Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/25/13


AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1208 PM MST MON DEC 23 2013 .UPDATE... ISSUED AT 1208 PM MST MON DEC 23 2013 ALLOWED WINTER WEATHER ADVISORIES FOR ALL BUT THE ELKHEAD AND PARK RANGES TO EXPIRE AT NOON. AS PREVIOUSLY DISCUSSED...THE ELKHEAD AND PARK RANGES HAVE BEEN UPGRADED TO A WINTER STORM WARNING WHICH IS IN EFFECT THROUGH TUESDAY AFTERNOON. HOWEVER...ISSUED ANOTHER SET OF WINTER WEATHER ADVISORIES FOR STEAMBOAT SPRINGS AND SURROUNDING AREAS... THE FLAT TOPS...AND THE GORE RANGE AND NORTH CENTRAL MOUNTAINS BEGINNING LATE TONIGHT AND CONTINUING THROUGH TUESDAY AFTERNOON. A MORE DETAILED DISCUSSION FORTHCOMING WITH THE AFTERNOON ISSUANCE. UPDATE ISSUED AT 904 AM MST MON DEC 23 2013 SNOTEL DATA INDICATED SIGNIFICANT SNOWFALL OCCURRED OVER THE PAST 24 HOURS IN THE ELKHEAD AND GORE MOUNTAINS (ZONE 4). ACCUMULATIONS RANGED FROM ROUGHLY 10 TO 18 INCHES ON AVERAGE WITH SOME HIGHER AMOUNTS. SURROUNDING MOUNTAIN AREAS ABOVE 7500 FEET RECEIVED CONSIDERABLY LESS SNOWFALL DURING THIS EVENT. LATEST RUC13 AND NAM12 DATA SUGGESTED THAT SNOWFALL WILL CONTINUE OVER THE HIGHER PEAKS OF THE ELKHEAD AND PARK MOUNTAINS THROUGH THE AFTERNOON BEFORE INCREASING WITH THE NEXT SYSTEM WHICH WILL IMPACT THE AREA TONIGHT AND TUESDAY AS DESCRIBED BELOW. GIVEN SIGNIFICANT AMOUNTS ALREADY RECEIVED AND THE LACK OF ANY SUBSTANTIVE BREAK BETWEEN THESE SYSTEMS OPTED TO UPGRADE THE ADVISORY FOR ZONE 4 TO A WINTER STORM WARNING. THIS WARNING WILL CONTINUE THROUGH 6 PM MST TUESDAY. MEANWHILE...THERE WILL BE AN END IN SNOWFALL FOR THE OTHER ZONES IN THE THE ADVISORIES ALREADY IN PLACE AND PLAN TO LET THOSE EXPIRE AT NOON. MEANWHILE...FOG NOT AS PREVALENT THIS MORNING SO WILL BE REMOVING IT FROM TODAY/S FORECAST. && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 414 AM MST MON DEC 23 2013 MODERATELY FAST NORTHWEST FLOW REMAINS IN PLACE OVER THE CENTRAL AND NORTHERN ROCKIES...SQUEEZED BETWEEN A MID CONUS TROF AND RIDGING ALONG THE LEFT COAST. WATER VAPOR IMAGERY AND REGIONAL PROFILER NETWORK SHOWING THE BACK EDGE OF ONE WAVE EXITING THE HIGH PLAINS WITH A MORE DEFINED KICKER SYSTEM JUST MOVING ONTO THE BRITISH COLUMBIA COASTLINE. DERIVED SATELLITE IMAGERY SHOWING ANOTHER DECENT PUSH OF MOISTURE INTO THE PACIFIC NORTHWEST COMING IN WITH THIS JET MAX WITH PWAT RUNNING SOME 150 PERCENT OF NORMAL JUST UPSTREAM OF SLC TO THE WASHINGTON COAST. WEB CAMS AND SURFACE OBS SHOW SNOW CONTINUING ALONG THE PARK AND GORE RANGES DOWN TO STEAMBOAT SPRING AND VAIL AREAS EARLY THIS MORNING. WILL BE KEEPING THE WINTER WEATHER ADVISORY GOING TO NOON AS CURRENTLY ADVERTISED. WE SHOULD SEE A DECREASING TREND IN COVERAGE OF THE PRECIPITATION THIS MORNING AS LAPSE RATES RELAX WITH A TRANSITORY RIDGE SLIPPING OVERHEAD. MOIST OROGRAPHICS WILL LIKELY KEEP LIGHT GOING OVER THE DIVIDE NORTH OF VAIL PASS THROUGH THE DAY BUT ADDITIONAL AMOUNTS LOOK MINIMAL. CLOUD COVER AND ENOUGH MIXING SEEMS TO HAVE THE PBL STIRRED UP ENOUGH TO PREVENT THE FOG OF PREVIOUS NIGHTS SO FAR. HAVE KEPT THE MENTION...BUT REDUCED TO PATCHY AS NOT CONVINCED IT WON/T TRY TO REFORM BY SUNRISE...ESPECIALLY THE UINTA VALLEY. TEMPERATURES MAY WARM A FEW DEGREES IN AREAS NORTH OF I-70 BUT FOR THE MOST PART HAVE KEPT FORECAST BELOW GUIDANCE FOR HIGHS TODAY. THETA SURFACES AT 300-310K SHOW A CONSTANT FEED OF MOISTURE TODAY...FEEDING THE LIGHT OROGRAPHIC SHOWERS IN THE NORTHWEST MOUNTAINS. LARGE SCALE ASCENT WILL BE INCREASING OVER OUR NORTHERN CWA LATE THIS EVENING AS THE MAIN SYSTEM MOVES ACROSS NORTHERN WYOMING AND MONTANA. THIS ASCENT WILL HELP FOCUS THE MOISTURE AND TOP DOWN SATURATION WILL BE INCREASING THE SNOW THROUGH THE EARLY MORNING HOURS NORTH OF INTERSTATE 70 WHERE UPGLIDE WITH BE THE STRONGEST AND CONDENSATION DEFICITS THE LOWEST. BUFKIT PROFILES INDICATE THE FAVORED TIME FOR PRECIPITATION IN THE NORTHERN VALLEYS NEAR 12Z TUESDAY. THE UPGLIDE DECREASES QUICKLY THROUGH THE AFTERNOON AS THE WAVE PASSES TO OUR NORTHEAST. THIS SHOULD LEAD TO A NOTICEABLE DECREASE IN PRECIPITATION THROUGH THE DAY AS SNOW FOCUSES MORE ON THE HIGHER NORTHWEST FACING SLOPES AS OROGRAPHICS DOMINATE THE LIFT. THE FAST MOVEMENT AND LIMITED INSTABILITY WITH THIS WAVE POINTS TOWARD SUB ADVISORY SNOWFALL ATTM WITH THE HIGHEST AMOUNTS PINNED TO THE NORTHWEST DIVIDE. TEMPERATURES WILL STAY UP A TAD OVERNIGHT AND CLOUDS SHOULD LIMIT DENSE FOG. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 414 AM MST MON DEC 23 2013 LATEST MODEL RUNS SHOW ECMWF AND GFS IN GOOD AGREEMENT FOR ENTIRE LONG TERM FORECAST PERIOD. TUESDAY NIGHT INTO WEDNESDAY MORNING WILL SEE LIGHT SNOW FINALLY ENDING FOR NORTHERN REGIONS WITH NAM12/GFS/EC ALL IN AGREEMENT WITH THIS SCENARIO. AFTER THAT...A LARGE RIDGE OF HIGH PRESSURE WILL BUILD IN WITH AXIS JUST OFF THE WEST COAST. THIS WILL KEEP NWRLY FLOW IN THE FORECAST UNTIL FRIDAY WHEN AN AREA OF LOW PRESSURE APPROACHES NRN CALIFORNIA CAUSING RIDGE TO SHIFT EAST AND START BREAKING DOWN. BY NOON FRIDAY...ZONAL FLOW SETS UP AS A TROUGH MOVES OVER THE NRN ROCKIES AND PLAINS WHILE THE CLOSED LOW CONTINUES TO APPROACH CALIFORNIA COAST. PRESENTLY...MODELS KEEP PRECIP ASSOD WITH TROUGH WELL TO OUR N UNTIL SUNDAY AFTN WHEN NRN MTNS MAY SEE SOME LIGHT SNOWSHOWERS. AS FAR AS THE LOW PRESSURE TO THE WEST...BOTH GFS AND EC SHOW REX BLOCK SETTING UP SUNDAY ONWARDS. EVEN THOUGH THE LOW REMAINS ANCHORED OFF THE CALIFORNIA COAST...MOISTURE WILL CAUSE SOME CLOUDS OVER THE DESERT SW WILL VERY LITTLE PRECIP EXPECTED ATTM. THIS MAY CHANGE AS WE MOVE AHEAD IN TIME HOWEVER. ALL IN ALL...THE NEXT 5 DAYS WILL BE RATHER QUIET WITH SOME CLOUDS MOVING OVERHEAD FROM TIME TO TIME WITH LITTLE CHANGE FROM DAY TO DAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1001 AM MST MON DEC 23 2013 SNOW WILL CONTINUE OVER THE NORTHERN COLORADO MOUNTAINS THROUGH THE NEXT 24 HOURS RESULTING IN WIDESPREAD OBSCURATION. MVFR CIGS AND VSBY SHOULD LIFT TO VFR AT KSBS EARLY THIS AFTERNOON...BUT WILL FALL AGAIN TONIGHT AS SNOW INCREASES AHEAD OF ANOTHER SYSTEM DROPPING DOWN FROM THE NORTHWEST. AS THIS SYSTEM SETS IN KCAG... KEEO...KEGE...AND KASE WILL BE IMPACTED WITH MVFR AND POSSIBLY IFR CONDITIONS AFTER 06Z AND 18Z TUES. ELSEWHERE...THE LOWER VALLEYS MAY SEE MVFR CIGS/VSBY IN FOG TONIGHT AND TUESDAY MORNING WITH BEST CHANCES AT KVEL AND KCNY. VFR CONDITIONS WILL PREVAIL OUTSIDE OF THE AREAS MENTIONED ABOVE THROUGH THE NEXT 24 HOURS. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER STORM WARNING UNTIL 6 PM MST TUESDAY COZ004. WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM MST TUESDAY COZ005. WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM MST TUESDAY ABOVE 8000 FEET FOR COZ010. WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM MST TUESDAY COZ013. UT...NONE. && $$ UPDATE...NL SHORT TERM...15 LONG TERM...TGR AVIATION...NL
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1001 AM MST MON DEC 23 2013 .UPDATE... ISSUED AT 904 AM MST MON DEC 23 2013 SNOTEL DATA INDICATED SIGNIFICANT SNOWFALL OCCURRED OVER THE PAST 24 HOURS IN THE ELKHEAD AND GORE MOUNTAINS (ZONE 4). ACCUMULATIONS RANGED FROM ROUGHLY 10 TO 18 INCHES ON AVERAGE WITH SOME HIGHER AMOUNTS. SURROUNDING MOUNTAIN AREAS ABOVE 7500 FEET RECEIVED CONSIDERABLY LESS SNOWFALL DURING THIS EVENT. LATEST RUC13 AND NAM12 DATA SUGGESTED THAT SNOWFALL WILL CONTINUE OVER THE HIGHER PEAKS OF THE ELKHEAD AND PARK MOUNTAINS THROUGH THE AFTERNOON BEFORE INCREASING WITH THE NEXT SYSTEM WHICH WILL IMPACT THE AREA TONIGHT AND TUESDAY AS DESCRIBED BELOW. GIVEN SIGNIFICANT AMOUNTS ALREADY RECEIVED AND THE LACK OF ANY SUBSTANTIVE BREAK BETWEEN THESE SYSTEMS OPTED TO UPGRADE THE ADVISORY FOR ZONE 4 TO A WINTER STORM WARNING. THIS WARNING WILL CONTINUE THROUGH 6 PM MST TUESDAY. MEANWHILE...THERE WILL BE AN END IN SNOWFALL FOR THE OTHER ZONES IN THE THE ADVISORIES ALREADY IN PLACE AND PLAN TO LET THOSE EXPIRE AT NOON. MEANWHILE...FOG NOT AS PREVALENT THIS MORNING SO WILL BE REMOVING IT FROM TODAY/S FORECAST. && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 414 AM MST MON DEC 23 2013 MODERATELY FAST NORTHWEST FLOW REMAINS IN PLACE OVER THE CENTRAL AND NORTHERN ROCKIES...SQUEEZED BETWEEN A MID CONUS TROF AND RIDGING ALONG THE LEFT COAST. WATER VAPOR IMAGERY AND REGIONAL PROFILER NETWORK SHOWING THE BACK EDGE OF ONE WAVE EXITING THE HIGH PLAINS WITH A MORE DEFINED KICKER SYSTEM JUST MOVING ONTO THE BRITISH COLUMBIA COASTLINE. DERIVED SATELLITE IMAGERY SHOWING ANOTHER DECENT PUSH OF MOISTURE INTO THE PACIFIC NORTHWEST COMING IN WITH THIS JET MAX WITH PWAT RUNNING SOME 150 PERCENT OF NORMAL JUST UPSTREAM OF SLC TO THE WASHINGTON COAST. WEB CAMS AND SURFACE OBS SHOW SNOW CONTINUING ALONG THE PARK AND GORE RANGES DOWN TO STEAMBOAT SPRING AND VAIL AREAS EARLY THIS MORNING. WILL BE KEEPING THE WINTER WEATHER ADVISORY GOING TO NOON AS CURRENTLY ADVERTISED. WE SHOULD SEE A DECREASING TREND IN COVERAGE OF THE PRECIPITATION THIS MORNING AS LAPSE RATES RELAX WITH A TRANSITORY RIDGE SLIPPING OVERHEAD. MOIST OROGRAPHICS WILL LIKELY KEEP LIGHT GOING OVER THE DIVIDE NORTH OF VAIL PASS THROUGH THE DAY BUT ADDITIONAL AMOUNTS LOOK MINIMAL. CLOUD COVER AND ENOUGH MIXING SEEMS TO HAVE THE PBL STIRRED UP ENOUGH TO PREVENT THE FOG OF PREVIOUS NIGHTS SO FAR. HAVE KEPT THE MENTION...BUT REDUCED TO PATCHY AS NOT CONVINCED IT WON/T TRY TO REFORM BY SUNRISE...ESPECIALLY THE UINTA VALLEY. TEMPERATURES MAY WARM A FEW DEGREES IN AREAS NORTH OF I-70 BUT FOR THE MOST PART HAVE KEPT FORECAST BELOW GUIDANCE FOR HIGHS TODAY. THETA SURFACES AT 300-310K SHOW A CONSTANT FEED OF MOISTURE TODAY...FEEDING THE LIGHT OROGRAPHIC SHOWERS IN THE NORTHWEST MOUNTAINS. LARGE SCALE ASCENT WILL BE INCREASING OVER OUR NORTHERN CWA LATE THIS EVENING AS THE MAIN SYSTEM MOVES ACROSS NORTHERN WYOMING AND MONTANA. THIS ASCENT WILL HELP FOCUS THE MOISTURE AND TOP DOWN SATURATION WILL BE INCREASING THE SNOW THROUGH THE EARLY MORNING HOURS NORTH OF INTERSTATE 70 WHERE UPGLIDE WITH BE THE STRONGEST AND CONDENSATION DEFICITS THE LOWEST. BUFKIT PROFILES INDICATE THE FAVORED TIME FOR PRECIPITATION IN THE NORTHERN VALLEYS NEAR 12Z TUESDAY. THE UPGLIDE DECREASES QUICKLY THROUGH THE AFTERNOON AS THE WAVE PASSES TO OUR NORTHEAST. THIS SHOULD LEAD TO A NOTICEABLE DECREASE IN PRECIPITATION THROUGH THE DAY AS SNOW FOCUSES MORE ON THE HIGHER NORTHWEST FACING SLOPES AS OROGRAPHICS DOMINATE THE LIFT. THE FAST MOVEMENT AND LIMITED INSTABILITY WITH THIS WAVE POINTS TOWARD SUB ADVISORY SNOWFALL ATTM WITH THE HIGHEST AMOUNTS PINNED TO THE NORTHWEST DIVIDE. TEMPERATURES WILL STAY UP A TAD OVERNIGHT AND CLOUDS SHOULD LIMIT DENSE FOG. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 414 AM MST MON DEC 23 2013 LATEST MODEL RUNS SHOW ECMWF AND GFS IN GOOD AGREEMENT FOR ENTIRE LONG TERM FORECAST PERIOD. TUESDAY NIGHT INTO WEDNESDAY MORNING WILL SEE LIGHT SNOW FINALLY ENDING FOR NORTHERN REGIONS WITH NAM12/GFS/EC ALL IN AGREEMENT WITH THIS SCENARIO. AFTER THAT...A LARGE RIDGE OF HIGH PRESSURE WILL BUILD IN WITH AXIS JUST OFF THE WEST COAST. THIS WILL KEEP NWRLY FLOW IN THE FORECAST UNTIL FRIDAY WHEN AN AREA OF LOW PRESSURE APPROACHES NRN CALIFORNIA CAUSING RIDGE TO SHIFT EAST AND START BREAKING DOWN. BY NOON FRIDAY...ZONAL FLOW SETS UP AS A TROUGH MOVES OVER THE NRN ROCKIES AND PLAINS WHILE THE CLOSED LOW CONTINUES TO APPROACH CALIFORNIA COAST. PRESENTLY...MODELS KEEP PRECIP ASSOD WITH TROUGH WELL TO OUR N UNTIL SUNDAY AFTN WHEN NRN MTNS MAY SEE SOME LIGHT SNOWSHOWERS. AS FAR AS THE LOW PRESSURE TO THE WEST...BOTH GFS AND EC SHOW REX BLOCK SETTING UP SUNDAY ONWARDS. EVEN THOUGH THE LOW REMAINS ANCHORED OFF THE CALIFORNIA COAST...MOISTURE WILL CAUSE SOME CLOUDS OVER THE DESERT SW WILL VERY LITTLE PRECIP EXPECTED ATTM. THIS MAY CHANGE AS WE MOVE AHEAD IN TIME HOWEVER. ALL IN ALL...THE NEXT 5 DAYS WILL BE RATHER QUIET WITH SOME CLOUDS MOVING OVERHEAD FROM TIME TO TIME WITH LITTLE CHANGE FROM DAY TO DAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1001 AM MST MON DEC 23 2013 SNOW WILL CONTINUE OVER THE NORTHERN COLORADO MOUNTAINS THROUGH THE NEXT 24 HOURS RESULTING IN WIDESPREAD OBSCURATION. MVFR CIGS AND VSBY SHOULD LIFT TO VFR AT KSBS EARLY THIS AFTERNOON...BUT WILL FALL AGAIN TONIGHT AS SNOW INCREASES AHEAD OF ANOTHER SYSTEM DROPPING DOWN FROM THE NORTHWEST. AS THIS SYSTEM SETS IN KCAG... KEEO...KEGE...AND KASE WILL BE IMPACTED WITH MVFR AND POSSIBLY IFR CONDITIONS AFTER 06Z AND 18Z TUES. ELSEWHERE...THE LOWER VALLEYS MAY SEE MVFR CIGS/VSBY IN FOG TONIGHT AND TUESDAY MORNING WITH BEST CHANCES AT KVEL AND KCNY. VFR CONDITIONS WILL PREVAIL OUTSIDE OF THE AREAS MENTIONED ABOVE THROUGH THE NEXT 24 HOURS. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL NOON MST TODAY ABOVE 7500 FEET FOR COZ008-010-013. WINTER STORM WARNING UNTIL 6 PM MST TUESDAY ABOVE 7500 FEET FOR COZ004. WINTER WEATHER ADVISORY UNTIL NOON MST TODAY COZ005. UT...NONE. && $$ UPDATE...NL SHORT TERM...15 LONG TERM...TGR AVIATION...NL
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
904 AM MST MON DEC 23 2013 .UPDATE... ISSUED AT 904 AM MST MON DEC 23 2013 SNOTEL DATA INDICATED SIGNIFICANT SNOWFALL OCCURRED OVER THE PAST 24 HOURS IN THE ELKHEAD AND GORE MOUNTAINS (ZONE 4). ACCUMULATIONS RANGED FROM ROUGHLY 10 TO 18 INCHES ON AVERAGE WITH SOME HIGHER AMOUNTS. SURROUNDING MOUNTAIN AREAS ABOVE 7500 FEET RECEIVED CONSIDERABLY LESS SNOWFALL DURING THIS EVENT. LATEST RUC13 AND NAM12 DATA SUGGESTED THAT SNOWFALL WILL CONTINUE OVER THE HIGHER PEAKS OF THE ELKHEAD AND PARK MOUNTAINS THROUGH THE AFTERNOON BEFORE INCREASING WITH THE NEXT SYSTEM WHICH WILL IMPACT THE AREA TONIGHT AND TUESDAY AS DESCRIBED BELOW. GIVEN SIGNIFICANT AMOUNTS ALREADY RECEIVED AND THE LACK OF ANY SUBSTANTIVE BREAK BETWEEN THESE SYSTEMS OPTED TO UPGRADE THE ADVISORY FOR ZONE 4 TO A WINTER STORM WARNING. THIS WARNING WILL CONTINUE THROUGH 6 PM MST TUESDAY. MEANWHILE...THERE WILL BE AN END IN SNOWFALL FOR THE OTHER ZONES IN THE THE ADVISORIES ALREADY IN PLACE AND PLAN TO LET THOSE EXPIRE AT NOON. MEANWHILE...FOG NOT AS PREVALENT THIS MORNING SO WILL BE REMOVING IT FROM TODAY/S FORECAST. && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 414 AM MST MON DEC 23 2013 MODERATELY FAST NORTHWEST FLOW REMAINS IN PLACE OVER THE CENTRAL AND NORTHERN ROCKIES...SQUEEZED BETWEEN A MID CONUS TROF AND RIDGING ALONG THE LEFT COAST. WATER VAPOR IMAGERY AND REGIONAL PROFILER NETWORK SHOWING THE BACK EDGE OF ONE WAVE EXITING THE HIGH PLAINS WITH A MORE DEFINED KICKER SYSTEM JUST MOVING ONTO THE BRITISH COLUMBIA COASTLINE. DERIVED SATELLITE IMAGERY SHOWING ANOTHER DECENT PUSH OF MOISTURE INTO THE PACIFIC NORTHWEST COMING IN WITH THIS JET MAX WITH PWAT RUNNING SOME 150 PERCENT OF NORMAL JUST UPSTREAM OF SLC TO THE WASHINGTON COAST. WEB CAMS AND SURFACE OBS SHOW SNOW CONTINUING ALONG THE PARK AND GORE RANGES DOWN TO STEAMBOAT SPRING AND VAIL AREAS EARLY THIS MORNING. WILL BE KEEPING THE WINTER WEATHER ADVISORY GOING TO NOON AS CURRENTLY ADVERTISED. WE SHOULD SEE A DECREASING TREND IN COVERAGE OF THE PRECIPITATION THIS MORNING AS LAPSE RATES RELAX WITH A TRANSITORY RIDGE SLIPPING OVERHEAD. MOIST OROGRAPHICS WILL LIKELY KEEP LIGHT GOING OVER THE DIVIDE NORTH OF VAIL PASS THROUGH THE DAY BUT ADDITIONAL AMOUNTS LOOK MINIMAL. CLOUD COVER AND ENOUGH MIXING SEEMS TO HAVE THE PBL STIRRED UP ENOUGH TO PREVENT THE FOG OF PREVIOUS NIGHTS SO FAR. HAVE KEPT THE MENTION...BUT REDUCED TO PATCHY AS NOT CONVINCED IT WON/T TRY TO REFORM BY SUNRISE...ESPECIALLY THE UINTA VALLEY. TEMPERATURES MAY WARM A FEW DEGREES IN AREAS NORTH OF I-70 BUT FOR THE MOST PART HAVE KEPT FORECAST BELOW GUIDANCE FOR HIGHS TODAY. THETA SURFACES AT 300-310K SHOW A CONSTANT FEED OF MOISTURE TODAY...FEEDING THE LIGHT OROGRAPHIC SHOWERS IN THE NORTHWEST MOUNTAINS. LARGE SCALE ASCENT WILL BE INCREASING OVER OUR NORTHERN CWA LATE THIS EVENING AS THE MAIN SYSTEM MOVES ACROSS NORTHERN WYOMING AND MONTANA. THIS ASCENT WILL HELP FOCUS THE MOISTURE AND TOP DOWN SATURATION WILL BE INCREASING THE SNOW THROUGH THE EARLY MORNING HOURS NORTH OF INTERSTATE 70 WHERE UPGLIDE WITH BE THE STRONGEST AND CONDENSATION DEFICITS THE LOWEST. BUFKIT PROFILES INDICATE THE FAVORED TIME FOR PRECIPITATION IN THE NORTHERN VALLEYS NEAR 12Z TUESDAY. THE UPGLIDE DECREASES QUICKLY THROUGH THE AFTERNOON AS THE WAVE PASSES TO OUR NORTHEAST. THIS SHOULD LEAD TO A NOTICEABLE DECREASE IN PRECIPITATION THROUGH THE DAY AS SNOW FOCUSES MORE ON THE HIGHER NORTHWEST FACING SLOPES AS OROGRAPHICS DOMINATE THE LIFT. THE FAST MOVEMENT AND LIMITED INSTABILITY WITH THIS WAVE POINTS TOWARD SUB ADVISORY SNOWFALL ATTM WITH THE HIGHEST AMOUNTS PINNED TO THE NORTHWEST DIVIDE. TEMPERATURES WILL STAY UP A TAD OVERNIGHT AND CLOUDS SHOULD LIMIT DENSE FOG. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 414 AM MST MON DEC 23 2013 LATEST MODEL RUNS SHOW ECMWF AND GFS IN GOOD AGREEMENT FOR ENTIRE LONG TERM FORECAST PERIOD. TUESDAY NIGHT INTO WEDNESDAY MORNING WILL SEE LIGHT SNOW FINALLY ENDING FOR NORTHERN REGIONS WITH NAM12/GFS/EC ALL IN AGREEMENT WITH THIS SCENARIO. AFTER THAT...A LARGE RIDGE OF HIGH PRESSURE WILL BUILD IN WITH AXIS JUST OFF THE WEST COAST. THIS WILL KEEP NWRLY FLOW IN THE FORECAST UNTIL FRIDAY WHEN AN AREA OF LOW PRESSURE APPROACHES NRN CALIFORNIA CAUSING RIDGE TO SHIFT EAST AND START BREAKING DOWN. BY NOON FRIDAY...ZONAL FLOW SETS UP AS A TROUGH MOVES OVER THE NRN ROCKIES AND PLAINS WHILE THE CLOSED LOW CONTINUES TO APPROACH CALIFORNIA COAST. PRESENTLY...MODELS KEEP PRECIP ASSOD WITH TROUGH WELL TO OUR N UNTIL SUNDAY AFTN WHEN NRN MTNS MAY SEE SOME LIGHT SNOWSHOWERS. AS FAR AS THE LOW PRESSURE TO THE WEST...BOTH GFS AND EC SHOW REX BLOCK SETTING UP SUNDAY ONWARDS. EVEN THOUGH THE LOW REMAINS ANCHORED OFF THE CALIFORNIA COAST...MOISTURE WILL CAUSE SOME CLOUDS OVER THE DESERT SW WILL VERY LITTLE PRECIP EXPECTED ATTM. THIS MAY CHANGE AS WE MOVE AHEAD IN TIME HOWEVER. ALL IN ALL...THE NEXT 5 DAYS WILL BE RATHER QUIET WITH SOME CLOUDS MOVING OVERHEAD FROM TIME TO TIME WITH LITTLE CHANGE FROM DAY TO DAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 414 AM MST MON DEC 23 2013 SNOWFALL CONTINUES FOR THE NORTHERN COLORADO MOUNTAINS BUT SHOULD LIGHTEN UP AFTER 18Z. OCCNL IFR AND LOWER VIS AND CIGS WILL CONTINUE THROUGH THAT TIME FOR KSBS AND KHDN. MTN OBSCURATIONS WILL ALSO CONTINUE. FOG MUCH LESS WIDESPREAD THAN 24 HOURS AGO INCLUDING WITH VFR CONDITIONS AT KVEL AND KGJT. KCNY IS BEGINNING TO SEE VSBYS LOW TO IFR/MVFR AS FOG ROLLS IN AND OUT AND THIS TREND LIKELY TO CONTINUE THROUGH THE MORNING. SUNRISE SURPRISE STILL A POSSIBILITY FOR KVEL...KGJT AND KEGE BUT WILL HOLD OFF ANY MENTION FOR NOW AND KEEP VCFG IN TAFS. IF FOG DOES FORM...EXPECT IT WILL NOT DROP VIS TOO LOW...3 TO 4SM...BEFORE BURNING OFF AFTER 17Z OR SO. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL NOON MST TODAY ABOVE 7500 FEET FOR COZ008-010-013. WINTER STORM WARNING UNTIL 6 PM MST TUESDAY ABOVE 7500 FEET FOR COZ004. WINTER WEATHER ADVISORY UNTIL NOON MST TODAY COZ005. UT...NONE. && $$ UPDATE...NL SHORT TERM...15 LONG TERM...TGR AVIATION...TGR
AREA FORECAST DISCUSSION
NWS PUEBLO CO
902 AM MST MON DEC 23 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 245 AM MST MON DEC 23 2013 CURRENTLY... ANOTHER SURGE OF COOLER AIR WAS MOVING ACROSS THE PLAINS AT 2AM. LOW CLOUDS EXTENDED FROM NE EL PASO COUNTY EASTWARD TO KIOWA COUNTY. OVER THE C MTN REGION LIGHT SNOW WAS NOTED. OTHERWISE...IT WAS MOSTLY CLEAR OVER THE REGION. TODAY.. IN THE SHORT TERM...EARLY THIS MORNING...HRRR SHOWS CLOUDS INCREASING OVER THE PLAINS AND THE NDFD WAS DRAWN UP TO ACCOUNT FOR THESE INCREASING CLOUDS. HOWEVER...BY MID MORNING...CLOUDS SHOULD DECREASE RAPIDLY OVER MOST OF THE PLAINS AS WESTERLY SFC FLOW DEVELOPS AS A LEE TROUGH SETS UP OVER THE PLAINS. THIS TROUGH WILL SET UP N-S IN THE VICINITY OF KLAA. TO THE EAST OF THE TROUGH COOLER SOUTHERLY FLOW WILL OCCUR AND TEMPS WILL NOT BE AS HIGH AS TEMPS TO THE WEST OF THE SFC TROUGH AXIS. EXPECT HIGHS ON THE PLAINS WEST OF THE LEE TROUGH TO BE IN THE 40S...WHILE 30S WILL OCCUR EAST OF IT. THE SAN LUIS VALLEY WILL REMAIN TRAPPED IN THE INVERSION AND EXPECT MAINLY L20S IN THE VALLEY. WE MAY SEE SOME GROUND FOG IN THE VALLEY EARLY THIS MORNING. LIGHT SNOW SHOWERS WILL CONTINUE OVER THE C MTNS TODAY. TONIGHT... ANOTHER DISTURBANCE IN THE NW FLOW WILL RAPIDLY MOVE TOWARDS THE REGION TOWARDS SUNRISE TUESDAY. THE MAIN AFFECTS OF THIS SYSTEM WILL BE INCREASING SNOW FOR THE C MTNS ONCE AGAIN. ALSO WESTERLY SFC FLOW OVER THE E SLOPES OF THE MTNS WILL ALLOW FOR RELATIVELY WARMER MIN TEMPS TO OCCUR IN THE TYPICAL BANANA BELT REGIONS. GUSTY WINDS WILL OCCUR IN THE MTNS...ESPECIALLY THE C MTNS...SANGRES...WETS AND PIKE PEAK. WE MAY SEE SOME LOCALLY GUSTY WINDS ON THE RAMPARTS TOWARDS SUNRISE. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 245 AM MST MON DEC 23 2013 ...DRY WEATHER FOR THE REST OF 2013.... UNEVENTFUL WEATHER PATTERN SHOWS NO SIGN OF LETTING UP...AS A PERSISTENT BLOCK OVER THE ERN PACIFIC AND WRN SATES KEEPS DISTURBANCES FROM MOVING INTO THE ROCKIES. TUESDAY...THE SRN END OF A SHORT WAVE MOVING THROUGH THE NRN PLAINS WILL BRUSH THROUGH CO DURING THE AFTERNOON. THE ECMWF AND GFS CONTINUE TO INDICATE SOME VERY LIGHT QPF OVER THE PALMER DVD AND PORTIONS OF THE PLAINS...BUT LOOKING AT THE SOUNDINGS IT LOOKS LIKE THIS PRECIP IS GENERATED FROM A RELATIVELY SHALLOW SATURATED LAYER FROM AROUND H5-H6. UPPER LEVELS AND LOWEST LEVELS LOOK PRETTY DRY. THE NAM DOES NOT EVEN HAVE THE MOIST LAYER AND KEEPS OUR AREA COMPLETELY DRY EXCEPT FOR THE EXPECTED LIGHT SHSN OVER LAKE COUNTY. SUSPECT THERE WILL BE SOME LIGHT FLURRIES OR SHOWERS AT BEST...SO WILL KEEP POPS SILENT OVER THE PLAINS. MAIN IMPACT FROM THE DISTURBANCE WILL BE SOME BREEZY CONDITIONS OVER THE MTS DURING THE MORNING AND AFTERNOON...AND SOME GUSTY N WINDS OVER THE PLAINS IN THE AFTERNOON. LIGHT W-NW FLOW CONTINUES ON WED...AND WOULD NOT BE SURPRISED TO SEE TEMPS COME IN A BIT HIGHER THAN CURRENTLY FORECAST...BUT IT WILL BE COOLER ON CHRISTMAS. THE UPPER RIDGE BUILDS STRONGLY ON THU AND FRIDAY...AND WE ARE BACK TO ABOVE AVERAGE TEMPS AND CONTINUED VERY DRY CONDITIONS. TEMPS COULD RISE INTO THE 60S ON FRIDAY BEFORE THE NEXT SYSTEM MOVES IN FROM THE NW NEXT WEEKEND. THIS FRONT LOOKS SIMILAR TO WHAT WE HAVE BEEN SEEING...NOT MUCH CHANCE FOR ANY SIGNIFICANT PRECIP. AT SOME POINT A CUTOFF LOW OVER THE CA COAST WILL EJECT EWD INTO OUR AREA...BUT WITHOUT ANY STRONG PACIFIC JET SUPPORT IT LOOKS LIKE MORE OF THE SAME FOR US...DRY AND MILD. HOPEFULLY THE PATTERN WILL BECOME MORE ACTIVE IN JANUARY OR ALL THE GAINS WE MADE EARLY THIS SEASON IN THE MT SNOWPACK WILL BE LOST. ROSE && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 857 AM MST MON DEC 23 2013 EASTERLY UPSLOPE FLOW HAS BROUGHT STRATUS WITH MVFR CIGS TO PORTIONS OF THE SOUTHEAST PLAINS. THESE HAVE SPREAD INTO BOTH THE KCOS AND KPUB TERMINALS WITH LIFR CIGS AT KCOS WHERE UPSLOPE HAS CAUSED FOG AND EVEN FLURRIES TO FORM ON THE SOUTHERN SLOPES OF THE PALMER DIVIDE. RAP MODEL SEEMS TO HAVE CAUGHT ON TO THIS FAIRLY WELL AND HAS CIGS DISSIPATING FOR KCOS AND KPUB BY 18Z. HAVE INTRODUCED SOME CIGS INTO KPUB...AND WILL MONITOR THE END TIME OF 17Z AT KCOS AS THIS MAY NEED TO BE EXTENDED ANOTHER HOUR BASED ON LATEST SATELLITE TRENDS. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...HODANISH LONG TERM...ROSE AVIATION...KT
AREA FORECAST DISCUSSION
NWS ALBANY NY
403 AM EST MON DEC 23 2013 .SYNOPSIS... LOW PRESSURE WILL MOVE UP THE EASTERN SEABOARD TODAY...BRINGING ONE MORE ROUND OF RAIN TO SOUTHERN NEW ENGLAND AND IN NEW YORK FROM THE CAPITAL DISTRICT SOUTH. IN ITS WAKE COLD AIR WILL FILTER INTO OUR REGION THIS AFTERNOON AS WINDS INCREASE. EVEN COLDER AIR WILL MOVE INTO THE REGION AS HIGH PRESSURE MOVES FROM ONTARIO TONIGHT TO NEW YORK AND NEW ENGLAND CHRISTMAS DAY. THE REST OF THE WEEK WILL FEATURE A SERIES OF WEAK FAST MOVING WEATHER SYSTEMS...WITH VARIABLE CLOUDINESS...SCATTERED SNOW SHOWERS AND SEASONABLE TEMPERATURES. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 300 AM EST...NEARLY STATIONARY FRONTAL BOUNDARY CONTINUES TO BE SITUATED FROM WEST TO EAST ACROSS THE CENTRAL PORTION OF THE CWA EARLY THIS MORNING. TO THE NORTH OF THIS BOUNDARY...IMPRESSIVE CAD CONTINUES ACROSS THE LAKE GEORGE/SARATOGA REGION...WITH TEMPS CLOSE TO FREEZING. MEANWHILE...OTHER AREAS NORTH OF THE BOUNDARY GENERALLY ARE IN THE MID 30S TO MID 40S. SOUTH OF THE BOUNDARY...TEMPS ARE IN THE 40S ACROSS THE LOWER ELEVATIONS...AND 50S OVER THE HIGH TERRAIN. THESE WARM TEMPS OVER THE HIGHER ELEVATIONS WILL START TO LOWER OVER THE NEXT FEW HOURS...AS FORECAST MODEL SOUNDINGS SHOWS THE IMPRESSIVE WARM NOSE AT AROUND 900-950 HPA IS FINALLY BEING PUSHED AWAY FROM THE REGION THANKS A STRONG SW FLOW ALOFT. STILL...THE AIR MOVING IN THIS MORNING ISN/T OVERLY CHILLY JUST YET...AS OUR REGION IS BEING INFLUENCED BY A STRONG MEDIRONDAL FLOW AHEAD OF A DEEP UPPER LEVEL TROUGH SITUATED OVER THE CENTRAL PORTION OF THE US. IN ADDITION...THIS FLOW IS CONTINUING TO TRANSPORT PLENTY OF MID/HIGH LEVEL MOISTURE STRAIGHT OUT OF PACIFIC AND GULF OF MEXICO TOWARDS OUR AREA. PWATS WILL CONTINUE TO BE ABOVE NORMAL TODAY...WITH FORECASTED VALUES EXPECTED TO BE AROUND AN INCH...WHICH IS ABOUT 2 STD ABOVE NORMAL. DURING THE DAY TODAY...AN AREA OF LOW PRESSURE /DEVELOPING ACROSS THE SOUTHEAST US EARLY THIS MORNING/ WILL RIDE NORTHWARD ALONG THE EASTERN SEABOARD. REGIONAL RADAR ALREADY SHOWS A SOLID AREA OF STEADY RAIN AHEAD OF THIS DEVELOPING SYSTEM OVER THE MID ATLANTIC STATES...AND THIS WILL BE RIDING FROM SOUTHWEST TO NORTHEAST ACROSS THE REGION TODAY. THE 00Z NAM/GFS/ECMWF AND 05Z 3KM HRRR ALL SHOW THIS PRECIP MOVING FROM SOUTHWEST TO NORTHEAST ACROSS OUR REGION BETWEEN JUST SHORTLY BEFORE SUNRISE AND THROUGH THE MORNING HOURS. THE BEST CHC FOR PRECIP WILL BE ACROSS THE SOUTHERN AND EASTERN PORTION OF THE CWA...WHERE UP TO AROUND A HALF INCH OF RAIN WILL FALL FOR LITCHFIELD COUNTY. PRECIP WILL FALL MAINLY IN THE FORM OF LIQUID RAIN. WITH CONTINUED MARGINAL TEMPS IN THE LAKE GEORGE/SARATOGA REGION...IT/S POSSIBLE THAT THERE MAY INITIALLY BE SOME SPOTTY FREEZING RAIN ONCE THE PRECIP MOVES IN...BUT TEMPS SHOULD WARM UP ENOUGH TO AVOID A PROLONGED PERIOD OF FREEZING RAIN THERE. OTHERWISE...THE ONLY OTHER PLACE THERE COULD BE SOME WINTRY PRECIP IS THE FAR NORTHWESTERN ADIRONDACKS...WHERE COLDER AIR SNEAKING IN ALOFT MAY ALLOW FOR THE PRECIP TO CHANGEOVER TO SLEET/SNOW. LITTLE QPF IS EXPECTED THAT FAR NW...SO ANY ACCUMULATION WILL BE LIMITED TO JUST A COATING. MOST AREAS LOOK TO SEE MAX TEMPS IN THE MORNING HOURS...WITH TEMPS RANGING FROM THE MID 30S IN THE ADIRONDACKS TO THE MID 50S IN THE MID HUDSON VALLEY AND NW CT. MOST TEMPS WILL HOLD STEADY THIS MORNING...ALTHOUGH THE CAD IN THE LAKE GEORGE/SARATOGA AREA SHOULD GIVE WAY ENOUGH FOR TEMPS THERE TO RISE TOWARDS THE UPPER 30S TO LOW 40S BY THE LATE MORNING HOURS. BY THE AFTN...STEADY PRECIP WILL BE MOVING ACROSS NEW ENGLAND...AND THERE WILL BE JUST A FEW LINGERING SHOWERS...MAINLY ACROSS THE HIGHER ELEVATIONS. WITH COLDER AIR SURGING IN ON WESTERLY WINDS...TEMPS WILL TUMBLE ACROSS MOST AREAS DURING THE AFTN HOURS...FALLING FROM THE 40S INTO THE 30S ACROSS MUCH OF THE REGION. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... GENERALLY THE MODEL SUITE (GEM/GFS/NAM/ECMWF) IS IN AGREEMENT DURING THIS PERIOD...WITH A SERIES OF FAST MOVING 500HPA SHORT WVS AND MODEST SFC SYSTEMS...IN A RELATIVELY MOISTURE STARVED ENVIRONMENT. THE STRONGEST OF THE SHORT WVS MVS FM UPPER GRTLKS TNGT...CROSSES THE REGION TUES...AND EXISTS THE RGN TUES NT. AS FCA IS IN SFC GRADIENT BTWN DEPARTING SFC LOW IN GULF OF MAINE AND SFC HIGH BUILDING SE FM ONTARIO WINDS AND CAA WILL INCR TNGT. CLOUDS AND PCPN ALONG COAST WILL BE GONE BY EVENING W/CLEARING. LATER AT NIGHT CLOUDS AND SCT -SHSN WILL INCR MAINLY W PRTNS OF AREA AS 500HPA SHORT WV AND 2NDRY CDFNT APPROACH FM GRTLKS. CHRISTMAS EVE THE 500HPA TROF WILL CROSS THE RGN IN CAA...AND BRING VRBL CLOUDS AND SCT -SHSN...HWVR WITH SFC FLOW N-NE ANY INTERACTIONS W/GRTLKS WILL BE TO AREAS WELL TO OUR WEST. 500HPA TROF EXITS RGN TUES EVNG...AS ARCTIC SFC HIGH DROPS INTO E GRTLKS AND NYS OVERNIGHT. IDEAL RADIATION CONDS WILL SET UP AS SKIES CLEAR...WINDS BCM LIGHT AND ONE OF THE LONGEST NIGHTS OF THE YEAR WITH ALMOST 15 HOURS OF DARKNESS...WILL ALLOW TEMPS TO PLUNGE. WHERE SNOW COVER REMAINS THE PLUNGE WILL BE EVEN GREATER WITH LOWS BY CHRISTMAS MORNING FALLING TO -20F IN PARTS OF THE ADRDKS...WHILE FURTHER SOUTH LOWS WILL BE CLOSER TO +10F. AFTER A CHILLY START CHRISTMAS DAY 500HPA RIDGE AND SFC HIGH SLIDE OFFSHORE...AND TEMPS REBOUND TO TEENS AND 20S. BY AFTN THE PATTERN THAT WILL DOMINATE THE REST OF THE WEEK AND MAYBE THE YEAR WILL SET UP. RGN IS IN FAST W TO NW 500HPA...AND A PARADE OF SHRT WAVES AND CLIPPER TYPE LOWS MOVE THROUGH. THE FIRST OF THESE MOVES INTO THE GRTLKS CHRISTMAS DAY...WITH SOME INCRG CLOUDS IN THE AFTN. WED NT ITS WK SFC SYSTEM PUSHES A WMFNT THRU RGN AND A CDFNT THU. ITS MAIN IMPACTS WILL NE INCR CLOUDS WED NT WITH A SCT -SHSN THU AND A BRIEF LK EFFECT RESPONSE THU AND THU EVNG INTO W MHWK VLY AND W ADRNDKS. LATER THU NT SFC HIGH WILL RIDGE INTO RGN AS NEXT SHORT WV TEES UP OVER MICHIGAN. TEMPS THU WILL RETURN TO NR NORMALS && .LONG TERM /FRIDAY THROUGH SUNDAY/... THE LAST WEEKEND OF 2013 WILL KEEP THE FAST 500 HPA FLOW ACROSS N TIER OF USA...AND THE PARADE OF SHORT WVS AND WEAK SYSTEMS. WK SFC HIGH CRESTS ACROSS GRTLKS FRI...AS ANOTHER 500HPA SHORT WV RACES THROUGH. DURING FRI EVENING A WK WMFNT SETS UP FM NW TO SE W OF FCA. IN SPITE OF ALL THESE FEATURES SO LITTLE MOISTURE NOT MUCH MORE THAN VRBL CLOUDS AND SCT FLURRIES N TIER. SAT A STRONGER SHORT WV MVS INTO W GRTLKS WITH CLIPPER TYPE SFC LOW. BY EVENING IT PUSHES WMFNT INTO FCA AND OVERRUNING CLOUDS BCM MORE EXTENSIVE UPSTREAM AND SPILL SE INTO FCA. BUT IN THIS CASE BULK OF DYNAMICS AND MOISTURE REMAIN N IN CANADA AND MAINLY CLOUDS AND CHC -SN IN FAR N TIER OF FCA. BY END OF PD STRONG CDFNT EITHER MOVES THROUGH...(GFS) OR IS ABOUT TO (ECWMF) ABOUT 12 HOUR DIFFERENCE AND NOT AS COLD AN AIR MASS ON ECMWF. OTHER THAN THIS SLIGHT TIMING DIFFERENCE THE GFS/ECMWF ARE IN VERY GOOD AGREEMENT DURING THE EFP. THIS IS SAME SCENARIO REFLECTED IN HPC GUID...AND THEY LEAN TWRD THE FAST GFS CDFNT SCENARIO. IN ANY CASE BY END OF PERIOD TEMPS DROP TO BLOW NORMALS. GEFS PLUMES HAVE A FEW MEMBERS WITH 0.10 TO 0.20 QPF SIGNAL IN THE THU/FRI TIME PERIOD...OTHERWISE MOST ARE FLAT LINED TILL NEXT MONDAY IN WHEN ABOUT HALF START SHOWING A 2-4 INCH TYPE SNOW EVENT...WHICH NONE OF THE DETERMINISTIC MODELS DO. SINCE THERE`S LITTLE DIVERGENCE IN THE GUID DURING THIS PERIOD WILL POPULATE WITH HPC. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... FLYING CONDITIONS VARYING QUITE A BIT ACROSS THE AREA...WITH KGFL SOCKED IN WITH LIFR FOG AND LOW STRATUS ON THE COLD SIDE OF A FRONTAL BOUNDARY...WHILE KPOU/KPSF ARE SOUTH OF THIS FRONT WITH VFR CONDITIONS. KALB IS RIGHT ON THE BORDER NEAR THE BOUNDARY...AND HAS SEEN VFR CONDITIONS DROP TO MVFR. ALL SITES ARE SEEING LIGHT TO CALM WINDS AND THIS LOOKS TO CONTINUE THROUGH THE OVERNIGHT HOURS. A WAVE OF LOW PRESSURE WILL LIFT NORTHEASTWARD ALONG THE FRONTAL BOUNDARY WHICH WILL RESULT IN ANOTHER ROUND OF LIGHT STEADY RAINFALL STARTING BETWEEN 08Z-10Z. CONDITIONS ARE EXPECTED TO LOWER TO IFR BEFORE 12Z AT ALL TERMINALS. WILL CONTINUE TO MENTION IFR CONDITIONS THROUGH AROUND 18Z OR 19Z...WITH RAIN THEN ENDING AND DRIER AIR STARTING TO WORK THEREAFTER WITH IMPROVING CONDITIONS. ALL SITES LOOK TO BE VFR BY THE EVENING HOURS...WITH A WESTERLY BREEZE DEVELOPING. A FEW GUSTS TOWARDS 20 KTS WILL BE POSSIBLE FOR KALB/KPSF FOR MONDAY EVENING. OUTLOOK... TUESDAY NIGHT AND CHRISTMAS DAY: NO OPERATIONAL IMPACT. NO SIG WX. WEDNESDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. THURSDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN. THURSDAY NIGHT THROUGH SATURDAY: NO OPERATIONAL IMPACT. NO SIG WX. && .HYDROLOGY... LOW PRESSURE WILL RIPPLE UP THE EASTERN SEABOARD TODAY...BRINGING UP TO A HALF INCH OF QPF TO AREAS SOUTH AND EAST OF ALBANY...WITH THE GREATEST AMOUNTS IN LITCHFIELD AND DUTCHESS COUNTIES. THIS WILL ADD TO STREAM FLOWS AND WITHIN BANK RISES IN THESE AREAS. HOWEVER EVEN THOUGH THEY HAD TOTAL SNOW MELT...THEY HAD LITTLE RAINFALL WITH THE PREVIOUS SYSTEM...AND FLOODING IS NOT EXPECTED. COLDER DRIER AIR WILL FILTER BACK INTO THE REGION TONIGHT...WITH MUCH COLDER TEMPERATURES AND MAINLY DRY CONDITIONS THE REST OF THE WEEK. THERE MAY BE SCATTERED SNOW SHOWERS...BUT OF LITTLE CONSEQUENCE TO RIVERS AND STREAMS. STREAM FLOWS WILL SLOW AS RUN OFF AND SNOW MELT END. ICE FORMATION WILL START ANEW BY CHRISTMAS. 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...SNYDER NEAR TERM...FRUGIS SHORT TERM...SNYDER LONG TERM...SNYDER AVIATION...FRUGIS HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS ALBANY NY
329 AM EST MON DEC 23 2013 .SYNOPSIS... LOW PRESSURE WILL MOVE UP THE SEASON SEABOARD TODAY...BRINGING ONE MORE ROUND OF RAIN TO SOUTHERN NEW ENGLAND AND IN NEW YORK FROM THE CAPITAL DISTRICT SOUTH. IN ITS WAKE COLD AIR WILL FILTER INTO OUR REGION THIS AFTERNOON AS WINDS INCREASE. EVEN COLDER AIR WILL MOVE INTO THE REGION AS HIGH PRESSURE MOVES FROM ONTARIO TONIGHT TO NEW YORK AND NEW ENGLAND CHRISTMAS DAY. THE REST OF THE WEEK WILL FEATURE A SERIES OF WEAK FAST MOVING WEATHER SYSTEMS...WITH VARIABLE CLOUDINESS...SCATTERED SNOW SHOWERS AND SEASONABLE TEMPERATURES. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 300 AM EST...NEARLY STATIONARY FRONTAL BOUNDARY CONTINUES TO BE SITUATED FROM WEST TO EAST ACROSS THE CENTRAL PORTION OF THE CWA EARLY THIS MORNING. TO THE NORTH OF THIS BOUNDARY...IMPRESSIVE CAD CONTINUES ACROSS THE LAKE GEORGE/SARATOGA REGION...WITH TEMPS CLOSE TO FREEZING. MEANWHILE...OTHER AREAS NORTH OF THE BOUNDARY GENERALLY ARE IN THE MID 30S TO MID 40S. SOUTH OF THE BOUNDARY...TEMPS ARE IN THE 40S ACROSS THE LOWER ELEVATIONS...AND 50S OVER THE HIGH TERRAIN. THESE WARM TEMPS OVER THE HIGHER ELEVATIONS WILL START TO LOWER OVER THE NEXT FEW HOURS...AS FORECAST MODEL SOUNDINGS SHOWS THE IMPRESSIVE WARM NOSE AT AROUND 900-950 HPA IS FINALLY BEING PUSHED AWAY FROM THE REGION THANKS A STRONG SW FLOW ALOFT. STILL...THE AIR MOVING IN THIS MORNING ISN/T OVERLY CHILLY JUST YET...AS OUR REGION IS BEING INFLUENCED BY A STRONG MEDIRONDAL FLOW AHEAD OF A DEEP UPPER LEVEL TROUGH SITUATED OVER THE CENTRAL PORTION OF THE US. IN ADDITION...THIS FLOW IS CONTINUING TO TRANSPORT PLENTY OF MID/HIGH LEVEL MOISTURE STRAIGHT OUT OF PACIFIC AND GULF OF MEXICO TOWARDS OUR AREA. PWATS WILL CONTINUE TO BE ABOVE NORMAL TODAY...WITH FORECASTED VALUES EXPECTED TO BE AROUND AN INCH...WHICH IS ABOUT 2 STD ABOVE NORMAL. DURING THE DAY TODAY...AN AREA OF LOW PRESSURE /DEVELOPING ACROSS THE SOUTHEAST US EARLY THIS MORNING/ WILL RIDE NORTHWARD ALONG THE EASTERN SEABOARD. REGIONAL RADAR ALREADY SHOWS A SOLID AREA OF STEADY RAIN AHEAD OF THIS DEVELOPING SYSTEM OVER THE MID ATLANTIC STATES...AND THIS WILL BE RIDING FROM SOUTHWEST TO NORTHEAST ACROSS THE REGION TODAY. THE 00Z NAM/GFS/ECMWF AND 05Z 3KM HRRR ALL SHOW THIS PRECIP MOVING FROM SOUTHWEST TO NORTHEAST ACROSS OUR REGION BETWEEN JUST SHORTLY BEFORE SUNRISE AND THROUGH THE MORNING HOURS. THE BEST CHC FOR PRECIP WILL BE ACROSS THE SOUTHERN AND EASTERN PORTION OF THE CWA...WHERE UP TO AROUND A HALF INCH OF RAIN WILL FALL FOR LITCHFIELD COUNTY. PRECIP WILL FALL MAINLY IN THE FORM OF LIQUID RAIN. WITH CONTINUED MARGINAL TEMPS IN THE LAKE GEORGE/SARATOGA REGION...IT/S POSSIBLE THAT THERE MAY INITIALLY BE SOME SPOTTY FREEZING RAIN ONCE THE PRECIP MOVES IN...BUT TEMPS SHOULD WARM UP ENOUGH TO AVOID A PROLONGED PERIOD OF FREEZING RAIN THERE. OTHERWISE...THE ONLY OTHER PLACE THERE COULD BE SOME WINTRY PRECIP IS THE FAR NORTHWESTERN ADIRONDACKS...WHERE COLDER AIR SNEAKING IN ALOFT MAY ALLOW FOR THE PRECIP TO CHANGEOVER TO SLEET/SNOW. LITTLE QPF IS EXPECTED THAT FAR NW...SO ANY ACCUMULATION WILL BE LIMITED TO JUST A COATING. MOST AREAS LOOK TO SEE MAX TEMPS IN THE MORNING HOURS...WITH TEMPS RANGING FROM THE MID 30S IN THE ADIRONDACKS TO THE MID 50S IN THE MID HUDSON VALLEY AND NW CT. MOST TEMPS WILL HOLD STEADY THIS MORNING...ALTHOUGH THE CAD IN THE LAKE GEORGE/SARATOGA AREA SHOULD GIVE WAY ENOUGH FOR TEMPS THERE TO RISE TOWARDS THE UPPER 30S TO LOW 40S BY THE LATE MORNING HOURS. BY THE AFTN...STEADY PRECIP WILL BE MOVING ACROSS NEW ENGLAND...AND THERE WILL BE JUST A FEW LINGERING SHOWERS...MAINLY ACROSS THE HIGHER ELEVATIONS. WITH COLDER AIR SURGING IN ON WESTERLY WINDS...TEMPS WILL TUMBLE ACROSS MOST AREAS DURING THE AFTN HOURS...FALLING FROM THE 40S INTO THE 30S ACROSS MUCH OF THE REGION. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... GENERALLY THE MODEL SUITE (GEM/GFS/NAM/ECMWF) IS IN AGREEMENT DURING THIS PERIOD...WITH A SERIES OF FAST MOVING 500HPA SHORT WVS AND MODEST SFC SYSTEMS...IN A RELATIVELY MOISTURE STARVED ENVIRONMENT. THE STRONGEST OF THE SHORT WVS MVS FM UPPER GRTLKS TNGT...CROSSES THE REGION TUES...AND EXISTS THE RGN TUES NT. AS FCA IS IN SFC GRADIENT BTWN DEPARTING SFC LOW IN GULF OF MAINE AND SFC HIGH BUILDING SE FM ONTARIO WINDS AND CAA WILL INCR TNGT. CLOUDS AND PCPN ALONG COAST WILL BE GONE BY EVENING W/CLEARING. LATER AT NIGHT CLOUDS AND SCT -SHSN WILL INCR MAINLY W PRTNS OF AREA AS 500HPA SHORT WV AND 2NDRY CDFNT APPROACH FM GRTLKS. CHRISTMAS EVE THE 500HPA TROF WILL CROSS THE RGN IN CAA...AND BRING VRBL CLOUDS AND SCT -SHSN...HWVR WITH SFC FLOW N-NE ANY INTERACTIONS W/GRTLKS WILL BE TO AREAS WELL TO OUR WEST. 500HPA TROF EXITS RGN TUES EVNG...AS ARCTIC SFC HIGH DROPS INTO E GRTLKS AND NYS OVERNIGHT. IDEAL RADIATION CONDS WILL SET UP AS SKIES CLEAR...WINDS BCM LIGHT AND ONE OF THE LONGEST NIGHTS OF THE YEAR WITH ALMOST 15 HOURS OF DARKNESS...WILL ALLOW TEMPS TO PLUNGE. WHERE SNOW COVER REMAINS THE PLUNGE WILL BE EVEN GREATER WITH LOWS BY CHRISTMAS MORNING FALLING TO -20F IN PARTS OF THE ADRDKS...WHILE FURTHER SOUTH LOWS WILL BE CLOSER TO +10F. AFTER A CHILLY START CHRISTMAS DAY 500HPA RIDGE AND SFC HIGH SLIDE OFFSHORE...AND TEMPS REBOUND TO TEENS AND 20S. BY AFTN THE PATTERN THAT WILL DOMINATE THE REST OF THE WEEK AND MAYBE THE YEAR WILL SET UP. RGN IS IN FAST W TO NW 500HPA...AND A PARADE OF SHRT WAVES AND CLIPPER TYPE LOWS MOVE THROUGH. THE FIRST OF THESE MOVES INTO THE GRTLKS CHRISTMAS DAY...WITH SOME INCRG CLOUDS IN THE AFTN. WED NT ITS WK SFC SYSTEM PUSHES A WMFNT THRU RGN AND A CDFNT THU. ITS MAIN IMPACTS WILL NE INCR CLOUDS WED NT WITH A SCT -SHSN THU AND A BRIEF LK EFFECT RESPONSE THU AND THU EVNG INTO W MHWK VLY AND W ADRNDKS. LATER THU NT SFC HIGH WILL RIDGE INTO RGN AS NEXT SHORT WV TEES UP OVER MICHIGAN. TEMPS THU WILL RETURN TO NR NORMALS && .LONG TERM /FRIDAY THROUGH SUNDAY/... THE LAST WEEKEND OF 2013 WILL KEEP THE FAST 500 HPA FLOW ACROSS N TIER OF USA...AND THE PARADE OF SHORT WVS AND WEAK SYSTEMS. WK SFC HIGH CRESTS ACROSS GRTLKS FRI...AS ANOTHER 500HPA SHORT WV RACES THROUGH. DURING FRI EVENING A WK WMFNT SETS UP FM NW TO SE W OF FCA. IN SPITE OF ALL THESE FEATURES SO LITTLE MOISTURE NOT MUCH MORE THAN VRBL CLOUDS AND SCT FLURRIES N TIER. SAT A STRONGER SHORT WV MVS INTO W GRTLKS WITH CLIPPER TYPE SFC LOW. BY EVENING IT PUSHES WMFNT INTO FCA AND OVERRUNING CLOUDS BCM MORE EXTENSIVE UPSTREAM AND SPILL SE INTO FCA. BUT IN THIS CASE BULK OF DYNAMICS AND MOISTURE REMAIN N IN CANADA AND MAINLY CLOUDS AND CHC -SN IN FAR N TIER OF FCA. BY END OF PD STRONG CDFNT EITHER MOVES THROUGH...(GFS) OR IS ABOUT TO (ECWMF) ABOUT 12 HOUR DIFFERENCE AND NOT AS COLD AN AIR MASS ON ECMWF. OTHER THAN THIS SLIGHT TIMING DIFFERENCE THE GFS/ECMWF ARE IN VERY GOOD AGREEMENT DURING THE EFP. THIS IS SAME SCENARIO REFLECTED IN HPC GUID...AND THEY LEAN TWRD THE FAST GFS CDFNT SCENARIO. IN ANY CASE BY END OF PERIOD TEMPS DROP TO BLOW NORMALS. GEFS PLUMES HAVE A FEW MEMBERS WITH 0.10 TO 0.20 QPF SIGNAL IN THE THU/FRI TIME PERIOD...OTHERWISE MOST ARE FLAT LINED TILL NEXT MONDAY IN WHEN ABOUT HALF START SHOWING A 2-4 INCH TYPE SNOW EVENT...WHICH NONE OF THE DETERMINISTIC MODELS DO. SINCE THERE`S LITTLE DIVERGENCE IN THE GUID DURING THIS PERIOD WILL POPULATE WITH HPC. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... FLYING CONDITIONS VARYING QUITE A BIT ACROSS THE AREA...WITH KGFL SOCKED IN WITH LIFR FOG AND LOW STRATUS ON THE COLD SIDE OF A FRONTAL BOUNDARY...WHILE KPOU/KPSF ARE SOUTH OF THIS FRONT WITH VFR CONDITIONS. KALB IS RIGHT ON THE BORDER NEAR THE BOUNDARY...AND HAS SEEN VFR CONDITIONS DROP TO MVFR. ALL SITES ARE SEEING LIGHT TO CALM WINDS AND THIS LOOKS TO CONTINUE THROUGH THE OVERNIGHT HOURS. A WAVE OF LOW PRESSURE WILL LIFT NORTHEASTWARD ALONG THE FRONTAL BOUNDARY WHICH WILL RESULT IN ANOTHER ROUND OF LIGHT STEADY RAINFALL STARTING BETWEEN 08Z-10Z. CONDITIONS ARE EXPECTED TO LOWER TO IFR BEFORE 12Z AT ALL TERMINALS. WILL CONTINUE TO MENTION IFR CONDITIONS THROUGH AROUND 18Z OR 19Z...WITH RAIN THEN ENDING AND DRIER AIR STARTING TO WORK THEREAFTER WITH IMPROVING CONDITIONS. ALL SITES LOOK TO BE VFR BY THE EVENING HOURS...WITH A WESTERLY BREEZE DEVELOPING. A FEW GUSTS TOWARDS 20 KTS WILL BE POSSIBLE FOR KALB/KPSF FOR MONDAY EVENING. OUTLOOK... MONDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN. TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. TUESDAY NIGHT TO FRIDAY: NO OPERATIONAL IMPACT. NO SIG WX. && .HYDROLOGY... LOW PRESSURE WILL RIPPLE UP THE EASTERN SEABOARD TODAY...BRINGING UP TO A HALF INCH OF QPF TO AREAS SOUTH AND EAST OF ALBANY...WITH THE GREATEST AMOUNTS IN LITCHFIELD AND DUTCHESS COUNTIES. THIS WILL ADD TO STREAM FLOWS AND WITHIN BANK RISES IN THESE AREAS. HOWEVER EVEN THOUGH THEY HAD TOTAL SNOW MELT...THEY HAD LITTLE RAINFALL WITH THE PREVIOUS SYSTEM...AND FLOODING IS NOT EXPECTED. COLDER DRIER AIR WILL FILTER BACK INTO THE REGION TONIGHT...WITH MUCH COLDER TEMPERATURES AND MAINLY DRY CONDITIONS THE REST OF THE WEEK. THERE MAY BE SCATTERED SNOW SHOWERS...BUT OF LITTLE CONSEQUENCE TO RIVERS AND STREAMS. STREAM FLOWS WILL SLOW AS RUN OFF AND SNOW MELT END. ICE FORMATION WILL START ANEW BY CHRISTMAS. 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...SNYDER NEAR TERM...FRUGIS SHORT TERM...SNYDER LONG TERM...SNYDER AVIATION...FRUGIS HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS ALBANY NY
157 AM EST MON DEC 23 2013 .SYNOPSIS... LOW PRESSURE WILL MOVE UP THE SEASON SEABOARD TODAY...BRINGING ONE MORE ROUND OF RAIN TO SOUTHERN NEW ENGLAND AND IN NEW YORK FROM THE CAPITAL DISTRICT SOUTH. IN ITS WAKE COLD AIR WILL FILTER INTO OUR REGION THIS AFTERNOON AS WINDS INCREASE. EVEN COLDER AIR WILL MOVE INTO THE REGION AS HIGH PRESSURE MOVES FROM ONTARIO TONIGHT TO NEW YORK AND NEW ENGLAND CHRISTMAS DAY. THE REST OF THE WEEK WILL FEATURE A SERIES OF WEAK FAST MOVING WEATHER SYSTEMS...WITH VARIABLE CLOUDINESS...SCATTERED SNOW SHOWERS AND SEASONABLE TEMPERATURES. && .NEAR TERM /THROUGH TODAY/... AS OF 1220 AM EST...TEMPERATURES CONTINUE TO BE HIGHLY VARIABLE ACROSS THE REGION...AS A NEARLY STATIONARY BOUNDARY IS SITUATED ACROSS CENTRAL PARTS OF THE AREA. TEMPS CONTINUE TO BE IN THE UPPER 50S ACROSS SOUTHERN AREAS...WITH TEMPS NEAR FREEZING IN THE LAKE GEORGE/SARATOGA REGION...AS THE COLD NORTHERLY FLOW CONTINUES ACROSS THAT REGION. TEMPS IN THE CAPITAL REGION HAVE BEEN RATHER VARIABLE...AND HAVE CURRENTLY DROPPED INTO THE 40S. NO PRECIP IS CURRENTLY OCCURRING OVER OUR REGION AND LOCAL AND UPSTREAM RADARS SHOW VERY LITTLE. HOWEVER...A WAVE OF LOW PRESSURE IS FORECAST TO LIFT NORTHEASTWARD ALONG THE FRONTAL BOUNDARY LATE TONIGHT INTO MONDAY...BRINGING ANOTHER ROUND OF RAINFALL TO AREAS MAINLY FROM THE CAPITAL REGION SOUTH AND EAST. THE 01Z 3KM HRRR CONTINUES TO SHOW PRECIP DEVELOPING AND EXPANDING ACROSS OUR REGION AFTER ABOUT 08Z-09Z. HAVE ADJUSTED POPS ACCORDING TO THE LATEST GUIDANCE...WHICH HAS RAIN DEVELOPING FROM SOUTHWEST TO NORTHEAST LATE TONIGHT. MILD TEMPERATURES SOUTH AND EAST OF THE CAPITAL REGION WILL SLOWLY DROP LATE TONIGHT AS THE FRONTAL BOUNDARY EASES SOUTHWARD. FURTHER NORTH...TEMPS WILL GENERALLY HOLD STEADY THROUGH THE REMAINDER OF THE OVERNIGHT. AFOREMENTIONED DISTURBANCE LOOKS TO BRING ONE MORE ROUND OF RAIN...MAINLY FROM ALBANY AND POINTS SOUTHWARD ON MONDAY. WE ARE LOOKING FOR A QUARTER TO HALF AN INCH OF RAINFALL WITH THIS WAVE WITH ONLY A CHANCE OF RAIN NORTH AND WEST OF ALBANY. TEMPERATURES WILL SLOWLY COOL OFF AS THE COLD FRONT CONTINUES TO SLIP SLOWLY SOUTH AND EAST OF OUR FORECAST AREA. H850 TEMPERATURES...WHICH ROSE OVER +10C OVER MUCH OF OUR AREA ON SUNDAY...WILL COOL BACK TO MUCH MORE NORMAL DECEMBER LEVELS...BELOW 0C BY LATE MONDAY. ANY LEFTOVER PRECIPITATION SHOULD CHANGE BACK TO SNOW NORTH AND WEST OF ALBANY BY LATE MONDAY...PROBABLY NOT FROM ALBANY SOUTHWARD. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... GENERALLY THE MODEL SUITE (GEM/GFS/NAM/ECMWF) IS IN AGREEMENT DURING THIS PERIOD...WITH A SERIES OF FAST MOVING 500HPA SHORT WVS AND MODEST SFC SYSTEMS...IN A RELATIVELY MOISTURE STARVED ENVIRONMENT. THE STRONGEST OF THE SHORT WVS MVS FM UPPER GRTLKS TNGT...CROSSES THE REGION TUES...AND EXISTS THE RGN TUES NT. AS FCA IS IN SFC GRADIENT BTWN DEPARTING SFC LOW IN GULF OF MAINE AND SFC HIGH BUILDING SE FM ONTARIO WINDS AND CAA WILL INCR TNGT. CLOUDS AND PCPN ALONG COAST WILL BE GONE BY EVENING W/CLEARING. LATER AT NIGHT CLOUDS AND SCT -SHSN WILL INCR MAINLY W PRTNS OF AREA AS 500HPA SHORT WV AND 2NDRY CDFNT APPROACH FM GRTLKS. CHRISTMAS EVE THE 500HPA TROF WILL CROSS THE RGN IN CAA...AND BRING VRBL CLOUDS AND SCT -SHSN...HWVR WITH SFC FLOW N-NE ANY INTERACTIONS W/GRTLKS WILL BE TO AREAS WELL TO OUR WEST. 500HPA TROF EXITS RGN TUES EVNG...AS ARCTIC SFC HIGH DROPS INTO E GRTLKS AND NYS OVERNIGHT. IDEAL RADIATION CONDS WILL SET UP AS SKIES CLEAR...WINDS BCM LIGHT AND ONE OF THE LONGEST NIGHTS OF THE YEAR WITH ALMOST 15 HOURS OF DARKNESS...WILL ALLOW TEMPS TO PLUNGE. WHERE SNOW COVER REMAINS THE PLUNGE WILL BE EVEN GREATER WITH LOWS BY CHRISTMAS MORNING FALLING TO -20F IN PARTS OF THE ADRDKS...WHILE FURTHER SOUTH LOWS WILL BE CLOSER TO +10F. AFTER A CHILLY START CHRISTMAS DAY 500HPA RIDGE AND SFC HIGH SLIDE OFFSHORE...AND TEMPS REBOUND TO TEENS AND 20S. BY AFTN THE PATTERN THAT WILL DOMINATE THE REST OF THE WEEK AND MAYBE THE YEAR WILL SET UP. RGN IS IN FAST W TO NW 500HPA...AND A PARADE OF SHRT WAVES AND CLIPPER TYPE LOWS MOVE THROUGH. THE FIRST OF THESE MOVES INTO THE GRTLKS CHRISTMAS DAY...WITH SOME INCRG CLOUDS IN THE AFTN. WED NT ITS WK SFC SYSTEM PUSHES A WMFNT THRU RGN AND A CDFNT THU. ITS MAIN IMPACTS WILL NE INCR CLOUDS WED NT WITH A SCT -SHSN THU AND A BRIEF LK EFFECT RESPONSE THU AND THU EVNG INTO W MHWK VLY AND W ADRNDKS. LATER THU NT SFC HIGH WILL RIDGE INTO RGN AS NEXT SHORT WV TEES UP OVER MICHIGAN. TEMPS THU WILL RETURN TO NR NORMALS && .LONG TERM /FRIDAY THROUGH SUNDAY/... THE EXTENDED PERIOD CONTINUES TO LOOK MAINLY DRY...WITH THE ONLY CHANCE FOR MEASURABLE PRECIPITATION BEING IN THE FORM OF LAKE EFFECT SNOW SHOWERS IN PORTIONS OF THE WESTERN ADIRONDACKS...THROUGH FRIDAY NIGHT. A WEAK CLIPPER-LIKE LOW IS EXPECTED TO PASS TO OUR NORTH LATE SUNDAY...PROVIDING LITTLE IN THE WAY OF PRECIPITATION. TEMPERATURES DURING THIS PERIOD WILL BE NR TO SLIGHT ABV NORMALS. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... FLYING CONDITIONS VARYING QUITE A BIT ACROSS THE AREA...WITH KGFL SOCKED IN WITH LIFR FOG AND LOW STRATUS ON THE COLD SIDE OF A FRONTAL BOUNDARY...WHILE KPOU/KPSF ARE SOUTH OF THIS FRONT WITH VFR CONDITIONS. KALB IS RIGHT ON THE BORDER NEAR THE BOUNDARY...AND HAS SEEN VFR CONDITIONS DROP TO MVFR. ALL SITES ARE SEEING LIGHT TO CALM WINDS AND THIS LOOKS TO CONTINUE THROUGH THE OVERNIGHT HOURS. A WAVE OF LOW PRESSURE WILL LIFT NORTHEASTWARD ALONG THE FRONTAL BOUNDARY WHICH WILL RESULT IN ANOTHER ROUND OF LIGHT STEADY RAINFALL STARTING BETWEEN 08Z-10Z. CONDITIONS ARE EXPECTED TO LOWER TO IFR BEFORE 12Z AT ALL TERMINALS. WILL CONTINUE TO MENTION IFR CONDITIONS THROUGH AROUND 18Z OR 19Z...WITH RAIN THEN ENDING AND DRIER AIR STARTING TO WORK THEREAFTER WITH IMPROVING CONDITIONS. ALL SITES LOOK TO BE VFR BY THE EVENING HOURS...WITH A WESTERLY BREEZE DEVELOPING. A FEW GUSTS TOWARDS 20 KTS WILL BE POSSIBLE FOR KALB/KPSF FOR MONDAY EVENING. OUTLOOK... MONDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN. TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. TUESDAY NIGHT TO FRIDAY: NO OPERATIONAL IMPACT. NO SIG WX. && .HYDROLOGY... LOW PRESSURE WILL RIPPLE UP THE EASTERN SEABOARD TODAY...BRINGING UP TO A HALF INCH OF QPF TO AREAS SOUTH AND EAST OF ALBANY...WITH THE GREATEST AMOUNTS IN LITCHFIELD AND DUTCHESS COUNTIES. THIS WILL ADD TO STREAM FLOWS AND WITHIN BANK RISES IN THESE AREAS. HOWEVER EVEN THOUGH THEY HAD TOTAL SNOW MELT...THEY HAD LITTLE RAINFALL WITH THE PREVIOUS SYSTEM...AND FLOODING IS NOT EXPECTED. COLDER DRIER AIR WILL FILTER BACK INTO THE REGION TONIGHT...WITH MUCH COLDER TEMPERATURES AND MAINLY DRY CONDITIONS THE REST OF THE WEEK. THERE MAY BE SCATTERED SNOW SHOWERS...BUT OF LITTLE CONSEQUENCE TO RIVERS AND STREAMS. STREAM FLOWS WILL SLOW AS RUN OFF AND SNOW MELT END. ICE FORMATION WILL START ANEW BY CHRISTMAS. 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...SNYDER NEAR TERM...FRUGIS/HWJIV/JPV SHORT TERM...SNYDER LONG TERM...ELH AVIATION...FRUGIS HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS ALBANY NY
