS AS PRECIP MOVES IN AS THERE IS A LOW RISK OF FREEZING RAIN. FOR NOW WILL GO WITH A RAIN AND SNOW MIX. HAVE INDICATED JUST MVFR VSBYS BUT NEED TO WATCH THAT AS WELL. WILL BE BRIEF IF IT DOES GO DOWN TO IFR. MVFR CIGS SHOULD MOVE IN AT OR AFTER 12Z...AND PERSIST THROUGH THE MORNING. THE NEXT SYSTEM TO BRING IN A CHANCE OF RAIN OR SNOW AFTER 00Z FRIDAY. THERE MAY BE A WINDOW OF VFR CONDITIONS FOR THE AFTERNOON. && && .DISCUSSION... SUMMARY...PATTERN IS A BIT MORE ACTIVE OVER THE NEXT SEVERAL DAYS IN TERMS OF CHANCES OF PRECIPITATION THAN IT HAS BEEN IN QUITE SOME TIME. OVERALL...THE OUTLOOK REMAINS WARM SO THE PRECIP EVENTS EXPECTED TONIGHT...THURSDAY NIGHT AND SATURDAY NIGHT WILL LIKELY HAVE SOME LIQUID PRECIPITATION ASSOCIATED WITH EACH OF THEM. NO MAJOR SYSTEMS EXPECTED AND MAXIMUM QPF WITH EACH EVENT SHOULD LARGELY BE BELOW A QUARTER INCH...A COUPLE OUTLIER RUNS OF THE NAM/GEM WOULD SUGGEST HIGHER QPF TOTALS WITH THE THURSDAY NIGHT AND SATURDAY NIGHT SYSTEMS. THE INTERIOR OF CANADA HAS COOLED SINCE THE LAST TIME I WAS ON A FORECAST SHIFT LATE LAST WEEK...BUT STILL NO TRUE ARCTIC AIR ENCROACHING ON THE US CONUS. THE ARCTIC AIR IS STILL BEING CONFINED TO THE HIGHER LATITUDES...LARGELY ABOVE 55-60 DEGREES NORTH. PACIFIC AIR MASSES WILL CONTINUE TO IMPACT THE US THROUGH THE END OF THE YEAR. PROGRESSIVE UPPER FLOW WILL BE FEATURED AS A SERIES OF DISTURBANCES SURGE FROM THE NORTHEASTERN PACIFIC AND INTO THE PACIFIC NORTHWEST. THE SOUTHWARD EXTENT OF THIS UPPER TROUGH SHOULD BE LIMITED BY A RIDGE ACROSS THE SOUTHWEST US. AS A RESULT...THE SWATH OF PRECIPITATION SHOULD NOT EXTEND MUCH FARTHER SOUTH THAN 40 DEGREES NORTH. THIS WILL KEEP MN AND WI UNDER THE GUN FOR A FEW LIGHT PRECIPITATION EVENTS OVER THE COMING DAYS. THE FAST MOVING FLOW ALOFT WILL KEEP UNSETTLED CONDITIONS IN PLACE FOR MUCH OF THE PACIFIC NORTHWEST...NORTHERN ROCKIES AND UPPER MISSISSIPPI VALLEY THROUGH THE WEEKEND. THE FIRST IN A PAIR OF SYSTEMS IS CURRENTLY MOVING OUT OF THE NORTHERN ROCKIES AND INTO THE NORTHERN PLAINS. LIGHT RAIN IS RAPIDLY PUSHING INTO THE EASTERN DAKOTAS LATE THIS AFTERNOON AND THE HRRR TREND IS TAKE THE LIGHT RAIN INTO WESTERN MN BETWEEN 00-03Z. IF THE CURRENT TRENDS HOLD...MOST OF THE PRECIP WILL PUSH OUT OF THE FORECAST AREA BETWEEN 06-09Z...A BIT FASTER THAN THE CURRENT FORECAST INDICATES. ALSO SOME QUESTION WHETHER OR NOT THE MIXED PRECIPITATION WILL REALLY PAN OUT IN PARTS OF CENTRAL/SOUTHERN MN. COOLING WILL BE TOUGH WITH CLOUD COVER AND WEAK WARM AIR ADVECTION. IT MIGHT END UP BEING NEARLY ALL LIGHT RAIN RATHER THAN SNOW OR FREEZING RAIN. IN THE EXTENDED...INCREASINGLY MERIDIONAL FLOW WILL LEAD TO MORE AMPLIFIED TROUGHS ACROSS THE EASTERN PACIFIC THROUGH THE GREAT LAKES WITH RIDGING SANDWICHED IN BETWEEN. MOST OF THE GUIDANCE AGREES ON THIS PATTERN...OUTSIDE THE 00Z GFS WHICH WAS BROAD AND FLAT WITH THE EASTERN TROUGH DESPITE ITS AMPLIFIED RIDGE UPSTREAM. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ CLF/JPR
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1033 AM CST TUE DEC 27 2011 .DISCUSSION... MORNING UPDATE CONCENTRATES ON SKY AND TEMPS. EARLY VIS SHOWED STRATOCU DECK EAST OF THE VALLEY...HOWEVER IT IS QUICKLY BREAKING UP AS EVIDENT FROM WEB CAMS OVER THE BJI AREA. THUS BUMPED UP SKY FROM 15Z TO 21Z AND THEN BEGAN TO SCATTER IT BACK OUT. LIKELY SCENARIO IS THAT CIRRUS WILL ARRIVE BEFORE SCATTERING COMPLETELY OUT. LATEST NAM ISENTROPIC CHARTS AND LOW LEVEL WARM ADVECTION STARTING TO KICK IN AROUND 21Z...THUS NOT SURE WE WILL SEE ANY SNOW OUT WEST IN THE 18Z TO 21Z TIMEFRAME...BUT BY 00Z IT IS A POSSIBILITY. CURRENT POP GRIDS LOOK DECENT ALTHOUGH MAY PULL 18Z TO 21Z POPS AFTER FURTHER ANALYSIS. TEMPS CURRENTLY COLDER THAN PREV FCST ADVERTISED...BUT WITH WARM ADVECTION KICKING IN MID AFTN THINK FCST HIGHS ARE REASONABLE DESPITE CIRRUS. MADE ADJUSTMENTS TO HOURLY TEMPS TO COMPENSATE FOR CURRENT OBS AND A LATER START. && .AVIATION... LOW CLOUDS WITH MVFR/LCLLY IFR/ PTCHY 4SM -SN CONTINUE OVER PORTIONS OF NORTHWEST MINNESOTA. CLOUD DECK APPEARS THIN AND IS MOVING DUE SOUTH AROUND 10 KTS. RUC13 MODEL X-SECT AND SAT/11-3.9/ SUGGEST SHOULD CLEAR TVF AROUND 18Z BUT HOLD IN BJI AREA THROUGH 00Z. WINDS WILL CONTINUE TO DECREASE AND BECOME VRB AROUND 00Z TVF/BJI WITH SFC RIDGE OVER AREA. VFR ALONG AND WEST OF RRV THROUGH 00Z. A BAND OF LIGHT SNOW WITH MVFR CEILINGS IS EXPECTED OVERNIGHT...BUT ADJUSTMENTS IN TIMING ARE LIKELY THROUGH THE DAY. && .PREV DISCUSSION... /ISSUED 356 AM CST TUE DEC 27 2011/ SHORT TERM...TODAY THROUGH THURSDAY NIGHT PRIMARY FORECAST CHALLENGE WILL BE PRECIPITATION CHANCES AND AMOUNTS TONIGHT THROUGH MUCH OF THE WEEK AS A SERIES OF WAVES MOVE ACROSS THE NORTHERN PLAINS IN FAST NORTHWEST FLOW ALOFT. GFS/ECMWF/GEM IN REASONABLE AGREEMENT THROUGH THURSDAY MORNING...DIVERGING SOMEWHAT THEREAFTER. THE NAM IS A BIT OF AN OUTLIER AND WILL NOT BE USED IN THIS FORECAST PACKAGE. COLD FRONT FROM LAST EVENING HAS MOVED WELL SOUTH OF THE FORECAST AREA WITH STRONG COLD AIR ADVECTION AND BREEZY NORTHERLY WINDS IN ITS WAKE. SURFACE TEMPERATURES ACROSS SOUTHERN MANITOBA ARE IN THE LOW SINGLE DIGITS ABOVE ZERO AND THIS COLD AIR WILL CONTINUE TO FILTER TO THE SOUTH THROUGH THE EARLY MORNING HOURS. LOW STRATUS ALONG AND SOUTHEAST OF A LINE FROM JAMESTOWN TO GRAND FORKS TO ROSEAU WILL CONTINUE TO SLIDE SOUTH AND EAST...RESULTING IN MOSTLY SUNNY SKIES BY MID TO LATE MORNING REGION WIDE. NORTH WINDS WILL RELAX THROUGH THE DAY AS THE PRESSURE GRADIENT WEAKENS AND SURFACE HIGH PRESSURE MOVES INTO THE NORTHERN PLAINS. WITH A DRAMATIC CHANGE IN THE AIR MASS...TEMPERATURES TODAY WILL BE 20 TO 30 DEGREES LOWER THAN YESTERDAY/S RECORD HIGHS. FOR TONIGHT...A NARROW BAND OF LIGHT SNOW WILL MOVE FROM WEST TO EAST ACROSS THE FORECAST AREA...COINCIDENT WITH INCREASING MID- LEVEL WARM AIR ADVECTION/CLOUD COVER AND MODEST ISENTROPIC LIFT ON THE 280 K SURFACE. ACCUMULATIONS WILL BE LIGHT...BUT SOME SPOTS MAY RECEIVE UP TO AN INCH OF NEW SNOW BY WEDNESDAY MORNING. ANOTHER WAVE WILL MOVE THROUGH THE REGION WEDNESDAY AND WEDNESDAY NIGHT...BRINGING A BETTER CHANCE OF ACCUMULATING SNOW (1-2 INCHES) ACROSS PORTIONS OF EASTERN ND AND NORTHWEST MN. THE ECMWF AND GEM SURFACE LOW TRACKS ARE A BIT FARTHER SOUTH THAN THE GFS...BUT ALL THREE MODELS SHOW A BAND OF ROUGHLY ONE TENTH OF AN INCH LIQUID QPF BISECTING THE FORECAST AREA FROM NORTHWEST TO SOUTHEAST. ECMWF RUN TO RUN CONSISTENCY IS SLIGHTLY BETTER THAN THE GFS...SO PREFER ITS MORE SOUTHERN SOLUTION...WHICH PLACES THE MOST PRECIPITATION ALONG A RUGBY TO VALLEY CITY TO WAHPETON LINE. DUE TO DIFFERENCES IN TRACK...WILL KEEP POPS IN THE CHANCE CATEGORY FOR NOW. TEMPERATURES WEDNESDAY WILL ONCE AGAIN CLIMB TO WELL ABOVE NORMAL WITH HIGHS APPROACHING 40 DEGREES IN THE SOUTHERN VALLEY...SO INITIAL PRECIPITATION PHASE MAY BE A RAIN/SNOW MIX OR ALL RAIN. MODELS ARE IN POOR AGREEMENT THURSDAY AND THURSDAY NIGHT WITH THE GFS DRY AND THE ECMWF/GEM/NAM BRINGING ANOTHER BAND OF LIGHT SNOW ACROSS THE REGION LATE IN THE DAY. WILL KEEP CHANCE POPS GOING...BUT ADJUSTMENTS WILL BE NEEDED ONCE MODELS COME INTO BETTER AGREEMENT. TEMPERATURES WILL DROP SOME ON THURSDAY...BUT STILL REMAIN ABOVE LATE-DECEMBER NORMALS WITH HIGHS IN THE MID 20S TO MID 30S. LONG TERM...FRIDAY THROUGH MONDAY NIGHT WILL CONTINUE TO KEEP THE 20-30 POPS WE HAVE GOING FOR FRIDAY... AS ALL DETERMINISTIC MODELS ARE IN PRETTY GOOD AGREEMENT ON BREAKING OUT SOME PRECIP AS A WEAK SHORTWAVE MOVES THROUGH THE AREA. A MORE SIGNIFICANT WAVE APPROACHES THE AREA ON SATURDAY... AND THERE IS SOME VARIATION ON HOW FAST THE MODELS BRING THE SYSTEM THROUGH. THE ECMWF CLOSES OFF A LOW AND IS MUCH SLOWER THAN THE GFS AND GEM...WHICH BRING A COLD FRONT THROUGH FAIRLY EARLY ON THE DAY ON SATURDAY. THE ECMWF CONTINUES WITH WARM AIR ADVECTION IN SATURDAY AFTERNOON. ENSEMBLE SPREAD IS PRETTY HIGH WITH THE SYSTEM...BUT THE GFS ENSEMBLE MEAN HAS SOME WARMER TEMPS IN THE SOUTHERN CWA LIKE THE OPERATIONAL ECMWF. BUMPED UP TEMPS A BIT IN THE SOUTHERN COUNTIES...AND INCLUDED A MIX OF RAIN AND SNOW MENTION. MODEL CONSENSUS GOES FURTHER DOWNHILL ON DAYS 6 AND 7...WITH THE GFS AND GEM SETTING UP NEAR ZONAL FLOW AND THE ECMWF BECOMING VERY MERIDIONAL AS THE UPPER TROUGH DIGS INTO THE GREAT LAKES. WENT WITH THE COMPROMISE ALLBLEND AND WILL CONTINUE TO KEEP SOME LOW POPS IN THE NORTH AND EAST FOR SUNDAY IN CASE THE SLOWER ECMWF VERIFIES...BUT KEPT TEMPS WARMER THAN THE NORTHERLY FLOW OF THE ECMWF WOULD INDICATE. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ SPEICHER/EWENS
AREA FORECAST DISCUSSION...UPDATED
NWS NASHVILLE TN
614 AM CST TUE DEC 27 2011 .UPDATE... MAIN AREA OF MODERATE RAINFALL HAS MOVED NORTHEAST OF MID STATE THIS MORNING. SHORT RANGE/HRRR MODELS ALSO SHOWING THAT SHWRS WILL CONTINUE TO OCCUR...NOT STEADILY...BUT AT IRREGULAR INTERVALS...AS SFC/UPPER LEVEL TROUGH MOVES TO THE NE THRU THE MORNING HRS. THUS... WILL UPDATE THE SUITE OF FORECAST PRODUCTS TO REFLECT INTERMITTENT SHWRS ALL AREAS THRU THE MORNING HRS. && .PREV DISCUSSION.../ISSUED 523 AM CST TUE DEC 27 2011/ UPDATE...FOR AVIATION. AVIATION... 12Z TAFS...LOW PRESSURE NEAR CKV WILL DEEPEN AS IT MOVES NORTHEAST ACROSS KY TODAY. INCREASING PRESSURE GRADIENT WILL CAUSE GUSTY WINDS TO 25KT OR SO TO DEVELOP...FROM THE SW THIS MORNING...THEN BECOMING WNW. SCATTERED SHOWERS WILL OCCUR MAINLY THIS MORNING WITH SOME MVFR VSBYS. CIGS WILL BE MAINLY IFR THROUGH THE MORNING. BNA WILL IMPROVE TO MVFR IN THE AFTERNOON AND VFR TONIGHT. CSV WILL HOVER FROM IFR TO MVFR THROUGH THE PERIOD. 13 PREV DISCUSSION... /ISSUED 333 AM CST TUE DEC 27 2011/ DISCUSSION... FORECAST REASONING WILL LEAN TOWARD A CONSENSUS MODEL SOLUTION COMPROMISE FOR THE FORECAST PERIOD UNLESS OTHERWISE NOTED. MAIN FORECAST QUANDARIES...ACTUAL TIMING OF RAINFALL ENDING W TO E AND STRENGTH OF WINDS TODAY...POSSIBLE RAIN/SNOW MIX PLATEAU THIS EVENING...TEMPS...AND OVERALL FORECAST EARLY NEXT WEEK. AS FOR TODAY...AS OF 09Z...WIDE SWATH OF LIGHT TO MODERATE SHWRS MOVING GENERALLY S TO N ACROSS MID STATE ACROSS LOCATIONS GENERALLY ALONG AND E OF I-65. SOME BREAKS IN RAINFALL NOTED W OF THIS AREA... BUT SHWRS DEVELOPING IN VICINITY OF UPPER LEVEL LOW ACROSS W TN AND ERN AK. ALL OF THIS AS SFC LOW CONTINUES TO MOVE ACROSS W TN...WITH UPPER LEVEL TROUGH BEGINNING TO MOVE INTO FAR WRN PORTIONS OF THE STATE. WILL BE MAKING FINAL DECISION AT PRESS TIME...BUT AM LEANING TOWARD DEF SHWRS GENERALLY E OF I-65 TO NUMEROUS SHWRS W...TRANSITIONING TO NUMEROUS TO SCATTERED LIGHT SHWRS ALL LOCATIONS EXPECT THOSE CLOSE TO AND ACROSS THE CUMBERLAND PLATEAU REGION DURING THE LATER MORNING HRS. THIS AFTERNOON THE MID STATE SHOULD EXPERIENCE AREAS ACROSS WRN MIDDLE TN FINALLY BECOME DRY NEAR AND JUST EAST OF THE TN RIVER VALLEY REGION...WITH ISO/SCT LIGHT SHWRS ACROSS THE REMAINDER OF THE MID STATE DURING THE AFTERNOON HRS. THIS REASONING BASED ON THE FACT THAT THE SFC LOW AND UPPER LEVEL TROUGH WILL CONTINUE TO MOVE NEWD OVER TIME WITH CLDY SKIES ACROSS MOST LOCATIONS THRU THE AFTERNOON HRS. HRRR MODEL HINTING AT THE POTENTIAL FOR A RAIN/SNOW MIX ACROSS FAR NW PORTIONS OF THE MID STATE BY THE EARLY AFTERNOON HRS...BUT WITH TEMPS EXPECTED TO REMAIN VERY CLOSE TO CURRENT TEMPS IN THE LOWER 40S THRU THE AFTERNOON HRS...WILL NOT MENTION IN THE SUITE OF FORECAST PRODUCTS AS OF THIS TIME. DO NOT EXPECT OTHER LOCATIONS ACROSS THE MID STATE TO DEVIATE MUCH FROM CURRENT TEMPS BEING EXPERIENCED. AS THIS SYSTEM MOVES NEWD...EXPECT SOME MIXING DOWN OF 30 TO 40 MPH 925MB WINDS TO THE SFC DURING THE AFTERNOON HRS. DO NOT EXPECT ANY LOCATION ACROSS THE MID STATE TO REACH WIND ADVISORY CRITERIA AS OF THIS TIME...BUT WOULD NOT BE SURPRISED THAT SOME LOCATIONS EXPERIENCE GUSTS OF 25 TO 30 MPH LATER THIS AFTERNOON. AS FOR TONIGHT...THERE MIGHT BE A SLIGHT CHANCE OF A RAIN/SNOW MIXTURE ACROSS NRN PORTIONS OF THE CUMBERLAND PLATEAU DURING THE EARLY EVENING HRS AS MOISTURE ASSOCIATED WITH UPPER LEVEL TROUGH MOVES ACROSS THIS PART OF THE MID STATE AND WITH TEMPS EXPECTED TO FALL INTO THE UPPER TO MID 30S. HOWEVER...AS OF THIS TIME...NO ACCUMULATION IS EXPECTED. OTHERWISE...LOOK FOR A SLOW DECREASE IN CLOUDINESS W TO E ACROSS THE MID STATE...WITH DRY CONDITIONS...AND LOWS NEAR NORMAL VALUES FOR THIS TIME OF YEAR...AROUND 30...UPPER 20S PLATEAU. AS FOR WED...A WEAK SHORTWAVE PASSAGE IS EXPECTED ACROSS THE SRN OHIO VALLEY AND PORTIONS OF KY DURING THE AFTERNOON HRS...WHICH MIGHT BRING SOME ADDITIONAL CLOUDINESS TO LOCATIONS APPROACHING THE TN/KY BORDER. HOWEVER...AT THIS TIME...WILL GO WITH PTCDLY SKIES ACROSS THE ENTIRE MID STATE...WITH AFTERNOON HIGH TEMPS GETTING BACK CLOSE TO CLIMATOLOGICAL NORMS...WITH HIGHS IN THE MID 40S N TO UPPER 40S S...LOW 40S PLATEAU. AS FOR WED NIGHT...SKIES SHOULD EVENTUALLY BECOME MOCLR BY LATE WED NIGHT...WITH LOWS AGAIN IN THE LOWER 30S...UPPER 20S PLATEAU. AS FOR THU...AS HIGH SHIFTS EWD...AND MORE OF A SLY SFC FLOW DEVELOPS ACROSS THE MID STATE...HIGHS SHOULD WARM UP INTO THE LOWER TO MID 50S... WITH PTCLDY SKIES AND DRY CONDITIONS. AS FOR THE REST OF THE FORECAST PERIOD...WILL KEEP IT DRY THRU NEW YEARS DAY...WHEN THE NEXT CHANCE OF RAINFALL ACROSS THE MID STATE WILL OCCUR AS ANOTHER COLD FRONT IS EXPECTED TO MOVE ACROSS THE MID STATE. INTO THE FIRST HALF OF NEXT WEEK THOUGH...SIGNIFICANT MODEL DIFFERENCES ARE OCCURRING. THE GFS BEING THE DRIER AND WARMER SOLUTION AND THE EURO BEING THE COLDER AND WETTER SOLUTION. AM GOING TO PLAY IT MIDDLE OF THE ROAD HERE...AND GO WITH A DRY FORECAST...A LEAN MORE TOWARD THE GFS...AS I AM A LITTLE WEARY OF THE VERY PROGRESSIVE AND DEEP UPPER LEVEL LOW AND TROUGH SOLUTION THAT THE EURO IS ADVERTISING ACROSS THE MID SOUTH NEXT TUE INTO WED. THRU THIS PERIOD...AFTERNOON HIGH TEMPS WILL MAINLY BE IN THE 50S...WITH OVERNIGHT LOWS...EXPECT FOR SAT NIGHT WHICH WILL BE IN THE MID 40S...MAINLY IN THE 30S. 31 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 31
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