1220 AM EST MON DEC 23 2013 .SYNOPSIS... A NEARLY STATIONARY FRONT FROM CENTRAL NEW YORK TO THE MAINE COAST WILL BEGIN TO SHIFT SLOWLY SOUTHWARD TONIGHT. ONE MORE WAVE OF LOW PRESSURE WILL RIDE ALONG IT BRINGING ONE MORE SHOT OF RAINFALL MAINLY FROM CAPITAL REGION SOUTHWARD. COLDER AIR WILL FILTER IN MONDAY NIGHT. IT WILL STAY COLD MUCH OF THE UPCOMING WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1220 AM EST...TEMPERATURES CONTINUE TO BE HIGHLY VARIABLE ACROSS THE REGION...AS A NEARLY STATIONARY BOUNDARY IS SITUATED ACROSS CENTRAL PARTS OF THE AREA. TEMPS CONTINUE TO BE IN THE UPPER 50S ACROSS SOUTHERN AREAS...WITH TEMPS NEAR FREEZING IN THE LAKE GEORGE/SARATOGA REGION...AS THE COLD NORTHERLY FLOW CONTINUES ACROSS THAT REGION. TEMPS IN THE CAPITAL REGION HAVE BEEN RATHER VARIABLE...AND HAVE CURRENTLY DROPPED INTO THE 40S. NO PRECIP IS CURRENTLY OCCURRING OVER OUR REGION AND LOCAL AND UPSTREAM RADARS SHOW VERY LITTLE. HOWEVER...A WAVE OF LOW PRESSURE IS FORECAST TO LIFT NORTHEASTWARD ALONG THE FRONTAL BOUNDARY LATE TONIGHT INTO MONDAY...BRINGING ANOTHER ROUND OF RAINFALL TO AREAS MAINLY FROM THE CAPITAL REGION SOUTH AND EAST. THE 01Z 3KM HRRR CONTINUES TO SHOW PRECIP DEVELOPING AND EXPANDING ACROSS OUR REGION AFTER ABOUT 08Z-09Z. HAVE ADJUSTED POPS ACCORDING TO THE LATEST GUIDANCE...WHICH HAS RAIN DEVELOPING FROM SOUTHWEST TO NORTHEAST LATE TONIGHT. MILD TEMPERATURES SOUTH AND EAST OF THE CAPITAL REGION WILL SLOWLY DROP LATE TONIGHT AS THE FRONTAL BOUNDARY EASES SOUTHWARD. FURTHER NORTH...TEMPS WILL GENERALLY HOLD STEADY THROUGH THE REMAINDER OF THE OVERNIGHT. && .SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY/... AFOREMENTIONED DISTURBANCE LOOKS TO BRING ONE MORE ROUND OF RAIN...MAINLY FROM ALBANY AND POINTS SOUTHWARD ON MONDAY. WE ARE LOOKING FOR A QUARTER TO HALF AN INCH OF RAINFALL WITH THIS WAVE WITH ONLY A CHANCE OF RAIN NORTH AND WEST OF ALBANY. TEMPERATURES WILL SLOWLY COOL OFF AS THE COLD FRONT CONTINUES TO SLIP SLOWLY SOUTH AND EAST OF OUR FORECAST AREA. H850 TEMPERATURES...WHICH ROSE OVER +10C OVER MUCH OF OUR AREA ON SUNDAY...WILL COOL BACK TO MUCH MORE NORMAL DECEMBER LEVELS...BELOW 0C BY LATE MONDAY. ANY LEFTOVER PRECIPITATION SHOULD CHANGE BACK TO SNOW NORTH AND WEST OF ALBANY BY LATE MONDAY...PROBABLY NOT FROM ALBANY SOUTHWARD. THE WAVE AND FRONT CLEAR THE REGION MONDAY NIGHT. COLD AIR WORKING OVER THE LAKES LOOKS TO PERHAPS TRIGGER A LAKE RESPONSE. HOWEVER THE CSTAR-RESEARCH DRIVEN KVIE INDICATED NOT MUCH CHANCE FOR A SIGNIFICANT BAND AS THE WIND SHEAR WAS TOO GREAT (WNW WIND SURFACE WSW ALOFT) AND THE CAPPING INVERSION WAS ONLY ABOUT 1KM...WHICH WOULD INHIBIT SNOW GROWTH. BOTTOM LINE...ANY LAKE EFFECT WOULD BE MINIMAL BROKEN BANDS...PRODUCING NO MORE THAN A DUSTING TO AN INCH OF SNOW ACROSS MAINLY THE CENTRAL MOHAWK VALLEY MONDAY NIGHT. MAINLY DRY ELSEWHERE...BUT TURNING QUITE A BIT COLDER...WITH LOWS BACK INTO THE 20S FROM THE ALBANY SOUTHWARD...TEENS NORTH AND WEST AND EVEN SINGLE NUMBERS ACROSS THE ADIRONDACK PARK. TUESDAY...ANOTHER MID LEVEL TROUGH WILL WORK THROUGH THE REGION INDUCING BROAD ASCENT. IT LOOKS TO HAVE LIMITED MOISTURE SO FOR NOW...ONLY WENT WITH SLIGHT CHANCES OF SNOW SHOWERS EVERYWHERE ON TUESDAY. WE WILL HAVE TO WATCH IF LATER RUNS DEVELOP A MORE SIGNIFICANT SURFACE LOW PRESSURE WITH THIS TROUGH BUT IT WAS NOT THERE ON THIS SET OF GUIDANCE. IT WILL BE EASILY COLD ENOUGH FOR ANY PRECIPITATION TO FALL AS FALL ON TUESDAY WITH HIGHS ONLY IN THE TEENS ACROSS OUR NORTHWEST ZONES...20S CENTRAL AREAS (UPPER 20S CAPITAL REGION) AND LOWER 30S SOUTH ACROSS THE MID HUDSON VALLEY AND LITCHFIELD COUNTY. CHRISTMAS EVE...HIGH PRESSURE WILL BUILD INTO THE REGION AND IT LOOKS DRY BUT COLD RIGHT INTO CHRISTMAS DAY. OVERNIGHT LOWS WILL TUMBLE TO BELOW ZERO AS LOW AS -10 ACROSS THE ADIRONDACK PARK...SINGLE NUMBERS THE REMAINDER OF NORTHERN ZONES (INCLUDING SOUTHERN VERMONT)...10-15 ALBANY SOUTHWARD. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... THE EXTENDED PERIOD CONTINUES TO LOOK MAINLY DRY...WITH THE ONLY CHANCE FOR MEASURABLE PRECIPITATION BEING IN THE FORM OF LAKE EFFECT SNOW SHOWERS IN PORTIONS OF THE WESTERN ADIRONDACKS...FROM THURSDAY NIGHT THROUGH FRIDAY NIGHT. A WEAK CLIPPER-LIKE LOW TRACKING FROM THE NORTHERN LAKES TO THE CANADIAN MARITIMES WILL BE OF LITTLE MORE CONSEQUENCE THAN PROVIDING EXTRA CLOUDINESS. ANOTHER SUCH LOW IS EXPECTED TO PASS TO OUR NORTH LATE SUNDAY...ALSO PROVIDING LITTLE IN THE WAY OF PRECIPITATION. TEMPERATURES THURSDAY WILL RANGE FROM ABOUT THE UPPER 20S IN THE ADIRONDACKS...TO THE UPPER 30S DOWN THE MID HUDSON VALLEY. HIGHS WILL BE ABOUT 3 TO 8 DEGREES LOWER ON FRIDAY...AND WILL HOLD AROUND THESE VALUES FOR SATURDAY. SUNDAY WILL BE MILDEST...WITH HIGHS FROM AROUND 30 DEGREES IN THE ADIRONDACKS...TO AROUND 40 IN THE MID HUDSON VALLEY. LOW TEMPERATURES WILL BE MAINLY FROM THE MID TEENS TO MID 20S THROUGH THE PERIOD. NORMAL HIGHS FOR ALBANY ARE AROUND FREEZING...AND NORMAL LOWS ARE IN THE UPPER TEENS. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... FLYING CONDITIONS VARYING QUITE A BIT ACROSS THE AREA...WITH KGFL SOCKED IN WITH LIFR FOG AND LOW STRATUS ON THE COLD SIDE OF A FRONTAL BOUNDARY...WHILE KPOU/KPSF ARE SOUTH OF THIS FRONT WITH VFR CONDITIONS. KALB IS RIGHT ON THE BORDER NEAR THE BOUNDARY...AND HAS SEEN VFR CONDITIONS DROP TO MVFR. ALL SITES ARE SEEING LIGHT TO CALM WINDS AND THIS LOOKS TO CONTINUE THROUGH THE OVERNIGHT HOURS. A WAVE OF LOW PRESSURE WILL LIFT NORTHEASTWARD ALONG THE FRONTAL BOUNDARY WHICH WILL RESULT IN ANOTHER ROUND OF LIGHT STEADY RAINFALL STARTING BETWEEN 08Z-10Z. CONDITIONS ARE EXPECTED TO LOWER TO IFR BEFORE 12Z AT ALL TERMINALS. WILL CONTINUE TO MENTION IFR CONDITIONS THROUGH AROUND 18Z OR 19Z...WITH RAIN THEN ENDING AND DRIER AIR STARTING TO WORK THEREAFTER WITH IMPROVING CONDITIONS. ALL SITES LOOK TO BE VFR BY THE EVENING HOURS...WITH A WESTERLY BREEZE DEVELOPING. A FEW GUSTS TOWARDS 20 KTS WILL BE POSSIBLE FOR KALB/KPSF FOR MONDAY EVENING. OUTLOOK... MONDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN. TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. TUESDAY NIGHT TO FRIDAY: NO OPERATIONAL IMPACT. NO SIG WX. && .HYDROLOGY... WE CANCELLED THE FLOOD WATCH AS THE RAIN DID NOT MATERIALIZE. THE SNOW MELT DID PRODUCE SOME SIGNIFICANT WITHIN BANKS RISE ON SOME RIVERS. UTICA DID REACH MINOR FLOOD BUT THAT WAS PARTIALLY DUE TO ON GOING CONSTRUCTION TO THE CANAL AS WELL AS RUNOFF FROM SNOWMELT. ANY SHOWER ACTIVITY TONIGHT LOOKS LIGHT AND SPOTTY...UNDER A QUARTER OF AN INCH WITH VIRTUALLY NO ADDITIONAL IMPACT EXPECTED. EVEN THOUGH VERY MILD TEMPERATURES WILL OCCUR TONIGHT SOUTH OF THE CAPITAL DISTRICT...THERE WILL BE VERY LITTLE SNOW TO MELT. FURTHER NORTH...WHERE THERE IS SNOW...TEMPERATURES WILL NOT BE AS WARM AND THEREFORE ANY SNOWMELT WILL BE MINIMAL. ANOTHER ROUND OF RAINFALL IS LIKELY ACROSS THE SOUTHEAST HALF OF THE AREA ON MONDAY...WITH AMOUNTS RANGING FROM A QUARTER TO THREE QUARTERS OF AN INCH. THIS RAIN MIGHT CAUSE ADDITIONAL WITHIN BANKFULL RISES BUT NO FLOODING IS EXPECTED AS THE SNOW IN THIS AREA IS MOSTLY GONE. COLDER DRIER AIR WILL FILTER BACK INTO THE REGION MONDAY NIGHT INTO TUESDAY. ANY ADDITIONAL PRECIPITATION AT THIS POINT WOULD BE SWITCHING TO SNOW...BUT LIGHT AND SPOTTY WITH NO IMPACTS ON RIVERS AND STREAMS. THE COLDER TEMPERATURES WILL ALSO SLOW DOWN ANY LEFTOVER RUNOFF. DRY AND COLD WEATHER EXPECTED THROUGH THE REST OF THE WEEK. 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...HWJIV NEAR TERM...FRUGIS/HWJIV/JPV SHORT TERM...HWJIV LONG TERM...ELH AVIATION...FRUGIS/JPV HYDROLOGY...HWJIV/JPV
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
942 PM CST TUE DEC 24 2013 .DISCUSSION... 810 PM CST MADE SOME ADJUSTMENTS TO HOURLY TEMPERATURES TO ACCOUNT FOR A QUICK FALL THIS EVENING...BUT WITH CLOUD COVER THICKENING AND LOWERING AND WARM AIR ADVECTION STRENGTHENING WOULD ANTICIPATE STEADY OR RISING TEMPS THE REMAINDER OF THE NIGHT. FIRST BATCH OF SNOW OVER EASTERN IOWA LOOKS TO BE TAKING AIM ON MOSTLY WISCONSIN AS VERY DRY AIR (RH AROUND 10% AT 850MB ON 00Z DVN SOUNDING) IS RESULTING IN A BIG VIRGA STORM OVER NORTHERN ILLINOIS AT THIS TIME. GUIDANCE STILL INDICATES THAT INCREASING ASCENT AND CONTINUED MOISTENING FROM TOP DOWN WILL LIKELY RESULT IN SATURATION AND SNOW DEVELOPING LATER THIS EVENING AND PARTICULARLY AFTER MIDNIGHT. LATEST SUITE OF GUIDANCE HAS BEEN INCREASINGLY PESSIMISTIC WITH RESPECT TO QPF AMOUNTS OVER OUR CWA LATER TONIGHT INTO XMAS MORNING. WOULD NOT TAKE MUCH TO SQUEEZE OUT A TENTH OF AN INCH OF SNOWFALL SO ONLY GOING TO SCALE BACK POPS SLIGHTLY OVER CENTRAL AND SOUTHERN PORTIONS OF THE CWA WHILE MAINTAINING CATEGORICAL. REGARDING SNOWFALL TOTALS...LATEST GUIDANCE WOULD SUGGEST THAT EVEN AN INCH WOULD BE UNATTAINABLE WITH THIS SYSTEM EXCEPT FOR FAR NORTHERN COUNTIES. NOT TERRIBLY KEEN ON MAKING BIG CHANGES ON THIS SHIFT...SO GOING TO JUST GENTLY SCALE BACK AMOUNTS A BIT RATHER THAN GO WITH WHAT IS LOOKING TO BE THE MORE LIKELY SCENARIO WHICH IS MOST AREAS GETTING LITTLE MORE THAN A DUSTING THROUGH CHRISTMAS MORNING. SECOND SHORTWAVE PIVOTING AROUND THE POLAR VORTEX STILL LOOKS ON TARGET TO BRING ANOTHER CHANCE OF SNOW SHOWERS LATER TOMORROW AFTERNOON INTO TOMORROW EVENING...AGAIN ESPECIALLY NORTHERN CWA. WILL LET THE NIGHT CREW HANDLE ANY GRID ADJUSTMENTS WITH THAT SYSTEM. IZZI //PREV DISCUSSION... 225 PM CST MAIN FORECAST CONCERNS WILL BE HONING IN ON A PAIR OF DISTURBANCES BRINGING ACCUMULATING SNOW TONIGHT AND AGAIN DURING THE EVENING TOMORROW...AS WELL AS TEMPERATURE TRENDS WITH NON-DIURNAL TEMPS TONIGHT AND BITTER COLD RETURNING EARLY NEXT WEEK. TODAY AND TONIGHT... PAIR OF UPPER LEVEL DISTURBANCES EVIDENT ON WATER VAPOR IMAGERY THIS AFTERNOON...THE FIRST TRANSLATING EAST ACROSS NEBRASKA...WHILE A SECOND WAVE IS DIGGING ACROSS THE CANADIAN PRAIRIES. THE SOUTHERN WAVE IS FORECAST TO LIFT ACROSS NRN IL/SRN WI OVERNIGHT. ISENTROPIC ASCENT INCREASES AHEAD OF THE WAVE LATE THIS EVENING...WITH TOP DOWN SATURATION GRADUALLY EATING AWAY AT THE VERY DRY AIR MASS CURRENTLY IN PLACE. MOST MODELS INDICATE THAT PRECIP WILL BEGIN JUST BEFORE MIDNIGHT OVER NORTH CENTRAL ILLINOIS AND INITIALLY WILL BE MAINLY CONFINED TO THE TIER OR TWO OF COUNTIES NEAR THE STATE LINE WITH DRY AIR WINNING OUT OVER AREAS FARTHER SOUTH. COLD TEMPERATURES WITH A FAIRLY DEEP ISOTHERMAL LAYER THAT EXTEND FROM NEAR THE SURFACE TO ABOUT 6KFT AND COINCIDES NEAR THE BASE OF THE DENDRITIC GROWTH ZONE WILL HELP LEAD TO FLUFFIER THAN AVERAGE SNOW RATIOS...17-20:1 INITIALLY PER COBB OUTPUT. BETTER FORCING ASSOCIATED WITH THE UPPER WAVE WILL BE RIGHT ON THE HEALS OF THIS FIRST WARM ADVECTION BURST OF SNOW AND WILL LEAD TO SNOW SPREADING SOUTHEAST ACROSS THE REMAINDER OF THE CWA...INCLUDING THE CHICAGO METRO AREA BY AROUND 3AM CST. DGZ NOT NEARLY AS DEEP OVER REMAINDER OF CWA WITH SLIGHTLY WARMER TEMPS IN THE LOW/MID LEVELS AND A 2-3KFT DEEP DGZ NEAR THE TOP OF THE SATURATED LAYER BUT COINCIDING WITH THE BETTER LIFT. THIS WILL RESULT IN STILL DRY BUT CLOSER TO AVERAGE RATIOS OF 14-16:1. WITH A BLEND OF NAM/GFS TIMING/QPF THIS EVENING...CONTINUE TO CALL FOR 1-3 INCHES OF SNOW NORTH OF THE I-88 CORRIDOR...1 TO 2 INCHES BETWEEN I-88 AND A PONTIAC TO VALPARAISO LINE...AND UP TO AN INCH SOUTH OF THAT LINE. IN ADDITION TO ACCUMULATING SNOWFALL...PRESSURE GRADIENT WILL TIGHTEN BETWEEN A STRONG DEPARTING HIGH CURRENTLY OVERHEAD AND THE APPROACHING FRONTAL TROUGH. THIS WILL RESULT IN BREEZY CONDITIONS DEVELOPING OVERNIGHT WITH GUSTS INTO THE 20 TO 25 MPH RANGE. GIVEN THE DRY NATURE OF THE SNOW...THIS WILL LIKELY CONTINUE TO BLOW SNOW AROUND AFTER IT FALLS TO THE SURFACE. THE INCREASING SOUTHERLY FLOW WILL ALSO LEAD TO WARMING TEMPERATURES THROUGH THE OVERNIGHT HOURS WITH LOWS HAPPENING THIS EVENING. BY DAYBREAK TOMORROW...EXPECT TEMPERATURES TO WARM INTO THE HIGH TEENS TO LOW 20S. WEDNESDAY THROUGH FRIDAY... AFOREMENTIONED NORTHERN WAVE WILL CONTINUE TO DIG INTO THE MIDWEST...CARVING OUT A TROUGH THAT WILL SHIFT EAST ACROSS THE AREA LATE WEDNESDAY EVENING. MOISTURE WITH THIS SECOND WAVE IS MORE SHALLOW...AND WILL BE LOOKING AT CLOSER TO AVERAGE SNOW RATIOS. QUICK HITTING SYSTEM MAY PRODUCE UP TO AN ADDITIONAL INCH NORTH OF THE I-88 CORRIDOR WITH LITTLE IF ANY SNOW SOUTH. TEMPERATURES WEDNESDAY NIGHT A BIT TRICKY...WITH SOME GUIDANCE POINTING AT MUCH COOLER TEMPS THAN FORECAST...IN FACT SUB ZERO WEST OF THE FOX RIVER VALLEY. HOWEVER...YET ANOTHER VORT LOBE WILL PIVOT ACROSS THE AREA...AND WHILE DO NOT EXPECT ANY APPRECIABLE PRECIP WITH THIS WAVE...IT SHOULD AT LEAST HOLD ONTO CLOUD COVER OVERNIGHT. WITH THE RIDGE AXIS CENTERED OVER IOWA...DOES NOT APPEAR TO FAVOR A STRONG RADIATIONAL COOLING SETUP AND WILL DISMISS THE COLDEST GUIDANCE. RIDGE AXIS WILL ARRIVE OVERHEAD MIDDAY THURSDAY AND SHOULD KEEP CONDITIONS DRY MOST OF THURSDAY AND FRIDAY. THOUGH AS THE SURFACE RIDGE BREAKS DOWN LATER THURSDAY AND FRIDAY...WITH THE AREA UNDER NORTHWEST FLOW WILL HAVE TO KEEP AN EYE ON THE POTENTIAL FOR A EVEN A WEAK UPPER LEVEL DISTURBANCE TO SQUEEZE OUT SOME LIGHT SNOW...AS SUGGESTED BY THE NAM. WILL KEEP "SILENT" 10-14 POPS IN THE MEANTIME. SATURDAY THROUGH TUESDAY... MODELS HAVE BEEN ADVERTISING A RELATIVELY STRONG CLIPPER SYSTEM TO IMPACT PRIMARILY THE NORTHERN LAKES REGION OVER THE WEEKEND WITH SMALL CHANCES FOR SNOW INTO NORTHERN ILLINOIS WITH A STRONG COLD FRONT SWEEPING ACROSS THE AREA. AHEAD OF THE FRONT ON SATURDAY... 7-8C H85 THERMAL RIDGE WILL ADVECT OVERHEAD. EVEN WITH SOME SNOW ON THE GROUND...LOCAL UPPER AIR CLIMATOLOGY SUGGESTS THAT MOST AREAS SHOULD BE ABLE TO GET WELL INTO THE 30S...WITH LOW 40S EVEN A POSSIBILITY...AN IDEA SUPPORTED BY A CONSENSUS MODEL BLEND. A STRONG COLD FRONT WILL SWEEP ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY WITH H85 TEMPS PLUMMETING TO -17 TO -18C BY SUNDAY NIGHT. DEPENDING ON THE EXACT TIMING THE OF THE FRONT...THIS COULD LEAD TO EARLY MORNING LOWS SUNDAY WITH TEMPS FALLING THROUGH THE DAY AND NIGHT...BOTTOMING OUT IN THE LOW SINGLE DIGITS OR EVEN BELOW ZERO ONCE AGAIN...WITH THE COLD AIR MASS LINGERING INTO THE DAY TUESDAY. BACK UNDER NORTHWEST FLOW ALOFT...THERE WILL BE PERIODIC CHANCES FOR LIGHT SNOW EARLY NEXT WEEK. DEUBELBEISS && .AVIATION...UPDATED 03Z... //ORD AND MDW CONCERNS...UPDATED 22Z... * PERIOD OF LIGHT SNOW TONIGHT. * IFR VSBY DURING SHORT PERIODS OF SOMEWHAT INCREASED SNOWFALL RATE. * MVFR CIG PERSISTING THROUGH TONIGHT AND THU. * CHANCE OF ANOTHER PERIOD OF LIGHT SNOW LATE FRI AFTERNOON AND FRI EVENING. //DISCUSSION...UPDATED 00Z... FOCUS IS ON PERIOD OF -SN TO OCCUR LATE TONIGHT INTO EARLY WED MORNING...AND ON POTENTIAL FOR A SECOND PERIOD OF -SN DURING LATE AFTERNOON AND EARLY EVENING WED NIGHT. AN UPPER RIDGE WAS MOVING E...WITH ITS AXIS FROM FROM JAMES BAY SSW TO IL EARLY THIS EVENING...WHILE AN UPPER TROUGH MOVED E TO QUEBEC AND THE NORTHEASTERN CONUS. BEHIND THE UPPER RIDGE CURRENTLY OVER OUR REGION IS ANOTHER UPPER TROUGH MOVING OVER MANITOBA...THE NORTHERN PLAINS...CENTRAL HIGH PLAINS...AND SOUTHERN ROCKIES. THE UPPER PATTERN IS TO CONTINUE TO BE PROGRESSIVE WITH UPPER RIDGE AXIS CONTINUING E TO THE ONTARIO- QUEBEC BORDER...LOWER GREAT LAKES AND UPPER OH VALLEY BY 12Z WED WITH THE UPPER TROUGH TO OUR W MOVING TO WESTERN ONTARIO...THE UPPER MS AND THE MID MO VALLEYS. WITHIN THIS UPPER TROUGH MULTIPLE SHORT WAVES ARE SEEN IN IR AND WATER VAPOR SATELLITE. THE STRONGEST WAS MOVE OVER SOUTHERN MN WITH CLOUD TOPS STARTING TO GET COLDER. WHILE THE MAIN SHORT WAVE TROUGH AND THE ASSOCIATED FORCING IS PROGGED TO MOVE ACROSS WI TO LAKE MI OVERNIGHT...THERE WILL BE AN AREA OF DEEP ISENTROPIC ASCENT SPREADING FROM IA OVER NORTHERN AND E CENTRAL IL DURING THE LATE EVENING AND OVERNIGHT. RADARS SHOWING RETURNS SPREADING INTO N CENTRAL AND E CENTRAL IL BUT METARS BENEATH THE ECHOES NOT REPORTING ANY SN...JUST CLOUDS IN THE 060-120 RANGE AS THE MID LEVEL WARM AIR ADVECTION INCREASES. AS THE LOWER LEVEL FLOW CONTINUES TO INCREASE TONIGHT SO DOES MOISTURE ADVECTION FROM THE SOUTHERN PLAINS NE ACROSS THE OZARKS AND MID MS VALLEY. LATEST MODEL PROGS AVAILABLE AT THIS TIME KEEP THE BULK OF THEIR QPF UP IN WI WITH LIGHT AMOUNTS ACROSS THE LOCAL AREA OVERNIGHT- EARLY MON MORNING. STILL EXPECT A PERIOD OF -SN LOCALLY...WITH A COUPLE HOUR PERIOD OF SOMEWHAT HIGHER SNOWFALL RATES. TOTAL PRECIP AMOUNTS FROM MODELS LIGHT BUT THE SNOW WILL BE OF A FAIRLY HIGH SNOW TO LIQUID RATIO SO STILL MAY SEE SNOWFALL OF 1-2 IN. THE -SN WILL SHOULD QUICKLY END SOON AFTER SUNRISE AS THE SHORT WAVE TROUGH QUICKLY PROGRESSES EASTWARD FROM OVER THE LOCAL AREA. HOWEVER...JUST UPSTREAM OF THE SHORT WAVE TO MOVE OVER US OVERNIGHT IS ANOTHER DISTURBANCE CURRENTLY DROPPING SE OVER ND. THIS SECOND SHORT WAVE TROUGH IS PROGGED MOVE FROM THE MN ARROWHEAD...FAR NW WI...THE UPPER MS VALLEY AND CENTRAL IL TO SW WI...E CENTRAL IA AND FAR W CENTRAL IL DURING THE 25/18Z-26/00Z PERIOD...CONTINUING E ACROSS THE LOCAL AREA WED NIGHT. MOISTURE IS LIMITED WITH THIS DISTURBANCE...ESPECIALLY IN THE MID AND UPPER LEVELS WHERE THE MORE SIGNIFICANT UPWARD MOTION IS TO BE OCCURRING AS THIS NEXT SHORT WAVE TROUGH APPROACHES. BY 026/00Z MODELS SHOWING UVV LOWERING INTO THE TOP PORTION OF THE MOIST LOWER LEVELS. WITH THE COLD AIR THE FAVORED SNOW GROWTH TEMPERATURES ARE ONLY 060-070 AGL SO DO EXPECT ANOTHER SHORT PERIOD OF VERY LIGHT SNOW STARTING POSSIBLY AS EARLY AS LATE WED AFTERNOON...MORE LIKELY THE FIRST HALF OF WED EVENING. LIGHT WINDS WILL BE PICKING UP DURING THE NIGHT OUT OF THE SSE-S AND THEN THE SSW-SW AS SURFACE PRESSURE FALLS OVER WESTERN ONTARIO AND THE UPPER MIDWEST SHIFT TO THE E IN RESPONSE TO THE APPROACH OF THE SHORT WAVE TROUGH. WHILE INCREASING THEY ARE ONLY EXPECTED TO GUST INTO THE 20-25KT RANGE DURING THE OVERNIGHT. THEY SHOULD THEN DIMINISH DURING THE MORNING AS THE TIGHTER SURFACE PRESSURE GRADIENT AND PRESSURE FALLS MOVE OFF TO THE E. TRS //ORD AND MDW CONFIDENCE...UPDATED 03Z... * HIGH IN LIGHT SNOW OCCURRING TONIGHT...AS WELL AS IN GENERAL VSBY TRENDS. * MEDIUM IN TIMING OF SHORT PERIOD OF SLIGHTLY INCREASED SNOWFALL RATE...AND IN END TIME OF ANY ACCUMULATING LIGHT SNOW. * MEDIUM IN MVFR CIGS PERSISTING THROUGHOUT THU. * HIGH IN ANOTHER PERIOD OF LIGHT ACCUMULATING SNOW IN THE AREA LATE AFTERNOON AND EVENING WED...BUT LOW ON IF IT WILL REACH FAR ENOUGH S TO AFFECT IMMEDIATE ORD AND/OR MDW AREAS. TRS //OUTLOOK FOR ORD/MDW FOR 12Z THU-12Z TUE...UPDATED 00Z... THU THROUGH MON...VFR. SLIGHT CHANCE -SN ON SUN AS WELL AS MON NIGHT. && .MARINE... 215 PM CST MAIN CONCERNS FOR THE LAKE ARE GALES DEVELOPING THIS EVENING AND CONTINUE THROUGH WEDNESDAY MORNING. HAZARDOUS WAVES/WINDS WILL ALSO DEVELOP FOR THE NEARSHORE WATERS AND MAY ALSO SEE OCCASIONAL GALE FORCE GUSTS IN THE NEARSHORE WATERS OVERNIGHT THRU DAYBREAK WEDNESDAY. SFC RIDGE OVER THE OHIO VALLEY WILL CONTINUE TO DRIFT EAST TONIGHT...WITH A TIGHTENING GRADIENT ALONG THE WESTERN EDGE. THIS TIGHT GRADIENT WILL SLIDE OVER THE LAKE TONIGHT...PRODUCING SOUTH/SOUTHWEST GALES BETWEEN 35-40KT OVERNIGHT. THE GRADIENT CONTINUES TO SLIDE EAST WITH THE ARRIVAL OF A CLIPPER LOW PRESSURE. THIS CLIPPER WILL ALLOW THE WINDS TO BECOME WESTERLY...AND SHOULD SEE GALES COME TO AN END BY MID-MORNING WED. HOWEVER THE GRADIENT WILL REMAIN RELATIVELY STRONG AND PRODUCE WINDS TO 30KT THRU MIDDAY WED BEFORE DIMINISHING TO 15 TO 25 KT BY WED NIGHT. THE NEXT WEATHER SYSTEM TO BRING A STRONG GRADIENT TO THE LAKE WILL ARRIVE SAT...AND LIKELY PRODUCE WINDS TO 30KT. IT IS POSSIBLE A FEW GUSTS TO GALE FORCE MAY OCCUR SAT. THEN ANOTHER STRONG RIDGE OF HIGH PRESSURE WILL SLIDE SOUTH FROM CENTRAL CANADA FOR THE SECOND HALF OF THE WEEKEND AND MAY BRING A TIGHT GRADIENT TO THE LAKE. BEACHLER && .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 UNTIL 9 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 10 PM WEDNESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
  [top] Area Forecast Discussion National Weather Service Lincoln IL 859 PM CST Tue Dec 24 2013 .DISCUSSION... ISSUED 859 PM CST Tue Dec 24 2013 Plan to update forecast to reduce snow chances tonight and Christmas morning. WAA/isentropic lift ahead of main clipper wave is rapidly shifting east of the area. This forcing has done little more than develop a deck of mid clouds locally. Forcing with the upper wave itself is expected to arrive overnight into the morning hours. There is currently very little snow occurring with the wave right now, at least with the portion of the wave likely to impact central Illinois, and the latest HRRR and 00Z NAM have trended drier. Low temperatures for the night have likely already been attained, with good southerly flow helping temperatures to be steady or slowly rise through the night. This portion and the remainder of the short term forecast is in good shape and only minor tweaks are needed for the latest hourly trends. Bak && .AVIATION... ISSUED 555 PM CST Tue Dec 24 2013 Clipper still on track to cross the Midwest tonight/early Christmas day. Recent model trends suggest the chances for significant snowfall impacting the terminals is diminishing. Following this new thinking, have removed IFR conditions in snow from the terminals. Current plan is for cigs and possibly vsbys to fall to MVFR levels as the clipper passes by after midnight tonight. Still keeping mvfr cigs through the daytime hours Christmas Day, but some models are starting to suggest the cigs will improve to vfr. Bak && .PREV DISCUSSION... ISSUED 250 PM CST Tue Dec 24 2013 Very few changes needed to the forecast as the models remain fairly consistent and in pretty good agreement throughout much of the forecast period. Periodic shots of cold air with no major storms, followed by brief warm-ups will be the main weather trend for the upcoming week. SHORT TERM...Tonight through Thursday High pressure, which brought sub-zero readings to parts of central Illinois this morning, was centered in southwest IN early this afternoon. A southerly wind flow has already developed in Illinois, and this will continue to increase through the evening and overnight. The result will be slowly rising temperatures through the night and into Christmas morning. A clipper system in the northern Plains and its associated weak surface low in north central Nebraska will shift to the ESE tonight, spreading light snow into west central IL mainly after midnight. The axis of the light snow will shift east of the I-55 corridor around daybreak, with lingering flurries to the west. By late morning the snow should come to an end in much of east central Illinois, with some lingering flurries from PIA-DEC-MTO- Robinson. Most areas can expect around 0.5" or less of snow, except in locations from Canton to just north of Bloomington where 1.0 to 1.5 inches are likely. The snow should be rather fluffy and will blow around quite a bit with a southwest wind of 10 to 15 mph. Partial clearing is then expected in the wake of the clipper system with temperatures in the lower to middle 30s. Another clipper system will follow on the heels of the first one later on Christmas Day, but the measurable snow should stay well north of central IL. This system will bring central Illinois a glancing blow of colder air, so highs on Thursday will be a bit cooler along and north of I-74. The rest of central and SE IL can expect highs Thursday to be very similar to Wednesday`s. LONG TERM...Friday through Tuesday Overall, the medium and long range models are in pretty good agreement with the mean upper level flow from the weekend into early next week. By Friday, the upper level trough axis in the eastern U.S. will breakdown and become flatter/more westerly. This will allow temperatures to warm slightly Friday, with a nice warm- up well into the 40s expected Saturday. Locations north of I-74, however, may have some lingering snow which could keep temperatures down in the upper 30s. Both the GFS and European agree that the main longwave trough will re-establish itself in the eastern U.S. by early next week. However, they arrive at the solution differently - particularly Sunday into Monday. The GFS is weaker with the trough early on, and redevelops the longwave gradually. The European is stronger and sharper with the shortwaves that carve out the new trough, which results in a solution of light snow Sunday in the upper Midwest and northern IL. Low level moisture will be quite low, and due to the lack of persistence in the European model with this scenario will hold of on mentionable PoPs for now, and keep the forecast in the slight chance category. Both models do agree, however, that another shot of very cold air is in store for the Midwest by late Sunday and lasting into New Year`s Eve with lows in the single digits to lower teens, and highs in the teens to lower 20s. Miller && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
319 AM CST MON DEC 23 2013 .DISCUSSION... 745 PM CST MINOR CHANGES MADE TO THE TONIGHT/S FORECAST....FOR FLURRIES/LIGHT SNOW TRENDS THIS EVENING AND TO OVERNIGHT LOWS. THE LATEST SHORT WAVE TROUGH TO AFFECT THE AREA WAS OVER SW WI AND NE IA EARLY THIS EVENING AND IS PROGGED TO MOVE ACROSS THE LOCAL AREA DURING THE LATER EVENING AND FIRST PART OF THE OVERNIGHT HOURS. THIS DISTURBANCE HAS BEEN PRODUCING LIGHT SNOW AND FLURRIES WHICH HAVE SPREAD FROM N CENTRAL TO NE IL OVER THE LAST FEW HRS. VISIBILITY HAD BEEN REDUCED TO 2 1/2 TO 4 MI OVER PORTIONS OF SOUTHERN WI BUT MINIMAL IF ANY REDUCTION IN VISIBILITY REPORTED S OF THE STATE LINE. FLURRIES ARE EXPECTED ACROSS MUCH OF THE FORECAST AREA THIS EVENING WHILE THE POTENTIAL FOR LIGHT SNOW OF ANY CONSEQUENCE N OF I-80 AND INCREASING AS ONE GETS CLOSER TO THE WI STATE LINE. EVEN THEN AMOUNTS OF NEW SNOWFALL WILL BE A 1/2 INCH OR LESS...GENERALLY ONLY A TENTH OR TWO. REGARDING OVERNIGHT LOWS...AT 01Z TEMPERATURES QUICKLY DROPPED OFF FROM AROUND 20 ALONG THE MS RIVER TO SINGLE DIGITS IN N CENTRAL IA AND SW MN. SOME OF THIS IS DUE TO CLEARING OF THE LOWER CLOUDS FROM OVER PARTS OF THAT AREA BUT EVEN DURING THE AFTERNOON TEMPERATURES WERE ONLY IN THE 7 TO 14 DEG RANGE. LATEST PROGS OF SFC...BL AND OTHER LOW LEVEL TEMPS SHOW THIS COLD AIR ADVECTING E SLIGHTLY DEEPER OVER THE W PORTION OF THE FORECAST AREA BY SUNRISE. THUS...HAVE SHAVED MAYBE A DEG OR SO OFF OF LOWS ACROSS THE FAR WESTERN COUNTIES. //PREV DISCUSSION... 326 PM CST AS THE LATEST BOUT OF WINTER WEATHER WINDS DOWN...THE MAIN FOCUS FOR THE NEXT SEVERAL DAYS WILL BE THE TEMPERATURE TRENDS. HOWEVER...FOR THE REMAINDER OF THE AFTERNOON AND THROUGH THE OVERNIGHT HOURS...THE CHANCES FOR PCPN ARE NOT TOTALLY OVER. THIS AFTERNOON...A MID LEVEL DRY SLOT HAS CAPPED THE DEEP LAYER MOISTURE FROM THE TOP WHILE COLD...DRY ADVECTION HAS DECREASED MOISTURE AT THE SURFACE. THIS HAS LEFT A SHALLOW ZONE OF SATURATION THAT WILL NOT BE DEEP ENOUGH INTO THE COLD AIR ALOFT TO GENERATE ANY ICE PRODUCTION...LIMITING THE PCPN POTENTIAL TO DRIZZLE. AT THE SURFACE...THE DRY ADVECTION HAS DECREASED DEWPOINTS ENOUGH THAT ANY DRIZZLE THAT FALLS FROM THE SHALLOW CLOUD DECK WILL NOT REACH THE GROUND. SO...WITH TEMPERATURES DROPPING BELOW FREEZING THROUGH THE AFTERNOON WITH THE PERSISTENT COLD ADVECTION AT THE SURFACE...THE POTENTIAL FOR ANY FREEZING DRIZZLE IS MINIMAL. THE OTHER OF ADDITIONAL PCPN WILL COME THIS EVENING AND OVERNIGHT AS A NRN STREAM SHORTWAVE DROPPING OUT OF THE NORTHERN PLAINS REINFORCES A SECONDARY COLD FRONT DROPPING SOUTH THROUGH WISCONSIN. WITH DEEP LAYER MOISTURE ON A DECREASING TREND AS THE STRONG SOUTHERN STREAM SYSTEM MOVES OFF TO THE EAST...THE ENHANCED DYNAMICS FROM THE SHORTWAVE AND SFC CONVERGENCE FROM THE COLD FRONT WILL ONLY BE SUFFICIENT TO GENERATE A LITTLE LIGHT SNOW...WITH MINOR ADDITIONAL ACCUMULATIONS...GENERALLY AROUND A COUPLE TENTHS OF AN INCH... ESPECIALLY FOR THE NORTHERN PORTIONS OF THE CWA. THE SOUTHERN PORTIONS OF THE CWA SHOULD SEE LITTLE OR NO ACCUMULATION. THROUGH THE DAY TOMORROW...THE MAIN LONGWAVE UPPER TROUGH WILL MOVE THROUGH THE MIDWEST AND WESTERN GREAT LAKES REGIONS...KEEPING A CHANCE FOR SOME FLURRIES POSSIBLE THROUGH MUCH OF THE DAY TOMORROW. AS THE UPPER TROUGH MOVES ACROSS THE AREA...COLD ARCTIC HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS AND INTO THE MIDDLE MISSISSIPPI VALLEY. THIS WILL BE THE FIRST IN A SERIES OF ARCTIC AIR INTRUSIONS INTO THE REGION. BY MONDAY MORNING...TEMPERATURES SHOULD DROP INTO THE SINGLE DIGITS WEST OF THE I-39 CORRIDOR WITH THE SLIGHTLY WARMER AIR HANGING IN TO THE EAST. UNDER A PERSISTENT FETCH OF ARCTIC AIR...THERE WILL BE LITTLE DIURNAL WARMING THROUGH THE DAY ON MONDAY WITH HIGHS TOPPING OUT AT 10-15F WEST OF THE FOX VALLEY AND I-55 CORRIDOR WHILE TO THE EAST...TEMPERATURES REMAIN STEADY THROUGH THE DAY IN THE LOW 20S. INTO TUESDAY MORNING...AS SFC HIGH PRESSURE BUILDS ACROSS THE MISSISSIPPI VALLEY WITH THE CENTER OF THE HIGH MOVING THROUGH SOUTHERN IL...TEMPERATURES WILL DROP BELOW ZERO ALONG AND WEST OF A WAUKEGAN TO PONTIAC LINE...INCLUDING THE ROCKFORD METRO AREA...WHILE TEMPS TO THE EAST OF THIS LINE WILL DROP INTO THE LOWER SINGLE DIGITS...INCLUDING THE CHICAGO METRO AREA. WEST WINDS OF 5 TO 10 MPH WILL BE SUFFICIENT TO CAUSE DANGEROUSLY COLD WIND CHILL READING WITH THE ROCKFORD TO PONTIAC AREA POSSIBLE REACHING WIND CHILL ADVISORY LEVELS OF -20F TO -25F. THE REST OF TUESDAY WILL REMAIN QUITE COLD FOR LAST MINUTE CHRISTMAS SHOPPING AS HIGHS WILL RANGE FROM THE SINGLE DIGITS OVER THE ROCKFORD AREA TO THE LOWER TO MIDDLE TEENS OVER THE CHICAGO METRO AREA AND NORTHWESTERN INDIANA. FOR THE NEXT SEVERAL DAYS...THE LONG WAVE UPPER LEVEL PATTERN WILL REMAIN VERY HIGH AMPLITUDE AND PROGRESSIVE. THIS PATTERN WILL LEAD TO RAPIDLY SWINGING PERIODS OF RELATIVE WARMING AND DRASTIC COOLING. FOR CHRISTMAS EVEN INTO CHRISTMAS DAY...A STRONG SHORTWAVE DROPPING OUT OF THE NORTHERN PLAINS WILL BRING ANOTHER CHANCE FOR SOME LIGHT SNOW TO THE REGION. THIS WILL BE THE FIRST IN A SERIES OF CLIPPER-TYPE SYSTEMS SOURCED FROM THE ARCTIC REGION. THESE CLIPPER TYPE SYSTEMS...INCLUDING THE ONE EXPECTED TO IMPACT THE REGION FOR CHRISTMAS EVE AND THROUGH CHRISTMAS DAY TYPICALLY HAVE LITTLE DEEP LAYER MOISTURE TO WORK WITH AND THUS RELY ON UPPER DYNAMICS TO GENERATE SNOWFALL. THIS SYSTEM WILL BE A FAIRLY TYPICAL CLIPPER AND THE REGION COULD BRING PERHAPS 1 TO 2 INCHES. FOLLOWING A PERIOD OF RELATIVE "WARMTH" ON WEDNESDAY WITH HIGHS IN THE MIDDLE TO UPPER 20S OVER THE NORTHERN PORTIONS OF THE CWA TO THE LOW 30S OVER THE SOUTHERN LOCATIONS...ANOTHER SHOT OF ARCTIC AIR WILL MOVE IN WEDNESDAY NIGHT THROUGH FRIDAY. THE COLDEST PERIOD WILL BE FRIDAY MORNING WHEN...ONCE AGAIN...THE NORTHWESTERN HALF OF THE CWA WILL SEE TEMPERATURES DROP TO -5F TO -10F...WHILE THE SERN PORTION OF THE CWA ONLY DROPS TO THE LOWER SINGLE DIGITS. THE MODELS HAVE BEEN VERY CONSISTENT WITH THE PATTERN THROUGH THE WEEK AND THE HIGH PRESSURE CENTER ASSOCIATED WITH THIS ARCTIC AIRMASS WILL MOVE THROUGH SRN WISCONSIN AND NORTHERN ILLINOIS. SO...WHILE AIR TEMPERATURES WILL BE SIMILAR TO THOSE SEEN ON TUESDAY MORNING...WIND CHILLS WILL NOT BE QUITE AS LOW AS WINDS SHOULD NOT BE QUITE AS STRONG. HOWEVER...THERE IS STILL SOME BUST POTENTIAL FOR MIN TEMPS FRIDAY MORNING IF WINDS GO CALM RATHER THAN REMAINING AROUND 5MPH. THE LIGHT WIND WOULD BE JUST ENOUGH TO TO KEEP THE SFC STIRRED UP...LIMITING COOLING. ON THE OTHER HAND...IF THE SFC WINDS CAN MANAGE TO GO CALM...AND SKIES CLEAR OUT ENOUGH...ENHANCED RADIATIONAL COOLING AIDED BY SOME RESIDUAL SNOW COVER COULD ALLOW TEMPERATURES TO DROP EVEN LOWER THAN CURRENTLY ANTICIPATED. FOR THE WEEKEND AND INTO EARLY NEXT WEEK...WITH THE PATTERN REMAINING QUICKLY PROGRESSIVE...TEMPERATURES FOR THE WEEKEND SHOULD REBOUND BACK CLOSER TO SEASONAL NORMAL LEVELS. HIGHS SHOULD BE IN THE UPPER 20S TO LOWER 30S. THE LONG RANGE MODEL GUIDANCE IS INDICATING THE CHANCE FOR ANOTHER SHOT OF ARCTIC AIR WITH SUB-ZERO TEMPERATES BY MONDAY MORNING. THE LONG RANGE FORECAST PERIOD SHOULD BE DRY WITH THE NEXT CHANCE FOR ANY PCPN COMING EARLY NEXT WEEK AS THE NEXT CLIPPER MOVES THROUGH THE AREA. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * VARIABLE MVFR CIGS THROUGH THE MORNING WITH SOME BREAKS TO VFR POSSIBLE AT TIMES. VFR SCATTERING/CLEARING MAY RETURN BY MIDDAY...WITH MVFR RETURNING LATER IN THE AFTERNOON. * LIGHT SNOW WITH BRIEF MVFR VSBY DEPARTING NEXT HOUR OR SO LEAVING FLURRIES BEHIND. * LIGHT SNOW/FLURRIES RETURN LATER THIS AFTERNOON AND THIS EVENING. MDB //DISCUSSION...UPDATED 09Z... BAND OF LIGHT SNOW WITH SOME MVFR VSBY CONTINUES TO WORK EAST ACROSS THE CHI METRO TERMINALS INTO NW INDIANA. EXPECT THIS TO CLEAR THE AREA IN THE NEXT FEW HOURS LEAVING SOME FLURRIES BEHIND. VARIABLE MVFR CIGS...WITH SOME BREAKS TO VFR STILL SCATTERED ABOUT...WILL CONTINUE THROUGH MUCH OF THE MORNING BUT AM WATCHING THE EASTWARD ADVANCEMENT OF CLEARING TOWARD THE MISSISSIPPI RIVER. THIS MAY BE ABLE TO WORK INTO THE TERMINALS LATE THIS MORNING SO MAY NEED TO SCATTER CLOUDS OUT BY MIDDAY. DO EXPECT MVFR TO RETURN LATER THIS AFTERNOON AS LIGHT SNOW CHANCES INCREASE. MDB FROM 06Z... AN UPPER TROUGH MOVING ACROSS THE AREA CONTINUES TO GENERATE SOME LIGHT SNOW ACROSS THE TERMINALS WHICH WILL BE EXITING IN THE NEXT FEW HOURS. CIGS ARE QUITE VARIABLE BUT MAINLY MVFR THOUGH THERE IS AN AREA OF VFR CIGS FROM THE CHICAGO METRO EASTWARD OVER LAKE MICHIGAN INTO THE GYY AREA. THIS LOOKS TO BE SHORT LIVED WITH MORE MVFR UPSTREAM WORKING ITS WAY TOWARD THIS AREA OF IMPROVEMENT. EXPECT VARIABLE MVFR CIGS THROUGH THIS AFTERNOON AND PROBABLY THE UPCOMING EVENING AS WELL. CANNOT RULE OUT ADDITIONAL VFR BREAKS THROUGH THE DAY THOUGH. ANOTHER TROUGH WILL BRING LIGHT SNOW AND FLURRIES TO THE TERMINALS THIS AFTERNOON INTO THIS EVENING. THIS LOOKS TO BE LIGHT OVERALL BUT SOME MINIMAL VSBY REDUCTION IS POSSIBLE AT TIMES SO WILL NEED TO MONITOR INTENSITY TRENDS LATER TODAY. WINDS WILL REMAIN WESTERLY THROUGH THE PERIOD WITH PERIODIC 15 TO 20 KT GUSTS DEVELOPING LATER THIS MORNING. MDB //ORD AND MDW CONFIDENCE...UPDATED 09Z... * HIGH CONFIDENCE IN VARIABLE MVFR CIGS THROUGH THE MORNING...MEDIUM CONFIDENCE IN VFR SCATTERING POTENTIAL TOWARD MIDDAY. MEDIUM CONFIDENCE IN MVFR RETURNING LATER THIS AFTERNOON. * HIGH CONFIDENCE IN VSBY REDUCING LIGHT SNOW DEPARTING NEXT HOUR OR SO WITH FLURRIES CONTINUING. * MEDIUM CONFIDENCE IN ADDITIONAL LIGHT SNOW/FLURRIES LATER THIS AFTERNOON WITH LOW CONFIDENCE IN CIG/VSBY IMPACTS. MDB //OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z... TUESDAY...VFR DURING THE DAY. CHANCE OF LIGHT SNOW LATER TUESDAY NIGHT WITH MVFR/IFR POSSIBLE. WEDNESDAY...CHANCE OF LIGHT SNOW EARLY. MVFR/IFR POSSIBLE. THURSDAY...VFR. FRIDAY...VFR. SATURDAY...VFR. RATZER && .MARINE... 302 AM CST THE MAIN PERIOD OF CONCERN REMAINS THE TUESDAY NIGHT-WEDNESDAY TIME FRAME WITH THE POTENTIAL FOR GALES CONTINUING. LOW PRESSURE IS MOVING EASTWARD ACROSS NEW ENGLAND AND WILL MOVE OFFSHORE LATER ON TODAY. STRONG HIGH PRESSURE IS MOVING SOUTHWARD INTO THE DAKOTAS AND WILL REACH THE LOWER OHIO VALLEY BY TUESDAY AFTERNOON...WITH A RIDGE AXIS EXTENDING NORTHWARD ACROSS LAKE MICHIGAN AT THAT TIME. NORTHERLY WINDS ACROSS NORTHERN SECTIONS OF THE LAKE TURN WESTERLY ACROSS THE SOUTHERN PART OF THE LAKE...WITH STRONGER SPEEDS ACROSS THE FAR SOUTHERN QUARTER OR SO OF THE LAKE. THIS IS DUE TO A LINGERING FAIRLY STRONG PRESSURE GRADIENT WHICH WILL GRADUALLY WORK AWAY FROM THE AREA TONIGHT. WILL NEED TO KEEP AN EYE ON WINDS ACROSS THE INDIANA NEARSHORE WATERS AS THEY MAY BE CLOSE TO SMALL CRAFT ADVISORY CRITERIA BUT RIGHT NOW EXPECT THEM TO REMAIN JUST BELOW. ONCE THE RIDGE CRESTS THE LAKE TUESDAY AFTERNOON WINDS WILL QUICKLY TURN SOUTHERLY AND INCREASE IN SPEED AS A LOW PRESSURE TROUGH WORKS IN FROM THE WEST. WITH A COLD ATMOSPHERE IN PLACE UNSTABLE CONDITIONS WILL CONTINUE ACROSS THE LAKE DESPITE WARM ADVECTION ALOFT AS THE PRESSURE GRADIENT BETWEEN THE TWO SYSTEMS STRENGTHENS. THE SIGNAL FOR GALES REMAINS CONSISTENT ACROSS MUCH OF THE LAKE FROM TUESDAY EVENING THROUGH MID OR LATE WEDNESDAY MORNING. THE STRONGEST SPEEDS WILL BE CENTRAL AND NORTH AND COULD SEE SOME GUSTS OVER 40 KT BASED ON CURRENT INDICATIONS. WILL GO AHEAD AND BUMP WINDS TO 40 KT ACROSS THE CENTRAL AND NORTHERN PARTS OF THE LAKE DURING THIS TIME. WILL ALSO GO AHEAD AND ISSUE A GALE WATCH FOR THIS TIME AS WELL GIVEN THAT THE SIGNAL HAS BEEN CONSISTENT FOR SEVERAL DAYS NOW. WILL LEAVE THE NEARSHORE WATERS OUT OF THE WATCH FOR NOW WITH SOME UNCERTAINTY IN GALES REACHING THAT FAR SOUTH AND A MAINLY OFFSHORE COMPONENT...BUT WINDS MAY BE DUE SOUTH FOR A TIME TUESDAY EVENING BRINGING GALES TO THE ILLINOIS WATERS THANKS TO THE MORE SHORE PARALLEL DIRECTION. WINDS WILL TURN SOUTHWEST THEN WEST STARTING WEDNESDAY MORNING WITH SPEEDS EASING UP AS THE PRESSURE GRADIENT SLACKENS. HIGH PRESSURE WILL BUILD BACK ACROSS THE LAKE THURSDAY BUT QUICKLY DEPART TO THE EAST WITH SEVERAL LOW PRESSURE SYSTEMS CROSSING THE REGION FRIDAY AND SATURDAY. THESE WILL ALLOW WINDS TO FLUCTUATE BETWEEN NORTHWEST AND SOUTHWEST AS THEY PASS AS WELL AS ALLOW SPEEDS TO INCREASE. A LITTLE EARLY FOR DETAILS BUT IT DOES APPEAR THAT A BETTER ORGANIZED LOW WILL PASS TO THE NORTH SOME TIME SATURDAY WITH ANOTHER STRONG HIGH BUILDING IN BEHIND IT. THIS WOULD HAVE THE BEST POTENTIAL TO BRING A PERIOD OF GALES AT SOME POINT SATURDAY INTO SUNDAY...WITH PERHAPS THE BETTER POTENTIAL EARLY SUNDAY AS THE LOW PASSES AND THE HIGH APPROACHES. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 PM TUESDAY TO NOON WEDNESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 245 AM CST Mon Dec 23 2013 .DISCUSSION... ISSUED 245 AM CST Mon Dec 23 2013 SHORT TERM...Today through Wednesday Ridge of high pressure currently over the Plains will build eastward today, allowing skies to partially clear across central Illinois. 08z/2am IR satellite imagery shows back edge of low clouds along a Galesburg to Quincy line, with timing tools taking the clearing line to near the I-55 corridor by mid-morning. After a period of mostly sunny skies across the western KILX CWA this morning, think diurnal clouds will re-develop thanks to cyclonic flow aloft. End result will be partly sunny skies west and mostly cloudy conditions further east toward the Indiana border. Given strong CAA, temps will struggle to rise much from early morning lows, with afternoon highs ranging from the teens along/west of I-55 to around 30 degrees south of I-70. Skies will clear out completely tonight, setting up one of the coldest nights of the winter season thus far. Overnight lows will drop into the single digits across the board, with readings dipping below zero in the Illinois River Valley. Coldest temps of around -8F will be found in the far NW CWA around Galesburg where 4 inches of snow remain on the ground. W/NW winds of 10 to 15 mph in the evening will subside to less than 10 mph overnight, producing bitterly cold wind-chill values. Will be issuing a Wind Chill Advisory for locations along and north of a Rushville to Bloomington-Normal line, where wind-chills will plunge into the -15 to -20F range tonight into Tuesday morning. After a very cold day on Tuesday with highs only in the teens and 20s, winds will switch to southerly and temps will warm considerably ahead of an approaching clipper system Tuesday night into Wednesday. Models agree that system is a bit faster than previously forecast, but still disagree on how far south to spread QPF. Prefer the NAM model, which brings light snow across much of central Illinois late Tuesday night into Wednesday morning. Greatest chance for measurable snow still looks to be focused from the Peoria area northward, where likely POPs are in order. Snow chances decrease further south, with only slight chance POPs along/south of I-70. Even though system will be fast-moving and will depart the area around midday Wednesday, think around one half inch of snow will be possible across the far northern CWA by Wednesday morning. Any new snow that falls will likely not stick around for long though, as high temps reach the 30s on Wednesday. LONG TERM...Thursday through Sunday Yet another wave will dig southward Wednesday night, bringing a few snow flurries to the area. Once this feature passes, another chunk of very cold air will settle southward into central Illinois by the end of the week, resulting in high temps only in the 20s on Thursday and Friday. The temperature roller-coaster ride will continue next weekend, as another fast-moving storm system approaches from the northwest. Southerly winds ahead of this feature will boost temps back into the 30s on Saturday, before another shot of very cold air arrives early next week. Barnes && .AVIATION... ISSUED 1110 PM CST Sun Dec 22 2013 Main forecast challenge will be with any appreciable clearing of the MVFR cigs across the area towards morning. Latest satellite data and surface obs showing the backedge of the cloud shield was still over east central Iowa late this evening, and tracking southeast at about 20 kts. This would put any clearing into PIA and SPI between 10z and 12z and to the east of CMI by 15z. Not very confident on that scenario, despite most models trending in that direction. HRRR has been the quickest with the backedge of the cloud shield progressing across our forecast area in the 06z-09z time frame, while the Nam-Wrf and local Wrf-ARW models were a bit more conservative in the clearing trend from west to east which we will go with during this forecast period. Still appears the 10z-12z time frame looks ok for PIA and SPI but the hi-res forecast soundings indicate the clouds will tend to slow down their eastward progression tomorrow morning just east of the I-55 corridor with additional stratocu clouds from the north possibly affecting our PIA and BMI TAF sites tomorrow afternoon. We should see any lingering MVFR/low VFR cigs dissipate by tomorrow evening across the north as Arctic high pressure settles in bringing in some very cold temperatures for tomorrow night. Surface winds will remain out of the west to northwest at 10 to 15 kts tonight...with speeds of from 12 to 17 kts on Monday with a few gusts at or above 20 kts at times tomorrow afternoon. Winds should diminish to around 10 kts from the northwest tomorrow evening. Smith && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1211 AM CST MON DEC 23 2013 .DISCUSSION... 745 PM CST MINOR CHANGES MADE TO THE TONIGHT/S FORECAST....FOR FLURRIES/LIGHT SNOW TRENDS THIS EVENING AND TO OVERNIGHT LOWS. THE LATEST SHORT WAVE TROUGH TO AFFECT THE AREA WAS OVER SW WI AND NE IA EARLY THIS EVENING AND IS PROGGED TO MOVE ACROSS THE LOCAL AREA DURING THE LATER EVENING AND FIRST PART OF THE OVERNIGHT HOURS. THIS DISTURBANCE HAS BEEN PRODUCING LIGHT SNOW AND FLURRIES WHICH HAVE SPREAD FROM N CENTRAL TO NE IL OVER THE LAST FEW HRS. VISIBILITY HAD BEEN REDUCED TO 2 1/2 TO 4 MI OVER PORTIONS OF SOUTHERN WI BUT MINIMAL IF ANY REDUCTION IN VISIBILITY REPORTED S OF THE STATE LINE. FLURRIES ARE EXPECTED ACROSS MUCH OF THE FORECAST AREA THIS EVENING WHILE THE POTENTIAL FOR LIGHT SNOW OF ANY CONSEQUENCE N OF I-80 AND INCREASING AS ONE GETS CLOSER TO THE WI STATE LINE. EVEN THEN AMOUNTS OF NEW SNOWFALL WILL BE A 1/2 INCH OR LESS...GENERALLY ONLY A TENTH OR TWO. REGARDING OVERNIGHT LOWS...AT 01Z TEMPERATURES QUICKLY DROPPED OFF FROM AROUND 20 ALONG THE MS RIVER TO SINGLE DIGITS IN N CENTRAL IA AND SW MN. SOME OF THIS IS DUE TO CLEARING OF THE LOWER CLOUDS FROM OVER PARTS OF THAT AREA BUT EVEN DURING THE AFTERNOON TEMPERATURES WERE ONLY IN THE 7 TO 14 DEG RANGE. LATEST PROGS OF SFC...BL AND OTHER LOW LEVEL TEMPS SHOW THIS COLD AIR ADVECTING E SLIGHTLY DEEPER OVER THE W PORTION OF THE FORECAST AREA BY SUNRISE. THUS...HAVE SHAVED MAYBE A DEG OR SO OFF OF LOWS ACROSS THE FAR WESTERN COUNTIES. //PREV DISCUSSION... 