523 AM CST TUE DEC 27 2011 .UPDATE...FOR AVIATION. && .AVIATION... 12Z TAFS...LOW PRESSURE NEAR CKV WILL DEEPEN AS IT MOVES NORTHEAST ACROSS KY TODAY. INCREASING PRESSURE GRADIENT WILL CAUSE GUSTY WINDS TO 25KT OR SO TO DEVELOP...FROM THE SW THIS MORNING...THEN BECOMING WNW. SCATTERED SHOWERS WILL OCCUR MAINLY THIS MORNING WITH SOME MVFR VSBYS. CIGS WILL BE MAINLY IFR THROUGH THE MORNING. BNA WILL IMPROVE TO MVFR IN THE AFTERNOON AND VFR TONIGHT. CSV WILL HOVER FROM IFR TO MVFR THROUGH THE PERIOD. 13 && .PREV DISCUSSION... /ISSUED 333 AM CST TUE DEC 27 2011/ DISCUSSION... FORECAST REASONING WILL LEAN TOWARD A CONSENSUS MODEL SOLUTION COMPROMISE FOR THE FORECAST PERIOD UNLESS OTHERWISE NOTED. MAIN FORECAST QUANDARIES...ACTUAL TIMING OF RAINFALL ENDING W TO E AND STRENGTH OF WINDS TODAY...POSSIBLE RAIN/SNOW MIX PLATEAU THIS EVENING...TEMPS...AND OVERALL FORECAST EARLY NEXT WEEK. AS FOR TODAY...AS OF 09Z...WIDE SWATH OF LIGHT TO MODERATE SHWRS MOVING GENERALLY S TO N ACROSS MID STATE ACROSS LOCATIONS GENERALLY ALONG AND E OF I-65. SOME BREAKS IN RAINFALL NOTED W OF THIS AREA... BUT SHWRS DEVELOPING IN VICINITY OF UPPER LEVEL LOW ACROSS W TN AND ERN AK. ALL OF THIS AS SFC LOW CONTINUES TO MOVE ACROSS W TN...WITH UPPER LEVEL TROUGH BEGINNING TO MOVE INTO FAR WRN PORTIONS OF THE STATE. WILL BE MAKING FINAL DECISION AT PRESS TIME...BUT AM LEANING TOWARD DEF SHWRS GENERALLY E OF I-65 TO NUMEROUS SHWRS W...TRANSITIONING TO NUMEROUS TO SCATTERED LIGHT SHWRS ALL LOCATIONS EXPECT THOSE CLOSE TO AND ACROSS THE CUMBERLAND PLATEAU REGION DURING THE LATER MORNING HRS. THIS AFTERNOON THE MID STATE SHOULD EXPERIENCE AREAS ACROSS WRN MIDDLE TN FINALLY BECOME DRY NEAR AND JUST EAST OF THE TN RIVER VALLEY REGION...WITH ISO/SCT LIGHT SHWRS ACROSS THE REMAINDER OF THE MID STATE DURING THE AFTERNOON HRS. THIS REASONING BASED ON THE FACT THAT THE SFC LOW AND UPPER LEVEL TROUGH WILL CONTINUE TO MOVE NEWD OVER TIME WITH CLDY SKIES ACROSS MOST LOCATIONS THRU THE AFTERNOON HRS. HRRR MODEL HINTING AT THE POTENTIAL FOR A RAIN/SNOW MIX ACROSS FAR NW PORTIONS OF THE MID STATE BY THE EARLY AFTERNOON HRS...BUT WITH TEMPS EXPECTED TO REMAIN VERY CLOSE TO CURRENT TEMPS IN THE LOWER 40S THRU THE AFTERNOON HRS...WILL NOT MENTION IN THE SUITE OF FORECAST PRODUCTS AS OF THIS TIME. DO NOT EXPECT OTHER LOCATIONS ACROSS THE MID STATE TO DEVIATE MUCH FROM CURRENT TEMPS BEING EXPERIENCED. AS THIS SYSTEM MOVES NEWD...EXPECT SOME MIXING DOWN OF 30 TO 40 MPH 925MB WINDS TO THE SFC DURING THE AFTERNOON HRS. DO NOT EXPECT ANY LOCATION ACROSS THE MID STATE TO REACH WIND ADVISORY CRITERIA AS OF THIS TIME...BUT WOULD NOT BE SURPRISED THAT SOME LOCATIONS EXPERIENCE GUSTS OF 25 TO 30 MPH LATER THIS AFTERNOON. AS FOR TONIGHT...THERE MIGHT BE A SLIGHT CHANCE OF A RAIN/SNOW MIXTURE ACROSS NRN PORTIONS OF THE CUMBERLAND PLATEAU DURING THE EARLY EVENING HRS AS MOISTURE ASSOCIATED WITH UPPER LEVEL TROUGH MOVES ACROSS THIS PART OF THE MID STATE AND WITH TEMPS EXPECTED TO FALL INTO THE UPPER TO MID 30S. HOWEVER...AS OF THIS TIME...NO ACCUMULATION IS EXPECTED. OTHERWISE...LOOK FOR A SLOW DECREASE IN CLOUDINESS W TO E ACROSS THE MID STATE...WITH DRY CONDITIONS...AND LOWS NEAR NORMAL VALUES FOR THIS TIME OF YEAR...AROUND 30...UPPER 20S PLATEAU. AS FOR WED...A WEAK SHORTWAVE PASSAGE IS EXPECTED ACROSS THE SRN OHIO VALLEY AND PORTIONS OF KY DURING THE AFTERNOON HRS...WHICH MIGHT BRING SOME ADDITIONAL CLOUDINESS TO LOCATIONS APPROACHING THE TN/KY BORDER. HOWEVER...AT THIS TIME...WILL GO WITH PTCDLY SKIES ACROSS THE ENTIRE MID STATE...WITH AFTERNOON HIGH TEMPS GETTING BACK CLOSE TO CLIMATOLOGICAL NORMS...WITH HIGHS IN THE MID 40S N TO UPPER 40S S...LOW 40S PLATEAU. AS FOR WED NIGHT...SKIES SHOULD EVENTUALLY BECOME MOCLR BY LATE WED NIGHT...WITH LOWS AGAIN IN THE LOWER 30S...UPPER 20S PLATEAU. AS FOR THU...AS HIGH SHIFTS EWD...AND MORE OF A SLY SFC FLOW DEVELOPS ACROSS THE MID STATE...HIGHS SHOULD WARM UP INTO THE LOWER TO MID 50S... WITH PTCLDY SKIES AND DRY CONDITIONS. AS FOR THE REST OF THE FORECAST PERIOD...WILL KEEP IT DRY THRU NEW YEARS DAY...WHEN THE NEXT CHANCE OF RAINFALL ACROSS THE MID STATE WILL OCCUR AS ANOTHER COLD FRONT IS EXPECTED TO MOVE ACROSS THE MID STATE. INTO THE FIRST HALF OF NEXT WEEK THOUGH...SIGNIFICANT MODEL DIFFERENCES ARE OCCURRING. THE GFS BEING THE DRIER AND WARMER SOLUTION AND THE EURO BEING THE COLDER AND WETTER SOLUTION. AM GOING TO PLAY IT MIDDLE OF THE ROAD HERE...AND GO WITH A DRY FORECAST...A LEAN MORE TOWARD THE GFS...AS I AM A LITTLE WEARY OF THE VERY PROGRESSIVE AND DEEP UPPER LEVEL LOW AND TROUGH SOLUTION THAT THE EURO IS ADVERTISING ACROSS THE MID SOUTH NEXT TUE INTO WED. THRU THIS PERIOD...AFTERNOON HIGH TEMPS WILL MAINLY BE IN THE 50S...WITH OVERNIGHT LOWS...EXPECT FOR SAT NIGHT WHICH WILL BE IN THE MID 40S...MAINLY IN THE 30S. 31 && .OHX WATCHES/WARNINGS/ADVISORIES...NONE. && $$
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)

AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1132 AM CST TUE DEC 27 2011 .SHORT TERM...TODAY THROUGH THURSDAY NIGHT 305 AM CST TUE DEC 27 2011 MAIN FORECAST CONCERN IS ON LOW PRECIPITATION CHANCES THROUGHOUT THE SHORT TERM PERIOD. CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A SHORTWAVE TROUGH OVER BRITISH COLUMBIA...WEAK RIDGING OVER THE SOUTHWEST U.S. INTO ALBERTA AND SASKATCHEWAN...AN UPPER TROUGH OVER MINNESOTA AND AN UPPER LOW OVER NORTHERN MISSISSIPPI. THE UPPER TROUGH IS GRADUALLY BRINGING COLDER AIR INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION...NOTED BY 850MB TEMPS THAT FELL BETWEEN 12Z YESTERDAY AND 00Z TODAY FROM 4C TO 1C AT MPX...AND 6 TO -2C AT BIS. MORE COLD AIR LURKS FARTHER UPSTREAM WITH -12C REPORTED AT THE PAS MANITOBA. MID TO UPPER LEVEL DYNAMIC LIFT WITH THE TROUGH IS FAIRLY WEAK AND MOSTLY OFF TO THE EAST OVER LAKE MICHIGAN...PER QG APPEARANCE FROM THE RUC/ECMWF. THIS LIFT IS WHAT HELPED PRODUCE THE RAIN/SLEET/SNOW LAST EVENING. BIGGER ISSUE WITH THE UPPER TROUGH IS ACTUALLY THE SUBSIDENCE AND THE COLD ADVECTION...WHICH IS HELPING TO PRODUCE 15-20 KT SURFACE SUSTAINED WINDS AND GUSTS TO 30 KT ACROSS MUCH OF MINNESOTA. THESE ARE OCCURRING IN THE WAKE OF TWO COLD FRONTS: THE FIRST SITUATED NORTH-SOUTH OVER CENTRAL WISCONSIN AND THE SECOND ALIGNED WEST EAST FROM ABERDEEN SOUTH DAKOTA INTO UPPER MICHIGAN. A LARGE AMOUNT OF STRATUS EXISTS BEHIND THESE FRONTS...WITH THE LOWEST CEILINGS BEHIND THE SECONDARY FRONT WHERE A GREATER SURGE OF COLD AIR ADVECTION IS HELPING TO UNDERCUT LOW LEVEL MOISTURE. A FEW FLURRIES ALSO OCCURRING FROM THE STRATUS. TODAY AND TONIGHT...MODELS PROG THE UPPER TROUGH OVER MINNESOTA TO MOVE RAPIDLY TO THE EAST...IN RESPONSE TO FAST FLOW COMING OFF THE PACIFIC. BY MIDNIGHT TONIGHT...THE UPSTREAM WEAK RIDGING SHOULD HAVE MOVED INTO THE FORECAST AREA. THIS SITUATION MEANS THAT THE CURRENT STRATUS AND STRONGER WINDS MOVING INTO THE FORECAST AREA FROM MINNESOTA WILL NOT STAY AROUND LONG. IN FACT...GOOD MODEL AGREEMENT EXISTS THAT SKIES SHOULD CLEAR OUT ACROSS MINNESOTA AND IOWA BETWEEN 18-21Z TODAY. ON THE OTHER HAND...OVER WISCONSIN...THERE ARE SUGGESTIONS BY THE 27.00Z NAM/27.03Z RUC THAT THE STRATUS MAY LINGER THROUGH THE EVENING BEFORE DISSIPATING AFTER MIDNIGHT (PER 925MB RH DATA). THIS CERTAINLY SEEMS PLAUSIBLE...SINCE STRATUS TYPICALLY LINGERS LONGER THAN ONE WOULD EXPECT THIS TIME OF YEAR. ALSO...THERE SHOULD BE A GOOD TRANSPORT OF MOISTURE OFF LAKE SUPERIOR GIVEN COLDER AIR FLOWING SOUTH. THEREFORE...HAVE RAISED SKY COVER VALUES OVER WISCONSIN FOR THIS EVENING. REGARDING PRECIP CHANCES WITH THE STRATUS...ANY LIFT IS VERY WEAK...ASSOCIATED WITH LOW LEVEL FRONTOGENESIS. GIVEN OVERALL LACK OF PRECIPITATION RIGHT NOW ON RADAR...ONLY WENT WITH FLURRIES THIS MORNING. DRYING TREND SHOWING UP NOW IN THE HRRR RUNS WOULD AGREE WITH THIS AS WELL. AFTER THAT... SUBSIDENCE TAKING HOLD SHOULD SHUT OFF ANY PRECIPITATION ACTION. LOOKING AHEAD TO AFTER MIDNIGHT TONIGHT...SHORTWAVE TROUGH OVER BRITISH COLUMBIA ALONG WITH A WEAKER SHORTWAVE CURRENTLY SEEN OVER IDAHO ARE FORECAST TO BEGIN TO DROP DOWN INTO MINNESOTA AROUND 12Z TUESDAY. WARM ADVECTION AHEAD OF THESE SHOULD RESULT IN A MID CLOUD DECK OF STRATUS...WHILE ANY PRECIPITATION STAYS NORTHWEST OF THE FORECAST AREA. REGARDING TEMPERATURES...WITH COLD ADVECTION OCCURRING TODAY NOTED BY 850MB TEMPS FALLING TO -5 TO -8C BY 18Z...ANTICIPATING GENERALLY STEADY OR FALLING TEMPERATURES. TONIGHT IS A LITTLE TRICKY WITH STRATUS OVER WISCONSIN AND THEN CLOUDS COMING IN AFTER MIDNIGHT EVERYWHERE. FOR NOW HAVE FOLLOWED A BLEND OF GUIDANCE FOR LOWS. WEDNESDAY AND WEDNESDAY NIGHT...SHORTWAVE OVER MINNESOTA AT 12Z WEDNESDAY IS FORECAST TO SHIFT EAST FAIRLY QUICKLY...REACHING LOWER MICHIGAN BY 00Z THURSDAY. BIGGEST CONCERN WITH THIS SHORTWAVE IS POTENTIAL FOR SOME WARM ADVECTION LIGHT SNOW SKIRTING TAYLOR AND CLARK COUNTIES. THE 00Z NAM/26.21Z SREF SUGGEST THIS IS POSSIBLE... WHEREAS THE 27.00Z GFS/26.12Z ECMWF ARE DRY. GIVEN THE WAY RECENT SYSTEMS HAVE GONE...WITH LIGHT PRECIPITATION HAPPENING DESPITE PRESENCE OF LOW LEVEL DRY AIR...FEEL COMPELLED TO AT LEAST PLACE A 20 PERCENT CHANCE IN TAYLOR AND CLARK COUNTIES. ELSEWHERE...A DECREASING CLOUD TREND SHOULD OCCUR WITH TEMPERATURES CLIMBING INTO THE 30S. COULD SEE READINGS PUSH 40 IN FAR WESTERN AREAS. FOR WEDNESDAY NIGHT...ATTENTION RE-FOCUSES TO THE NORTHWEST WHERE MODELS SHOW A DECENT SHORTWAVE MOVING THROUGH A FAST WEST-NORTHWEST UPPER LEVEL FLOW. AT 00Z...MODELS SUGGEST IT IS EITHER OVER EASTERN MONTANA OR SOUTHEAST SASKATCHEWAN...THEN IT MARCHES SOUTHEAST INTO THE FORECAST AREA AROUND 12Z THURSDAY. AS FAR AS WHERE IN THE FORECAST AREA...THIS VARIES GREATLY...SO FOR NOW HAVE TAKEN A BLEND APPROACH GIVEN THE FAST FLOW. AS THE SHORTWAVE APPROACHES...SHOULD SEE MID AND HIGH CLOUDS DEVELOP IN RESPONSE TO WARM ADVECTION AND DPVA FORCING. LIGHT PRECIPITATION COULD EVEN START BREAKING OUT IN NORTHWESTERN PORTIONS OF THE AREA IN THE EVENING. AFTER MIDNIGHT... ANTICIPATING SOME LIGHT PRECIPITATION EVERYWHERE. PRECIPITATION CHANCES REMAIN IN THE 20 TO 30 RANGE...HOWEVER...DUE TO THE LARGE SPREAD IN TRACK OF THE SHORTWAVE. ENVISION CHANCES NEEDING A BUMP UP IN LATER FORECASTS...BUT WHERE IS THE QUESTION. WITH THE CLOUDS MOVING IN...NOT ANTICIPATING AS MUCH OF A TEMPERATURE FALL AS TONIGHT. GENERALLY FOLLOWED A BLEND OF GUIDANCE FOR LOWS. THURSDAY AND THURSDAY NIGHT...SIMILAR TO THE PAST FEW DAYS...THE PARADE OF SHORTWAVES FROM THE PACIFIC CONTINUE TO COME THROUGH THE FAST FLOW. SHORTWAVE THAT IS NEAR/OVER THE AREA AT 12Z THURSDAY IS PROGGED TO REACH LOWER MICHIGAN BY 00Z...WHILE ANOTHER SHORTWAVE MOVES INTO THE DAKOTAS. SHOULD SEE THE PRECIPITATION DIMINISH FOR A TIME THURSDAY...ESPECIALLY IN THE AFTERNOON NORTH OF I-90 AS THAT AREA GETS INTO THE SUBSIDENCE BEHIND THE MORNING SHORTWAVE. DURING THE AFTERNOON...PRECIPITATION IS POSSIBLE SOUTH OF I-90 AS WARM ADVECTION OCCURS DOWNSTREAM OF THE SHORTWAVE ENTERING THE DAKOTAS. WITH UNCERTAINTY ON THE PLACEMENT OF THE SHORTWAVE NEAR/OVER THE AREA AT 12Z THURSDAY...ALONG WITH SUGGESTIONS OF LOW LEVEL DRY AIR TO OVERCOME IN SOUNDINGS...HAVE KEPT PRECIPITATION CHANCES BETWEEN 20 AND 30. A LOT OF UNCERTAINTY EXISTS WITH THIS DAKOTAS SHORTWAVE HEADING INTO THURSDAY NIGHT...WHERE THE 27.00Z ECMWF/UKMET DROP IT DOWN INTO MISSOURI WHEREAS THE 27.00Z GFS CROSSES IOWA AND THE 27.00Z NAM CROSSES THE FORECAST AREA. FEELING IS THE SOUTHERN SOLUTIONS MAY HAVE A BETTER CHANCE OF VERIFYING...DUE TO THE USUAL BETTER PREDICTABILITY OF THE ECMWF...BUT NOT COMPLETELY SURE GIVEN THE FAST FLOW. THEREFORE...20 TO 30 PERCENT CHANCES CONTINUE FOR THURSDAY NIGHT. WITH SO MUCH UNCERTAINTY ON THE TRACKS OF THESE SHORTWAVES...TEMPERATURE FORECASTS ARE PROBLEMATIC. CERTAINLY POTENTIAL EXISTS ON THURSDAY FOR AT LEAST THE SOUTHERN PORTION OF THE AREA TO HIT 40 OR HIGHER...ESPECIALLY IF THE SHORTWAVE THEN TRACKS FARTHER NORTH. CLOUDS THURSDAY NIGHT SHOULD HOLD TEMPERATURES UP IN THE 20S TO LOW 30S...COLDEST IN TAYLOR AND CLARK COUNTIES WHERE COOLER AIR SINKS SOUTH BEHIND THE SHORTWAVE MOSTLY SUGGESTED TO TRACK NEAR OR SOUTH OF THE AREA. .LONG TERM...FRIDAY THROUGH MONDAY NIGHT 305 AM CST TUE DEC 27 2011 27.00Z MODEL CYCLE CONSISTING OF THE ECMWF/GFS/CANADIAN AND GFS ENSEMBLES STILL PRESENT PLENTY OF UNCERTAINTY WITH REGARDS TO THE UPPER LEVEL PATTERN THROUGHOUT THE LONG TERM PERIOD...THOUGH THERE ARE SOME FEATURES THAT CAN BE LATCHED ONTO. THE FIRST IS A FAIRLY POTENT SHORTWAVE TROUGH POISED TO COME INTO THE PACIFIC NORTHWEST ON FRIDAY...RESULTING IN BUILDING RIDGING DOWNSTREAM TOWARDS THE FORECAST AREA. THIS RIDGING LOOKS TO BUILD INTO THE AREA FRIDAY NIGHT...BRINGING IN A SURGE OF DOWNSLOPED PACIFIC AIR. TIMING THE PACIFIC NORTHWEST SHORTWAVE TROUGH AND INTENSITY WILL BE CRITICAL IN DETERMINING HOW WARM NEW YEARS EVE IS. LOOKS LIKE THERE SHOULD BE SOME WARM ADVECTION PRECIPITATION DOWNSTREAM INTO THE AREA FRIDAY/FRIDAY NIGHT...BUT THIS MOSTLY LIFTS NORTH ON NEW YEARS EVE. THE 26.12Z/27.00Z ECMWF RUNS ARE BY FAR THE MOST AMPLIFIED... RESULTING IN A SLOWER COLD FRONTAL PASSAGE AND HIGH TEMPERATURES SATURDAY FROM THE 40S INTO THE LOW 50S. FOR NOW HAVE TAKEN A 30 DAY BIAS CORRECTION OF THE CONSENSUS OF ALL GUIDANCE...WHICH RESULTS IN HIGHS MOSTLY IN THE 40S. CERTAINLY POTENTIAL EXISTS FOR WARMER READINGS GIVEN LACK OF SNOW COVER STILL ANTICIPATED. COLDER AIR WILL MOVE INTO THE AREA FOR NEW YEARS DAY AS THE UPPER TROUGH MOVES IN...BUT HOW MUCH DEPENDS ON THE PROGRESSIVE NATURE OF THE UPPER TROUGH. THE MORE AMPLIFIED ECMWF BASICALLY TURNS THE TROUGH INTO A LONGWAVE TROUGH...ALLOWING FOR AIR OF MORE ARCTIC ORIGIN TO FLOW SOUTH INTO THE AREA FOR NEW YEARS DAY AND MONDAY. ON THE OTHER HAND...THE 27.00Z GFS/CANADIAN DEPICT MUCH MORE PROGRESSION... RESULTING IN A CONTINUED FEED OF PACIFIC AIR AND WARMER. GIVEN SO MUCH UNCERTAINTY...A CONSENSUS OF GUIDANCE WAS FOLLOWED FOR NEW YEARS DAY THROUGH MONDAY NIGHT. IN EITHER MODEL CAMP SCENARIO...IT LOOKS LIKE LITTLE IF ANY PRECIPITATION WILL OCCUR. && .AVIATION...THROUGH 18Z WEDNESDAY 1131 AM CST TUE DEC 27 2011 WINDS WILL GRADUALLY DIMINISH THIS AFTERNOON AS HIGH PRESSURE BUILDS INTO THE REGION. LOOK FOR NORTHEAST WINDS AT 15 TO 20 KTS GUSTING TO AROUND 27 KTS EARLY THIS AFTERNOON...THEN DECREASING INTO THE 10 TO 13 KT RANGE AS THE HIGH EDGES INTO THE AREA. MVFR CEILINGS WILL IMPROVE TO VFR THIS AFTERNOON...WITH A FEW LINGERING CUMULUS IN THE AREA...WITH CLOUD BASES AROUND 2 KFT. A SHORTWAVE TROUGH IS EXPECTED TO MOVE ACROSS THE DAKOTAS AND INTO THE AREA TONIGHT...SPREADING MID LEVEL CLOUDS ACROSS THE AREA. LOOK FOR CLOUD BASES IN THE 5 TO 8 KFT RANGE AS THE TROUGH MOVES THROUGH. VFR CONDITIONS WILL PERSIST OVERNIGHT INTO WEDNESDAY MORNING. LIGHT AND VARIABLE WINDS OVERNIGHT WILL BECOME SOUTH LATE WEDNESDAY MORNING IN THE 10 TO 15 KT RANGE. && .ARX WATCHES/WARNINGS/ADVISORIES... 305 AM CST TUE DEC 27 2011 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