326 PM CST AS THE LATEST BOUT OF WINTER WEATHER WINDS DOWN...THE MAIN FOCUS FOR THE NEXT SEVERAL DAYS WILL BE THE TEMPERATURE TRENDS. HOWEVER...FOR THE REMAINDER OF THE AFTERNOON AND THROUGH THE OVERNIGHT HOURS...THE CHANCES FOR PCPN ARE NOT TOTALLY OVER. THIS AFTERNOON...A MID LEVEL DRY SLOT HAS CAPPED THE DEEP LAYER MOISTURE FROM THE TOP WHILE COLD...DRY ADVECTION HAS DECREASED MOISTURE AT THE SURFACE. THIS HAS LEFT A SHALLOW ZONE OF SATURATION THAT WILL NOT BE DEEP ENOUGH INTO THE COLD AIR ALOFT TO GENERATE ANY ICE PRODUCTION...LIMITING THE PCPN POTENTIAL TO DRIZZLE. AT THE SURFACE...THE DRY ADVECTION HAS DECREASED DEWPOINTS ENOUGH THAT ANY DRIZZLE THAT FALLS FROM THE SHALLOW CLOUD DECK WILL NOT REACH THE GROUND. SO...WITH TEMPERATURES DROPPING BELOW FREEZING THROUGH THE AFTERNOON WITH THE PERSISTENT COLD ADVECTION AT THE SURFACE...THE POTENTIAL FOR ANY FREEZING DRIZZLE IS MINIMAL. THE OTHER OF ADDITIONAL PCPN WILL COME THIS EVENING AND OVERNIGHT AS A NRN STREAM SHORTWAVE DROPPING OUT OF THE NORTHERN PLAINS REINFORCES A SECONDARY COLD FRONT DROPPING SOUTH THROUGH WISCONSIN. WITH DEEP LAYER MOISTURE ON A DECREASING TREND AS THE STRONG SOUTHERN STREAM SYSTEM MOVES OFF TO THE EAST...THE ENHANCED DYNAMICS FROM THE SHORTWAVE AND SFC CONVERGENCE FROM THE COLD FRONT WILL ONLY BE SUFFICIENT TO GENERATE A LITTLE LIGHT SNOW...WITH MINOR ADDITIONAL ACCUMULATIONS...GENERALLY AROUND A COUPLE TENTHS OF AN INCH... ESPECIALLY FOR THE NORTHERN PORTIONS OF THE CWA. THE SOUTHERN PORTIONS OF THE CWA SHOULD SEE LITTLE OR NO ACCUMULATION. THROUGH THE DAY TOMORROW...THE MAIN LONGWAVE UPPER TROUGH WILL MOVE THROUGH THE MIDWEST AND WESTERN GREAT LAKES REGIONS...KEEPING A CHANCE FOR SOME FLURRIES POSSIBLE THROUGH MUCH OF THE DAY TOMORROW. AS THE UPPER TROUGH MOVES ACROSS THE AREA...COLD ARCTIC HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS AND INTO THE MIDDLE MISSISSIPPI VALLEY. THIS WILL BE THE FIRST IN A SERIES OF ARCTIC AIR INTRUSIONS INTO THE REGION. BY MONDAY MORNING...TEMPERATURES SHOULD DROP INTO THE SINGLE DIGITS WEST OF THE I-39 CORRIDOR WITH THE SLIGHTLY WARMER AIR HANGING IN TO THE EAST. UNDER A PERSISTENT FETCH OF ARCTIC AIR...THERE WILL BE LITTLE DIURNAL WARMING THROUGH THE DAY ON MONDAY WITH HIGHS TOPPING OUT AT 10-15F WEST OF THE FOX VALLEY AND I-55 CORRIDOR WHILE TO THE EAST...TEMPERATURES REMAIN STEADY THROUGH THE DAY IN THE LOW 20S. INTO TUESDAY MORNING...AS SFC HIGH PRESSURE BUILDS ACROSS THE MISSISSIPPI VALLEY WITH THE CENTER OF THE HIGH MOVING THROUGH SOUTHERN IL...TEMPERATURES WILL DROP BELOW ZERO ALONG AND WEST OF A WAUKEGAN TO PONTIAC LINE...INCLUDING THE ROCKFORD METRO AREA...WHILE TEMPS TO THE EAST OF THIS LINE WILL DROP INTO THE LOWER SINGLE DIGITS...INCLUDING THE CHICAGO METRO AREA. WEST WINDS OF 5 TO 10 MPH WILL BE SUFFICIENT TO CAUSE DANGEROUSLY COLD WIND CHILL READING WITH THE ROCKFORD TO PONTIAC AREA POSSIBLE REACHING WIND CHILL ADVISORY LEVELS OF -20F TO -25F. THE REST OF TUESDAY WILL REMAIN QUITE COLD FOR LAST MINUTE CHRISTMAS SHOPPING AS HIGHS WILL RANGE FROM THE SINGLE DIGITS OVER THE ROCKFORD AREA TO THE LOWER TO MIDDLE TEENS OVER THE CHICAGO METRO AREA AND NORTHWESTERN INDIANA. FOR THE NEXT SEVERAL DAYS...THE LONG WAVE UPPER LEVEL PATTERN WILL REMAIN VERY HIGH AMPLITUDE AND PROGRESSIVE. THIS PATTERN WILL LEAD TO RAPIDLY SWINGING PERIODS OF RELATIVE WARMING AND DRASTIC COOLING. FOR CHRISTMAS EVEN INTO CHRISTMAS DAY...A STRONG SHORTWAVE DROPPING OUT OF THE NORTHERN PLAINS WILL BRING ANOTHER CHANCE FOR SOME LIGHT SNOW TO THE REGION. THIS WILL BE THE FIRST IN A SERIES OF CLIPPER-TYPE SYSTEMS SOURCED FROM THE ARCTIC REGION. THESE CLIPPER TYPE SYSTEMS...INCLUDING THE ONE EXPECTED TO IMPACT THE REGION FOR CHRISTMAS EVE AND THROUGH CHRISTMAS DAY TYPICALLY HAVE LITTLE DEEP LAYER MOISTURE TO WORK WITH AND THUS RELY ON UPPER DYNAMICS TO GENERATE SNOWFALL. THIS SYSTEM WILL BE A FAIRLY TYPICAL CLIPPER AND THE REGION COULD BRING PERHAPS 1 TO 2 INCHES. FOLLOWING A PERIOD OF RELATIVE "WARMTH" ON WEDNESDAY WITH HIGHS IN THE MIDDLE TO UPPER 20S OVER THE NORTHERN PORTIONS OF THE CWA TO THE LOW 30S OVER THE SOUTHERN LOCATIONS...ANOTHER SHOT OF ARCTIC AIR WILL MOVE IN WEDNESDAY NIGHT THROUGH FRIDAY. THE COLDEST PERIOD WILL BE FRIDAY MORNING WHEN...ONCE AGAIN...THE NORTHWESTERN HALF OF THE CWA WILL SEE TEMPERATURES DROP TO -5F TO -10F...WHILE THE SERN PORTION OF THE CWA ONLY DROPS TO THE LOWER SINGLE DIGITS. THE MODELS HAVE BEEN VERY CONSISTENT WITH THE PATTERN THROUGH THE WEEK AND THE HIGH PRESSURE CENTER ASSOCIATED WITH THIS ARCTIC AIRMASS WILL MOVE THROUGH SRN WISCONSIN AND NORTHERN ILLINOIS. SO...WHILE AIR TEMPERATURES WILL BE SIMILAR TO THOSE SEEN ON TUESDAY MORNING...WIND CHILLS WILL NOT BE QUITE AS LOW AS WINDS SHOULD NOT BE QUITE AS STRONG. HOWEVER...THERE IS STILL SOME BUST POTENTIAL FOR MIN TEMPS FRIDAY MORNING IF WINDS GO CALM RATHER THAN REMAINING AROUND 5MPH. THE LIGHT WIND WOULD BE JUST ENOUGH TO TO KEEP THE SFC STIRRED UP...LIMITING COOLING. ON THE OTHER HAND...IF THE SFC WINDS CAN MANAGE TO GO CALM...AND SKIES CLEAR OUT ENOUGH...ENHANCED RADIATIONAL COOLING AIDED BY SOME RESIDUAL SNOW COVER COULD ALLOW TEMPERATURES TO DROP EVEN LOWER THAN CURRENTLY ANTICIPATED. FOR THE WEEKEND AND INTO EARLY NEXT WEEK...WITH THE PATTERN REMAINING QUICKLY PROGRESSIVE...TEMPERATURES FOR THE WEEKEND SHOULD REBOUND BACK CLOSER TO SEASONAL NORMAL LEVELS. HIGHS SHOULD BE IN THE UPPER 20S TO LOWER 30S. THE LONG RANGE MODEL GUIDANCE IS INDICATING THE CHANCE FOR ANOTHER SHOT OF ARCTIC AIR WITH SUB-ZERO TEMPERATES BY MONDAY MORNING. THE LONG RANGE FORECAST PERIOD SHOULD BE DRY WITH THE NEXT CHANCE FOR ANY PCPN COMING EARLY NEXT WEEK AS THE NEXT CLIPPER MOVES THROUGH THE AREA. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * MVFR CIGS EXPECTED TO PREVAIL WITH TEMPORARY BREAKS TO VFR NEXT 1-2 HRS. * LIGHT SNOW/FLURRIES RETURN LATER THIS AFTERNOON AND THIS EVENING. MDB //DISCUSSION...UPDATED 06Z... AN UPPER TROUGH MOVING ACROSS THE AREA CONTINUES TO GENERATE SOME LIGHT SNOW ACROSS THE TERMINALS WHICH WILL BE EXITING IN THE NEXT FEW HOURS. CIGS ARE QUITE VARIABLE BUT MAINLY MVFR THOUGH THERE IS AN AREA OF VFR CIGS FROM THE CHICAGO METRO EASTWARD OVER LAKE MICHIGAN INTO THE GYY AREA. THIS LOOKS TO BE SHORT LIVED WITH MORE MVFR UPSTREAM WORKING ITS WAY TOWARD THIS AREA OF IMPROVEMENT. EXPECT VARIABLE MVFR CIGS THROUGH THIS AFTERNOON AND PROBABLY THE UPCOMING EVENING AS WELL. CANNOT RULE OUT ADDITIONAL VFR BREAKS THROUGH THE DAY THOUGH. ANOTHER TROUGH WILL BRING LIGHT SNOW AND FLURRIES TO THE TERMINALS THIS AFTERNOON INTO THIS EVENING. THIS LOOKS TO BE LIGHT OVERALL BUT SOME MINIMAL VSBY REDUCTION IS POSSIBLE AT TIMES SO WILL NEED TO MONITOR INTENSITY TRENDS LATER TODAY. WINDS WILL REMAIN WESTERLY THROUGH THE PERIOD WITH PERIODIC 15 TO 20 KT GUSTS DEVELOPING LATER THIS MORNING. MDB //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH CONFIDENCE IN MAINLY MVFR CIGS THROUGH THE AFTERNOON WITH TEMPORARY BREAKS TO VFR EARLY TONIGHT. * MEDIUM CONFIDENCE IN LIGHT SNOW/FLURRY POTENTIAL LATER THIS AFTERNOON AND THIS EVENING. LOW CONFIDENCE IN CIG/VSBY IMPACTS. MDB //OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z... TUESDAY...VFR DURING THE DAY. CHANCE OF LIGHT SNOW LATER TUESDAY NIGHT WITH MVFR/IFR POSSIBLE. WEDNESDAY...CHANCE OF LIGHT SNOW EARLY. MVFR/IFR POSSIBLE. THURSDAY...VFR. FRIDAY...VFR. SATURDAY...VFR. RATZER && .MARINE... 244 PM...AS LOW PRESSURE MOVES ACROSS NEW ENGLAND TONIGHT AND MONDAY...A WEAKER TROUGH WILL EXTEND WEST ACROSS THE LAKES REGION INCLUDING CENTRAL LAKE MICHIGAN THROUGH MONDAY AFTERNOON. THIS WILL ALLOW FOR NORTHERLY WINDS ACROSS THE NORTH HALF OF THE LAKE...WITH INCREASING WESTERLY WINDS ACROSS THE SOUTHERN THIRD OR QUARTER OF THE LAKE TONIGHT. THESE WESTERLY WINDS COULD INCREASE INTO THE 20-25KT RANGE MONDAY AFTERNOON INTO MONDAY EVENING AND TRENDS WILL NEED TO BE MONITORED WITH LATER FORECASTS. THIS TROUGH WILL DISSIPATE MONDAY EVENING AS A RIDGE OF HIGH PRESSURE MOVES ACROSS THE LAKE TUESDAY...WITH THE CENTER OF THE HIGH REMAINING ACROSS THE OHIO VALLEY. ON THE BACK SIDE OF THIS RIDGE...WINDS WILL TURN SOUTHERLY TUESDAY AFTERNOON AND QUICKLY INCREASE TO 30 KTS TUESDAY EVENING...AS A LARGE TROUGH OF LOW PRESSURE MOVES ACROSS THE MIDWEST AND WESTERN LAKES. CONFIDENCE REGARDING LOW END GALES IS LOW AT THIS DISTANCE BUT HAVE OPTED TO INCLUDE THEM ACROSS THE NORTH HALF. WINDS TURN WESTERLY AND DIMINISH WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING...AS THE TROUGH PASSES ACROSS THE LAKE. ANOTHER HIGH WILL MOVE FROM THE NORTHERN PLAINS THURSDAY TO ACROSS THE SOUTHERN LAKES REGION FRIDAY. ANOTHER LOW WILL QUICKLY MOVE ACROSS THE NORTHERN LAKES FRIDAY NIGHT. THE GRADIENT WILL TIGHTEN AHEAD OF THIS SYSTEM WITH A SHORT PERIOD OF GALES POSSIBLE. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 1121 PM CST Sun Dec 22 2013 .DISCUSSION... ISSUED 840 PM CST Sun Dec 22 2013 Storm system that brought the wintry weather to the region yesterday continues to push well of to our east this evening. Latest satellite and surface observations to our west indicate a decrease in cloud cover over parts of east central Iowa which was working its way east this evening. Latest RAP soundings not very optimistic with respect to eroding the low level moisture already in place so will continue to hold on to the cloud cover overnight. Despite the cloud cover, low level cold advection behind the storm system will drawn down some rather cold temps by morning with overnight lows in the single digits in our far northwest. Still seeing an occasional report of flurries to our west over eastern Iowa and west central IL so will hold on to the flurries for the overnight hours. Current zones are in good shape, so other than the usual tweaks to the evening hourly temperatures and winds, no significant enough changes were made to warrant an evening update. && .AVIATION... ISSUED 1110 PM CST Sun Dec 22 2013 Main forecast challenge will be with any appreciable clearing of the MVFR cigs across the area towards morning. Latest satellite data and surface obs showing the backedge of the cloud shield was still over east central Iowa late this evening, and tracking southeast at about 20 kts. This would put any clearing into PIA and SPI between 10z and 12z and to the east of CMI by 15z. Not very confident on that scenario, despite most models trending in that direction. HRRR has been the quickest with the backedge of the cloud shield progressing across our forecast area in the 06z-09z time frame, while the Nam-Wrf and local Wrf-ARW models were a bit more conservative in the clearing trend from west to east which we will go with during this forecast period. Still appears the 10z-12z time frame looks ok for PIA and SPI but the hi-res forecast soundings indicate the clouds will tend to slow down their eastward progression tomorrow morning just east of the I-55 corridor with additional stratocu clouds from the north possibly affecting our PIA and BMI TAF sites tomorrow afternoon. We should see any lingering MVFR/low VFR cigs dissipate by tomorrow evening across the north as Arctic high pressure settles in bringing in some very cold temperatures for tomorrow night. Surface winds will remain out of the west to northwest at 10 to 15 kts tonight...with speeds of from 12 to 17 kts on Monday with a few gusts at or above 20 kts at times tomorrow afternoon. Winds should diminish to around 10 kts from the northwest tomorrow evening. Smith && .PREV DISCUSSION... ISSUED 300 PM CST Sun Dec 22 2013 The short and medium range models are all in very good agreement that central and eastern IL will experience quite a range of temperatures during the next week as a series of northwest flow/clipper systems take aim at the upper Midwest. This type of flow also indicates that no major storms are on the horizon for the next several days either. SHORT TERM...Tonight through Tuesday Low level cyclonic flow from the storm system moving through the eastern Great Lakes will keep clouds and scattered snow flurries over the forecast area through tonight and into much of the day Monday. There may be a few breaks in areas south of a Jacksonville-SPI- DEC-Paris line Monday as surface ridging tries to nose into the area, but overall clouds will prevail. The clouds will not do much to keep us warmer since plenty of low level cold air upstream is poised to move into the area. Lows tonight will be in the single digits west of the Illinois River, with teens in central IL and and 20s in the southeast. Continued cold advection Monday will result in nearly steady temperatures or only very minor rises. Arctic high pressure with a central pressure around 1040 mb will drop into the mid MS Valley by daybreak Tuesday. This will give us very cold temperatures, with sub-zero readings west of I-55 and single digits in the rest of the forecast area. The gradient ahead of the high pressure area will be moderately strong, with surface winds 10-15 mph in the evening and around 10 mph overnight. The resulting wind chill values will be below zero north of I-70 with -10 to -17 north of I-72 later Monday evening into Tuesday morning. May need a wind chill advisory in later forecasts if this trend continues. The cold temperatures will continue on Christmas Eve as the high slowly moves across Illinois. However, a southerly flow is expected to develop Tuesday night, once again resulting in very little diurnal temperature swing. The next in a series of clipper systems will track into the upper Midwest later on Christmas Eve. The best lift with this system will be in WI and northern IL, but there is a chance for a little light snow by Christmas morning - mainly along the I-74 corridor. LONG TERM...Christmas Day through Sunday The cold front associated with the Christmas morning clipper will be approaching from the northwest by evening. Again, the best upper support will be to the north, so will keep the chances for snow along and north of I-74. The rest of the area will be mostly cloudy on Christmas Day with a few snow flurries at times. The southerly winds ahead of the front will allow temperatures to rebound into the 30s. However, this will be short lived after the front moves through Wednesday night. Highs Thursday will mainly be in the 20s, with lower to middle 30s in southeast IL. The coldest air with the next Arctic high will push in Friday morning, although at this time it does not appear that it will be as cold as the previous Arctic airmass. The upper level flow will back to more of a westerly/zonal flow by the weekend as an upper trough from the Canadian Rockies digs toward the southern Plains. The result for Illinois will be warmer, more seasonal temperatures for Saturday and Sunday. The GFS and European models are similar in indicating a cold front approaching Sunday. However, with high pressure expected to be parked over the southern states, moisture will be quite limited. Will hold off on chance PoPs for now, and go with a dry forecast since the higher probability appears to be toward the Great Lakes area. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1140 PM EST SUN DEC 22 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 245 PM EST SUN DEC 22 2013 AS THE MAJOR RAINMAKER CONTINUES TO MOVE QUICKLY AWAY FROM THE AREA...UPPER LEVEL FLOW WILL REMAIN STRONGLY CYCLONIC AS HIGH PRESSURE BUILDS INTO THE AREA. RESIDUAL LOW LEVEL MOISTURE AND THIS CYCLONIC FLOW MAY BE ABLE TO SQUEEZE OUT A FEW FLURRIES AT TIMES...BUT NOTHING OF SIGNIFICANCE. && .NEAR TERM /OVERNIGHT/... ISSUED AT 950 PM EST SUN DEC 22 2013 LOW STRATUS DECK REMAINS THIS EVENING ALONG WITH A FEW FLURRIES AND POCKETS OF LIGHT DRIZZLE. TEMPS CONTINUE TO SLOWLY BUT STEADILY FALL AS THE COLDER AIR SEEPS INTO THE REGION FROM THE WEST. MOST LOCATIONS WERE IN THE LOWER AND MIDDLE 30S AS OF 0230Z. ONLY SUBTLE ADJUSTMENTS NEEDED FOR THE EVENING UPDATE. EXPECT CLOUDS TO LINGER ALL NIGHT WITH STRATUS DECK ALL THE WAY BACK TO THE WEST OF THE MISSISSIPPI RIVER. FURTHERMORE...PRESENCE OF THE SLOW MOVING FRONTAL BOUNDARY ACROSS THE APPALACHIANS IS DELAYING EXPANSION OF HIGH PRESSURE EAST INTO THE OHIO VALLEY. DECIDED TO EXTEND CHANCES FOR FLURRIES THROUGH THE NIGHT AS WEAK INSTABILITY NOTED BENEATH THE INVERSION ON RAP SOUNDINGS AND FORCING ALOFT PRESENT. POCKETS OF DRIZZLE REMAIN POSSIBLE OVER EASTERN COUNTIES FOR THE DURATION OF THE EVENING BUT EXPECT A CHANGE TO FLURRIES IN THESE AREAS AS THE BOUNDARY LAYER COOLS. OVERNIGHT LOWS IN THE 20S LOOK REASONABLE. ZONE AND GRID UPDATES OUT. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... ISSUED AT 245 PM EST SUN DEC 22 2013 SURFACE HIGH PRESSURE WILL DOMINATE THE SHORT TERM PERIOD...ALTHOUGH AN UPPER LEVEL TROUGH AXIS WILL SWING THROUGH THE AREA TOMORROW NIGHT. WILL CARRY A SLIGHT CHANCE OF FLURRIES LATE TOMORROW INTO TOMORROW NIGHT...BUT AGAIN NO MEASURABLE POP AS MOISTURE IS LACKING TO SAY THE LEAST. ON TEMPS...CONSENSUS NUMBERS LOOK VERY REASONABLE GIVEN EXPECTED LOW LEVEL THICKNESSES. FEW TWEAKS WERE REQUIRED BUT GENERALLY STUCK CLOSE TO THESE NUMBERS. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... ISSUED AT 240 PM EST SUN DEC 22 2013 NO MAJOR WEATHER CONCERNS FOR THE EXTENDED WHICH SHOULD ALLOW RIVER FLOODING TO RUN ITS COURSE. THAT BEING SAID...MODELS IN GENERAL AGREEMENT THAT TWO DIFFERENT SYSTEMS WILL BRING POTENTIAL FOR MINOR PRECIPITATION WEDNESDAY NIGHT AND THURSDAY AS WELL AS SUNDAY. SO...KEPT SMALL REGIONAL ALLBLEND POPS. IT SHOULD BE COLD ENOUGH FOR ONLY SNOW AS PRECIPITATION TYPE WEDNESDAY NIGHT AND THURSDAY...BUT SOUTHWEST FLOW AHEAD OF LATE WEEKEND FRONTAL SYSTEM SUGGESTS POSSIBILITY EXISTS OF A MIX OF RAIN AND SNOW IF NOT JUST RAIN. ALLBLEND TEMPERATURES LOOK REASONABLE WITH AFTERNOON TEMPERATURES STARTING OFF IN THE 20S AND 30S AND THEN WARMING TO THE 30S AND 40S BY SATURDAY. && .AVIATION /DISCUSSION FOR THE 230600Z TAFS/... ISSUED AT 1140 PM EST SUN DEC 22 2013 WIDESPREAD MVFR CEILINGS AROUND 012-015 CONTINUE ACROSS THE AREA AS MOISTURE REMAINS TRAPPED BELOW AN INVERSION. SOME BRIEF PERIODS OF IFR CEILINGS 008-009 AGL ALONG WITH SOME FLURRIES POSSIBLE FOR THE REST OF THE NIGHT AS AN UPPER TROUGH MOVES THROUGH...BUT THESE CONDITIONS SHOULD NOT BE TOO WIDESPREAD OR PROLONGED IN NATURE. CLEARING LINE CURRENTLY OUT TOWARDS THE MISSISSIPPI RIVER...SO SO IT MAY BE LATE MORNING OR MIDDAY MONDAY BEFORE THE LOWER CEILINGS SCATTER OUT. SURFACE WINDS GENERALLY AT OR BELOW 12 KTS THROUGH 231800Z. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...NIELD NEAR TERM...RYAN SHORT TERM...NIELD LONG TERM...MK AVIATION...JAS VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
904 AM CST Mon Dec 23 2013 .UPDATE... ISSUED AT 901 AM CST MON DEC 23 2013 Updated pops, QPF, snow amounts, and sky to account for the small snow band that is moving across south central Kansas this morning. Snow accumulations will be under an inch with this activity. && .SYNOPSIS... ISSUED AT 850 AM CST MON DEC 23 2013 The 23.12Z 250 hPa map showed a highly meridional flow pattern across North America with northwesterly flow extending from the western Canadian prairies down towards the southern Rockies. Peak magnitudes were around 110 kt. More impressively, very strong southwesterly flow extended downstream of a longwave trof axis with peak magnitudes around 200 kt at Sept-Iles, QB. At 500 hPa, cold mid-level temperatures advected in the wake of trof with values at -32C at KDDC. The overall height pattern showed a trof axis from Ontario to western Texas. Another trof was moving onshore across British Columbia. At 700 hPa, neutral temperature change was noted at KDDC with the baroclinic boundary north of the forecast area. Slight warming was noted at 850 hPa for KDDC, up to -3C versus -7C 24 hours ago. More importantly, all the really cold air at these two constant pressure levels was north and northeast of the forecast area of responsibility. At the sfc, a stationary was backed up to the lee of the Rockies. KDDC WSR-88D in combination with surface observations indicated light snow across south central Kansas. && .SHORT TERM...(Today and tonight) ISSUED AT 344 AM CST MON DEC 23 2013 A deep upper level trough was pushing into the upper Midwest early this morning, and cold surface high pressure was building southward in its wake. Some light snow was noted over northern Kansas along the low to mid level baroclinic zone. But only very light accumulations are expected through 12-14z. The arctic surge will occur this morning, with a weakening pressure gradient by this afternoon. High temperatures will only be in the upper teens over the snow covered locations such as Dodge City and Larned, with some 20s over places with bare ground such as Garden City, Syracuse and Scott City. Low stratus will develop this morning as the cold advection spreads southward, but should erode by this afternoon with daytime heating. This cold surge will be very short lived since the next rapidly advancing shortwave trough will have moved over the western pacific into the western and northern United States instead of through Canada. Surface pressures will fall rapidly ahead of this feature tonight given the mid level flow across the Rockies, resulting in breezy south winds. Stronger south winds on the back side of an arctic airmass can feel quite chilly, and tonight will be no exception. Temperatures will start out cold, and despite the south winds, will fall well down into the lower teens, along with some single digits over snow covered areas. The south winds will eventually result in a warm up, which is described below in the long term discussion. .LONG TERM...(Tuesday through Sunday) ISSUED AT 254 AM CST MON DEC 23 2013 An upper level trough, which was located over the Gulf of Alaska earlier this morning, will move out of the northern Rockies and out into the plains on Tuesday. As this next system passes, a cold front will drop south across western Kansas. At this time moisture appears to be mainly confined to the mid and upper levels so the chance of precipitation still appears small, however there will be an increase in cloud cover late Tuesday and Tuesday night. Prior to the frontal passage the 850mb temperatures from the GFS and NAM are forecast to range from 4c to 8c which when mixing these temperatures down to the surface suggests that highs in the lower 50s will still be possible in areas without snow cover Tuesday afternoon given full sun. In areas where snow cover remains the highs are expected to average around 15 degrees cooler. On Wednesday the net 24 hour change in the 925mb and 850mb temperatures varies from -2 to -4c so a minor cool down is expected behind the cold front mid week. By late week westerly downslope flow will improve with 850mb temperatures trends indicating temperatures will warm out of the upper 30s to mid 40s and into at least the lower 50s on Friday and Saturday. Temperatures will be cooler in areas when some snow cover remains late week and early this weekend. && .AVIATION...(For the 12Z TAFS through 12Z Tuesday morning) ISSUED AT 504 AM CST MON DEC 23 2013 BUFR soundings and HRRR suggesting a period of IFR status cigs will be possible early this morning behind a cold front which at 10z was located just south of DDC and GCK. Surface observations and satellite loop not supporting this trend at this time, however with more of an easterly upslope flow developing early this morning between 12z and 18z will introduce low MVFR cigs and even a period of 3-5sm BR. A few flurries will be possible early this morning also ahead of an upper level trough that will cross western Kansas between 12z and 18z. Once this upper trough passes VFR conditions will develop at all three taf sites. Gusty northeast winds at immediately behind this front will subside to less than 10kts by 18z as an area of high pressure at the surface builds into the area from the north. && .PRELIMINARY POINT TEMPS/POPS... DDC 18 11 39 16 / 10 0 10 0 GCK 21 12 49 17 / 10 0 0 0 EHA 24 18 49 19 / 0 0 0 10 LBL 20 11 45 20 / 0 0 0 0 HYS 18 11 43 20 / 30 0 10 10 P28 21 10 35 15 / 50 0 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Sugden SYNOPSIS...Sugden SHORT TERM...Finch LONG TERM...Burgert AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
850 AM CST Mon Dec 23 2013 ...Update to synopsis... .SYNOPSIS... ISSUED AT 850 AM CST MON DEC 23 2013 The 23.12Z 250 hPa map showed a highly meridional flow pattern across North America with northwesterly flow extending from the western Canadian prairies down towards the southern Rockies. Peak magnitudes were around 110 kt. More impressively, very strong southwesterly flow extended downstream of a longwave trof axis with peak magnitudes around 200 kt at Sept-Iles, QB. At 500 hPa, cold mid-level temperatures advected in the wake of trof with values at -32C at KDDC. The overall height pattern showed a trof axis from Ontario to western Texas. Another trof was moving onshore across British Columbia. At 700 hPa, neutral temperature change was noted at KDDC with the baroclinic boundary north of the forecast area. Slight warming was noted at 850 hPa for KDDC, up to -3C versus -7C 24 hours ago. More importantly, all the really cold air at these two constant pressure levels was north and northeast of the forecast area of responsibility. At the sfc, a stationary was backed up to the lee of the Rockies. KDDC WSR-88D in combination with surface observations indicated light snow across south central Kansas. && .SHORT TERM...(Today and tonight) ISSUED AT 344 AM CST MON DEC 23 2013 A deep upper level trough was pushing into the upper Midwest early this morning, and cold surface high pressure was building southward in its wake. Some light snow was noted over northern Kansas along the low to mid level baroclinic zone. But only very light accumulations are expected through 12-14z. The arctic surge will occur this morning, with a weakening pressure gradient by this afternoon. High temperatures will only be in the upper teens over the snow covered locations such as Dodge City and Larned, with some 20s over places with bare ground such as Garden City, Syracuse and Scott City. Low stratus will develop this morning as the cold advection spreads southward, but should erode by this afternoon with daytime heating. This cold surge will be very short lived since the next rapidly advancing shortwave trough will have moved over the western pacific into the western and northern United States instead of through Canada. Surface pressures will fall rapidly ahead of this feature tonight given the mid level flow across the Rockies, resulting in breezy south winds. Stronger south winds on the back side of an arctic airmass can feel quite chilly, and tonight will be no exception. Temperatures will start out cold, and despite the south winds, will fall well down into the lower teens, along with some single digits over snow covered areas. The south winds will eventually result in a warm up, which is described below in the long term discussion. .LONG TERM...(Tuesday through Sunday) ISSUED AT 254 AM CST MON DEC 23 2013 An upper level trough, which was located over the Gulf of Alaska earlier this morning, will move out of the northern Rockies and out into the plains on Tuesday. As this next system passes, a cold front will drop south across western Kansas. At this time moisture appears to be mainly confined to the mid and upper levels so the chance of precipitation still appears small, however there will be an increase in cloud cover late Tuesday and Tuesday night. Prior to the frontal passage the 850mb temperatures from the GFS and NAM are forecast to range from 4c to 8c which when mixing these temperatures down to the surface suggests that highs in the lower 50s will still be possible in areas without snow cover Tuesday afternoon given full sun. In areas where snow cover remains the highs are expected to average around 15 degrees cooler. On Wednesday the net 24 hour change in the 925mb and 850mb temperatures varies from -2 to -4c so a minor cool down is expected behind the cold front mid week. By late week westerly downslope flow will improve with 850mb temperatures trends indicating temperatures will warm out of the upper 30s to mid 40s and into at least the lower 50s on Friday and Saturday. Temperatures will be cooler in areas when some snow cover remains late week and early this weekend. && .AVIATION...(For the 12Z TAFS through 12Z Tuesday morning) ISSUED AT 504 AM CST MON DEC 23 2013 BUFR soundings and HRRR suggesting a period of IFR status cigs will be possible early this morning behind a cold front which at 10z was located just south of DDC and GCK. Surface observations and satellite loop not supporting this trend at this time, however with more of an easterly upslope flow developing early this morning between 12z and 18z will introduce low MVFR cigs and even a period of 3-5sm BR. A few flurries will be possible early this morning also ahead of an upper level trough that will cross western Kansas between 12z and 18z. Once this upper trough passes VFR conditions will develop at all three taf sites. Gusty northeast winds at immediately behind this front will subside to less than 10kts by 18z as an area of high pressure at the surface builds into the area from the north. && .PRELIMINARY POINT TEMPS/POPS... DDC 18 11 39 16 / 10 0 10 0 GCK 21 12 49 17 / 10 0 0 0 EHA 24 18 49 19 / 0 0 0 10 LBL 20 11 45 20 / 0 0 0 0 HYS 18 11 43 20 / 30 0 10 10 P28 21 10 35 15 / 20 0 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Sugden SHORT TERM...Finch LONG TERM...Burgert AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
507 AM CST Mon Dec 23 2013 ...Updated aviation discussion... .SHORT TERM...(Today and tonight) ISSUED AT 344 AM CST MON DEC 23 2013 A deep upper level trough was pushing into the upper Midwest early this morning, and cold surface high pressure was building southward in its wake. Some light snow was noted over northern Kansas along the low to mid level baroclinic zone. But only very light accumulations are expected through 12-14z. The arctic surge will occur this morning, with a weakening pressure gradient by this afternoon. High temperatures will only be in the upper teens over the snow covered locations such as Dodge City and Larned, with some 20s over places with bare ground such as Garden City, Syracuse and Scott City. Low stratus will develop this morning as the cold advection spreads southward, but should erode by this afternoon with daytime heating. This cold surge will be very short lived since the next rapidly advancing shortwave trough will have moved over the western pacific into the western and northern United States instead of through Canada. Surface pressures will fall rapidly ahead of this feature tonight given the mid level flow across the Rockies, resulting in breezy south winds. Stronger south winds on the back side of an arctic airmass can feel quite chilly, and tonight will be no exception. Temperatures will start out cold, and despite the south winds, will fall well down into the lower teens, along with some single digits over snow covered areas. The south winds will eventually result in a warm up, which is described below in the long term discussion. .LONG TERM...(Tuesday through Sunday) ISSUED AT 254 AM CST MON DEC 23 2013 An upper level trough, which was located over the Gulf of Alaska earlier this morning, will move out of the northern Rockies and out into the plains on Tuesday. As this next system passes, a cold front will drop south across western Kansas. At this time moisture appears to be mainly confined to the mid and upper levels so the chance of precipitation still appears small, however there will be an increase in cloud cover late Tuesday and Tuesday night. Prior to the frontal passage the 850mb temperatures from the GFS and NAM are forecast to range from 4c to 8c which when mixing these temperatures down to the surface suggests that highs in the lower 50s will still be possible in areas without snow cover Tuesday afternoon given full sun. In areas where snow cover remains the highs are expected to average around 15 degrees cooler. On Wednesday the net 24 hour change in the 925mb and 850mb temperatures varies from -2 to -4c so a minor cool down is expected behind the cold front mid week. By late week westerly downslope flow will improve with 850mb temperatures trends indicating temperatures will warm out of the upper 30s to mid 40s and into at least the lower 50s on Friday and Saturday. Temperatures will be cooler in areas when some snow cover remains late week and early this weekend. && .AVIATION...(For the 12Z TAFS through 12Z Tuesday morning) ISSUED AT 504 AM CST MON DEC 23 2013 BUFR soundings and HRRR suggesting a period of IFR status cigs will be possible early this morning behind a cold front which at 10z was located just south of DDC and GCK. Surface observations and satellite loop not supporting this trend at this time, however with more of an easterly upslope flow developing early this morning between 12z and 18z will introduce low MVFR cigs and even a period of 3-5sm BR. A few flurries will be possible early this morning also ahead of an upper level trough that will cross western Kansas between 12z and 18z. Once this upper trough passes VFR conditions will develop at all three taf sites. Gusty northeast winds at immediately behind this front will subside to less than 10kts by 18z as an area of high pressure at the surface builds into the area from the north. && .PRELIMINARY POINT TEMPS/POPS... DDC 18 11 39 16 / 10 0 10 0 GCK 21 12 49 17 / 10 0 0 0 EHA 24 18 49 19 / 10 0 0 10 LBL 20 11 45 20 / 10 0 0 0 HYS 18 11 43 20 / 20 0 10 10 P28 21 10 35 15 / 30 0 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Finch LONG TERM...Burgert AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS GOODLAND KS
254 AM MST MON DEC 23 2013 .UPDATE... ISSUED AT 630 PM MST SUN DEC 22 2013 AT 0130Z LIGHT SNOW WAS BEING REPORTED PER AWOS OB AT WRAY COLORADO WITH YUMA WEBCAM SHOWING WHAT APPEARS TO BE LIGHT RAIN. TEMPERATURES IN THAT AREA CURRENTLY AROUND 36-37F. DESPITE RATHER LARGE T/TD SPREADS PRECIP IS REACHING THE GROUND. FOR THE LATEST UPDATE ADJUSTED TEMPERATURES/DEWPOINTS AND WINDS BASED ON CURRENT OBS AND 23Z HRRR WHICH HAS A VERY GOOD HANDLE ON CURRENT SITUATION. COMBINATION OF LOW LEVEL FORCING FROM WIND SHIFT ASSOCIATED WITH APPROACHING COLD FRONT AND UPPER DISTURBANCE PRODUCING LIGHT RAIN/SNOW FROM YUMA EAST THROUGH PARTS OF FAR SOUTHWEST NEBRASKA. CURRENT TREND ON TRACK WITH LATEST FORECAST...ADJUSTMENT WAS MADE TO UP THE POPS FASTER ACROSS THE FAR NORTH. WILL AWAIT THE 00Z RUC/HRRR/NAM BEFORE MAKING FURTHER ADJUSTMENTS THIS EVENING. UPDATE ISSUED AT 410 PM MST SUN DEC 22 2013 UPDATE REQUIRED TO PUSH BACK ONSET OF SNOWFALL...ESPECIALLY EARLY TONIGHT. PREVIOUS FORECAST HAD SNOW ALREADY FALLING ACROSS THE NORTHWEST PORTION OF THE AREA. LATEST MODEL UPDATES...RADAR AND SFC OBS SHOW SNOW WELL TO THE NORTHWEST OF THE AREA. NOT EXPECTING ANY PRECIP TO DEVELOP IN THE FORECAST AREA FOR ANOTHER FEW HOURS. THERE IS ALSO SOME AGREEMENT THAT THERE WILL BE TWO SEPARATE AREAS OF PRECIPITATION FOCUS...THE FIRST MOVES DOWN FROM WESTERN NEBRASKA/FAR NORTHEAST COLORADO SLIDING SOUTHEAST AND MAINLY IMPACTING THE THE NORTHERN THROUGH EASTERN PARTS OF THE AREA. A SECOND LESS DYNAMIC SYSTEM MOVES DOWN INTO EASTERN COLORADO. THE HEIGHT OF THE PRECIPITATION AND BEST CHANCE FOR LIGHT SNOWFALL ACCUMULATIONS WILL BE IN THE 02Z-11Z TIMEFRAME WITH A QUICKLY DECREASE SHORTLY THEREAFTER. STILL LOOKING AT TOTAL SNOWFALL AMOUNTS UP TO AN INCH AND A HALF...MAYBE TWO INCHES PRIMARILY ALONG AND NORTH OF THE KS/NE BORDER WITH DECREASING AMOUNTS AS ONE TRAVELS SOUTH. FOR THE FAR SOUTHWEST AND SOUTHERN PARTS OF THE AREA NO SNOWFALL IS EXPECTED AT THIS TIME. MAY HAVE SOME GUSTY NORTHEAST WINDS TO 25 MPH TONIGHT AS WELL POSSIBLY CREATING A BIT OF BLOWING SNOW. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 1217 PM MST SUN DEC 22 2013 A NORTHERN STREAM TROUGH WILL PASS THROUGH THE REGION TONIGHT AS A IT MOVES EAST TOWARD THE GREAT LAKES. A SHORTWAVE WILL DIVE SOUTH ON THE WEST SIDE OF THE TROUGH ACROSS NORTHWEST KANSAS. NORTHWEST FLOW WILL FOLLOW ON MONDAY WITH SHORTWAVE RIDGING AND SUBSIDENCE. A SURFACE COLD FRONT WILL MOVE INTO THE CENTRAL PLAINS TONIGHT WITH HIGH PRESSURE BUILDING INTO THE REGION MONDAY. THE SHORTWAVE THAT COMES THROUGH THE FLOW TONIGHT HAS FAVORABLE PARAMETERS FOR SOME LIGHT SNOW ACROSS MAINLY THE NORTHERN HALF OF THE FA. FORCING AND ADEQUATE MOISTURE ARE INDICATED AND FORECAST SOUNDINGS SHOW ICE IN THE COLUMN. MODELS INDICATE THAT SNOW SHOULD BE ENDING QUICKLY AROUND 12Z MONDAY. TOTAL AMOUNTS SHOULD RANGE GENERALLY LESS THAN AN INCH AROUND THE I-70 CORRIDOR WITH 1 TO 2 INCHES NORTH OF THE INTERSTATE. SNOW SHOULD BEGIN BY LATE EVENING ACROSS THE NORTH AND THEN SPREAD SOUTHEAST THROUGH THE REST OF THE NIGHT. SNOW AMOUNTS AND WIND SHOULD BE BELOW ADVISORY CRITERIA. SUBSIDENCE WILL MOVE INTO THE FA BEHIND THE WAVE ON MONDAY WITH CLEARING SKIES. MIN TEMPERATURES TONIGHT WILL FALL INTO THE TEENS. MAX TEMPERATURES MONDAY WILL RANGE FROM THE LOWER 20S IN THE EAST TO LOW 30S IN THE WEST. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 254 AM MST MON DEC 23 2013 FOR THE EXTENDED FORECAST...A LARGE UPPER LEVEL PATTERN SHIFT IS EXPECTED WITH ANOTHER STRONG COLD FRONT PASSAGE THIS WEEKEND. INITIALLY...A LARGE UPPER LEVEL RIDGE OF HIGH PRESSURE WILL BE IN PLACE OVER THE ROCKIES FOR THURSDAY AND FRIDAY. ON SATURDAY...A STRONG SHORTWAVE TROUGH MOVES SOUTHEAST FROM SOUTHWEST CANADA TO THE GREAT LAKES. THIS STRONG SHORTWAVE WILL FORCE A COLD FRONT SOUTH WITH A COLD SURFACE HIGH BEHIND IT. THERE ARE SOME DIFFERENCES BETWEEN THE GFS AND EUROPEAN MODELS IN HANDLING THIS SURFACE HIGH. THE GFS SHOWS A MUCH STRONGER SURFACE HIGH...1050 MB...AND MUCH COLDER TEMPERATURES WHILE THE EUROPEAN MODEL ONLY HAS A 1039 SURFACE HIGH AND NEAR NORMAL TEMPERATURES. BASED ON THE STRENGTH OF THE FORECAST SHORTWAVE TROUGH AND THE VERY COLD HIGH THAT WAS ABLE TO DEVELOP THIS WEEKEND OVER CANADA...SIDED WITH THE COLDER SOLUTION FOR SUNDAY INTO EARLY NEXT WEEK. UNDER THE RIDGE OF HIGH PRESSURE FOR THURSDAY AND FRIDAY...DRY WEATHER AND WELL ABOVE NORMAL TEMPERATURES ARE EXPECTED. BASED ON THE OUTGOING FORECAST WITH THIS PACKAGE...HIGH TEMPERATURES FOR FRIDAY WOULD BE NEARLY 20 DEGREES ABOVE NORMAL. SOME OF THE GUIDANCE SUGGESTS EVEN WARMER TEMPERATURES BUT ONLY ADJUSTED UP SLIGHTLY FROM ALLBLEND IN COLLABORATION WITH NEIGHBORING OFFICES. DRY WEATHER SHOULD CONTINUE INTO SATURDAY. THE QUESTION OF TEMPERATURES WILL REMAIN ON SATURDAY DUE TO TIMING OF THE FRONTAL PASSAGE. AS OF RIGHT NOW...THE FRONT LOOKS TO COME THROUGH LATER IN THE DAY SO ONE LAST DAY OF MILD TEMPERATURES MAY BE IN STORE. FOR SATURDAY NIGHT INTO SUNDAY...TEMPERATURES WILL DROP TO NEAR NORMAL OR SLIGHTLY BELOW NORMAL. IF THE GFS MODEL AND THE STRONGER ARCTIC SURFACE HIGH PANS OUT...THEN TEMPERATURES WOULD BE COLDER THAN PRESENTLY ADVERTISED. AS THE SOUTHWESTERN EDGE OF THE SHORTWAVE TROUGH PASSES OVER...SOME LIGHT SNOW MAY BE POSSIBLE. ONLY LIGHT QPF WAS SUGGESTED BY THE 00Z MODEL RUNS SO HAVE KEPT POPS AT SLIGHT CHANCE. THERE APPEARS TO BE SOME DRY AIR THAT WOULD NEED TO BE OVERCOME SO CONFIDENCE IN THESE POPS IS EVEN SOMEWHAT LOW. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1020 PM MST SUN DEC 22 2013 KGLD...MVFR/IFR CIGS WITH LIGHT SNOW EXPECTED FROM TAF ISSUANCE THROUGH 08Z OR SO WITH CIG RESTRICTIONS FROM 08Z THROUGH 16Z. WINDS GENERALLY FROM THE NORTHEAST AT 10-15KTS MAY HAVE SOME GUSTINESS FOR A SHORT DURATION AS FRONTAL BOUNDARY MOVES THROUGH IN THE 06Z-08Z TIMEFRAME. AFTER 16Z CIGS QUICKLY RISE TO VFR WITH ONLY SOME HIGH CLOUDS EXPECTED BY VERY LATE IN THE AFTERNOON...SLOWLY THICKENING DURING THE NIGHT. KMCK...MVFR/IFR CIGS WITH LIGHT SNOW EXPECTED THROUGH 09Z OR SO WITH MVFR CIGS EXPECTED UP THROUGH 22Z OR SO BEFORE QUICKLY RISING TO VFR SHORTLY AFTER WITH SKC CONDITIONS. WINDS AT TAF ISSUANCE FROM THE NORTHEAST AT 10-15KTS BECOMING LGT/VRB BY 16Z THEN SLOWLY BECOMING LIGHT FROM THE EAST/SOUTHEAST UNDER 10KTS THROUGH THE REST OF THE TAF PERIOD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...99 SHORT TERM...FS LONG TERM...RRH AVIATION...99
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1020 PM MST SUN DEC 22 2013 .UPDATE... ISSUED AT 630 PM MST SUN DEC 22 2013 AT 0130Z LIGHT SNOW WAS BEING REPORTED PER AWOS OB AT WRAY COLORADO WITH YUMA WEBCAM SHOWING WHAT APPEARS TO BE LIGHT RAIN. TEMPERATURES IN THAT AREA CURRENTLY AROUND 36-37F. DESPITE RATHER LARGE T/TD SPREADS PRECIP IS REACHING THE GROUND. FOR THE LATEST UPDATE ADJUSTED TEMPERATURES/DEWPOINTS AND WINDS BASED ON CURRENT OBS AND 23Z HRRR WHICH HAS A VERY GOOD HANDLE ON CURRENT SITUATION. COMBINATION OF LOW LEVEL FORCING FROM WIND SHIFT ASSOCIATED WITH APPROACHING COLD FRONT AND UPPER DISTURBANCE PRODUCING LIGHT RAIN/SNOW FROM YUMA EAST THROUGH PARTS OF FAR SOUTHWEST NEBRASKA. CURRENT TREND ON TRACK WITH LATEST FORECAST...ADJUSTMENT WAS MADE TO UP THE POPS FASTER ACROSS THE FAR NORTH. WILL AWAIT THE 00Z RUC/HRRR/NAM BEFORE MAKING FURTHER ADJUSTMENTS THIS EVENING. UPDATE ISSUED AT 410 PM MST SUN DEC 22 2013 UPDATE REQUIRED TO PUSH BACK ONSET OF SNOWFALL...ESPECIALLY EARLY TONIGHT. PREVIOUS FORECAST HAD SNOW ALREADY FALLING ACROSS THE NORTHWEST PORTION OF THE AREA. LATEST MODEL UPDATES...RADAR AND SFC OBS SHOW SNOW WELL TO THE NORTHWEST OF THE AREA. NOT EXPECTING ANY PRECIP TO DEVELOP IN THE FORECAST AREA FOR ANOTHER FEW HOURS. THERE IS ALSO SOME AGREEMENT THAT THERE WILL BE TWO SEPARATE AREAS OF PRECIPITATION FOCUS...THE FIRST MOVES DOWN FROM WESTERN NEBRASKA/FAR NORTHEAST COLORADO SLIDING SOUTHEAST AND MAINLY IMPACTING THE THE NORTHERN THROUGH EASTERN PARTS OF THE AREA. A SECOND LESS DYNAMIC SYSTEM MOVES DOWN INTO EASTERN COLORADO. THE HEIGHT OF THE PRECIPITATION AND BEST CHANCE FOR LIGHT SNOWFALL ACCUMULATIONS WILL BE IN THE 02Z-11Z TIMEFRAME WITH A QUICKLY DECREASE SHORTLY THEREAFTER. STILL LOOKING AT TOTAL SNOWFALL AMOUNTS UP TO AN INCH AND A HALF...MAYBE TWO INCHES PRIMARILY ALONG AND NORTH OF THE KS/NE BORDER WITH DECREASING AMOUNTS AS ONE TRAVELS SOUTH. FOR THE FAR SOUTHWEST AND SOUTHERN PARTS OF THE AREA NO SNOWFALL IS EXPECTED AT THIS TIME. MAY HAVE SOME GUSTY NORTHEAST WINDS TO 25 MPH TONIGHT AS WELL POSSIBLY CREATING A BIT OF BLOWING SNOW. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 1217 PM MST SUN DEC 22 2013 A NORTHERN STREAM TROUGH WILL PASS THROUGH THE REGION TONIGHT AS A IT MOVES EAST TOWARD THE GREAT LAKES. A SHORTWAVE WILL DIVE SOUTH ON THE WEST SIDE OF THE TROUGH ACROSS NORTHWEST KANSAS. NORTHWEST FLOW WILL FOLLOW ON MONDAY WITH SHORTWAVE RIDGING AND SUBSIDENCE. A SURFACE COLD FRONT WILL MOVE INTO THE CENTRAL PLAINS TONIGHT WITH HIGH PRESSURE BUILDING INTO THE REGION MONDAY. THE SHORTWAVE THAT COMES THROUGH THE FLOW TONIGHT HAS FAVORABLE PARAMETERS FOR SOME LIGHT SNOW ACROSS MAINLY THE NORTHERN HALF OF THE FA. FORCING AND ADEQUATE MOISTURE ARE INDICATED AND FORECAST SOUNDINGS SHOW ICE IN THE COLUMN. MODELS INDICATE THAT SNOW SHOULD BE ENDING QUICKLY AROUND 12Z MONDAY. TOTAL AMOUNTS SHOULD RANGE GENERALLY LESS THAN AN INCH AROUND THE I-70 CORRIDOR WITH 1 TO 2 INCHES NORTH OF THE INTERSTATE. SNOW SHOULD BEGIN BY LATE EVENING ACROSS THE NORTH AND THEN SPREAD SOUTHEAST THROUGH THE REST OF THE NIGHT. SNOW AMOUNTS AND WIND SHOULD BE BELOW ADVISORY CRITERIA. SUBSIDENCE WILL MOVE INTO THE FA BEHIND THE WAVE ON MONDAY WITH CLEARING SKIES. MIN TEMPERATURES TONIGHT WILL FALL INTO THE TEENS. MAX TEMPERATURES MONDAY WILL RANGE FROM THE LOWER 20S IN THE EAST TO LOW 30S IN THE WEST. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 155 PM MST SUN DEC 22 2013 DRY AND MILD THROUGH THE LONG TERM WITH A FEW WEAK COLD FRONTS DURING THE WEEK. ONLY CHANCE OF PRECIP IN THE LONG TERM LOOKS TO BE ON SATURDAY NIGHT INTO SUNDAY. MON NIGHT...HIGH PRESSURE WILL BE IN PLACE ACROSS THE CENTRAL AND NORTHERN PLAINS AS SOUTHWESTERLY MID-LEVEL FLOW BRINGS SOMEWHAT MILDER AIR TO THE HIGH PLAINS. LOWS WILL BE NEAR NORMAL. TUESDAY...MILD AS A COLD FRONT APPROACHES FROM THE NORTHWEST. H5 SHORTWAVE RIDGE WILL MOVE ACROSS THE CENTRAL TO NORTHERN PLAINS. AT THE SURFACE A LEE SIDE TROUGH WILL DEVELOP IN EASTERN COLORADO DURING THE AFTERNOON WITH THE PRESSURE GRADIENT SUPPORTING A MILD BREEZE OUT OF THE SOUTH/SOUTHWEST. INCREASING CLOUDS DURING THE MORNING AND INTO THE AFTERNOON. COLD FRONT WILL MOVE THROUGH IN THE AFTERNOON BRINGING A WIND SHIFT AND CLEARING SKIES. NAM/NAM 4KM NEST SPEEDS UP THE FRONTAL TIMING...SO TUESDAY HAS THE POTENTIAL TO TURN OUT EVEN SUNNIER THAN CURRENTLY FORECAST. REGARDLESS OF TIMING...PRECIP CHANCES ARE NEAR NIL. TUESDAY NIGHT...CHRISTMAS EVE...AIR MASS BEHIND THE FRONT IS COOL AND DRY...AND THUS PRECIPITATION IS NOT EXPECTED. WINDS BECOME LIGHT BEYOND THE FRONT...AND SKIES WILL BE MOSTLY CLEAR. WEDNESDAY...CHRISTMAS...SUNNY AND SEASONABLE WITH LIGHT WINDS. HIGH PRESSURE WILL AGAIN BUILD ACROSS THE CENTRAL PLAINS IN THE WAKE OF TUESDAY NIGHTS WEAK COLD FRONT...WITH HIGH TEMPS EXPECTED TO BE NEAR TO ABOVE NORMAL /MID 40S/. IN THE EXTENDED /WED NIGHT THRU SATURDAY NIGHT/...DRY AND MILD FOR THE MOST PART WITH CHANCE OF PRECIP OVER THE WEEKEND. A REINFORCING SHOT OF COLD AIR WILL DROP THROUGH THE NORTHERN PLAINS ON WED NIGHT INTO THURSDAY...BUT THIS LOOKS TO BE TRENDING FARTHER EAST WITH EACH RUN OF GUIDANCE. THUS...EXPECT THIS AIR MASS NOT TO EFFECT THE CWA AND TEMPS TO BE MILD THURSDAY FRIDAY AND SATURDAY. FRI AND SAT LOOK ESPECIALLY MILD...WITH 850MB TEMPS ABOUT 10 DEG C ABOVE NORMAL AND SOUTHWESTERLY FLOW FROM THE SURFACE TO ABOUT 850MB. ON SATURDAY NIGHT A COLD FRONT WILL APPROACH FROM THE NORTH...WHICH WILL BRING A CHANCE OF PRECIP AND COLDER AIR. SET UP DOES NOT LOOK ESPECIALLY VIGOROUS...BUT AT THIS POINT LOOKS TO BE THE BEST CHANCE FOR PRECIP THE AREA HAS SEEN IN A WHILE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1020 PM MST SUN DEC 22 2013 KGLD...MVFR/IFR CIGS WITH LIGHT SNOW EXPECTED FROM TAF ISSUANCE THROUGH 08Z OR SO WITH CIG RESTRICTIONS FROM 08Z THROUGH 16Z. WINDS GENERALLY FROM THE NORTHEAST AT 10-15KTS MAY HAVE SOME GUSTINESS FOR A SHORT DURATION AS FRONTAL BOUNDARY MOVES THROUGH IN THE 06Z-08Z TIMEFRAME. AFTER 16Z CIGS QUICKLY RISE TO VFR WITH ONLY SOME HIGH CLOUDS EXPECTED BY VERY LATE IN THE AFTERNOON...SLOWLY THICKENING DURING THE NIGHT. KMCK...MVFR/IFR CIGS WITH LIGHT SNOW EXPECTED THROUGH 09Z OR SO WITH MVFR CIGS EXPECTED UP THROUGH 22Z OR SO BEFORE QUICKLY RISING TO VFR SHORTLY AFTER WITH SKC CONDITIONS. WINDS AT TAF ISSUANCE FROM THE NORTHEAST AT 10-15KTS BECOMING LGT/VRB BY 16Z THEN SLOWLY BECOMING LIGHT FROM THE EAST/SOUTHEAST UNDER 10KTS THROUGH THE REST OF THE TAF PERIOD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...99 SHORT TERM...FS LONG TERM...JJM AVIATION...99