521 AM CST TUE DEC 27 2011 .SHORT TERM...TODAY THROUGH THURSDAY NIGHT 305 AM CST TUE DEC 27 2011 MAIN FORECAST CONCERN IS ON LOW PRECIPITATION CHANCES THROUGHOUT THE SHORT TERM PERIOD. CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A SHORTWAVE TROUGH OVER BRITISH COLUMBIA...WEAK RIDGING OVER THE SOUTHWEST U.S. INTO ALBERTA AND SASKATCHEWAN...AN UPPER TROUGH OVER MINNESOTA AND AN UPPER LOW OVER NORTHERN MISSISSIPPI. THE UPPER TROUGH IS GRADUALLY BRINGING COLDER AIR INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION...NOTED BY 850MB TEMPS THAT FELL BETWEEN 12Z YESTERDAY AND 00Z TODAY FROM 4C TO 1C AT MPX...AND 6 TO -2C AT BIS. MORE COLD AIR LURKS FARTHER UPSTREAM WITH -12C REPORTED AT THE PAS MANITOBA. MID TO UPPER LEVEL DYNAMIC LIFT WITH THE TROUGH IS FAIRLY WEAK AND MOSTLY OFF TO THE EAST OVER LAKE MICHIGAN...PER QG APPEARANCE FROM THE RUC/ECMWF. THIS LIFT IS WHAT HELPED PRODUCE THE RAIN/SLEET/SNOW LAST EVENING. BIGGER ISSUE WITH THE UPPER TROUGH IS ACTUALLY THE SUBSIDENCE AND THE COLD ADVECTION...WHICH IS HELPING TO PRODUCE 15-20 KT SURFACE SUSTAINED WINDS AND GUSTS TO 30 KT ACROSS MUCH OF MINNESOTA. THESE ARE OCCURRING IN THE WAKE OF TWO COLD FRONTS: THE FIRST SITUATED NORTH-SOUTH OVER CENTRAL WISCONSIN AND THE SECOND ALIGNED WEST EAST FROM ABERDEEN SOUTH DAKOTA INTO UPPER MICHIGAN. A LARGE AMOUNT OF STRATUS EXISTS BEHIND THESE FRONTS...WITH THE LOWEST CEILINGS BEHIND THE SECONDARY FRONT WHERE A GREATER SURGE OF COLD AIR ADVECTION IS HELPING TO UNDERCUT LOW LEVEL MOISTURE. A FEW FLURRIES ALSO OCCURRING FROM THE STRATUS. TODAY AND TONIGHT...MODELS PROG THE UPPER TROUGH OVER MINNESOTA TO MOVE RAPIDLY TO THE EAST...IN RESPONSE TO FAST FLOW COMING OFF THE PACIFIC. BY MIDNIGHT TONIGHT...THE UPSTREAM WEAK RIDGING SHOULD HAVE MOVED INTO THE FORECAST AREA. THIS SITUATION MEANS THAT THE CURRENT STRATUS AND STRONGER WINDS MOVING INTO THE FORECAST AREA FROM MINNESOTA WILL NOT STAY AROUND LONG. IN FACT...GOOD MODEL AGREEMENT EXISTS THAT SKIES SHOULD CLEAR OUT ACROSS MINNESOTA AND IOWA BETWEEN 18-21Z TODAY. ON THE OTHER HAND...OVER WISCONSIN...THERE ARE SUGGESTIONS BY THE 27.00Z NAM/27.03Z RUC THAT THE STRATUS MAY LINGER THROUGH THE EVENING BEFORE DISSIPATING AFTER MIDNIGHT (PER 925MB RH DATA). THIS CERTAINLY SEEMS PLAUSIBLE...SINCE STRATUS TYPICALLY LINGERS LONGER THAN ONE WOULD EXPECT THIS TIME OF YEAR. ALSO...THERE SHOULD BE A GOOD TRANSPORT OF MOISTURE OFF LAKE SUPERIOR GIVEN COLDER AIR FLOWING SOUTH. THEREFORE...HAVE RAISED SKY COVER VALUES OVER WISCONSIN FOR THIS EVENING. REGARDING PRECIP CHANCES WITH THE STRATUS...ANY LIFT IS VERY WEAK...ASSOCIATED WITH LOW LEVEL FRONTOGENESIS. GIVEN OVERALL LACK OF PRECIPITATION RIGHT NOW ON RADAR...ONLY WENT WITH FLURRIES THIS MORNING. DRYING TREND SHOWING UP NOW IN THE HRRR RUNS WOULD AGREE WITH THIS AS WELL. AFTER THAT... SUBSIDENCE TAKING HOLD SHOULD SHUT OFF ANY PRECIPITATION ACTION. LOOKING AHEAD TO AFTER MIDNIGHT TONIGHT...SHORTWAVE TROUGH OVER BRITISH COLUMBIA ALONG WITH A WEAKER SHORTWAVE CURRENTLY SEEN OVER IDAHO ARE FORECAST TO BEGIN TO DROP DOWN INTO MINNESOTA AROUND 12Z TUESDAY. WARM ADVECTION AHEAD OF THESE SHOULD RESULT IN A MID CLOUD DECK OF STRATUS...WHILE ANY PRECIPITATION STAYS NORTHWEST OF THE FORECAST AREA. REGARDING TEMPERATURES...WITH COLD ADVECTION OCCURRING TODAY NOTED BY 850MB TEMPS FALLING TO -5 TO -8C BY 18Z...ANTICIPATING GENERALLY STEADY OR FALLING TEMPERATURES. TONIGHT IS A LITTLE TRICKY WITH STRATUS OVER WISCONSIN AND THEN CLOUDS COMING IN AFTER MIDNIGHT EVERYWHERE. FOR NOW HAVE FOLLOWED A BLEND OF GUIDANCE FOR LOWS. WEDNESDAY AND WEDNESDAY NIGHT...SHORTWAVE OVER MINNESOTA AT 12Z WEDNESDAY IS FORECAST TO SHIFT EAST FAIRLY QUICKLY...REACHING LOWER MICHIGAN BY 00Z THURSDAY. BIGGEST CONCERN WITH THIS SHORTWAVE IS POTENTIAL FOR SOME WARM ADVECTION LIGHT SNOW SKIRTING TAYLOR AND CLARK COUNTIES. THE 00Z NAM/26.21Z SREF SUGGEST THIS IS POSSIBLE... WHEREAS THE 27.00Z GFS/26.12Z ECMWF ARE DRY. GIVEN THE WAY RECENT SYSTEMS HAVE GONE...WITH LIGHT PRECIPITATION HAPPENING DESPITE PRESENCE OF LOW LEVEL DRY AIR...FEEL COMPELLED TO AT LEAST PLACE A 20 PERCENT CHANCE IN TAYLOR AND CLARK COUNTIES. ELSEWHERE...A DECREASING CLOUD TREND SHOULD OCCUR WITH TEMPERATURES CLIMBING INTO THE 30S. COULD SEE READINGS PUSH 40 IN FAR WESTERN AREAS. FOR WEDNESDAY NIGHT...ATTENTION RE-FOCUSES TO THE NORTHWEST WHERE MODELS SHOW A DECENT SHORTWAVE MOVING THROUGH A FAST WEST-NORTHWEST UPPER LEVEL FLOW. AT 00Z...MODELS SUGGEST IT IS EITHER OVER EASTERN MONTANA OR SOUTHEAST SASKATCHEWAN...THEN IT MARCHES SOUTHEAST INTO THE FORECAST AREA AROUND 12Z THURSDAY. AS FAR AS WHERE IN THE FORECAST AREA...THIS VARIES GREATLY...SO FOR NOW HAVE TAKEN A BLEND APPROACH GIVEN THE FAST FLOW. AS THE SHORTWAVE APPROACHES...SHOULD SEE MID AND HIGH CLOUDS DEVELOP IN RESPONSE TO WARM ADVECTION AND DPVA FORCING. LIGHT PRECIPITATION COULD EVEN START BREAKING OUT IN NORTHWESTERN PORTIONS OF THE AREA IN THE EVENING. AFTER MIDNIGHT... ANTICIPATING SOME LIGHT PRECIPITATION EVERYWHERE. PRECIPITATION CHANCES REMAIN IN THE 20 TO 30 RANGE...HOWEVER...DUE TO THE LARGE SPREAD IN TRACK OF THE SHORTWAVE. ENVISION CHANCES NEEDING A BUMP UP IN LATER FORECASTS...BUT WHERE IS THE QUESTION. WITH THE CLOUDS MOVING IN...NOT ANTICIPATING AS MUCH OF A TEMPERATURE FALL AS TONIGHT. GENERALLY FOLLOWED A BLEND OF GUIDANCE FOR LOWS. THURSDAY AND THURSDAY NIGHT...SIMILAR TO THE PAST FEW DAYS...THE PARADE OF SHORTWAVES FROM THE PACIFIC CONTINUE TO COME THROUGH THE FAST FLOW. SHORTWAVE THAT IS NEAR/OVER THE AREA AT 12Z THURSDAY IS PROGGED TO REACH LOWER MICHIGAN BY 00Z...WHILE ANOTHER SHORTWAVE MOVES INTO THE DAKOTAS. SHOULD SEE THE PRECIPITATION DIMINISH FOR A TIME THURSDAY...ESPECIALLY IN THE AFTERNOON NORTH OF I-90 AS THAT AREA GETS INTO THE SUBSIDENCE BEHIND THE MORNING SHORTWAVE. DURING THE AFTERNOON...PRECIPITATION IS POSSIBLE SOUTH OF I-90 AS WARM ADVECTION OCCURS DOWNSTREAM OF THE SHORTWAVE ENTERING THE DAKOTAS. WITH UNCERTAINTY ON THE PLACEMENT OF THE SHORTWAVE NEAR/OVER THE AREA AT 12Z THURSDAY...ALONG WITH SUGGESTIONS OF LOW LEVEL DRY AIR TO OVERCOME IN SOUNDINGS...HAVE KEPT PRECIPITATION CHANCES BETWEEN 20 AND 30. A LOT OF UNCERTAINTY EXISTS WITH THIS DAKOTAS SHORTWAVE HEADING INTO THURSDAY NIGHT...WHERE THE 27.00Z ECMWF/UKMET DROP IT DOWN INTO MISSOURI WHEREAS THE 27.00Z GFS CROSSES IOWA AND THE 27.00Z NAM CROSSES THE FORECAST AREA. FEELING IS THE SOUTHERN SOLUTIONS MAY HAVE A BETTER CHANCE OF VERIFYING...DUE TO THE USUAL BETTER PREDICTABILITY OF THE ECMWF...BUT NOT COMPLETELY SURE GIVEN THE FAST FLOW. THEREFORE...20 TO 30 PERCENT CHANCES CONTINUE FOR THURSDAY NIGHT. WITH SO MUCH UNCERTAINTY ON THE TRACKS OF THESE SHORTWAVES...TEMPERATURE FORECASTS ARE PROBLEMATIC. CERTAINLY POTENTIAL EXISTS ON THURSDAY FOR AT LEAST THE SOUTHERN PORTION OF THE AREA TO HIT 40 OR HIGHER...ESPECIALLY IF THE SHORTWAVE THEN TRACKS FARTHER NORTH. CLOUDS THURSDAY NIGHT SHOULD HOLD TEMPERATURES UP IN THE 20S TO LOW 30S...COLDEST IN TAYLOR AND CLARK COUNTIES WHERE COOLER AIR SINKS SOUTH BEHIND THE SHORTWAVE MOSTLY SUGGESTED TO TRACK NEAR OR SOUTH OF THE AREA. .LONG TERM...FRIDAY THROUGH MONDAY NIGHT 305 AM CST TUE DEC 27 2011 27.00Z MODEL CYCLE CONSISTING OF THE ECMWF/GFS/CANADIAN AND GFS ENSEMBLES STILL PRESENT PLENTY OF UNCERTAINTY WITH REGARDS TO THE UPPER LEVEL PATTERN THROUGHOUT THE LONG TERM PERIOD...THOUGH THERE ARE SOME FEATURES THAT CAN BE LATCHED ONTO. THE FIRST IS A FAIRLY POTENT SHORTWAVE TROUGH POISED TO COME INTO THE PACIFIC NORTHWEST ON FRIDAY...RESULTING IN BUILDING RIDGING DOWNSTREAM TOWARDS THE FORECAST AREA. THIS RIDGING LOOKS TO BUILD INTO THE AREA FRIDAY NIGHT...BRINGING IN A SURGE OF DOWNSLOPED PACIFIC AIR. TIMING THE PACIFIC NORTHWEST SHORTWAVE TROUGH AND INTENSITY WILL BE CRITICAL IN DETERMINING HOW WARM NEW YEARS EVE IS. LOOKS LIKE THERE SHOULD BE SOME WARM ADVECTION PRECIPITATION DOWNSTREAM INTO THE AREA FRIDAY/FRIDAY NIGHT...BUT THIS MOSTLY LIFTS NORTH ON NEW YEARS EVE. THE 26.12Z/27.00Z ECMWF RUNS ARE BY FAR THE MOST AMPLIFIED... RESULTING IN A SLOWER COLD FRONTAL PASSAGE AND HIGH TEMPERATURES SATURDAY FROM THE 40S INTO THE LOW 50S. FOR NOW HAVE TAKEN A 30 DAY BIAS CORRECTION OF THE CONSENSUS OF ALL GUIDANCE...WHICH RESULTS IN HIGHS MOSTLY IN THE 40S. CERTAINLY POTENTIAL EXISTS FOR WARMER READINGS GIVEN LACK OF SNOW COVER STILL ANTICIPATED. COLDER AIR WILL MOVE INTO THE AREA FOR NEW YEARS DAY AS THE UPPER TROUGH MOVES IN...BUT HOW MUCH DEPENDS ON THE PROGRESSIVE NATURE OF THE UPPER TROUGH. THE MORE AMPLIFIED ECMWF BASICALLY TURNS THE TROUGH INTO A LONGWAVE TROUGH...ALLOWING FOR AIR OF MORE ARCTIC ORIGIN TO FLOW SOUTH INTO THE AREA FOR NEW YEARS DAY AND MONDAY. ON THE OTHER HAND...THE 27.00Z GFS/CANADIAN DEPICT MUCH MORE PROGRESSION... RESULTING IN A CONTINUED FEED OF PACIFIC AIR AND WARMER. GIVEN SO MUCH UNCERTAINTY...A CONSENSUS OF GUIDANCE WAS FOLLOWED FOR NEW YEARS DAY THROUGH MONDAY NIGHT. IN EITHER MODEL CAMP SCENARIO...IT LOOKS LIKE LITTLE IF ANY PRECIPITATION WILL OCCUR. && .AVIATION...TODAY AND TONIGHT 521 AM CST TUE DEC 27 2011 GUSTY NORTHWEST WINDS AND MVFR STRATUS ARE THE MAIN CONCERNS TODAY. A TIGHT PRESSURE GRADIENT WILL BE IN PLACE ACROSS THE AREA TODAY AS A DEEPENING LOW PRESSURE SYSTEM MOVES INTO THE GREAT LAKES REGION. THIS WILL RESULT IN NORTHWEST WINDS IN THE 15 TO 25KT RANGE WITH GUSTS AROUND 30KT. LOOK FOR THE STRATUS TO SCATTER FROM WEST TO EAST THIS AFTERNOON AS HIGH PRESSURE AND DRIER AIR MOVES IN FROM THE PLAINS. EXPECTING VFR CONDITIONS BY 20Z AT KRST AND AROUND 21Z AT KLSE. THE GUSTY WINDS WILL SUBSIDE AROUND SUNSET. LOOK FOR HIGH/MID LEVEL CLOUDS TO SPREAD INTO AND THICKEN ACROSS THE AREA THIS EVENING AND OVERNIGHT AHEAD OF A WARM FRONT MOVING ACROSS THE NORTHERN PLAINS. OTHERWISE...VFR CONDITIONS EXPECTED TO PREVAIL TONIGHT. && .ARX WATCHES/WARNINGS/ADVISORIES... 305 AM CST TUE DEC 27 2011 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...DAS
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
554 AM EST THU DEC 29 2011 .AVIATION... / 12Z TAFS / WARM FRONT ASSOCIATED WITH AN APPROACHING SHORTWAVE TROUGH ACROSS THE UPPER MIDWEST WILL MIX NEWD THROUGH THE FA TODAY ALLOWING WINDS TO VEER AND BECOME SOMEWHAT GUSTY BY LATE MORNING/AFTN. A NARROW BROKEN BAND OF LIGHT MIXED PRECIPITATION ACROSS NRN IL AND SRN WI MAY BRING A BRIEF PERIOD OF MAINLY LIQUID PRECIP TO THE TERMINALS THIS MORNING. SFC TEMPS SHOULD BE BETWEEN 30 AND 32 AT SBN WHEN THIS MOVES THROUGH SO CONTINUED WITH A 12-14Z TEMPO GROUP FOR -FZRA HERE. THIS ACTIVITY MAY IMPACT FWA LATER THIS MORNING WITH TEMPS LIKELY JUST ABOVE FREEZING BY THEN. KEPT VIS/CIGS VFR WITH THE FRONTAL PASSAGE...ALTHOUGH CANNOT RULE OUT A TIME OF MVFR CONDITIONS DURING THIS TIME...ESPECIALLY BTW 15-20Z. OTHERWISE DRY/VFR LATER THIS AFTN AND EVENING WITH DETERIORATING FLIGHT CONDITIONS POSSIBLE TOWARDS DAYBREAK THURSDAY AS THE NEXT SHORTWAVE AND CHANCE FOR RAIN MOVES IN. && .PREV DISCUSSION... /ISSUED 355 AM EST THU DEC 29 2011/ SHORT TERM... / TODAY THROUGH FRIDAY NIGHT / 08Z SFC ANALYSIS SHOWS A SFC LOW NEAR MSP WITH A WARM FRONT EXTENDING SE INTO EASTERN IA AND WC IL. THE ASSOCIATED LOW AMPLITUDE SHORTWAVE OVER THE UPPER MIDWEST WILL SHEAR OUT TOWARDS THE CENTRAL GREAT LAKES TODAY ALLOWING THE WARM FRONT TO SURGE NEWD INTO THE SRN GREAT LAKES. RATHER MODEST OVERRUNNING/ISENTROPIC UPGLIDE EXPECTED JUST AHEAD OF THIS WARM FRONT THIS MORNING INTO EARLY THIS AFTERNOON (40 KNOTS OF CROSS ISOBARIC FLOW ON THE I290 SFC). UPSTREAM OBS/MOSAIC RADAR AND THE BULK OF 00Z GUIDANCE SUGGEST THAT NORTHERN AREAS MAY SEE A BRIEF PERIOD (AN HOUR OR TWO) OF VERY LIGHT PCPN THIS MORNING INTO EARLY THIS AFTN...WITH THE BETTER CHANCES FOR MEASURABLE PCPN (A COUPLE HUNDREDTHS AT BEST) BEING ACROSS THE NORTH/NORTHEAST WITH MAINLY VIRGA SOUTHWEST. LATEST RUC SOUNDINGS AND SFC OBS CONTINUE TO SUPPORT A POSSIBLE LIGHT MIX OF FREEZING DRIZZLE/SNOW TO START...LIKELY TRANSITIONING TO A BRIEF PERIOD OF DRIZZLE. ANY FREEZING DRIZZLE/RAIN BTW 12-15Z MAY CREATE A FEW SLICK SPOTS ON AREA ROADS...MAINLY NORTH OF ROUTE 6. OTHERWISE...EXPECT WINDS WILL PICK UP AND VEER BEHIND THE FRONTAL BOUNDARY WITH GUSTS OF 20-25 KNOTS POSSIBLE. A MUCH MORE VIGOROUS SHORTWAVE NOW ACROSS THE PAC NW WILL DIG INTO THE MID MS VALLEY AND NRN OH VALLEY BY LATER TONIGHT AND FRIDAY. GFS/ECMWF AGREE ON 120-140 METER 500 MB HEIGHT FALLS WITH THIS FEATURE SUPPORTING A RATHER HEALTHY LOW LVL RESPONSE AND THETA-E ADV INTO THE AREA WITH PCPN FOCUSING ALONG A DEEPENING BAROCLINIC ZONE. A MODEL CONSENSUS FAVORS THE NORTHERN HALF OF THE FA FOR BEST CHANCES FOR MEASURABLE RAINFALL. AMOUNTS ARE FCST TO RANGE BETWEEN 0.20" AND 0.50" HERE. HIRES GUIDANCE IS A LITTLE FARTHER SOUTH WITH THE TRACK OF THIS SYSTEM SO DID CONTINUE WITH CHC/SLIGHT WORDING FOR SNOW IN THE FAR NORTH...WITH AREAS JUST NORTH OF THE FA IN A GOOD POSITION FOR A MODERATE SNOWFALL. OTHERWISE...TEMPS ARE FCST TO BE ABOVE NORMAL THIS PERIOD WITH ONLY MINOR TWEAKS MADE. LONG TERM... OVERALL LARGE SCALE PATTERN STILL EXPECTED TO BECOME MORE AMPLIFIED THROUGH THE LONG TERM WITH BRIEF ARCTIC INTRUSION STILL EXPECTED LATTER HALF OF WEEKEND INTO NEXT WEEK. MEDIUM RANGE MODELS REMAIN IN GOOD AGREEMENT ON LARGE SCALE WITH DIFFERENCES CONTINUING IN THE DETAILS. CR ALLBLEND LOADED AND COLLABORATED SOME TWEAKS TO TEMPS AND POPS. A QUIET START EXPECTED ON SATURDAY WITH WARM AIR ADVECTION AHEAD OF FIRST COLD FRONT AND TEMPERATURES RISING WELL ABOVE NORMAL FOR LATE DECEMBER. SHOULD SEE 40S ACROSS ENTIRE AREA FOR HIGHS WITH 50S NOT OUT OF QUESTION SOUTH AND WEST. WARM AIR ADVECTION CONTINUES FIRST HALF OF SATURDAY NIGHT WITH TEMPS STEADY OR SLOWLY RISING UNTIL INITIAL FRONTAL PASSAGE LATE. HAVE TRIED TO DETAIL THIS SCENARIO IN HOURLY GRIDS WITH STEADY TEMPS THROUGH 06Z THEN A SLOW FALL TOWARD 12Z. DETAIL DIFFERENCES AND COMPLICATIONS IN FORECAST BEGIN IN THIS SATURDAY NIGHT INTO SUNDAY TIME FRAME WITH STRENGTH AND TIMING OF COLD AIR ADVECTION AND ANY ASSOCIATED PCPN. 850MB TEMPS BEGIN TO FALL AFTER 06Z SUNDAY WITH 1000-850MB THICKNESSES FOLLOWING. MODELS SHOWING LITTLE IN WAY OF PCPN WITH THIS FRONT GIVEN POSITIVELY TILTED UPPER SYSTEM AND NO STRONG MOISTURE SURGE AHEAD OF IT. DEEPENING SURFACE LOW REMAINS WELL NORTH OF AREA WITH ONLY SUBTLE INDICATIONS OF SECONDARY LOW DEVELOPMENT ALONG FRONT BY A FEW MODELS. HAVE THEREFORE ALLOWED LOW CHANCE POPS TO RIDE SAT NIGHT AND SUNDAY MORNING. SUNDAY BEGINNING TO LOOK DRY IN WAKE OF INITIAL COLD FRONT WITH SOME SUNSHINE EVEN POSSIBLE IN DRY SLOT BEFORE SECONDARY ARCTIC FRONT LATER IN THE DAY. IF THIS OCCURS...FALLING TEMPS EARLY IN THE MORNING MAY BECOME STEADY OR EVEN RISE A FEW DEGREES BEFORE SECONDARY FRONT BRINGS MUCH COLDER AIR IN DURING THE AFTERNOON. FOR NOW HAVE CHOSEN TO GO WITH SLOWLY FALLING TEMPS DURING THE DAY GIVEN TEMPS LOOK TO FALL IN THE AFTERNOON REGARDLESS. WITH ARCTIC INTRUSION SUNDAY NIGHT WILL SEE BEST LAKE EFFECT SNOW POTENTIAL OF THE SEASON AS DELTA T VALUES CLIMB WITH SURFACE TO 850MB WELL INTO LOWER 20S. SURFACE TO 700MB DELTA T VALUES REACH CRITICAL 30C THRESHOLD WHICH IS A GOOD INDICATOR OF HEAVY SNOW POTENTIAL. LIMITING FACTOR CONTINUES TO BE MOISTURE PROFILES BUT MEDIUM RANGE MODELS ARE SHOWING SOME DECENT SYNOPTIC MOISTURE LATE SUNDAY NIGHT THROUGH MONDAY WHICH WOULD SUPPORT A PERIOD OF HEAVY LAKE EFFECT SNOW BANDS. NORTHWEST FLOW AND WIND FIELD SUGGEST MULTI-BANDED EVENT WHICH MAKES PINNING DOWN AMOUNTS AND LOCATIONS DIFFICULT AT THIS TIME PROJECTION. HAVE BUMPED NW FETCH FAVORED AREAS INTO LIKELY CATEGORY FOR NOW. HEADLINES POSSIBLE LATER THIS WEEKEND INTO EARLY NEXT WEEK AS MOISTURE PROFILES BECOME BETTER DEFINED BY HIGHER RESOLUTION MODELS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 11 PM EST THIS EVENING FOR LMZ043. SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LMZ046. && $$ SHORT TERM...STEINWEDEL LONG TERM...LASHLEY AVIATION...STEINWEDEL
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
858 AM CST THU DEC 29 2011 .AVIATION... CURRENTLY VFR CEILINGS ACROSS THE MID MISSISSIPPI VALLEY THIS MORNING WITH MVFR TO IFR CEILINGS ACROSS CENTRAL MINNESOTA. UPDATED THE PREVIOUS SET OF TAFS TO REMOVE MVFR CEILINS AT KDBQ AS AS THE LOWER CEILINGS ARE EXPECTED TO REMAIN TO THE NORTH AND EAST OF THESE TAF SITES. DC/JH && .PREV DISCUSSION... /ISSUED 652 AM CST THU DEC 29 2011/ UPDATE... A FEW SHRA/S HAVE DEVELOPED FROM NEAR QUAD CITIES S/E WITHIN AREA OF MID LEVEL INSTABILITY AHEAD OF VORT MAX. UPDATED TO ADD ISOLD MENTION AND SHOULD BE OUT OF CWA NEXT 1-2 HRS. NEXT CONCERN IS CLOUD TRENDS. LEADING EDGE OF STRATUS HAS DISSIPATED OVER SOUTHERN MN AND NOTICING PAST FEW HRS OF CIG TRENDS FROM RUC BACKUP MODEL KEEPS LOW CLOUDS TO N/W OF CWA TDY. THIS LOOKS REASONABLE GIVEN RECENT TRENDS PLUS THE ADDITIONAL RAPID EROSION TO STRATUS OVER ND DUE TO WARM ADVECTION ALOFT. WILL BE UPDATING TO BE MORE OPTIMISTIC WITH SKY COVER NORTH HALF AND TWEAK MAXES UP A COUPLE DEGS. PREV DISCUSSION... /ISSUED 411 AM CST THU DEC 29 2011/ SYNOPSIS... STARTING OUT THIS AM WITH TEMPS THAT ALREADY AT OR 5+ DEGS ABOVE NORMAL HIGHS. ALWAYS A GREAT SIGN AND HARBINGER OF WHAT IS TO COME TDY. QUASI-ZONAL FLOW FULL OF ENERGY EARLY THIS AM. WATER VAPOR IMAGERY AND PROFILERS DEPICT SHORTWAVE NEAR PICKLE LAKE ONTARIO (CYPL) WITH SECONDARY WAVE FURTHER SOUTH NEAR LACROSSE WI... BOTH SLIDING E/SE. ATTENDANT SFC LOW WAS LOCATED CLOSE TO SAINT CLOUD MN WITH COLD FRONT EXTENDING WNWD INTO NORTHERN SD WHILE WARM FRONT WAS DRAPED SEWD INTO EASTERN IA. WARM ADVECTION WING WITH JUST TRACE AMOUNTS OF PCPN PASSING QUICKLY THROUGH NORTHERN IL. MOST OBS THIS FAR SOUTH HAVE BEEN REPORTING SPRINKLES BUT A COUPLE OF QUESTION MARKS SHOWING ON SOME ASOS NEAR WI/IL BORDER INTO SOUTHERN WI AND SO CANT RULE OUT SOME FLAKES OR EVEN ICE PELLETS BUT NO GROUND TRUTH REPORTS. THIS WILL BE EXITING SHORTLY WITH SKIES CLEARING INTO EASTERN IA IN WAKE OF WARM ADVECTION. SATL SHOWS A LARGE AREA OF LOW CLOUDS OVER ND... FAR NORTHEAST SD AND WESTERN MN ON BACKSIDE OF SFC LOW IN LOW LEVEL COLD ADVECTION WHICH HAVE BEEN SLIDING SEWD. MEANWHILE... NEXT BARRAGE OF ENERGY IN VERY ENERGETIC PACIFIC WAVE TRAIN PLOWING THROUGH PACIFIC NW AND NORTHERN ROCKIES... AND ITS THIS ENERGY THAT WILL AID IN BRINGING PCPN TO PORTIONS OF THE REGION TNGT-FRI. SHORT TERM...TODAY AND TONIGHT... EYES ARE POINTED NW EARLY THIS AM. SFC LOW OVER CENTRAL MN TO DIVE E/SE THROUGH SOUTHERN WI TDY WITH TRAILING COLD FRONT SWEEPING ACROSS THE CWA. THUS... WARM ADVECTION ON GUSTY SW WINDS TO START OFF WILL EVENTUALLY BE REPLACED WITH COLD ADVECTION ON GUSTY W/NW WINDS. BEST COLD ADVECTION PROGGED NORTH THIRD TO HALF OF CWA WHERE ALSO EXPECT TO SEE SOME STRATUS TURNING SKIES FROM SUNNY TO PT-MOCLDY. TEMPS EVERYWHERE WELL ABOVE NORMAL BY CLOSE TO 15+ DEGS... WITH COOLEST READINGS NORTH WHERE WENT WITH AROUND 40/L40S DUE TO ANTICIPATION OF LOW CLOUDS BY MID-LATE AM. FROM THERE ON SOUTH TEMPS WARMING WELL INTO THE 40S WITH 50S OVER SE IA... WCNTRL IL AND NE MO. TNGT... ANOTHER DOUBLE BARREL ENERGY COMPLEX EXPECTED TO SHIFT FROM THE PLAINS INTO UPPER MIDWEST. ROBUST WARM ADVECTION TO GENERATE PCPN THAT WILL MOVE ACROSS MUCH OF AREA BY MID-LATE EVE AND OVRNGT ESPECIALLY NORTH OF KOTM-KBRL LINE. FCST SOUNDINGS AND LATEST SUITE OF SREF PTYPE PROBS ALL SUPPORT PCPN WILL BE RAIN. UKMET AND ECMWF STRONGER WITH ENERGY RESULTING IN DEEPER SFC LOW FOR EVEN WARMER DRAW AGAIN SUPPORTING RAIN AS THEY SHOW H85 LOW MOVING INTO NE IA 12Z FRI... PLACING BETTER SNOW CHCS NORTH OR LEFT OF THE H85 LOW TRACK. QPF AMOUNTS WILL BE LIGHT AND GENERALLY A TENTH OR TWO AT MOST. TEMPS WILL DROP OFF A BIT EARLY THIS EVE THEN BECOME STEADY AND SLOWLY RISE WITH ONSET OF LOW LEVEL WARM ADVECTION. ..05.. LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY... FRIDAY...STILL SOME VARIANCE BETWEEN THE 00Z MODEL RUNS INTO FRI WITH HANDLING AND DEVELOPMENT OF THE PASSING WAVE COMPLEX. BUT WITH THE PROGRESSIVE NATURE OF THE CURRENT REGIME PATTERN WE HAVE BEEN IN THIS WEEK AND LOOKING AT UPPER JET DYNAMICS THROUGH FRI NIGHT... FEEL THE 00Z RUN GFS SOLUTION THE ONE TO FOLLOW FOR NOW THIS PERIOD. ALSO PREFER THE FURTHER NORTH LOW TO MID LEVEL WAVE PROGRESSION ACRS THE REGION IN LINGERING POSITIVE AO. THIS ACCEPTED GFS SOLUTION SUGGESTS BULK OF ANY PRECIP SHIELD ASSOCIATED WITH THE PASSING LOW WILL BE ON THE MOVE OUT OF THE DVN CWA FRI MORNING AFTER 12Z. WILL WALK OUT PRECIP IN THE MORE WITH LIKELY POPS IN THE FAR NORTHEAST... AND LESSER CHC POPS FURTHER TO THE WEST AND SOUTH. IT ALSO APPEARS IN-WRAPPING LLVL COLD CONVEYOR OR TOP-DOWN COOLING ENOUGH FOR A CHANGE OVER TO SNOW WILL OCCUR AFTER THE BULK OF ANY MEASURING PRECIP EXITS THE AREA AS WELL. BUT PROJECTED THERMAL PROFILES ARE CLOSE THROUGH 15Z FRI ALONG AND NORTH OF THE HWY 20 CORRIDOR AND WILL MENTION A MIX IN THOSE AREAS BUT WITH LITTLE IF ANY SNOW ACCUM. LOW TO MID LEVEL DRYING/RH DECREASE LATE MORNING THOUGH MIDDAY AS LOW CENTER PASSES...THEN SYSTEM WRAP AROUND STRATOCU ENGULFS MUCH OF THE CWA FRI AFTERNOON INTO THE EVENING. EXTENT OF PRECIP POTENTIAL IN THIS WRAP AROUND DECK UNCERTAIN ALONG WITH ADEQUATE MOISTURE DEPTH FOR MEASURABLE. FOR NOW WILL JUST GO WITH A SLIGHT CHC OF LIGHT RAIN OR LIGHT SNOW IN THE FAR NORTH FRI AFTERNOON...BUT IT MAY BE NOT MUCH MORE THAN FLURRIES OR SPRINKLES. FRI HIGHS RANGING FROM AROUND 40 IN THE FAR NORTH..TO NEAR 50 IN THE FAR SOUTH. THEN EXPECT THE CLOUDS TO CLEAR TO THE EAST FRI NIGHT WITH SFC WIND DROP OFF WITH PASSING SFC RIDGE LOBE. LOWS IN THE UPPER 20S TO LOWER 30S FOR NOW BUT IT MAY BE COOLER DEPENDING ON IF RETURN FLOW CAN COMMENCE TOWARD SAT MORNING IN TIME TO HALT THE TEMP DROP-OFF ESPECIALLY WEST OF THE MS RVR. SATURDAY AND SUNDAY...LOOKING AT THE LATEST 00Z RUN MEDIUM RANGE MODELS AND WARM UP POTENTIAL AHEAD OF A SUBSTANTIAL IMPULSE TRYING TO PHASE OVER THE MID CONUS ON SAT...DURATION OF THE WARM TONGUE AND MIXING DEPTH STILL AT QUESTION ENOUGH TO FUEL THE ADVERTISED DAY WELL IN THE 50S. WILL MAKE ONLY MINOR ADJUSTMENTS TO SAT HIGHS FOR NOW AS STILL SOMEWHAT HESITANT TO GO CRAZY WITH THE FULL WARM UP POTENTIAL. BUT EVEN WITH THE CURRENT PROJECTED THERMAL PROFILES AND FCST SOUNDINGS...JUST MIXING UP TO AROUND H9 MB/INTO BASE OF A VERY PRONOUNCED WARM WEDGE ALOFT/INVERSION CENTERED AROUND H85 MB...HIGHS WOULD BE IN THE MID 50S WITH A FEW LOCATIONS PUSHING THE UPPER 50S IN THE SOUTHWESTERN CWA. THE MODELS THEN REALLY START TO DIVERGE NEW YEARS EVE/SAT NIGHT WITH RESPECT TO CONTINUED DEVELOP OF A L/W TROF AND ASSOCIATED DEEPENING LLVL CYCLONE OVER THE UPPER MIDWEST AND NORTHWESTERN GRT LKS. BUT THE GENERAL ENSEMBLES SUGGEST THAT THE DVN CWA WILL REMAIN DRY SAT NIGHT AND MILD THROUGH MIDNIGHT/HELD UP WELL IN THE 40S BEFORE IN-SWIRLING COLD PUSH MAKES IT ACRS THE AREA FROM NW-TO-SE AFTER 09Z SUNDAY. STILL SOME DETAILS TO REFINE WITH THIS PERIOD OVER THE NEXT 24-36 HRS OF MODEL RUNS. AS FOR NEW YEARS DAY SUNDAY...A WINDY RAW DAY WITH MORNING HIGHS AND THEN FALLING TEMPS AS NORTHWEST SFC WINDS GUST OVER 30 MPH IN ROBUST CAA REGIME UNDER AMPLIFYING PATTERN. THE ECMWF STILL THE MOST DEVELOPED WITH HIGH AMPLITUDE NEAR MERIDIONAL FETCH DEVELOPING ACRS THE WESTERN GRT LKS BY MONDAY MORNING. H85 TEMPS BY 12Z MON IN NEGATIVE MID TEENS C AND LOWS SUNDAY NIGHT PROBABLY WELL DOWN IN THE TEENS DESPITE ONGOING MIXING WINDS OF 15-25 MPH EVEN AT NIGHT. WILL KEEP SUNDAY DRY BUT IN SUCH A REGIME WOULD EXPECT COL AIR STRATUS TO BLANKET THE AREA ALONG WITH SOME EMBEDDED FLURRIES. MONDAY THROUGH WEDNESDAY...WILL KEEP HIGH AMPLITUDE ARCTIC AIRMASS DUMP INTO THE MIDWEST GOING MON AND MON NIGHT. MONDAY HIGHS PROBABLY NOT TO GET OUT OF THE LOW TO MID 20S WITH ONGOING GUSTY NORTHWEST WINDS OF 20-30 MPH AND HIGHER GUSTS. SFC RIDGE LOBE SLIDING ACRS THE CWA...SFC WIND DECOUPLE AND STRATUS CLEAR OFF COULD FOSTER SINGLE DIGIT LOWS OVER SOME PORTIONS OF THE DVN CWA BY TUE MORNING EVEN OVER SNOWCOVER-LESS TERRAIN. AGAIN WILL GO DRY IN THE GRIDS ON MONDAY BUT WOULD BET SOME CAA FLURRIES CONTINUING TO GET MILKED OUT OF WHATEVER MOISTURE THERE IS ACRS THE AREA. LONGER RANGE SIGNALS SUGGEST THE FLOW WILL TRY TO FLATTEN OUT AGAIN TOWARD MID NEXT WEEK AS ARCTIC OSCILLATION/AO PROGS MIGRATE BACK TOWARD THE POSITIVE. BUT THERMAL MODERATION INTO TUE TO BE SLOW AND MORE REALIZED BY NEXT WED WITH HIGHS RETURNING TO THE MID AND UPPER 30S. THIS PROCESS MAY BE AIDED BY A WARM DRAW TO THE SOUTH OF CLIPPER TYPE SYSTEM DROPPING FROM SASKATCHEWAN TO WI SOMETIME DURING THIS TUE INTO WED PERIOD. ..12.. AVIATION... /ISSUED 1137 PM CST WED DEC 28 2011/ && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
652 AM CST THU DEC 29 2011 .UPDATE... A FEW SHRA/S HAVE DEVELOPED FROM NEAR QUAD CITIES S/E WITHIN AREA OF MID LEVEL INSTABILTY AHEAD OF VORT MAX. UPDATED TO ADD ISOLD MENTION AND SHOULD BE OUT OF CWA NEXT 1-2 HRS. NEXT CONCERN IS CLOUD TRENDS. LEADING EDGE OF STRATUS HAS DISSIPATED OVER SOUTHERN MN AND NOTICING PAST FEW HRS OF CIG TRENDS FROM RUC BACKUP MODEL KEEPS LOW CLOUDS TO N/W OF CWA TDY. THIS LOOKS REASONABLE GIVEN RECENT TRENDS PLUS THE ADDITIONAL RAPID EROSION TO STRATUS OVER ND DUE TO WARM ADVECTION ALOFT. WILL BE UPDATING TO BE MORE OPTIMISTIC WITH SKY COVER NORTH HALF AND TWEAK MAXES UP A COUPLE DEGS. && .AVIATION... /ISSUED 558 AM CST THU DEC 29 2011/ CURRENTLY..WEAK RETURNS ARE SHOWING UP ON RADAR IN THE VICINITY OF KBRL AND KMLI AND MAY AFFECT THESE TERMINALS THROUGH 13 UTC. MVFR CEILINGS IN THE WAKE OF THIS MORINGS CLIPPER SYSTEM WILL BRUSH KDBQ BETWEEN 15 AND 18 UTC WITH SCT CEILINGS AT KCID. AFTER 18 UTC ALL TAF SITES WILL BE VFR THROUGH 03 UTC WHEN A MUCH STRONGER CLIPPER SYSTEM APPROACHES THE MID MISSISSIPPI VALLEY. MVFR CEILINGS MOVE INTO KCID AND KDBQ BY 06 UTC WITH PERIODS OF RAIN THROUGH THE END OF THE PERIOD. RAIN WILL NOT BE AS WIDESPREAD AT KBRL AND KMLI AND MAY ONLY OCCURR FOR A BRIEF PERIOD SO USED VCSH AS TIMING IS UNCERTAIN AND LEFT CEILINGS AT VFR WITH BETTER LOW LEVEL MOISTURE TO THE NORTH AND EAST. ..DC/MM.. && .PREV DISCUSSION... /ISSUED 411 AM CST THU DEC 29 2011/ SYNOPSIS... STARTING OUT THIS AM WITH TEMPS THAT ALREADY AT OR 5+ DEGS ABOVE NORMAL HIGHS. ALWAYS A GREAT SIGN AND HARBINGER OF WHAT IS TO COME TDY. QUASI-ZONAL FLOW FULL OF ENERGY EARLY THIS AM. WATER VAPOR IMAGERY AND PROFILERS DEPICT SHORTWAVE NEAR PICKLE LAKE ONTARIO (CYPL) WITH SECONDARY WAVE FURTHER SOUTH NEAR LACROSSE WI... BOTH SLIDING E/SE. ATTENDANT SFC LOW WAS LOCATED CLOSE TO SAINT CLOUD MN WITH COLD FRONT EXTENDING WNWD INTO NORTHERN SD WHILE WARM FRONT WAS DRAPED SEWD INTO EASTERN IA. WARM ADVECTION WING WITH JUST TRACE AMOUNTS OF PCPN PASSING QUICKLY THROUGH NORTHERN IL. MOST OBS THIS FAR SOUTH HAVE BEEN REPORTING SPRINKLES BUT A COUPLE OF QUESTION MARKS SHOWING ON SOME ASOS NEAR WI/IL BORDER INTO SOUTHERN WI AND SO CANT RULE OUT SOME FLAKES OR EVEN ICE PELLETS BUT NO GROUND TRUTH REPORTS. THIS WILL BE EXITING SHORTLY WITH SKIES CLEARING INTO EASTERN IA IN WAKE OF WARM ADVECTION. SATL SHOWS A LARGE AREA OF LOW CLOUDS OVER ND... FAR NORTHEAST SD AND WESTERN MN ON BACKSIDE OF SFC LOW IN LOW LEVEL COLD ADVECTION WHICH HAVE BEEN SLIDING SEWD. MEANWHILE... NEXT BARRAGE OF ENERGY IN VERY ENERGETIC PACIFIC WAVE TRAIN PLOWING THROUGH PACIFIC NW AND NORTHERN ROCKIES... AND ITS THIS ENERGY THAT WILL AID IN BRINGING PCPN TO PORTIONS OF THE REGION TNGT-FRI. SHORT TERM...TODAY AND TONIGHT... EYES ARE POINTED NW EARLY THIS AM. SFC LOW OVER CENTRAL MN TO DIVE E/SE THROUGH SOUTHERN WI TDY WITH TRAILING COLD FRONT SWEEPING ACROSS THE CWA. THUS... WARM ADVECTION ON GUSTY SW WINDS TO START OFF WILL EVENTUALLY BE REPLACED WITH COLD ADVECTION ON GUSTY W/NW WINDS. BEST COLD ADVECTION PROGGED NORTH THIRD TO HALF OF CWA WHERE ALSO EXPECT TO SEE SOME STRATUS TURNING SKIES FROM SUNNY TO PT-MOCLDY. TEMPS EVERYWHERE WELL ABOVE NORMAL BY CLOSE TO 15+ DEGS... WITH COOLEST READINGS NORTH WHERE WENT WITH AROUND 40/L40S DUE TO ANTICIPATION OF LOW CLOUDS BY MID-LATE AM. FROM THERE ON SOUTH TEMPS WARMING WELL INTO THE 40S WITH 50S OVER SE IA... WCNTRL IL AND NE MO. TNGT... ANOTHER DOUBLE BARREL ENERGY COMPLEX EXPECTED TO SHIFT FROM THE PLAINS INTO UPPER MIDWEST. ROBUST WARM ADVECTION TO GENERATE PCPN THAT WILL MOVE ACROSS MUCH OF AREA BY MID-LATE EVE AND OVRNGT ESPECIALLY NORTH OF KOTM-KBRL LINE. FCST SOUNDINGS AND LATEST SUITE OF SREF PTYPE PROBS ALL SUPPORT PCPN WILL BE RAIN. UKMET AND ECMWF STRONGER WITH ENERGY RESULTING IN DEEPER SFC LOW FOR EVEN WARMER DRAW AGAIN SUPPORTING RAIN AS THEY SHOW H85 LOW MOVING INTO NE IA 12Z FRI... PLACING BETTER SNOW CHCS NORTH OR LEFT OF THE H85 LOW TRACK. QPF AMOUNTS WILL BE LIGHT AND GENERALLY A TENTH OR TWO AT MOST. TEMPS WILL DROP OFF A BIT EARLY THIS EVE THEN BECOME STEADY AND SLOWLY RISE WITH ONSET OF LOW LEVEL WARM ADVECTION. ..05.. LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY... FRIDAY...STILL SOME VARIANCE BETWEEN THE 00Z MODEL RUNS INTO FRI WITH HANDLING AND DEVELOPMENT OF THE PASSING WAVE COMPLEX. BUT WITH THE PROGRESSIVE NATURE OF THE CURRENT REGIME PATTERN WE HAVE BEEN IN THIS WEEK AND LOOKING AT UPPER JET DYNAMICS THROUGH FRI NIGHT... FEEL THE 00Z RUN GFS SOLUTION THE ONE TO FOLLOW FOR NOW THIS PERIOD. ALSO PREFER THE FURTHER NORTH LOW TO MID LEVEL WAVE PROGRESSION ACRS THE REGION IN LINGERING POSITIVE AO. THIS ACCEPTED GFS SOLUTION SUGGESTS BULK OF ANY PRECIP SHIELD ASSOCIATED WITH THE PASSING LOW WILL BE ON THE MOVE OUT OF THE DVN CWA FRI MORNING AFTER 12Z. WILL WALK OUT PRECIP IN THE MORE WITH LIKELY POPS IN THE FAR NORTHEAST... AND LESSER CHC POPS FURTHER TO THE WEST AND SOUTH. IT ALSO APPEARS IN-WRAPPING LLVL COLD CONVEYOR OR TOP-DOWN COOLING ENOUGH FOR A CHANGE OVER TO SNOW WILL OCCUR AFTER THE BULK OF ANY MEASURING PRECIP EXITS THE AREA AS WELL. BUT PROJECTED