AREA FORECAST DISCUSSION
NWS GRAY ME
1200 PM EST MON DEC 23 2013 .SYNOPSIS... A WAVE OF LOW PRESSURE WILL RIDE NORTHEAST ALONG A COLD FRONT THIS AFTERNOON, PRODUCING FREEZING RAIN AND A WINTRY MIX OF PRECIPITATION ACROSS MUCH OF THE AREA. THE COLD FRONT WILL FINALLY MOVE OUT TO SEA BY EVENING. HIGH PRESSURE AND COLDER AIR WILL THEN BUILD OVER THE REGION FOR THE MIDWEEK PERIOD. LOW PRESSURE WILL PASS NORTH OF THE AREA AND DRAG A TRAILING COLD FRONT ACROSS THE REGION EARLY FRIDAY FOLLOWED BY HIGH PRESSURE FOR LATE FRIDAY AND SATURDAY. && .NEAR TERM /UNTIL 5 PM THIS AFTERNOON/... 1155 AM...ACROSS THE LOWER CONNECTICUT VALLEY ZONES TEMPERATURES HAVE GRADUALLY WARMED ABOVE FREEZING AND THE STEADIER PRECIPITATION HAS ENDED. THEREFORE...WE`VE ALLOWED THE FREEZING RAIN ADVISORY TO EXPIRE THERE. OTHERWISE...ONLY MINOR ADJUSTMENTS FOR THIS ESTF UPDATE. PREV DISC... 935 AM...THIS FINAL ROUND OF FREEZING RAIN WILL PRODUCE UP TO AN ADDITIONAL 1/3 TO AS MUCH AS 1/2 INCH OF ICE BEFORE IT ENDS FROM SOUTHWEST TO NORTHEAST ACROSS THE AREA DURING THE AFTERNOON HOURS. THE ICE STORM WARNING HAS BEEN EXTENDED THROUGH 4 PM SINCE THIS AREA HAD THE GREATEST ICE ACCRETION PRIOR TO TODAY`S EVENT AND IS MOST VULNERABLE TO THE ADDITIONAL GLAZE. ELSEWHERE...I EXPECT TOTAL ICE ACCRETION TO BE UNDER 1/2 INCH AND IN THE ADVISORY CATEGORY. PREV DISC... 659 AM...I MADE SOME MINOR ADJUSTMENTS TO 1ST PERIOD GRIDS TO REFLECT CURRENT MESONET AS WELL AS RADAR TRENDS. ON THE WATERS...I EXTENDED THE CURRENT SMALL CRAFT ADVISORY THROUGH LATE TONIGHT. PREV DISC... UPDATE...MADE A FEW MINOR CHANGES TO THE GRIDS TO ACCOUNT FOR CURRENT OBSERVATIONAL TRENDS. HAVE ALSO DELAYED THE TIMING OF CATEGORICAL POP UNTIL AFTER 12Z BASED ON UPSTREAM OBS. PREVIOUS DISCUSSION...COLD AIR DAMMING REMAINS FIRMLY ENTRENCHED E OF THE MTNS THIS MORNING. ONLY RELATIVE WARMTH TO BE FOUND ACROSS THE CWFA IS IN THE CT RIVER VALLEY...WHERE READINGS ARE IN THE MID 30S. THIS IS THE CRITICAL PART OF THE FORECAST...AS WEAK LOW PRES AND SLUG OF PCPN LIFTS NEWD ALONG THE EAST COAST. THRU THIS MORNING THERE IS NO REAL MECHANISM TO SCOUR OUT THE LLVL COLD AIR. SO THE EXPECTATION IS THAT AREAS BELOW FREEZING WILL REMAIN THAT WAY...PROBABLY INTO THE AFTERNOON. RECENT RAP AND HRRR RUNS KEEP MUCH OF THE AREA BELOW FREEZING THRU 18Z. H8 TEMPS ARE COOLING SLIGHTLY...BUT 06Z GYX SOUNDING CONFIRMS THAT WE STILL HAVE A WARM NOSE OF +10 C AT 900 MB. AS THE COLUMN RE-SATURATES AND PCPN BEGINS FALLING...FZRA IS REALLY THE ONLY SCENARIO FOR MUCH OF THE AREA. THE CT RIVER VALLEY AND POSSIBLY THE IMMEDIATE COASTLINE WILL SEE JUST RNFL WITH TEMPS ABOVE FREEZING. IN THE FAR N AROUND JACKMAN...COLD AIR IS STILL DEEP ENOUGH FOR A MIX OF PL OR SN AT TIMES. NAM12 ACTUALLY HAS A REALLY GOOD HANDLE ON THERMAL PROFILE ATTM...SO BASED WX GRIDS OFF MODEL THICKNESS VALUES. FOR QPF A BLEND OF THE 23/00Z ECMWF AND NERFC WAS PREFERRED. THIS HAD GENERALLY 0.25 INCHES QPF RUNNING FROM KCON THRU KLEW AND TO KAUG. THE COAST WAS CLOSE TO 0.50 INCHES. USING THESE VALUES AND ACCOUNTING FOR SOME LOSS TO RUNOFF AND GRADUAL SURFACE WARMING...ICE ACCRETION VALUES OF AN ADDITIONAL 0.1 TO 0.25 INCHES IS POSSIBLE. THE GREATEST THREAT FOR ADDITIONAL SIGNIFICANT ICE ACCUMULATION IS JUST INLAND FROM THE COAST TO ABOUT A KLEW TO KAUG LINE. ADDITIONALLY FZRA WILL BE LIKELY DURING THE MORNING COMMUTE...WHICH WILL ADD TO THE HAZARD. GIVEN THESE EXPECTATIONS HAVE ADJUSTED HEADLINES TO MATCH. HAVE DROPPED WARNINGS ACROSS NH...AND CONVERTED COOS COUNTY TO A WINTER WX ADVISORY. NRN CARROLL COUNTY WILL BE INCLUDED WITH FZRA ADVISORY TO THE S. WILL ALLOW THE WRN NH ZONES TO EXPIRE MID MORNING. WINTER STORM WARNINGS IN NRN ME MTNS WILL ALSO BE DROPPED IN FAVOR OF WINTER WX ADVISORIES FOR COMBINATION OF SN AND FZRA. ICE STORM WARNINGS WILL REMAIN AS IS. EVEN THOUGH SOME AREAS MAY NOT SEE 0.5 INCHES OF ICE ACCRETION...CONFUSION OF DOWNGRADING THE HEADLINE AS FZRA IMPACTS MORNING COMMUTE ARGUED FOR THE CONTINUITY. && .SHORT TERM /5 PM THIS AFTERNOON THROUGH 6 PM TUESDAY/... S/WV TROF DROPPING THRU THE OHIO VALLEY WILL FINALLY BE THE IMPETUS THAT PUSHES FRONTAL BOUNDARY THRU THE REGION. AS FLOW BECOMES NW AND CAA COMMENCES WE WILL FINALLY MIX OUT THE LLVLS OF THE ATMOSPHERE. GIVEN SUCH WARMTH ALOFT...THIS MAY ACTUALLY CAUSE TEMPS TO JUMP UP SEVERAL DEGREES IN A SHORT AMOUNT OF TIME. THIS IS THE MOST LIKELY TIME THAT HIGH TEMPS WILL BE REACHED. CROSS BARRIER FLOW AND UPPER TROF SWINGING OVERHEAD WILL ALSO SUPPORT SCT SHSN IN THE MTNS. SEASONABLY COLD AIR LURKING JUST OVER THE INTERNATIONAL BORDER WILL ONCE AGAIN RETURN FOR THE AREA TUE...WITH HIGHS REMAINING IN THE 20S. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... MODELS ARE FAIRLY SIMILAR FOR THE THE WEEK. HIGH PRESSURE WILL BUILD OVER THE AREA TUESDAY AND WEDNESDAY AND MOVE EAST OF THE AREA THURSDAY. LOW PRESSURE WILL TRAVEL NORTH OF NEW ENGLAND THROUGH SOUTHERN CANADA THURSDAY AND FRIDAY. A COLD FRONT WILL MOVE THROUGH MAINE AND NEW HAMPSHIRE LATE THURSDAY NIGHT. A WARM FRONT WILL MOVE NORTH OF THE AREA FRIDAY OR SATURDAY FOLLOWED BY A COLD FRONT SUNDAY OR MONDAY. THE MODELS DIFFER ON THE TIMING OF THE SYSTEM FOR NEXT WEEKEND WITH THE ECMWF BEING SLOWER AND TRACKING THE SURFACE LOW THROUGH MAINE VERSUS THE GFS TRACKING THE LOW NORTH OF THE ST LAWRENCE RIVER. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... SHORT TERM...LIFR AND IFR CONDITIONS WILL CONTINUE INTO THE EARLY AFTERNOON. FZRA AND FZDZ WILL CONTINUE AS WELL. BY THE LATE AFTERNOON NW WINDS WILL BEGIN SLOWLY CLEARING AND DRYING THE AREA OUT FROM W TO E. LONG TERM...EXPECT VFR THROUGH THE PERIOD. && .MARINE... SHORT TERM...MARGINAL SCA CONDITIONS WILL CONTINUE INTO THE EARLY AFTERNOON. WINDS WILL REMAIN MOSTLY BELOW 25 KTS...BUT SEAS WILL REMAIN NEAR 5 FT. CAA OVER THE WATERS TUE COULD BRINGS WINDS AND SEAS BACK TO SCA THRESHOLDS. LONG TERM...SMALL CRAFT CONDITIONS ARE POSSIBLE WEDNESDAY THROUGH FRIDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MEZ007>009. ICE STORM WARNING UNTIL 4 PM EST THIS AFTERNOON FOR MEZ012>014- 019>022-024>028. FREEZING RAIN ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MEZ018-023. NH...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR NHZ001-002. FREEZING RAIN ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR NHZ004-006-008>010-013-014. FREEZING RAIN ADVISORY UNTIL NOON EST TODAY FOR NHZ003-005-007. MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST TUESDAY FOR ANZ150-152-154. && $$ ES
AREA FORECAST DISCUSSION
NWS GRAY ME
939 AM EST MON DEC 23 2013 .SYNOPSIS... A WAVE OF LOW PRESSURE WILL RIDE NORTHEAST ALONG A COLD FRONT TODAY. THIS WILL SPREAD FREEZING RAIN AND A WINTRY MIX OF PRECIPITATION INTO THE AREA ONCE AGAIN. THE COLD FRONT WILL FINALLY MOVE OUT TO SEA LATE TODAY. HIGH PRESSURE AND COLDER AIR WILL THEN BUILD OVER THE REGION FOR THE MIDWEEK PERIOD. LOW PRESSURE WILL PASS NORTH OF THE AREA AND DRAG A TRAILING COLD FRONT ACROSS THE REGION EARLY FRIDAY FOLLOWED BY HIGH PRESSURE FOR LATE FRIDAY AND SATURDAY. && .NEAR TERM /UNTIL 5 PM THIS AFTERNOON/... 935 AM...THIS FINAL ROUND OF FREEZING RAIN WILL PRODUCE UP TO AN ADDITIONAL 1/3 TO AS MUCH AS 1/2 INCH OF ICE BEFORE IT ENDS FROM SOUTHWEST TO NORTHEAST ACROSS THE AREA DURING THE AFTERNOON HOURS. THE ICE STORM WARNING HAS BEEN EXTENDED THROUGH 4 PM SINCE THIS AREA HAD THE GREATEST ICE ACCRETION PRIOR TO TODAY`S EVENT AND IS MOST VULNERABLE TO THE ADDITIONAL GLAZE. ELSEWHERE...I EXPECT TOTAL ICE ACCRETION TO BE UNDER 1/2 INCH AND IN THE ADVISORY CATEGORY. PREV DISC... 659 AM...I MADE SOME MINOR ADJUSTMENTS TO 1ST PERIOD GRIDS TO REFLECT CURRENT MESONET AS WELL AS RADAR TRENDS. ON THE WATERS...I EXTENDED THE CURRENT SMALL CRAFT ADVISORY THROUGH LATE TONIGHT. PREV DISC... UPDATE...MADE A FEW MINOR CHANGES TO THE GRIDS TO ACCOUNT FOR CURRENT OBSERVATIONAL TRENDS. HAVE ALSO DELAYED THE TIMING OF CATEGORICAL POP UNTIL AFTER 12Z BASED ON UPSTREAM OBS. PREVIOUS DISCUSSION...COLD AIR DAMMING REMAINS FIRMLY ENTRENCHED E OF THE MTNS THIS MORNING. ONLY RELATIVE WARMTH TO BE FOUND ACROSS THE CWFA IS IN THE CT RIVER VALLEY...WHERE READINGS ARE IN THE MID 30S. THIS IS THE CRITICAL PART OF THE FORECAST...AS WEAK LOW PRES AND SLUG OF PCPN LIFTS NEWD ALONG THE EAST COAST. THRU THIS MORNING THERE IS NO REAL MECHANISM TO SCOUR OUT THE LLVL COLD AIR. SO THE EXPECTATION IS THAT AREAS BELOW FREEZING WILL REMAIN THAT WAY...PROBABLY INTO THE AFTERNOON. RECENT RAP AND HRRR RUNS KEEP MUCH OF THE AREA BELOW FREEZING THRU 18Z. H8 TEMPS ARE COOLING SLIGHTLY...BUT 06Z GYX SOUNDING CONFIRMS THAT WE STILL HAVE A WARM NOSE OF +10 C AT 900 MB. AS THE COLUMN RE-SATURATES AND PCPN BEGINS FALLING...FZRA IS REALLY THE ONLY SCENARIO FOR MUCH OF THE AREA. THE CT RIVER VALLEY AND POSSIBLY THE IMMEDIATE COASTLINE WILL SEE JUST RNFL WITH TEMPS ABOVE FREEZING. IN THE FAR N AROUND JACKMAN...COLD AIR IS STILL DEEP ENOUGH FOR A MIX OF PL OR SN AT TIMES. NAM12 ACTUALLY HAS A REALLY GOOD HANDLE ON THERMAL PROFILE ATTM...SO BASED WX GRIDS OFF MODEL THICKNESS VALUES. FOR QPF A BLEND OF THE 23/00Z ECMWF AND NERFC WAS PREFERRED. THIS HAD GENERALLY 0.25 INCHES QPF RUNNING FROM KCON THRU KLEW AND TO KAUG. THE COAST WAS CLOSE TO 0.50 INCHES. USING THESE VALUES AND ACCOUNTING FOR SOME LOSS TO RUNOFF AND GRADUAL SURFACE WARMING...ICE ACCRETION VALUES OF AN ADDITIONAL 0.1 TO 0.25 INCHES IS POSSIBLE. THE GREATEST THREAT FOR ADDITIONAL SIGNIFICANT ICE ACCUMULATION IS JUST INLAND FROM THE COAST TO ABOUT A KLEW TO KAUG LINE. ADDITIONALLY FZRA WILL BE LIKELY DURING THE MORNING COMMUTE...WHICH WILL ADD TO THE HAZARD. GIVEN THESE EXPECTATIONS HAVE ADJUSTED HEADLINES TO MATCH. HAVE DROPPED WARNINGS ACROSS NH...AND CONVERTED COOS COUNTY TO A WINTER WX ADVISORY. NRN CARROLL COUNTY WILL BE INCLUDED WITH FZRA ADVISORY TO THE S. WILL ALLOW THE WRN NH ZONES TO EXPIRE MID MORNING. WINTER STORM WARNINGS IN NRN ME MTNS WILL ALSO BE DROPPED IN FAVOR OF WINTER WX ADVISORIES FOR COMBINATION OF SN AND FZRA. ICE STORM WARNINGS WILL REMAIN AS IS. EVEN THOUGH SOME AREAS MAY NOT SEE 0.5 INCHES OF ICE ACCRETION...CONFUSION OF DOWNGRADING THE HEADLINE AS FZRA IMPACTS MORNING COMMUTE ARGUED FOR THE CONTINUITY. && .SHORT TERM /5 PM THIS AFTERNOON THROUGH 6 PM TUESDAY/... S/WV TROF DROPPING THRU THE OHIO VALLEY WILL FINALLY BE THE IMPETUS THAT PUSHES FRONTAL BOUNDARY THRU THE REGION. AS FLOW BECOMES NW AND CAA COMMENCES WE WILL FINALLY MIX OUT THE LLVLS OF THE ATMOSPHERE. GIVEN SUCH WARMTH ALOFT...THIS MAY ACTUALLY CAUSE TEMPS TO JUMP UP SEVERAL DEGREES IN A SHORT AMOUNT OF TIME. THIS IS THE MOST LIKELY TIME THAT HIGH TEMPS WILL BE REACHED. CROSS BARRIER FLOW AND UPPER TROF SWINGING OVERHEAD WILL ALSO SUPPORT SCT SHSN IN THE MTNS. SEASONABLY COLD AIR LURKING JUST OVER THE INTERNATIONAL BORDER WILL ONCE AGAIN RETURN FOR THE AREA TUE...WITH HIGHS REMAINING IN THE 20S. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... MODELS ARE FAIRLY SIMILAR FOR THE THE WEEK. HIGH PRESSURE WILL BUILD OVER THE AREA TUESDAY AND WEDNESDAY AND MOVE EAST OF THE AREA THURSDAY. LOW PRESSURE WILL TRAVEL NORTH OF NEW ENGLAND THROUGH SOUTHERN CANADA THURSDAY AND FRIDAY. A COLD FRONT WILL MOVE THROUGH MAINE AND NEW HAMPSHIRE LATE THURSDAY NIGHT. A WARM FRONT WILL MOVE NORTH OF THE AREA FRIDAY OR SATURDAY FOLLOWED BY A COLD FRONT SUNDAY OR MONDAY. THE MODELS DIFFER ON THE TIMING OF THE SYSTEM FOR NEXT WEEKEND WITH THE ECMWF BEING SLOWER AND TRACKING THE SURFACE LOW THROUGH MAINE VERSUS THE GFS TRACKING THE LOW NORTH OF THE ST LAWRENCE RIVER. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... SHORT TERM...LIFR AND IFR CONDITIONS WILL CONTINUE INTO THE EARLY AFTERNOON. FZRA AND FZDZ WILL CONTINUE AS WELL. BY THE LATE AFTERNOON NW WINDS WILL BEGIN SLOWLY CLEARING AND DRYING THE AREA OUT FROM W TO E. LONG TERM...EXPECT VFR THROUGH THE PERIOD. && .MARINE... SHORT TERM...MARGINAL SCA CONDITIONS WILL CONTINUE INTO THE EARLY AFTERNOON. WINDS WILL REMAIN MOSTLY BELOW 25 KTS...BUT SEAS WILL REMAIN NEAR 5 FT. CAA OVER THE WATERS TUE COULD BRINGS WINDS AND SEAS BACK TO SCA THRESHOLDS. LONG TERM...SMALL CRAFT CONDITIONS ARE POSSIBLE WEDNESDAY THROUGH FRIDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MEZ007>009. ICE STORM WARNING UNTIL 4 PM EST THIS AFTERNOON FOR MEZ012>014- 019>022-024>028. FREEZING RAIN ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MEZ018-023. NH...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR NHZ001-002. FREEZING RAIN ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR NHZ004-006-008>010-013-014. FREEZING RAIN ADVISORY UNTIL NOON EST TODAY FOR NHZ003-005-007. MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST TUESDAY FOR ANZ150-152-154. && $$ SCHWIBS
AREA FORECAST DISCUSSION
NWS GRAY ME
702 AM EST MON DEC 23 2013 .SYNOPSIS... A WAVE OF LOW PRESSURE WILL RIDE NORTHEAST ALONG A COLD FRONT TODAY. THIS WILL SPREAD FREEZING RAIN AND A WINTRY MIX OF PRECIPITATION INTO THE AREA ONCE AGAIN. THE COLD FRONT WILL FINALLY MOVE OUT TO SEA LATE TODAY. HIGH PRESSURE AND COLDER AIR WILL THEN BUILD OVER THE REGION FOR THE MIDWEEK PERIOD. LOW PRESSURE WILL PASS NORTH OF THE AREA AND DRAG A TRAILING COLD FRONT ACROSS THE REGION EARLY FRIDAY FOLLOWED BY HIGH PRESSURE FOR LATE FRIDAY AND SATURDAY. && .NEAR TERM /UNTIL 5 PM THIS AFTERNOON/... 659 AM...I MADE SOME MINOR ADJUSTMENTS TO 1ST PERIOD GRIDS TO REFLECT CURRENT MESONET AS WELL AS RADAR TRENDS. ON THE WATERS...I EXTENDED THE CURRENT SMALL CRAFT ADVISORY THROUGH LATE TONIGHT. PREV DISC... UPDATE...MADE A FEW MINOR CHANGES TO THE GRIDS TO ACCOUNT FOR CURRENT OBSERVATIONAL TRENDS. HAVE ALSO DELAYED THE TIMING OF CATEGORICAL POP UNTIL AFTER 12Z BASED ON UPSTREAM OBS. PREVIOUS DISCUSSION...COLD AIR DAMMING REMAINS FIRMLY ENTRENCHED E OF THE MTNS THIS MORNING. ONLY RELATIVE WARMTH TO BE FOUND ACROSS THE CWFA IS IN THE CT RIVER VALLEY...WHERE READINGS ARE IN THE MID 30S. THIS IS THE CRITICAL PART OF THE FORECAST...AS WEAK LOW PRES AND SLUG OF PCPN LIFTS NEWD ALONG THE EAST COAST. THRU THIS MORNING THERE IS NO REAL MECHANISM TO SCOUR OUT THE LLVL COLD AIR. SO THE EXPECTATION IS THAT AREAS BELOW FREEZING WILL REMAIN THAT WAY...PROBABLY INTO THE AFTERNOON. RECENT RAP AND HRRR RUNS KEEP MUCH OF THE AREA BELOW FREEZING THRU 18Z. H8 TEMPS ARE COOLING SLIGHTLY...BUT 06Z GYX SOUNDING CONFIRMS THAT WE STILL HAVE A WARM NOSE OF +10 C AT 900 MB. AS THE COLUMN RE-SATURATES AND PCPN BEGINS FALLING...FZRA IS REALLY THE ONLY SCENARIO FOR MUCH OF THE AREA. THE CT RIVER VALLEY AND POSSIBLY THE IMMEDIATE COASTLINE WILL SEE JUST RNFL WITH TEMPS ABOVE FREEZING. IN THE FAR N AROUND JACKMAN...COLD AIR IS STILL DEEP ENOUGH FOR A MIX OF PL OR SN AT TIMES. NAM12 ACTUALLY HAS A REALLY GOOD HANDLE ON THERMAL PROFILE ATTM...SO BASED WX GRIDS OFF MODEL THICKNESS VALUES. FOR QPF A BLEND OF THE 23/00Z ECMWF AND NERFC WAS PREFERRED. THIS HAD GENERALLY 0.25 INCHES QPF RUNNING FROM KCON THRU KLEW AND TO KAUG. THE COAST WAS CLOSE TO 0.50 INCHES. USING THESE VALUES AND ACCOUNTING FOR SOME LOSS TO RUNOFF AND GRADUAL SURFACE WARMING...ICE ACCRETION VALUES OF AN ADDITIONAL 0.1 TO 0.25 INCHES IS POSSIBLE. THE GREATEST THREAT FOR ADDITIONAL SIGNIFICANT ICE ACCUMULATION IS JUST INLAND FROM THE COAST TO ABOUT A KLEW TO KAUG LINE. ADDITIONALLY FZRA WILL BE LIKELY DURING THE MORNING COMMUTE...WHICH WILL ADD TO THE HAZARD. GIVEN THESE EXPECTATIONS HAVE ADJUSTED HEADLINES TO MATCH. HAVE DROPPED WARNINGS ACROSS NH...AND CONVERTED COOS COUNTY TO A WINTER WX ADVISORY. NRN CARROLL COUNTY WILL BE INCLUDED WITH FZRA ADVISORY TO THE S. WILL ALLOW THE WRN NH ZONES TO EXPIRE MID MORNING. WINTER STORM WARNINGS IN NRN ME MTNS WILL ALSO BE DROPPED IN FAVOR OF WINTER WX ADVISORIES FOR COMBINATION OF SN AND FZRA. ICE STORM WARNINGS WILL REMAIN AS IS. EVEN THOUGH SOME AREAS MAY NOT SEE 0.5 INCHES OF ICE ACCRETION...CONFUSION OF DOWNGRADING THE HEADLINE AS FZRA IMPACTS MORNING COMMUTE ARGUED FOR THE CONTINUITY. && .SHORT TERM /5 PM THIS AFTERNOON THROUGH 6 PM TUESDAY/... S/WV TROF DROPPING THRU THE OHIO VALLEY WILL FINALLY BE THE IMPETUS THAT PUSHES FRONTAL BOUNDARY THRU THE REGION. AS FLOW BECOMES NW AND CAA COMMENCES WE WILL FINALLY MIX OUT THE LLVLS OF THE ATMOSPHERE. GIVEN SUCH WARMTH ALOFT...THIS MAY ACTUALLY CAUSE TEMPS TO JUMP UP SEVERAL DEGREES IN A SHORT AMOUNT OF TIME. THIS IS THE MOST LIKELY TIME THAT HIGH TEMPS WILL BE REACHED. CROSS BARRIER FLOW AND UPPER TROF SWINGING OVERHEAD WILL ALSO SUPPORT SCT SHSN IN THE MTNS. SEASONABLY COLD AIR LURKING JUST OVER THE INTERNATIONAL BORDER WILL ONCE AGAIN RETURN FOR THE AREA TUE...WITH HIGHS REMAINING IN THE 20S. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... MODELS ARE FAIRLY SIMILAR FOR THE THE WEEK. HIGH PRESSURE WILL BUILD OVER THE AREA TUESDAY AND WEDNESDAY AND MOVE EAST OF THE AREA THURSDAY. LOW PRESSURE WILL TRAVEL NORTH OF NEW ENGLAND THROUGH SOUTHERN CANADA THURSDAY AND FRIDAY. A COLD FRONT WILL MOVE THROUGH MAINE AND NEW HAMPSHIRE LATE THURSDAY NIGHT. A WARM FRONT WILL MOVE NORTH OF THE AREA FRIDAY OR SATURDAY FOLLOWED BY A COLD FRONT SUNDAY OR MONDAY. THE MODELS DIFFER ON THE TIMING OF THE SYSTEM FOR NEXT WEEKEND WITH THE ECMWF BEING SLOWER AND TRACKING THE SURFACE LOW THROUGH MAINE VERSUS THE GFS TRACKING THE LOW NORTH OF THE ST LAWRENCE RIVER. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... SHORT TERM...LIFR AND IFR CONDITIONS WILL CONTINUE INTO THE EARLY AFTERNOON. FZRA AND FZDZ WILL CONTINUE AS WELL. BY THE LATE AFTERNOON NW WINDS WILL BEGIN SLOWLY CLEARING AND DRYING THE AREA OUT FROM W TO E. LONG TERM...EXPECT VFR THROUGH THE PERIOD. && .MARINE... SHORT TERM...MARGINAL SCA CONDITIONS WILL CONTINUE INTO THE EARLY AFTERNOON. WINDS WILL REMAIN MOSTLY BELOW 25 KTS...BUT SEAS WILL REMAIN NEAR 5 FT. CAA OVER THE WATERS TUE COULD BRINGS WINDS AND SEAS BACK TO SCA THRESHOLDS. LONG TERM...SMALL CRAFT CONDITIONS ARE POSSIBLE WEDNESDAY THROUGH FRIDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MEZ007>009. ICE STORM WARNING UNTIL NOON EST TODAY FOR MEZ012>014-019>022- 024>028. FREEZING RAIN ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MEZ018-023. NH...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR NHZ001-002. FREEZING RAIN ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR NHZ004-006-008>010-013-014. FREEZING RAIN ADVISORY UNTIL NOON EST TODAY FOR NHZ003-005-007. MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST TUESDAY FOR ANZ150-152-154. && $$ SCHWIBS
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
535 AM EST MON DEC 23 2013 .SYNOPSIS... A WAVE OF LOW PRESSURE WILL RIDE NORTHEAST ALONG A COLD FRONT TODAY. THIS WILL SPREAD FREEZING INTO THE AREA ONCE AGAIN. THE COLD FRONT WILL FINALLY MOVE OUT TO SEA LATE TODAY. HIGH PRESSURE WILL THEN BUILD OVER THE REGION TUESDAY AND WEDNESDAY. LOW PRESSURE WILL PASS NORTH OF THE AREA AND DRAG A TRAILING COLD FRONT ACROSS THE REGION EARLY FRIDAY FOLLOWED BY HIGH PRESSURE FOR LATE FRIDAY AND SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATE...MADE A FEW MINOR CHANGES TO THE GRIDS TO ACCOUNT FOR CURRENT OBSERVATIONAL TRENDS. HAVE ALSO DELAYED THE TIMING OF CATEGORICAL POP UNTIL AFTER 12Z BASED ON UPSTREAM OBS. PREVIOUS DISCUSSION...COLD AIR DAMMING REMAINS FIRMLY ENTRENCHED E OF THE MTNS THIS MORNING. ONLY RELATIVE WARMTH TO BE FOUND ACROSS THE CWFA IS IN THE CT RIVER VALLEY...WHERE READINGS ARE IN THE MID 30S. THIS IS THE CRITICAL PART OF THE FORECAST...AS WEAK LOW PRES AND SLUG OF PCPN LIFTS NEWD ALONG THE EAST COAST. THRU THIS MORNING THERE IS NO REAL MECHANISM TO SCOUR OUT THE LLVL COLD AIR. SO THE EXPECTATION IS THAT AREAS BELOW FREEZING WILL REMAIN THAT WAY...PROBABLY INTO THE AFTERNOON. RECENT RAP AND HRRR RUNS KEEP MUCH OF THE AREA BELOW FREEZING THRU 18Z. H8 TEMPS ARE COOLING SLIGHTLY...BUT 06Z GYX SOUNDING CONFIRMS THAT WE STILL HAVE A WARM NOSE OF +10 C AT 900 MB. AS THE COLUMN RE-SATURATES AND PCPN BEGINS FALLING...FZRA IS REALLY THE ONLY SCENARIO FOR MUCH OF THE AREA. THE CT RIVER VALLEY AND POSSIBLY THE IMMEDIATE COASTLINE WILL SEE JUST RNFL WITH TEMPS ABOVE FREEZING. IN THE FAR N AROUND JACKMAN...COLD AIR IS STILL DEEP ENOUGH FOR A MIX OF PL OR SN AT TIMES. NAM12 ACTUALLY HAS A REALLY GOOD HANDLE ON THERMAL PROFILE ATTM...SO BASED WX GRIDS OFF MODEL THICKNESS VALUES. FOR QPF A BLEND OF THE 23/00Z ECMWF AND NERFC WAS PREFERRED. THIS HAD GENERALLY 0.25 INCHES QPF RUNNING FROM KCON THRU KLEW AND TO KAUG. THE COAST WAS CLOSE TO 0.50 INCHES. USING THESE VALUES AND ACCOUNTING FOR SOME LOSS TO RUNOFF AND GRADUAL SURFACE WARMING...ICE ACCRETION VALUES OF AN ADDITIONAL 0.1 TO 0.25 INCHES IS POSSIBLE. THE GREATEST THREAT FOR ADDITIONAL SIGNIFICANT ICE ACCUMULATION IS JUST INLAND FROM THE COAST TO ABOUT A KLEW TO KAUG LINE. ADDITIONALLY FZRA WILL BE LIKELY DURING THE MORNING COMMUTE...WHICH WILL ADD TO THE HAZARD. GIVEN THESE EXPECTATIONS HAVE ADJUSTED HEADLINES TO MATCH. HAVE DROPPED WARNINGS ACROSS NH...AND CONVERTED COOS COUNTY TO A WINTER WX ADVISORY. NRN CARROLL COUNTY WILL BE INCLUDED WITH FZRA ADVISORY TO THE S. WILL ALLOW THE WRN NH ZONES TO EXPIRE MID MORNING. WINTER STORM WARNINGS IN NRN ME MTNS WILL ALSO BE DROPPED IN FAVOR OF WINTER WX ADVISORIES FOR COMBINATION OF SN AND FZRA. ICE STORM WARNINGS WILL REMAIN AS IS. EVEN THOUGH SOME AREAS MAY NOT SEE 0.5 INCHES OF ICE ACCRETION...CONFUSION OF DOWNGRADING THE HEADLINE AS FZRA IMPACTS MORNING COMMUTE ARGUED FOR THE CONTINUITY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... S/WV TROF DROPPING THRU THE OHIO VALLEY WILL FINALLY BE THE IMPETUS THAT PUSHES FRONTAL BOUNDARY THRU THE REGION. AS FLOW BECOMES NW AND CAA COMMENCES WE WILL FINALLY MIX OUT THE LLVLS OF THE ATMOSPHERE. GIVEN SUCH WARMTH ALOFT...THIS MAY ACTUALLY CAUSE TEMPS TO JUMP UP SEVERAL DEGREES IN A SHORT AMOUNT OF TIME. THIS IS THE MOST LIKELY TIME THAT HIGH TEMPS WILL BE REACHED. CROSS BARRIER FLOW AND UPPER TROF SWINGING OVERHEAD WILL ALSO SUPPORT SCT SHSN IN THE MTNS. SEASONABLY COLD AIR LURKING JUST OVER THE INTERNATIONAL BORDER WILL ONCE AGAIN RETURN FOR THE AREA TUE...WITH HIGHS REMAINING IN THE 20S. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... MODELS ARE FAIRLY SIMILAR FOR THE THE WEEK. HIGH PRESSURE WILL BUILD OVER THE AREA TUESDAY AND WEDNESDAY AND MOVE EAST OF THE AREA THURSDAY. LOW PRESSURE WILL TRAVEL NORTH OF NEW ENGLAND THROUGH SOUTHERN CANADA THURSDAY AND FRIDAY. A COLD FRONT WILL MOVE THROUGH MAINE AND NEW HAMPSHIRE LATE THURSDAY NIGHT. A WARM FRONT WILL MOVE NORTH OF THE AREA FRIDAY OR SATURDAY FOLLOWED BY A COLD FRONT SUNDAY OR MONDAY. THE MODELS DIFFER ON THE TIMING OF THE SYSTEM FOR NEXT WEEKEND WITH THE ECMWF BEING SLOWER AND TRACKING THE SURFACE LOW THROUGH MAINE VERSUS THE GFS TRACKING THE LOW NORTH OF THE ST LAWRENCE RIVER. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... SHORT TERM...LIFR AND IFR CONDITIONS WILL CONTINUE INTO THE EARLY AFTERNOON. FZRA AND FZDZ WILL CONTINUE AS WELL. BY THE LATE AFTERNOON NW WINDS WILL BEGIN SLOWLY CLEARING AND DRYING THE AREA OUT FROM W TO E. LONG TERM...EXPECT VFR THROUGH THE PERIOD. && .MARINE... SHORT TERM...MARGINAL SCA CONDITIONS WILL CONTINUE INTO THE EARLY AFTERNOON. WINDS WILL REMAIN MOSTLY BELOW 25 KTS...BUT SEAS WILL REMAIN NEAR 5 FT. CAA OVER THE WATERS TUE COULD BRINGS WINDS AND SEAS BACK TO SCA THRESHOLDS. LONG TERM...SMALL CRAFT CONDITIONS ARE POSSIBLE WEDNESDAY THROUGH FRIDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MEZ007>009. ICE STORM WARNING UNTIL NOON EST TODAY FOR MEZ012>014-019>022- 024>028. FREEZING RAIN ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MEZ018-023. NH...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR NHZ001-002. FREEZING RAIN ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR NHZ004-006-008>010-013-014. FREEZING RAIN ADVISORY UNTIL NOON EST TODAY FOR NHZ003-005-007. MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR ANZ150- 152-154. && $$ LEGRO/HAWLEY
AREA FORECAST DISCUSSION
NWS GRAY ME
402 AM EST MON DEC 23 2013 .SYNOPSIS... A WAVE OF LOW PRESSURE WILL RIDE NORTHEAST ALONG A COLD FRONT TODAY. THIS WILL SPREAD FREEZING INTO THE AREA ONCE AGAIN. THE COLD FRONT WILL FINALLY MOVE OUT TO SEA LATE TODAY. HIGH PRESSURE WILL THEN BUILD OVER THE REGION TUESDAY AND WEDNESDAY. LOW PRESSURE WILL PASS NORTH OF THE AREA AND DRAG A TRAILING COLD FRONT ACROSS THE REGION EARLY FRIDAY FOLLOWED BY HIGH PRESSURE FOR LATE FRIDAY AND SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... COLD AIR DAMMING REMAINS FIRMLY ENTRENCHED E OF THE MTNS THIS MORNING. ONLY RELATIVE WARMTH TO BE FOUND ACROSS THE CWFA IS IN THE CT RIVER VALLEY...WHERE READINGS ARE IN THE MID 30S. THIS IS THE CRITICAL PART OF THE FORECAST...AS WEAK LOW PRES AND SLUG OF PCPN LIFTS NEWD ALONG THE EAST COAST. THRU THIS MORNING THERE IS NO REAL MECHANISM TO SCOUR OUT THE LLVL COLD AIR. SO THE EXPECTATION IS THAT AREAS BELOW FREEZING WILL REMAIN THAT WAY...PROBABLY INTO THE AFTERNOON. RECENT RAP AND HRRR RUNS KEEP MUCH OF THE AREA BELOW FREEZING THRU 18Z. H8 TEMPS ARE COOLING SLIGHTLY...BUT 06Z GYX SOUNDING CONFIRMS THAT WE STILL HAVE A WARM NOSE OF +10 C AT 900 MB. AS THE COLUMN RE-SATURATES AND PCPN BEGINS FALLING...FZRA IS REALLY THE ONLY SCENARIO FOR MUCH OF THE AREA. THE CT RIVER VALLEY AND POSSIBLY THE IMMEDIATE COASTLINE WILL SEE JUST RNFL WITH TEMPS ABOVE FREEZING. IN THE FAR N AROUND JACKMAN...COLD AIR IS STILL DEEP ENOUGH FOR A MIX OF PL OR SN AT TIMES. NAM12 ACTUALLY HAS A REALLY GOOD HANDLE ON THERMAL PROFILE ATTM...SO BASED WX GRIDS OFF MODEL THICKNESS VALUES. FOR QPF A BLEND OF THE 23/00Z ECMWF AND NERFC WAS PREFERRED. THIS HAD GENERALLY 0.25 INCHES QPF RUNNING FROM KCON THRU KLEW AND TO KAUG. THE COAST WAS CLOSE TO 0.50 INCHES. USING THESE VALUES AND ACCOUNTING FOR SOME LOSS TO RUNOFF AND GRADUAL SURFACE WARMING...ICE ACCRETION VALUES OF AN ADDITIONAL 0.1 TO 0.25 INCHES IS POSSIBLE. THE GREATEST THREAT FOR ADDITIONAL SIGNIFICANT ICE ACCUMULATION IS JUST INLAND FROM THE COAST TO ABOUT A KLEW TO KAUG LINE. ADDITIONALLY FZRA WILL BE LIKELY DURING THE MORNING COMMUTE...WHICH WILL ADD TO THE HAZARD. GIVEN THESE EXPECTATIONS HAVE ADJUSTED HEADLINES TO MATCH. HAVE DROPPED WARNINGS ACROSS NH...AND CONVERTED COOS COUNTY TO A WINTER WX ADVISORY. NRN CARROLL COUNTY WILL BE INCLUDED WITH FZRA ADVISORY TO THE S. WILL ALLOW THE WRN NH ZONES TO EXPIRE MID MORNING. WINTER STORM WARNINGS IN NRN ME MTNS WILL ALSO BE DROPPED IN FAVOR OF WINTER WX ADVISORIES FOR COMBINATION OF SN AND FZRA. ICE STORM WARNINGS WILL REMAIN AS IS. EVEN THOUGH SOME AREAS MAY NOT SEE 0.5 INCHES OF ICE ACCRETION...CONFUSION OF DOWNGRADING THE HEADLINE AS FZRA IMPACTS MORNING COMMUTE ARGUED FOR THE CONTINUITY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... S/WV TROF DROPPING THRU THE OHIO VALLEY WILL FINALLY BE THE IMPETUS THAT PUSHES FRONTAL BOUNDARY THRU THE REGION. AS FLOW BECOMES NW AND CAA COMMENCES WE WILL FINALLY MIX OUT THE LLVLS OF THE ATMOSPHERE. GIVEN SUCH WARMTH ALOFT...THIS MAY ACTUALLY CAUSE TEMPS TO JUMP UP SEVERAL DEGREES IN A SHORT AMOUNT OF TIME. THIS IS THE MOST LIKELY TIME THAT HIGH TEMPS WILL BE REACHED. CROSS BARRIER FLOW AND UPPER TROF SWINGING OVERHEAD WILL ALSO SUPPORT SCT SHSN IN THE MTNS. SEASONABLY COLD AIR LURKING JUST OVER THE INTERNATIONAL BORDER WILL ONCE AGAIN RETURN FOR THE AREA TUE...WITH HIGHS REMAINING IN THE 20S. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... MODELS ARE FAIRLY SIMILAR FOR THE THE WEEK. HIGH PRESSURE WILL BUILD OVER THE AREA TUESDAY AND WEDNESDAY AND MOVE EAST OF THE AREA THURSDAY. LOW PRESSURE WILL TRAVEL NORTH OF NEW ENGLAND THROUGH SOUTHERN CANADA THURSDAY AND FRIDAY. A COLD FRONT WILL MOVE THROUGH MAINE AND NEW HAMPSHIRE LATE THURSDAY NIGHT. A WARM FRONT WILL MOVE NORTH OF THE AREA FRIDAY OR SATURDAY FOLLOWED BY A COLD FRONT SUNDAY OR MONDAY. THE MODELS DIFFER ON THE TIMING OF THE SYSTEM FOR NEXT WEEKEND WITH THE ECMWF BEING SLOWER AND TRACKING THE SURFACE LOW THROUGH MAINE VERSUS THE GFS TRACKING THE LOW NORTH OF THE ST LAWRENCE RIVER. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... SHORT TERM...LIFR AND IFR CONDITIONS WILL CONTINUE INTO THE EARLY AFTERNOON. FZRA AND FZDZ WILL CONTINUE AS WELL. BY THE LATE AFTERNOON NW WINDS WILL BEGIN SLOWLY CLEARING AND DRYING THE AREA OUT FROM W TO E. LONG TERM...EXPECT VFR THROUGH THE PERIOD. && .MARINE... SHORT TERM...MARGINAL SCA CONDITIONS WILL CONTINUE INTO THE EARLY AFTERNOON. WINDS WILL REMAIN MOSTLY BELOW 25 KTS...BUT SEAS WILL REMAIN NEAR 5 FT. CAA OVER THE WATERS TUE COULD BRINGS WINDS AND SEAS BACK TO SCA THRESHOLDS. LONG TERM...SMALL CRAFT CONDITIONS ARE POSSIBLE WEDNESDAY THROUGH FRIDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MEZ007>009. ICE STORM WARNING UNTIL NOON EST TODAY FOR MEZ012>014-019>022- 024>028. FREEZING RAIN ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MEZ018-023. NH...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR NHZ001-002. FREEZING RAIN ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR NHZ004-006-008>010-013-014. FREEZING RAIN ADVISORY UNTIL NOON EST TODAY FOR NHZ003-005-007. MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR ANZ150- 152-154. && $$ LEGRO/HAWLEY
AREA FORECAST DISCUSSION
NWS CARIBOU ME
1240 AM EST MON DEC 23 2013 .SYNOPSIS... WEAK LOW PRESSURE WILL REMAIN OVER THE GULF OF MAINE THROUGH MONDAY. COLD HIGH PRESSURE WILL THEN MOVE IN TUESDAY AND WEDNESDAY. && .NEAR TERM /THROUGH TODAY/... UPDATE 0035 EST: HAVE ADJUSTED TEMPERATURE...NO OTHER CHANGES. THE HRRR CONTINUES TO HAVE A PRETTY GOOD HANDLE ON THE AREAS THAT ARE GETTING PRECIPITATION VERSUS THE AREAS THAT ARE GETTING FREEZING DRIZZLE OR NOTHING AT ALL. THERE IS A VERY STRONG FRONTAL BOUNDARY THAT EXTENDS ACROSS CENTRAL NY STATE INTO CENTRAL MASSACHUSETTS WITH TEMPERATURES NEARLY 30 DEGREES WARMER TO THE SOUTH OF THIS BOUNDARY. THE FRONT WILL REMAIN WELL SOUTH OF OUR AREA TONIGHT....HOWEVER...TEMPS RIGHT ALONG THE IMMEDIATE COAST MAY SLOWLY RISE TO AROUND OR JUST ABOVE FREEZING BY MORNING. PRECIPITATION THAT IS BREAKING OUT DOWN ACROSS VIRGINIA LATE THIS EVENING WILL STREAM TO THE NORTHEAST OVERNIGHT AND SHOULD OVERSPREAD MUCH OF DOWNEAST MAINE BY AROUND 12Z MON MORNING. NO MAJOR CHANGES TO THE ONGOING FORECAST WITH JUST A FEW TWEAKS. THE CONCERN REMAINS THAT WHEN THE STEADY PRECIPITATION MOVES BACK ACROSS DOWNEAST AREAS TOMORROW THAT TEMPERATURES RIGHT ALONG THE COAST WILL BE ABOVE FREEZING AND ICING MAY NOT END UP BEING A MAJOR CONCERN FOR THE IMMEDIATE COASTAL COMMUNITIES. BANGOR AND INLAND AREAS STILL LOOK LIKELY TO SEE ANOTHER ROUND OF FREEZING RAIN TOMORROW. HAVE ADDRESSED THIS IN FREEZING RAIN ADVISORY BY ADVERTISING THE GREATEST CONCERN FOR ICING BEING INLAND. PREVIOUS DISCUSSION... HANCOCK AND WASHINGTON COUNTY HAVE GOTTEN HIT THE HARDEST WITH THE ICE STORM WITH ABOUT ONE HALF INCH ICE ACCRETION. SNOW ACCUMULATIONS OVER THE NORTH HAVE BEEN 4 TO 10 INCHES. IN BETWEEN, IT HAS BEEN A MIX OF SNOW, SLEET, AND FREEZING RAIN WITH GENERALLY SLEET AMOUNTING TO THE MAJORITY OF THE ACCUMULATIONS. SEE OUR PUBLIC INFORMATION STATEMENT FOR MORE TOTALS. THROUGH TONIGHT, BOTTOM LINE IS THAT PRECIPITATION WILL BE QUITE LIGHT, UNTIL ANOTHER ROUND OF PRECIP MOVES IN DOWNEAST ON MONDAY. A DEFINITE BREAK BETWEEN SYSTEMS, AND HAVE OPTED TO DROP ALL THE WARNINGS AND REPLACE IT WITH A WINTER WEATHER ADVISORIES AND FREEZING RAIN ADVISORIES, EFFECTIVE NOW THROUGH LATE MONDAY, FOR ALL BUT THE EXTREME NORTH. LIGHT SLEET, FREEZING DRIZZLE, AND SNIZZLE HAS MADE IT AS FAR NORTH AS ABOUT CARIBOU THIS EVENING BUT WILL RETREAT SOUTH A BIT TONIGHT. GENERALLY, FROM MARS HILL NORTH LOOK FOR AN INCH OR TWO OF MOSTLY SNOW TONIGHT, WITH JUST VERY LIGHT INTERMITTENT PRECIPITATION SOUTH OF MARS HILL FALLING AS FREEZING DRIZZLE OR SLEET. ON MONDAY DURING THE DAY, HOWEVER, HEAVIER PRECIP MOVES BACK IN MAINLY FROM I-95 SOUTH/EAST. FEEL THAT MOST AREAS EXCEPT PERHAPS THE VERY IMMEDIATE COAST WILL STAY JUST BELOW FREEZING, WITH FREEZING RAIN BEING THE PREDOMINANT PRECIP TYPE FOR DOWNEAST WITH UP TO ONE QUARTER INCH ADDITIONAL ICE ACCRETION. INTO CENTRAL AREAS, THE PRECIP WILL BE LIGHTER AND WE ARE LOOKING FOR A MIX OF SNOW, SLEET, AND FREEZING RAIN WITH UP TO ONE TENTH INCH ICE. ADVISORIES TO COVER THIS EVENT RUN THROUGH THE END OF THE DAY MONDAY. FELT MOST MODEL GUIDANCE WAS TOO WARM FOR SURFACE TEMPS FOR MONDAY AND UNDERCUT THEM BY SEVERAL DEGREES. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY/... A WEAK COASTAL SURFACE LOW PRESSURE SYSTEM WILL BE MOVING INTO THE CANADIAN MARITIMES MONDAY EVENING AND BRING TO AN END A PROLONGED PERIOD OF MIXED PRECIPITATION FOR DOWNEAST MAINE. WILL SEE LIGHT SNOW OR SNOW SHOWERS ACROSS NORTHERN MAINE INTO TUESDAY WITH AN INVERTED TROUGH. NORTHWEST WINDS WILL PICK UP ON TUESDAY BEHIND THIS SYSTEM AND MAY CAUSE SOME ISSUES FOR LOCATIONS WITH ICE ON TREES AND STRUCTURES. COLD CANADIAN HIGH PRESSURE BUILDS INTO MAINE FOR CHRISTMAS DAY WITH TEMPERATURES AROUND 15 DEGREES BELOW CLIMATOLOGY. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... THE 12Z ECMWF IS FAR MORE ACTIVE FOR NORTHERN NEW ENGLAND THROUGH NEXT WEEKEND COMPARED THE 12Z GFS. THE ECWMF AMPLIFIES A CLIPPER SYSTEM THURSDAY NIGHT AND EARLY FRIDAY IN A SIMILAR MANNER TO A RECENT STORM ON DECEMBER 17-18. THIS MODEL LATER BRINGS ANOTHER AREA OF SURFACE LOW PRESSURE ON SUNDAY. THE GFS IS NOTICEABLY WEAKER WITH BOTH SYSTEMS. LOADED A BLEND OF THESE MODELS WITH AN EMPHASIS ON THURSDAY NIGHT/FRIDAY AND SUNDAY. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... NEAR TERM: MOSTLY VLIFR TO IFR AT THE TERMINALS THROUGH MONDAY. PRECIPITATION WILL MAINLY BE SNOW OR A MIX OF SNOW AND SLEET NORTH OF KPQI AND FREEZING DRIZZLE AT KBGR AND KBHB. STEADIER FREEZING RAIN WILL DEVELOP AT KBGR MONDAY WITH FREEZING RAIN LIKELY CHANGING TO RAIN AT KBHB. SHORT TERM: IFR CIGS AND VSBYS WILL BE POSSIBLE DUE TO SNOW AND/OR MIXED PRECIPITATION MONDAY NIGHT WITH A DEPARTING WEAK SURFACE LOW PRESSURE SYSTEM. LIFR/IFR CIGS AND VSBYS WILL BE POSSIBLE THURSDAY NIGHT AND FRIDAY DUE TO SNOW AND FOG. && .MARINE... NEAR TERM: SMALL CRAFT CONDITIONS THROUGH ABOUT MIDDAY MONDAY THEN IMPROVING. SEAS THIS EVENING AS OF 9 PM ARE RUNNING AROUND 8 FEET AT THE EASTERN MAINE SHELF WITH A NORTH TO NORTHEAST WIND OF 15 TO 20 KNOTS. SHORT TERM: NO HEADLINES ARE EXPECTED THROUGH THURSDAY. AN SCA OR GALE WATCH MAY BE NEEDED THURSDAY NIGHT AND FRIDAY WITH AN AMPLIFYING CLIPPER SYSTEM. && .EQUIPMENT... SWITCHED THE RADAR TO CLEAR AIR MODE TO BETTER PICK UP THE LIGHTER PRECIPITATION FALLING ACROSS THE AREA. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...FREEZING RAIN ADVISORY UNTIL 6 PM EST THIS EVENING FOR MEZ011- 015>017-029-030-032. WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MEZ003>006-010-031. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EST TODAY FOR ANZ050>052. && $$ NEAR TERM...MIGNONE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
609 PM EST TUE DEC 24 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 438 PM EST TUE DEC 24 2013 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOWS SHRTWV RDG AXIS MOVING INTO THE WRN LKS BTWN DEPARTING TROF IN THE SE GRT LKS RESPONSIBLE FOR LES THE PAST FEW DAYS AND A PAIR OF SHRTWVS DIGGING SEWD THRU SCENTRAL CANADA/THE NRN ROCKIES E OF MEAN RDG NEAR THE W COAST. WITH SFC HI PRES BLDG ACRS THE AREA...LINGERING LES NEAR LK SUP HAS DIMINISHED AND PUSHED INTO THE OPEN WATERS AS THE FLOW IS SHIFTING TO THE SSW IN ADVANCE OF THE SFC LO PRES TROF IN THE NRN PLAINS ASSOCIATED WITH THE TWO CLIPPER SHRTWVS. THE 12Z INL/MPX RAOBS SHOWED A VERY DRY AIRMASS WITH PWATS UNDER 0.10 INCH...SO SKIES ARE TURNING MOSUNNY AT MOST PLACES AS THE SSW FLOW SHIFTS LINGERING LO CLDS BACK OUT OVER LK SUP. MID CLDS IN ADVANCE OF APRCHG CLIPPER SHRTWVS/SFC TROF ARE PUSHING EWD THRU MN...WITH SN FALLING OVER NW MN AND THE ERN DAKOTAS. ALTHOUGH THIS SN HAS BEEN MDT AT SOME PLACES UNDER THE SHARPER H85-5 QVECTOR CVNGC...THE COVERAGE APPEARS TO BE LIMITED BY ABSENCE OF SGNFT MSTR INFLOW. MAIN FCST CONCERNS IN THE SHORT TERM ARE EXPECTED POPS/SN AMOUNTS LATE TNGT AND XMAS MRNG ASSOCIATED WITH UPSTREAM CLIPPER SHRTWVS AND GOING WINTER STORM WATCH OVER THE ERN CWA/NEED FOR ANY NEW HEADLINES. TNGT INTO XMAS DAY...UPR TROF TO THE NW IS FCST TO SHIFT TO THE SE AND STRETCH FM NW ONTARIO THRU MN AND INTO THE CENTRAL PLAINS BY 12Z WED. MODELS SHOW PCPN IN ADVANCE OF THIS TROF ARRIVING OVER THE WRN CWA LATE THIS EVNG AND PUSHING TO THE E...WITH A 6-9 PERIOD OF SN AT MOST LOCATIONS BEFORE THE SN DIMINISHES OVER THE W 09-12Z WED AND BY ABOUT 18Z WED OVER THE ERN CWA FOLLOWING DEPARTURE OF DEEP LYR QVECTOR CNVGC. MAIN NEGATIVES FOR SGNFT SN FALL INCLUDE FCST SHARPER H85-5 QVECTOR CNVGC/SHARPER H7 UVV ASSOCIATED WITH INCOMING OUT OF PHASE SHRTWVS FOCUSING TO THE S OF UPR MI... LACK OF SGNFT MSTR INFLOW WITH ONLY ABOUT 1.5-2 G/KG SPECIFIC HUMIDITY NEAR H7...AND LIMITED RESIDENCE OF TIME OF PCPN. ONE FACTOR IN FAVOR OF SOMEWHAT HIER SN AMOUNTS IS FCST DEEP DGZ THAT MAY BOOST SN/WATER RATIOS AS HI AS 20-25:1. CONSIDERING MODEL QPF 0.05-0.15 INCH...EXPECT 1 TO 3 INCHES OF SN. THE ONE EXCEPTION WL BE OVER THE ERN CWA DOWNWIND OF LK MI...WHERE INCRSG SSW FLOW UP THE LENGTH OF LK MI IN THE PRESENCE OF DEEP MSTR/H85 TEMPS ARND -15C WL BRING A PERIOD OF HEAVIER LK ENHANCED SN. PRESENCE OF LINGERING BAND IN NRN LK MI AS SHOWN ON RECENT STLT IMAGERY EARLY THIS AFTN INCREASES CONFIDENCE IN THIS FCST. BULK OF HIER RES MODELS SHOW THE HEAVIER LES BAND IMPACTING FAR SE SCHOOLCRAFT COUNTY/SRN LUCE COUNTY IN THE 09Z-15Z WED TIME FRAME. WITH MODEL QPF RANGING FM 0.25 INCH TO AS MUCH AS 0.40 INCH AND DEEP DGZ SHOWN ON THE FCST SDNGS...EXPECT AT LEAST A HI END ADVY SNFALL IN THIS AREA. FCST SDNGS ALSO SHOW A PERIOD OF NEARLY UNIDIRECTIONAL SSW FLOW WITHIN THE MIXED LYR FOR A FEW HRS DURING TIME OF PEAK SN INTENSITY. GIVEN THESE FVRBL CONDITIONS...OPTED TO UPGRADE WATCH TO A WRNG FOR LUCE COUNTY...WHERE HEAVIER LES BAND IS MOST LIKELY TO RESIDE THE LONGEST AND DROP UP TO 9 TO PERHAPS 10 INCHES ALONG M-28 E OF ERY. WENT WITH AN ADVY FOR SCHOOLCRAFT COUNTY WITH POTENTIAL FOR SOME LK ENHANCEMENT...ESPECIALLY E OF SENEY AND MANISTIQUE. AS FOR TEMPS...ARRIVAL OF THICKER CLDS/STEADY S WIND WL ALLOW FOR ONLY A RELATIVELY SMALL TEMP DIP EARLY OVER THE W HALF. BUT TO THE E...EXPECT TEMPS TO FALL QUICKLY OVER THE INTERIOR ERN CWA THIS EVNG BEFORE THE CLDS AND STEADY S WINDS ARRIVE LATER. LATER ON XMAS DAY...AS THE UPR TROF AND SFC REFLECTION SHIFT SLOWLY THRU THE UPR GREAT LKS...THE LLVL FLOW IS PROGGED TO VEER TOWARD THE W. THIS WSHFT TO A MORE WSW DIRECTION WL END THE THREAT OF LK ENHANCED SHSN OVER THE E BY EARLY AFTN BUT CAUSE SOME LES TO DVLP OVER THE W IN THE AFTN AS H85 TEMPS DIP BACK NEAR -18C BY 00Z THU. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 438 PM EST TUE DEC 24 2013 WEDNESDAY NIGHT...LOW LEVEL CONV ALONG A COLD FRONT AND 850 MB TEMPS DROPPING FROM -15C TO -19C WILL BRING AN INCREASE IN LES INTO NORTHWEST UPPER MICHIGAN WED EVENING AND OVER ERN CWA OVERNIGHT. EVEN WITH A FAVORABLE PLACEMENT OF THE DGZ IN THE CONVECTIVE LAYER GIVING SLR VALUES NEAR 25/1...INVERSION HEIGHTS NEAR 6K FT AND STEADILY VEERING WINDS SHOULD KEEP ACCUMULATIONS IN THE 2 TO 4 INCH RANGE...WITH THE GREATEST AMOUNTS IN THE HIGHER TERRAIN FROM CALUMET TO TWIN LAKES AND NORTH OF M-28 EAST OF MUNISING. THU INTO THU NIGHT...NW FLOW LES WILL GRADUALLY DIMINISH AS A WEAK SFC RIDGE BUILDS FROM THE UPPER MS VALLEY INTO THE WRN LAKES BRINGING BACKING WINDS AND LOWERING INVERSION HEIGHTS. THE STRONGEST FORCING AND MOST FAVORABLE WAA/ISENTROPIC LIFT ASSOCIATED WITH A WEAK CLIPPER SHORTWAVE TROUGH IS EXPECTED TO REMAIN SOUTH OF THE UPPER MICHIGAN. FRI...THE ECMWF WAS MORE AGGRESSIVE WITH POTENTIAL FOR SOME LIGHT SNOW BY LATE FRI WITH THE WAA/ISENTROPIC LIFT PATTERN DEVELOPING AHEAD OF THE NEXT CLIPPER SHRTWV AND SFC LOW MOVING TOWARD NW ONTARIO COMPARED TO THE GFS/GEM. WITH LOW CONFIDENCE IN ANY PCPN...ONLY SLIGHT/CHANCE POPS WERE INCLUDED...MAINLY OVER THE EAST. SAT INTO SAT NIGHT...A BRIEF WARMUP IS EXPECTED SATURDAY AS UPPER MI WILL BE IN THE WARMER SECTOR AHEAD OF THE NEXT LOW. TEMPS SHOULD CLIMB ABOVE NORMAL WITH HIGHS AROUND 30. MODEL DIFFERENCES WERE EVEN GREATER BY SATURDAY NIGHT...AS THE ECMWF WAS SLOWER/DEEPER WITH SHRTWV AND SFC LOW MOVING THROUGH THE NRN GREAT LAKES. REGARDLESS OF MODEL DIFFERENCES...A COLD FRONT MOVING THROUGH WITH WINDS VEERING SHARPLY TO THE NNW SHOULD BRING LES OR LAKE ENHANCED SNOW INTO NRN UPPER SAT NIGHT. SUN-TUE...ANOTHER VERY COLD ARCTIC AIRMASS WILL DOMINATE THE REGION THROUGH THE PERIOD WITH LES EXPECTED FOR NW WIND FAVORED SNOWBELTS. WIND CHILL VALUES NEAR ADVISORY WILL BE POSSIBLE OVER THE WEST HALF BOTH EARLY MONDAY AND TUESDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 608 PM EST TUE DEC 24 2013 AS THE PRES GRADIENT OVER UPR MI TIGHTENS BTWN A DEPARTING SFC HI PRES RDG AND AN APRCHG LO PRES TROF...EXPECT GUSTY S WINDS TO DVLP THIS EVENING AT THE MORE EXPOSED IWD/SAW LOCATIONS. VFR CONDITIONS WL GIVE WAY TO IFR CONDITIONS BY LATE EVNG AS SN IN ADVANCE OF THE TROF MOVES W-E INTO UPR MI. EVEN AFTER THE SN DIMINISHES W-E BY SUNRISE ON WED...MVFR SC CIGS WL LINGER. AS THE WEAKER FLOW VEERS TOWARD THE W LATER ON WED MRNG...MORE SHSN/IFR VSBYS MAY IMPACT CMX LATE IN THE TAF PERIOD. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 438 PM EST TUE DEC 24 2013 AS THE PRES GRADIENT TIGHTENS OVER LAKE SUPERIOR THIS EVENING BETWEEN DEPARTING SURFACE HI PRES RIDGE AND AN APPROACHING LO PRES TROF...OPTED TO MAINTAIN GOING GALE WARNING FOR THE ECENTRAL PORTIONS OF THE LAKE. AWAY FROM THIS FAVORED AREA...SOME GALE FORCE GUSTS WILL BE POSSIBLE. CLOSER APPROACH AND THEN PASSAGE OF LO PRES TROF AND WEAKER GRADIENT ON WED WILL CAUSE THE GALES TO DIMINISH AS THE WINDS VEER TOWARD THE W-NW. NORTHWEST TO NORTH GALES WILL AGAIN BE POSSIBLE SATURDAY NIGHT BEHIND AN ARCTIC COLD FRONT. HEAVY FREEZING SPRAY IS ALSO EXPECTED INTO EARLY NEXT WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 1 AM TO 10 AM EST WEDNESDAY FOR MIZ014-085. WINTER STORM WARNING FROM 1 AM TO 1 PM EST WEDNESDAY FOR MIZ007. LAKE SUPERIOR... GALE WARNING FROM 11 PM THIS EVENING TO 7 AM EST WEDNESDAY FOR LSZ266. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...JLB AVIATION...07 MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
345 PM EST MON DEC 23 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 343 PM EST MON DEC 23 2013 LATEST WV SATELLITE IMAGERY AND RUC ANALYSIS SHOWS BROAD 5H TROUGH SLOWLY PUSHING E ACROSS THE WRN GREAT LAKES THIS AFTERNOON. WEAK 850-500MB Q-VECTOR CONVERGENCE ASSOC WITH THIS TROUGH OVER LAKE SUPERIOR WILL TRANSITION TO Q-VECTOR DIVERGENCE THIS EVENING. VIS IMAGERY SHOWS NE WIND PARALLEL LAKE EFFECT SNOW BANDS ACROSS LAKE SUPERIOR IMPACTING MAINLY FAR WESTERN AND NORTH CENTRAL UPPER MI. A FEW OF THE MORE INTENSE BANDS HAVE PRODUCED PERIODS OF MODERATE SNOW. LES HAS BEEN VERY FLUFFY WITH SNOW RATIOS 40-50/1. MAIN FORECAST CONCERN IS CONTINUING LES EVENT FOR FAR WESTERN AND NORTH CENTRAL COUNTIES INTO THIS EVENING AND THEN DIMINISHING LES OVERNIGHT INTO TUE MORNING. EXPECT ADDITIONAL SNOWFALL AMOUNTS OF 2 TO 5 INCHES THROUGH THIS EVENING. BEST LOW-LVL CONVERGENCE SUGGESTS MORE INTENSE LES BANDS AND THUS GREATEST SNOW AMOUNTS WILL BE OVER ERN HALF OF MQT COUNTY INTO PERHAPS WRN ALGER COUNTY. GIVEN EXPECTATION OF CONTINUING LES ACCUMULATION INTO AT LEAST THE EVENING HRS WILL CONTINUE ADVISORIES FOR GOGEBIC-ONTONAGON AND MQT-BARAGA INTO THE EARLY OVERNIGHT. LES SHOULD GENERALLY BE WINDING DOWN BY LATE EVENING INTO OVERNIGHT HRS WITH Q-VECT DIVERGENCE ACROSS THE AREA AND WEAKENING WIND FIELDS. LOW-LVL CONVERGENCE MAY STRENGTHEN DUE TO WEAKENING WINDS AND DEVELOPING LAND BREEZES TO ALLOW MORE LOCALLY INTENSE LES BANDS TO FORM AND PERHAPS EVEN A MESOLOW OR TWO OFF THE PORCUPINE MOUNTAINS AND OVER MQT BAY AS DEPICTED BY LOCAL AND REGIONAL MESOSCALE MODELS. HOWEVER...WINDS BACKING TO THE WEST/SOUTHWEST OVERNIGHT AHEAD OF ADVANCING SFC RDG AXIS SHOULD KEEP LES BANDS OR MESOLOW FEATURES MOVING ENOUGH EASTWARD TO EFFECTIVELY LIMIT ACCUMULATIONS FOR THE OVERNIGHT HRS. DECREASING CLOUD COVER OVERNIGHT AND LIGHT WINDS WILL ALLOW TEMPERATURES TO FALL OFF OUTSIDE OF THOSE AREAS WHERE THE LAKE EFFECT SNOWS LINGER. COLDEST TEMPERATURES ARE EXPECTED OVER THE FAR EAST AND INTERIOR WEST SECTIONS. THE WRN INTERIOR ALONG THE WI BDR WITH LIKELY SEE A FEW LOCATIONS PLUMMET TO 10 BELOW OR COLDER WHERE TYPICAL COLD SPOTS OVER LUCE COUNTY COULD ALSO DIP NEAR 10 BELOW ZERO. GENERALLY FOLLOWED A BLEND OF THE BETTER PERFORMING CANADIAN REGIONAL GEM AND ECMWF FOR MIN TEMPS. TUESDAY...DECENT MODEL AGREEMENT THAT LINGERING LAKE EFFECT OVER NCNTRL CWA WILL BE PUSHED OUT OVR SOUTH CENTRAL LK SUPERIOR THROUGH THE MORNING AS WINDS BECOME SSW AHEAD OF APPROACHING SHORTWAVE AND SFC TROUGH OVER THE NRN PLAINS. MAY BE ABLE TO SNEAK IN SOME SUNSHINE OVER MUCH OF THE CWA INTO EARLY AFTN BEFORE HIGH CLOUDS START INCREASING AHEAD OF SHORTWAVE TROUGH DROPPING ACROSS THE NORTHERN PLAINS. WARM ADVECTION SSW FLOW WILL ALLOW FOR MAX TEMPS TO REBOUND INTO THE TEENS ACROSS MUCH OF THE AREA. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 310 PM EST MON DEC 23 2013 UPPER AIR PATTERN WILL CONSIST OF A 500 MB RIDGE ON THE WEST COAST AND A TROUGH OVER THE NORTHERN PLAINS 00Z WED. NAM ALSO SHOWS A CLOSED 500 MB LOW OVER NORTHERN ALBERTA 00Z WED. BOTH THE LOW AND THE TROUGH MOVE TO THE EAST WITH THE REMAINS OF THE LOW HELPING TO DIG A DEEP UPPER TROUGH INTO THE UPPER GREAT LAKES ON WED. NAM SHOWS SOME 850-500 MB Q-VECTOR CONVERGENCE OVER THE CWA WITH DEEPER MOISTURE TUE NIGHT LASTING INTO WED BEFORE BOTH MOVE OUT WED NIGHT INTO THU. GFS AND ECMWF SHOW ABOUT THE SAME THING. DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST. CLIPPER TYPE SYSTEM COMES IN FOR TUE NIGHT INTO WED AND WILL HAVE SOME LAKE MICHIGAN LAKE ENHANCEMENT OVER THE ERN CWA WHICH WAS ALREADY COVERED IN THE PREVIOUS FORECAST. COULD SEE UP TO 8 INCHES IN ERN SCHOOLCRAFT AND LUCE COUNTIES FOR TUE NIGHT AND WED. DID LOWER TEMPERATURES A BIT THOUGH EACH DAY FOR LOWS AND HIGHS TUE NIGHT THROUGH THU AS THE TEMPERATURES SEEMED A BIT TOO WARM CONSIDERING THE PERSISTENT COLD PATTERN WE HAVE BEEN IN. IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB TROUGH OVER THE CENTRAL U.S. 12Z FRI WITH A RIDGE OVER THE WESTERN U.S. UPPER FLOW BECOMES MORE ZONAL OVER THE NORTHERN PLAINS AND UPPER GREAT LAKES 12Z SAT WHICH WILL MEAN A BRIEF WARMING TREND IS STARTING. A BROAD 500 MB TROUGH THEN MOVES INTO THE UPPER GREAT LAKES 12Z SUN AND INTO MONDAY WITH COLD AIR ONCE AGAIN OVER THE AREA WITH THE DEEP UPPER TROUGH. LAKE EFFECT SNOW WILL BE THE MAIN RULE FOR MOST OF THIS FORECAST PERIOD WITH TEMPERATURES GOING BACK BELOW NORMAL SUNDAY INTO MONDAY. CLIPPER SYSTEM MOVES THROUGH FOR SAT AND THIS WOULD BE THE WARMEST DAY OF THE WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1240 PM EST MON DEC 23 2013 KIWD...NE WINDS WILL BACK MORE NNE LATER THIS AFTERNOON WHICH SHOULD FINALLY ALLOW SOME HEAVIER LES BANDS TO MOVE INTO THE AREA. EXPECT CONDITIONS TO LOWER FROM VFR TO IFR BY LATE AFTERNOON WITH THE HEAVIER LES BANDS AND THEN IMPROVE TO VFR AFT 06Z TONIGHT AS WINDS BACK MORE TO THE SW. KCMX...MVFR CONDITIONS IN NE FLOW LES WILL CONTINUE THROUGH TONIGHT. EXPECT IMPROVEMENT TO VFR BY LATE TUE MORNING AS WINDS BECOME SW. KSAW...EXPECT IFR CONDITIONS IN NNE FLOW LES TO IMPROVE TO MVFR THIS EVENING AS FLOW WEAKENS AND BACK MORE NNW THIS EVENING. CONDITIONS WILL IMPROVE TO VFR LATE TONIGHT AS WINDS BECOME WEST AND THEN BACK SW BY LATE TUE MORNING. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 343 PM EST MON DEC 23 2013 NORTHEAST WINDS WILL GRADUALLY DIMINISH THROUGH THE DAY. HEAVY FREEZING SPRAY WILL REMAIN A PROBLEM OVER THE WEST AND NORTH CENTRAL PORTIONS OF LAKE SUPERIOR UNTIL THE PRESSURE GRADIENT RELAXES A BIT MORE IN THE AFTERNOON. AFTER A BRIEF RESPITE...SOUTH WINDS PICK UP AGAIN AHEAD OF THE NEXT SYSTEM MOVING THROUGH TO THE NORTH OF LAKE SUPERIOR TUESDAY NIGHT WITH GALE FORCE WINDS TO 35 KNOTS EXPECTED THEN...MAINLY FOR THE EASTERN PORTION OF THE LAKE. WINDS DIMINISH WEDNESDAY AND REMAIN BELOW 20 KNOTS THROUGH FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 3 AM EST TUESDAY FOR MIZ004-005. LAKE EFFECT SNOW ADVISORY UNTIL MIDNIGHT EST /11 PM CST/ TONIGHT FOR MIZ002-009. LAKE SUPERIOR... GALE WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY MORNING FOR LSZ266. HEAVY FREEZING SPRAY WARNING UNTIL 6 PM EST /5 PM CST/ THIS EVENING FOR LSZ162-263-264. LAKE MICHIGAN... NONE. && $$ SHORT TERM...VOSS LONG TERM...07 AVIATION...VOSS MARINE...VOSS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1244 PM EST MON DEC 23 2013 LATEST UPDATE... AVIATION .SYNOPSIS... ISSUED AT 330 AM EST MON DEC 23 2013 SNOW SHOWERS ARE EXPECTED TO BE ON THE INCREASE TODAY...ESPECIALLY FOR AREAS ACROSS THE SOUTHWEST CORNER OF LOWER MICHIGAN. THE SNOW SHOWERS ARE EXPECTED TO BECOME LOCALLY HEAVY AND COULD BRING A FEW INCHES OF SNOW TO SOME LOCAL AREAS. THE SNOW SHOWERS WILL CONTINUE INTO THE EVENING HOURS BEFORE MOVING SOUTH AND WEST OF THE AREA TOWARD DAYBREAK TUESDAY MORNING. COLDER AIR WILL MOVE IN FOR TUESDAY ALONG WITH SOME POSSIBLE SUNSHINE FOR A SHORT PERIOD OF TIME. THE AREA WILL SEE A COUPLE OF WAVES OF LOW PRESSURE THEN MOVE IN FOR CHRISTMAS DAY AND ON THURSDAY. THIS WILL BRING MORE SNOW ACCUMULATIONS TO THE AREA...ESPECIALLY FOR AREAS NEAR THE LAKESHORE. && .UPDATE... ISSUED AT 1018 AM EST MON DEC 23 2013 WILL BE EXPANDING THE ADVISORY TO INCLUDE MUSKEGON AND KENT COUNTIES. THE THREAT FOR HEAVY SNOW HAS DECREASED SOMEWHAT OVER VAN BUREN AND KALAMAZOO...BUT WILL KEEP THEM IN THE ADVISORY. RADAR INDICATES THE BEGINNINGS OF A DOMINANT SNOW BAND EXTENDING SOUTHEAST THROUGH THE HOLLAND AREA. THIS IS CONSIDERABLY FARTHER NORTH THAN PREVIOUS THINKING. RADAR RETURNS ARE STARTING TO SPREAD TO THE NORTHWEST OVER LAKE MICHIGAN...SUGGESTING THAT THE DEPTH OF THE BAND IS INCREASING WITH INVERSION HEIGHTS AHEAD OF THE UPPER TROUGH APPROACHING FROM THE MIDWEST. THIS BAND IS EXPECTED TO INTENSIFY AND WILL LIKELY UNDULATE. RADAR ALREADY SUGGESTS A MESOLOW TRYING TO FORM WEST OF MUSKEGON. A CONSENSUS OF SIMULATED REFLECTIVITY IN THE HIGH RESOLUTION MODELS SUGGESTS THAT THE BAND WILL LIFT NORTH TOWARDS MUSKEGON AND KENT COUNTY DURING THE COURSE OF THE DAY. A PARTICULARLY INTERESTING TIME FRAME WILL BE EARLY TONIGHT WHEN THE HRRR AND DOWNSCALED NAM BRING A PRONOUNCED MESOLOW ACROSS MUSKEGON AND KENT COUNTIES WITH A LIKELY ENHANCED BURST OF SNOW. && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 330 AM EST MON DEC 23 2013 THE MAIN CONCERN IN THE SHORT TERM IS THE POTENTIAL LOCALLY HEAVY SNOW BAND THAT LOOKS LIKELY TO AFFECT THE SOUTHWEST CORNER OF THE CWFA TODAY AND TONIGHT. WE WILL BE EXPANDING THE ADVISORY IN COVERAGE TO INCLUDE OTTAWA AND BARRY COUNTIES. WE WILL ALSO BE EXTENDING THE ADVISORY IN TIME TO GO THROUGH 12Z TUE. WE ARE CONCERNED THAT MUSKEGON AND KENT COUNTIES MAY NEED TO BE INCLUDED IN THE ADVISORY ALSO...HOWEVER WE ARE NOT QUITE CONFIDENT YET TO INCLUDE THEM IN AT THIS TIME DUE TO UNCERTAINTY WITH THE MOVEMENT OF THE NARROW BAND. SNOW SHOWERS HAVE STARTED TO AFFECT THE SW CORNER OF THE CWFA ALREADY THIS MORNING. THE SNOW SHOWERS ARE RESULTING FROM COLDER AIR COMING ON THE NW FLOW IN PLACE. THIS NW FLOW IS ON THE SRN PERIPHERY OF A LARGER SCALE SFC TROUGH THAT CURRENTLY IS ORIENTED FROM THE STORM SYSTEM ACROSS THE NE U.S. ALL THE WAY TO MANITOBA. THE TROUGH IS RESULTING FROM BOTH THE UPPER WAVE DIVING SE TOWARD THE AREA... AND A CONTRIBUTION FROM THE GREAT LAKES. WE EXPECT THE SNOW SHOWERS TO INTENSIFY DURING THE DAY TODAY. THE SHORTWAVE DIVING IN FROM THE NW WILL HELP TO INCREASE INVERSION HTS TO OVER 10K FEET AND CAUSE THE SFC TROUGH TO SHARPEN UP. THIS WILL ENHANCE THE CONVERGENCE OVER PLENTY OF OVER LAKE INSTABILITY WITH DELTA T/S SITTING AROUND THE MID TO UPPER TEENS. ANOTHER FACTOR FOR HEAVIER SNOW AMOUNTS IS THE BEST CONVERGENCE OCCURS IN THE FAVORED LAYER OF THE DGZ AROUND 2-4K FT ALOFT. WE EXPECT TO SEE SNOW SHOWERS TO BECOME HEAVY ENOUGH TO SEE LOCAL SNOWFALL RATES OF OVER AN INCH PER HOUR UNDER THE NARROW BAND. WE EXPECT THE BAND TO GRADUALLY SHIFT NORTH THIS AFTERNOON RESULTING FROM THE UPPER FLOW AHEAD OF THE WAVE. THE FLOW WILL SHIFT FROM THE NW ORIENTATION TO A MORE WNW ORIENTATION. THIS WILL SHIFT THE HEAVIEST SNOW BAND FROM THE CURRENT LOCATION TO AT LEAST A HOLLAND TO HASTINGS CORRIDOR. SOME OF THE HIGHER RES MODELS ARE EVEN SHOWING THE BAND GETTING INTO A GRAND HAVEN TO SRN KENT COUNTY LINE...AND EVEN SOME ARE TAKING THIS TO A MUSKEGON TO GR LINE. THESE BANDS ARE QUITE TRICKY TO NAIL DOWN...BUT WHERE THEY GO CAN CAUSE QUITE AN IMPACT IN A SHORT TIME. OUR CONFIDENCE IS HIGH ENOUGH AT THIS TIME TO ADD IN OTTAWA AND BARRY COUNTIES FOR NOW. THERE IS SOME TIME TO WATCH THE EVOLUTION OF THE BAND AND EXPAND THE ADVISORY FURTHER NORTH INTO KENT AND MUSKEGON COUNTIES IF NEEDED AS IT WOULD NOT AFFECT THOSE AREAS UNTIL AT LEAST 21Z OR SO. THE BAND WILL END UP AT ITS FARTHEST NORTH ORIENTATION BETWEEN 00-03Z BEFORE IT THEN SINKS BACK SOUTH AND THEN EXITS THE AREA TOWARD 12Z TUE. THIS WILL OCCUR AS THE UPPER WAVE PASSES EAST OF THE AREA TOWARD 12Z TUE. WE CAN NOT RULE OUT AMOUNTS REACHING WARNING CRITERIA AT LOCATIONS THAT SEE THE BANDS LAST OVER A CERTAIN AREA THE LONGEST LIKE ALLEGAN COUNTY AND NEAR HOLLAND. WE WILL STICK WITH THE ADVISORY AND WATCH HOW SNOWFALL TRANSPIRES. MOST OF THE SNOW SHOWERS SHOULD TRANSITION OFFSHORE BY TUE MORNING AS THE FLOW BECOMES NNE BEHIND THE TROUGH PASSAGE. WE ACTUALLY EXPECT AT LEAST SOME CLEARING WHICH WOULD ALLOW TEMPS TO FALL OFF QUITE COLD AT INLAND LOCATIONS. WE COULD SEE SOME BELOW ZERO READINGS UP TOWARD LEOTA IF SKIES CLEAR ENOUGH. SOME SUN WILL BE FOUND ON TUE WITH THE SFC RIDGE MOVING OVERHEAD AND STRONG SUBSIDENCE BUILDING IN BETWEEN THE TWO UPPER WAVES. SOME LIGHT SNOW SHOWERS MAY MOVE INLAND ON TUE AS THE LOW LEVEL FLOW BECOMES WRLY WITH THE RIDGE. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 330 AM EST MON DEC 23 2013 MORE ACCUMULATING LAKE EFFECT/ENHANCED SNOW IS EXPECTED STARTING LATE CHRISTMAS EVE AND CONTINUING CHRISTMAS DAY AND THURSDAY. THIS IS FUELED BY A SERIES OF SHORTWAVES ASSOCIATED WITH A 120 KT UPPER LEVEL JET DIVING SE FROM WRN CANADA. TOTAL NEW SNOWFALL DURING THIS 48 HOUR PERIOD COULD EASILY EXCEED SIX INCHES WEST OF A CADILLAC TO KALAMAZOO LINE. THE FIRST BATCH OF SNOW FOR LATE CHRISTMAS EVE INTO CHRISTMAS MORNING IS A COMBINATION OF WARM ADVECTION SNOW WITH SSW FLOW LAKE ENHANCEMENT. SEVERAL INCHES OF ACCUMULATION ARE POSSIBLE ALONG THE LK MI COAST NORTH OF HOLLAND DURING THIS TIME. THEN A FAIRLY POTENT SHORTWAVE FOLLOWS IMMEDIATELY BEHIND THIS STARTING LATE CHRISTMAS DAY AND LASTING INTO THURSDAY. MEAN FLOW DURING THIS PERIOD IS WESTERLY BRINGING ADDITIONAL ACCUMULATIONS ALONG AND WEST OF HIGHWAY 131. MORE LAKE EFFECT SNOW SHOWERS ARE POSSIBLE THURSDAY NIGHT AND FRIDAY AS A FINAL NRN STREAM SHORTWAVE COMES THROUGH BEFORE THE UPPER FLOW GOES BRIEFLY ZONAL. SATURDAY CONTINUES TO LOOK LIKE A MILDER DAY AS H8 TEMPS ABOVE ZERO ARRIVE FROM THE WEST AS A LOW MOVES EAST ACROSS LK SUPERIOR. THE WARM UP SHOULD BE RATHER BRIEF HOWEVER AS MODELS SHOW MORE -20C H8 AIR SWEEPING IN ON SUNDAY OR SUNDAY NIGHT. THIS OUGHT TO GET THE LAKE EFFECT CRANKED UP AGAIN. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1244 PM EST MON DEC 23 2013 THE MAIN FOCUS WILL CONTINUE ON A NARROW BAND OF HEAVY LAKE EFFECT SNOW THIS AFTERNOON AND TONIGHT. ENHANCEMENT BEGINNING IN THE WESTERN COUNTIES AS A WAVE OF ENERGY MOVES INTO THE AREA. THE CONVERGENCE BAND IS SLOWLY DRIFTING NORTH WITH ORIENTATION BECOMING MORE EAST-WEST. CONFIDENCE INCREASING FOR THE BAND TO EFFECT MKG TO LANSING WITH SEVERAL HOURS OF MODERATE TO HEAVY SNOW AND IFR/LIFR VISIBILITIES MAINLY WEST OF LANSING. THE WEST-EAST ORIENTED BAND SHOULD MOVE SOUTHWARD AFTER 06Z TONIGHT AND BEGIN IMPACTING AZO/BTL/JXN WHILE SNOW DIMINISHES AT MKG/GRR/LAN. OUTSIDE OF THE POTENTIAL INTENSE BAND OF SNOW THROUGH TONIGHT... MVFR SHOULD BE THE PREDOMINATE FLIGHT CATEGORY WITH CIGS 1500-2500 FEET AND SCATTERED/OCNL LIGHT SNOW REDUCING VSBYS TO 3-5 MILES. && .MARINE... ISSUED AT 419 AM EST MON DEC 23 2013 WE HAVE ISSUED A SMALL CRAFT ADVISORY FOR THE SOUTHERN TWO MARINE ZONES. WEST TO NORTHWEST WINDS WILL COME UP ENOUGH TODAY TO REQUIRE A HEADLINE. THE NEXT HEADLINE WILL COME ON TUESDAY NIGHT AND INTO CHRISTMAS DAY. A SOLID SMALL CRAFT ADVISORY AND POSSIBLE GALE WILL OCCUR AHEAD OF THE CLIPPER SYSTEM EXPECTED TO MOVE IN AT THAT TIME. && .HYDROLOGY... ISSUED AT 857 AM EST MON DEC 23 2013 ARCTIC AIR RETURNS TODAY AND RIVERS ARE EXPECTED TO LOCK BACK IN PLACE WITH ICE OVER THE NEXT FEW DAYS. THIS SHOULD SERVE TO STABILIZE LEVELS. RELATIVELY FLAT ICE ON RIVERS IS A SIGN WATER IS FLOWING RELATIVELY SMOOTHLY BENEATH. TEMPERATURES WILL REMAIN BELOW FREEZING...AND WILL RESULT IN CONTINUED ICE GROWTH ON RIVERS IN SOUTHWEST LOWER MICHIGAN. UNDER THESE CONDITIONS THE THREAT FOR ICE JAMS IS LOW. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR MIZ056-064- 071-072. WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR MIZ050-057- 065. LM...SMALL CRAFT ADVISORY UNTIL 1 PM EST TUESDAY FOR LMZ844-845. && $$ UPDATE...TJT SYNOPSIS...NJJ SHORT TERM...NJJ LONG TERM...MEADE AVIATION...63 HYDROLOGY...WALTON MARINE...NJJ
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1019 AM EST MON DEC 23 2013 LATEST UPDATE... UPDATE .SYNOPSIS... ISSUED AT 330 AM EST MON DEC 23 2013 SNOW SHOWERS ARE EXPECTED TO BE ON THE INCREASE TODAY...ESPECIALLY FOR AREAS ACROSS THE SOUTHWEST CORNER OF LOWER MICHIGAN. THE SNOW SHOWERS ARE EXPECTED TO BECOME LOCALLY HEAVY AND COULD BRING A FEW INCHES OF SNOW TO SOME LOCAL AREAS. THE SNOW SHOWERS WILL CONTINUE INTO THE EVENING HOURS BEFORE MOVING SOUTH AND WEST OF THE AREA TOWARD DAYBREAK TUESDAY MORNING. COLDER AIR WILL MOVE IN FOR TUESDAY ALONG WITH SOME POSSIBLE SUNSHINE FOR A SHORT PERIOD OF TIME. THE AREA WILL SEE A COUPLE OF WAVES OF LOW PRESSURE THEN MOVE IN FOR CHRISTMAS DAY AND ON THURSDAY. THIS WILL BRING MORE SNOW ACCUMULATIONS TO THE AREA...ESPECIALLY FOR AREAS NEAR THE LAKESHORE. && .UPDATE... ISSUED AT 1018 AM EST MON DEC 23 2013 WILL BE EXPANDING THE ADVISORY TO INCLUDE MUSKEGON AND KENT COUNTIES. THE THREAT FOR HEAVY SNOW HAS DECREASED SOMEWHAT OVER VAN BUREN AND KALAMAZOO...BUT WILL KEEP THEM IN THE ADVISORY. RADAR INDICATES THE BEGINNINGS OF A DOMINANT SNOW BAND EXTENDING SOUTHEAST THROUGH THE HOLLAND AREA. THIS IS CONSIDERABLY FARTHER NORTH THAN PREVIOUS THINKING. RADAR RETURNS ARE STARTING TO SPREAD TO THE NORTHWEST OVER LAKE MICHIGAN...SUGGESTING THAT THE DEPTH OF THE BAND IS INCREASING WITH INVERSION HEIGHTS AHEAD OF THE UPPER TROUGH APPROACHING FROM THE MIDWEST. THIS BAND IS EXPECTED TO INTENSIFY AND WILL LIKELY UNDULATE. RADAR ALREADY SUGGESTS A MESOLOW TRYING TO FORM WEST OF MUSKEGON. A CONSENSUS OF SIMULATED REFLECTIVITY IN THE HIGH RESOLUTION MODELS SUGGESTS THAT THE BAND WILL LIFT NORTH TOWARDS MUSKEGON AND KENT COUNTY DURING THE COURSE OF THE DAY. A PARTICULARLY INTERESTING TIME FRAME WILL BE EARLY TONIGHT WHEN THE HRRR AND DOWNSCALED NAM BRING A PRONOUNCED MESOLOW ACROSS MUSKEGON AND KENT COUNTIES WITH A LIKELY ENHANCED BURST OF SNOW. && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 330 AM EST MON DEC 23 2013 THE MAIN CONCERN IN THE SHORT TERM IS THE POTENTIAL LOCALLY HEAVY SNOW BAND THAT LOOKS LIKELY TO AFFECT THE SOUTHWEST CORNER OF THE CWFA TODAY AND TONIGHT. WE WILL BE EXPANDING THE ADVISORY IN COVERAGE TO INCLUDE OTTAWA AND BARRY COUNTIES. WE WILL ALSO BE EXTENDING THE ADVISORY IN TIME TO GO THROUGH 12Z TUE. WE ARE CONCERNED THAT MUSKEGON AND KENT COUNTIES MAY NEED TO BE INCLUDED IN THE ADVISORY ALSO...HOWEVER WE ARE NOT QUITE CONFIDENT YET TO INCLUDE THEM IN AT THIS TIME DUE TO UNCERTAINTY WITH THE MOVEMENT OF THE NARROW BAND. SNOW SHOWERS HAVE STARTED TO AFFECT THE SW CORNER OF THE CWFA ALREADY THIS MORNING. THE SNOW SHOWERS ARE RESULTING FROM COLDER AIR COMING ON THE NW FLOW IN PLACE. THIS NW FLOW IS ON THE SRN PERIPHERY OF A LARGER SCALE SFC TROUGH THAT CURRENTLY IS ORIENTED FROM THE STORM SYSTEM ACROSS THE NE U.S. ALL THE WAY TO MANITOBA. THE TROUGH IS RESULTING FROM BOTH THE UPPER WAVE DIVING SE TOWARD THE AREA... AND A CONTRIBUTION FROM THE GREAT LAKES. WE EXPECT THE SNOW SHOWERS TO INTENSIFY DURING THE DAY TODAY. THE SHORTWAVE DIVING IN FROM THE NW WILL HELP TO INCREASE INVERSION HTS TO OVER 10K FEET AND CAUSE THE SFC TROUGH TO SHARPEN UP. THIS WILL ENHANCE THE CONVERGENCE OVER PLENTY OF OVER LAKE INSTABILITY WITH DELTA T/S SITTING AROUND THE MID TO UPPER TEENS. ANOTHER FACTOR FOR HEAVIER SNOW AMOUNTS IS THE BEST CONVERGENCE OCCURS IN THE FAVORED LAYER OF THE DGZ AROUND 2-4K FT ALOFT. WE EXPECT TO SEE SNOW SHOWERS TO BECOME HEAVY ENOUGH TO SEE LOCAL SNOWFALL RATES OF OVER AN INCH PER HOUR UNDER THE NARROW BAND. WE EXPECT THE BAND TO GRADUALLY SHIFT NORTH THIS AFTERNOON RESULTING FROM THE UPPER FLOW AHEAD OF THE WAVE. THE FLOW WILL SHIFT FROM THE NW ORIENTATION TO A MORE WNW ORIENTATION. THIS WILL SHIFT THE HEAVIEST SNOW BAND FROM THE CURRENT LOCATION TO AT LEAST A HOLLAND TO HASTINGS CORRIDOR. SOME OF THE HIGHER RES MODELS ARE EVEN SHOWING THE BAND GETTING INTO A GRAND HAVEN TO SRN KENT COUNTY LINE...AND EVEN SOME ARE TAKING THIS TO A MUSKEGON TO GR LINE. THESE BANDS ARE QUITE TRICKY TO NAIL DOWN...BUT WHERE THEY GO CAN CAUSE QUITE AN IMPACT IN A SHORT TIME. OUR CONFIDENCE IS HIGH ENOUGH AT THIS TIME TO ADD IN OTTAWA AND BARRY COUNTIES FOR NOW. THERE IS SOME TIME TO WATCH THE EVOLUTION OF THE BAND AND EXPAND THE ADVISORY FURTHER NORTH INTO KENT AND MUSKEGON COUNTIES IF NEEDED AS IT WOULD NOT AFFECT THOSE AREAS UNTIL AT LEAST 21Z OR SO. THE BAND WILL END UP AT ITS FARTHEST NORTH ORIENTATION BETWEEN 00-03Z BEFORE IT THEN SINKS BACK SOUTH AND THEN EXITS THE AREA TOWARD 12Z TUE. THIS WILL OCCUR AS THE UPPER WAVE PASSES EAST OF THE AREA TOWARD 12Z TUE. WE CAN NOT RULE OUT AMOUNTS REACHING WARNING CRITERIA AT LOCATIONS THAT SEE THE BANDS LAST OVER A CERTAIN AREA THE LONGEST LIKE ALLEGAN COUNTY AND NEAR HOLLAND. WE WILL STICK WITH THE ADVISORY AND WATCH HOW SNOWFALL TRANSPIRES. MOST OF THE SNOW SHOWERS SHOULD TRANSITION OFFSHORE BY TUE MORNING AS THE FLOW BECOMES NNE BEHIND THE TROUGH PASSAGE. WE ACTUALLY EXPECT AT LEAST SOME CLEARING WHICH WOULD ALLOW TEMPS TO FALL OFF QUITE COLD AT INLAND LOCATIONS. WE COULD SEE SOME BELOW ZERO READINGS UP TOWARD LEOTA IF SKIES CLEAR ENOUGH. SOME SUN WILL BE FOUND ON TUE WITH THE SFC RIDGE MOVING OVERHEAD AND STRONG SUBSIDENCE BUILDING IN BETWEEN THE TWO UPPER WAVES. SOME LIGHT SNOW SHOWERS MAY MOVE INLAND ON TUE AS THE LOW LEVEL FLOW BECOMES WRLY WITH THE RIDGE. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 330 AM EST MON DEC 23 2013 MORE ACCUMULATING LAKE EFFECT/ENHANCED SNOW IS EXPECTED STARTING LATE CHRISTMAS EVE AND CONTINUING CHRISTMAS DAY AND THURSDAY. THIS IS FUELED BY A SERIES OF SHORTWAVES ASSOCIATED WITH A 120 KT UPPER LEVEL JET DIVING SE FROM WRN CANADA. TOTAL NEW SNOWFALL DURING THIS 48 HOUR PERIOD COULD EASILY EXCEED SIX INCHES WEST OF A CADILLAC TO KALAMAZOO LINE. THE FIRST BATCH OF SNOW FOR LATE CHRISTMAS EVE INTO CHRISTMAS MORNING IS A COMBINATION OF WARM ADVECTION SNOW WITH SSW FLOW LAKE ENHANCEMENT. SEVERAL INCHES OF ACCUMULATION ARE POSSIBLE ALONG THE LK MI COAST NORTH OF HOLLAND DURING THIS TIME. THEN A FAIRLY POTENT SHORTWAVE FOLLOWS IMMEDIATELY BEHIND THIS STARTING LATE CHRISTMAS DAY AND LASTING INTO THURSDAY. MEAN FLOW DURING THIS PERIOD IS WESTERLY BRINGING ADDITIONAL ACCUMULATIONS ALONG AND WEST OF HIGHWAY 131. MORE LAKE EFFECT SNOW SHOWERS ARE POSSIBLE THURSDAY NIGHT AND FRIDAY AS A FINAL NRN STREAM SHORTWAVE COMES THROUGH BEFORE THE UPPER FLOW GOES BRIEFLY ZONAL. SATURDAY CONTINUES TO LOOK LIKE A MILDER DAY AS H8 TEMPS ABOVE ZERO ARRIVE FROM THE WEST AS A LOW MOVES EAST ACROSS LK SUPERIOR. THE WARM UP SHOULD BE RATHER BRIEF HOWEVER AS MODELS SHOW MORE -20C H8 AIR SWEEPING IN ON SUNDAY OR SUNDAY NIGHT. THIS OUGHT TO GET THE LAKE EFFECT CRANKED UP AGAIN. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 703 AM EST MON DEC 23 2013 THE MAIN FOCUS WILL BE ON A NARROW BAND OF HEAVY LAKE EFFECT SNOW TODAY AND TONIGHT WHICH MAY OR MAY NOT IMPACT THE MKG AND GRR TERMINALS. CONFIDENCE IS LOW... BUT IT COULD BECOME ORIENTED FROM MKG TO GRR LATE THIS AFTERNOON AND EVENING AND BRING SEVERAL HOURS OF IFR/LIFR VSBYS IN MDT TO HVY SNOW. IT IS ALSO POSSIBLE THAT THE BAND WILL EXTEND WELL EAST INTO THE LAN AREA ALTHOUGH IT PROBABLY WOULD NOT BE AS INTENSE THERE. THE WEST-EAST ORIENTED BAND SHOULD MOVE SOUTHWARD AFTER 06Z TONIGHT AND BEGIN IMPACTING AZO/BTL/JXN WHILE SNOW ENDS AT MKG/GRR/LAN. OUTSIDE OF THE POTENTIAL INTENSE BAND OF SNOW TODAY AND TONIGHT... MVFR SHOULD BE THE PREDOMINATE FLIGHT CATEGORY WITH CIGS 1500-2500 FEET AND SCATTERED/OCNL LIGHT SNOW REDUCING VSBYS TO 3-5 MILES. && .MARINE... ISSUED AT 419 AM EST MON DEC 23 2013 WE HAVE ISSUED A SMALL CRAFT ADVISORY FOR THE SOUTHERN TWO MARINE ZONES. WEST TO NORTHWEST WINDS WILL COME UP ENOUGH TODAY TO REQUIRE A HEADLINE. THE NEXT HEADLINE WILL COME ON TUESDAY NIGHT AND INTO CHRISTMAS DAY. A SOLID SMALL CRAFT ADVISORY AND POSSIBLE GALE WILL OCCUR AHEAD OF THE CLIPPER SYSTEM EXPECTED TO MOVE IN AT THAT TIME. && .HYDROLOGY... ISSUED AT 857 AM EST MON DEC 23 2013 ARCTIC AIR RETURNS TODAY AND RIVERS ARE EXPECTED TO LOCK BACK IN PLACE WITH ICE OVER THE NEXT FEW DAYS. THIS SHOULD SERVE TO STABILIZE LEVELS. RELATIVELY FLAT ICE ON RIVERS IS A SIGN WATER IS FLOWING RELATIVELY SMOOTHLY BENEATH. TEMPERATURES WILL REMAIN BELOW FREEZING...AND WILL RESULT IN CONTINUED ICE GROWTH ON RIVERS IN SOUTHWEST LOWER MICHIGAN. UNDER THESE CONDITIONS THE THREAT FOR ICE JAMS IS LOW. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR MIZ056-064- 071-072. WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR MIZ050-057- 065. LM...SMALL CRAFT ADVISORY UNTIL 1 PM EST TUESDAY FOR LMZ844-845. && $$ UPDATE...TJT SYNOPSIS...NJJ SHORT TERM...NJJ LONG TERM...MEADE AVIATION...MEADE HYDROLOGY...WALTON MARINE...NJJ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1227 AM EST MON DEC 23 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 259 PM EST SUN DEC 22 2013 WATER VAPOR LOOP AND RUC ANALYSIS SHOWS SHORTWAVE AND ASSOC LOW PRESSURE SYSTEM LIFTING NE THROUGH THE LOWER GREAT LAKES. WEAKENING LIFT AS NOTED ON MID-LVL Q-VECT ANALYSIS AND EVENTUAL TRANSITION TO Q-VECT DIVERGENCE HAS QUICKLY DIMINISHED SYSTEM SNOW OVER THE EAST HALF OF UPPER MI THIS AFTERNOON. TOTAL SYSTEM SNOW ACCUMULATIONS ACROSS THE SCNTRL AND ERN COUNTIES IN THE WINTER WX ADVISORY AREA WILL LIKELY END UP IN THE 2 TO 3 INCH RANGE WITH A FEW SPOTS LOCALLY RECEIVING 4 INCHES. SNOW RATIOS APPEAR TO BE LOWER THAN EXPECTED IN PREV FCST LEADING TO DIMINISHED SNOW AMTS. SNOWFLAKES HERE AT NWS MQT ARE QUITE SMALL LEADING TO 6/1 SLR ON THE 18Z. DESPITE DIMINISHED SNOW AMTS...SMALL FLAKES ARE RESULTING IN REDUCED VSBYS. SOME ACCIDENTS ALSO REPORTED IN MENOMINEE COUNTY FROM SLIPPERY ROADS THIS AFTERNOON. WITH SYSTEM SNOW BASICALLY DONE THIS AFTERNOON...FOCUS WILL SHIFT TO LES WHICH IS EXPECTED TO IMPACT MAINLY WEST AND NCNTRL COUNTIES TONIGHT INTO MONDAY EVENING IN NE FLOW. GRADUALLY COLDER 8H TEMPS MOVING IN FM THE WEST BEHIND DEPARTED LOW SHOULD ALLOW SNOW RATIOS TO INCREASE THROUGH TONIGHT TO NEAR 20/1 WEST AND NCNTRL AS NOTED ON BUFKIT SNDG DATA. THE INCREASED INSTABILITY WITH COLDER OVER-WATER TEMPS ALONG WITH DEEPER MOISTURE AND ENHANCEMENT POTENTIAL FROM APPROACHING MID-LVL TROUGH FM THE NRN PLAINS SHOULD ALLOW FOR AN UPTICK IN LAKE EFFECT SNOW AMTS TONIGHT INTO MONDAY FOR FAR WEST AND NCNTRL COUNTIES. NO BIG CHANGES EXPECTED WITH FORECAST AS LES ADVISORIES STILL LOOK GOOD FOR GOGEBIC-ONTONAGON AND BARAGA-MARQUETTE COUNTIES HIGHLIGHTING STORM TOTAL SNOWFALL AMOUNTS POSSIBLY APPROACHING A FOOT OVER THE HIGHER TERRAIN AREAS FROM NORTH OF KIWD TO THE PORCUPINE MOUNTAINS AND FROM HERMAN THROUGH HURON MOUNTAINS TO NEGAUNEE. BIGGEST CONCERN OVER THE WRN COUNTIES IS THAT LES AMOUNTS MAY BE LESS THAN ORIGINALLY EXPECTED IN IWD AREA AS MODELS APPEAR TO BE HANGING ON TO THE NE FLOW A BIT LONGER THROUGH TONIGHT WHICH MAY PUSH THE BEST LOW-LVL CONVERGENCE AND THUS DOMINANT LES BANDS WEST OF KIWD. LES SHOULD EVENTUALLY PICK UP OVER THE FAR WEST BY MONDAY AFTERNOON AS WINDS BACK FM NE TO NNE BUT INITIAL LACK OF MODERATE SNOW COULD LIMIT STORM AMOUNTS IN THE KIWD AREA TO CLOSER TO 8 INCHES. PORCUPINE MOUNTAINS COULD STILL SEE TOTALS APPROACHING A FOOT THROUGH THE EVENT. AS MID-LVL TROUGH AXIS MOVES OVERHEAD LATE MON AFTERNOON...MODELS SHOW Q-VECT CONV DIMINISHING WHICH SHOULD LIMIT ENHANCEMENT POTENTIAL AT THAT TIME AND ALLOW FOR LES TO SLOWLY DIMINISH FROM WEST TO EAST INTO MON EVENING. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 259 PM EST SUN DEC 22 2013 THE UPPER TROUGH AXIS WILL BE OVER CENTRAL UPPER MI AT 00Z TUE...EXITING E BY 06Z TUE AS AN UPPER RIDGE MOVES TOWARD THE CWA FROM THE NW. THE RIDGE AXIS MOVES TO THE CENTRAL CWA BY 00Z WED. THE 12Z/22 NAM IS NOT AS STRONG OR AS FAST WITH THE RIDGE THAN THE GFS/ECMWF/GLOBAL GEM...AND ALSO HAS THE SFC TROUGH BEING STRONGER WITH A MESO LOW OVER SCENTRAL LAKE SUPERIOR EVEN AFTER THE RIDGE MOVES OVER. THINK THE SFC TROUGH WILL BE STRONGER THAN THE LARGER SCALE MODELS SHOW IT...BUT NOT AS STRONG AS THE NAM. EXPECT ONGOING LES AT THE START OF THE PERIOD TO TAPER OFF THROUGH MON NIGHT INTO TUE MORNING. GENERALLY...2-4 INCHES OF SNOW CAN BE EXPECTED MON NIGHT OVER THE HIGHER TERRAIN OF NCENTRAL UPPER MI...WITH OTHER AREAS NEAR LAKE SUPERIOR SEEING 1-2 INCHES. MODELS ARE IN GOOD AGREEMENT THAT A SHORTWAVE WILL BRING A QUICK /6 HOUR OR LESS DURATION/ COUPLE OF INCHES OF SNOW TO WEST AND CENTRAL UPPER MI TUE NIGHT. AS THE SHORTWAVE MOVES ACROSS THE ERN U.P. CHRISTMAS MORNING...SSE LOW LEVEL WINDS AND 850MB TEMPS AROUND -14C WILL ALLOW FOR LAKE ENHANCEMENT OFF LAKE MICHIGAN. COULD SEE ADVISORY LEVEL SNOW AMOUNTS IN EXCESS OF 6 INCHES IN AROUND 12 HOURS. COLDER AIR COMES IN WITH NW LOW LEVEL WINDS LATER CHRISTMAS DAY...LEADING TO NW WIND LES THAT WILL PERSIST UNTIL A RIDGE PASSES THU NIGHT INTO FRI. THE CWA MAY SEE ADDITIONAL LIGHT AREA WIDE SNOW FROM A SHORTWAVE THAT SOME MODELS SHOW MOVING THROUGH...BUT IF...WHEN AND WHERE ARE QUESTIONS THAT MAKE THIS VERY UNCERTAIN. ALTHOUGH CONFIDENCE DECREASES FARTHER OUT IN THE FORECAST PERIOD...MODELS DO GENERALLY AGREE ON MODERATING TEMPERATURES ON SAT AS A SHORTWAVE MOVES THROUGH THE REGION...WITH TEMPERATURES TURNING COLDER FOR NEXT SUN. RAN WITH A GENERAL CONSENSUS OF MODEL GUIDANCE FOR THIS PART OF THE FORECAST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1226 AM EST MON DEC 23 2013 EXPECT MAINLY MVFR CIGS AND MVFR/IFR VSBY TO PREVAIL OVERNIGHT AND MONDAY AT SAW AS LOW LEVEL MOISTURE REMAINS OVER THE AREA AND NNE WINDS PREVAIL ACROSS UPPER MICHIGAN BRINGING LAKE EFFECT SNOW INTO THE TAF SITES. LOWER VSBYS ARE ALSO EXPECTED TO MOVE INTO IWD AND CMX MONDAY MORNING AS WINDS BACK MORE NRLY. AS WINDS BECOME LIGHT BY LATE MON AFTERNOON...THE LES IS EXPECTED TO DIMINISH AS THE SNOWBANDS DO NOT MOVE AS FAR INLAND. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 259 PM EST SUN DEC 22 2013 NORTHEAST WINDS UP TO 30 KNOTS OVER WEST AND NORTH CENTRAL LAKE SUPERIOR WILL GRADUALLY DIMINISH THROUGH THE AFTERNOON/EARLY EVENING ...BUT GUSTS TO AROUND 25 KNOTS WILL CONTINUE INTO MONDAY. THESE WINDS ALONG WITH FALLING TEMPS THIS AFTERNOON/EVENING WILL PRODUCE HEAVY FREEZING SPRAY TODAY THROUGH MONDAY WHEN THE WINDS FINALLY SLACKEN. WINDS BEGIN TO INCREASE ONCE AGAIN TUESDAY NIGHT INTO WEDNESDAY AS THE NEXT SYSTEM PASSES TO THE NORTH OF LAKE SUPERIOR. GALE FORCE GUSTS OVER 35 KNOTS ARE POSSIBLE OVER EASTERN LAKE SUPERIOR TUESDAY NIGHT AND EARLY WEDNESDAY MORNING. WINDS GRADUALLY DIMINISH ONCE AGAIN WEDNESDAY NIGHT INTO FRIDAY AS HIGH PRESSURE STARTS TO BUILD INTO THE REGION. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL MIDNIGHT EST /11 PM CST/ TONIGHT FOR MIZ002-009. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST TUESDAY FOR MIZ004-005. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR LSZ162-263-264. LAKE MICHIGAN... NONE. && $$ SHORT TERM...VOSS LONG TERM...TITUS AVIATION...JLB MARINE...VOSS
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1246 PM CST MON DEC 23 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CST MON DEC 23 2013 LIGHT SNOW CONTINUES EARLY THIS MORNING FROM CENTRAL MN THROUGH THE TWIN CITIES AND WEST CENTRAL WI UNDER AN UPPER LEVEL TROUGH. ANIMATION OF THE KMPX RADAR INDICATES A LOW/MID LEVEL CIRCULATION ACROSS CENTRAL MN... WHICH VERIFIES WELL WITH THE RAP AVERAGE 850-700MB HEIGHT FIELD. THE UPPER TROUGH AND LOW LEVEL CYCLONIC CIRCULATION WILL DRIFT EVER SO SLOWLY TO THE SOUTHEAST THROUGH THIS EVENING. THIS WILL MAINTAIN PLENTY OF CLOUDS AND LIGHT SNOW ACROSS EASTERN MN AND WESTERN WI THROUGH THE DAY WITH THE LIGHT SNOW DIMINISHING ACROSS WEST CENTRAL WI THIS EVENING. SNOW AMOUNTS TODAY ARE IN THE TRACE TO 1 INCH CATEGORY FOR THE MN CWA WITH 1 TO 2 INCHES FOR WEST CENTRAL WI. SNOW AMOUNTS IN WEST CENTRAL WI TONIGHT ARE LESS THAN A HALF INCH. THE TEMPERATURE FORECAST FOR TODAY AND TONIGHT IS RATHER PROBLEMATIC. ONE CONCERN TODAY IS HOW MUCH OF A REBOUND WE WILL HAVE ACROSS THE WESTERN HALF OF MINNESOTA AS THE ARCTIC AIR CONTINUES TO POUR IN WHILE EASTERN AREAS HAVE SOME INSULATION FROM THE CLOUDS. JUST ABOUT EVERYBODY IN THE MN RIVER VALLEY EARLY THIS MORNING IS CURRENTLY NEAR 10 BELOW. LOWS COULD EASILY REACH 15 BELOW TO 20 BELOW ZERO BY DAYBREAK. THE CURRENT THINKING IS THAT WE WILL ONLY MAKE IF BACK TO THE 5 BELOW TO 10 BELOW RANGE IN THE WEST TODAY WITH SINGLE DIGITS IN EASTERN MN WITH SOME TEENS IN OUR FAR EASTERN COUNTIES IN WI. WITH THE ARCTIC HIGH REACHING OUR WESTERN MN COUNTIES THIS EVENING...TEMPERATURES SHOULD CRATER FOR A 6 TO 8 HOUR PERIOD BEFORE RISING AFTER MIDNIGHT AS SOUTHERLY LOW LEVEL FLOW DEVELOPS AHEAD OF AN APPROACHING CLIPPER. HENCE... LOWS TONIGHT ARE A BIG CONCERN. THE GEM AND ECMWF ARE ON THE COLD SIDE OF GUIDANCE WITH 20 BELOW TO 30 BELOW ZERO FOR MOST OF OUR MN CWA WITH 10 BELOW TO 20 BELOW ZERO IN WI. THE AREA WHERE THE COLDEST TEMPERATURES WILL LIKELY BE REACHED IS ACROSS CENTRAL MN WHERE SEVERAL INCHES OF NEW SNOW HAS FALLEN AND THE SNOW DEPTH IS NEARLY A FOOT. THEREFORE...WENT NEAR 25 BELOW ACROSS CENTRAL MN WITH 15 BELOW TO 20 BELOW ACROSS SOUTHERN MN WITH AROUND 10 BELOW IN THE TWIN CITIES AS WEST CENTRAL WI. A NON-DIURNAL TEMPERATURE TREND WAS INSERTED ACROSS WEST CENTRAL MN DURING THE OVERNIGHT HOURS. THE COLD TEMPERATURES AND NORTHWEST WINDS OF 10 TO 20 MPH THROUGH THIS EVENING CERTAINLY SUPPORT THE CURRENT WIND CHILL WARNING AND WIND CHILL ADVISORY HEADLINES WITH NO CHANGES BEING MADE AT THIS TIME. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 356 AM CST MON DEC 23 2013 NOT MUCH HAS CHANGED IN THE LONG TERM WITH THIS UPDATE. WE WILL MAINTAIN NORTHWEST FLOW AS WE REMAIN WEDGED BETWEEN A MEAN ERN PAC RIDGE AND ERN NOAM TROUGH. TUESDAY STILL LOOKS TO FEATURE STRONG SOUTHERLY WINDS AND A QUICK BURST OF SNOW AS THE STRONG WAVE CURRENTLY ROUNDING THE TOP OF THE RIDGE OVER THE GULF OF ALASKA COMES SLIDING ACROSS THE AREA. MODEL AGREEMENT REMAINS HIGH WITH THIS SNOW...WITH ONLY MINOR TIMING DIFFERENCES EXISTING AT THIS POINT. ALL MODELS SHOW FAIRLY WIDESPREAD 0.1 TO 0.2 INCH QPF AMOUNTS FALLING WITH THIS SYSTEM. ONLY EXPECT SNOW RATIOS TO RANGE FROM 15-18:1 DURING THE HEAVIEST SNOW AS COMBINATION OF STRONG WAA IN THE H85-H7 LAYER WILL LIMIT THE DEPTH OF THE DENDRITIC GROWTH ZONE AND STRONG WINDS FROM THE SFC THROUGH THE DEPTH OF THE CLOUD LAYER WILL HELP BREAK APART ANY CRYSTALS THAT TRY TO GET TOO BIG. THESE RATIOS WITH THE EXPECTED QPF WILL RESULT IN A GOOD 1.5 TO 3.5 INCHES OF SNOW AREA WIDE. NAM/GFS CONTINUE TO SHOW MIXING RATIOS ON THE 295K SFC UP AROUND 2.5 G/KG...WHICH SUPPORTS THE CURRENTLY EXPECTED SNOWFALL AMOUNTS. ALTHOUGH THESE AMOUNTS FALL BELOW THE 4 INCH BENCHMARK FOR A WINTER WEATHER ADVY...THE FACT THAT THIS WILL BE A FAIRLY HEALTHY BURST OF SNOW FOR ABOUT 4 HOURS DURING THE AFTERNOON/EVENING OF CHRISTMAS EVE WHEN TRAVEL WILL BE HEAVIER ACROSS THE AREA...FUTURE SHIFTS WILL HAVE TO WEIGH THE MERITS OF ISSUING AN ADVY BASED ON THE POTENTIAL TRAVEL IMPACTS. FOR CHRISTMAS DAY...ANOTHER STRONG UPPER WAVE WILL BE PASSING DOWN THROUGH THE AREA. THE NAM IS SHOWING HEIGHT FALLS WITH THIS WAVE ON THE ORDER OF 160M IN 12 HOURS...WITH A 5 UNIT PV ANOMALY COMING DOWN AS WELL. ALL OF THIS POINTS TO ANOTHER BURST OF SNOW AS THIS COMES DOWN...THOUGH IT WILL BE COMING DOWN IN THE DRY WAKE OF TUESDAYS SYSTEM...AS THOSE SPEC HUMIDITIES THAT WILL BE UP AROUND 2.5 G/KG TUESDAY WILL BE DOWN BETWEEN 0.5 AND 1 G/KG WEDNESDAY...HENCE WHY QPF INDICATED BY THE MODELS IS SPOTTY AT BEST. THIS JUST LOOKS TO BE ANOTHER SHOT AT SEEING A FAIRLY WIDESPREAD HALF INCH OF SNOW ON LIQUID AMOUNTS THAT ARE A TRACE OR A HUNDREDTH OF AN INCH. AFTER THIS WE MAY SEE REPEAT PERFORMANCES WITH SOME LIGHT SNOW/FLURRIES AGAIN ON THURSDAY AND FRIDAY AS WE CONTINUE TO GET PEPPERED BY WEAK UPPER WAVES IN THE NW FLOW. FOR SATURDAY...THE WRN RIDGE LOOKS TO SHIFT FAR ENOUGH EAST TO PUSH THESE WAVES NORTH OF THE AREA...BUT THE RETURN OF THE ARCTIC AIR SUNDAY WILL BRING ABOUT THE NEXT SHOT AT A DUSTING. TEMPERATURES WILL BE ON A BIT OF A ROLLER COASTER OVER THE NEXT WEEK...THOUGH WE WILL BE BOUNCING BETWEEN NEAR NORMAL AND ABOUT 20 DEGREES BELOW NORMAL. WE WILL MAINTAIN OUR RESIDENCE IN THE ARCTIC AIR THROUGH TONIGHT...BRIEFLY SHIFT OUT OF IT TUESDAY THROUGH WEDNESDAY...RECEIVE A MORE GLANCING BLOW OF ARCTIC AIR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...GET OUR WARMEST BREAK FROM THE ARCTIC AIR FRIDAY AND SATURDAY...THEN SEE WHAT COULD BE OUR COLDEST BLAST OF AIR YET FOR SATURDAY NIGHT INTO SUNDAY OF NEXT WEEKEND. FROM THE WIND CHILL HEADLINE END OF THINGS...THE GLANCING BLOW OF ARCTIC AIR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT LOOKS TO BE JUST WARM ENOUGH TO CEASE THE NEED FOR ANY WIND CHILL HEADLINES AFTER TUESDAY MORNING UNTIL THE NEXT HEALTHY DOSE OF ARCTIC AIR RETURNS SUNDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1232 PM CST MON DEC 23 2013 MVFR VIS/CIGS WITH LIGHT SNOW WILL LINGER FOR THE REMAINDER OF THE AFTERNOON IN WI...BUT SLOWLY CLEAR FROM WEST TO EAST WITH TIME. VFR TONIGHT WITH CLEAR SKIES AND FRIGID TEMPS. ACCUMULATING SNOW IS EXPECTED TOMORROW. EXPECT CONDITIONS TO DETERIORATE QUICKLY ONCE THE SNOW BEGINS TOMORROW AFTERNOON. KMSP... NO AVIATIN WEATHER CONCERNS IN THE COLD SHORT TERM WITH NEARLY CLOUD FREE SKIES. WE HAVE HIGH CONFIDENCE THAT THE SNOW WILL BEGIN SOMETIME BETWEEN 12-1PM TOMORROW AND CIGS/VIS WILL QUICKLY BE REDUCED. THE EVENING RUSH TONIGHT AND TUESDAY MORNING COMMUTE WILL BE FINE WITH VFR CONDITIONS. THIS WILL DEFITELY IMPACT THE EVENING RUSH...HOWEVER...WITH IFR/LIFR CONDITIONS DURING THE MID TO LATE AFTERNOON. WE WILL CONTINUE TO REFINE THE TIMING OF THE ONSET OF SNOW TOMORROW...BUT WE FEEL WE HAVE A GOOD HANDLE /WITHIN A COUPLE HOURS/ AS OF RIGHT NOW. /OUTLOOK FOR KMSP/ TUE NIGHT...IFR WITH SN IN THE EVENING WINDS S AT 10G20KTS. WED...MVFR WITH -SN/BLSN POSSIBLE. WINDS W AT 15G25KTS. THU...VFR. WINDS W AT 10KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR MNZ042-043- 049>051-058-059-066>069-076-077-084-085-091>093. WIND CHILL WARNING UNTIL NOON CST TUESDAY FOR MNZ041-047-048- 054>057-064-065-073>075-082-083. WI...NONE. && $$ SHORT TERM...RAH LONG TERM...MPG AVIATION...CLF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
547 AM CST MON DEC 23 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CST MON DEC 23 2013 LIGHT SNOW CONTINUES EARLY THIS MORNING FROM CENTRAL MN THROUGH THE TWIN CITIES AND WEST CENTRAL WI UNDER AN UPPER LEVEL TROUGH. ANIMATION OF THE KMPX RADAR INDICATES A LOW/MID LEVEL CIRCULATION ACROSS CENTRAL MN... WHICH VERIFIES WELL WITH THE RAP AVERAGE 850-700MB HEIGHT FIELD. THE UPPER TROUGH AND LOW LEVEL CYCLONIC CIRCULATION WILL DRIFT EVER SO SLOWLY TO THE SOUTHEAST THROUGH THIS EVENING. THIS WILL MAINTAIN PLENTY OF CLOUDS AND LIGHT SNOW ACROSS EASTERN MN AND WESTERN WI THROUGH THE DAY WITH THE LIGHT SNOW DIMINISHING ACROSS WEST CENTRAL WI THIS EVENING. SNOW AMOUNTS TODAY ARE IN THE TRACE TO 1 INCH CATEGORY FOR THE MN CWA WITH 1 TO 2 INCHES FOR WEST CENTRAL WI. SNOW AMOUNTS IN WEST CENTRAL WI TONIGHT ARE LESS THAN A HALF INCH. THE TEMPERATURE FORECAST FOR TODAY AND TONIGHT IS RATHER PROBLEMATIC. ONE CONCERN TODAY IS HOW MUCH OF A REBOUND WE WILL HAVE ACROSS THE WESTERN HALF OF MINNESOTA AS THE ARCTIC AIR CONTINUES TO POUR IN WHILE EASTERN AREAS HAVE SOME INSULATION FROM THE CLOUDS. JUST ABOUT EVERYBODY IN THE MN RIVER VALLEY EARLY THIS MORNING IS CURRENTLY NEAR 10 BELOW. LOWS COULD EASILY REACH 15 BELOW TO 20 BELOW ZERO BY DAYBREAK. THE CURRENT THINKING IS THAT WE WILL ONLY MAKE IF BACK TO THE 5 BELOW TO 10 BELOW RANGE IN THE WEST TODAY WITH SINGLE DIGITS IN EASTERN MN WITH SOME TEENS IN OUR FAR EASTERN COUNTIES IN WI. WITH THE ARCTIC HIGH REACHING OUR WESTERN MN COUNTIES THIS EVENING...TEMPERATURES SHOULD CRATER FOR A 6 TO 8 HOUR PERIOD BEFORE RISING AFTER MIDNIGHT AS SOUTHERLY LOW LEVEL FLOW DEVELOPS AHEAD OF AN APPROACHING CLIPPER. HENCE... LOWS TONIGHT ARE A BIG CONCERN. THE GEM AND ECMWF ARE ON THE COLD SIDE OF GUIDANCE WITH 20 BELOW TO 30 BELOW ZERO FOR MOST OF OUR MN CWA WITH 10 BELOW TO 20 BELOW ZERO IN WI. THE AREA WHERE THE COLDEST TEMPERATURES WILL LIKELY BE REACHED IS ACROSS CENTRAL MN WHERE SEVERAL INCHES OF NEW SNOW HAS FALLEN AND THE SNOW DEPTH IS NEARLY A FOOT. THEREFORE...WENT NEAR 25 BELOW ACROSS CENTRAL MN WITH 15 BELOW TO 20 BELOW ACROSS SOUTHERN MN WITH AROUND 10 BELOW IN THE TWIN CITIES AS WEST CENTRAL WI. A NON-DIURNAL TEMPERATURE TREND WAS INSERTED ACROSS WEST CENTRAL MN DURING THE OVERNIGHT HOURS. THE COLD TEMPERATURES AND NORTHWEST WINDS OF 10 TO 20 MPH THROUGH THIS EVENING CERTAINLY SUPPORT THE CURRENT WIND CHILL WARNING AND WIND CHILL ADVISORY HEADLINES WITH NO CHANGES BEING MADE AT THIS TIME. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 356 AM CST MON DEC 23 2013 NOT MUCH HAS CHANGED IN THE LONG TERM WITH THIS UPDATE. WE WILL MAINTAIN NORTHWEST FLOW AS WE REMAIN WEDGED BETWEEN A MEAN ERN PAC RIDGE AND ERN NOAM TROUGH. TUESDAY STILL LOOKS TO FEATURE STRONG SOUTHERLY WINDS AND A QUICK BURST OF SNOW AS THE STRONG WAVE CURRENTLY ROUNDING THE TOP OF THE RIDGE OVER THE GULF OF ALASKA COMES SLIDING ACROSS THE AREA. MODEL AGREEMENT REMAINS HIGH WITH THIS SNOW...WITH ONLY MINOR TIMING DIFFERENCES EXISTING AT THIS POINT. ALL MODELS SHOW FAIRLY WIDESPREAD 0.1 TO 0.2 INCH QPF AMOUNTS FALLING WITH THIS SYSTEM. ONLY EXPECT SNOW RATIOS TO RANGE FROM 15-18:1 DURING THE HEAVIEST SNOW AS COMBINATION OF STRONG WAA IN THE H85-H7 LAYER WILL LIMIT THE DEPTH OF THE DENDRITIC GROWTH ZONE AND STRONG WINDS FROM THE SFC THROUGH THE DEPTH OF THE CLOUD LAYER WILL HELP BREAK APART ANY CRYSTALS THAT TRY TO GET TOO BIG. THESE RATIOS WITH THE EXPECTED QPF WILL RESULT IN A GOOD 1.5 TO 3.5 INCHES OF SNOW AREA WIDE. NAM/GFS CONTINUE TO SHOW MIXING RATIOS ON THE 295K SFC UP AROUND 2.5 G/KG...WHICH SUPPORTS THE CURRENTLY EXPECTED SNOWFALL AMOUNTS. ALTHOUGH THESE AMOUNTS FALL BELOW THE 4 INCH BENCHMARK FOR A WINTER WEATHER ADVY...THE FACT THAT THIS WILL BE A FAIRLY HEALTHY BURST OF SNOW FOR ABOUT 4 HOURS DURING THE AFTERNOON/EVENING OF CHRISTMAS EVE WHEN TRAVEL WILL BE HEAVIER ACROSS THE AREA...FUTURE SHIFTS WILL HAVE TO WEIGH THE MERITS OF ISSUING AN ADVY BASED ON THE POTENTIAL TRAVEL IMPACTS. FOR CHRISTMAS DAY...ANOTHER STRONG UPPER WAVE WILL BE PASSING DOWN THROUGH THE AREA. THE NAM IS SHOWING HEIGHT FALLS WITH THIS WAVE ON THE ORDER OF 160M IN 12 HOURS...WITH A 5 UNIT PV ANOMALY COMING DOWN AS WELL. ALL OF THIS POINTS TO ANOTHER BURST OF SNOW AS THIS COMES DOWN...THOUGH IT WILL BE COMING DOWN IN THE DRY WAKE OF TUESDAYS SYSTEM...AS THOSE SPEC HUMIDITIES THAT WILL BE UP AROUND 2.5 G/KG TUESDAY WILL BE DOWN BETWEEN 0.5 AND 1 G/KG WEDNESDAY...HENCE WHY QPF INDICATED BY THE MODELS IS SPOTTY AT BEST. THIS JUST LOOKS TO BE ANOTHER SHOT AT SEEING A FAIRLY WIDESPREAD HALF INCH OF SNOW ON LIQUID AMOUNTS THAT ARE A TRACE OR A HUNDREDTH OF AN INCH. AFTER THIS WE MAY SEE REPEAT PERFORMANCES WITH SOME LIGHT SNOW/FLURRIES AGAIN ON THURSDAY AND FRIDAY AS WE CONTINUE TO GET PEPPERED BY WEAK UPPER WAVES IN THE NW FLOW. FOR SATURDAY...THE WRN RIDGE LOOKS TO SHIFT FAR ENOUGH EAST TO PUSH THESE WAVES NORTH OF THE AREA...BUT THE RETURN OF THE ARCTIC AIR SUNDAY WILL BRING ABOUT THE NEXT SHOT AT A DUSTING. TEMPERATURES WILL BE ON A BIT OF A ROLLER COASTER OVER THE NEXT WEEK...THOUGH WE WILL BE BOUNCING BETWEEN NEAR NORMAL AND ABOUT 20 DEGREES BELOW NORMAL. WE WILL MAINTAIN OUR RESIDENCE IN THE ARCTIC AIR THROUGH TONIGHT...BRIEFLY SHIFT OUT OF IT TUESDAY THROUGH WEDNESDAY...RECEIVE A MORE GLANCING BLOW OF ARCTIC AIR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...GET OUR WARMEST BREAK FROM THE ARCTIC AIR FRIDAY AND SATURDAY...THEN SEE WHAT COULD BE OUR COLDEST BLAST OF AIR YET FOR SATURDAY NIGHT INTO SUNDAY OF NEXT WEEKEND. FROM THE WIND CHILL HEADLINE END OF THINGS...THE GLANCING BLOW OF ARCTIC AIR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT LOOKS TO BE JUST WARM ENOUGH TO CEASE THE NEED FOR ANY WIND CHILL HEADLINES AFTER TUESDAY MORNING UNTIL THE NEXT HEALTHY DOSE OF ARCTIC AIR RETURNS SUNDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 545 AM CST MON DEC 23 2013 A HODGEPODGE OF CEILING AND VISIBILITY CONDITIONS THIS MORNING ACROSS EASTERN MN AND WESTERN WI AS AN UPPER LEVEL LOW OVERHEAD DRIFTS SLOWLY SE. THE ARCTIC AIR SPILLING IN FROM THE WEST NORTHWEST HAS AIDED IN HELPING CEILINGS RISE INTO THE VFR CATEGORY FROM KSTC THROUGH KMSP EVEN THROUGH MVFR VSBYS IN -SN CONTINUE. THESE TWO SITES SHOULD SEE IMPROVEMENT TO VFR VSBYS BY LATE IN THE MORNING. KRNH AND KEAU WILL BE SLOWER TO IMPROVE SINCE THEY WILL BE JUST ON THE EAST SIDE OF THE TROUGH AXIS ALOFT. IMPROVEMENT FORECAST TO VFR BY LATE AFTERNOON/EVENING RESPECTIVELY. NOT TOO MANY PROBLEMS FOR KAXN AND KRWF BUT THERE WILL BE BRISK NW WINDS THIS MORNING WHICH MAY CAUSE SOME VSBY RESTRICTION IN BLSN AT KRWF. ARCTIC HIGH MOVING IN TONIGHT WITH VFR CONDITIONS AND VERY COLD TEMPERATURES. KMSP... MVFR VSBY IN -SN IMPROVING TO VFR 15Z-18Z. CEILING SHOULD STAY AT OR ABOVE 035 THIS MORNING ALTHOUGH A BRIEF PERIOD OF MVFR CAN/T BE RULED OUT. SCT CONDITIONS DEVELOPING THIS AFTERNOON. NORTHWEST WINDS 12 KNOTS TODAY...BACKING TO WEST 5 KNOTS THIS EVENING AND SE 8 KNOTS TUESDAY MORNING. SNOW SPREADING IN TUESDAY AFTERNOON BETWEEN 18Z-21Z AND CONTINUING THROUGH THE EVENING. SNOW ACCUMULATION AROUND 3 INCHES LIKELY. /OUTLOOK FOR KMSP/ TUE...VFR MRNG. MVFR/IFR WITH SN IN THE AFTN. WINDS S AT 10G20KTS. WED...MVFR WITH -SN/BLSN POSSIBLE. WINDS W AT 15G25KTS. THU...VFR. WINDS W AT 10KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR MNZ042-043- 049>051-058-059-066>069-076-077-084-085-091>093. WIND CHILL WARNING UNTIL NOON CST TUESDAY FOR MNZ041-047-048- 054>057-064-065-073>075-082-083. WI...NONE. && $$ SHORT TERM...RAH LONG TERM...MPG AVIATION...RAH
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
400 AM CST MON DEC 23 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CST MON DEC 23 2013 LIGHT SNOW CONTINUES EARLY THIS MORNING FROM CENTRAL MN THROUGH THE TWIN CITIES AND WEST CENTRAL WI UNDER AN UPPER LEVEL TROUGH. ANIMATION OF THE KMPX RADAR INDICATES A LOW/MID LEVEL CIRCULATION ACROSS CENTRAL MN... WHICH VERIFIES WELL WITH THE RAP AVERAGE 850-700MB HEIGHT FIELD. THE UPPER TROUGH AND LOW LEVEL CYCLONIC CIRCULATION WILL DRIFT EVER SO SLOWLY TO THE SOUTHEAST THROUGH THIS EVENING. THIS WILL MAINTAIN PLENTY OF CLOUDS AND LIGHT SNOW ACROSS EASTERN MN AND WESTERN WI THROUGH THE DAY WITH THE LIGHT SNOW DIMINISHING ACROSS WEST CENTRAL WI THIS EVENING. SNOW AMOUNTS TODAY ARE IN THE TRACE TO 1 INCH CATEGORY FOR THE MN CWA WITH 1 TO 2 INCHES FOR WEST CENTRAL WI. SNOW AMOUNTS IN WEST CENTRAL WI TONIGHT ARE LESS THAN A HALF INCH. THE TEMPERATURE FORECAST FOR TODAY AND TONIGHT IS RATHER PROBLEMATIC. ONE CONCERN TODAY IS HOW MUCH OF A REBOUND WE WILL HAVE ACROSS THE WESTERN HALF OF MINNESOTA AS THE ARCTIC AIR CONTINUES TO POUR IN WHILE EASTERN AREAS HAVE SOME INSOLATION FROM THE CLOUDS. JUST ABOUT EVERYBODY IN THE MN RIVER VALLEY EARLY THIS MORNING IS CURRENTLY NEAR 10 BELOW. LOWS COULD EASILY REACH 15 BELOW TO 20 BELOW ZERO BY DAYBREAK. THE CURRENT THINKING IS THAT WE WILL ONLY MAKE IF BACK TO THE 5 BELOW TO 10 BELOW RANGE IN THE WEST TODAY WITH SINGLE DIGITS IN EASTERN MN WITH SOME TEENS IN OUR FAR EASTERN COUNTIES IN WI. WITH THE ARCTIC HIGH REACHING OUR WESTERN MN COUNTIES THIS EVENING...TEMPERATURES SHOULD CRATER FOR A 6 TO 8 HOUR PERIOD BEFORE RISING AFTER MIDNIGHT AS SOUTHERLY LOW LEVEL FLOW DEVELOPS AHEAD OF AN APPROACHING CLIPPER. HENCE... LOWS TONIGHT ARE A BIG CONCERN. THE GEM AND ECMWF ARE ON THE COLD SIDE OF GUIDANCE WITH 20 BELOW TO 30 BELOW ZERO FOR MOST OF OUR MN CWA WITH 10 BELOW TO 20 BELOW ZERO IN WI. THE AREA WHERE THE COLDEST TEMPERATURES WILL LIKELY BE REACHED IS ACROSS CENTRAL MN WHERE SEVERAL INCHES OF NEW SNOW HAS FALLEN AND THE SNOW DEPTH IS NEARLY A FOOT. THEREFORE...WENT NEAR 25 BELOW ACROSS CENTRAL MN WITH 15 BELOW TO 20 BELOW ACROSS SOUTHERN MN WITH AROUND 10 BELOW IN THE TWIN CITIES AS WEST CENTRAL WI. A NON-DIURNAL TEMPERATURE TREND WAS INSERTED ACROSS WEST CENTRAL MN DURING THE OVERNIGHT HOURS. THE COLD TEMPERATURES AND NORTHWEST WINDS OF 10 TO 20 MPH THROUGH THIS EVENING CERTAINLY SUPPORT THE CURRENT WIND CHILL WARNING AND WIND CHILL ADVISORY HEADLINES WITH NO CHANGES BEING MADE AT THIS TIME. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 356 AM CST MON DEC 23 2013 NOT MUCH HAS CHANGED IN THE LONG TERM WITH THIS UPDATE. WE WILL MAINTAIN NORTHWEST FLOW AS WE REMAIN WEDGED BETWEEN A MEAN ERN PAC RIDGE AND ERN NOAM TROUGH. TUESDAY STILL LOOKS TO FEATURE STRONG SOUTHERLY WINDS AND A QUICK BURST OF SNOW AS THE STRONG WAVE CURRENTLY ROUNDING THE TOP OF THE RIDGE OVER THE GULF OF ALASKA COMES SLIDING ACROSS THE AREA. MODEL AGREEMENT REMAINS HIGH WITH THIS SNOW...WITH ONLY MINOR TIMING DIFFERENCES EXISTING AT THIS POINT. ALL MODELS SHOW FAIRLY WIDESPREAD 0.1 TO 0.2 INCH QPF AMOUNTS FALLING WITH THIS SYSTEM. ONLY EXPECT SNOW RATIOS TO RANGE FROM 15-18:1 DURING THE HEAVIEST SNOW AS COMBINATION OF STRONG WAA IN THE H85-H7 LAYER WILL LIMIT THE DEPTH OF THE DENDRITIC GROWTH ZONE AND STRONG WINDS FROM THE SFC THROUGH THE DEPTH OF THE CLOUD LAYER WILL HELP BREAK APART ANY CRYSTALS THAT TRY TO GET TOO BIG. THESE RATIOS WITH THE EXPECTED QPF WILL RESULT IN A GOOD 1.5 TO 3.5 INCHES OF SNOW AREA WIDE. NAM/GFS CONTINUE TO SHOW MIXING RATIOS ON THE 295K SFC UP AROUND 2.5 G/KG...WHICH SUPPORTS THE CURRENTLY EXPECTED SNOWFALL AMOUNTS. ALTHOUGH THESE AMOUNTS FALL BELOW THE 4 INCH BENCHMARK FOR A WINTER WEATHER ADVY...THE FACT THAT THIS WILL BE A FAIRLY HEALTHY BURST OF SNOW FOR ABOUT 4 HOURS DURING THE AFTERNOON/EVENING OF CHRISTMAS EVE WHEN TRAVEL WILL BE HEAVIER ACROSS THE AREA...FUTURE SHIFTS WILL HAVE TO WEIGH THE MERITS OF ISSUING AN ADVY BASED ON THE POTENTIAL TRAVEL IMPACTS. FOR CHRISTMAS DAY...ANOTHER STRONG UPPER WAVE WILL BE PASSING DOWN THROUGH THE AREA. THE NAM IS SHOWING HEIGHT FALLS WITH THIS WAVE ON THE ORDER OF 160M IN 12 HOURS...WITH A 5 UNIT PV ANOMALY COMING DOWN AS WELL. ALL OF THIS POINTS TO ANOTHER BURST OF SNOW AS THIS COMES DOWN...THOUGH IT WILL BE COMING DOWN IN THE DRY WAKE OF TUESDAYS SYSTEM...AS THOSE SPEC HUMIDITIES THAT WILL BE UP AROUND 2.5 G/KG TUESDAY WILL BE DOWN BETWEEN 0.5 AND 1 G/KG WEDNESDAY...HENCE WHY QPF INDICATED BY THE MODELS IS SPOTTY AT BEST. THIS JUST LOOKS TO BE ANOTHER SHOT AT SEEING A FAIRLY WIDESPREAD HALF INCH OF SNOW ON LIQUID AMOUNTS THAT ARE A TRACE OR A HUNDREDTH OF AN INCH. AFTER THIS WE MAY SEE REPEAT PERFORMANCES WITH SOME LIGHT SNOW/FLURRIES AGAIN ON THURSDAY AND FRIDAY AS WE CONTINUE TO GET PEPPERED BY WEAK UPPER WAVES IN THE NW FLOW. FOR SATURDAY...THE WRN RIDGE LOOKS TO SHIFT FAR ENOUGH EAST TO PUSH THESE WAVES NORTH OF THE AREA...BUT THE RETURN OF THE ARCTIC AIR SUNDAY WILL BRING ABOUT THE NEXT SHOT AT A DUSTING. TEMPERATURES WILL BE ON A BIT OF A ROLLER COASTER OVER THE NEXT WEEK...THOUGH WE WILL BE BOUNCING BETWEEN NEAR NORMAL AND ABOUT 20 DEGREES BELOW NORMAL. WE WILL MAINTAIN OUR RESIDENCE IN THE ARCTIC AIR THROUGH TONIGHT...BRIEFLY SHIFT OUT OF IT TUESDAY THROUGH WEDNESDAY...RECEIVE A MORE GLANCING BLOW OF ARCTIC AIR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...GET OUR WARMEST BREAK FROM THE ARCTIC AIR FRIDAY AND SATURDAY...THEN SEE WHAT COULD BE OUR COLDEST BLAST OF AIR YET FOR SATURDAY NIGHT INTO SUNDAY OF NEXT WEEKEND. FROM THE WIND CHILL HEADLINE END OF THINGS...THE GLANCING BLOW OF ARCTIC AIR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT LOOKS TO BE JUST WARM ENOUGH TO CEASE THE NEED FOR ANY WIND CHILL HEADLINES AFTER TUESDAY MORNING UNTIL THE NEXT HEALTHY DOSE OF ARCTIC AIR RETURNS SUNDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1137 PM CST SUN DEC 22 2013 MVFR CONDITIONS EXPECTED TO PERSIST FOR MUCH OF THE OVERNIGHT AND INTO MONDAY ACROSS CENTRAL/EASTERN MN AND WESTERN WI. MAINLY VFR AT AXN AND RWF AS THESE SITES REMAIN ON THE WESTERN PERIPHERY OF THE SYSTEM GENERATING SNOW TO THE EAST. DRIER AIR WILL FINALLY PUSH INTO THE REST OF THE TAF SITES LATE MONDAY. NORTHWEST WINDS AROUND 10 KTS WILL PERSIST THROUGH MONDAY...BECOMING LIGHT AND VARIABLE MONDAY EVENING. KMSP...MVFR CONDITIONS THROUGH MOST OF MONDAY IN LIGHT SNOW...WITH VFR CONDITIONS BY MID AFTERNOON. SNOW ACCUMULATIONS WILL REMAIN AROUND AN INCH OR LESS. /OUTLOOK FOR KMSP/ TUE...VFR WITH MVFR/IFR AND -SN BY AFTN. WINDS S AT 10G20KTS. WED...MVFR WITH -SN/BLSN POSSIBLE. WINDS W AT 15G25KTS. THU...VFR. WINDS W AT 10KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR MNZ042-043- 049>051-058-059-066>069-076-077-084-085-091>093. WIND CHILL WARNING UNTIL NOON CST TUESDAY FOR MNZ041-047-048- 054>057-064-065-073>075-082-083. WI...NONE. && $$ SHORT TERM...RAH LONG TERM...MPG AVIATION...BORGHOFF