THERMAL PROFILES ARE CLOSE THROUGH 15Z FRI ALONG AND NORTH OF THE HWY 20 CORRIDOR AND WILL MENTION A MIX IN THOSE AREAS BUT WITH LITTLE IF ANY SNOW ACCUM. LOW TO MID LEVEL DRYING/RH DECREASE LATE MORNING THOUGH MIDDAY AS LOW CENTER PASSES...THEN SYSTEM WRAP AROUND STRATOCU ENGULFS MUCH OF THE CWA FRI AFTERNOON INTO THE EVENING. EXTENT OF PRECIP POTENTIAL IN THIS WRAP AROUND DECK UNCERTAIN ALONG WITH ADEQUATE MOISTURE DEPTH FOR MEASURABLE. FOR NOW WILL JUST GO WITH A SLIGHT CHC OF LIGHT RAIN OR LIGHT SNOW IN THE FAR NORTH FRI AFTERNOON...BUT IT MAY BE NOT MUCH MORE THAN FLURRIES OR SPRINKLES. FRI HIGHS RANGING FROM AROUND 40 IN THE FAR NORTH..TO NEAR 50 IN THE FAR SOUTH. THEN EXPECT THE CLOUDS TO CLEAR TO THE EAST FRI NIGHT WITH SFC WIND DROP OFF WITH PASSING SFC RIDGE LOBE. LOWS IN THE UPPER 20S TO LOWER 30S FOR NOW BUT IT MAY BE COOLER DEPENDING ON IF RETURN FLOW CAN COMMENCE TOWARD SAT MORNING IN TIME TO HALT THE TEMP DROP-OFF ESPECIALLY WEST OF THE MS RVR. SATURDAY AND SUNDAY...LOOKING AT THE LATEST 00Z RUN MEDIUM RANGE MODELS AND WARM UP POTENTIAL AHEAD OF A SUBSTANTIAL IMPULSE TRYING TO PHASE OVER THE MID CONUS ON SAT...DURATION OF THE WARM TONGUE AND MIXING DEPTH STILL AT QUESTION ENOUGH TO FUEL THE ADVERTISED DAY WELL IN THE 50S. WILL MAKE ONLY MINOR ADJUSTMENTS TO SAT HIGHS FOR NOW AS STILL SOMEWHAT HESITANT TO GO CRAZY WITH THE FULL WARM UP POTENTIAL. BUT EVEN WITH THE CURRENT PROJECTED THERMAL PROFILES AND FCST SOUNDINGS...JUST MIXING UP TO AROUND H9 MB/INTO BASE OF A VERY PRONOUNCED WARM WEDGE ALOFT/INVERSION CENTERED AROUND H85 MB...HIGHS WOULD BE IN THE MID 50S WITH A FEW LOCATIONS PUSHING THE UPPER 50S IN THE SOUTHWESTERN CWA. THE MODELS THEN REALLY START TO DIVERGE NEW YEARS EVE/SAT NIGHT WITH RESPECT TO CONTINUED DEVELOP OF A L/W TROF AND ASSOCIATED DEEPENING LLVL CYCLONE OVER THE UPPER MIDWEST AND NORTHWESTERN GRT LKS. BUT THE GENERAL ENSEMBLES SUGGEST THAT THE DVN CWA WILL REMAIN DRY SAT NIGHT AND MILD THROUGH MIDNIGHT/HELD UP WELL IN THE 40S BEFORE IN-SWIRLING COLD PUSH MAKES IT ACRS THE AREA FROM NW-TO-SE AFTER 09Z SUNDAY. STILL SOME DETAILS TO REFINE WITH THIS PERIOD OVER THE NEXT 24-36 HRS OF MODEL RUNS. AS FOR NEW YEARS DAY SUNDAY...A WINDY RAW DAY WITH MORNING HIGHS AND THEN FALLING TEMPS AS NORTHWEST SFC WINDS GUST OVER 30 MPH IN ROBUST CAA REGIME UNDER AMPLIFYING PATTERN. THE ECMWF STILL THE MOST DEVELOPED WITH HIGH AMPLITUDE NEAR MERIDIONAL FETCH DEVELOPING ACRS THE WESTERN GRT LKS BY MONDAY MORNING. H85 TEMPS BY 12Z MON IN NEGATIVE MID TEENS C AND LOWS SUNDAY NIGHT PROBABLY WELL DOWN IN THE TEENS DESPITE ONGOING MIXING WINDS OF 15-25 MPH EVEN AT NIGHT. WILL KEEP SUNDAY DRY BUT IN SUCH A REGIME WOULD EXPECT COL AIR STRATUS TO BLANKET THE AREA ALONG WITH SOME EMBEDDED FLURRIES. MONDAY THROUGH WEDNESDAY...WILL KEEP HIGH AMPLITUDE ARCTIC AIRMASS DUMP INTO THE MIDWEST GOING MON AND MON NIGHT. MONDAY HIGHS PROBABLY NOT TO GET OUT OF THE LOW TO MID 20S WITH ONGOING GUSTY NORTHWEST WINDS OF 20-30 MPH AND HIGHER GUSTS. SFC RIDGE LOBE SLIDING ACRS THE CWA...SFC WIND DECOUPLE AND STRATUS CLEAR OFF COULD FOSTER SINGLE DIGIT LOWS OVER SOME PORTIONS OF THE DVN CWA BY TUE MORNING EVEN OVER SNOWCOVER-LESS TERRAIN. AGAIN WILL GO DRY IN THE GRIDS ON MONDAY BUT WOULD BET SOME CAA FLURRIES CONTINUING TO GET MILKED OUT OF WHATEVER MOISTURE THERE IS ACRS THE AREA. LONGER RANGE SIGNALS SUGGEST THE FLOW WILL TRY TO FLATTEN OUT AGAIN TOWARD MID NEXT WEEK AS ARCTIC OSCILLATION/AO PROGS MIGRATE BACK TOWARD THE POSITIVE. BUT THERMAL MODERATION INTO TUE TO BE SLOW AND MORE REALIZED BY NEXT WED WITH HIGHS RETURNING TO THE MID AND UPPER 30S. THIS PROCESS MAY BE AIDED BY A WARM DRAW TO THE SOUTH OF CLIPPER TYPE SYSTEM DROPPING FROM SASKATCHEWAN TO WI SOMETIME DURING THIS TUE INTO WED PERIOD. ..12.. AVIATION... /ISSUED 1137 PM CST WED DEC 28 2011/ && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1043 AM EST THU DEC 29 2011 ...Forecast Update... Just some minor updates made to the grids late this morning. AC continues to move overhead, and will gradually move out of the region this afternoon. With the morning clouds giving a slow start to temperature rises, have dropped MaxT just a couple of degrees in the northeast where temperatures are coolest and clouds are most common and will be the most long-lived. BUFKIT has backed off on its wind gust forecasts for this afternoon, but the HRRR keeps us quite gusty and with the sun returning for the afternoon hours, will just knock the wind gust forecast down a couple knots. Gusts to 25 mph still look attainable...maybe even still to 30 mph over southern Indiana and northern Kentucky. Tweaked clouds in the far south and southwest where skies are clearer than farther north. && .Short Term (Today and Tonight)... A couple of low pressure systems will swiftly move across the Great Lakes region throughout the short-term, with the first occurring today, and the second fast on its heels late tonight. These two systems will not only bring increased mid-upper cloudiness to our region today and tonight, but will also increase our winds quite a bit out of the southwest. Because of this, temperatures will moderate some and will likely be at or just over the warmest MOS guidance. After a chilly start to today, expect highs under filtered sunshine to climb into the low-mid 50s, with lows tonight only dropping down to around 40 or the low 40s. With good mixing, expect 15mph sustained winds out of the southwest, with gusts as high as 25-30 at times from late morning through the afternoon hours. The second system approaching late tonight from the northwest will bring light rain to central IL/IN after midnight tonight. This activity should stay north of our CWA through 12z Friday so kept the latter portion of tonight`s forecast dry. .Long Term (Friday - Wednesday)... The models have come into much better agreement with the weather systems for the long term versus this time last night. There will be a couple of chances for precipitation through this period, though neither looks to bring widespread precip to the area. The first system will be Friday as a shortwave tracks across the upper Midwest and into the Great Lakes region. Southern Indiana and north central Kentucky will stand the best chance of seeing any light rain from this system as it quickly tracks eastward Friday. The rain will quickly move off to the east Friday evening, with Saturday remaining dry. For Friday winds will be fairly breezy out of the southwest. Temperatures Friday through Saturday will remain well above normal with highs in the mid 50s and lows in the upper 30s to lower 40s. For Sunday, a strong low pressure system will move out of WI/MN and into southern Canada. This will swing a strong cold front through on Sunday. Most of the moisture associated with this system looks to be closer to the low, so will continue to mention only slight chance to low chance pops. Additionally, models continue to speed up the exit of the precipitation. Think most precip will be out of the area before the cold air has a chance to overspread the region, so have taken out the mention of the rain/snow mix on Sunday night. Much colder air will settle into the Ohio Valley in the wake of this system. Highs on Monday will be only in the low to middle 30s while Tuesday`s highs may not make it out of the 20s in some locations. Lows will be in the lower 20s to teens. Wednesday looks to start a gradual warm up into the latter half of the week. && .Aviation (12Z TAF Issuance)... A couple of disturbances will cross the northern U.S. through this TAF period. Mid level clouds associated with the first system are already streaming across the region. Skies may clear for a bit this evening before more clouds move in overnight. The only concern today will be gusty winds this afternoon. Winds will increase out of the southwest after 15-16Z. Winds will be sustained at 12-15 knots with gusts to 22-25 knots. Gusts will decrease this evening, but winds will remain around 10 knots out of the southwest overnight. The second system crossing the area tomorrow may bring some light rain to SDF. However, with certainty low and little impact expected from the rain, will keep it out of the TAF for now. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Update...........13 Short Term.......AL Long Term........EER Aviation.........AL
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
631 AM EST THU DEC 29 2011 UPDATED AVIATION DISCUSSION FOR 12Z TAFS .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A STRONG WRLY MID/UPPER LEVEL FLOW INTO THE PAC NW AND WNW FLOW DOWNSTREAM FROM THE SRN CANADA AND NRN PLAINS INTO THE GREAT LAKES. ONE SHEARED SHORTWAVE TROUGH WAS LOCATED NORTH OF LAKE SUPERIOR AND ANOTHER WAS MOVING THROUGH SW MN. AT THE SFC...A 997 MB LOW WAS LOCATED OVER SRN MN RESULTING IN S TO SE WINDS ACROSS UPPER MICHIGAN. AN AREA OF SNOW FROM NE MN INTO WRN LAKE SUPERIOR NW WI WITH VSBYS INTO THE 1-3SM RANGE WAS SUPPORTED BY 285K-290K ASCENT AHEAD OF A 850-700 MB TROUGH. ANY LAKE EFFECT/ENHANCED SNOW OFF OF LAKE MICHIGAN WITH THE SRLY FLOW HAS BEEN MINIMAL WITH ONLY A DUSTING AT MOST. && .DISCUSSION... TODAY AND TONIGHT...EXPECT THE AREA OF SNOW TO PROGRESS ACROSS UPPER MICHIGAN TODAY. MODELS CONSENSUS QPF OF AROUND A TENTH OF AN INCH WITH SNOW/WATER RATIO VALUES NEAR 15/1 WOULD RESULT IN SNOWFALL AMOUNTS OF AN INCH OR TWO WHICH IS REASONABLE GIVEN 2G-3G/KG MOISTURE AVBL NEAR 700MB DURING A 6 HOUR PERIOD OF STRONGER LIFT. UNCERTAINTY REMAINS WITH REGARD TO LAKE ENHANCED SNOW POTENTIAL INTO THE SE CWA. THE HIGHER RES MODELS HAVE BEEN OVERDOING PCPN WITH BANDS OFF OF LAKE MICHIGAN SO FAR. HOWEVER...AS THE DEEPER MOISTURE ARRIVES...EXPECT THAT THE LAKE CONTRIBUTION MAY ADD AN ADDITIONAL 1-2 INCHES TO SNOWFALL AMOUNTS. SINCE THE WINDS WERE BACKING MORE SERLY AHEAD OF THE LOW...THE BEST LOW LEVEL CONV AND OVER WATER TRAJECTORIES HAVE SHIFTED TO THE WEST. SO...HAVE CANCELLED THE ADVY FOR LUCE COUNTY AND CONTINUED MENTION OF 2 TO 4 INCHES OF SNOW IN THE ADVY FOR SCHOOLCRAFT COUNTY TODAY. MODELS SUGGEST THAT THE DEEPER MOISTURE WILL QUICKLY DEPART THIS AFTERNOON OVER THE WEST. HOWEVER...LACK OF LOW LEVEL LIFT OR FOCUSING MECHANISM SHOULD MINIMIZE POTENTIAL FOR -FZDZ. SOME LIGHT SNOW WILL LINGER OVER THE ERN CWA TONIGHT AS THE SFC-850 MB TROUGH SLOWLY PIVOTS TO THE NORTHEAST. FRIDAY...MODELS WERE IN AGREEMENT THAT THE PCPN ASSOCIATED WITH A SHORTWAVE MOVING FROM THE PAC THROUGH THE NRN PLAINS INTO THE MS VALLEY AND SRN GREAT LAKES IS EXPECTED TO REMAIN SOUTH OF UPPER MI. SOME ISOLATED LIGHT SNOW SHOWERS MAY BE POSSIBLE NEAR AN INVERTED TROUGH AXIS INTO THE NRN CWA. AGAIN...-FZDZ MAY ALSO BE POSSIBLE BUT PROBABILITIES REMAIN LOW. SAT INTO SUN...THE NEXT MID LEVEL TROUGH IN THE PROGRESSIVE PATTERN WILL MOVE INTO THE REGION BY LATE SAT. WAA AHEAD OF THE MID LEVEL AND SFC TROUGH MAY BRING SOME LIGHT PCPN INTO THE WRN CWA. THE MORE CONSISTENT ECMWF WAS PREFERRED FOR DETAILS WITH THE SYSTEM AS THE GFS AND NAM HAVE AT TIMES SHOWED A STRONGER SHORTWAVE SWEEPING THROUGH THE REGION THAT WOULD GENERATE SUBSTANTIAL PCPN AND BRING MUCH GREATER DEEPENING OF THE SFC LOW. FALLING TEMPS AND BLUSTERY WNW WINDS ARE EXPECTED BY SUN AFTERNOON BEHIND A STRONG COLD FRONT. SUN NIGHT INTO TUE...AS THE PATTERN BRIEFLY AMPLIFIES...MUCH COLDER AIR WILL POUR INTO THE WRN LAKES ON NW TO N WINDS DROPPING 850 MB TEMPS TO AROUND -20C. SUBTLE MODEL DIFFERENCES REMAIN WITH THE PREVAILING WIND DIRECTION AS THE GFS REMAINS MORE TO THE NW COMPARED TO THE NRLY DIRECTION DEPICTED BY THE ECMWF/GEM. SIGNIFICANT LES REMAINS POSSIBLE WITH INTENSITY DROPPING OFF MON AS DEEPER MOISTURE DEPARTS. && .AVIATION /FOR THE 12Z TAF ISSUANCE/... A LOW PRESSURE SYSTEM MOVING S OF THE AREA TODAY WILL BRING -SN TO ALL TAF SITES...RESULTING IN IFR CONDITIONS. LIFR CONDITIONS ARE POSSIBLE AS WELL...ESPECIALLY AT KCMX...DURING PERIOD OF HEAVIEST SNOW. IMPROVEMENT EXPECTED W TO E LATE MORNING/AFTN AS MAIN AREA OF -SN EXITS. HOWEVER...IT MAY BE DIFFICULT TO GET RID OF THE LOWER CIGS GIVEN LIGHT LOW-LEVEL WINDS AND THUS WEAK ADVECTION OF ANY DRIER AIR AT THE LOW-LEVELS. SO...CIGS MAY REMAIN IFR OR ONLY RISE SLIGHTLY TO LOW MVFR IN THE AFTN. IWD IS THE MOST LIKELY TO SEE SIGNIFICANT IMPROVEMENT. && .MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/... A LOW PRESSURE SYSTEM OVER MN WILL MOVE EAST TODAY. ALTHOUGH WINDS SHOULD STAY BELOW GALE FORCE...THEY WILL BECOME RATHER GUSTY OUT OF THE SOUTHEAST WITH PERHAPS A GUST OR TWO CLOSE TO GALE FORCE. AFTER ANOTHER LOW MOVES ACROSS THE LOWER LAKES ON FRIDAY...A WEAK RIDGE BUILDS ACROSS LAKE SUPERIOR INTO SATURDAY BEFORE A STRONG LOW DEVELOPS OVER THE PLAINS AND MOVES NORTH OF LAKE SUPERIOR FOR NEW YEARS DAY. HIGH END NORTH-NORTHWEST GALES ARE POSSIBLE WITH THIS SYSTEM INTO MONDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ014- 085. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SYNOPSIS...JLB DISCUSSION...JLB AVIATION...TITUS MARINE...TITUS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