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
1152 PM CST SUN DEC 22 2013 .UPDATE... ISSUED AT 945 PM CST SUN DEC 22 2013 HAVING A HARD TIME KEEPING UP WITH THE BITTER COLD TEMPERATURES ACROSS WESTERN MINNESOTA THIS EVENING. THE -10F ISOTHERM IS BEGINNING TO INCH INTO WESTERN MN...WITH WIND CHILLS IN THE -30S. THE RAP AND HOPWRF MODELS ARE SHOWING WIDESPREAD -20S FOR AIR TEMPERATURES IN THOSE AREAS LATE TONIGHT...WITH WIND REMAINING IN THE 10-15 MPH RANGE. SINCE IT IS SO CLOSE TO WARNING CRITERIA ALREADY BEFORE 10 PM...UPGRADED MOST OF WESTERN MN AND THE MN RIVER VALLEY TO A WIND CHILL WARNING. IN ADDITION...HIGHS TOMORROW WILL STRUGGLE TO GET MUCH ABOVE 10 BELOW IN THESE AREAS AND WIND CHILLS WILL CONTINUE TO BE IN THE -30S FOR MOST OF THE DAY. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 221 PM CST SUN DEC 22 2013 LIGHT SNOW WILL PERSIST ACROSS THE EASTERN CWA FOR MUCH OF THE PERIOD...WITH COLD AIR ADVECTION SPREADING ACROSS THE SOUTHWESTERN PART OF THE CWA. EARLY AFTERNOON WATER VAPOR IMAGERY TOGETHER WITH 500MB HEIGHTS AND WINDS SHOWS A HIGH AMPLITUDE TROUGH ACROSS CENTRAL NORTH AMERICA...WITH A NORTH/SOUTH ORIENTED JET OVER THE EASTERN SPINE OF THE ROCKIES. AN AREA OF POSITIVE VORTICITY OWING TO THE SPEED SHEAR ON THE POLEWARD SIDE OF THIS JET WILL CONTINUE TO ROTATE ACROSS THE UPPER MIDWEST. 500M HEIGHT FALLS WILL CONTINUE AHEAD OF THIS WAVE ACROSS NORTHERN MN/WI...RESULTING IN AN INVERTED TROUGH AND PERIODS OF LIGHT SNOW. NORTHWEST WINDS WILL INCREASE TO AROUND 20MPH AND CONTINUE OVERNIGHT. THEREFORE HAVE KEPT LOW TEMPERATURES SLIGHTLY ABOVE GUIDANCE...FAVORING THE SCENARIO OF STRONGER WINDS AND SLIGHTLY WARMER TEMPERATURES...AS OPPOSED TO WEAKER WINDS AND LOWER TEMPS. EITHER RESULT STILL PRODUCES WIND CHILL VALUES LESS THAN 25 BELOW ZERO ACROSS MOST OF THE WESTERN CWA...WHICH WILL REBOUND SLIGHTLY MONDAY AFTERNOON...BUT FALL OFF AGAIN MONDAY NIGHT. FOR SIMPLICITY/S SAKE...HAVE GONE WITH ONE LONG WIND CHILL ADVISORY THROUGH TUESDAY MORNING. THIS WILL LIKELY NEED TO BE EXPANDED FARTHER EAST...AND PERHAPS UPGRADED TO A WARNING ACROSS THE NORTHWEST MONDAY NIGHT. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 221 PM CST SUN DEC 22 2013 GENERALLY COLD NORTHWEST UPPER FLOW WILL PREDOMINATE THROUGH THE LONG TERM... WITH PERIODIC CLIPPERS AND REINFORCING SHOTS OF COLD AIR. THE MAIN FEATURE OF INTEREST WILL BE A SHORTWAVE CURRENTLY SOUTH OF ALASKA WHICH WILL MOVE THROUGH THE REGION TUESDAY AFTERNOON AND EVENING... BRINGING A DECENT SHOT OF LIGHT SNOW TO THE AREA. THE GFS... NAM... AND ECMWF ARE GENERALLY IN GOOD AGREEMENT ON THE SYSTEM... WITH SOME DIFFERENCES IN TIMING AND LOCATION OF THE HEAVIEST PCPN. THE THALER-QC DIAGNOSTICS FROM THE RESPECTIVE MODELS SHOW PCPN TOTALS QUITE SIMILAR TO WHAT IS COMING DIRECTLY FROM THE MODELS... AND LOCAL LATENT HEAT DEPRIVATION SENSITIVITY RUNS SHOW MINIMAL DIFFERENCE IN SOLUTIONS. ALL OF THIS POINTS TOWARD HIGH CONFIDENCE OF A 6 HOUR OR SO WINDOW OF LIGHT TO MODERATE SNOWFALL. WITH LIQUID PCPN RUNNING FROM A TENTH TO AROUND A QUARTER OF AN INCH... WOULD EXPECT TO SEE TOTALS GENERALLY IN A RANGE FROM 1 TO 3 INCHES. MIXING RATIOS OF 2-2.5 G/KG ARE PRESENT ON THE 290K SURFACE... WHICH WOULD EQUATE TO AROUND 5 INCHES IN 12 HOURS WITH THE IMR METHOD... SO 2.5 INCHES IS PROBABLY ABOUT RIGHT FOR MOST SPOTS. OF COURSE... MUCH WILL DEPEND ON RATIOS... SO IF WE SEE RATIOS GET UP NEAR 25 TO 1... THEN WE COULD SEE SOME LOCALIZED TOTALS TO 4 OR EVEN 5 INCHES. THE FORECAST SOUNDINGS DO SUGGEST A DECENT DEPTH OF -12 TO -18 C TEMPERATURES IN THE SATURATED PORTION OF THE PROFILE... SO THE RATIO ISSUE WILL CERTAINLY NEED TO BE MONITORED. EVEN WITH ONLY A LIGHT SNOW EXPECTED... IT COULD BE IMPACTFUL GIVEN THAT IT WILL OCCUR DURING THE LATE AFTERNOON AND EVENING HOURS ON CHRISTMAS EVE... SO IT IS SOMETHING TRAVELERS WILL NEED TO CONSIDER WHEN MAKING PLANS. ON CHRISTMAS DAY WE SHOULD EVENTUALLY SEE WEST WINDS PICK UP AND SHIFT TO THE NORTHWEST LATER IN THE DAY. THE STRONGEST WINDS SHOULD IMPACT WEST CENTRAL AND SOUTHERN PORTIONS OF THE AREA... WHICH COULD LEAD TO BLOWING/DRIFTING SNOW ISSUES... WHICH WILL BE AN ADDITIONAL CONCERN FOR TRAVELERS ON CHRISTMAS DAY. THE OTHER ISSUE OF CONCERN WILL BE VERY COLD TEMPERATURES AND WIND CHILLS MONDAY NIGHT INTO TUESDAY MORNING... WITH THE SURFACE RIDGE SETTLING OVER THE AREA AND A COATING OF FRESH SNOW THANKS TO WHAT WE/RE SEEING TODAY INTO MONDAY. THE ENTIRE AREA WILL GET WELL BELOW ZERO... WITH READINGS OF 20 TO 25 BELOW LIKELY OVER PORTIONS OF THE WEST/NORTHWEST FORECAST AREA. EVEN THE TWIN CITIES METRO SHOULD SEE READINGS TO NEAR 15 BELOW. THE ONLY AREA WHICH WILL ESCAPE THE WORST OF THE COLD WILL BE EAST OF I-35 WHERE CLOUDS LOOK TO HANG ON FOR AT LEAST HALF OF MONDAY NIGHT BEFORE RIDGING IS SUFFICIENT TO SCOUR THEM OUT. ALTHOUGH WINDS WILL BE LIGHT... EVEN THE SLIGHT ZEPHYR EXPECTED WILL RESULT IN WIND CHILLS A GOOD 10 TO 15 DEGREES LOWER THAN TEMPERATURES... MEANING SOME LOCATIONS IN THE NORTHWEST PORTION OF THE AREA COULD SEE WIND CHILLS NEAR 40 BELOW BY 6 AM TUESDAY. DECIDED TO EXTEND THE EXISTING WIND CHILL ADVISORY THROUGH TUESDAY MORNING FOR NOW... SINCE ADVISORY CRITERIA ARE PRETTY MUCH ASSURED. LATER SHIFTS CAN LOOK INTO PERHAPS GOING WITH WIND CHILL WARNINGS FOR A PORTION OF THE AREA FOR LATE MONDAY NIGHT INTO TUESDAY MORNING. WE WILL LIKELY KEEP SOME SNOW SHOWERS/FLURRIES AROUND ON CHRISTMAS DAY AS CYCLONIC FLOW LINGERS... BUT THE MAIN ISSUE IF ANY WILL BE BLOWING/DRIFTING SNOW AS MENTIONED ABOVE. RIDGING LOOKS TO WORK IN WEDNESDAY NIGHT THROUGH THURSDAY... WITH COLD AND DRY CONDITIONS ACROSS THE AREA. NORTHERN PORTIONS OF THE AREA COULD SEE SOME LIGHT SNOW CHANCES AGAIN OVER THE UPCOMING WEEKEND AS WE SEE A FEW BRIEF WARM-UPS AND SUBSEQUENT COOL-DOWNS AS CLIPPERS DROP SOUTHEAST/EAST IN THE NORTHWEST UPPER FLOW ALONG THE CANADIAN BORDER. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1137 PM CST SUN DEC 22 2013 MVFR CONDITIONS EXPECTED TO PERSIST FOR MUCH OF THE OVERNIGHT AND INTO MONDAY ACROSS CENTRAL/EASTERN MN AND WESTERN WI. MAINLY VFR AT AXN AND RWF AS THESE SITES REMAIN ON THE WESTERN PERIPHERY OF THE SYSTEM GENERATING SNOW TO THE EAST. DRIER AIR WILL FINALLY PUSH INTO THE REST OF THE TAF SITES LATE MONDAY. NORTHWEST WINDS AROUND 10 KTS WILL PERSIST THROUGH MONDAY...BECOMING LIGHT AND VARIABLE MONDAY EVENING. KMSP...MVFR CONDITIONS THROUGH MOST OF MONDAY IN LIGHT SNOW...WITH VFR CONDITIONS BY MID AFTERNOON. SNOW ACCUMULATIONS WILL REMAIN AROUND AN INCH OR LESS. /OUTLOOK FOR KMSP/ TUE...VFR WITH MVFR/IFR AND -SN BY AFTN. WINDS S AT 10G20KTS. WED...MVFR WITH -SN/BLSN POSSIBLE. WINDS W AT 15G25KTS. THU...VFR. WINDS W AT 10KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR MNZ042-043- 049>051-058-059-066>069-076-077-084-085-091>093. WIND CHILL WARNING UNTIL NOON CST TUESDAY FOR MNZ041-047-048- 054>057-064-065-073>075-082-083. WI...NONE. && $$ UPDATE...BORGHOFF SHORT TERM...TRH LONG TERM...JRB AVIATION...BORGHOFF
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
840 PM MST TUE DEC 24 2013 .UPDATE... ONLY MINOR CHANGES ARE IN THE WORKS FOR THE OVERNIGHT FORECAST. WE WILL ACTUALLY INCREASE EXPECTED LOWS A BIT IN MANY AREAS SINCE THE WESTERLY LOW-LEVEL FLOW MAY KEEP ENOUGH TURBULENT LOW-LEVEL MIXING GOING TO NEGATE ANY BIG FALLS...ESPECIALLY SINCE SNOWMELT HAS BEEN OCCURRING TODAY. ONE EXCEPTION WILL BE AROUND SHERIDAN...WHERE THE WINDS WILL BE LIGHT...AND THUS TEMPERATURES SHOULD FALL AS PLANNED ONCE CLOUDS DECREASE A BIT. OTHERWISE...ONLY SMALL ADJUSTMENTS ARE BEING MADE TO THE GRIDDED FORECAST. SCHULTZ && .SHORT TERM...VALID FOR WED AND THU... BIGGEST CONCERN FOR THIS FORECAST PACKAGE WILL BE WINDS. NORTHWEST FLOW WILL BE PRESENT OVER THE AREA BUT THE SHORTWAVES THAT MOVES THROUGH WILL BE WEAK AND THE ATMOSPHERE IS NOT EXPECTED TO BE OVERLY MOIST. SO WILL LEAVE POPS OUT. TEMPERATURES WILL BE MILD WITH 850MB TEMPERATURES ABOVE ZERO. NOW TO WINDS. WINDS HAVE INCREASED FROM BIG TIMBER TO HARLOWTON THIS AFTERNOON WITH SOME GUSTS TO 50 MPH. GRADIENT HAS TIGHTENED UP BUT WAS NOT OVERLY TIGHT. MODELS SLACKEN THE GRADIENT SOME TONIGHT AND WOULD THUS EXPECT THE WINDS TO DECREASE SOME. THE HRRR MODEL DID GRAB ONTO THESE STRONGER WINDS THIS AFTERNOON AND DECREASES THE WINDS THIS EVENING. SO WILL NOT ISSUE ANY HIGHLIGHTS AT THIS TIME. THE GRADIENT TIGHTENS UP FURTHER WEDNESDAY NIGHT AND TURNS MORE PERPENDICULAR TO THE UPPER YELLOWSTONE AND UPPER STILLWATER RIVER VALLEYS. THIS WILL CAUSE SOUTHWEST WINDS TO CRANK UP AGAIN AT LIVINGSTON AND NYE. HAVE BUMPED WINDS UP INTO ADVISORY CRITERIA. WILL NOT ISSUE WIND HIGHLIGHTS FOR THIS YET AS WOULD LIKE TO SEE SOME MODEL AND GUIDANCE PERSISTENCE ON THIS EVENT. WILL ISSUE A HWO AND PUT A GRAPHIC ON THE WEB PAGE FOR THE WINDS. TWH .LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE... MODELS REMAIN GOOD AGREEMENT THROUGH THE EXTENDED PERIOD. A FAST NORTHWEST FLOW ALOFT WILL BE OVER THE FORECAST AREA THROUGH THE MAJORITY OF THE PERIOD AS A HIGH PRESSURE RIDGE AXIS WILL REMAIN OVER THE PACIFIC NORTHWEST. FRIDAY...HIGH PRESSURE RIDGING AND RISING HEIGHTS WILL BE OVER THE FORECAST AREA RESULTING IN DRY CONDITIONS AND ABOVE NORMAL TEMPERATURES. SURFACE LOW PRESSURE ACROSS SOUTHERN CANADA COMBINED WITH HIGH PRESSURE ACROSS IDAHO WILL SET UP LEE-SIDE TROUGHING ACROSS OUR AREA RESULTING IN CONTINUED WINDY CONDITIONS FOR THE BEARTOOTH/ABSAROKA FOOTHILLS LOCATIONS. ANOTHER FAST MOVING DISTURBANCE...AN ALBERTA CLIPPER SYSTEM...WILL DROP SOUTHEAST OUT OF CANADA LATE FRIDAY NIGHT INTO SATURDAY NIGHT BRINGING ANOTHER ARCTIC FRONT AND A GOOD CHANCE FOR SNOW ACROSS THE AREA ESPECIALLY SATURDAY AFTERNOON AND EVENING. DYNAMICS ARE DECENT WITH THIS SYSTEM AND MODELS SHOW A GOOD FRONTOGENESIS BAND ACROSS THE AREA ESPECIALLY THE BEARTOOTH/ABSAROKA FOOTHILLS AREA. ALTHOUGH LATEST MODELS HAVE SHOWN THIS SYSTEM TO BE WEAKENING A BIT. HOWEVER...GIVEN UNSTABLE NORTHWEST FLOW ALOFT...CAN NOT RULE OUT THIS SYSTEM BEING STRONGER THAN WHAT MODELS CURRENTLY SHOW. 850MB TEMPERATURES ARE A BIT WARMER BUT STILL AROUND -15C BY SUNDAY MORNING. AS A RESULT...EXPECT LOWS SUNDAY MORNING IN THE SINGLE DIGITS AND TEENS WITH HIGHS SUNDAY IN THE 20S WEST WITH TEENS ACROSS THE EAST. WEAK DOWNSLOPE FLOW RETURNS FOR MONDAY MODERATING TEMPERATURES BACK CLOSER TO NORMAL. HOOLEY && .AVIATION... SKIES WILL BE CLEAR TO PARTLY CLOUDY THROUGHOUT THE NIGHT WITH VFR CONDITIONS PREVAILING. NO SIGNIFICANT AVIATION HAZARDS ARE EXPECTED. WINDS ARE EXPECTED TO INCREASE AGAIN AT KLVM WEDNESDAY. BT && .PRELIMINARY POINT TEMP/POPS... WED THU FRI SAT SUN MON TUE ----------------------------------------------------------- BIL 020/041 025/045 031/046 028/036 017/024 014/034 019/035 00/N 10/N 00/N 02/J 32/J 21/B 11/B LVM 021/041 026/046 032/047 025/035 014/025 015/034 022/035 00/N 10/N 00/N 12/J 23/J 21/N 11/B HDN 017/036 011/044 018/045 024/034 011/022 007/032 010/033 00/N 10/N 00/U 02/J 32/J 21/B 11/B MLS 016/031 013/039 023/041 023/030 007/015 901/027 003/028 00/B 10/B 00/U 12/J 32/J 21/E 12/J 4BQ 015/033 014/042 023/044 023/033 008/019 001/029 006/032 10/B 10/B 00/U 02/J 32/J 21/B 11/B BHK 015/030 011/038 022/040 022/027 003/016 903/022 005/025 10/B 10/B 00/B 12/J 32/J 21/E 22/J SHR 012/037 015/046 021/046 023/036 013/022 008/034 013/035 00/B 00/B 00/U 02/J 32/J 21/B 11/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
243 PM EST MON DEC 23 2013 .SYNOPSIS... A SLOW MOVING COLD FRONT APPROACHING FROM THE WEST WILL MOVE OFF THE COAST TONIGHT. DRIER AND COOLER AIR WILL SPREAD ACROSS THE REGION IN THE WAKE OF THE COLD FRONT. A MOSTLY DRY COLD FRONT WILL PASS ACROSS THE AREA FRIDAY...MAINTAINING SEASONABLE TEMPERATURES INTO THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 240 PM MONDAY...THE COLD FRONT CONTINUES TO PRESS EASTWARD AS IT IS APPROACHES RALEIGH BUT IS IT STILL LAGS A BIT TO THE SOUTH. A POSSIBLE PREFRONTAL TROUGH IS RUNNING AHEAD OF THE FRONT TO THE SOUTH. THE 18Z UTC RUC IS SHOWING THE 850 LOW LEVEL JET MAX CENTERED OVER SOUTH CAROLINA AND THIS FEATURE WILL SHIFT NORTH OUT OF THE AREA BY 22 UTC. THIS APPEARS TO BE THE WHAT IS ENHANCING THE LOW TOP CONVECTION IN INLAND AREAS OF SOUTHEAST NORTH CAROLINA. SEA FOG IS NOW BREAKING UP ALONG THE GEORGETOWN COAST AND WILL LINGER FOR THE NEXT HALF HOUR BEFORE BECOMING A NONE FACTOR. MODELS STILL CONTINUE TO BRING A FRONT TO THE COAST BY 7 PM BUT THE MODELS MAINTAIN A GOOD CHANCE OF SHOWERS EARLY THEN SLOWLY TAPER THE RAIN OFF OVERNIGHT. QPF VALUES APPEAR TO BE LESS THAN A HALF OF AN INCH. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 240 PM MONDAY...A DRIER COLUMN WILL BUILD ACROSS THE AREA EARLY ON IN THE SHORT TERM PERIOD AS THE SUBTROPICAL MOISTURE PLUME SHIFTS AWAY FROM THE COAST. LINGERING LOW CLOUDS IN THE MORNING...BUT RAINFALL WILL COME TO AN END WITH THE DEPARTURE OF THE AFOREMENTIONED PLUME AND AS STRONG SUBSIDENCE DEVELOPS IN THE H85-H5 LAYER. THUS THE TREND FOR TUESDAY IS CLEARING SKIES AND MUCH COOLER TEMPERATURES COMPARED TO THE RECENT WARM SPELL. COLDER AIR ARRIVES TUESDAY NIGHT INTO WEDNESDAY MORNING (LOWS IN THE MID TO UPPER 20S) WITH COLD AIR ADVECTION LEADING TO HIGHS ONLY IN THE 40S FOR CHRISTMAS DAY. INCREASING CLOUDS WEDNESDAY NIGHT WILL RESULT IN SLIGHTLY WARMER MINS...BUT THEY WILL STILL BE AT OR JUST BELOW FREEZING ACROSS THE FORECAST AREA. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 240 PM MONDAY...THE EXTENDED FORECAST CONTINUES TO LOOK RATHER UNEVENTFUL WITH THE OVERALL MID LEVEL PATTERN DEPICTING A MODEST TROUGH OVER THE EASTERN THIRD OF THE U.S. AND MODEST RIDGING ACROSS THE SOUTHWEST. AT THE SURFACE THERE WILL BE TWO FRONTS THAT MOVE ACROSS THE AREA THAT WILL ONLY SERVE TO RESET ANY TEMPERATURE MODIFICATION. TEMPERATURES THURSDAY AND FRIDAY WILL BE SLIGHTLY BELOW CLIMATOLOGY AS THE COLD AIR MASS THAT FOLLOWS THE SYSTEM MOVING THROUGH TODAY AND TONIGHT LINGERS. THERE IS A SLIGHT MODIFICATION OF TEMPERATURES SATURDAY AND SUNDAY VIA AIRMASS MODIFICATION. THIS BRIEF WARMUP IS SHORT LIVED AS ANOTHER DRY FRONT MOVES ACROSS MONDAY. THE TRENDS ARE RATHER CONSISTENT AND THE CONSOLATION IS THAT THE WILD TEMPERATURE SWINGS WE HAVE EXPERIENCED THE PAST FEW WEEKS ARE AT LEAST TEMPORARILY A THING OF THE PAST. FINALLY THE ONLY POPS IN THE FORECAST ARE THURSDAY INTO EARLY FRIDAY FROM WHAT APPEARS TO BE MORE OF A WEAK WAVE MOVING IN FROM THE SOUTHWEST FLOW ALOFT THAT SKIRTS THE AREA. THE SURFACE COASTAL TROUGH PATTERN SEEMS TO HAVE DISAPPEARED. REGARDLESS OF THE FORCING MECHANISMS...POPS REMAIN LOW AND MOSTLY CONFINED TO THE COASTAL AREAS. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 18Z...STUBBORN SEA FOG MAY HANG ON AT CRE FOR THE FIRST HOUR OR SO...OTHERWISE LOOK FOR MAINLY MVFR CONDITIONS THIS AFTERNOON. FRONTAL BOUNDARY WILL PASS THROUGH THE WESTERN TERMINALS BY LATE AFTERNOON...REACHING THE COAST AROUND 00-02Z. WINDS WILL SHIFT TO THE NORTH BEHIND THE FRONT...WITH LIGHT RAIN OR DRIZZLE EXPECTED...ALONG WITH LOWERING CEILINGS. MOST OF THE OVERNIGHT HOURS WILL BE IFR...LINGERING INTO THE DAYLIGHT HOURS ALONG THE COAST TUESDAY. LOOK FOR CONDITIONS TO IMPROVE TO NEAR VFR TOWARD THE END OF THE FORECAST PERIOD...IMPROVING FROM WEST TO EAST. EXTENDED OUTLOOK...VFR THROUGH THE PERIOD. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 240 PM MONDAY...THE DENSE FOG ADVISORY WILL BE ALLOWED TO EXPIRE AT 3 PM AS IT CONTINUE TO SLOWLY DISSIPATE AND ADVECT TO THE NORTH NORTHEAST AHEAD OF A SLOW MOVING FRONT FOR THE WATERS MAINLY SOUTH OF LITTLE RIVER INLET. THE FRONTAL PASSAGE ACROSS THE WATERS IS EXPECTED AFTER 7 PM AND WITH THIS FRONT A GOOD PUSH OF OFFSHORE FLOW IS EXPECTED AND THE SEAS WILL FALL BELOW SMALL CRAFT CONDITIONS AT 8 PM SOUTH OF LITTLE RIVER INLET AND 2 AM FOR THE WATERS TO THE NORTH. SEAS SHOULD RELAX LATE AND WILL BEGIN AT 4 TO 6 FEET BUT WILL SETTLE OUT TO A RANGE OF 2 FEET NEAR SHORE AND 5 FEET AT 20 MILES OFF THE COAST. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 240 PM MONDAY...N TO NW FLOW WILL PREVAIL IN THE WAKE OF THE COLD FRONT TUESDAY AND TUESDAY NIGHT...THEN THE WIND WILL VEER TO THE NE DURING WEDNESDAY. WINDS WILL DIMINISH TO AROUND 10 KT OR LESS BY WEDNESDAY NIGHT AS WEAKENING RIDGE OF HIGH PRESSURE BUILD INTO THE VICINITY. THE OFFSHORE TRAJECTORY WILL RESULT IN A RANGE OF SEAS THAT WILL BE FETCH LIMITED NEAR THE COAST. FOR THE MOST PART SEAS WILL APPROACH 5 FT CLOSER TO 20 NM OFFSHORE THROUGH MOST OF THE PERIOD WITH 1-2 FT SEAS NEAR THE COAST. LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 240 PM MONDAY...ONCE AGAIN THE CENTRAL THEME FOR THE EXTENDED COASTAL WATERS FORECAST IS A NORTHERLY COMPONENT TO THE WINDS. FOR THURSDAY THE FLOW WILL BE 10-15 KNOTS WITH A COUPLE OF ROGUE GUSTS OVER 15 POSSIBLE. AS A DRY FRONT MOVES ACROSS FRIDAY SPEEDS WILL INCREASE TO 15-20 KNOTS. SATURDAY WINDS DROP BACK DOWN TO 10-15 KNOTS...AGAIN FROM THE NORTH. SEAS WILL FOLLOW THE WIND SPEED TRENDS WITH 2-4 FEET THURSDAY AND SATURDAY WITH 3-5 FEET FOR FRIDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...DENSE FOG ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR AMZ254- 256. SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR AMZ254- 256. SMALL CRAFT ADVISORY UNTIL 2 AM EST TUESDAY FOR AMZ250-252. && $$ NEAR TERM...DRH SHORT TERM...SRP LONG TERM...SHK AVIATION...DL/DRH
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
646 PM EST TUE DEC 24 2013 .SYNOPSIS... HIGH PRESSURE FROM THE CENTRAL LAKES TO THE LOWER OHIO VALLEY WILL MOVE TO THE MIDDLE ATLANTIC STATES ON CHRISTMAS DAY. A COLD FRONT WILL MOVE EAST ACROSS THE AREA THURSDAY. HIGH PRESSURE WILL BUILD OVER THE REGION THURSDAY NIGHT. THE HIGH PRESSURE AREA WILL DRIFT SOUTH TO THE TENNESSEE VALLEY BY SATURDAY AND ALLOW FOR MODERATING TEMPERATURES. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... LAKE EFFECT SNOW CONTINUES TO DECREASE IN COVERAGE BUT IT APPEARS IT WILL KEEP ACCUMULATING IN THE ADVISORY AND WARNING AREAS THROUGH AROUND 03Z. ADDITIONAL AMOUNTS SHOULD BE UNDER AN INCH. A FEW FLURRIES WILL THEN LINGER UNTIL AROUND 06Z. STILL APPEARS THAT WE WILL BE ABLE TO LET THE HEADLINES END AT 10 PM. OTHERWISE WE WILL CONTINUE TO MONITOR THE THINNING OF THE CLOUD COVER ACROSS NORTHERN OHIO. HOW LONG A PERIOD OF PARTLY CLOUDY SKIES WILL HAVE A HUGE IMPACT ON LOW TEMPERATURES BEFORE HIGH CLOUDS RETURN TO THE WEST AFTER MIDNIGHT. PREVIOUS DISCUSSION... LAKE EFFECT SNOWS ARE WINDING DOWN THIS AFTERNOON AS THE UPPER TROUGH MOVES EAST THE AREA AND THE INVERSION LOWERS ACROSS THE REGION. THE FLOW HAS VEERED TO NORTHWEST DECREASING THE FETCH ACROSS LAKE ERIE. VISIBLE IMAGERY SHOWS CUMULUS CLOUDS GRADUALLY CLEARING OVER THE WESTERN SECTION OF THE LAKE. LAKE EFFECT BANDS SHOULD CONTINUE TO DIMINISH. ONE TO TWO MORE INCHES OF SNOW ARE POSSIBLE THIS EVENING OVER FAR NE OHIO AND NW PA SO WILL CONTINUE THE LAKE EFFECT HEADLINES WITH NO CHANGES. WILL KEEP LIKELY POPS IN NW PA FOR THIS EVENING WITH DRY CONDITIONS OVER THE WESTERN 2/3 OF THE FORECAST AREA. WITH FRESH SNOW COVER EAST OF CLE AND SOME CLEARING EXPECTED ALONG WITH LIGHT WINDS...SOME RADIATIONAL COOLING IS EXPECTED ESPECIALLY IN GEAUGA COUNTY. THE HRRR MODEL SURFACE TEMPERATURES DROP INTO THE SINGLE DIGITS IN THIS AREA AND THIS SEEMS VERY REASONABLE. ELSEWHERE SLIGHTLY WARMER CONDITIONS ARE EXPECTED GIVEN SLIGHTLY MORE WIND AND EITHER SLOWER CLEARING THIS EVENING OR AN INCREASE IN CLOUDS AFTER MIDNIGHT. STILL READING WILL BE RATHER COLD AND BE AROUND 10. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY NIGHT/... ANOTHER SHORT WAVE WILL MOVE EAST ACROSS THE GREAT LAKES CHRISTMAS DAY AND PRODUCE MODEST ISENTROPIC LIFT ACROSS THE AREA. THE AIRMASS IS QUITE DRY SO LITTLE SNOWFALL IS EXPECTED AND WILL BE MAINLY NEAR LAKE ERIE WITH LITTLE MORE THAN A DUSTING. TEMPERATURES WILL MODERATE TO THE MID TO UPPER 20S. ANOTHER IMPULSE WILL DEEPEN THE TROUGH WEDNESDAY EVENING AND EARLY THURSDAY WITH A COLD FRONTAL PASSAGE TOWARD MORNING. THE LOW LEVEL FLOW VEERS TO A MORE WESTERLY DIRECTION WITH 850 MB TEMPERATURES COOLING TO NEAR -12C SO SOME LAKE EFFECT/ENHANCED SNOW IS EXPECTED IN THE SNOWBELT THURSDAY. THE FLOW WILL BACK TO A SOUTHWESTERLY DIRECTION THURSDAY NIGHT ALONG WITH WARMING CONDITIONS SO ANY LAKE EFFECT SNOWBANDS WILL SHIFT OFFSHORE AND DIMINISH. FAIR MODERATING CONDITIONS ARE EXPECTED FRIDAY AS 850 MB TEMPERATURES WARM TO NEAR 0C AS A SOUTHWESTERLY FLOW DEVELOPS. && .LONG TERM /SATURDAY THROUGH TUESDAY/... DRY WEATHER IS EXPECTED ON SATURDAY AS A FRONT APPROACHES FOR SUNDAY. THE AMOUNT OF MOISTURE ASSOCIATED WITH THE FRONT IS NOT THAT IMPRESSIVE SO WILL CONTINUE CHANCE POPS ON SUNDAY INTO SUNDAY NIGHT. PRECIPITATION TYPE IS IN QUESTION. THE ECMWF IS A LITTLE WARMER...SO WILL MENTION A MIX FOR SUNDAY. FOR SUNDAY NIGHT IT WILL BE COLD ENOUGH JUST FOR SNOW SHOWERS. SNOW SHOWERS WILL LINGER INTO MONDAY NIGHT...LOW CHANCE WITH MOISTURE LIMITED EVEN THOUGH THE LAKE AND 850 MB TEMPERATURE DIFFERENCE WILL BE NEAR 20C. ANOTHER FRONTAL SYSTEM WILL BE MOVING IN ON TUESDAY. SOME TIMING QUESTIONS WITH THAT...SO WILL LEAVE THE POPS LOW FOR THE TIME BEING. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... HIGH PRESSURE MOVING OVER THE AREA THRU MIDNIGHT WILL HELP TO END THE LAKE EFFECT SHSN AROUND ERI WHILE THE MVFR STRATO CU OVER ALL BUT THE WESTERN AREA WILL RECEDE TO THE EAST. HIGH AND MID LEVEL CLOUDS WILL SPREAD BACK IN FROM THE WEST LATER TONIGHT THRU MIDDAY WED. SOME LIGHT SHSN MAY BE SPREADING ACROSS THE AREA AROUND AND NEAR LERI BY LATE IN THE DAY WED BUT SINCE THE OVERALL POP FOR ANYTHING MEASURABLE IS ONLY 30% WILL JUST CARRY 6SM SHSN OR VCSH IN TAFS LATE WED AFTERNOON. .OUTLOOK...NON VFR POSSIBLE WEDNESDAY NIGHT AND THURSDAY IN SNOW SHOWERS. && .MARINE... SMALL CRAFT ADVISORIES WILL BE NEEDED FREQUENTLY INTO EARLY NEXT WEEK...ESPECIALLY ON THE EAST END OF THE LAKE. A RIDGE IS BUILDING IN TONIGHT...SO THE WINDS AND WAVES WILL CONTINUE TO DECREASE. WILL LET THE SMALL CRAFT ADVISORY EXPIRE AT 9 PM ON THE EAST END...IT WILL BE CLOSE. THE NEXT THREAT FOR A SMALL CRAFT ADVISORY WILL BE LATE WEDNESDAY NIGHT INTO THURSDAY AFTER ANOTHER FRONT MOVES THROUGH. ANOTHER FRONT MOVES THROUGH LATE FRIDAY AND SATURDAY NIGHT INTO SUNDAY. THIS FRONT WILL PROMPT THE NEED FOR A SMALL CRAFT ADVISORY THAT MAY LAST INTO EARLY NEXT WEEK AS THE WEST TO NORTHWEST FLOW WILL BE PERSISTENT. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST THIS EVENING FOR OHZ014-089. PA...LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST THIS EVENING FOR PAZ003. LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR PAZ001-002. MARINE...SMALL CRAFT ADVISORY UNTIL 9 PM EST THIS EVENING FOR LEZ146>149. && $$ SYNOPSIS...LAPLANTE NEAR TERM...LAPLANTE/MULLEN SHORT TERM...LAPLANTE LONG TERM...KIELTYKA AVIATION...ADAMS MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS TULSA OK
1111 PM CST SUN DEC 22 2013 .AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM. FOR THE 6Z TAFS... WIDESPREAD MVFR CEILINGS ARE EXPECTED TO SCATTER OUT FROM THE NORTH OVER THE NEXT FEW HOURS. VFR CONDITIONS WILL THEN PREVAIL AT ALL SITES FOR THE REMAINDER OF THE FORECAST PERIOD. && .PREV DISCUSSION... /ISSUED 935 PM CST SUN DEC 22 2013/ ..UPDATE... DISCUSSION... UPDATED FORECAST WILL INCREASE CLOUD COVER THROUGH EARLY MORNING WITH CLEARING IN LINE WITH LATEST RUC DATA. OVERNIGHT LOWS WERE CONTINUED THOUGH EASTERN LOCATIONS HAVE MORE UNCERTAINTY PENDING OVERNIGHT CLOUD COVER TRENDS. && .TSA WATCHES/WARNINGS/ADVISORIES... OK...NONE. AR...NONE. && $$ AVIATION...06
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
556 PM EST MON DEC 23 2013 .SYNOPSIS... A SLOW-MOVING FRONTAL BOUNDARY ALONG THE EAST COAST WILL PUSH OUT TO SEA TONIGHT. NOTICEABLY COLDER AIR WILL RETURN TO THE AREA BY CHRISTMAS EVE AND CONTINUE INTO THE END OF THE WEEK. ASIDE FROM THE POSSIBILITY OF A COUPLE OF WEAK CLIPPER TYPE SYSTEMS DROPPING OUT OF THE GREAT LAKES...NO SIGNIFICANT STORMS ARE EXPECTED FOR THE UPCOMING WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... WEAK WAVE OF LOW PRES NR VIRGINIA BEACH SLOWING EXIT OF SFC FRONT ALONG THE E COAST THIS EVENING. RAIN CONTINUES TO FALL EARLY THIS EVENING WELL WEST OF THE FRONT IN REGION OF FGEN FORCING BENEATH RIGHT ENTRANCE TO POWERFUL UPPER JET. LATEST RAP OUTPUT CAPTURES THIS FORCING THE THE 8-7H LVL AND IMPLIES THE LAST OF THE RAIN WILL EXIT LANCASTER CO BY 00Z. THE UPPER TROF AXIS IS STILL WELL TO THE WEST AND WILL BE APPROACHING TONIGHT AND TUESDAY. THE DEEP MOISTURE WILL HAVE PUSHED OFF WELL TO THE EAST BY OVERNIGHT...BUT BETWEEN GR LAKES MOISTURE AND THE INCREASE IN UPPER FORCING...IT WILL BE ENOUGH TO TRIGGER SOME SNOW SHOWERS OVER THE AREAS DOWNWIND OF LAKE ERIE INTO NW PA. AT THIS POINT AMOUNTS LOOK TO AVERAGE LESS THAN ADVISORY LEVELS IN MOST AREAS...BUT WOULD NOT BE SURPRISED TO SEE A FEW REPORTS OF 3 INCHES ACROSS THE SNOWBELT OF NW WARREN CO THROUGH LATE TUESDAY. LOWS TONIGHT WILL END THE RECENT SPELL OF VERY MILD WEATHER WITH TEENS AND 20S GETTING BACK VERY CLOSE TO NORMAL. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... THE UPPER TROF WILL PASS BY EARLY TUESDAY AFTERNOON WITH THE ACCOMPANYING POCKET OF COLD AIR ALOFT HELPING SUPPORT FAIRLY WIDESPREAD SNOW SHOWERS AND FLURRIES. THE BEST CHANCE OF SEEING A COATING TO A COUPLE OF INCHES OF NEW SNOW WILL BE OVER THE HIGH TERRAIN OF THE NORTH AND WEST...WITH LITTLE CHANCE FOR A WHITE CHRISTMAS ELSEWHERE. FORCING FOR THE SNOW SHOWERS WILL BE WANING RAPIDLY IN THE AFTERNOON AS A SHORTWAVE UPPER RIDGE HURRIES TO FILL IN BEHIND OUR DEPARTING TROUGH. HIGH TEMPS FROM NEAR 20 IN THE NORTH TO NEAR 49 IN THE SE WILL REPRESENT A RETURN TO BELOW NORMAL TEMPS FOR THE REGION. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... UPPER LEVEL TROFFING WILL PERSIST THROUGH MUCH OF THE LONG TERM PERIOD OVER THE EASTERN TWO THIRDS OF CONUS AS MODERATE TO STRONG NORTHERN STREAM JET STREAM DIRECTS SEVERAL WAVES OF COLD AIR INTO THE NORTHEASTERN U.S. BRIEF PERIOD OF SHORT WAVE RIDGING ON WEDNESDAY WILL SUPPORT STRONG SFC HIGH WITH A PERIOD OF QUIET WEATHER EXPECTED FOR CHRISTMAS DAY. IN GENERA...MOST OF THE LONG TERM PERIOD SHOULD BE RELATIVELY QUIET WEATHER-WISE DESPITE SEVERAL FRONTAL PASSAGES...AS SYSTEMS WILL BE MOISTURE LIMITED AND NOT ABLE TO PRODUCE MUCH PCPN. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... SOME ADJUSTMENTS MADE TO WINDS IN THE 21Z TAF PACKAGE. RAIN HAS MOVED OUT OF THE SE PART OF THE CWA. EARLIER DISCUSSION BELOW. THE LOW IS NEAR NYC AND WILL CONTINUE PULLING AWAY...LEAVING THE REGION IN A COOLER NW FLOW. THIS MEANS LOWER CLOUDS ALONG WITH THE POTENTIAL FOR SNOW SHOWERS OVER THE HIGH TERRAIN OF THE WEST AND NORTHWEST...WITH A RETURN TO VFR AT CENTRAL AND EASTERN TERMINALS. A STRONG UPPER LEVEL TROUGH WILL BE CROSSING THE AIRSPACE LATE TONIGHT AND EARLY TUESDAY HELPING TO ENHANCE LAKE EFFECT/UPSLOPE SNOW SHOWERS ACRS THE WESTERN AND NORTHER HIGH TERRAIN. LIGHT SNOW SHOWERS AND BRIEF REDUCTIONS WILL BE POSSIBLE OVER CENTRAL TERMINALS INTO TUESDAY AFTERNOON WHEN CONDITIONS SHOULD BEGIN IMPROVING OVER ALL BUT NW PA AS A RIDGE OF HIGH PRESSURE BEGINS TO BUILD BACK INTO THE AREA. OUTLOOK... WED...VFR HIGH PRES. THU-FRI...OCNL SNOW SHOWERS/MVFR CIGS WEST. VFR CENTRAL AND EASTERN AREAS. SAT...NO SIG WX. && .CLIMATE... RECORD DAILY MAXIMUM TEMPERATURES WERE SET AT OUR OFFICIAL CLIMATE SITES /HARRISBURG AND WILLIAMSPORT/ YESTERDAY. THERE WERE ALSO SEVERAL "UNOFFICIAL" RECORD HIGHS SET AT NON-LCD SITES SUCH AS ALTOONA AND BRADFORD. A RECORD HIGH TEMPERATURE OF 70 DEGREES WAS SET AT HARRISBURG YESTERDAY. THIS BROKE THE OLD RECORD HIGH OF 64 DEGREES SET BACK IN 1949. A CONTINUOUS WEATHER RECORD HAS BEEN KEPT AT HARRISBURG SINCE 1888. A RECORD HIGH TEMPERATURE OF 64 DEGREES WAS SET AT WILLIAMSPORT YESTERDAY. THIS BROKE THE OLD RECORD OF 60 DEGREES SET BACK IN 1949. A CONTINUOUS WEATHER RECORD HAS BEEN KEPT AT WILLIAMSPORT SINCE 1895. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD/LA CORTE NEAR TERM...FITZGERALD/LA CORTE SHORT TERM...LA CORTE LONG TERM...LAMBERT/GARTNER AVIATION...LA CORTE/MARTIN CLIMATE...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1055 PM CST SUN DEC 22 2013 .UPDATE... ISSUED AT 1007 PM CST SUN DEC 22 2013 TEMPERATURES STILL TRICKY TONIGHT AS CLOUDS ARE IN AND OUT AND WINDS AT TIMES GO LIGHT. HOWEVER...AFTER COORDINATION WITH OFFICES TO MY NORTH...OPTED TO UPGRADE MY NORTHERN AREAS TO WIND CHILL WARNING THROUGH 16Z MONDAY...AS FORECAST WIND CHILLS DROP TO AROUND 35 BELOW OR A LITTLE COLDER FOR AT LEAST A FEW HOURS IN THE MORNING. RAP MODEL SHOWING TEMPS MUCH COLDER THAN OTHER MODELS...AND HESITATE TO GO THAT COLD WITHOUT PRISTINE RADIATIVE CONDITIONS. BUT DID HEDGE IN THAT DIRECTION IN MY NORTHWEST WHERE KHON HAS ALREADY SHOWN TENDENCY TO DROP OFF. UPDATED WSW/ZFP HAS BEEN SENT. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 344 PM CST SUN DEC 22 2013 COLD NIGHT AHEAD ACROSS THE REGION AS ARCTIC HIGH PRESSURE BUILDS INTO THE REGION. WITH COLD CORE SYSTEM BUILDING INTO THE AREA...925 HPA TEMPS WILL FALL TO NEAR -22 C BY TOMORROW MORNING. WITH NORTHWEST FLOW CONTINUING ACROSS THE AREA...WIND CHILL READINGS WILL FALL INTO THE DANGEROUS CATEGORY WITH COLDEST READINGS MONDAY MORNING APPROACHING 35 BELOW ALONG THE HIGHWAY 14 CORRIDOR. TEMPS WILL BE SLOW TO MODERATE ON MONDAY WITH HIGH PRESSURE SLIDING EAST ACROSS THE AREA. HAVE LOWERED FORECAST HIGHS...ESPECIALLY IN THE NORTHEAST PORTION OF THE FORECAST AREA WHERE NORTHWEST FLOW DOMINATES THROUGHOUT THE DAY EAST OF THE RIDGE AXIS. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 344 PM CST SUN DEC 22 2013 RETURN FLOW DEVELOPS ACROSS THE FORECAST AREA MONDAY NIGHT AS THE SURFACE HIGH SLIPS TO THE SOUTHEAST. SOUTHERLY WINDS BECOME BREEZY BY DAYBREAK ACROSS SOUTHEAST SOUTH DAKOTA...WITH A STRONG PUSH OF WARM AIR ADVECTION SPREADING EASTWARD. TEMPERATURES WILL DROP PRETTY QUICKLY IN THE EVENING BEFORE EVENTUALLY WARMING AGAIN IN THE EARLY MORNING HOURS. THIS WILL BE MOST PRONOUNCED IN SOUTH CENTRAL SD WHERE SOUTHERLY WINDS WILL BE STRONGEST. LOWS WILL STILL BE QUITE COLD ESPECIALLY ACROSS OUR NORTHEAST WHERE THE ARCTIC AIRMASS LINGERS. LOWS ARE EXPECTED AS COLD AS THE MID TEENS BELOW ZERO. ALTHOUGH WARMING DOES OCCUR...INCREASING WINDS WILL STILL RESULT IN BRUTAL WIND CHILL VALUES OF 20 TO 35 BELOW ZERO FOR ALL BUT THE MISSOURI VALLEY. HAVE OPTED TO EXTEND THE WIND CHILL ADVISORY IN THIS AREA THROUGH NOON ON TUESDAY WHEN THE MORE SIGNIFICANT WARMING FINALLY BUMPS VALUES OUT OF CRITERIA. WHILE HIGH TEMPERATURES SHOULD IMPROVE TO THE TEENS EAST TO MID 30S IN SOUTH CENTRAL...GUSTY WINDS AROUND 20 TO 30 MPH THROUGH THE DAY WILL STILL FEEL BRISK. MODELS REMAIN IN GOOD AGREEMENT IN DRIVING A FRONTAL BOUNDARY AND SHORTWAVE ACROSS THE NORTHERN PLAINS TUESDAY AFTERNOON AND TUESDAY NIGHT. CONSISTENT WITH THE LAST FEW MODEL RUNS...THIS WAVE IS A BIT MORE ROBUST AND SHOULD BRING A HIGH CHANCE OF SOME LIGHT SNOW THROUGHOUT THE FORECAST AREA. EXPECT SOME LIGHT SNOWFALL TO SPREAD INTO OUR WESTERN BOUNDARY TUESDAY MORNING AND SPREAD EAST THROUGH THE DAY. SNOWFALL POTENTIAL APPEARS TO BE BEST ACROSS THE OUR NORTHERN...CENTRAL AND EASTERN FORECAST AREA WHERE THE MID LEVEL FRONTOGENESIS AND DIV-Q ARE MORE FAVORABLE....NORTH AND EAST OF A LINE FROM AROUND HURON TO SIOUX FALLS TO IDA GROVE. THIS ACTIVITY WILL BE RELATIVELY SHORT LIVED...AND WILL QUICKLY EXIT TO THE EAST LATE TUESDAY EVENING. SNOWFALL AMOUNTS GENERALLY LOOK TO BE A HALF INCH OR LESS IN SOUTH CENTRAL SD...RANGING TO AROUND 2 OR 3 INCHES NEAR THE BUFFALO RIDGE IN SW MN. THE I29 CORRIDOR LOOKS LIKE AROUND 1 TO 2 INCHES. WINDS WILL ONCE AGAIN BECOME BREEZY FROM THE WEST NORTHWEST ON CHRISTMAS BUT WITH MORE OF A WESTERLY COMPONENT AND NOT MUCH OF ANY COLD AIR PUSH BEHIND THE EXITING SYSTEM. THIS WILL KEEP TEMPERATURES COMPARATIVELY MILD AND MUCH CLOSER TO SEASONAL NORMALS...PRIMARILY IN THE LOW 20S TO NEAR 30. COULD SEE ANOTHER WAVE DROP ALONG THE NORTHWEST UPPER LEVEL FLOW AROUND THE WEDNESDAY NIGHT TIME FRAME...HOWEVER THE STRENGTH AND TIMING ARE STILL A BIT UNCERTAIN AT THIS TIME. HAVE DECIDED TO GO AHEAD AND KEEP A MENTION OF A SLIGHT CHANCE OF LIGHT SNOW WED NIGHT IN OUR NORTHEAST...WHERE THE WAVE LOOKS MOST LIKELY TO TRACK. LOOKS LIKE IF ANYTHING THIS WOULD BE A QUICK HALF INCH OR LESS OF SNOWFALL. BIGGEST IMPACT APPEARS TO BE ANOTHER COLD SNAP WITH NEAR ZERO LOWS WEDNESDAY NIGHT AND THURSDAY NIGHT AND HIGHS ON THURSDAY IN THE SINGLE DIGITS AND TEENS ABOVE ZERO. AIRMASS DOES MODERATE AGAIN FOR SATURDAY WITH RETURN FLOW/WARM AIR ADVECTION...BUT THE ROLLER COASTER TEMPERATURE PATTERN USHERS IN YET ANOTHER POTENTIAL COLD AIR PUSH ON SUNDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1055 PM CST SUN DEC 22 2013 VFR CONDITIONS EXPECTED THROUGH THE PERIOD. OCCASIONAL WIND GUSTS OF 15-25KT IN SOUTHWEST MN/NORTHWEST IA THROUGH MID AFTERNOON MONDAY WILL DIMINISH BY SUNSET MONDAY EVENING. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR SDZ056-060>062- 066-067-071. WIND CHILL ADVISORY UNTIL 6 PM CST MONDAY FOR SDZ050-057>059- 063>065-068>070. WIND CHILL WARNING UNTIL 10 AM CST MONDAY FOR SDZ038>040-052>055. WIND CHILL ADVISORY FROM 10 AM MONDAY TO NOON CST TUESDAY FOR SDZ038>040-052>055. MN...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR MNZ080-081-089- 090-097-098. WIND CHILL WARNING UNTIL 10 AM CST MONDAY FOR MNZ071-072. WIND CHILL ADVISORY FROM 10 AM MONDAY TO NOON CST TUESDAY FOR MNZ071-072. IA...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR IAZ001>003- 012>014-020>022-031-032. NE...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR NEZ014. WIND CHILL ADVISORY UNTIL 6 PM CST MONDAY FOR NEZ013. && $$ UPDATE...JH SHORT TERM... LONG TERM... AVIATION...JH
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1007 PM CST SUN DEC 22 2013 .UPDATE... ISSUED AT 1007 PM CST SUN DEC 22 2013 TEMPERATURES STILL TRICKY TONIGHT AS CLOUDS ARE IN AND OUT AND WINDS AT TIMES GO LIGHT. HOWEVER...AFTER COORDINATION WITH OFFICES TO MY NORTH...OPTED TO UPGRADE MY NORTHERN AREAS TO WIND CHILL WARNING THROUGH 16Z MONDAY...AS FORECAST WIND CHILLS DROP TO AROUND 35 BELOW OR A LITTLE COLDER FOR AT LEAST A FEW HOURS IN THE MORNING. RAP MODEL SHOWING TEMPS MUCH COLDER THAN OTHER MODELS...AND HESITATE TO GO THAT COLD WITHOUT PRISTINE RADIATIVE CONDITIONS. BUT DID HEDGE IN THAT DIRECTION IN MY NORTHWEST WHERE KHON HAS ALREADY SHOWN TENDENCY TO DROP OFF. UPDATED WSW/ZFP HAS BEEN SENT. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 344 PM CST SUN DEC 22 2013 COLD NIGHT AHEAD ACROSS THE REGION AS ARCTIC HIGH PRESSURE BUILDS INTO THE REGION. WITH COLD CORE SYSTEM BUILDING INTO THE AREA...925 HPA TEMPS WILL FALL TO NEAR -22 C BY TOMORROW MORNING. WITH NORTHWEST FLOW CONTINUING ACROSS THE AREA...WIND CHILL READINGS WILL FALL INTO THE DANGEROUS CATEGORY WITH COLDEST READINGS MONDAY MORNING APPROACHING 35 BELOW ALONG THE HIGHWAY 14 CORRIDOR. TEMPS WILL BE SLOW TO MODERATE ON MONDAY WITH HIGH PRESSURE SLIDING EAST ACROSS THE AREA. HAVE LOWERED FORECAST HIGHS...ESPECIALLY IN THE NORTHEAST PORTION OF THE FORECAST AREA WHERE NORTHWEST FLOW DOMINATES THROUGHOUT THE DAY EAST OF THE RIDGE AXIS. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 344 PM CST SUN DEC 22 2013 RETURN FLOW DEVELOPS ACROSS THE FORECAST AREA MONDAY NIGHT AS THE SURFACE HIGH SLIPS TO THE SOUTHEAST. SOUTHERLY WINDS BECOME BREEZY BY DAYBREAK ACROSS SOUTHEAST SOUTH DAKOTA...WITH A STRONG PUSH OF WARM AIR ADVECTION SPREADING EASTWARD. TEMPERATURES WILL DROP PRETTY QUICKLY IN THE EVENING BEFORE EVENTUALLY WARMING AGAIN IN THE EARLY MORNING HOURS. THIS WILL BE MOST PRONOUNCED IN SOUTH CENTRAL SD WHERE SOUTHERLY WINDS WILL BE STRONGEST. LOWS WILL STILL BE QUITE COLD ESPECIALLY ACROSS OUR NORTHEAST WHERE THE ARCTIC AIRMASS LINGERS. LOWS ARE EXPECTED AS COLD AS THE MID TEENS BELOW ZERO. ALTHOUGH WARMING DOES OCCUR...INCREASING WINDS WILL STILL RESULT IN BRUTAL WIND CHILL VALUES OF 20 TO 35 BELOW ZERO FOR ALL BUT THE MISSOURI VALLEY. HAVE OPTED TO EXTEND THE WIND CHILL ADVISORY IN THIS AREA THROUGH NOON ON TUESDAY WHEN THE MORE SIGNIFICANT WARMING FINALLY BUMPS VALUES OUT OF CRITERIA. WHILE HIGH TEMPERATURES SHOULD IMPROVE TO THE TEENS EAST TO MID 30S IN SOUTH CENTRAL...GUSTY WINDS AROUND 20 TO 30 MPH THROUGH THE DAY WILL STILL FEEL BRISK. MODELS REMAIN IN GOOD AGREEMENT IN DRIVING A FRONTAL BOUNDARY AND SHORTWAVE ACROSS THE NORTHERN PLAINS TUESDAY AFTERNOON AND TUESDAY NIGHT. CONSISTENT WITH THE LAST FEW MODEL RUNS...THIS WAVE IS A BIT MORE ROBUST AND SHOULD BRING A HIGH CHANCE OF SOME LIGHT SNOW THROUGHOUT THE FORECAST AREA. EXPECT SOME LIGHT SNOWFALL TO SPREAD INTO OUR WESTERN BOUNDARY TUESDAY MORNING AND SPREAD EAST THROUGH THE DAY. SNOWFALL POTENTIAL APPEARS TO BE BEST ACROSS THE OUR NORTHERN...CENTRAL AND EASTERN FORECAST AREA WHERE THE MID LEVEL FRONTOGENESIS AND DIV-Q ARE MORE FAVORABLE....NORTH AND EAST OF A LINE FROM AROUND HURON TO SIOUX FALLS TO IDA GROVE. THIS ACTIVITY WILL BE RELATIVELY SHORT LIVED...AND WILL QUICKLY EXIT TO THE EAST LATE TUESDAY EVENING. SNOWFALL AMOUNTS GENERALLY LOOK TO BE A HALF INCH OR LESS IN SOUTH CENTRAL SD...RANGING TO AROUND 2 OR 3 INCHES NEAR THE BUFFALO RIDGE IN SW MN. THE I29 CORRIDOR LOOKS LIKE AROUND 1 TO 2 INCHES. WINDS WILL ONCE AGAIN BECOME BREEZY FROM THE WEST NORTHWEST ON CHRISTMAS BUT WITH MORE OF A WESTERLY COMPONENT AND NOT MUCH OF ANY COLD AIR PUSH BEHIND THE EXITING SYSTEM. THIS WILL KEEP TEMPERATURES COMPARATIVELY MILD AND MUCH CLOSER TO SEASONAL NORMALS...PRIMARILY IN THE LOW 20S TO NEAR 30. COULD SEE ANOTHER WAVE DROP ALONG THE NORTHWEST UPPER LEVEL FLOW AROUND THE WEDNESDAY NIGHT TIME FRAME...HOWEVER THE STRENGTH AND TIMING ARE STILL A BIT UNCERTAIN AT THIS TIME. HAVE DECIDED TO GO AHEAD AND KEEP A MENTION OF A SLIGHT CHANCE OF LIGHT SNOW WED NIGHT IN OUR NORTHEAST...WHERE THE WAVE LOOKS MOST LIKELY TO TRACK. LOOKS LIKE IF ANYTHING THIS WOULD BE A QUICK HALF INCH OR LESS OF SNOWFALL. BIGGEST IMPACT APPEARS TO BE ANOTHER COLD SNAP WITH NEAR ZERO LOWS WEDNESDAY NIGHT AND THURSDAY NIGHT AND HIGHS ON THURSDAY IN THE SINGLE DIGITS AND TEENS ABOVE ZERO. AIRMASS DOES MODERATE AGAIN FOR SATURDAY WITH RETURN FLOW/WARM AIR ADVECTION...BUT THE ROLLER COASTER TEMPERATURE PATTERN USHERS IN YET ANOTHER POTENTIAL COLD AIR PUSH ON SUNDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 528 PM CST SUN DEC 22 2013 VFR CONDITIONS AND NORTHWEST FLOW WILL CONTINUE THROUGH THE TAF PERIOD WITH ARCTIC AIRMASS ACROSS THE REGION. SPOTTY FLURRIES ARE POSSIBLE FROM 4-6K FOOT STRATUS DECK EAST OF I-29...MAINLY BEFORE 06Z...BUT NOT EXPECTED TO IMPACT TAF LOCATIONS. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR SDZ056-060>062- 066-067-071. WIND CHILL ADVISORY UNTIL 6 PM CST MONDAY FOR SDZ050-057>059- 063>065-068>070. WIND CHILL WARNING UNTIL 10 AM CST MONDAY FOR SDZ038>040-052>055. WIND CHILL ADVISORY FROM 10 AM MONDAY TO NOON CST TUESDAY FOR SDZ038>040-052>055. MN...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR MNZ080-081-089- 090-097-098. WIND CHILL WARNING UNTIL 10 AM CST MONDAY FOR MNZ071-072. WIND CHILL ADVISORY FROM 10 AM MONDAY TO NOON CST TUESDAY FOR MNZ071-072. IA...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR IAZ001>003- 012>014-020>022-031-032. NE...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR NEZ014. WIND CHILL ADVISORY UNTIL 6 PM CST MONDAY FOR NEZ013. && $$ UPDATE...JH SHORT TERM... LONG TERM... AVIATION...JH
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AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
841 PM CST TUE DEC 24 2013 .UPDATE... FORECAST IS LOOKING PRETTY GOOD. NO SIGNIFICANT CHANGES NEEDED YET...BUT WE/RE WATCHING THE CURRENT BACK EDGE TRENDS OVER IOWA. THE HRRR JUST BRINGS THIS LEADING AREA OF WARM AIR ADVECTION PRECIP THROUGH...LASTING JUST A FEW HOURS WITH VERY LITTLE BEHIND IT. THE EARLIER MODELS WERE SUGGESTING MORE REDEVELOPMENT IN THE PERSISTENT WAA FLOW COUPLED WITH THE DECENT SHORT WAVE. FOR A WHILE I THOUGHT THE HRRR WAS GOING TO BE RIGHT...BUT OVER THE LAST HOUR WE ARE SEEING REDEVELOPMENT ACROSS IOWA CAUSING THE PRECIP TO FILL IN AND BECOME ONE LARGER AREA. IT STILL LOOKS LIKE THE SOUTHERN CWA WILL SEE THE LEAST AMOUNT OF SNOW...MAYBE JUST AN INCH OR LESS...WHILE THE NORTH SHOULD BE IN THE 3 INCH RANGE. MADISON TO MILWAUKEE WOULD BE IN THAT 2 INCH RANGE. && .AVIATION/06Z TAFS/... EXPECT MVFR/IFR CIGS/VSBYS DUE TO THE SNOW ROLLING THROUGH THE AREA OVERNIGHT. WE ARE EXPECTING THE SNOW TO TAPER OFF IN THE MADISON AREA AROUND 3 AM...AND IN MILWAUKEE BETWEEN 5 AND 6 AM WEDNESDAY MORNING. STILL LOOKING AT AROUND 2 INCHES AT MILWAUKEE/MADISON/WAUKESHA AND PROBABLY AROUND AN INCH AT KENOSHA. EXPECT MVFR CIGS TO HANG IN AFTER THE SNOW ENDS WITH ANOTHER ROUND OF LIGHT SNOW EXPECTED WEDNESDAY AFTERNOON ASSOCIATED WITH A WEAK MID LEVEL WAVE MOVING THROUGH. ANOTHER INCH OF SNOW ACCUM IS POSSIBLE WITH THIS SECOND ROUND. && .PREV DISCUSSION... /ISSUED 335 PM CST TUE DEC 24 2013/ TONIGHT AND WEDNESDAY - CONFIDENCE...HIGH. IT SHOULD REMAIN DRY INTO EARLY THIS EVENING. SNOW WILL MOVE IN QUICKLY THOUGH MID TO LATE EVENING...AS A STRONG SHORTWAVE APPROACHES. STILL SEEING PRETTY GOOD SATURATION...WITH A FAIRLY DEEP DENDRITE GROWTH ZONE...PARTICULARLY TOWARD THE NORTHEAST. MODELS ALSO SHOWING DECENT LIFT WITH FAIRLY DEEP Q-VECTOR CONVERGENCE. HAVE GENERALLY MAINTAINED THE FORECAST AS IS...WITH HIGH POPS AND 2 TO 3 INCHES OF SNOW EXPECTED BY DAYBREAK CHRISTMAS MORNING. THERE WILL BE A BREAK IN THE SNOW FOR MOST OF THE MORNING TOMORROW...WITH ANOTHER SHORTWAVE BRINGING SOME LIGHT SNOW TO THE FORECAST AREA IN THE AFTERNOON. COULD SEE UPWARDS OF AN INCH BY EARLY EVENING IN SOME SPOTS. IT WILL BE MILDER TOMORROW...THOUGH HIGHS WILL STILL BE A FEW DEGREES BELOW NORMAL. WEDNESDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE...MEDIUM. LINGERING LAYER Q-VECTOR CONVERGENCE AND SLIGHTLY SLOWER MID-LEVEL SHORT WAVE TROUGH EXIT SOUTHEAST WISCONSIN EARLY WEDNESDAY EVENING. MORE CONSISTENT GFS IS SHOWING MORE PRONOUNCED AND SLOWER MOVING MID- LEVEL TROUGH WHILE LATEST NAM MORE PROGRESSIVE WITH FORCING. THINKING -SN WILL BE ONGOING IN THE EARLY EVENING IN THE SOUTHEAST BEFORE ENDING WITH LIGHT ADDITIONAL ACCUMULATIONS. WEAKENING UPSTREAM WARM AIR ADVECTION MAY CARRY SOME FLURRIES BACK INTO SOUTHERN WI LATER WED NGT INTO THU. ANOTHER STRONGER SURGE OF ISENTROPIC UPGLIDE AND LOWERING CONDENSATION PRESSURE DEFICITS MOVES ACROSS SOUTHERN WI THU AFTN AND EVE. HOWEVER LOW TO MID-LEVEL RH APPEARS SPARSE. ENOUGH MOISTURE EXPECTED TO BE IN PLACE AT THIS POINT TO EXPAND SMALL CHANCE FOR LIGHT SNOW ACROSS THE NORTH DURING THIS PERIOD WITH SCATTERED FLURRIES ELSEWHERE. WARMER AIR BEGINS TO RETURN ON FRIDAY WITH DAYTIME TEMPS RETURNING TO THE MID 20S. FRIDAY NIGHT THROUGH TUESDAY...FORECAST CONFIDENCE...MEDIUM. DECREASING TO LOW IN LATER PERIODS. EXTENDED GUIDANCE IN REASONABLE AGREEMENT ON SOME RELAXATION OF COLD NORTHWEST FLOW EARLY IN THE PERIOD...RESULTING IN SOME NOTICEABLE DAYTIME WARMING...MOST NOTICEABLE ON SATURDAY. DAYTIME TEMPS WILL BE WARMER ON FRIDAY BUT BRISK SOUTHWEST WINDS WILL ADD A NOTICEABLE CHILL TO THE AIR. 85H TEMPS WARM TO 6-8C ON SATURDAY. PERSISTENT SPRAWLING HIGH PRESSURE OVER THE SOUTH CENTRAL AND SOUTHEAST CONUS SHOULD PREVENT SIGNIFICANT MOISTURE RETURN AHEAD OF APPROACHING COLD FRONT. THINKING GFS MAY BE OVERDOING AMOUNT OF LOW LEVEL RH ON SATURDAY SO AT LEAST PARTIAL SUNSHINE AND SOUTHWEST BREEZES MAY ALLOW DAYTIME TEMPS TO NEAR FREEZING. COLD FRONT AND WEAKENING SHEARED MID-LEVEL SHORT WAVE MAY HAVE JUST ENOUGH MOISTURE AND OMEGA TO TRIGGER A LIGHT MIXED BAG OF PRECIP SATURDAY NIGHT. FORECAST SOUNDINGS CONTINUE TO SHOW A SMALL CHANCE FOR -ZR/-ZL CHANGING OVER TO -SHSN OR FLURRIES LATER SAT NIGHT INTO SUN AS THE COLD AIR RETURNS. REINFORCING PUSH OF COLD AIR ON SUNDAY MAY CONTRIBUTE TO MORE WIDESPREAD -SN OR -SHSN. EARLY NEXT WEEK...85H TEMPS PLUMMET TO LEVELS EVEN LOWER THAN CURRENT READINGS...FALLING TO 15 TO 20C BELOW BY 12Z/30. WIND CHILLS MAY BECOME AN ISSUE SUNDAY NIGHT AND MONDAY NIGHT. BRISK NORTHWEST FLOW TO PERSIST INTO THE NEW YEAR...HOWEVER GFS AND ECMWF SHOWING INCREASING DISPARITY ON AMOUNT OF MID-LEVEL RIDGING OVER THE NORTHERN PLAINS. ECMWF TRENDING MORE TOWARD POTENTIAL FOR WEAK CLIPPER TYPE SYSTEM POTENTIALLY AFFECTING SRN WI AROUND MON NIGHT. CONSIDERING BRISK NORTHWEST FLOW REGIME...AND WEAKER NEARBY RIDGING...LEANING TOWARD WEAK SNOW PRODUCERS RETURNING AT THIS TIME...AND WL CARRY SOME SMALL POPS IN THE LATE PERIODS. AVIATION/00Z TAFS/... VFR CONDITIONS WILL CONTINUE INTO EARLY THIS EVENING. A STRONG SHORTWAVE WILL THEN BRING SNOW ACROSS THE AREA LATE EVENING AND INTO THE NIGHT. LOOKS LIKE SNOW TOTALS WILL BE IN THE 2 TO 3 INCH RANGE. THIS SNOW WILL LOWER CIGS AND VSBYS. WILL HAVE TO KEEP AN EYE ON UPSTREAM OBS AND FINE TUNE THE TAFS AS THE SNOW APPROACHES. VSBYS SHOULD GO BACK TO VFR FOR A TIME TOMORROW MORNING AS THE SNOW COMES TO AND END...WITH LOWER CLOUDS LIKELY LINGERING. ANOTHER SHORTWAVE WILL BRING SOME LIGHT SNOW LATER IN THE DAY...WITH VISIBILITIES LIKELY GOING BACK DOWN BELOW 6 MILES BY LATE AFTERNOON. COULD SEE UP TO ANOTHER INCH OF SNOW BY EVENING IN SOME LOCATIONS. MARINE... BRISK SOUTH WINDS WILL DEVELOP LATER THIS AFTERNOON AND TONIGHT AS A TIGHTENING SURFACE PRESSURE GRADIENT DEVELOPS BETWEEN DEPARTING HIGH PRESSURE AND AN APPROACHING TROUGH OF LOW PRESSURE. WINDS WILL BACK SOUTHWEST THEN WEST AS THE SURFACE TROUGH PASSES THROUGH WEDNESDAY. THE BRISK WINDS WILL BUILD HIGH WAVES THAT WILL SUBSIDE WEDNESDAY AFTERNOON WITH THE OFFSHORE FETCH. DID NOT CHANGE THE SMALL CRAFT ADVISORY TIMING...THOUGH IT MAY EVENTUALLY NEED TO BE EXTENDED INTO WEDNESDAY NIGHT DUE TO LINGERING BREEZY WEST WINDS. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 6 PM CST WEDNESDAY FOR LMZ645-646. SMALL CRAFT ADVISORY UNTIL 6 PM CST WEDNESDAY FOR LMZ643-644. && $$ UPDATE...DAVIS TONIGHT/WEDNESDAY AND AVIATION/MARINE...DDV WEDNESDAY NIGHT THROUGH TUESDAY...MBK
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
415 AM EST WED DEC 25 2013 .SHORT TERM...TODAY AND TONIGHT...STRONG SURFACE HIGH TO THE NORTH WILL MOVE EAST REACHING THE EAST COAST BY THIS EVENING. CURRENT IR SATELLITE IMAGERY SHOWS A LARGE AREA OF LOW CLOUDS OVER THE OFFSHORE ATLANTIC WATERS. THESE LOW CLOUDS WILL ADVECT INTO THE AREA TODAY AND TONIGHT WITH AN INVERTED TROUGH DEVELOPING OVER THE COASTAL WATERS BY TONIGHT. ISOLATED SHOWERS POSSIBLE OVER THE WATERS THIS MORNING REACHING THE COASTAL AREAS BY AS EARLY AS THIS AFTERNOON. SREF...NAM12...AND RAP MODELS ARE THE MOST AGGRESSIVE AND LOOK TOO FAST WITH THE SHOWERS. HAVE USED A BLEND WITH THE SLOWER GFS. TEMPERATURES WILL BE COOL AGAIN TODAY DUE TO INCREASING CLOUDINESS AND ONSHORE WINDS. LOWS TONIGHT WILL NOT BE AS COLD AS THIS MORNING FOR THE SAME REASONS. THU...HIGH PRES REMAINS N OF THE AREA AND LOW LEVEL NELY WINDS WILL CONTINUE TO HELP INFLUX OF LOW LEVEL MOISTURE. LLVL MOISTURE CONVERGENCE COMBINED WITH WEAK UPPER LEVEL DISTURBANCES WILL ALLOW FOR A SLIGHT TO CHANCE OF SHOWERS FOR THE AREA BUT FORCING DOES LOOK FAIRLY WEAK. WILL TWEAK INHERITED POPS DOWN A BIT TO 20-30%. CONTINUED TO LEAN TOWARD COOLER SIDE OF GUIDANCE MAX TEMPS DUE TO MOSTLY CLOUDY SKIES AND N-NELY WINDS. THU NIGHT...MODELS CONTINUE TO PREDICT A SWATH OF MOISTURE ACROSS THE AREA MAINLY ERN GULF...NE FL AND INTO THE WRN ATLC AS MID AND UPPER LEVEL FLOW BACKS IN RESPONSE TO AN APPROACHING UPPER TROUGH. SLIGHTLY BETTER FORCING ALOFT AND INCREASED MOISTURE SUGGESTS SLIGHTLY HIGHER POPS ACROSS S ZONES BUT WILL KEEP MID CHANCE POPS GOING...WITH ONLY 10-20% N PORTION. MIN RANGE FROM NEAR 40 N TO LOWER TO MID 50S S PARTS. FRI...INCREASED DIVERGENCE ALOFT AT 250 MB ATOP THE COOL N-NE FLOW...PLENTY OF MOISTURE AVAILABLE (PWAT 1.3 INCHES) AND MID LEVEL DISTURBANCES INDICATE INCREASED RAIN CHANCES...THOUGH BETTER CHANCES MAY BE LATTER PART OF THE DAY. USED A BLEND OF AVAILABLE MOS GUIDANCE DUE TO INCREASED UNCERTAINTY. BEST POPS PAINTED OVER NE FL AT 50-60% AT THIS TIME. MAX TEMPS WILL BE HELD IN CHECK BY CLOUDS AND PRECIP WITH UPPER 50S N TO MID 60S S. FRI NIGHT...SHORTWAVE TROUGHING ACROSS THE LOWER MS VALLEY AND DEEPER SW FLOW ALOFT WILL CONTINUE TO FEED MOISTURE FROM SW TO NE ACROSS THE FORECAST AREA. BEING START OF DAY 4 CHOSE TO STAY CONSERVATIVE WITH POPS AND SO CAPPED THEM AT 50% ACROSS NE FL AND 30-40% OVER SE GA BUT MOS CURRENTLY SHOWS 60-70% IN SOME LOCATIONS. MINS FCST TO ONLY DECREASE ABOUT 10 DEG FROM MAX TEMPS FROM FRI. .LONG TERM...SAT-TUE. A FAIRLY WET PATTERN SEEMS IN STORE INITIALLY WITH DEEP LAYER MOISTURE (PWAT 1.5 INCHES) ACROSS NE FL AND SE GA SAT WITH A FAIRLY STRONG SHORTWAVE TROUGH PROGRESSING ACROSS THE LOWER CONUS DURING THE WEEKEND...PUSHING OFFSHORE THE E COAST BY LATE SUN NIGHT. FOR NOW INDICATED RAIN CHANCES IN THE 40-60% RANGE SAT-SUN MORNING AND TAPERED DOWN TO 20-30% BY SUN AFTN. UNCERTAINTY IS MEDIUM WITH TIMING OF THE SLOWLY WEAKENING SHORTWAVE AS IT TRANSLATES EWD...WITH THE GFS A GOOD 12 HRS FASTER. LEFT THUNDER OUT OF FCST FOR NOW WITH VERY WEAK INSTABILITY. IT DOES LOOK LIKE SOME HEAVIER PRECIP POTENTIAL IS POSSIBLE DUE TO THE STRENGTH OF THE SHORTWAVE WAVE BUT TOO EARLY FOR SPECIFICS. BASED ON ECMWF AND GFS MOST PRECIP APPEARS TO MOVE OUT OF THE AREA BY LATE SUN NIGHT WITH A COOLER AND DRIER AIRMASS MOVING MON AND TUE. A REINFORCED SHOT OF COOL AIR MOVES IN MON NIGHT AS WELL AND SFC HIGH MOVES THRU GA AND SC ON TUE. && .AVIATION...CURRENTLY VFR CONDITIONS WITH CLEAR SKIES AND NORTH WINDS AROUND 5 KNOTS. EXPECT STRATOCUMULUS TO ADVECT INLAND AFFECTING MAINLY SSI AND CRG AROUND 12Z WITH MVFR CIGS. EXPECT MVFR CIGS TO REACH JAX AND VQQ BY 15Z AND THEN GNV AROUND MIDDAY. HAVE VCSH AT CRG AND SSI AFTER 22Z WITH THE POSSIBILITY OF IFR CIGS TONIGHT. && .MARINE...INVERTED COASTAL TROUGH PROGGED BY MODELS TO DEVELOP OVER THE WATERS BY THIS EVENING. WILL CONTINUE WITH MARGINAL ADVISORY OVER THE OFFSHORE WATERS TODAY AND CAUTION NEAR SHORE. INVERTED TROUGH WILL LIKELY CAUSE A DECREASE IN WIND SPEEDS TONIGHT AND EARLY THURSDAY BELOW ADVISORY LEVELS WITH SEAS REMAINING ELEVATED. UNFAVORABLE BOATING CONDS LOOK TO EXIST MUCH OF THE PERIOD WITH N TO NE WINDS GENERALLY IN THE 12 TO 20 KT RANGE AND SEAS AROUND 3-5 FT NEARSHORE AND 4-7 FT OFFSHORE. SMALL CRAFT ADVY CONDS LOOK POSSIBLE THU NIGHT INTO SAT AS COASTAL TROUGH REMAINS BEHIND 60 NM AND SFC HIGH PRES PUSHES SEWD TOWARD THE SE COAST PINCHING THE LOCAL PRES GRADIENT. A QUICK INCREASE IN N-NW FLOW IS POSSIBLE SUN AS WELL WITH SFC LOW PRES DEVELOPING NEAR OR E OF THE GULF STREAM AS AN UPPER DISTURBANCE MOVES THROUGH THE AREA...BUT NOT ENOUGH CONFIDENCE TO GO HIGH ON THE WINDS AT THIS POINT. RIP CURRENTS: MODERATE RISK WILL CONTINUE THROUGH THE WEEK DUE TO ELEVATED ONSHORE WINDS AND SEAS. && .PRELIMINARY POINT TEMPS/POPS... AMG 55 41 54 38 / 0 20 20 10 SSI 58 48 56 45 / 20 30 30 30 JAX 59 45 57 45 / 10 30 30 40 SGJ 61 53 61 52 / 10 30 40 50 GNV 64 48 61 46 / 0 20 40 50 OCF 66 49 63 50 / 0 20 40 50 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...SMALL CRAFT ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR ALTAMAHA SOUND GA TO FERNANDINA BEACH FL 20 NM TO 60 NM OFFSHORE- FERNANDINA BEACH TO ST AUGUSTINE FL 20 NM TO 60 NM OFFSHORE- ST AUGUSTINE TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE. && $$ ZIBURA/SHASHY/
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
312 AM EST WED DEC 25 2013 ...CHILLY CHRISTMAS MORNING FOR WEST CENTRAL AND SOUTHWEST FLORIDA... .SHORT TERM /TODAY-FRIDAY/... CHRISTMAS MORNING BEGINS WITH A CHILL IN THE AIR...AS MUCH OF WEST CENTRAL AND SOUTHWEST FLORIDA IS IN THE 40S AND 50S. PORTIONS OF LEVY COUNTY ARE IN THE UPPER 30S TO LOWER 40S...STARTING TO BELIEVE THAT SOME HIGH CLOUDS COULD PREVENT THE EFFICIENT RADIATIONAL COOLING PREVIOUSLY EXPECTED. THE FREEZE WARNING FOR LEVY REMAINS POSTED...AND WILL BE EXAMINED AGAIN IN THE COMING HOURS AS WE NEAR SUNRISE. THE STALLED FRONT THAT PASSED THROUGH THE AREA YESTERDAY WILL BEGIN TO SEEP NORTHWARD...PROVIDING A RETURN OF MOISTURE ALL THE WAY INTO NORTH FLORIDA BY THE END OF CHRISTMAS DAY. PORTIONS OF NORTH FLORIDA COULD SEE INCREASING CLOUD COVERAGE...AS ADVERTISED IN SOME GUIDANCE INCLUDING THE SREF...WHICH COULD KEEP TEMPERATURES ACROSS THE NATURE COAST IN THE 60S OR LOWER 70S. OTHERWISE...THE AREA TO THE SOUTH OF THAT CLOUD COVER SHOULD BE ABLE TO REACH INTO THE 70S BEFORE CLOUDS ASSOCIATED WITH THE RETURN FRONTAL MOISTURE MOVE IN THIS AFTERNOON. ONE BENEFIT TO THE CLOUD COVER WILL BE THAT TEMPERATURES ON CHRISTMAS NIGHT WILL BE A TAD WARMER. AREAS OF THE NATURE COAST WILL BE IN THE UPPER 40S TO LOWER 50S...WITH AREAS AROUND TAMPA BAY IN THE MID 50S TO LOWER 60S IN SW FLORIDA. THE ADDITIONAL MOISTURE WILL ALSO CREATE INCREASING RAIN SHOWER CHANCES...WHICH TREND INTO A WETTER END TO THE WEEK. MODEL GUIDANCE IS MIXED AS TO RAIN TIMING...WITH THE 00Z NAM MET MOS KICKING IN THE RAIN CHANCES MUCH SOONER THAN THE 00Z GFS MAV MOS GUIDANCE. TOOK A MIDDLE OF THE ROAD APPROACH TO MUCH OF THE FORECAST...TRENDING WET INTO THE WEEKEND SIMILAR TO PREVIOUS FORECASTS. A MID-LEVEL TROUGH SWINGING THROUGH THE EASTERN UNITED STATES ON THURSDAY SHOULD PROVIDE SUPPORT FOR RAIN SHOWERS THURSDAY EVENING THROUGH THURSDAY NIGHT. COMBINE THAT WITH THE RETREATING FRONT COMING IN FROM THE SOUTH AND RAIN SHOWER CHANCES SHOULD BE MORE SOLID THAN THEY WERE WITH THIS LAST FRONT. THE CLOUDY AND WET PATTERN WILL BE REINFORCED ON FRIDAY THANKS TO A HEALTHY STREAM OF GULF MOISTURE ALONG WITH THE REMNANT FRONTAL BOUNDARY. TEMPERATURES COULD BE A BIT TRICKY DEPENDING ON HOW MUCH CLOUD COVER IS OVER A LOCATION. THE LOCATION OF THE BOUNDARY WILL PLAY A LARGER ROLE ON FRIDAY...WITH GUIDANCE BRINGING A CONSENSUS WITH THE PEAK CLOUD COVER SITTING NORTH OF TAMPA BAY. IF THIS CHANGES...SO DRASTICALLY COULD TEMPERATURES FOR FRIDAY. WE WISH YOU A MERRY CHRISTMAS AND HOPE THAT YOU ENJOY THE DAY! .LONG TERM /FRI NIGHT-WEDNESDAY/... AN U/L RIDGE OVER THE FOUR CORNERS AREA WILL WEAKEN SATURDAY WHILE A STRONG U/L DISTURBANCE PUSHES SOUTH DOWN THE CALIFORNIA COAST. ANOTHER U/L DISTURBANCE WILL BE OVER THE LOWER MISSISSIPPI VALLEY AND WILL MOVE EAST ALONG THE NORTHERN GULF OF MEXICO. PREVIOUS RUNS HAD THE DISTURBANCE ALONG THE CALIFORNIA COAST CUTTING OFF AND FORMING A REX BLOCK OFF THE CALIFORNIA COAST. CURRENT GUIDANCE NOW TRENDING TOWARD DISTURBANCE REMAINING IN SOUTHERN STREAM FLOW AND DIGGING OVER THE SOUTHWEST U.S. AND BAJA CALIFORNIA SUNDAY...WITH THE LEAD SOUTHERN STREAM DISTURBANCE OVER THE LOWER MISSISSIPPI VALLEY MOVING EAST ACROSS THE SOUTHEAST U.S. AND FLORIDA SATURDAY NIGHT AND SUNDAY. L/W TROUGH ASSOCIATED WITH MAIN NORTHERN STREAM FLOW WILL BE LOCATED FROM HUDSON BAY SOUTH THROUGH THE OHIO RIVER VALLEY SUNDAY NIGHT AND MONDAY...WITH QUASI ZONAL FLOW ACROSS THE GULF OF MEXICO AND FLORIDA IN THE SOUTHERN STREAM. NORTHERN STREAM TROUGH WILL ROTATE EAST OFF THE EASTERN SEABOARD MONDAY NIGHT AND TUESDAY WITH ADDITIONAL WEAKER IMPULSES DROPPING DOWN THE BACKSIDE OF THE TROUGH...WITH THE DISTURBANCE OVER THE SOUTHWEST U.S. SLOWLY MOVING ACROSS TEXAS...WEAKENING AND OPENING UP WHILE BEING ABSORBED IN THE NORTHERN STREAM FLOW. AT THE SURFACE...STATIONARY FRONTAL BOUNDARY WILL BE LOCATED ACROSS THE CENTRAL FLORIDA PENINSULA FRIDAY NIGHT THROUGH EARLY SUNDAY. AN INCREASING CHANCE OF SHOWERS ACROSS THE FORECAST AREA FRIDAY NIGHT AND SATURDAY WHICH WILL BE ENHANCED BY THE APPROACHING U/L DISTURBANCE. WILL TREND POPS BELOW GUIDANCE AT THIS POINT AS GUIDANCE HAS BEEN INCONSISTENT WITH AREAL COVERAGE OF RAIN. WEAK SURFACE LOW MAY DEVELOP ALONG THE FRONTAL BOUNDARY WHICH WOULD ENHANCE LOW LEVEL CONVERGENCE. AS THE U/L DISTURBANCE MOVES EAST OF THE AREA ON SUNDAY...IT WILL PUSH THE FRONTAL BOUNDARY SOUTH OF THE FLORIDA PENINSULA. SURFACE HIGH PRESSURE WILL BUILD OVER WEST CENTRAL AND SOUTHWEST FLORIDA SUNDAY AND MONDAY IN THE WAKE OF THE DISTURBANCE WITH SLIGHTLY COOLER DRIER AIR ADVECTING OVER THE AREA. A WEAK SECONDARY COLD FRONT WILL PUSH ACROSS THE FLORIDA PENINSULA MONDAY NIGHT REINFORCING THE COOLER DRIER AIRMASS. TEMPERATURES WILL BEGIN ABOVE CLIMATIC NORMALS SATURDAY AND SUNDAY BUT WILL COOL TO NEAR CLIMATIC NORMALS MONDAY THROUGH WEDNESDAY. && .AVIATION... VFR CONDITIONS EXPECTED FOR THE NEXT 24 HOURS. VFR CIGS 040-050 SPREADING OVER SOUTHWEST FLORIDA VCNTY RSW/FMY/PGD EARLY THIS MORNING...AND GRADUALLY LIFTING NORTHWEST TOWARD THE REMAINING TERMINALS BY THIS AFTERNOON. && .MARINE... HAVE EXTENDED THE SMALL CRAFT ADVISORY FOR THE SOUTHERN OUTER WATERS A FEW HOURS...AND HAVE ALLOWED THE OTHERS TO EXPIRE. ISSUED SCEC FOR TAMPA BAY THANKS TO GUSTY WINDS REPORTED IN AND AROUND THE BAY...MAINLY IN PINELLAS COUNTY THIS MORNING. WILL CONTINUE TO MONITOR AND UPDATE PRODUCTS AS NECESSARY. && .FIRE WEATHER... MOISTURE RETURN TODAY SHOULD MITIGATE ANY FIRE WEATHER CONCERNS THROUGH THE END OF THE WEEK. && .PRELIMINARY POINT TEMPS/POPS... TPA 73 59 75 59 / 0 30 30 40 FMY 78 62 82 63 / 10 20 30 30 GIF 73 56 76 57 / 10 20 30 30 SRQ 75 59 77 61 / 0 30 30 40 BKV 72 53 74 58 / 0 10 30 40 SPG 71 60 73 62 / 0 30 30 40 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...FREEZE WARNING UNTIL 8 AM EST THIS MORNING FOR COASTAL LEVY-INLAND LEVY. GULF WATERS...SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR BONITA BEACH TO ENGLEWOOD OUT 20 TO 60 NM-ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60 NM. && $$ SHORT TERM/MARINE/FIRE WEATHER...02/GARCIA LONG TERM/AVIATION...13/OGLESBY
  [top] Area Forecast Discussion National Weather Service Tallahassee FL 246 AM EST Wed Dec 25 2013 .Near Term [Today]... The Christmas Day temperature forecast in our area is a bit tricky, complicated by the arrival of a couple different cloud layers. The first cloud layer is a low stratus deck that has evolved in the last 6-10 hours just offshore coastal SC, GA, and NE FL. Model guidance is in good agreement to gradually veer the flow in the 925-850mb layer to an E-ESE direction by the mid-morning hours, which should cause the stratus deck and greater low-level moisture to spread inland from the Atlantic, underneath a pronounced inversion. The second cloud layer will be a band of increasing cirrostratus that should gradually lower to around 15-20kft during the day per model forecast soundings. The consensus is that 500-300mb RH will quickly spike to around 80% between 18-21z, which should create a veil of high cloud cover over the area this afternoon. The question, of course, is whether or not the cloud cover arrives in sufficient time to significantly limit daytime heating. Confidence would be highest in this occurring (with the stratus deck advancing from the east) over SC GA, particularly east of a TVI-ABY line. The latest runs of the RAP hold temperatures in the mid-upper 40s all day in our Georgia zones consistent with the idea of an expanding stratus deck. We did not lower the high temperature forecast quite that aggressively, but more raw model guidance was blended in with the usually favored MOS over land to produce highs mostly in the lower 50s in the northern half of the area. It should be noted that there is a considerable range of possibilities for "Day 1" of the forecast. An early arrival of the stratus layer could realistically produce highs in the 40s in SW GA. Cloud cover that takes longer to materialize could yield mid-upper 50s in those same areas. For now we`ve taken a compromise approach and our forecast generally lies near or just below the model average. .Short Term [Tonight Through Friday]... Our forecast area will come under the influence of moistening southwest flow aloft as the polar jet stream remains well north of our region. A series of short wave troughs will translate quickly eastward across the northern CONUS, leaving our area to get "fringe" effects from these systems as they pass quickly to our north. Additionally there will be a slow-moving, positively tilted trough over the western Gulf of Mexico. The result of this pattern is a rather tricky forecast, as forecasting the timing and interaction of these systems is often difficult. The first system will affect our region tonight. Although there will be an increase in moisture and Q-G forcing, there will likely be some residual dry layers (as indicated in the forecast soundings), so our QPF and PoP is low. Moisture and Q-G forcing will gradually increase again Thursday night and Friday, with a corresponding increase in PoP. Rain chances will generally be confined to the region along and south of a line from Valdosta to Cape San Blas, as north of this line it will probably be too dry for rain. Even where rain is possible, we expect it to be too stable and the forcing too weak for thunderstorms. Lows will range from the mid to upper 30s in our northwest zones to mid 40s in our FL zones. Highs will be in the upper 50s to lower 60s, unless there are more clouds and rain than currently forecast. .Long Term [Friday Night Through Wednesday]... Some fairly significant changes to the new long term fcst as the latest run of the ECMWF shows a more potent upper level shortwave digging down into TX early in the weekend. It now appears that this system will have just enough punch to potentially give us another wet weekend with increasing rain chances for Sat. and Sun. Even the GFS is starting to trend in this direction, so confidence for higher PoPs is increasing for the beginning of the extended fcst. Thereafter, however, it appears that the upper level pattern will become very progressive, with a couple of fast moving shortwave trofs moving through the region during the early to middle portion of next week. This should keep conditions on the fair, cool, and dry side for the remainder of the period, as we usher in the New Year of 2014 on next Wed. && .Aviation... [Through 06Z Thursday] Model guidance is in very good agreement that a stratus deck will expand inland over SE GA and NE FL early this morning, and eventually into parts of the FL Big Bend and SW GA by midday or early afternoon. This would be most likely to impact VLD and ABY, with TLH and DHN peripherally affected. Several short term ensembles have the probability of MVFR CIGS at ABY and VLD climbing to around 90% by 18z, with lesser values of 50-60% at TLH and DHN. Model forecast soundings show the ceiling could be as low as 2000 feet. For now, we included a 3000ft - marginal MVFR - ceiling at the aforementioned TAF sites, gradually spreading ESE-WNW today. && .Marine... Winds and seas were below advisory levels this early morning. However, moderate northeast winds are likely to continue for the next several days as a series of high pressure systems develop to our north. && .Fire Weather... Humidity will moderate from the low levels yesterday for the rest of the week. Red flag conditions are not expected. && .Hydrology... Increased flows from rainfall over the weekend continue to progress through the river system. There is still a possibility that the Choctawhatchee River at Caryville could reach minor flood stage on 12/27, however measured flows within the Pea and upper Choctawhatchee Rivers may not be sufficient enough for the lower Choctawhatchee to flood. Releases from Woodruff Dam continue and have been increased to 45 kcs this evening and may move to near 50 kcfs on Wednesday. As a result, Blountstown will reach flood stage on 12/25 and should remain in the minor flood category for some time. Elsewhere in the region, the Shoal River in Walton County has crested and will continue to sharply fall. Modest rises on the Flint will continue, but should stay at or just below action levels through the weekend. East of the Flint River drainage area, rainfall was insufficient to result in any significant rises in the Withlacoochee or Suwannee River systems. && .Preliminary Point Temps/PoPs... Tallahassee 57 45 60 42 61 / 0 20 20 20 20 Panama City 60 45 60 46 62 / 0 10 10 10 10 Dothan 52 38 57 38 61 / 0 10 10 10 0 Albany 51 38 57 37 59 / 0 20 20 10 10 Valdosta 55 43 58 41 60 / 0 20 20 20 20 Cross City 66 47 66 47 62 / 0 10 20 40 40 Apalachicola 60 47 61 49 62 / 0 20 20 20 20 && .TAE Watches/Warnings/Advisories... FL...Freeze Warning until 9 AM EST /8 AM CST/ this morning for Calhoun-Central Walton-Coastal Bay-Coastal Dixie-Coastal Franklin-Coastal Gulf-Coastal Jefferson-Coastal Taylor- Coastal Wakulla-Gadsden-Holmes-Inland Bay-Inland Dixie- Inland Franklin-Inland Gulf-Inland Jefferson-Inland Taylor- Inland Wakulla-Inland Walton-Jackson-Lafayette-Leon-Liberty- Madison-South Walton-Washington. GA...Freeze Warning until 9 AM EST this morning for Baker-Ben Hill- Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur-Dougherty- Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller-Mitchell- Quitman-Randolph-Seminole-Terrell-Thomas-Tift-Turner-Worth. AL...Freeze Warning until 8 AM CST this morning for Coffee-Dale- Geneva-Henry-Houston. GM...None. && $$ Near Term...Lamers Short Term...Fournier Long Term...Gould Aviation...Lamers Marine...Fournier Fire Weather...Lamers Hydrology...Godsey
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1201 AM CST WED DEC 25 2013 .DISCUSSION... 810 PM CST MADE SOME ADJUSTMENTS TO HOURLY TEMPERATURES TO ACCOUNT FOR A QUICK FALL THIS EVENING...BUT WITH CLOUD COVER THICKENING AND LOWERING AND WARM AIR ADVECTION STRENGTHENING WOULD ANTICIPATE STEADY OR RISING TEMPS THE REMAINDER OF THE NIGHT. FIRST BATCH OF SNOW OVER EASTERN IOWA LOOKS TO BE TAKING AIM ON MOSTLY WISCONSIN AS VERY DRY AIR (RH AROUND 10% AT 850MB ON 00Z DVN SOUNDING) IS RESULTING IN A BIG VIRGA STORM OVER NORTHERN ILLINOIS AT THIS TIME. GUIDANCE STILL INDICATES THAT INCREASING ASCENT AND CONTINUED MOISTENING FROM TOP DOWN WILL LIKELY RESULT IN SATURATION AND SNOW DEVELOPING LATER THIS EVENING AND PARTICULARLY AFTER MIDNIGHT. LATEST SUITE OF GUIDANCE HAS BEEN INCREASINGLY PESSIMISTIC WITH RESPECT TO QPF AMOUNTS OVER OUR CWA LATER TONIGHT INTO XMAS MORNING. WOULD NOT TAKE MUCH TO SQUEEZE OUT A TENTH OF AN INCH OF SNOWFALL SO ONLY GOING TO SCALE BACK POPS SLIGHTLY OVER CENTRAL AND SOUTHERN PORTIONS OF THE CWA WHILE MAINTAINING CATEGORICAL. REGARDING SNOWFALL TOTALS...LATEST GUIDANCE WOULD SUGGEST THAT EVEN AN INCH WOULD BE UNATTAINABLE WITH THIS SYSTEM EXCEPT FOR FAR NORTHERN COUNTIES. NOT TERRIBLY KEEN ON MAKING BIG CHANGES ON THIS SHIFT...SO GOING TO JUST GENTLY SCALE BACK AMOUNTS A BIT RATHER THAN GO WITH WHAT IS LOOKING TO BE THE MORE LIKELY SCENARIO WHICH IS MOST AREAS GETTING LITTLE MORE THAN A DUSTING THROUGH CHRISTMAS MORNING. SECOND SHORTWAVE PIVOTING AROUND THE POLAR VORTEX STILL LOOKS ON TARGET TO BRING ANOTHER CHANCE OF SNOW SHOWERS LATER TOMORROW AFTERNOON INTO TOMORROW EVENING...AGAIN ESPECIALLY NORTHERN CWA. WILL LET THE NIGHT CREW HANDLE ANY GRID ADJUSTMENTS WITH THAT SYSTEM. IZZI //PREV DISCUSSION... 225 PM CST MAIN FORECAST CONCERNS WILL BE HONING IN ON A PAIR OF DISTURBANCES BRINGING ACCUMULATING SNOW TONIGHT AND AGAIN DURING THE EVENING TOMORROW...AS WELL AS TEMPERATURE TRENDS WITH NON-DIURNAL TEMPS TONIGHT AND BITTER COLD RETURNING EARLY NEXT WEEK. TODAY AND TONIGHT... PAIR OF UPPER LEVEL DISTURBANCES EVIDENT ON WATER VAPOR IMAGERY THIS AFTERNOON...THE FIRST TRANSLATING EAST ACROSS NEBRASKA...WHILE A SECOND WAVE IS DIGGING ACROSS THE CANADIAN PRAIRIES. THE SOUTHERN WAVE IS FORECAST TO LIFT ACROSS NRN IL/SRN WI OVERNIGHT. ISENTROPIC ASCENT INCREASES AHEAD OF THE WAVE LATE THIS EVENING...WITH TOP DOWN SATURATION GRADUALLY EATING AWAY AT THE VERY DRY AIR MASS CURRENTLY IN PLACE. MOST MODELS INDICATE THAT PRECIP WILL BEGIN JUST BEFORE MIDNIGHT OVER NORTH CENTRAL ILLINOIS AND INITIALLY WILL BE MAINLY CONFINED TO THE TIER OR TWO OF COUNTIES NEAR THE STATE LINE WITH DRY AIR WINNING OUT OVER AREAS FARTHER SOUTH. COLD TEMPERATURES WITH A FAIRLY DEEP ISOTHERMAL LAYER THAT EXTEND FROM NEAR THE SURFACE TO ABOUT 6KFT AND COINCIDES NEAR THE BASE OF THE DENDRITIC GROWTH ZONE WILL HELP LEAD TO FLUFFIER THAN AVERAGE SNOW RATIOS...17-20:1 INITIALLY PER COBB OUTPUT. BETTER FORCING ASSOCIATED WITH THE UPPER WAVE WILL BE RIGHT ON THE HEALS OF THIS FIRST WARM ADVECTION BURST OF SNOW AND WILL LEAD TO SNOW SPREADING SOUTHEAST ACROSS THE REMAINDER OF THE CWA...INCLUDING THE CHICAGO METRO AREA BY AROUND 3AM CST. DGZ NOT NEARLY AS DEEP OVER REMAINDER OF CWA WITH SLIGHTLY WARMER TEMPS IN THE LOW/MID LEVELS AND A 2-3KFT DEEP DGZ NEAR THE TOP OF THE SATURATED LAYER BUT COINCIDING WITH THE BETTER LIFT. THIS WILL RESULT IN STILL DRY BUT CLOSER TO AVERAGE RATIOS OF 14-16:1. WITH A BLEND OF NAM/GFS TIMING/QPF THIS EVENING...CONTINUE TO CALL FOR 1-3 INCHES OF SNOW NORTH OF THE I-88 CORRIDOR...1 TO 2 INCHES BETWEEN I-88 AND A PONTIAC TO VALPARAISO LINE...AND UP TO AN INCH SOUTH OF THAT LINE. IN ADDITION TO ACCUMULATING SNOWFALL...PRESSURE GRADIENT WILL TIGHTEN BETWEEN A STRONG DEPARTING HIGH CURRENTLY OVERHEAD AND THE APPROACHING FRONTAL TROUGH. THIS WILL RESULT IN BREEZY CONDITIONS DEVELOPING OVERNIGHT WITH GUSTS INTO THE 20 TO 25 MPH RANGE. GIVEN THE DRY NATURE OF THE SNOW...THIS WILL LIKELY CONTINUE TO BLOW SNOW AROUND AFTER IT FALLS TO THE SURFACE. THE INCREASING SOUTHERLY FLOW WILL ALSO LEAD TO WARMING TEMPERATURES THROUGH THE OVERNIGHT HOURS WITH LOWS HAPPENING THIS EVENING. BY DAYBREAK TOMORROW...EXPECT TEMPERATURES TO WARM INTO THE HIGH TEENS TO LOW 20S. WEDNESDAY THROUGH FRIDAY... AFOREMENTIONED NORTHERN WAVE WILL CONTINUE TO DIG INTO THE MIDWEST...CARVING OUT A TROUGH THAT WILL SHIFT EAST ACROSS THE AREA LATE WEDNESDAY EVENING. MOISTURE WITH THIS SECOND WAVE IS MORE SHALLOW...AND WILL BE LOOKING AT CLOSER TO AVERAGE SNOW RATIOS. QUICK HITTING SYSTEM MAY PRODUCE UP TO AN ADDITIONAL INCH NORTH OF THE I-88 CORRIDOR WITH LITTLE IF ANY SNOW SOUTH. TEMPERATURES WEDNESDAY NIGHT A BIT TRICKY...WITH SOME GUIDANCE POINTING AT MUCH COOLER TEMPS THAN FORECAST...IN FACT SUB ZERO WEST OF THE FOX RIVER VALLEY. HOWEVER...YET ANOTHER VORT LOBE WILL PIVOT ACROSS THE AREA...AND WHILE DO NOT EXPECT ANY APPRECIABLE PRECIP WITH THIS WAVE...IT SHOULD AT LEAST HOLD ONTO CLOUD COVER OVERNIGHT. WITH THE RIDGE AXIS CENTERED OVER IOWA...DOES NOT APPEAR TO FAVOR A STRONG RADIATIONAL COOLING SETUP AND WILL DISMISS THE COLDEST GUIDANCE. RIDGE AXIS WILL ARRIVE OVERHEAD MIDDAY THURSDAY AND SHOULD KEEP CONDITIONS DRY MOST OF THURSDAY AND FRIDAY. THOUGH AS THE SURFACE RIDGE BREAKS DOWN LATER THURSDAY AND FRIDAY...WITH THE AREA UNDER NORTHWEST FLOW WILL HAVE TO KEEP AN EYE ON THE POTENTIAL FOR A EVEN A WEAK UPPER LEVEL DISTURBANCE TO SQUEEZE OUT SOME LIGHT SNOW...AS SUGGESTED BY THE NAM. WILL KEEP "SILENT" 10-14 POPS IN THE MEANTIME. SATURDAY THROUGH TUESDAY... MODELS HAVE BEEN ADVERTISING A RELATIVELY STRONG CLIPPER SYSTEM TO IMPACT PRIMARILY THE NORTHERN LAKES REGION OVER THE WEEKEND WITH SMALL CHANCES FOR SNOW INTO NORTHERN ILLINOIS WITH A STRONG COLD FRONT SWEEPING ACROSS THE AREA. AHEAD OF THE FRONT ON SATURDAY... 7-8C H85 THERMAL RIDGE WILL ADVECT OVERHEAD. EVEN WITH SOME SNOW ON THE GROUND...LOCAL UPPER AIR CLIMATOLOGY SUGGESTS THAT MOST AREAS SHOULD BE ABLE TO GET WELL INTO THE 30S...WITH LOW 40S EVEN A POSSIBILITY...AN IDEA SUPPORTED BY A CONSENSUS MODEL BLEND. A STRONG COLD FRONT WILL SWEEP ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY WITH H85 TEMPS PLUMMETING TO -17 TO -18C BY SUNDAY NIGHT. DEPENDING ON THE EXACT TIMING THE OF THE FRONT...THIS COULD LEAD TO EARLY MORNING LOWS SUNDAY WITH TEMPS FALLING THROUGH THE DAY AND NIGHT...BOTTOMING OUT IN THE LOW SINGLE DIGITS OR EVEN BELOW ZERO ONCE AGAIN...WITH THE COLD AIR MASS LINGERING INTO THE DAY TUESDAY. BACK UNDER NORTHWEST FLOW ALOFT...THERE WILL BE PERIODIC CHANCES FOR LIGHT SNOW EARLY NEXT WEEK. DEUBELBEISS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * LIGHT SNOW POSSIBLY REDEVELOPS LATE TONIGHT ARND 9Z AND CONTINUES THRU 12Z. * VFR CIGS THEN DIMINISH TO LOW END MVFR WITH LGT SNOW ARRIVAL...THEN BORDERLINE IFR CIGS ARND DAYBREAK THRU MIDDAY. * MVFR TO VFR CIGS BY LATE WED AFTN. * ANOTHER PERIOD OF LGT SNOW AFT 23Z THRU 03Z THUR. BEACHLER //DISCUSSION...UPDATED 06Z... CLIPPER SYSTEM CONTINUES TO SLIDE EAST ACROSS THE REGION. REGIONAL RADAR SHOWS A BREAK IN THE LIGHT SNOW ACROSS NORTHERN IL/NORTHWEST IN...HOWEVER A SECOND WAVE APPEARS TO BE DEVELOPING AND MAY REDEVELOP THE LIGHT SNOW ACROSS THE AREA ARND 9-10Z AND CONTINUE THRU 12Z. CIGS HAVE HELD UP AT VFR CONDS...AND WITH LGT SNOW REDEVELOPING CIGS SHUD COME DOWN TO LOW END MVFR CONDS. GUIDANCE THEN CONTINUES TO SUGGEST CIGS WILL HOLD DOWN AT MVFR TO BORDERLINE IFR CONDS THRU MIDDAY. AS WINDS REMAIN SOUTHERLY WITH OCCASIONAL GUSTS TO 15-19KT...SOME DRY AIR EVENTUALLY WORKS BACK INTO THE AREA MIDDAY AND ALLOWS CIGS TO LIFT TO HIGH END MVFR CONDS. THEN YET ANOTHER CLIPPER IS POISED TO ARRIVE AFT 22Z...WITH LIGHT SNOW DEVELOPING ARND 00-03Z THUR. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM CONFIDENCE ON REDEVELOPING LGT SNOW AFT 9Z THRU 12Z. * HIGH CONFIDENCE IN CIGS THRU 12Z...MEDIUM CONFIDENCE IN CIGS AFT 12Z THRU MIDDAY. * HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS. * LOW/MEDIUM CONFIDENCE IN LGT SNOW DEVELOPING AFT 22Z. BEACHLER //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... THU THROUGH MON...VFR. SLIGHT CHANCE -SN ON SUN AS WELL AS MON NIGHT. && .MARINE... 215 PM CST MAIN CONCERNS FOR THE LAKE ARE GALES DEVELOPING THIS EVENING AND CONTINUE THROUGH WEDNESDAY MORNING. HAZARDOUS WAVES/WINDS WILL ALSO DEVELOP FOR THE NEARSHORE WATERS AND MAY ALSO SEE OCCASIONAL GALE FORCE GUSTS IN THE NEARSHORE WATERS OVERNIGHT THRU DAYBREAK WEDNESDAY. SFC RIDGE OVER THE OHIO VALLEY WILL CONTINUE TO DRIFT EAST TONIGHT...WITH A TIGHTENING GRADIENT ALONG THE WESTERN EDGE. THIS TIGHT GRADIENT WILL SLIDE OVER THE LAKE TONIGHT...PRODUCING SOUTH/SOUTHWEST GALES BETWEEN 35-40KT OVERNIGHT. THE GRADIENT CONTINUES TO SLIDE EAST WITH THE ARRIVAL OF A CLIPPER LOW PRESSURE. THIS CLIPPER WILL ALLOW THE WINDS TO BECOME WESTERLY...AND SHOULD SEE GALES COME TO AN END BY MID-MORNING WED. HOWEVER THE GRADIENT WILL REMAIN RELATIVELY STRONG AND PRODUCE WINDS TO 30KT THRU MIDDAY WED BEFORE DIMINISHING TO 15 TO 25 KT BY WED NIGHT. THE NEXT WEATHER SYSTEM TO BRING A STRONG GRADIENT TO THE LAKE WILL ARRIVE SAT...AND LIKELY PRODUCE WINDS TO 30KT. IT IS POSSIBLE A FEW GUSTS TO GALE FORCE MAY OCCUR SAT. THEN ANOTHER STRONG RIDGE OF HIGH PRESSURE WILL SLIDE SOUTH FROM CENTRAL CANADA FOR THE SECOND HALF OF THE WEEKEND AND MAY BRING A TIGHT GRADIENT TO THE LAKE. BEACHLER && .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 UNTIL 9 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 10 PM WEDNESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 1153 PM CST Tue Dec 24 2013 .DISCUSSION... ISSUED 859 PM CST Tue Dec 24 2013 Plan to update forecast to reduce snow chances tonight and Christmas morning. WAA/isentropic lift ahead of main clipper wave is rapidly shifting east of the area. This forcing has done little more than develop a deck of mid clouds locally. Forcing with the upper wave itself is expected to arrive overnight into the morning hours. There is currently very little snow occurring with the wave right now, at least with the portion of the wave likely to impact central Illinois, and the latest HRRR and 00Z NAM have trended drier. Low temperatures for the night have likely already been attained, with good southerly flow helping temperatures to be steady or slowly rise through the night. This portion and the remainder of the short term forecast is in good shape and only minor tweaks are needed for the latest hourly trends. Bak && .AVIATION... ISSUED 1153 PM CST Tue Dec 24 2013 Cigs continue to thicken/lower across the central Illinois terminals this evening as a clipper system begins to move across the area. Expect conditions to degrade to MVFR by morning, possibly aided by some light snow from the clipper. At this point, KPIA and KBMI appear most likely to see some snow. While cloud conditions are not entirely clear as the clipper departs later on Christmas Day, plan to keep most terminals MVFR through the end of the 06Z TAF valid time. Bak && .PREV DISCUSSION... ISSUED 250 PM CST Tue Dec 24 2013 Very few changes needed to the forecast as the models remain fairly consistent and in pretty good agreement throughout much of the forecast period. Periodic shots of cold air with no major storms, followed by brief warm-ups will be the main weather trend for the upcoming week. SHORT TERM...Tonight through Thursday High pressure, which brought sub-zero readings to parts of central Illinois this morning, was centered in southwest IN early this afternoon. A southerly wind flow has already developed in Illinois, and this will continue to increase through the evening and overnight. The result will be slowly rising temperatures through the night and into Christmas morning. A clipper system in the northern Plains and its associated weak surface low in north central Nebraska will shift to the ESE tonight, spreading light snow into west central IL mainly after midnight. The axis of the light snow will shift east of the I-55 corridor around daybreak, with lingering flurries to the west. By late morning the snow should come to an end in much of east central Illinois, with some lingering flurries from PIA-DEC-MTO- Robinson. Most areas can expect around 0.5" or less of snow, except in locations from Canton to just north of Bloomington where 1.0 to 1.5 inches are likely. The snow should be rather fluffy and will blow around quite a bit with a southwest wind of 10 to 15 mph. Partial clearing is then expected in the wake of the clipper system with temperatures in the lower to middle 30s. Another clipper system will follow on the heels of the first one later on Christmas Day, but the measurable snow should stay well north of central IL. This system will bring central Illinois a glancing blow of colder air, so highs on Thursday will be a bit cooler along and north of I-74. The rest of central and SE IL can expect highs Thursday to be very similar to Wednesday`s. LONG TERM...Friday through Tuesday Overall, the medium and long range models are in pretty good agreement with the mean upper level flow from the weekend into early next week. By Friday, the upper level trough axis in the eastern U.S. will breakdown and become flatter/more westerly. This will allow temperatures to warm slightly Friday, with a nice warm- up well into the 40s expected Saturday. Locations north of I-74, however, may have some lingering snow which could keep temperatures down in the upper 30s. Both the GFS and European agree that the main longwave trough will re-establish itself in the eastern U.S. by early next week. However, they arrive at the solution differently - particularly Sunday into Monday. The GFS is weaker with the trough early on, and redevelops the longwave gradually. The European is stronger and sharper with the shortwaves that carve out the new trough, which results in a solution of light snow Sunday in the upper Midwest and northern IL. Low level moisture will be quite low, and due to the lack of persistence in the European model with this scenario will hold of on mentionable PoPs for now, and keep the forecast in the slight chance category. Both models do agree, however, that another shot of very cold air is in store for the Midwest by late Sunday and lasting into New Year`s Eve with lows in the single digits to lower teens, and highs in the teens to lower 20s. Miller && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1201 AM EST WED DEC 25 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 438 PM EST TUE DEC 24 2013 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOWS SHRTWV RDG AXIS MOVING INTO THE WRN LKS BTWN DEPARTING TROF IN THE SE GRT LKS RESPONSIBLE FOR LES THE PAST FEW DAYS AND A PAIR OF SHRTWVS DIGGING SEWD THRU SCENTRAL CANADA/THE NRN ROCKIES E OF MEAN RDG NEAR THE W COAST. WITH SFC HI PRES BLDG ACRS THE AREA...LINGERING LES NEAR LK SUP HAS DIMINISHED AND PUSHED INTO THE OPEN WATERS AS THE FLOW IS SHIFTING TO THE SSW IN ADVANCE OF THE SFC LO PRES TROF IN THE NRN PLAINS ASSOCIATED WITH THE TWO CLIPPER SHRTWVS. THE 12Z INL/MPX RAOBS SHOWED A VERY DRY AIRMASS WITH PWATS UNDER 0.10 INCH...SO SKIES ARE TURNING MOSUNNY AT MOST PLACES AS THE SSW FLOW SHIFTS LINGERING LO CLDS BACK OUT OVER LK SUP. MID CLDS IN ADVANCE OF APRCHG CLIPPER SHRTWVS/SFC TROF ARE PUSHING EWD THRU MN...WITH SN FALLING OVER NW MN AND THE ERN DAKOTAS. ALTHOUGH THIS SN HAS BEEN MDT AT SOME PLACES UNDER THE SHARPER H85-5 QVECTOR CVNGC...THE COVERAGE APPEARS TO BE LIMITED BY ABSENCE OF SGNFT MSTR INFLOW. MAIN FCST CONCERNS IN THE SHORT TERM ARE EXPECTED POPS/SN AMOUNTS LATE TNGT AND XMAS MRNG ASSOCIATED WITH UPSTREAM CLIPPER SHRTWVS AND GOING WINTER STORM WATCH OVER THE ERN CWA/NEED FOR ANY NEW HEADLINES. TNGT INTO XMAS DAY...UPR TROF TO THE NW IS FCST TO SHIFT TO THE SE AND STRETCH FM NW ONTARIO THRU MN AND INTO THE CENTRAL PLAINS BY 12Z WED. MODELS SHOW PCPN IN ADVANCE OF THIS TROF ARRIVING OVER THE WRN CWA LATE THIS EVNG AND PUSHING TO THE E...WITH A 6-9 PERIOD OF SN AT MOST LOCATIONS BEFORE THE SN DIMINISHES OVER THE W 09-12Z WED AND BY ABOUT 18Z WED OVER THE ERN CWA FOLLOWING DEPARTURE OF DEEP LYR QVECTOR CNVGC. MAIN NEGATIVES FOR SGNFT SN FALL INCLUDE FCST SHARPER H85-5 QVECTOR CNVGC/SHARPER H7 UVV ASSOCIATED WITH INCOMING OUT OF PHASE SHRTWVS FOCUSING TO THE S OF UPR MI... LACK OF SGNFT MSTR INFLOW WITH ONLY ABOUT 1.5-2 G/KG SPECIFIC HUMIDITY NEAR H7...AND LIMITED RESIDENCE OF TIME OF PCPN. ONE FACTOR IN FAVOR OF SOMEWHAT HIER SN AMOUNTS IS FCST DEEP DGZ THAT MAY BOOST SN/WATER RATIOS AS HI AS 20-25:1. CONSIDERING MODEL QPF 0.05-0.15 INCH...EXPECT 1 TO 3 INCHES OF SN. THE ONE EXCEPTION WL BE OVER THE ERN CWA DOWNWIND OF LK MI...WHERE INCRSG SSW FLOW UP THE LENGTH OF LK MI IN THE PRESENCE OF DEEP MSTR/H85 TEMPS ARND -15C WL BRING A PERIOD OF HEAVIER LK ENHANCED SN. PRESENCE OF LINGERING BAND IN NRN LK MI AS SHOWN ON RECENT STLT IMAGERY EARLY THIS AFTN INCREASES CONFIDENCE IN THIS FCST. BULK OF HIER RES MODELS SHOW THE HEAVIER LES BAND IMPACTING FAR SE SCHOOLCRAFT COUNTY/SRN LUCE COUNTY IN THE 09Z-15Z WED TIME FRAME. WITH MODEL QPF RANGING FM 0.25 INCH TO AS MUCH AS 0.40 INCH AND DEEP DGZ SHOWN ON THE FCST SDNGS...EXPECT AT LEAST A HI END ADVY SNFALL IN THIS AREA. FCST SDNGS ALSO SHOW A PERIOD OF NEARLY UNIDIRECTIONAL SSW FLOW WITHIN THE MIXED LYR FOR A FEW HRS DURING TIME OF PEAK SN INTENSITY. GIVEN THESE FVRBL CONDITIONS...OPTED TO UPGRADE WATCH TO A WRNG FOR LUCE COUNTY...WHERE HEAVIER LES BAND IS MOST LIKELY TO RESIDE THE LONGEST AND DROP UP TO 9 TO PERHAPS 10 INCHES ALONG M-28 E OF ERY. WENT WITH AN ADVY FOR SCHOOLCRAFT COUNTY WITH POTENTIAL FOR SOME LK ENHANCEMENT...ESPECIALLY E OF SENEY AND MANISTIQUE. AS FOR TEMPS...ARRIVAL OF THICKER CLDS/STEADY S WIND WL ALLOW FOR ONLY A RELATIVELY SMALL TEMP DIP EARLY OVER THE W HALF. BUT TO THE E...EXPECT TEMPS TO FALL QUICKLY OVER THE INTERIOR ERN CWA THIS EVNG BEFORE THE CLDS AND STEADY S WINDS ARRIVE LATER. LATER ON XMAS DAY...AS THE UPR TROF AND SFC REFLECTION SHIFT SLOWLY THRU THE UPR GREAT LKS...THE LLVL FLOW IS PROGGED TO VEER TOWARD THE W. THIS WSHFT TO A MORE WSW DIRECTION WL END THE THREAT OF LK ENHANCED SHSN OVER THE E BY EARLY AFTN BUT CAUSE SOME LES TO DVLP OVER THE W IN THE AFTN AS H85 TEMPS DIP BACK NEAR -18C BY 00Z THU. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 438 PM EST TUE DEC 24 2013 WEDNESDAY NIGHT...LOW LEVEL CONV ALONG A COLD FRONT AND 850 MB TEMPS DROPPING FROM -15C TO -19C WILL BRING AN INCREASE IN LES INTO NORTHWEST UPPER MICHIGAN WED EVENING AND OVER ERN CWA OVERNIGHT. EVEN WITH A FAVORABLE PLACEMENT OF THE DGZ IN THE CONVECTIVE LAYER GIVING SLR VALUES NEAR 25/1...INVERSION HEIGHTS NEAR 6K FT AND STEADILY VEERING WINDS SHOULD KEEP ACCUMULATIONS IN THE 2 TO 4 INCH RANGE...WITH THE GREATEST AMOUNTS IN THE HIGHER TERRAIN FROM CALUMET TO TWIN LAKES AND NORTH OF M-28 EAST OF MUNISING. THU INTO THU NIGHT...NW FLOW LES WILL GRADUALLY DIMINISH AS A WEAK SFC RIDGE BUILDS FROM THE UPPER MS VALLEY INTO THE WRN LAKES BRINGING BACKING WINDS AND LOWERING INVERSION HEIGHTS. THE STRONGEST FORCING AND MOST FAVORABLE WAA/ISENTROPIC LIFT ASSOCIATED WITH A WEAK CLIPPER SHORTWAVE TROUGH IS EXPECTED TO REMAIN SOUTH OF THE UPPER MICHIGAN. FRI...THE ECMWF WAS MORE AGGRESSIVE WITH POTENTIAL FOR SOME LIGHT SNOW BY LATE FRI WITH THE WAA/ISENTROPIC LIFT PATTERN DEVELOPING AHEAD OF THE NEXT CLIPPER SHRTWV AND SFC LOW MOVING TOWARD NW ONTARIO COMPARED TO THE GFS/GEM. WITH LOW CONFIDENCE IN ANY PCPN...ONLY SLIGHT/CHANCE POPS WERE INCLUDED...MAINLY OVER THE EAST. SAT INTO SAT NIGHT...A BRIEF WARMUP IS EXPECTED SATURDAY AS UPPER MI WILL BE IN THE WARMER SECTOR AHEAD OF THE NEXT LOW. TEMPS SHOULD CLIMB ABOVE NORMAL WITH HIGHS AROUND 30. MODEL DIFFERENCES WERE EVEN GREATER BY SATURDAY NIGHT...AS THE ECMWF WAS SLOWER/DEEPER WITH SHRTWV AND SFC LOW MOVING THROUGH THE NRN GREAT LAKES. REGARDLESS OF MODEL DIFFERENCES...A COLD FRONT MOVING THROUGH WITH WINDS VEERING SHARPLY TO THE NNW SHOULD BRING LES OR LAKE ENHANCED SNOW INTO NRN UPPER SAT NIGHT. SUN-TUE...ANOTHER VERY COLD ARCTIC AIRMASS WILL DOMINATE THE REGION THROUGH THE PERIOD WITH LES EXPECTED FOR NW WIND FAVORED SNOWBELTS. WIND CHILL VALUES NEAR ADVISORY WILL BE POSSIBLE OVER THE WEST HALF BOTH EARLY MONDAY AND TUESDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1200 AM EST WED DEC 25 2013 IFR CONDITIONS WITH LIGHT SNOW WILL CONTINUE EARLY THIS FORECAST PERIOD AS A TROF MOVES ACROSS THE AREA. AS THE SN DIMINISHES W-E BY SUNRISE ON WED...MVFR SC CIGS WL LINGER. AS THE WEAKER FLOW VEERS TOWARD THE W LATER ON WED MRNG...MORE SHSN/IFR VSBYS MAY IMPACT CMX BY EARLY WED EVENING. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 438 PM EST TUE DEC 24 2013 AS THE PRES GRADIENT TIGHTENS OVER LAKE SUPERIOR THIS EVENING BETWEEN DEPARTING SURFACE HI PRES RIDGE AND AN APPROACHING LO PRES TROF...OPTED TO MAINTAIN GOING GALE WARNING FOR THE ECENTRAL PORTIONS OF THE LAKE. AWAY FROM THIS FAVORED AREA...SOME GALE FORCE GUSTS WILL BE POSSIBLE. CLOSER APPROACH AND THEN PASSAGE OF LO PRES TROF AND WEAKER GRADIENT ON WED WILL CAUSE THE GALES TO DIMINISH AS THE WINDS VEER TOWARD THE W-NW. NORTHWEST TO NORTH GALES WILL AGAIN BE POSSIBLE SATURDAY NIGHT BEHIND AN ARCTIC COLD FRONT. HEAVY FREEZING SPRAY IS ALSO EXPECTED INTO EARLY NEXT WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR MIZ014- 085. WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MIZ007. LAKE SUPERIOR... GALE WARNING UNTIL 7 AM EST THIS MORNING FOR LSZ266. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...JLB AVIATION...07 MARINE...KC
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
338 AM CST WED DEC 25 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 337 AM CST WED DEC 25 2013 TROUGHING AND CYCLONIC FLOW WILL DOMINATE THE SHORT TERM...WHICH MEANS LOTS OF CLOUDS AND BOUTS OF LIGHT SNOW WILL DOMINATE THE NEXT 24 HOURS. LOOKING AT WATER VAPOR IMAGERY OVERLAID WITH RAP H5 VORTICITY YOU CAN SEE A COUPLE OF WAVES UPSTREAM IN THE NW FLOW THAT WILL IMPACT US. THE FIRST IS CURRENTLY OVER ERN NODAK AND ALREADY HAS SNOW MOVING ACROSS ERN SODAK AND NW MN AND WILL BE ARRIVING IN THE MPX CWA SHORTLY. THE SECOND WAVE IS UP OVER NRN SASKATCHEWAN AND WILL BE WORKING ACROSS MN THIS AFTERNOON. THESE UPPER WAVES WILL BE WORKING WITH AN ELEVATED WARM FRONT IN THE H85-H7 LAYER TO THROW SEVERAL BOUTS OF LIGHT SNOW OUR DIRECTION THROUGH THE PERIOD. THE BEST BURST WILL BE THE INITIAL ONE THIS MORNING. THE HEAVIEST SNOW HAS BEEN ALONG THAT ELEVATED WARM FRONT OVER ERN SODAK OVERNIGHT AND FOLLOWED THE HRRR FOR BRINGING THIS SNOW DOWN THE MN RIVER THIS MORNING. HAVE ENOUGH QPF OUT OF IT TO GET 0.5 TO 1 INCH SNOW AMOUNTS FROM WC MN DOWN THE MN RIVER INTO SE MN. FOR THE REST OF THE PERIOD...THE PATTERN IN PLACE LEADS TO LOW CONFIDENCE ON WHEN/WHERE THESE LITTLE BURSTS OF SNOW WILL COME DOWN...SO THERE ARE LOTS OF SMALL POPS THROUGH 9Z TONIGHT...WHICH IS WHEN THE SREF AND HIRES MODELS FINALLY SHOW SNOW CHANCES EVACUATING THE MPX CWA...FOR A SHORT TIME ANYWAYS. TEMPERATURES WILL BE TRICKY THIS PERIOD AS WELL THANKS TO A SFC WARM FRONT THAT AT 3AM WAS NEAR A ROSEAU/LONG PRAIRIE/TWIN CITIES/ALBERT LEA LINE. TEMPERATURES EAST OF THIS BOUNDARY HAVE REMAINED IN THE SINGLE DIGITS...WITH TEMPERATURES SLOWLY RISING INTO THE TEENS AND EVEN LOWER 20S BY THE TIME YOU GET TO THE MN/SD BORDER. THE COLD FRONT WAS ALIGNED FROM A WEAK SFC LOW NEAR GRAND FORKS BACK NW INTO CENTRAL SASKATCHEWAN. THE WARM SECTOR ACROSS THE DAKOTAS HAS BEEN QUITE IMPRESSIVE THIS MORNING...WITH SEVERAL LOCATIONS ACROSS THE CENTRAL DAKOTAS WARMING TO BETWEEN 32 AND 34 DEGREES /ABOUT 35 DEGREES WARMER THAN THIS TIME 24 HOURS AGO!/. THE QUESTION FOR TODAY...IS HOW MUCH OF THIS WARM SECTOR CAN WE GET INTO THE MPX CWA. THE CORE OF THE WARMEST AIR LOOKS TO DROP SOUTHWEST OF THE MPX CWA...BUT WE SHOULD STILL SEE TEMPS RISE INTO THE UPPER 20S ACROSS WRN MN THIS MORNING...BEFORE THE COLD FRONT ARRIVES THIS AFTERNOON TO START SENDING TEMPERATURES THE OTHER DIRECTION. FOR TONIGHT THE TWO VARIABLES TO WATCH ARE WHAT HAPPENS WITH CLOUD COVER AND WHERE DOES THAT COLD FRONT END UP. AS FOR THE FRONT...MOST MODELS SHOW THE FRONT BECOMING STATIONARY ACROSS SW MN...WITH ANOTHER PUNCH OF ARCTIC AIR SLIDING DOWN ACROSS AREAS MAINLY NORTH OF I-94. THIS WILL KEEP TEMPERATURES TONIGHT IN THE MN RIVER VALLEY ON SOUTH UP IN THE TEENS...BUT BACK NORTH OF I-94...IF SKIES CAN STAY SUFFICIENTLY CLEAR...WE COULD SEE MORE WIDESPREAD DOUBLE DIGIT LOWS BELOW ZERO. IT/S NOT OUT OF THE REAL OF POSSIBILITY TO SEE A NEARLY A NEARLY 30 DEGREE SPREAD IN LOWS TONIGHT ACROSS THE MPX CWA...WITH LOWS AROUND 15 ABOVE OUT IN WRN MN AND AROUND 15 BELOW ALONG THE US-8 CORRIDOR IN WRN WI. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 337 AM CST WED DEC 25 2013 THE FORECAST WARM UP FOR THE LATER HALF OF THE WEEK STILL LOOKS TO BE ON SCHEDULE. SHOULD SEE MODERATING TEMPERATURES INTO SATURDAY WITH ANOTHER WAFT OF PACIFIC AIR MOVING THROUGH...AHEAD OF NEXT ARCTIC COLD FRONT. MODELS TREND ANOTHER SHOT OF SNOW ASSOCIATED WITH THE INITIAL PACIFIC AIR INTRUSION ON THURSDAY. AT THE MOMENT...HAVE INCLUDED A SMALL LIKELY POP AREA OVER THE NORTHEAST CWA. SIGNIFICANT MOISTURE APPEARS TO BE LACKING AND MOST MODELS HAVING TROUBLE SATURATING AS THE PRECIPITATION BAND MOVES FARTHER EAST. ANY SNOWFALL SHOULD REMAIN LIGHT FOR THIS SYSTEM. DO EXPECT SOME LOWER 30S AT LEAST AHEAD OF THE ARCTIC BOUNDARY AS THAT ARRIVES SATURDAY AFTERNOON. WITH STEEP LOW LEVEL LAPSE RATES...STRONG WIND GUSTS EXPECTED TO MATERIALIZE. 35 KT WIND GUSTS LOOK LIKELY AS THE SYSTEM MOVES THROUGH. THE BETTER CHANCE OF SNOW SHOWERS SHOULD RIDE FARTHER EAST...BUT IF THEY DO COINCIDE WITH THE STRONGEST WINDS...COULD SEE NEAR BLIZZARD CONDITIONS DEVELOP OVER THE SOUTHWEST/MINNESOTA RIVER VALLEY REGION SATURDAY AFTERNOON/EVENING. HAVE CONTINUED TO INCLUDE SOME BLOWING SNOW OVER THE REGION FOR THIS PERIOD...INTO SUNDAY. THE NEXT SURGE OF ARCTIC AIR DROPS OVER THE REGION SUNDAY AND LINGERS THROUGH MUCH OF THE COMING WEEK. NORTHWEST FLOW PATTERN WILL LEAVE THE REGION IN THE FAVORABLE AREA FOR MORE LIGHT/FLUFFY SNOW EVENTS. MONDAY NIGHT INTO TUESDAY NIGHT LOOKS LIKE THE NEXT BEST CHANCE OF SOME LIGHT SNOW. HAVE LOW POPS FOR NOW. WILL HOLD OFF ON HIGHER POPS FOR NOW...TO GET BETTER TIMING AS WE GET CLOSER TO THE EVENT. WIND CHILLS WILL ONCE AGAIN BECOME AN ISSUE AS THE COLD AIR ARRIVES AS WELL. THE 00Z ECMWF SHOWS LITTLE MODERATION IN TEMPERATURES IN THE LONGER TERM...WHICH WOULD TAKE US INTO THE FIRST WEEK OF THE NEW YEAR. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1137 PM CST TUE DEC 24 2013 MVFR CONDITIONS FOR MUCH OF THE OVERNIGHT AND CHRISTMAS DAY...EXCEPT TOWARD AXN WHERE IFR WILL PREVAIL. GUIDANCE IS VERY PESSIMISTIC WITH CIGS AND VSBYS OVERNIGHT...PROBABLY DUE TO THE RESIDUAL EFFECTS OF HEAVY SNOW THIS EVENING. DO NOT BELIEVE ATTM DENSE FOG OR LIFR CIGS ARE IN THE CARDS. ANOTHER BATCH OF SNOW WILL SLIDE SOUTHEAST ACROSS MN LATE TONIGHT AND CHRISTMAS MORNING WITH A 2-3 HOUR WINDOW OF 2-4SM -SN. FOLLOWING THAT...GUSTY NORTHWEST WINDS WILL BRING A GOOD CHANCE OF BLOWING SNOW TO WESTERN MN. KMSP...CIGS WILL TEETER BETWEEN 015 AND 020 FOR MUCH OF THE OVERNIGHT...WITH SUB 015 CIGS LIKELY ACCOMPANYING THE NEXT ROUND OF SNOW EARLY WEDNESDAY. IMPROVING CONDITIONS THEREAFTER. /OUTLOOK FOR KMSP/ THU...VFR. CHANCE MVFR CIGS/VSBYS IN -SN. WINDS S AT 5 KTS. FRI...VFR. WINDS SW 5-10 KTS. SAT...VFR. CHC MVFR/-SN LATE. WINDS SW 5-10 KTS BECOMING NW 20G30 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM...DWE AVIATION...BORGHOFF