550 AM EST THU DEC 29 2011 .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A STRONG WRLY MID/UPPER LEVEL FLOW INTO THE PAC NW AND WNW FLOW DOWNSTREAM FROM THE SRN CANADA AND NRN PLAINS INTO THE GREAT LAKES. ONE SHEARED SHORTWAVE TROUGH WAS LOCATED NORTH OF LAKE SUPERIOR AND ANOTHER WAS MOVING THROUGH SW MN. AT THE SFC...A 997 MB LOW WAS LOCATED OVER SRN MN RESULTING IN S TO SE WINDS ACROSS UPPER MICHIGAN. AN AREA OF SNOW FROM NE MN INTO WRN LAKE SUPERIOR NW WI WITH VSBYS INTO THE 1-3SM RANGE WAS SUPPORTED BY 285K-290K ASCENT AHEAD OF A 850-700 MB TROUGH. ANY LAKE EFFECT/ENHANCED SNOW OFF OF LAKE MICHIGAN WITH THE SRLY FLOW HAS BEEN MINIMAL WITH ONLY A DUSTING AT MOST. && .DISCUSSION... TODAY AND TONIGHT...EXPECT THE AREA OF SNOW TO PROGRESS ACROSS UPPER MICHIGAN TODAY. MODELS CONSENSUS QPF OF AROUND A TENTH OF AN INCH WITH SNOW/WATER RATIO VALUES NEAR 15/1 WOULD RESULT IN SNOWFALL AMOUNTS OF AN INCH OR TWO WHICH IS REASONABLE GIVEN 2G-3G/KG MOISTURE AVBL NEAR 700MB DURING A 6 HOUR PERIOD OF STRONGER LIFT. UNCERTAINTY REMAINS WITH REGARD TO LAKE ENHANCED SNOW POTENTIAL INTO THE SE CWA. THE HIGHER RES MODELS HAVE BEEN OVERDOING PCPN WITH BANDS OFF OF LAKE MICHIGAN SO FAR. HOWEVER...AS THE DEEPER MOISTURE ARRIVES...EXPECT THAT THE LAKE CONTRIBUTION MAY ADD AN ADDITIONAL 1-2 INCHES TO SNOWFALL AMOUNTS. SINCE THE WINDS WERE BACKING MORE SERLY AHEAD OF THE LOW...THE BEST LOW LEVEL CONV AND OVER WATER TRAJECTORIES HAVE SHIFTED TO THE WEST. SO...HAVE CANCELLED THE ADVY FOR LUCE COUNTY AND CONTINUED MENTION OF 2 TO 4 INCHES OF SNOW IN THE ADVY FOR SCHOOLCRAFT COUNTY TODAY. MODELS SUGGEST THAT THE DEEPER MOISTURE WILL QUICKLY DEPART THIS AFTERNOON OVER THE WEST. HOWEVER...LACK OF LOW LEVEL LIFT OR FOCUSING MECHANISM SHOULD MINIMIZE POTENTIAL FOR -FZDZ. SOME LIGHT SNOW WILL LINGER OVER THE ERN CWA TONIGHT AS THE SFC-850 MB TROUGH SLOWLY PIVOTS TO THE NORTHEAST. FRIDAY...MODELS WERE IN AGREEMENT THAT THE PCPN ASSOCIATED WITH A SHORTWAVE MOVING FROM THE PAC THROUGH THE NRN PLAINS INTO THE MS VALLEY AND SRN GREAT LAKES IS EXPECTED TO REMAIN SOUTH OF UPPER MI. SOME ISOLATED LIGHT SNOW SHOWERS MAY BE POSSIBLE NEAR AN INVERTED TROUGH AXIS INTO THE NRN CWA. AGAIN...-FZDZ MAY ALSO BE POSSIBLE BUT PROBABILITIES REMAIN LOW. SAT INTO SUN...THE NEXT MID LEVEL TROUGH IN THE PROGRESSIVE PATTERN WILL MOVE INTO THE REGION BY LATE SAT. WAA AHEAD OF THE MID LEVEL AND SFC TROUGH MAY BRING SOME LIGHT PCPN INTO THE WRN CWA. THE MORE CONSISTENT ECMWF WAS PREFERRED FOR DETAILS WITH THE SYSTEM AS THE GFS AND NAM HAVE AT TIMES SHOWED A STRONGER SHORTWAVE SWEEPING THROUGH THE REGION THAT WOULD GENERATE SUBSTANTIAL PCPN AND BRING MUCH GREATER DEEPENING OF THE SFC LOW. FALLING TEMPS AND BLUSTERY WNW WINDS ARE EXPECTED BY SUN AFTERNOON BEHIND A STRONG COLD FRONT. SUN NIGHT INTO TUE...AS THE PATTERN BRIEFLY AMPLIFIES...MUCH COLDER AIR WILL POUR INTO THE WRN LAKES ON NW TO N WINDS DROPPING 850 MB TEMPS TO AROUND -20C. SUBTLE MODEL DIFFERENCES REMAIN WITH THE PREVAILING WIND DIRECTION AS THE GFS REMAINS MORE TO THE NW COMPARED TO THE NRLY DIRECTION DEPICTED BY THE ECMWF/GEM. SIGNIFICANT LES REMAINS POSSIBLE WITH INTENSITY DROPPING OFF MON AS DEEPER MOISTURE DEPARTS. && .AVIATION /FOR THE 06Z TAF ISSUANCE/... AS NEXT LOW PRES SYSTEM APPROACHES FROM THE W...-SN WILL SPREAD ACROSS THE AREA OVERNIGHT THRU THE MORNING...RESULTING IN VFR CONDITIONS AT KIWD/KCMX/KSAW FALLING QUICKLY TO MVFR THEN IFR. LIFR CONDITIONS ARE POSSIBLE AS WELL...ESPECIALLY AT KCMX...DURING PERIOD OF HEAVIEST SNOW. IMPROVEMENT EXPECTED W TO E LATE MORNING/AFTN AS MAIN AREA OF -SN EXITS. HOWEVER...IT MAY BE DIFFICULT TO GET RID OF THE LOWER CIGS GIVEN LIGHT LOW-LEVEL WINDS AND THUS WEAK ADVECTION OF ANY DRIER AIR AT THE LOW-LEVELS. SO... CIGS MAY REMAIN IFR OR ONLY RISE SLIGHTLY TO LOW MVFR IN THE AFTN. && .MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/... A LOW PRESSURE SYSTEM OVER MN WILL MOVE EAST TODAY. ALTHOUGH WINDS SHOULD STAY BELOW GALE FORCE...THEY WILL BECOME RATHER GUSTY OUT OF THE SOUTHEAST WITH PERHAPS A GUST OR TWO CLOSE TO GALE FORCE. AFTER ANOTHER LOW MOVES ACROSS THE LOWER LAKES ON FRIDAY...A WEAK RIDGE BUILDS ACROSS LAKE SUPERIOR INTO SATURDAY BEFORE A STRONG LOW DEVELOPS OVER THE PLAINS AND MOVES NORTH OF LAKE SUPERIOR FOR NEW YEARS DAY. HIGH END NORTH-NORTHWEST GALES ARE POSSIBLE WITH THIS SYSTEM INTO MONDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ014- 085. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SYNOPSIS...JLB DISCUSSION...JLB AVIATION...ROLFSON MARINE...TITUS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
930 AM CST THU DEC 29 2011 .DISCUSSION...FORECAST CHALLENGE FOR UPDATE CONCERNS PCPN CHANCES/PHASE AND TEMPERATURES. CLEARING AND MODEST SNOW COVER ALLOWED TEMPERATURES TO DROP WELL IN THE SINGLE DIGITS ACROSS THE NORTHERN VALLEY THIS MORNING. CLOUDS WILL SPREAD ACROSS THE REGION TODAY HOWEVER WARM ADVECTION ACROSS FAR NORTH WILL BE LIMITED. FOR THIS WILL NEED TO LOWER MINIMUMS A BIT ACROSS THE FAR NORTH. PCPN INITIATION AND PHASE WILL BE BIG CHALLENGE LATE THIS AFTERNOON AND EVENING. WITH VERY LITTLE NEW DATA TO LOOK AT WILL NOT BE ALTERING POPS/WEATHER FOR UPDATE. RUC DOES INDICATE MOST PCPN MAY HOLD OFF TILL AFT 00Z HOWEVER NOT PICKING UP ON NARROW BAND ACROSS WESTERN ND. PREFER TO SEE NEW MODEL DATA BEFORE MAKING ANY CHANGES. && .AVIATION...VERY CHALLENGING FORECAST AND CONFIDENCE IS LOW. THERE WILL LIKELY BE A PERIOD OF VFR CIGS OR CLEAR SKIES DURING THE MORNING HOURS AND INTO THE AFTERNOON HOURS. HOWEVER...THERE IS A DEVELOPING AREA OF LOW CIGS NORTH OF THE INTERNATIONAL BORDER...AND NOT SURE WHAT IS GOING TO HAPPEN WITH THESE (COULD CONTINUE TO GROW SOUTHWARD). IFR/MVFR CIGS (VSBY WITH -SN) WILL APPROACH THE REGION DURING THE AFTERNOON HOURS AND CONTINUE INTO THE EVENING HOURS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ VOELKER
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1016 AM EST THU DEC 29 2011 .SYNOPSIS... A PAIR OF ALBERTA CLIPPERS WILL MOVE ACROSS THE GREAT LAKES TODAY AND FRIDAY. A STRONG ARCTIC COLD FRONT IS LIKELY TO MOVE THROUGH THE STATE ON NEW YEARS DAY. GUSTY WINDS...BITTERLY COLD AIR AND LAKE EFFECT SNOW ARE EXPECTED AS THE COLD AIR RUSHES IN ACROSS THE LAKES. && .NEAR TERM /UNTIL 5 PM THIS AFTERNOON/... RETURN FLOW WEST OF THE BOUNDARY LAYER RIDGE AXIS IS TOUCHING OFF SOME VERY LIGHT PRECIP IN THE FORM OF SNOW OVER SOUTHWEST PA THIS MORNING. MOST HIGH RESOLUTION LCL MODELS AND OPERATIONAL GFS/NAM AND RUC HAVE NOT CAPTURED THIS...BUT LCL HRR AT LEAST HAS SOME QPF PAINTED OVER WESTERN PORTIONS OF THE LAUREL HIGHLANDS BETWEEN 14Z AND 16Z BEFORE DISSIPATING IT. TRACE AMOUNTS FROM FLURRIES SHOULD BE INCONSEQUENTIAL THIS MORNING...BUT DID ADD SLIGHT CHC POPS FOR THIS ALONG MY AREAS BORDERING KPBZ OVER THE LAUREL HIGHLANDS AND FURTHER NORTH INTO THE NORTH CENTRAL MOUNTAINS. AS UPPER SHORT WAVE DIVES DOWN OVER IA/WI EARLY THIS MORNING AND TOWARDS THE OHIO VALLEY THIS AFTERNOON...A MAIN AREA OF WARM ADVECTION PRECIPITATION WILL BREAK OUT ACROSS IL/OH AND CROSS INTO PA LATE THIS AFTERNOON. OTHER THAN FLURRIES THIS MORNING INTO THIS AFTERNOON SOUTHWEST...WEST AND NORTH...PRECIPITATION FROM THE MAIN WAVE WILL HOLD OFF UNTIL AFTER 22Z. HIGHS WILL BE A DEG OR TWO COOLER IN THE SE WITHOUT THE DOWNSLOPE AND LESS SUNSHINE TODAY VS WED. TEMPS IN THE N WILL BE 5-7F BETTER THAN WED DUE TO THE SRLY WIND/WAA. && .SHORT TERM /5 PM THIS AFTERNOON THROUGH SATURDAY/... WNW UPPER FLOW IS FAST WITH A 110KT JET STREAK FORCING THE LIFT TO IT/S LEFT EXIT REGION...AND WILL MOVE JUST TO THE SOUTH OF THE AREA BY MIDNIGHT. THE FLOW FLATTENS OUT A BIT AS THE MAIN WARM ADVECTION MOVES OVER OUR NRN ZONES AND NY STATE THIS EVENING AND OVERNIGHT. WILL RUN WITH ONLY HIGH CHC/LOW LIKELY POPS FOR THE NRN TIER TONIGHT...AS PRECIP MAY NOT BE HEAVY ENOUGH TO MAKE ACCUMS OF MORE THAN AN INCH THERE. POPS/CHC FOR SNOW FALL OFF PRETTY QUICKLY TO THE SOUTH OF ROUTE 6 AND ARE SMALL BY THE TIME YOU REACH I-80. TEMPS WILL PROBABLY FALL JUST A FEW DEGS FOR THE NIGHT WITH THE CLOUDS AND SOME S WIND. NEXT SHORT WAVE/CLIPPER WRAPS UP A BIT MORE THAN THE FIRST ONE...WITH A MORE COHERENT TROUGH BEGINNING TO FORM OVER THE UPPER MIDWEST ON FRI. SFC LOW DEEPENS NEAR 1000MB AS IT MOVES OVER LOWER MI AND THE LOWER LAKES. THIS STORM WILL SPREAD ADDITIONAL MOISTURE IN VERY QUICKLY ON FRIDAY AND ALLOW ONLY A BRIEF PERIOD OF FAIR WEATHER IN THE MORNING. HOWEVER...WITH WARM AIR OVERRUNNING THE COLD AIR AT THE SFC...SOUNDING PROFILES INDICATE AT LEAST SOME THREAT FOR PATCHY FREEZING DRIZZLE OR BRIEF FREEZING RAIN ACROSS MAINLY THE NORTHERN VALLEYS EARLY FRI MORNING. DO NOT EXPECT ENOUGH COVERAGE TO GARNER AN ADVISORY AT THIS TIME...BUT DID ADD THIS TO THE HWO. POPS WILL BE HIGHER FRI THAN THURS...BUT THE TEMPS WILL RISE ENOUGH AHEAD OF THIS PSEUDO CLIPPER TO MAKE MAINLY RAIN AFT 9 AM SOUTH OF I80. QPF WILL BE VERY LIGHT...THOUGH. NRN MTS COULD SEE MOSTLY SNOW BUT WAA WORKS TEMPS HIGHER THERE AS WELL...BUT THE COLD AIR WILL BE TOUGHER TO SCOUR OUT. WILL KEEP ANY MENTIONS OF ACCUMS IN THE NCENT COS. MAXES ON FRI WILL TRY TO GET INTO THE L50S IN THE S...BUT COULD STICK IN THE L-M 30S IN THE FAR NRN VALLEYS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AFTER A BREAK ON SATURDAY...A STRONG ARCTIC COLD FRONT WILL BULLY ITS WAY THROUGH THE AREA DURING NEW YEARS DAY. THIS FEATURE WILL DEFINE THE LEADING WEDGE OF SOME MUCH COLDER AIR THAT WILL BRING THE PUFFY COATS BACK OUT OF THE CLOSET FOR AT LEAST A FEW DAYS. THE UPPER PATTERN WILL BECOME HIGHLY AMPLIFIED FOR THE FIRST FEW DAYS OF THE NEW YEAR WITH THE AXIS OF THE TROUGH SWINGING RIGHT THROUGH THE GREAT LAKES REGION. LONG TERM GUIDANCE COMING INTO LINE WITH SIMILAR IDEAS ON MUCH COLDER AIR FROM MONDAY THROUGH MID WEEK. -20C 850 TEMPS OVER THE STATE WOULD KEEP TEMPS AROUND THE 20 DEGREE MARK...GIVE OR TAKE A FEW DEPENDING ON CLOUD COVER. SAVE FOR ANY CLIPPER TYPE SYSTEMS THAT MAY ENTER THE PICTURE IN THIS DEEP TROUGH...LAKE EFFECT HOLD THE LIMITED CHANCE FOR SNOWFALL DURING THIS PERIOD. THE EURO MODEL STILL DEVELOPS A STORM SYSTEM AS THIS COLD POOL MOVES OVER THE GULF STREAM BUT DOES SO WELL EAST OF THE SOLUTION FROM 24 HOURS AGO...FAR OUT TO SEA. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... MVFR CIGS LINGERING IN HIGHER ELEVATIONS OF THE NW MTNS...WITH VFR ELSEWHERE AT 12Z. CIGS WILL LIFT TO VFR AREAWIDE BY 14-15Z AS WINDS TURN TO THE SOUTH AT AROUND 5 MPH FOR THE DAYLIGHT HOURS. SHORTWAVE/CLIPPER SLIDES IN FROM THE WEST EARLY THIS EVENING...SPREADING LOWER CIGS AND LIGHT SNOW BACK INTO MAINLY HIGHER TERRAIN OF THE WEST BY EARLY EVENING...WHILE REMAINDER OF THE AREA IS PRIMARILY VFR. INCREASING LOW LEVEL WINDS WHICH WILL LEAD TO MARGINAL WIND SHEAR AT BFD AND JST OVERNIGHT. A SLIGHTLY BETTER CHC OF SNOW OR RAIN SHOWERS FRI...AS A SECOND CLIPPER SYSTEM MOVES THROUGH. OUTLOOK... FRI...MVFR/IFR MAINLY WESTERN AREAS WITH RAIN/SNOW SHOWERS. SAT...MVFR NW MTNS. VFR ELSEWHERE. SUN...MAINLY VFR. SUN NIGHT-MON...MVFR POSS IN -SHSN. GUSTY WINDS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO NEAR TERM...DANGELO/DEVOIR SHORT TERM...DANGELO/DEVOIR LONG TERM...TYBURSKI AVIATION...RXR
AREA FORECAST DISCUSSION...UPDATED
NWS MORRISTOWN TN
937 AM EST THU DEC 29 2011 .DISCUSSION... THE POSITION OF THE JET STREAM OVER THE UPPER MS VALLEY TO OHIO VALLEY IS BRINGING CONSIDERABLY CLOUDINESS TO NORTHERN PORTIONS OF THE AREA THIS MORNING. RUC AND NAM SHOW DECREASING CLOUD COVER THROUGH THE AFTERNOON...BUT THE MORNING CLOUDS ARE KEEPING TEMPERATURES LOWER THAN FORECAST SO FAR. WILL ISSUE AN UPDATE TO ADJUST TEMPERATURES DOWNWARD IN THE NORTH...AND INCREASE CLOUD COVER AS WELL. && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DGS
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1220 PM EST THU DEC 29 2011 .AVIATION... / 18Z TAFS / KIWX RADAR STILL INDICATING A FEW LIGHT SHOWERS/SPRINKLES MOVING TOWARD THE KFWA AREA...NOT ANTICIPATING ANY VSBY OR CEILING RESTRICTIONS WITH THIS SO WILL LEAVE OUT OF TAF TO BEGIN THE PERIOD. GUSTY SOUTHWEST WINDS THIS AFTERNOON OTHERWISE VFR CONDITIONS TO PREVAIL AT BOTH SITES UNTIL FRIDAY MORNING WHEN -RA WITH NEXT CLIPPER SYSTEM EXPECTED TO ARRIVE AND BRING WITH IT MVFR CIGS/VSBYS. && .PREV DISCUSSION... /ISSUED 355 AM EST THU DEC 29 2011/ SHORT TERM... / TODAY THROUGH FRIDAY NIGHT / 08Z SFC ANALYSIS SHOWS A SFC LOW NEAR MSP WITH A WARM FRONT EXTENDING SE INTO EASTERN IA AND WC IL. THE ASSOCIATED LOW AMPLITUDE SHORTWAVE OVER THE UPPER MIDWEST WILL SHEAR OUT TOWARDS THE CENTRAL GREAT LAKES TODAY ALLOWING THE WARM FRONT TO SURGE NEWD INTO THE SRN GREAT LAKES. RATHER MODEST OVERRUNNING/ISENTROPIC UPGLIDE EXPECTED JUST AHEAD OF THIS WARM FRONT THIS MORNING INTO EARLY THIS AFTERNOON (40 KNOTS OF CROSS ISOBARIC FLOW ON THE I290 SFC). UPSTREAM OBS/MOSAIC RADAR AND THE BULK OF 00Z GUIDANCE SUGGEST THAT NORTHERN AREAS MAY SEE A BRIEF PERIOD (AN HOUR OR TWO) OF VERY LIGHT PCPN THIS MORNING INTO EARLY THIS AFTN...WITH THE BETTER CHANCES FOR MEASURABLE PCPN (A COUPLE HUNDREDTHS AT BEST) BEING ACROSS THE NORTH/NORTHEAST WITH MAINLY VIRGA SOUTHWEST. LATEST RUC SOUNDINGS AND SFC OBS CONTINUE TO SUPPORT A POSSIBLE LIGHT MIX OF FREEZING DRIZZLE/SNOW TO START...LIKELY TRANSITIONING TO A BRIEF PERIOD OF DRIZZLE. ANY FREEZING DRIZZLE/RAIN BTW 12-15Z MAY CREATE A FEW SLICK SPOTS ON AREA ROADS...MAINLY NORTH OF ROUTE 6. OTHERWISE...EXPECT WINDS WILL PICK UP AND VEER BEHIND THE FRONTAL BOUNDARY WITH GUSTS OF 20-25 KNOTS POSSIBLE. A MUCH MORE VIGOROUS SHORTWAVE NOW ACROSS THE PAC NW WILL DIG INTO THE MID MS VALLEY AND NRN OH VALLEY BY LATER TONIGHT AND FRIDAY. GFS/ECMWF AGREE ON 120-140 METER 500 MB HEIGHT FALLS WITH THIS FEATURE SUPPORTING A RATHER HEALTHY LOW LVL RESPONSE AND THETA-E ADV INTO THE AREA WITH PCPN FOCUSING ALONG A DEEPENING BAROCLINIC ZONE. A MODEL CONSENSUS FAVORS THE NORTHERN HALF OF THE FA FOR BEST CHANCES FOR MEASURABLE RAINFALL. AMOUNTS ARE FCST TO RANGE BETWEEN 0.20" AND 0.50" HERE. HIRES GUIDANCE IS A LITTLE FARTHER SOUTH WITH THE TRACK OF THIS SYSTEM SO DID CONTINUE WITH CHC/SLIGHT WORDING FOR SNOW IN THE FAR NORTH...WITH AREAS JUST NORTH OF THE FA IN A GOOD POSITION FOR A MODERATE SNOWFALL. OTHERWISE...TEMPS ARE FCST TO BE ABOVE NORMAL THIS PERIOD WITH ONLY MINOR TWEAKS MADE. LONG TERM... OVERALL LARGE SCALE PATTERN STILL EXPECTED TO BECOME MORE AMPLIFIED THROUGH THE LONG TERM WITH BRIEF ARCTIC INTRUSION STILL EXPECTED LATTER HALF OF WEEKEND INTO NEXT WEEK. MEDIUM RANGE MODELS REMAIN IN GOOD AGREEMENT ON LARGE SCALE WITH DIFFERENCES CONTINUING IN THE DETAILS. CR ALLBLEND LOADED AND COLLABORATED SOME TWEAKS TO TEMPS AND POPS. A QUIET START EXPECTED ON SATURDAY WITH WARM AIR ADVECTION AHEAD OF FIRST COLD FRONT AND TEMPERATURES RISING WELL ABOVE NORMAL FOR LATE DECEMBER. SHOULD SEE 40S ACROSS ENTIRE AREA FOR HIGHS WITH 50S NOT OUT OF QUESTION SOUTH AND WEST. WARM AIR ADVECTION CONTINUES FIRST HALF OF SATURDAY NIGHT WITH TEMPS STEADY OR SLOWLY RISING UNTIL INITIAL FRONTAL PASSAGE LATE. HAVE TRIED TO DETAIL THIS SCENARIO IN HOURLY GRIDS WITH STEADY TEMPS THROUGH 06Z THEN A SLOW FALL TOWARD 12Z. DETAIL DIFFERENCES AND COMPLICATIONS IN FORECAST BEGIN IN THIS SATURDAY NIGHT INTO SUNDAY TIME FRAME WITH STRENGTH AND TIMING OF COLD AIR ADVECTION AND ANY ASSOCIATED PCPN. 850MB TEMPS BEGIN TO FALL AFTER 06Z SUNDAY WITH 1000-850MB THICKNESSES FOLLOWING. MODELS SHOWING LITTLE IN WAY OF PCPN WITH THIS FRONT GIVEN POSITIVELY TILTED UPPER SYSTEM AND NO STRONG MOISTURE SURGE AHEAD OF IT. DEEPENING SURFACE LOW REMAINS WELL NORTH OF AREA WITH ONLY SUBTLE INDICATIONS OF SECONDARY LOW DEVELOPMENT ALONG FRONT BY A FEW MODELS. HAVE THEREFORE ALLOWED LOW CHANCE POPS TO RIDE SAT NIGHT AND SUNDAY MORNING. SUNDAY BEGINNING TO LOOK DRY IN WAKE OF INITIAL COLD FRONT WITH SOME SUNSHINE EVEN POSSIBLE IN DRY SLOT BEFORE SECONDARY ARCTIC FRONT LATER IN THE DAY. IF THIS OCCURS...FALLING TEMPS EARLY IN THE MORNING MAY BECOME STEADY OR EVEN RISE A FEW DEGREES BEFORE SECONDARY FRONT BRINGS MUCH COLDER AIR IN DURING THE AFTERNOON. FOR NOW HAVE CHOSEN TO GO WITH SLOWLY FALLING TEMPS DURING THE DAY GIVEN TEMPS LOOK TO FALL IN THE AFTERNOON REGARDLESS. WITH ARCTIC INTRUSION SUNDAY NIGHT WILL SEE BEST LAKE EFFECT SNOW POTENTIAL OF THE SEASON AS DELTA T VALUES CLIMB WITH SURFACE TO 850MB WELL INTO LOWER 20S. SURFACE TO 700MB DELTA T VALUES REACH CRITICAL 30C THRESHOLD WHICH IS A GOOD INDICATOR OF HEAVY SNOW POTENTIAL. LIMITING FACTOR CONTINUES TO BE MOISTURE PROFILES BUT MEDIUM RANGE MODELS ARE SHOWING SOME DECENT SYNOPTIC MOISTURE LATE SUNDAY NIGHT THROUGH MONDAY WHICH WOULD SUPPORT A PERIOD OF HEAVY LAKE EFFECT SNOW BANDS. NORTHWEST FLOW AND WIND FIELD SUGGEST MULTI-BANDED EVENT WHICH MAKES PINNING DOWN AMOUNTS AND LOCATIONS DIFFICULT AT THIS TIME PROJECTION. HAVE BUMPED NW FETCH FAVORED AREAS INTO LIKELY CATEGORY FOR NOW. HEADLINES POSSIBLE LATER THIS WEEKEND INTO EARLY NEXT WEEK AS MOISTURE PROFILES BECOME BETTER DEFINED BY HIGHER RESOLUTION MODELS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...STEINWEDEL LONG TERM...LASHLEY AVIATION...LOGSDON
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1158 AM CST THU DEC 29 2011 .AVIATION... CURRENTLY LOW PRESSURE IS SLIDING SOUTHEASTWARD ACROSS SOUTHERN WISCONSIN WITH IFR CEILINGS OVER CENTRAL MINNESOTA. VFR CONDITIONS ARE IN PLACE OVER EASTERN IOWA. IFR CEILINGS IN CENTRAL MINNESOTA ARE FORECAST TO REMAIN TO THE NORTH AND EAST OF KCID...KDBQ...KMLI...AND KBRL THIS AFTERNOON. CLOUD HEIGHTS WILL SLOWLY LOWER AS ANOTHER FAST MOVING STORM SYSTEM APPROACHES AND MOVES THROUGH THE REGION TONIGHT. RAIN IS EXPECTED TO DEVELOP BY 06 UTC WITH MVFR CEILINGS AT KCID...KDBQ...AND KMLI. KMLI IS ON THE SOUTHERN EDGE OF THE HEAVIER PRECIPITATION SO WENT WITH VCSH AFTER 14 UTC. CURRENTLY...RAIN IS EXPECTED TO TRANSITION TO SNOW AT KDBQ AFTER 12 UTC. ANY LINGERING PRECIPITATION WILL EXIT INTO WESTERN ILLINOIS BY 18 UTC WITH MVFR CEILINGS CONTINUING THROUGH 18 UTC AT ALL TAF SITES. ..JH/DC.. && PREV DISCUSSION... /ISSUED 652 AM CST THU DEC 29 2011/ UPDATE... A FEW SHRA/S HAVE DEVELOPED FROM NEAR QUAD CITIES S/E WITHIN AREA OF MID LEVEL INSTABILITY AHEAD OF VORT MAX. UPDATED TO ADD ISOLD MENTION AND SHOULD BE OUT OF CWA NEXT 1-2 HRS. NEXT CONCERN IS CLOUD TRENDS. LEADING EDGE OF STRATUS HAS DISSIPATED OVER SOUTHERN MN AND NOTICING PAST FEW HRS OF CIG TRENDS FROM RUC BACKUP MODEL KEEPS LOW CLOUDS TO N/W OF CWA TDY. THIS LOOKS REASONABLE GIVEN RECENT TRENDS PLUS THE ADDITIONAL RAPID EROSION TO STRATUS OVER ND DUE TO WARM ADVECTION ALOFT. WILL BE UPDATING TO BE MORE OPTIMISTIC WITH SKY COVER NORTH HALF AND TWEAK MAXES UP A COUPLE DEGS. PREV DISCUSSION... /ISSUED 411 AM CST THU DEC 29 2011/ SYNOPSIS... STARTING OUT THIS AM WITH TEMPS THAT ALREADY AT OR 5+ DEGS ABOVE NORMAL HIGHS. ALWAYS A GREAT SIGN AND HARBINGER OF WHAT IS TO COME TDY. QUASI-ZONAL FLOW FULL OF ENERGY EARLY THIS AM. WATER VAPOR IMAGERY AND PROFILERS DEPICT SHORTWAVE NEAR PICKLE LAKE ONTARIO (CYPL) WITH SECONDARY WAVE FURTHER SOUTH NEAR LACROSSE WI... BOTH SLIDING E/SE. ATTENDANT SFC LOW WAS LOCATED CLOSE TO SAINT CLOUD MN WITH COLD FRONT EXTENDING WNWD INTO NORTHERN SD WHILE WARM FRONT WAS DRAPED SEWD INTO EASTERN IA. WARM ADVECTION WING WITH JUST TRACE AMOUNTS OF PCPN PASSING QUICKLY THROUGH NORTHERN IL. MOST OBS THIS FAR SOUTH HAVE BEEN REPORTING SPRINKLES BUT A COUPLE OF QUESTION MARKS SHOWING ON SOME ASOS NEAR WI/IL BORDER INTO SOUTHERN WI AND SO CANT RULE OUT SOME FLAKES OR EVEN ICE PELLETS BUT NO GROUND TRUTH REPORTS. THIS WILL BE EXITING SHORTLY WITH SKIES CLEARING INTO EASTERN IA IN WAKE OF WARM ADVECTION. SATL SHOWS A LARGE AREA OF LOW CLOUDS OVER ND... FAR NORTHEAST SD AND WESTERN MN ON BACKSIDE OF SFC LOW IN LOW LEVEL COLD ADVECTION WHICH HAVE BEEN SLIDING SEWD. MEANWHILE... NEXT BARRAGE OF ENERGY IN VERY ENERGETIC PACIFIC WAVE TRAIN PLOWING THROUGH PACIFIC NW AND NORTHERN ROCKIES... AND ITS THIS ENERGY THAT WILL AID IN BRINGING PCPN TO PORTIONS OF THE REGION TNGT-FRI. SHORT TERM...TODAY AND TONIGHT... EYES ARE POINTED NW EARLY THIS AM. SFC LOW OVER CENTRAL MN TO DIVE E/SE THROUGH SOUTHERN WI TDY WITH TRAILING COLD FRONT SWEEPING ACROSS THE CWA. THUS... WARM ADVECTION ON GUSTY SW WINDS TO START OFF WILL EVENTUALLY BE REPLACED WITH COLD ADVECTION ON GUSTY W/NW WINDS. BEST COLD ADVECTION PROGGED NORTH THIRD TO HALF OF CWA WHERE ALSO EXPECT TO SEE SOME STRATUS TURNING SKIES FROM SUNNY TO PT-MOCLDY. TEMPS EVERYWHERE WELL ABOVE NORMAL BY CLOSE TO 15+ DEGS... WITH COOLEST READINGS NORTH WHERE WENT WITH AROUND 40/L40S DUE TO ANTICIPATION OF LOW CLOUDS BY MID-LATE AM. FROM THERE ON SOUTH TEMPS WARMING WELL INTO THE 40S WITH 50S OVER SE IA... WCNTRL IL AND NE MO. TNGT... ANOTHER DOUBLE BARREL ENERGY COMPLEX EXPECTED TO SHIFT FROM THE PLAINS INTO UPPER MIDWEST. ROBUST WARM ADVECTION TO GENERATE PCPN THAT WILL MOVE ACROSS MUCH OF AREA BY MID-LATE EVE AND OVRNGT ESPECIALLY NORTH OF KOTM-KBRL LINE. FCST SOUNDINGS AND LATEST SUITE OF SREF PTYPE PROBS ALL SUPPORT PCPN WILL BE RAIN. UKMET AND ECMWF STRONGER WITH ENERGY RESULTING IN DEEPER SFC LOW FOR EVEN WARMER DRAW AGAIN SUPPORTING RAIN AS THEY SHOW H85 LOW MOVING INTO NE IA 12Z FRI... PLACING BETTER SNOW CHCS NORTH OR LEFT OF THE H85 LOW TRACK. QPF AMOUNTS WILL BE LIGHT AND GENERALLY A TENTH OR TWO AT MOST. TEMPS WILL DROP OFF A BIT EARLY THIS EVE THEN BECOME STEADY AND SLOWLY RISE WITH ONSET OF LOW LEVEL WARM ADVECTION. ..05.. LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY... FRIDAY...STILL SOME VARIANCE BETWEEN THE 00Z MODEL RUNS INTO FRI WITH HANDLING AND DEVELOPMENT OF THE PASSING WAVE COMPLEX. BUT WITH THE PROGRESSIVE NATURE OF THE CURRENT REGIME PATTERN WE HAVE BEEN IN THIS WEEK AND LOOKING AT UPPER JET DYNAMICS THROUGH FRI NIGHT... FEEL THE 00Z RUN GFS SOLUTION THE ONE TO FOLLOW FOR NOW THIS PERIOD. ALSO PREFER THE FURTHER NORTH LOW TO MID LEVEL WAVE PROGRESSION ACRS THE REGION IN LINGERING POSITIVE AO. THIS ACCEPTED GFS SOLUTION SUGGESTS BULK OF ANY PRECIP SHIELD ASSOCIATED WITH THE PASSING LOW WILL BE ON THE MOVE OUT OF THE DVN CWA FRI MORNING AFTER 12Z. WILL WALK OUT PRECIP IN THE MORE WITH LIKELY POPS IN THE FAR NORTHEAST... AND LESSER CHC POPS FURTHER TO THE WEST AND SOUTH. IT ALSO APPEARS IN-WRAPPING LLVL COLD CONVEYOR OR TOP-DOWN COOLING ENOUGH FOR A CHANGE OVER TO SNOW WILL OCCUR AFTER THE BULK OF ANY MEASURING PRECIP EXITS THE AREA AS WELL. BUT PROJECTED THERMAL PROFILES ARE CLOSE THROUGH 15Z FRI ALONG AND NORTH OF THE HWY 20 CORRIDOR AND WILL MENTION A MIX IN THOSE AREAS BUT WITH LITTLE IF ANY SNOW ACCUM. LOW TO MID LEVEL DRYING/RH DECREASE LATE MORNING THOUGH MIDDAY AS LOW CENTER PASSES...THEN SYSTEM WRAP AROUND STRATOCU ENGULFS MUCH OF THE CWA FRI AFTERNOON INTO THE EVENING. EXTENT OF PRECIP POTENTIAL IN THIS WRAP AROUND DECK UNCERTAIN ALONG WITH ADEQUATE MOISTURE DEPTH FOR MEASURABLE. FOR NOW WILL JUST GO WITH A SLIGHT CHC OF LIGHT RAIN OR LIGHT SNOW IN THE FAR NORTH FRI AFTERNOON...BUT IT MAY BE NOT MUCH MORE THAN FLURRIES OR SPRINKLES. FRI HIGHS RANGING FROM AROUND 40 IN THE FAR NORTH..TO NEAR 50 IN THE FAR SOUTH. THEN EXPECT THE CLOUDS TO CLEAR TO THE EAST FRI NIGHT WITH SFC WIND DROP OFF WITH PASSING SFC RIDGE LOBE. LOWS IN THE UPPER 20S TO LOWER 30S FOR NOW BUT IT MAY BE COOLER DEPENDING ON IF RETURN FLOW CAN COMMENCE TOWARD SAT MORNING IN TIME TO HALT THE TEMP DROP-OFF ESPECIALLY WEST OF THE MS RVR. SATURDAY AND SUNDAY...LOOKING AT THE LATEST 00Z RUN MEDIUM RANGE MODELS AND WARM UP POTENTIAL AHEAD OF A SUBSTANTIAL IMPULSE TRYING TO PHASE OVER THE MID CONUS ON SAT...DURATION OF THE WARM TONGUE AND MIXING DEPTH STILL AT QUESTION ENOUGH TO FUEL THE ADVERTISED DAY WELL IN THE 50S. WILL MAKE ONLY MINOR ADJUSTMENTS TO SAT HIGHS FOR NOW AS STILL SOMEWHAT HESITANT TO GO CRAZY WITH THE FULL WARM UP POTENTIAL. BUT EVEN WITH THE CURRENT PROJECTED THERMAL PROFILES AND FCST SOUNDINGS...JUST MIXING UP TO AROUND H9 MB/INTO BASE OF A VERY PRONOUNCED WARM WEDGE ALOFT/INVERSION CENTERED AROUND H85 MB...HIGHS WOULD BE IN THE MID 50S WITH A FEW LOCATIONS PUSHING THE UPPER 50S IN THE SOUTHWESTERN CWA. THE MODELS THEN REALLY START TO DIVERGE NEW YEARS EVE/SAT NIGHT WITH RESPECT TO CONTINUED DEVELOP OF A L/W TROF AND ASSOCIATED DEEPENING LLVL CYCLONE OVER THE UPPER MIDWEST AND NORTHWESTERN GRT LKS. BUT THE GENERAL ENSEMBLES SUGGEST THAT THE DVN CWA WILL REMAIN DRY SAT NIGHT AND MILD THROUGH MIDNIGHT/HELD UP WELL IN THE 40S BEFORE IN-SWIRLING COLD PUSH MAKES IT ACRS THE AREA FROM NW-TO-SE AFTER 09Z SUNDAY. STILL SOME DETAILS TO REFINE WITH THIS PERIOD OVER THE NEXT 24-36 HRS OF MODEL RUNS. AS FOR NEW YEARS DAY SUNDAY...A WINDY RAW DAY WITH MORNING HIGHS AND THEN FALLING TEMPS AS NORTHWEST SFC WINDS GUST OVER 30 MPH IN ROBUST CAA REGIME UNDER AMPLIFYING PATTERN. THE ECMWF STILL THE MOST DEVELOPED WITH HIGH AMPLITUDE NEAR MERIDIONAL FETCH DEVELOPING ACRS THE WESTERN GRT LKS BY MONDAY MORNING. H85 TEMPS BY 12Z MON IN NEGATIVE MID TEENS C AND LOWS SUNDAY NIGHT PROBABLY WELL DOWN IN THE TEENS DESPITE ONGOING MIXING WINDS OF 15-25 MPH EVEN AT NIGHT. WILL KEEP SUNDAY DRY BUT IN SUCH A REGIME WOULD EXPECT COL AIR STRATUS TO BLANKET THE AREA ALONG WITH SOME EMBEDDED FLURRIES. MONDAY THROUGH WEDNESDAY...WILL KEEP HIGH AMPLITUDE ARCTIC AIRMASS DUMP INTO THE MIDWEST GOING MON AND MON NIGHT. MONDAY HIGHS PROBABLY NOT TO GET OUT OF THE LOW TO MID 20S WITH ONGOING GUSTY NORTHWEST WINDS OF 20-30 MPH AND HIGHER GUSTS. SFC RIDGE LOBE SLIDING ACRS THE CWA...SFC WIND DECOUPLE AND STRATUS CLEAR OFF COULD FOSTER SINGLE DIGIT LOWS OVER SOME PORTIONS OF THE DVN CWA BY TUE MORNING EVEN OVER SNOWCOVER-LESS TERRAIN. AGAIN WILL GO DRY IN THE GRIDS ON MONDAY BUT WOULD BET SOME CAA FLURRIES CONTINUING TO GET MILKED OUT OF WHATEVER MOISTURE THERE IS ACRS THE AREA. LONGER RANGE SIGNALS SUGGEST THE FLOW WILL TRY TO FLATTEN OUT AGAIN TOWARD MID NEXT WEEK AS ARCTIC OSCILLATION/AO PROGS MIGRATE BACK TOWARD THE POSITIVE. BUT THERMAL MODERATION INTO TUE TO BE SLOW AND MORE REALIZED BY NEXT WED WITH HIGHS RETURNING TO THE MID AND UPPER 30S. THIS PROCESS MAY BE AIDED BY A WARM DRAW TO THE SOUTH OF CLIPPER TYPE SYSTEM DROPPING FROM SASKATCHEWAN TO WI SOMETIME DURING THIS TUE INTO WED PERIOD. ..12.. AVIATION... /ISSUED 1137 PM CST WED DEC 28 2011/ && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1244 PM EST THU DEC 29 2011 UPDATED AVIATION DISCUSSION FOR 18Z TAFS .UPDATE... LIGHT SNOW HAS SPREAD ACROSS THE AREA NORTH OF SFC LOW OVER SOUTHERN WI. SNOW HAS BEEN HEAVIER OVER SOUTH CENTRAL UPPER MICHIGAN AND ALSO OVER LK SUPERIOR OVR KEWEENAW PENINSULA. SO FAR...HIGHEST AMOUNTS WITH THE SYSTEM HAVE BEEN LESS THAN AN INCH. SE BLYR WINDS OFF LK MICHIGAN WILL CONTRIBUTE TO INCREASING LAKE ENHANCED SNOW FOR DELTA COUNTY AND SCHOOLCRAFT COUNTY THIS AFTN. NOT ALL THAT COLD AT H85 BUT INVERSION TOP TEMPS ARE SLIGHTLY COLDER...AROUND -8C...LEADING TO DELTA T/S AROUND 13C. SCNTRL UPR MI IS ALSO WHERE RUC INDICATES PERIOD OF H85 THETA-E ADVECTION TO ENHANCE THE SNOW. OPTED TO INCLUDE DELTA COUNTY IN SNOW ADVY FOR AFTN. TOTAL SNOW AMOUNTS WILL BE A STRETCH TO REACH 4 INCHES FOR THE AFTN...BUT TOTALS IN THE 2 TO 4 INCH RANGE WITH LOWER VSBY...DOWN TO 1/2SM IN HEAVIER SNOW...SEEMS TO JUSTIFY PUTTING DELTA INTO THE ADVY. EXPECT HEAVIER SNOW TO CEASE BY LATE AFTN OR EARLY EVENING AS BETTER THETA-E ADVECTION DIMINISHES TO THE EAST AS MAIN SHORTWAVE MOVES OUT OF THE AREA. OTHER SPOT TO WATCH WILL BE KEWEENAW AS SIMILAR SETUP IS PRESENT. SHEAR IN LOWEST 2KFT IS MORE NOTED WITH ESE WINDS AT SFC AND MORE SRLY WINDS TOWARD 925MB PER MQT VWP. HIGHER TERRAIN OF KEWEENAW COUNTY IS ORIENTED MORE WEST-TO-EAST SO WITH THE SOUTHERLY WINDS IN LOW-LEVELS THERE IS MORE OF AN UPSLOPE COMPONENT THERE COMPARED TO HOUGHTON COUNTY. COUNTY SHERIFF REPORTS A COUPLE INCHES THUS FAR OVR HIGHER TERRAIN. SINCE HEAVIER SNOW MAY LAST A FEW HOURS LONGER BASED ON STRONGER H85 THETA-E ADVECTION...WILL PUT ADVY UP FOR KEWEENAW COUNTY FOR THE AFTN. && .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A STRONG WRLY MID/UPPER LEVEL FLOW INTO THE PAC NW AND WNW FLOW DOWNSTREAM FROM THE SRN CANADA AND NRN PLAINS INTO THE GREAT LAKES. ONE SHEARED SHORTWAVE TROUGH WAS LOCATED NORTH OF LAKE SUPERIOR AND ANOTHER WAS MOVING THROUGH SW MN. AT THE SFC...A 997 MB LOW WAS LOCATED OVER SRN MN RESULTING IN S TO SE WINDS ACROSS UPPER MICHIGAN. AN AREA OF SNOW FROM NE MN INTO WRN LAKE SUPERIOR NW WI WITH VSBYS INTO THE 1-3SM RANGE WAS SUPPORTED BY 285K-290K ASCENT AHEAD OF A 850-700 MB TROUGH. ANY LAKE EFFECT/ENHANCED SNOW OFF OF LAKE MICHIGAN WITH THE SRLY FLOW HAS BEEN MINIMAL WITH ONLY A DUSTING AT MOST. && .DISCUSSION... TODAY AND TONIGHT...EXPECT THE AREA OF SNOW TO PROGRESS ACROSS UPPER MICHIGAN TODAY. MODELS CONSENSUS QPF OF AROUND A TENTH OF AN INCH WITH SNOW/WATER RATIO VALUES NEAR 15/1 WOULD RESULT IN SNOWFALL AMOUNTS OF AN INCH OR TWO WHICH IS REASONABLE GIVEN 2G-3G/KG MOISTURE AVBL NEAR 700MB DURING A 6 HOUR PERIOD OF STRONGER LIFT. UNCERTAINTY REMAINS WITH REGARD TO LAKE ENHANCED SNOW POTENTIAL INTO THE SE CWA. THE HIGHER RES MODELS HAVE BEEN OVERDOING PCPN WITH BANDS OFF OF LAKE MICHIGAN SO FAR. HOWEVER...AS THE DEEPER MOISTURE ARRIVES...EXPECT THAT THE LAKE CONTRIBUTION MAY ADD AN ADDITIONAL 1-2 INCHES TO SNOWFALL AMOUNTS. SINCE THE WINDS WERE BACKING MORE SERLY AHEAD OF THE LOW...THE BEST LOW LEVEL CONV AND OVER WATER TRAJECTORIES HAVE SHIFTED TO THE WEST. SO...HAVE CANCELLED THE ADVY FOR LUCE COUNTY AND CONTINUED MENTION OF 2 TO 4 INCHES OF SNOW IN THE ADVY FOR SCHOOLCRAFT COUNTY TODAY. MODELS SUGGEST THAT THE DEEPER MOISTURE WILL QUICKLY DEPART THIS AFTERNOON OVER THE WEST. HOWEVER...LACK OF LOW LEVEL LIFT OR FOCUSING MECHANISM SHOULD MINIMIZE POTENTIAL FOR -FZDZ. SOME LIGHT SNOW WILL LINGER OVER THE ERN CWA TONIGHT AS THE SFC-850 MB TROUGH SLOWLY PIVOTS TO THE NORTHEAST. FRIDAY...MODELS WERE IN AGREEMENT THAT THE PCPN ASSOCIATED WITH A SHORTWAVE MOVING FROM THE PAC THROUGH THE NRN PLAINS INTO THE MS VALLEY AND SRN GREAT LAKES IS EXPECTED TO REMAIN SOUTH OF UPPER MI. SOME ISOLATED LIGHT SNOW SHOWERS MAY BE POSSIBLE NEAR AN INVERTED TROUGH AXIS INTO THE NRN CWA. AGAIN...-FZDZ MAY ALSO BE POSSIBLE BUT PROBABILITIES REMAIN LOW. SAT INTO SUN...THE NEXT MID LEVEL TROUGH IN THE PROGRESSIVE PATTERN WILL MOVE INTO THE REGION BY LATE SAT. WAA AHEAD OF THE MID LEVEL AND SFC TROUGH MAY BRING SOME LIGHT PCPN INTO THE WRN CWA. THE MORE CONSISTENT ECMWF WAS PREFERRED FOR DETAILS WITH THE SYSTEM AS THE GFS AND NAM HAVE AT TIMES SHOWED A STRONGER SHORTWAVE SWEEPING THROUGH THE REGION THAT WOULD GENERATE SUBSTANTIAL PCPN AND BRING MUCH GREATER DEEPENING OF THE SFC LOW. FALLING TEMPS AND BLUSTERY WNW WINDS ARE EXPECTED BY SUN AFTERNOON BEHIND A STRONG COLD FRONT. SUN NIGHT INTO TUE...AS THE PATTERN BRIEFLY AMPLIFIES...MUCH COLDER AIR WILL POUR INTO THE WRN LAKES ON NW TO N WINDS DROPPING 850 MB TEMPS TO AROUND -20C. SUBTLE MODEL DIFFERENCES REMAIN WITH THE PREVAILING WIND DIRECTION AS THE GFS REMAINS MORE TO THE NW COMPARED TO THE NRLY DIRECTION DEPICTED BY THE ECMWF/GEM. SIGNIFICANT LES REMAINS POSSIBLE WITH INTENSITY DROPPING OFF MON AS DEEPER MOISTURE DEPARTS. && .AVIATION /FOR THE 18Z TAF ISSUANCE/... A LOW PRESSURE SYSTEM MOVING S OF THE AREA EARLY AFTN WILL BRING -SN AND IFR CONDITIONS TO KCMX/KSAW. LIGHT SNOW HAS ALREADY DIMINISHED AT KIWD. EVEN ONCE THE SNOW ENDS...COULD BE DIFFICULT TO GET RID OF THE LOWER CIGS GIVEN LIGHT LOW-LEVEL WINDS AND THUS WEAK ADVECTION OF ANY DRIER AIR AT THE LOW-LEVELS. EXPECT IFR CIGS TO POSSIBLY LINGER ALL NIGHT AT KCMX WITH WINDS COMING OFF OF LK SUPERIOR. EXPECT IMPROVEMENT AT KIWD/KSAW TO AT LEAST MVFR. && .MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/... A LOW PRESSURE SYSTEM OVER MN WILL MOVE EAST TODAY. ALTHOUGH WINDS SHOULD STAY BELOW GALE FORCE...THEY WILL BECOME RATHER GUSTY OUT OF THE SOUTHEAST WITH PERHAPS A GUST OR TWO CLOSE TO GALE FORCE. AFTER ANOTHER LOW MOVES ACROSS THE LOWER LAKES ON FRIDAY...A WEAK RIDGE BUILDS ACROSS LAKE SUPERIOR INTO SATURDAY BEFORE A STRONG LOW DEVELOPS OVER THE PLAINS AND MOVES NORTH OF LAKE SUPERIOR FOR NEW YEARS DAY. HIGH END NORTH-NORTHWEST GALES ARE POSSIBLE WITH THIS SYSTEM INTO MONDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ013- 014-085. WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ001. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...JLA SYNOPSIS...JLB DISCUSSION...JLB AVIATION...JLA MARINE...TITUS
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1133 AM EST THU DEC 29 2011 .UPDATE... LIGHT SNOW HAS SPREAD ACROSS THE AREA NORTH OF SFC LOW OVER SOUTHERN WI. SNOW HAS BEEN HEAVIER OVER SOUTH CENTRAL UPPER MICHIGAN AND ALSO OVER LK SUPERIOR OVR KEWEENAW PENINSULA. SO FAR...HIGHEST AMOUNTS WITH THE SYSTEM HAVE BEEN LESS THAN AN INCH. SE BLYR WINDS OFF LK MICHIGAN WILL CONTRIBUTE TO INCREASING LAKE ENHANCED SNOW FOR DELTA COUNTY AND SCHOOLCRAFT COUNTY THIS AFTN. NOT ALL THAT COLD AT H85 BUT INVERSION TOP TEMPS ARE SLIGHTLY COLDER...AROUND -8C...LEADING TO DELTA T/S AROUND 13C. SCNTRL UPR MI IS ALSO WHERE RUC INDICATES PERIOD OF H85 THETA-E ADVECTION TO ENHANCE THE SNOW. OPTED TO INCLUDE DELTA COUNTY IN SNOW ADVY FOR AFTN. TOTAL SNOW AMOUNTS WILL BE A STRETCH TO REACH 4 INCHES FOR THE AFTN...BUT TOTALS IN THE 2 TO 4 INCH RANGE WITH LOWER VSBY...DOWN TO 1/2SM IN HEAVIER SNOW...SEEMS TO JUSTIFY PUTTING DELTA INTO THE ADVY. EXPECT HEAVIER SNOW TO CEASE BY LATE AFTN OR EARLY EVENING AS BETTER THETA-E ADVECTION DIMINISHES TO THE EAST AS MAIN SHORTWAVE MOVES OUT OF THE AREA. OTHER SPOT TO WATCH WILL BE KEWEENAW AS SIMILAR SETUP IS PRESENT. SHEAR IN LOWEST 2KFT IS MORE NOTED WITH ESE WINDS AT SFC AND MORE SRLY WINDS TOWARD 925MB PER MQT VWP. HIGHER TERRAIN OF KEWEENAW COUNTY IS ORIENTED MORE WEST-TO-EAST SO WITH THE SOUTHERLY WINDS IN LOW-LEVELS THERE IS MORE OF AN UPSLOPE COMPONENT THERE COMPARED TO HOUGHTON COUNTY. COUNTY SHERIFF REPORTS A COUPLE INCHES THUS FAR OVR HIGHER TERRAIN. SINCE HEAVIER SNOW MAY LAST A FEW HOURS LONGER BASED ON STRONGER H85 THETA-E ADVECTION...WILL PUT ADVY UP FOR KEWEENAW COUNTY FOR THE AFTN. && PREV DISCUSSION...ISSUED AT 631 AM EST THU DEC 29 2011... .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A STRONG WRLY MID/UPPER LEVEL FLOW INTO THE PAC NW AND WNW FLOW DOWNSTREAM FROM THE SRN CANADA AND NRN PLAINS INTO THE GREAT LAKES. ONE SHEARED SHORTWAVE TROUGH WAS LOCATED NORTH OF LAKE SUPERIOR AND ANOTHER WAS MOVING THROUGH SW MN. AT THE SFC...A 997 MB LOW WAS LOCATED OVER SRN MN RESULTING IN S TO SE WINDS ACROSS UPPER MICHIGAN. AN AREA OF SNOW FROM NE MN INTO WRN LAKE SUPERIOR NW WI WITH VSBYS INTO THE 1-3SM RANGE WAS SUPPORTED BY 285K-290K ASCENT AHEAD OF A 850-700 MB TROUGH. ANY LAKE EFFECT/ENHANCED SNOW OFF OF LAKE MICHIGAN WITH THE SRLY FLOW HAS BEEN MINIMAL WITH ONLY A DUSTING AT MOST. && .DISCUSSION... TODAY AND TONIGHT...EXPECT THE AREA OF SNOW TO PROGRESS ACROSS UPPER MICHIGAN TODAY. MODELS CONSENSUS QPF OF AROUND A TENTH OF AN INCH WITH SNOW/WATER RATIO VALUES NEAR 15/1 WOULD RESULT IN SNOWFALL AMOUNTS OF AN INCH OR TWO WHICH IS REASONABLE GIVEN 2G-3G/KG MOISTURE AVBL NEAR 700MB DURING A 6 HOUR PERIOD OF STRONGER LIFT. UNCERTAINTY REMAINS WITH REGARD TO LAKE ENHANCED SNOW POTENTIAL INTO THE SE CWA. THE HIGHER RES MODELS HAVE BEEN OVERDOING PCPN WITH BANDS OFF OF LAKE MICHIGAN SO FAR. HOWEVER...AS THE DEEPER MOISTURE ARRIVES...EXPECT THAT THE LAKE CONTRIBUTION MAY ADD AN ADDITIONAL 1-2 INCHES TO SNOWFALL AMOUNTS. SINCE THE WINDS WERE BACKING MORE SERLY AHEAD OF THE LOW...THE BEST LOW LEVEL CONV AND OVER WATER TRAJECTORIES HAVE SHIFTED TO THE WEST. SO...HAVE CANCELLED THE ADVY FOR LUCE COUNTY AND CONTINUED MENTION OF 2 TO 4 INCHES OF SNOW IN THE ADVY FOR SCHOOLCRAFT COUNTY TODAY. MODELS SUGGEST THAT THE DEEPER MOISTURE WILL QUICKLY DEPART THIS AFTERNOON OVER THE WEST. HOWEVER...LACK OF LOW LEVEL LIFT OR FOCUSING MECHANISM SHOULD MINIMIZE POTENTIAL FOR -FZDZ. SOME LIGHT SNOW WILL LINGER OVER THE ERN CWA TONIGHT AS THE SFC-850 MB TROUGH SLOWLY PIVOTS TO THE NORTHEAST. FRIDAY...MODELS WERE IN AGREEMENT THAT THE PCPN ASSOCIATED WITH A SHORTWAVE MOVING FROM THE PAC THROUGH THE NRN PLAINS INTO THE MS VALLEY AND SRN GREAT LAKES IS EXPECTED TO REMAIN SOUTH OF UPPER MI. SOME ISOLATED LIGHT SNOW SHOWERS MAY BE POSSIBLE NEAR AN INVERTED TROUGH AXIS INTO THE NRN CWA. AGAIN...-FZDZ MAY ALSO BE POSSIBLE BUT PROBABILITIES REMAIN LOW. SAT INTO SUN...THE NEXT MID LEVEL TROUGH IN THE PROGRESSIVE PATTERN WILL MOVE INTO THE REGION BY LATE SAT. WAA AHEAD OF THE MID LEVEL AND SFC TROUGH MAY BRING SOME LIGHT PCPN INTO THE WRN CWA. THE MORE CONSISTENT ECMWF WAS PREFERRED FOR DETAILS WITH THE SYSTEM AS THE GFS AND NAM HAVE AT TIMES SHOWED A STRONGER SHORTWAVE SWEEPING THROUGH THE REGION THAT WOULD GENERATE SUBSTANTIAL PCPN AND BRING MUCH GREATER DEEPENING OF THE SFC LOW. FALLING TEMPS AND BLUSTERY WNW WINDS ARE EXPECTED BY SUN AFTERNOON BEHIND A STRONG COLD FRONT. SUN NIGHT INTO TUE...AS THE PATTERN BRIEFLY AMPLIFIES...MUCH COLDER AIR WILL POUR INTO THE WRN LAKES ON NW TO N WINDS DROPPING 850 MB TEMPS TO AROUND -20C. SUBTLE MODEL DIFFERENCES REMAIN WITH THE PREVAILING WIND DIRECTION AS THE GFS REMAINS MORE TO THE NW COMPARED TO THE NRLY DIRECTION DEPICTED BY THE ECMWF/GEM. SIGNIFICANT LES REMAINS POSSIBLE WITH INTENSITY DROPPING OFF MON AS DEEPER MOISTURE DEPARTS. && .AVIATION /FOR THE 12Z TAF ISSUANCE/... A LOW PRESSURE SYSTEM MOVING S OF THE AREA TODAY WILL BRING -SN TO ALL TAF SITES...RESULTING IN IFR CONDITIONS. LIFR CONDITIONS ARE POSSIBLE AS WELL...ESPECIALLY AT KCMX...DURING PERIOD OF HEAVIEST SNOW. IMPROVEMENT EXPECTED W TO E LATE MORNING/AFTN AS MAIN AREA OF -SN EXITS. HOWEVER...IT MAY BE DIFFICULT TO GET RID OF THE LOWER CIGS GIVEN LIGHT LOW-LEVEL WINDS AND THUS WEAK ADVECTION OF ANY DRIER AIR AT THE LOW-LEVELS. SO...CIGS MAY REMAIN IFR OR ONLY RISE SLIGHTLY TO LOW MVFR IN THE AFTN. IWD IS THE MOST LIKELY TO SEE SIGNIFICANT IMPROVEMENT. && .MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/... A LOW PRESSURE SYSTEM OVER MN WILL MOVE EAST TODAY. ALTHOUGH WINDS SHOULD STAY BELOW GALE FORCE...THEY WILL BECOME RATHER GUSTY OUT OF THE SOUTHEAST WITH PERHAPS A GUST OR TWO CLOSE TO GALE FORCE. AFTER ANOTHER LOW MOVES ACROSS THE LOWER LAKES ON FRIDAY...A WEAK RIDGE BUILDS ACROSS LAKE SUPERIOR INTO SATURDAY BEFORE A STRONG LOW DEVELOPS OVER THE PLAINS AND MOVES NORTH OF LAKE SUPERIOR FOR NEW YEARS DAY. HIGH END NORTH-NORTHWEST GALES ARE POSSIBLE WITH THIS SYSTEM INTO MONDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ013- 014-085. WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ001. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...JLA SYNOPSIS...JLB DISCUSSION...JLB AVIATION...TITUS MARINE...TITUS
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
326 PM CST THU DEC 29 2011 .UPDATE... .AVIATION... MID AND HIGH LEVEL CLOUDS WILL CONTINUE ACROSS WESTERN AND NORTH CENTRAL NEBRASKA THIS AFTERNOON...WITH SKIES CLEARING TONIGHT. CEILINGS MAY GET AS LOW AS 5000 FT AGL...ALONG WITH SCT RAIN SHOWERS AND A FEW THUNDERSTORMS LATE THIS AFTERNOON AND EARLY THIS EVENING. OVERALL VFR EXPECTED TO PREVAIL...WITH GUSTY WEST WINDS TO 40 KTS WEST OF HIGHWAY 183 FROM LATE AFTERNOON THROUGH THE EVENING. LOCAL GUSTS TO 50 KTS ARE POSSIBLE INVOF SHOWERS/STORMS. && .PREV DISCUSSION... /ISSUED 321 PM CST THU DEC 29 2011/ DISCUSSION... SHORT TERM... WIND ADVISORY CONDITIONS ARE SPREADING THROUGH ALL OF THE WRN NEB PANHANDLE THIS AFTERNOON. THERE IS THE POTENTIAL FOR STRONG WINDS TO SPREAD THROUGH ALL OF THE PANHANDLE UNTIL 23Z. THEREAFTER THE LOSS OF DAYTIME HEATING SHOULD CAUSE A DROP IN GUSTS. 30 MPH SUSTAINED CONDITIONS MIGHT CONTINUE THIS EVENING AS LOW PRESSURE TRACKS THROUGH THE MISSOURI BASIN. THE RUC SHOWS A PRONOUNCED TROP FOLD ON THE PV15 SURFACE WHICH SHOULD MOVE THRU THE FCST AREA THIS EVENING. THUS THE WIND ADZY WILL CONTINUE ACROSS GARDEN AND DEUEL COUNTIES WITH A POSSIBLE NORTH AND EAST EXPANSION AS CONDITIONS WARRANT. SCATTERED SHOWERS ISOLATED THUNDERSTORMS ARE EXPECTED TO CONTINUE TRACKING THRU NRN NEB THIS EVENING. THE STRONG WEST WINDS ARE BEING USHERED IN AHEAD OF A PACIFIC COLD FRONT WORKING THRU NERN WY. THE FRONT SHOULD COOL TEMPS OFF SOMEWHAT FOR FRIDAY WITH HIGHS ABOUT 10F COOLER THAN TODAY. ANOTHER STRONG COLD FRONT IS EXPECTED TO MOVE THROUGH SATURDAY MORNING...EARLY AFTERNOON. THIS FRONT IN COMBINATION WITH DEEPENING LOW PRESSURE ACROSS THE UPPER MIDWEST AND VERY STRONG PACIFIC HIGH PRESSURE SHOULD PRODUCE WIND ADVISORY CONDITIONS ACROSS MOST AND POSSIBLY ALL OF THE FCST AREA. A BLEND OF MODEL DATA AND GUIDANCE WAS USED FOR THE FCST WHICH PRODUCED HIGH END WIND ADVISORY CONDITIONS ACROSS SWRN NEB. AMPLE MOISTURE WILL BE PRESENT ALONG AND BEHIND THE FRONT SATURDAY FOR SCATTERED RAIN AND SNOW SHOWERS...MAINLY ACROSS THE NORTH. ANOTHER STRONG TROP FOLD WILL SWEEP THE FCST AREA IN CONCERT WITH THE FRONTAL PASSAGE. THE GFS WAS OVERPOWERING WITH THE WIND STRENGTH AND COLD AIR PRODUCING ALL SNOW WHILE THE NAM SHOWED A MIX WITH WEAKER WINDS. THE WARMER NAM WAS PREFERRED. PACIFIC HIGH PRESSURE WILL BUILD ACROSS THE FCST AREA SUNDAY PRODUCING HIGHS IN THE UPPER 30S TO AROUND 40 WITH NEARLY CLEAR SKIES. LONG TERM... A RIDGE OF HIGH PRESSURE ALOFT WILL BE AMPLIFYING MONDAY ACROSS THE ROCKIES...WHILE A TROUGH OF LOW PRESSURE CONTINUES IT/S EASTWARD PROGRESSION INTO THE NORTHEAST STATES. OUR AREA WILL BE IN BETWEEN THESE TWO FEATURES...WITH A BROAD NORTHWEST FLOW ALOFT. 850 MB TEMPERATURES WILL BEGIN TO RECOVER MONDAY...AND CONTINUE TO WARM THOUGH THURSDAY. IN FACT BY THURSDAY MODELS ARE SUGGESTING +15C OVER THE AREA...WHICH WOULD PUT HIGH TEMPERATURES INTO POSSIBLE RECORD TERRITORY. SO AFTER A COOL START MONDAY...HIGHS MID 30S TO MID 40S...TUESDAY THROUGH THURSDAY LOOKING VERY MILD. COULD BE PUSHING 60 DEGREES OR WARMER AGAIN BY THURSDAY. AVIATION... MID AND HIGH LEVEL CLOUDS WILL CONTINUE ACROSS WESTERN AND NORTH CENTRAL NEBRASKA THIS AFTERNOON...WITH SKIES CLEARING TONIGHT. CEILINGS MAY GET AS LOW AS 5000 FT AGL...ALONG WITH A FEW RAIN SHOWERS...ACROSS NORTH CENTRAL NEBRASKA LATE THIS AFTERNOON AND EARLY THIS EVENING. VFR EXPECTED TO PREVAIL...WITH GUSTY WEST WINDS TO 30 KTS WEST OF HIGHWAY 83 FROM LATE AFTERNOON THROUGH THE EVENING. && .LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY UNTIL 11 PM MST THIS EVENING FOR NEZ022-056. && $$ SHORT TERM...CDC AVIATION/EXTENDED...TAYLOR
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
321 PM CST THU DEC 29 2011 .DISCUSSION... .SHORT TERM... WIND ADVISORY CONDITIONS ARE SPREADING THROUGH ALL OF THE WRN NEB PANHANDLE THIS AFTERNOON. THERE IS THE POTENTIAL FOR STRONG WINDS TO SPREAD THROUGH ALL OF THE PANHANDLE UNTIL 23Z. THEREAFTER THE LOSS OF DAYTIME HEATING SHOULD CAUSE A DROP IN GUSTS. 30 MPH SUSTAINED CONDITIONS MIGHT CONTINUE THIS EVENING AS LOW PRESSURE TRACKS THROUGH THE MISSOURI BASIN. THE RUC SHOWS A PRONOUNCED TROP FOLD ON THE PV15 SURFACE WHICH SHOULD MOVE THRU THE FCST AREA THIS EVENING. THUS THE WIND ADZY WILL CONTINUE ACROSS GARDEN AND DEUEL COUNTIES WITH A POSSIBLE NORTH AND EAST EXPANSION AS CONDITIONS WARRANT. SCATTERED SHOWERS ISOLATED THUNDERSTORMS ARE EXPECTED TO CONTINUE TRACKING THRU NRN NEB THIS EVENING. THE STRONG WEST WINDS ARE BEING USHERED IN AHEAD OF A PACIFIC COLD FRONT WORKING THRU NERN WY. THE FRONT SHOULD COOL TEMPS OFF SOMEWHAT FOR FRIDAY WITH HIGHS ABOUT 10F COOLER THAN TODAY. ANOTHER STRONG COLD FRONT IS EXPECTED TO MOVE THROUGH SATURDAY MORNING...EARLY AFTERNOON. THIS FRONT IN COMBINATION WITH DEEPENING LOW PRESSURE ACROSS THE UPPER MIDWEST AND VERY STRONG PACIFIC HIGH PRESSURE SHOULD PRODUCE WIND ADVISORY CONDITIONS ACROSS MOST AND POSSIBLY ALL OF THE FCST AREA. A BLEND OF MODEL DATA AND GUIDANCE WAS USED FOR THE FCST WHICH PRODUCED HIGH END WIND ADVISORY CONDITIONS ACROSS SWRN NEB. AMPLE MOISTURE WILL BE PRESENT ALONG AND BEHIND THE FRONT SATURDAY FOR SCATTERED RAIN AND SNOW SHOWERS...MAINLY ACROSS THE NORTH. ANOTHER STRONG TROP FOLD WILL SWEEP THE FCST AREA IN CONCERT WITH THE FRONTAL PASSAGE. THE GFS WAS OVERPOWERING WITH THE WIND STRENGTH AND COLD AIR PRODUCING ALL SNOW WHILE THE NAM SHOWED A MIX WITH WEAKER WINDS. THE WARMER NAM WAS PREFERRED. PACIFIC HIGH PRESSURE WILL BUILD ACROSS THE FCST AREA SUNDAY PRODUCING HIGHS IN THE UPPER 30S TO AROUND 40 WITH NEARLY CLEAR SKIES. .LONG TERM... A RIDGE OF HIGH PRESSURE ALOFT WILL BE AMPLIFYING MONDAY ACROSS THE ROCKIES...WHILE A TROUGH OF LOW PRESSURE CONTINUES IT/S EASTWARD PROGRESSION INTO THE NORTHEAST STATES. OUR AREA WILL BE IN BETWEEN THESE TWO FEATURES...WITH A BROAD NORTHWEST FLOW ALOFT. 850 MB TEMPERATURES WILL BEGIN TO RECOVER MONDAY...AND CONTINUE TO WARM THOUGH THURSDAY. IN FACT BY THURSDAY MODELS ARE SUGGESTING +15C OVER THE AREA...WHICH WOULD PUT HIGH TEMPERATURES INTO POSSIBLE RECORD TERRITORY. SO AFTER A COOL START MONDAY...HIGHS MID 30S TO MID 40S...TUESDAY THROUGH THURSDAY LOOKING VERY MILD. COULD BE PUSHING 60 DEGREES OR WARMER AGAIN BY THURSDAY. && .AVIATION... MID AND HIGH LEVEL CLOUDS WILL CONTINUE ACROSS WESTERN AND NORTH CENTRAL NEBRASKA THIS AFTERNOON...WITH SKIES CLEARING TONIGHT. CEILINGS MAY GET AS LOW AS 5000 FT AGL...ALONG WITH A FEW RAIN SHOWERS...ACROSS NORTH CENTRAL NEBRASKA LATE THIS AFTERNOON AND EARLY THIS EVENING. VFR EXPECTED TO PREVAIL...WITH GUSTY WEST WINDS TO 30 KTS WEST OF HIGHWAY 83 FROM LATE AFTERNOON THROUGH THE EVENING. && .LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY UNTIL 11 PM MST THIS EVENING FOR NEZ022-056. && $$ SHORT TERM...CDC AVIATION/EXTENDED...TAYLOR