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1128 PM CST TUE DEC 24 2013 .AVIATION... 4KM WRF AND HRRR SHOW STRATUS ADVECTING NORTH ON STRONG LLVL JET. NAM/RAP SOUNDINGS ALSO INDICATE THIS ALTHOUGH GFS DOES NOT. SINCE CLOUDS ARRIVE AT METROPLEX AFTER SUNRISE HAVE INDICATED A STRATUS LAYER LIFTING TO VFR AFTER THE FROPA NEAR NOON. AT WACO SOUNDINGS INDICATE A VERY SHALLOW IFR LAYER THAT WILL ALSO BURN OFF AFTER SUNRISE. 84 && .UPDATE... A COLD FRONT CONTINUES TO MOVE SOUTH THROUGH OKLAHOMA AND THE TEXAS PANHANDLE THIS CHRISTMAS EVE. IMPRESSIVE PRESSURE RISES ON THE ORDER OF 5 TO 6 MB ACROSS THE SOUTHERN FRONT RANGE. THE FRONT SHOULD SURGE SOUTH THROUGH THE SOUTHERN HIGH PLAINS AND CHANGE ORIENTATION A BIT...BUT STILL REACH THE NORTHWEST ZONES AROUND SUNRISE. SOME PATCHY FOG WILL BE POSSIBLE AHEAD OF THE FRONT...MAINLY ACROSS THE WESTERN HALF OF NORTH TEXAS OVERNIGHT AND CHRISTMAS MORNING. THE FOG WILL NOT BE AS DENSE AS IT WAS THIS MORNING AND WE DO NOT ANTICIPATE ANY IMPACTS FROM FREEZING FOG. THE CURRENT FORECAST IS IN GOOD SHAPE OVERALL SO WILL ONLY MAKE SOME MINOR ADJUSTMENTS TO THE HOURLY GRIDS. 79 && .PREV DISCUSSION... /ISSUED 249 PM CST TUE DEC 24 2013/ AFTER A FOGGY MORNING ACROSS THE NORTHWESTERN PORTIONS OF THE FORECAST AREA...SKIES HAVE CLEARED WITH TEMPERATURES WARMING INTO THE 40S AND 50S. SOUTHERLY WINDS HAVE RETURNED WHICH HAVE HELPED WARM TEMPERATURES A FEW DEGREES VERSUS THIS TIME YESTERDAY. A SHORTWAVE TROUGH IS CURRENTLY PUSHING INTO THE CENTRAL PLAINS AND THIS TROUGH WILL SUPPORT ANOTHER FROPA FOR NORTH TEXAS TOMORROW. AHEAD OF THE FRONT...SURFACE WINDS WILL REMAIN LIGHT OVERNIGHT... AND WITH LEFT OVER LOW-LEVEL MOISTURE ANOTHER ROUND OF FOG IS POSSIBLE. DO NOT THINK VISIBILITIES WILL BE AS LOW AS THIS MORNING DUE TO SLIGHTLY HIGHER WIND SPEEDS. WILL NOT MENTION FREEZING FOG...AS LOWS IN THE NORTHWESTERN ZONES WILL BE CLOSER TO 30 AND NOT IN THE UPPER 20S...SO CHANCES FOR IMPACTS WOULD BE LOWER AS WELL. THE FOLLOWING SHIFTS MAY NEED TO ASSESS OR CHANGE THE FORECAST IF DENSE FOG LOOKS MORE LIKELY OR TEMPERATURES BECOME COLDER THAN FORECASTED. THE FRONT IS EXPECTED TO PUSH INTO THE AREA LATE TOMORROW MORNING AND AFTERNOON. STRONG VERTICAL MOTIONS WILL BE OCCURRING ACROSS THE AREA AS THE TROUGH NEARS THE REGION OVERNIGHT AND TOMORROW...BUT MOISTURE REMAINS SCOURED AS THE GULF OF MEXICO REMAINS SHUT OFF. THEREFORE...NO RAIN IS EXPECTED WITH THIS FRONT. THE FRONT WILL ACTUALLY HAVE LITTLE IMPACT TO OUR WEATHER. HIGHS FRIDAY WILL BE INTO THE UPPER 50S WITH LOWER 60S BY SATURDAY AFTERNOON. ANOTHER PIECE OF ENERGY WILL MOVE INTO THE REGION FRIDAY...BUT NO RAIN IS EXPECTED. WITH ONE FROPA AFTER ANOTHER...MOISTURE WILL REMAIN TOO LOW TO SUPPORT PRECIPITATION. A LARGER TROUGH IS EXPECTED TO DROP INTO THE CENTRAL AND EASTERN CONUS SATURDAY AND SUNDAY. THIS TROUGH WILL SEND YET ANOTHER...AND STRONGER COLD FRONT INTO THE FORECAST AREA SUNDAY. OVER THE PAST DAY OR TWO...WE HAVE BEEN TALKING ABOUT THE CHANCES FOR LIGHT RAIN OR DRIZZLE IN THE EASTERN ZONES WITH THE FROPA...BUT THIS SEEMS LESS LIKELY. LATEST FORECAST SOUNDINGS SHOW SATURATION OF THE LOWER LEVELS OF THE ATMOSPHERE WILL NOT OCCUR UNTIL AFTER FROPA AND WINDS WITHIN THIS LAYER WILL ALREADY BE NORTHERLY BY THE TIME SATURATION OCCURS. THIS WOULD SUPPORT DOWNWARD MOTIONS AND WOULD NOT LEAD TO THE PRODUCTION OF PRECIPITATION. THIS FRONT WILL KEEP TEMPERATURES COLDER THAN NORMAL...WITH FREEZES EXPECTED FOR MUCH OF THE AREA MONDAY AND TUESDAY MORNING. HAMPSHIRE && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 32 52 32 54 34 / 0 0 0 0 0 WACO, TX 32 54 33 54 32 / 0 5 0 5 5 PARIS, TX 28 50 30 54 31 / 0 0 0 0 5 DENTON, TX 32 51 29 54 31 / 0 0 0 0 0 MCKINNEY, TX 29 51 30 54 31 / 0 0 0 0 0 DALLAS, TX 34 52 33 54 35 / 0 0 0 0 0 TERRELL, TX 31 53 31 54 31 / 0 0 0 0 5 CORSICANA, TX 32 56 33 54 33 / 0 5 0 5 5 TEMPLE, TX 32 55 34 55 33 / 0 5 0 5 5 MINERAL WELLS, TX 31 52 28 55 30 / 0 0 0 0 0 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ / Area Forecast Discussion National Weather Service Lincoln IL 949 AM CST Wed Dec 25 2013 .DISCUSSION... ISSUED 948 AM CST Wed Dec 25 2013 Initial upper wave currently pushing through central Illinois. Earlier light snow ahead of this wave is now well off to the west. However, a faster shortwave, currently diving into northwest Iowa, has been producing some light snow ahead of it, from central Iowa to western Wisconsin. Morning models showing the bulk of the snow with this feature tracking just to our north, but the NAM and RAP models show potential for perhaps a tenth or two of snow north of I-74 during the evening hours. Have made some updates to the snow trends in the forecast, namely to add some low PoP`s in the far northern CWA this evening. Have also removed most of the flurries after midnight, as the shortwave should be well east of us by that point. Temperature forecasts generally on track and only needed some minor tweaks. Geelhart && .AVIATION... ISSUED 556 AM CST Wed Dec 25 2013 MVFR clouds will prevail for the first few hours of this TAF period as a fast moving clipper produces light snow for a period of an hour or so. Snow has already ended at PIA, and is just affecting SPI. Over the next 2 hours, BMI, DEC and CMI will see the snow move through. IFR clouds are poised to develop 2 hours after the snow ends, based on observation trends upstream. The NAM and RAP soundings show IFR conditions could persist into the afternoon, and possibly until near sunset. MVFR conditions could develop as mixing increases this afternoon, but we generally held off the return to MVFR clouds until 22-23z. Some clearing should develop from west to east this evening, as the drier air returns to lower levels. Clearing could reach PIA as early as 01z and progress to CMI by 07z. Winds will be primarily southwest until this evening when they shift to the west and increase from around 10-12kt to 14-16kt. Shimon && .PREV DISCUSSION... ISSUED 209 AM CST Wed Dec 25 2013 No major storm systems are anticipated across central Illinois over the next week, as a prevailing northwesterly flow pattern brings periodic flurries/very light snow and bouts of very cold air. SHORT TERM...Today through Friday First weak system embedded within the northwesterly flow is currently approaching the Mississippi River as an elongated vorticity max stretching from Wisconsin to the Texas panhandle. This feature has been shearing/weakening as it tracks eastward, and with limited moisture to work with, has produced only very meager amounts of light snow across parts of central and northern Iowa. Stronger lift and steadier snows have been confined further north across Minnesota into Wisconsin. Despite models insisting on precip development further south, have not seen much evidence upstream over Missouri, so have decided to downplay the snow chances this morning. Will maintain low chance PoPs along/north of the I-74 corridor through midday, where a dusting is possible. Further south, will only mention scattered flurries across the remainder of the KILX CWA. Once the initial wave passes, another disturbance currently dropping into North Dakota will skirt across northern Illinois this evening. Due to increasing synoptic lift ahead of this feature, have added flurries to the forecast along/west of the Illinois River late this afternoon, then everywhere tonight. Upper pattern will begin to go zonal by the end of the week, signaling a brief warming trend that will help boost highs well into the 30s and even the lower 40s south of I-70 by Friday. LONG TERM...Saturday through Tuesday Warmest day of the forecast period will be Saturday, as southwesterly winds ahead of an approaching Arctic cold front allow temps to reach the 40s across the board. Models have been consistent in bringing the cold front through central Illinois on Sunday, with each run suggesting clouds and perhaps a few snow-showers. Will carry low chance PoPs for snow on Sunday accordingly. Once front passes, another chunk of very cold air will arrive early next week as the upper flow pattern returns to northwesterly. With 850mb temps progged to fall into the -12 to -14C range, highs will drop back into the teens and lower 20s by Monday. After that, will have to watch the next approaching clipper system for late Monday into Tuesday. Latest models are slower and a bit further north with this system, but still suggest a period of light snow will be possible across the northern CWA late Tuesday. Timing of these features this far out is quite difficult, so will only mention very low chance POPs across the north at this time. Barnes && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
802 AM CST WED DEC 25 2013 .DISCUSSION... 330 AM CST SYNOPSIS...A COUPLE QUICK SNOW SYSTEMS MOVE ACROSS THE REGION THROUGH TONIGHT WITH 1 TO 2 INCHES EXPECTED PRIMARILY ALONG AND NORTH OF I-88. A BRIEF WARM UP IS EXPECTED LATE THIS WEEK BEFORE TEMPERATURES QUICKLY TUMBLE SUNDAY WITH ANOTHER CHANCE OF SNOW. FOR EXAMPLE HIGH TEMPS SATURDAY WILL BE IN THE MID 30S TO THE LOW 40S THEN LOW TEMPS SUNDAY NIGHT WILL VARY FROM -6 TO +8 ACROSS THE CWA. ADDITIONAL CHANCES OF SNOW ARRIVE EARLY NEXT WEEK...WITH TUESDAYS SYSTEM LOOKING THE MOST IMPRESSIVE. TODAY AND TONIGHT... THE LONGWAVE TROUGH AXIS STRETCHES FROM MINNESOTA THROUGH NEW MEXICO THIS MORNING WITH A SHORTWAVE TRAVELING A BIT QUICKER THAN THE LARGER WAVE. THE SHORTWAVE IS OVER EASTERN IOWA AND ASSOCIATED WITH SOME LIGHT RETURNS ON RADAR ALONG THE IL/IA STATE LINE. GUIDANCE CONTINUES TO BACK OFF ON HOW MUCH SNOW WILL DEVELOP AHEAD OF THE SHORTWAVE...BUT DECIDED TO KEEP SNOW GOING IN THE FORECAST. TEMPS HAVE COME UP TO AROUND 20 DEGREES WITH THE DGZ AT OR NEAR THE SURFACE. FORCING EXTENDS THROUGH THE DGZ FOR A COUPLE OF HOURS WITH A SATURATED SOUNDING AT THOSE LAYERS. HOWEVER...GIVEN THE DOWN PLAY IN GUIDANCE AND HOW SNOW IS STRUGGLING TO DEVELOP NOW...LOWERED STORM TOTAL SNOW AMOUNTS. WENT FOR AN INCH NORTH OF I-88...ESPECIALLY ALONG THE IL/WI STATE LINE...WITH AN INCH OR LESS EXPECTED SOUTH OF THAT. SOUTH TO SOUTHWEST WINDS GUSTING UP TO 20 KT COULD RESULT IN A LITTLE BLOWING SNOW...BUT NOT OVERLY CONCERNED SINCE ONLY EXPECTING AN INCH TODAY. THE SNOW THAT DOES FALL WILL BE VERY DRY WITH RATIOS IN EXCESS OF 20:1. HIGH TEMPS WILL BE AT FREEZING DOWN SOUTH TO THE MID 20S ALONG THE WI/IL STATE LINE. HOWEVER...WIND CHILLS WILL MAKE IT FEEL LIKE SINGLE DIGITS ALONG THE WI/IL STATE LINE TO THE TEENS DOWN SOUTH. NEXT UP IS THE LOW CURRENTLY STRETCHING FROM HUDSON BAY THROUGH NORTHWEST MINNESOTA. THE LOW PASSES OVER ONTARIO THIS AFTERNOON WITH THE UPPER LEVEL TROUGH AXIS PASSING THROUGH THIS AFTN/EVENING. EXPECTING ANOTHER BATCH OF SNOW SHOWERS TO FORM AHEAD OF THIS AS WELL. HAVE SNOW ENTERING NORTH CENTRAL IL THIS AFTN WITH A BAND SPREADING SOUTH EAST THROUGH THIS EVENING. THE DEPTH OF MOISTURE IN THE DGZ IS MUCH BETTER WITH THIS SECOND DISTURBANCE AND COULD SEE A QUICK HALF INCH TO INCH THROUGH THIS EVENING. THE HIGHEST TOTALS ARE AGAIN EXPECTED ALONG THE IL/WI STATE LINE BECAUSE THE FORCING STARTS OUT FARTHER NORTH AND DOES NOT MOVE INTO IL UNTIL THE MOISTURE IS OVER INDIANA AND MICHIGAN. FOR OVERNIGHT DID NOT MAKE ANY MAJOR CHANGES TO GOING LOW TEMPS. NOT SURE HOW MUCH OF THE AREA WILL HAVE A FRESH SNOWPACK SO TEMPS MAY HAVE TO BE LOWERED A BIT BY LATER SHIFTS. COLDER AIR ALOFT MOVES IN BEHIND THE TROUGH AXIS...LESS THAN -8C AT 925 MB...AND CLOUDS SHOULD THIN LATE TONIGHT. SO UPPER TEENS DOWN SOUTH TO SINGLE DIGITS ACROSS NORTH CENTRAL IL IS EXPECTED. OVERNIGHT...MIN WIND CHILLS WILL BE IN THE SINGLE DIGITS DOWN SOUTH TO AS LOW AS -10F NORTH OF I-88. THURSDAY AND FRIDAY... NORTHWEST FLOW ALOFT IS EXPECTED EARLY THURSDAY BUT ANOTHER TROUGH AXIS ROLLS THROUGH FRIDAY. AT THE SURFACE HIGH PRESSURE BUILDS ACROSS THE SOUTHERN U.S. WITH ITS RIDGING PASSING OVER THE REGION THURSDAY AFTN. KEPT A DRY FORECAST GOING FOR THIS PERIOD. SOUTHWEST FLOW AND WAA RAISE 925 MB TEMPS TO NEAR 0C BY FRIDAY MORNING...AND THEN TO AROUND +5 BY SATURDAY MORNING. THEREFORE HAVE TEMPS INCREASING THROUGH FRIDAY TO AROUND 30 ALONG THE IL/WI STATE LINE TO NEAR 40 ACROSS THE SOUTHERN PORTION OF THE CWA. OVERNIGHT LOWS FRIDAY LOOK TO BE IN THE 20S. SATURDAY AND SUNDAY... THE NEXT WEAK LOW IS PUSHED SOUTH THROUGH THE CWA SATURDAY EVENING AND NIGHT WITH THE UPPER LEVEL TROUGH AXIS ROTATING THROUGH SUNDAY NIGHT. THE WARM UP CONTINUES ON SATURDAY...AND TEMPERATURES MAY HAVE TO BE RAISED FURTHER SINCE GUIDANCE CONTINUES TO SUGGEST 925MB TEMPS WILL WARM TO +4 TO +8C SATURDAY AFTERNOON. THAT RELATES TO MAX TEMPS ON SATURDAY OF IN THE MID 30S TO LOW 40S. NOT EXPECTING ANY PRECIP UNTIL BEHIND THE LOW AND ITS COLD FRONT/UPPER LEVEL TROUGH AXIS SUNDAY. FIRST...TEMPERATURES DROP THROUGH THE DAY ON SUNDAY WITH HIGH TEMPS BEING MET EARLY SUNDAY MORNING. LOOKING AT TEMPS RANGING FROM SINGLE DIGITS NEAR RFD TO LOW 20S IN NORTHWEST INDIANA BY EARLY SUNDAY EVENING. SO EXPECTING ANY PRECIP THAT DOES FORM SHOULD BE SNOW. TEMPS CONTINUE TO FALL WITH 925MB TEMPS AT -15 TO -20C BY MONDAY MORNING. THEREFORE LOW TEMPS SUNDAY NIGHT WILL RANGE FROM THE SINGLE DIGITS TO AROUND -5F. NORTHWEST WINDS AROUND 10 KT WILL CREATE MIN WIND CHILLS BELOW ZERO SUNDAY NIGHT. THE COLDEST AREA WILL BE NORTH OF I-88 WHERE WIND CHILLS LOWER THAN -20F ARE POSSIBLE. FOR SNOW...THE FORCING AND MOISTURE DO NOT SEEM ALL THAT IMPRESSIVE AT THIS TIME SO NOT EXPECTING ANY MAJOR ACCUMULATION. GFS COBB OUTPUT AGREES AS IT IS ONLY SHOWING A FEW TENTHS. EXTENDED...MONDAY AND TUESDAY... MONDAY REMAINS COLD AS THE UPPER LEVEL COLD AIR LINGERS OVERHEAD...BUT WINDS TURN WSW AND BEGIN TO USHER IN WARMER AIR ALOFT MONDAY NIGHT. HIGH TEMPS ON MONDAY WILL BE IN THE SINGLE DIGITS TO THE LOWER TEENS AND WIND CHILLS DURING THE DAY BELOW ZERO. MIN WIND CHILLS MONDAY NIGHT WILL ONCE AGAIN BE BELOW ZERO. HIGH PRESSURE PASSES OVER MONDAY NIGHT WITH ANOTHER CLIPPER ARRIVES TUESDAY. THIS SYSTEM LOOKS DARE I SAY VIGOROUS...FOR BEING A WEEK AWAY. GUIDANCE DIFFERS SLIGHTLY SO ONLY UPPED POPS INTO THE CHANCE RANGE...BUT LOOKING AT LONG RANGE COBB FOR FUN INDICATES SNOWFALL OF A FEW INCHES. JEE && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * 1000-1500 FT CIGS THROUGH MUCH OF TODAY WITH THE POTENTIAL TO DIP DOWN TO IFR AT TIMES AFTER 16Z. * CHANCE FOR LIGHT SNOW THIS AFTERNOON AND EVE. BEACHLER/MTF //DISCUSSION...UPDATED 12Z... BACK EDGE OF CLIPPER CONTINUES TO SLIDE EAST ACROSS THE NORTHERN IL/NORTHWEST IN AIRFIELDS. REGIONAL RADAR DEPICTION INDICATES THE BACK EDGE OF THE PRECIP WILL BE NEARING ORD/MDW BETWEEN 12-13Z. CIGS WILL THEN LINGER ARND LOW END MVFR...POSSIBLY DIP TO IFR MID- MORNING THRU EARLY AFTN. WINDS REMAIN SOUTHERLY WITH OCCASIONAL GUSTS TO 15-19KT...SOME DRY AIR EVENTUALLY WORKS BACK INTO THE AREA MIDDAY AND ALLOWS CIGS TO LIFT SLIGHTLY BUT REMAIN MVFR. THEN YET ANOTHER CLIPPER IS POISED TO ARRIVE AFT 22Z...WITH LIGHT SNOW DEVELOPING ARND 00-03Z THUR. WINDS THEN VEER TO WEST ARND 10-12KT THRU DAYBREAK THUR. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 14Z... * HIGH CONFIDENCE IN CIGS REMAINING AT OR BELOW 1500 FT THROUGH EARLY AFTERNOON. LOW CONFIDENCE ON WHETHER IFR WILL BE REACHED. * HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS. * LOW/MEDIUM CONFIDENCE IN LGT SNOW DEVELOPING AFT 22Z. BEACHLER/MTF //OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z... THURSDAY NIGHT...MAINLY VFR. POSSIBLE PATCHY MVFR CIGS. THU THROUGH MON...VFR. SLT CHC -SN ON SUN AS WELL AS MON NIGHT. TUESDAY...SLT CHC -SN. BEACHLER && .MARINE... 302 AM CST HAZARDOUS WAVES/WINDS WILL FOR THE NEARSHORE WATERS AND MAY ALSO SEE OCCASIONAL GALE FORCE GUSTS IN THE NEARSHORE WATERS THRU MIDDAY. SFC RIDGE CENTERED OVER THE OHIO VALLEY CONTINUES TO DRIFT EAST TOWARDS THE MIDDLE ATLANTIC REGION...STRETCHING NORTH TO QUEBEC. MEANWHILE A TROUGH OF LOW PRESSURE OVER THE UPPER MIDWEST WILL SLIDE NORTHEAST TOWARDS CENTRAL ONTARIO THIS MORNING...THEN SLOWLY LIFT NORTHEAST ACROSS JAMES BAY BY EARLY THURSDAY MORNING. THE GRADIENT THAT WAS EXPECTED TO DEVELOP AND PRODUCE THE GALES DEVELOPED BUT REMAINED WELL NORTH OF THE LAKE ACROSS LAKE SUPERIOR...HOWEVER SOME REPORTS ACROSS THE FAR NORTHERN PORTION OF LAKE MICHIGAN INDICATE LOW END GALES. SO GIVEN THE REDUCED CONFIDENCE IN THE GALES AND LACK OF OBSERVATIONS TO SUPPORT KEEPING THE GALE WARNING GOING...HAVE OPTED TO CANCEL THE GALE WARNING EARLY. WILL HOWEVER CONTINUE TO MENTION OCCASIONAL GALE FORCE GUSTS TO 35 KT THROUGH MID MORNING...THEN THE GRADIENT WILL CONTINUE TO WEAKEN. WINDS WILL STEADILY SHIFT FROM SOUTHWEST TO WEST BY LATE THIS AFTERNOON...THEN CONTINUE TO DIMINISH TO AROUND 15 TO 25 KT. HAZARDOUS WINDS AND WAVES WILL PERSIST FOR THE NEARSHORE WATERS AND CONFIDENCE REMAINS HIGH THAT THE SMALL CRAFT ADVISORY WILL CONTINUE. IT IS POSSIBLE THAT THE SMALL CRAFT ADVISORY WILL NEED TO BE EXTENDED FOR THE INDIANA NEARSHORE WATERS AS WINDS TURN WEST...THIS MAY HELP KEEP ELEVATED WAVES LONGER FOR THIS FAR SOUTHEAST CORNER OF LAKE MICHIGAN. THE NEXT WEATHER SYSTEM TO BRING A STRONG GRADIENT TO THE LAKE WILL ARRIVE SAT...AND LIKELY PRODUCE WINDS TO 30KT. IT IS POSSIBLE A FEW GUSTS TO GALE FORCE MAY OCCUR SAT. THEN ANOTHER STRONG RIDGE OF HIGH PRESSURE WILL SLIDE SOUTH FROM CENTRAL CANADA FOR THE SECOND HALF OF THE WEEKEND AND MAY BRING A TIGHT GRADIENT TO THE LAKE. SFC RIDGE OVER THE OHIO VALLEY WILL CONTINUE TO DRIFT EAST TONIGHT...WITH A TIGHTENING GRADIENT ALONG THE WESTERN EDGE. THIS TIGHT GRADIENT WILL SLIDE OVER THE LAKE TONIGHT...PRODUCING SOUTH/SOUTHWEST GALES BETWEEN 35-40KT OVERNIGHT. THE GRADIENT CONTINUES TO SLIDE EAST WITH THE ARRIVAL OF A CLIPPER LOW PRESSURE. THIS CLIPPER WILL ALLOW THE WINDS TO BECOME WESTERLY...AND SHOULD SEE GALES COME TO AN END BY MID-MORNING WED. HOWEVER THE GRADIENT WILL REMAIN RELATIVELY STRONG AND PRODUCE WINDS TO 30KT THRU MIDDAY WED BEFORE DIMINISHING TO 15 TO 25 KT BY WED NIGHT. THE NEXT WEATHER SYSTEM TO BRING A STRONG GRADIENT TO THE LAKE WILL ARRIVE SAT...AND LIKELY PRODUCE WINDS TO 30KT. IT IS POSSIBLE A FEW GUSTS TO GALE FORCE MAY OCCUR SAT. THEN ANOTHER STRONG RIDGE OF HIGH PRESSURE WILL SLIDE SOUTH FROM CENTRAL CANADA FOR THE SECOND HALF OF THE WEEKEND AND MAY BRING A TIGHT GRADIENT TO THE LAKE. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 10 PM WEDNESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 556 AM CST Wed Dec 25 2013 .DISCUSSION... ISSUED 209 AM CST Wed Dec 25 2013 No major storm systems are anticipated across central Illinois over the next week, as a prevailing northwesterly flow pattern brings periodic flurries/very light snow and bouts of very cold air. SHORT TERM...Today through Friday First weak system embedded within the northwesterly flow is currently approaching the Mississippi River as an elongated vorticity max stretching from Wisconsin to the Texas panhandle. This feature has been shearing/weakening as it tracks eastward, and with limited moisture to work with, has produced only very meager amounts of light snow across parts of central and northern Iowa. Stronger lift and steadier snows have been confined further north across Minnesota into Wisconsin. Despite models insisting on precip development further south, have not seen much evidence upstream over Missouri, so have decided to downplay the snow chances this morning. Will maintain low chance POPs along/north of the I-74 corridor through midday, where a dusting is possible. Further south, will only mention scattered flurries across the remainder of the KILX CWA. Once the initial wave passes, another disturbance currently dropping into North Dakota will skirt across northern Illinois this evening. Due to increasing synoptic lift ahead of this feature, have added flurries to the forecast along/west of the Illinois River late this afternoon, then everywhere tonight. Upper pattern will begin to go zonal by the end of the week, signaling a brief warming trend that will help boost highs well into the 30s and even the lower 40s south of I-70 by Friday. LONG TERM...Saturday through Tuesday Warmest day of the forecast period will be Saturday, as southwesterly winds ahead of an approaching Arctic cold front allow temps to reach the 40s across the board. Models have been consistent in bringing the cold front through central Illinois on Sunday, with each run suggesting clouds and perhaps a few snow-showers. Will carry low chance POPs for snow on Sunday accordingly. Once front passes, another chunk of very cold air will arrive early next week as the upper flow pattern returns to northwesterly. With 850mb temps progged to fall into the -12 to -14C range, highs will drop back into the teens and lower 20s by Monday. After that, will have to watch the next approaching clipper system for late Monday into Tuesday. Latest models are slower and a bit further north with this system, but still suggest a period of light snow will be possible across the northern CWA late Tuesday. Timing of these features this far out is quite difficult, so will only mention very low chance POPs across the north at this time. Barnes && .AVIATION... ISSUED 556 AM CST Wed Dec 25 2013 MVFR clouds will prevail for the first few hours of this TAF period as a fast moving clipper produces light snow for a period of an hour or so. Snow has already ended at PIA, and is just affecting SPI. Over the next 2 hours, BMI, DEC and CMI will see the snow move through. IFR clouds are poised to develop 2 hours after the snow ends, based on observation trends upstream. The NAM and RAP soundings show IFR conditions could persist into the afternoon, and possibly until near sunset. MVFR conditions could develop as mixing increases this afternoon, but we generally held off the return to MVFR clouds until 22-23z. Some clearing should develop from west to east this evening, as the drier air returns to lower levels. Clearing could reach PIA as early as 01z and progress to CMI by 07z. Winds will be primarily southwest until this evening when they shift to the west and increase from around 10-12kt to 14-16kt. Shimon && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1044 AM EST WED DEC 25 2013 .UPDATE... ISSUED AT 1043 AM EST WED DEC 25 2013 CANX GOING WARNING FOR LUCE COUNTY EARLY GIVEN EXIT OF ENHANCED CLD SHOWN ON IR STLT LOOP AND SHIFT OF HEAVY LES BAND TO THE E INTO CHIPPEWA COUNTY PER CNDN MONTREAL RIVER RADAR. NEARBY SFC OBS ALSO SHOW A WSHFT TO THE WSW AT ERY AND NAUBINWAY...CONSISTENT WITH THE PASSAGE OF THE HEAVIER BAND TO THE E. SOME SCT SHSN WL CONT THRU THE DAY IN LUCE COUNTY...BUT ANY ADDITIONAL ACCUM SHOULD BE LESS THAN AN INCH. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 531 AM EST WED DEC 25 2013 PARADE OF SHORTWAVES IN STORE ACROSS UPPER GREAT LAKES FOR NEXT 24 HOURS AS UPR LAKES REMAINS ON PERIFERY OF MEAN TROUGH. LEAD SHORTWAVE AND MOISTURE ADVECTION HAS RESULTED IN WIDESPREAD SNOW WEST TO EAST ACROSS UPR MICHIGAN. LIMITED REPORTS BUT SEEMS MOST SNOW /2-3 INCHES/ OCCURRED IN SCNTRL CWA ON NORTHERN FRINGE OF BETTER DEEP LAYER Q-VECTOR CONVERGENCE. OTHER AREA OF HIGHER SNOWFALL IS DUE TO LAKE ENHANCEMENT OFF LK MICHIGAN OVER FAR EAST CWA...JUST TO EAST OF MANISTIQUE TOWARD NEWBERRY. MQT AND APX RADARS SHOWED MAIN BAND OF LAKE EFFECT AS EARLY AS 06Z WITH ECHOES OVER NORTHERN LK MICHIGAN UP TO 10KFT SUGGESTING HEALTHY BAND OF SNOW. HAVING TO DO A LOT OF INTERPOLATION AND EXTRAPOLATION IN DETERMINING WHAT IS GOING ON IN THSES AREAS USING MDOT WEBCAMS AND FREQUENT CALLS TO THE ISQ AND ERY AWOS /LONG-LINE TRANSMISSION OF MANY AWOS ACROSS THE REGION IS DOWN RIGHT NOW/. WILL HAVE TO WAIT TO GET REPORTS LATER THIS MORNING...BUT AS BEST WE CAN TELL SEEMS THE HEAVIEST AND MOST PERSISTENT SNOW HAS OCCURRED FROM NEAR BLANEY PARK TOWARD MCMILLAN IN SOUTHWEST LUCE COUNTY. JUST WITHIN LAST HOUR...HEAVY SNOW IS PUSHING TOWARD NEWBERRY. GEM-REGIONAL AND HRRR PEGGING THINGS PRETTY WELL. BOTH SHOW THE MAIN CONVERGENCE BAND AND HEAVY SNOW MOVING STEADILY TO THE EAST THIS MORNING...PROBABLY OUT OF ERY BY 15Z IF NOT SOONER. LOWERED SNOW AMOUNTS SLIGHTLY OVER SOUTHERN LUCE...BUT OVERALL WILL KEEP HEADLINES AS IS FOR NOW AS WINDS ALONG LK MICHIGAN SHOWING GUSTS OVER 30 MPH /PROBABLY REPRESENTATIVE WHAT IS OCCURRING WITHIN THE SNOW BAND FARTHER INLAND/ WHICH WOULD BE RESULTING IN BLOWING AND DRIFTING OF THE SNOW. WILL RE-EVALUATE THE HEADLINES TOWARD DAYBREAK TO SEE IF SOME CHANGES ARE NEEDED. ELSEWHERE...EXPECT THE WIDESPREAD SNOW TO TAPER OFF BY DAYBREAK. GUSTY WINDS COULD EASILY BLOW THE FLUFFY SNOW AROUND SO PUT OUT AN SPS MAINLY EMPHASIZING DIFFICULT TRAVEL IN SOME AREAS THIS MORNING. LATER TODAY...ANOTHER SHORTWAVE CURRENTLY SLIDING ACROSS MINNESOTA MAY RESULT IN A CONTINUATION OF SOME LGT SNOW OR FLURRIES FOR MOST OF THE AREA. INTO TONIGHT...EMPHASIS FOR LAKE EFFECT SHIFTS TO THE SNOWBELTS OF WESTERN AND EVENTUALLY FAR NORTHEAST UPR MICHIGAN...MAINLY EAST OF MUNISING AND TO THE NORTH OF NEWBERRY. LAST SHORTWAVE FAIRLY STRONG BUT DIRECT IMPACTS MOSTLY STAY TO THE SOUTH OF UPR MICHIGAN AS WAVE TRACKS FM CNTRL MN ACROSS WI. WAVE MAY ACT TO HOLD TROUGHING IN PLACE OVER SCNTRL LK SUPERIOR RESULTING IN MAINLY WSW WINDS OVER MUCH OF THE LAND AREAS AND NW WINDS OVER LK SUPERIOR. FOR THIS REASON...LEANED TOWARD NCEP WRF-ARW/NMM IDEA OF CONVERGENCE BAND TRYING TO GET GOING OVER THE KEWEENAW TOWARD EASTERN ALGER COUNTY AFTER LATE EVENING. SOUNDINGS FOR TONIGHT SHOW DRYING AND SUBSIDENCE ABOVE H8 BUT BULK OF LAKE EFFECT CONVECTIVE LAYER IS WELL WITHIN THE DGZ RESULTING IN SLR/S SOLIDLY OVER 20:1 AND MAYBE PUSHING TOWARD 30:1. IF CONVERGENCE IS STRONGER...MAY SEE ADVY LEVEL SNOW AMOUNTS FOR PORTIONS OF KEWEENAW AND PERHAPS AS FAR SOUTH AS HIGHER TERRAIN OF NORTHERN ONTONAGON COUNTY...INCLUDING WHITE PINE AND ROCKLAND. SINCE IT WILL BE VERY FLUFFY SNOW AND WINDS/BLSN WILL NOT BE TOO MUCH OF A FACTOR AND SINCE SOME PLACES IN KEWEENAW ARE WELL OVER 100 INCHES ALREADY FOR SEASON...EVENT DOES NOT APPEAR TO SUPPORT THE NEED FOR ADVY AS IT STANDS NOW. DAYSHIFT CAN RE-EVALUATE BUT DID NOT ISSUE AT THIS TIME. HEAVIER LAKE EFFECT WILL ALSO AFFECT THE SNOWBELTS OF THE NORTHEAST CWA WITH MOST SNOW NOT OCCURRING UNTIL WELL AFTER MIDNIGHT ONCE WINDS SHIFT MORE WNW. INLAND FROM THE LAKE EFFECT ISSUES...SKIES MAY TRY TO CLEAR OUT IF THE WINDS ARE MORE WSW THAN WNW. IF THIS OCCURS...TEMPS OVER INLAND WEST AND CNTRL AND MAYBE EVEN EASTERN CWA COULD FALL WELL BELOW ZERO. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 531 AM EST WED DEC 25 2013 WARMING WILL OCCUR LATE THIS WEEK AS FLOW BRIEFLY BECOMES ZONAL ACROSS THE NRN CONUS. HOWEVER...OVER THE NEXT 7 DAYS...THE CURRENT RATHER DISORGANIZED POLAR VORTEX LOCATED WELL N IN NRN CANADA WILL REORGANIZE/EXPAND AND DROP S TO THE VCNTY OF HUDSON BAY. AS A RESULT...ARCTIC AIR WILL AGAIN SPREAD S INTO THE UPPER GREAT LAKES NEXT WEEK...AND THERE MAY BE A COUPLE OF SHOTS OF BITTER COLD AIR. PATTERN DOES NOT LOOK FAVORABLE FOR MUCH IN THE WAY OF WIDESPREAD SYNOPTIC SNOWFALL OVER THE NEXT 7 DAYS. NEXT WEEK...LES WILL BE THE MAIN PCPN CONCERN...MOSTLY FOR SNOWBELTS FAVORED BY W TO NW WINDS. BEGINNING THU...WNW FLOW LES WILL GRADUALLY DIMINISH AS WEAK SFC HIGH PRES RIDGE MOVES FROM THE UPPER MISSISSIPPI VALLEY TOWARD THE UPPER LAKES. DGZ OCCUPIES A GOOD PORTION OF THE CONVECTIVE LAYER... SO MIGHT BE ABLE TO FLUFF UP SEVERAL INCHES OF SNOW ACCUMULATION THU. BEST ACCUMULATIONS SHOULD OCCUR IN FAR NRN ONTONAGON/CNTRL HOUGHTON COUNTIES DUE TO CONVERGENT WRLY FLOW INTO THAT AREA AND ALSO ERN ALGER/NRN LUCE COUNTIES WHERE MODELS DEPICT RATHER STRONG LOW-LEVEL CONVERGENCE. ADVY TYPE HEADLINE MAY BE REQUIRED FOR THE LATTER AREA. WITH PASSAGE OF SFC HIGH PRES RIDGE THU NIGHT...LINGERING LES WILL END AS WINDS SHIFT SW/OFFSHORE. FAVORED THE LOWER SIDE OF GUIDANCE FOR MIN TEMPS WITH AT LEAST A PERIOD OF LIGHT WINDS AND PARTLY CLOUDY SKIES IN MOST AREAS. WAA PATTERN WILL BE IN FULL SWING FRI AS PACIFIC AIR SPREADS OUT ACROSS THE NRN PLAINS IN DEVELOPING ZONAL FLOW. MIGHT BE A LITTLE PCPN ACROSS NRN UPPER MI...BUT BETTER PCPN POTENTIAL WILL BE FARTHER N WHERE SUFFICIENT LOW-LEVEL MOISTENING IS MORE LIKELY. TEMPS WILL REACH THE 20S ACROSS THE BOARD. WARMING WILL CONTINUE SAT AHEAD OF A SHORTWAVE TRACKING FROM BC/PACIFIC NW TO THE NRN PLAINS. MOST LOCATIONS SHOULD TOP OUT AROUND 30F. HOWEVER...A COLD FRONT DRIFTING S ACROSS UPPER MI WILL INFLUENCE MAX TEMPS DEPENDING ON ITS TIMING. UPPER DIVERGENCE ASSOCIATED WITH RIGHT ENTRANCE OF UPPER JET TO THE N AND NE SHOULD SUPPORT A RIBBON OF -SN BEHIND THE SOUTHWARD DRIFTING COLD FRONT. THAT -SN SHOULD BEGIN TO AFFECT NW UPPER MI SAT AFTN. AS COLD FRONT CONTINUES TO DROP S SAT NIGHT/SUN MORNING...EXPECT MOST OF THE FCST AREA TO SEE SOME -SN...AIDED BY RIGHT ENTRANCE UPPER DIVERGENCE. SOME LAKE ENHANCEMENT SEEMS LIKELY FOR MOST IF NOT ALL OF NRN UPPER MI AS WINDS WILL LIKELY SHIFT N FOR A TIME BEHIND COLD FRONT AND POTENTIAL WEAK SFC WAVE THAT WILL ALSO BE TRACKING ALONG FRONT. BEHIND THE COLD FRONT AND WITH THE PASSAGE OF ANOTHER SHORTWAVE ROTATING THRU THE UPPER LAKES AROUND EXPANDING POLAR VORTEX...MUCH COLDER AIR WILL DUMP INTO THE UPPER LAKES SAT NIGHT/SUN. THIS WILL RESULT IN NW FLOW LES TAKING OVER SUN AS 850MB TEMPS PLUMMET INTO THE LOW/MID -20S C. EXPECT SLOWLY FALLING TEMPS DURING THE DAY SUN. PERSISTENT LES WILL THEN SET UP MON/TUE...MOSTLY FOR W TO WNW WIND FAVORED SNOWBELTS...AS ACRTIC AIR SETTLES OVER THE AREA (850MB TEMPS IN THE MID -20S C). LES WILL THEN CONTINUE THRU THE END OF NEXT WEEK AS ARCTIC AIR WILL DOMINATE THE UPPER LAKES. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 646 AM EST WED DEC 25 2013 LGT SNOW AND FLURRIES CONTINUE INTO EARLY AFTN AS A LOW PRESSURE TROUGH SLOWLY CROSSES THE AREA. EXPECT MVFR CONDITIONS WITH THE SNOW BOTH FM CIGS AND VSBY. AS WINDS TURN TO THE NORTHWEST LATER TODAY INTO TONIGHT IN WAKE OF THE LOW...LAKE EFFECT SNOW SHOWERS WITH IFR CONDITIONS WILL DEVELOP AT IWD AND CMX. POTENTIAL FOR HEAVIER BAND OF SNOW TO PRODUCE LIFR CONDITIONS AT CMX...BUT NOT ENOUGH CONFIDENCE ON EXACT LOCATION TO INCLUDE AT THIS TIME. SOME MORE LGT SNOW OR FLURRIES MAY OCCUR TONIGHT AT SAW AS AN UPPER DISTURBANCE MOVES JUST SOUTH OF THE AREA...THOUGH AFTER THIS SYSTEM MOVES BY CLOUDS MAY TRY TO SCATTER OUT LATE TONIGHT. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 531 AM EST WED DEC 25 2013 GALES EARLY TODAY FOR EASTERN PORTIONS OF LK SUPERIOR AS SOUTH WINDS ARE ENHANCED BY PRESSURE FALLS TO NORTH OF LK SUPERIOR. EXPECT WINDS TO DIMINISH TO LESS THAN 25 KTS LATER AFTN THROUGH TONIGHT. WINDS WILL DIMINISH FURTHER TO 10-20KT ACROSS MOST OF LAKE SUPERIOR THU/THU NIGHT AS A WEAK SFC HIGH PRES RIDGE PASSES. SW WINDS WILL THEN INCREASE TO 15-25KT FRI AHEAD OF THE NEXT APPROACHING COLD FRONT. AS THE FRONT DRIFTS S ACROSS THE AREA...WINDS WILL DIMINISH FRI NIGHT/SAT MORNING. ARCTIC AIR WILL THEN SURGE INTO THE UPPER LAKES LATE SAT THRU EARLY NEXT WEEK. MAY SEE SOME PERIODS OF GALES EARLY NEXT WEEK ALONG WITH THE RETURN OF HVY FREEZING SPRAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...KC SHORT TERM...JLA LONG TERM...ROLFSON AVIATION...JLA MARINE...JLA/ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
648 AM EST WED DEC 25 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 531 AM EST WED DEC 25 2013 PARADE OF SHORTWAVES IN STORE ACROSS UPPER GREAT LAKES FOR NEXT 24 HOURS AS UPR LAKES REMAINS ON PERIFERY OF MEAN TROUGH. LEAD SHORTWAVE AND MOISTURE ADVECTION HAS RESULTED IN WIDESPREAD SNOW WEST TO EAST ACROSS UPR MICHIGAN. LIMITED REPORTS BUT SEEMS MOST SNOW /2-3 INCHES/ OCCURRED IN SCNTRL CWA ON NORTHERN FRINGE OF BETTER DEEP LAYER Q-VECTOR CONVERGENCE. OTHER AREA OF HIGHER SNOWFALL IS DUE TO LAKE ENHANCEMENT OFF LK MICHIGAN OVER FAR EAST CWA...JUST TO EAST OF MANISTIQUE TOWARD NEWBERRY. MQT AND APX RADARS SHOWED MAIN BAND OF LAKE EFFECT AS EARLY AS 06Z WITH ECHOES OVER NORTHERN LK MICHIGAN UP TO 10KFT SUGGESTING HEALTHY BAND OF SNOW. HAVING TO DO A LOT OF INTERPOLATION AND EXTRAPOLATION IN DETERMINING WHAT IS GOING ON IN THSES AREAS USING MDOT WEBCAMS AND FREQUENT CALLS TO THE ISQ AND ERY AWOS /LONG-LINE TRANSMISSION OF MANY AWOS ACROSS THE REGION IS DOWN RIGHT NOW/. WILL HAVE TO WAIT TO GET REPORTS LATER THIS MORNING...BUT AS BEST WE CAN TELL SEEMS THE HEAVIEST AND MOST PERSISTENT SNOW HAS OCCURRED FROM NEAR BLANEY PARK TOWARD MCMILLAN IN SOUTHWEST LUCE COUNTY. JUST WITHIN LAST HOUR...HEAVY SNOW IS PUSHING TOWARD NEWBERRY. GEM-REGIONAL AND HRRR PEGGING THINGS PRETTY WELL. BOTH SHOW THE MAIN CONVERGENCE BAND AND HEAVY SNOW MOVING STEADILY TO THE EAST THIS MORNING...PROBABLY OUT OF ERY BY 15Z IF NOT SOONER. LOWERED SNOW AMOUNTS SLIGHTLY OVER SOUTHERN LUCE...BUT OVERALL WILL KEEP HEADLINES AS IS FOR NOW AS WINDS ALONG LK MICHIGAN SHOWING GUSTS OVER 30 MPH /PROBABLY REPRESENTATIVE WHAT IS OCCURRING WITHIN THE SNOW BAND FARTHER INLAND/ WHICH WOULD BE RESULTING IN BLOWING AND DRIFTING OF THE SNOW. WILL RE-EVALUATE THE HEADLINES TOWARD DAYBREAK TO SEE IF SOME CHANGES ARE NEEDED. ELSEWHERE...EXPECT THE WIDESPREAD SNOW TO TAPER OFF BY DAYBREAK. GUSTY WINDS COULD EASILY BLOW THE FLUFFY SNOW AROUND SO PUT OUT AN SPS MAINLY EMPHASIZING DIFFICULT TRAVEL IN SOME AREAS THIS MORNING. LATER TODAY...ANOTHER SHORTWAVE CURRENTLY SLIDING ACROSS MINNESOTA MAY RESULT IN A CONTINUATION OF SOME LGT SNOW OR FLURRIES FOR MOST OF THE AREA. INTO TONIGHT...EMPHASIS FOR LAKE EFFECT SHIFTS TO THE SNOWBELTS OF WESTERN AND EVENTUALLY FAR NORTHEAST UPR MICHIGAN...MAINLY EAST OF MUNISING AND TO THE NORTH OF NEWBERRY. LAST SHORTWAVE FAIRLY STRONG BUT DIRECT IMPACTS MOSTLY STAY TO THE SOUTH OF UPR MICHIGAN AS WAVE TRACKS FM CNTRL MN ACROSS WI. WAVE MAY ACT TO HOLD TROUGHING IN PLACE OVER SCNTRL LK SUPERIOR RESULTING IN MAINLY WSW WINDS OVER MUCH OF THE LAND AREAS AND NW WINDS OVER LK SUPERIOR. FOR THIS REASON...LEANED TOWARD NCEP WRF-ARW/NMM IDEA OF CONVERGENCE BAND TRYING TO GET GOING OVER THE KEWEENAW TOWARD EASTERN ALGER COUNTY AFTER LATE EVENING. SOUNDINGS FOR TONIGHT SHOW DRYING AND SUBSIDENCE ABOVE H8 BUT BULK OF LAKE EFFECT CONVECTIVE LAYER IS WELL WITHIN THE DGZ RESULTING IN SLR/S SOLIDLY OVER 20:1 AND MAYBE PUSHING TOWARD 30:1. IF CONVERGENCE IS STRONGER...MAY SEE ADVY LEVEL SNOW AMOUNTS FOR PORTIONS OF KEWEENAW AND PERHAPS AS FAR SOUTH AS HIGHER TERRAIN OF NORTHERN ONTONAGON COUNTY...INCLUDING WHITE PINE AND ROCKLAND. SINCE IT WILL BE VERY FLUFFY SNOW AND WINDS/BLSN WILL NOT BE TOO MUCH OF A FACTOR AND SINCE SOME PLACES IN KEWEENAW ARE WELL OVER 100 INCHES ALREADY FOR SEASON...EVENT DOES NOT APPEAR TO SUPPORT THE NEED FOR ADVY AS IT STANDS NOW. DAYSHIFT CAN RE-EVALUATE BUT DID NOT ISSUE AT THIS TIME. HEAVIER LAKE EFFECT WILL ALSO AFFECT THE SNOWBELTS OF THE NORTHEAST CWA WITH MOST SNOW NOT OCCURRING UNTIL WELL AFTER MIDNIGHT ONCE WINDS SHIFT MORE WNW. INLAND FROM THE LAKE EFFECT ISSUES...SKIES MAY TRY TO CLEAR OUT IF THE WINDS ARE MORE WSW THAN WNW. IF THIS OCCURS...TEMPS OVER INLAND WEST AND CNTRL AND MAYBE EVEN EASTERN CWA COULD FALL WELL BELOW ZERO. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 531 AM EST WED DEC 25 2013 WARMING WILL OCCUR LATE THIS WEEK AS FLOW BRIEFLY BECOMES ZONAL ACROSS THE NRN CONUS. HOWEVER...OVER THE NEXT 7 DAYS...THE CURRENT RATHER DISORGANIZED POLAR VORTEX LOCATED WELL N IN NRN CANADA WILL REORGANIZE/EXPAND AND DROP S TO THE VCNTY OF HUDSON BAY. AS A RESULT...ARCTIC AIR WILL AGAIN SPREAD S INTO THE UPPER GREAT LAKES NEXT WEEK...AND THERE MAY BE A COUPLE OF SHOTS OF BITTER COLD AIR. PATTERN DOES NOT LOOK FAVORABLE FOR MUCH IN THE WAY OF WIDESPREAD SYNOPTIC SNOWFALL OVER THE NEXT 7 DAYS. NEXT WEEK...LES WILL BE THE MAIN PCPN CONCERN...MOSTLY FOR SNOWBELTS FAVORED BY W TO NW WINDS. BEGINNING THU...WNW FLOW LES WILL GRADUALLY DIMINISH AS WEAK SFC HIGH PRES RIDGE MOVES FROM THE UPPER MISSISSIPPI VALLEY TOWARD THE UPPER LAKES. DGZ OCCUPIES A GOOD PORTION OF THE CONVECTIVE LAYER... SO MIGHT BE ABLE TO FLUFF UP SEVERAL INCHES OF SNOW ACCUMULATION THU. BEST ACCUMULATIONS SHOULD OCCUR IN FAR NRN ONTONAGON/CNTRL HOUGHTON COUNTIES DUE TO CONVERGENT WRLY FLOW INTO THAT AREA AND ALSO ERN ALGER/NRN LUCE COUNTIES WHERE MODELS DEPICT RATHER STRONG LOW-LEVEL CONVERGENCE. ADVY TYPE HEADLINE MAY BE REQUIRED FOR THE LATTER AREA. WITH PASSAGE OF SFC HIGH PRES RIDGE THU NIGHT...LINGERING LES WILL END AS WINDS SHIFT SW/OFFSHORE. FAVORED THE LOWER SIDE OF GUIDANCE FOR MIN TEMPS WITH AT LEAST A PERIOD OF LIGHT WINDS AND PARTLY CLOUDY SKIES IN MOST AREAS. WAA PATTERN WILL BE IN FULL SWING FRI AS PACIFIC AIR SPREADS OUT ACROSS THE NRN PLAINS IN DEVELOPING ZONAL FLOW. MIGHT BE A LITTLE PCPN ACROSS NRN UPPER MI...BUT BETTER PCPN POTENTIAL WILL BE FARTHER N WHERE SUFFICIENT LOW-LEVEL MOISTENING IS MORE LIKELY. TEMPS WILL REACH THE 20S ACROSS THE BOARD. WARMING WILL CONTINUE SAT AHEAD OF A SHORTWAVE TRACKING FROM BC/PACIFIC NW TO THE NRN PLAINS. MOST LOCATIONS SHOULD TOP OUT AROUND 30F. HOWEVER...A COLD FRONT DRIFTING S ACROSS UPPER MI WILL INFLUENCE MAX TEMPS DEPENDING ON ITS TIMING. UPPER DIVERGENCE ASSOCIATED WITH RIGHT ENTRANCE OF UPPER JET TO THE N AND NE SHOULD SUPPORT A RIBBON OF -SN BEHIND THE SOUTHWARD DRIFTING COLD FRONT. THAT -SN SHOULD BEGIN TO AFFECT NW UPPER MI SAT AFTN. AS COLD FRONT CONTINUES TO DROP S SAT NIGHT/SUN MORNING...EXPECT MOST OF THE FCST AREA TO SEE SOME -SN...AIDED BY RIGHT ENTRANCE UPPER DIVERGENCE. SOME LAKE ENHANCEMENT SEEMS LIKELY FOR MOST IF NOT ALL OF NRN UPPER MI AS WINDS WILL LIKELY SHIFT N FOR A TIME BEHIND COLD FRONT AND POTENTIAL WEAK SFC WAVE THAT WILL ALSO BE TRACKING ALONG FRONT. BEHIND THE COLD FRONT AND WITH THE PASSAGE OF ANOTHER SHORTWAVE ROTATING THRU THE UPPER LAKES AROUND EXPANDING POLAR VORTEX...MUCH COLDER AIR WILL DUMP INTO THE UPPER LAKES SAT NIGHT/SUN. THIS WILL RESULT IN NW FLOW LES TAKING OVER SUN AS 850MB TEMPS PLUMMET INTO THE LOW/MID -20S C. EXPECT SLOWLY FALLING TEMPS DURING THE DAY SUN. PERSISTENT LES WILL THEN SET UP MON/TUE...MOSTLY FOR W TO WNW WIND FAVORED SNOWBELTS...AS ACRTIC AIR SETTLES OVER THE AREA (850MB TEMPS IN THE MID -20S C). LES WILL THEN CONTINUE THRU THE END OF NEXT WEEK AS ARCTIC AIR WILL DOMINATE THE UPPER LAKES. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 646 AM EST WED DEC 25 2013 LGT SNOW AND FLURRIES CONTINUE INTO EARLY AFTN AS A LOW PRESSURE TROUGH SLOWLY CROSSES THE AREA. EXPECT MVFR CONDITIONS WITH THE SNOW BOTH FM CIGS AND VSBY. AS WINDS TURN TO THE NORTHWEST LATER TODAY INTO TONIGHT IN WAKE OF THE LOW...LAKE EFFECT SNOW SHOWERS WITH IFR CONDITIONS WILL DEVELOP AT IWD AND CMX. POTENTIAL FOR HEAVIER BAND OF SNOW TO PRODUCE LIFR CONDITIONS AT CMX...BUT NOT ENOUGH CONFIDENCE ON EXACT LOCATION TO INCLUDE AT THIS TIME. SOME MORE LGT SNOW OR FLURRIES MAY OCCUR TONIGHT AT SAW AS AN UPPER DISTURBANCE MOVES JUST SOUTH OF THE AREA...THOUGH AFTER THIS SYSTEM MOVES BY CLOUDS MAY TRY TO SCATTER OUT LATE TONIGHT. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 531 AM EST WED DEC 25 2013 GALES EARLY TODAY FOR EASTERN PORTIONS OF LK SUPERIOR AS SOUTH WINDS ARE ENHANCED BY PRESSURE FALLS TO NORTH OF LK SUPERIOR. EXPECT WINDS TO DIMINISH TO LESS THAN 25 KTS LATER AFTN THROUGH TONIGHT. WINDS WILL DIMINISH FURTHER TO 10-20KT ACROSS MOST OF LAKE SUPERIOR THU/THU NIGHT AS A WEAK SFC HIGH PRES RIDGE PASSES. SW WINDS WILL THEN INCREASE TO 15-25KT FRI AHEAD OF THE NEXT APPROACHING COLD FRONT. AS THE FRONT DRIFTS S ACROSS THE AREA...WINDS WILL DIMINISH FRI NIGHT/SAT MORNING. ARCTIC AIR WILL THEN SURGE INTO THE UPPER LAKES LATE SAT THRU EARLY NEXT WEEK. MAY SEE SOME PERIODS OF GALES EARLY NEXT WEEK ALONG WITH THE RETURN OF HVY FREEZING SPRAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR MIZ014- 085. WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MIZ007. LAKE SUPERIOR... GALE WARNING UNTIL 7 AM EST THIS MORNING FOR LSZ266. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...ROLFSON AVIATION...JLA MARINE...JLA/ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
533 AM EST WED DEC 25 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 531 AM EST WED DEC 25 2013 PARADE OF SHORTWAVES IN STORE ACROSS UPPER GREAT LAKES FOR NEXT 24 HOURS AS UPR LAKES REMAINS ON PERIFERY OF MEAN TROUGH. LEAD SHORTWAVE AND MOISTURE ADVECTION HAS RESULTED IN WIDESPREAD SNOW WEST TO EAST ACROSS UPR MICHIGAN. LIMITED REPORTS BUT SEEMS MOST SNOW /2-3 INCHES/ OCCURRED IN SCNTRL CWA ON NORTHERN FRINGE OF BETTER DEEP LAYER Q-VECTOR CONVERGENCE. OTHER AREA OF HIGHER SNOWFALL IS DUE TO LAKE ENHANCEMENT OFF LK MICHIGAN OVER FAR EAST CWA...JUST TO EAST OF MANISTIQUE TOWARD NEWBERRY. MQT AND APX RADARS SHOWED MAIN BAND OF LAKE EFFECT AS EARLY AS 06Z WITH ECHOES OVER NORTHERN LK MICHIGAN UP TO 10KFT SUGGESTING HEALTHY BAND OF SNOW. HAVING TO DO A LOT OF INTERPOLATION AND EXTRAPOLATION IN DETERMINING WHAT IS GOING ON IN THSES AREAS USING MDOT WEBCAMS AND FREQUENT CALLS TO THE ISQ AND ERY AWOS /LONG-LINE TRANSMISSION OF MANY AWOS ACROSS THE REGION IS DOWN RIGHT NOW/. WILL HAVE TO WAIT TO GET REPORTS LATER THIS MORNING...BUT AS BEST WE CAN TELL SEEMS THE HEAVIEST AND MOST PERSISTENT SNOW HAS OCCURRED FROM NEAR BLANEY PARK TOWARD MCMILLAN IN SOUTHWEST LUCE COUNTY. JUST WITHIN LAST HOUR...HEAVY SNOW IS PUSHING TOWARD NEWBERRY. GEM-REGIONAL AND HRRR PEGGING THINGS PRETTY WELL. BOTH SHOW THE MAIN CONVERGENCE BAND AND HEAVY SNOW MOVING STEADILY TO THE EAST THIS MORNING...PROBABLY OUT OF ERY BY 15Z IF NOT SOONER. LOWERED SNOW AMOUNTS SLIGHTLY OVER SOUTHERN LUCE...BUT OVERALL WILL KEEP HEADLINES AS IS FOR NOW AS WINDS ALONG LK MICHIGAN SHOWING GUSTS OVER 30 MPH /PROBABLY REPRESENTATIVE WHAT IS OCCURRING WITHIN THE SNOW BAND FARTHER INLAND/ WHICH WOULD BE RESULTING IN BLOWING AND DRIFTING OF THE SNOW. WILL RE-EVALUATE THE HEADLINES TOWARD DAYBREAK TO SEE IF SOME CHANGES ARE NEEDED. ELSEWHERE...EXPECT THE WIDESPREAD SNOW TO TAPER OFF BY DAYBREAK. GUSTY WINDS COULD EASILY BLOW THE FLUFFY SNOW AROUND SO PUT OUT AN SPS MAINLY EMPHASIZING DIFFICULT TRAVEL IN SOME AREAS THIS MORNING. LATER TODAY...ANOTHER SHORTWAVE CURRENTLY SLIDING ACROSS MINNESOTA MAY RESULT IN A CONTINUATION OF SOME LGT SNOW OR FLURRIES FOR MOST OF THE AREA. INTO TONIGHT...EMPHASIS FOR LAKE EFFECT SHIFTS TO THE SNOWBELTS OF WESTERN AND EVENTUALLY FAR NORTHEAST UPR MICHIGAN...MAINLY EAST OF MUNISING AND TO THE NORTH OF NEWBERRY. LAST SHORTWAVE FAIRLY STRONG BUT DIRECT IMPACTS MOSTLY STAY TO THE SOUTH OF UPR MICHIGAN AS WAVE TRACKS FM CNTRL MN ACROSS WI. WAVE MAY ACT TO HOLD TROUGHING IN PLACE OVER SCNTRL LK SUPERIOR RESULTING IN MAINLY WSW WINDS OVER MUCH OF THE LAND AREAS AND NW WINDS OVER LK SUPERIOR. FOR THIS REASON...LEANED TOWARD NCEP WRF-ARW/NMM IDEA OF CONVERGENCE BAND TRYING TO GET GOING OVER THE KEWEENAW TOWARD EASTERN ALGER COUNTY AFTER LATE EVENING. SOUNDINGS FOR TONIGHT SHOW DRYING AND SUBSIDENCE ABOVE H8 BUT BULK OF LAKE EFFECT CONVECTIVE LAYER IS WELL WITHIN THE DGZ RESULTING IN SLR/S SOLIDLY OVER 20:1 AND MAYBE PUSHING TOWARD 30:1. IF CONVERGENCE IS STRONGER...MAY SEE ADVY LEVEL SNOW AMOUNTS FOR PORTIONS OF KEWEENAW AND PERHAPS AS FAR SOUTH AS HIGHER TERRAIN OF NORTHERN ONTONAGON COUNTY...INCLUDING WHITE PINE AND ROCKLAND. SINCE IT WILL BE VERY FLUFFY SNOW AND WINDS/BLSN WILL NOT BE TOO MUCH OF A FACTOR AND SINCE SOME PLACES IN KEWEENAW ARE WELL OVER 100 INCHES ALREADY FOR SEASON...EVENT DOES NOT APPEAR TO SUPPORT THE NEED FOR ADVY AS IT STANDS NOW. DAYSHIFT CAN RE-EVALUATE BUT DID NOT ISSUE AT THIS TIME. HEAVIER LAKE EFFECT WILL ALSO AFFECT THE SNOWBELTS OF THE NORTHEAST CWA WITH MOST SNOW NOT OCCURRING UNTIL WELL AFTER MIDNIGHT ONCE WINDS SHIFT MORE WNW. INLAND FROM THE LAKE EFFECT ISSUES...SKIES MAY TRY TO CLEAR OUT IF THE WINDS ARE MORE WSW THAN WNW. IF THIS OCCURS...TEMPS OVER INLAND WEST AND CNTRL AND MAYBE EVEN EASTERN CWA COULD FALL WELL BELOW ZERO. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 531 AM EST WED DEC 25 2013 WARMING WILL OCCUR LATE THIS WEEK AS FLOW BRIEFLY BECOMES ZONAL ACROSS THE NRN CONUS. HOWEVER...OVER THE NEXT 7 DAYS...THE CURRENT RATHER DISORGANIZED POLAR VORTEX LOCATED WELL N IN NRN CANADA WILL REORGANIZE/EXPAND AND DROP S TO THE VCNTY OF HUDSON BAY. AS A RESULT...ARCTIC AIR WILL AGAIN SPREAD S INTO THE UPPER GREAT LAKES NEXT WEEK...AND THERE MAY BE A COUPLE OF SHOTS OF BITTER COLD AIR. PATTERN DOES NOT LOOK FAVORABLE FOR MUCH IN THE WAY OF WIDESPREAD SYNOPTIC SNOWFALL OVER THE NEXT 7 DAYS. NEXT WEEK...LES WILL BE THE MAIN PCPN CONCERN...MOSTLY FOR SNOWBELTS FAVORED BY W TO NW WINDS. BEGINNING THU...WNW FLOW LES WILL GRADUALLY DIMINISH AS WEAK SFC HIGH PRES RIDGE MOVES FROM THE UPPER MISSISSIPPI VALLEY TOWARD THE UPPER LAKES. DGZ OCCUPIES A GOOD PORTION OF THE CONVECTIVE LAYER... SO MIGHT BE ABLE TO FLUFF UP SEVERAL INCHES OF SNOW ACCUMULATION THU. BEST ACCUMULATIONS SHOULD OCCUR IN FAR NRN ONTONAGON/CNTRL HOUGHTON COUNTIES DUE TO CONVERGENT WRLY FLOW INTO THAT AREA AND ALSO ERN ALGER/NRN LUCE COUNTIES WHERE MODELS DEPICT RATHER STRONG LOW-LEVEL CONVERGENCE. ADVY TYPE HEADLINE MAY BE REQUIRED FOR THE LATTER AREA. WITH PASSAGE OF SFC HIGH PRES RIDGE THU NIGHT...LINGERING LES WILL END AS WINDS SHIFT SW/OFFSHORE. FAVORED THE LOWER SIDE OF GUIDANCE FOR MIN TEMPS WITH AT LEAST A PERIOD OF LIGHT WINDS AND PARTLY CLOUDY SKIES IN MOST AREAS. WAA PATTERN WILL BE IN FULL SWING FRI AS PACIFIC AIR SPREADS OUT ACROSS THE NRN PLAINS IN DEVELOPING ZONAL FLOW. MIGHT BE A LITTLE PCPN ACROSS NRN UPPER MI...BUT BETTER PCPN POTENTIAL WILL BE FARTHER N WHERE SUFFICIENT LOW-LEVEL MOISTENING IS MORE LIKELY. TEMPS WILL REACH THE 20S ACROSS THE BOARD. WARMING WILL CONTINUE SAT AHEAD OF A SHORTWAVE TRACKING FROM BC/PACIFIC NW TO THE NRN PLAINS. MOST LOCATIONS SHOULD TOP OUT AROUND 30F. HOWEVER...A COLD FRONT DRIFTING S ACROSS UPPER MI WILL INFLUENCE MAX TEMPS DEPENDING ON ITS TIMING. UPPER DIVERGENCE ASSOCIATED WITH RIGHT ENTRANCE OF UPPER JET TO THE N AND NE SHOULD SUPPORT A RIBBON OF -SN BEHIND THE SOUTHWARD DRIFTING COLD FRONT. THAT -SN SHOULD BEGIN TO AFFECT NW UPPER MI SAT AFTN. AS COLD FRONT CONTINUES TO DROP S SAT NIGHT/SUN MORNING...EXPECT MOST OF THE FCST AREA TO SEE SOME -SN...AIDED BY RIGHT ENTRANCE UPPER DIVERGENCE. SOME LAKE ENHANCEMENT SEEMS LIKELY FOR MOST IF NOT ALL OF NRN UPPER MI AS WINDS WILL LIKELY SHIFT N FOR A TIME BEHIND COLD FRONT AND POTENTIAL WEAK SFC WAVE THAT WILL ALSO BE TRACKING ALONG FRONT. BEHIND THE COLD FRONT AND WITH THE PASSAGE OF ANOTHER SHORTWAVE ROTATING THRU THE UPPER LAKES AROUND EXPANDING POLAR VORTEX...MUCH COLDER AIR WILL DUMP INTO THE UPPER LAKES SAT NIGHT/SUN. THIS WILL RESULT IN NW FLOW LES TAKING OVER SUN AS 850MB TEMPS PLUMMET INTO THE LOW/MID -20S C. EXPECT SLOWLY FALLING TEMPS DURING THE DAY SUN. PERSISTENT LES WILL THEN SET UP MON/TUE...MOSTLY FOR W TO WNW WIND FAVORED SNOWBELTS...AS ACRTIC AIR SETTLES OVER THE AREA (850MB TEMPS IN THE MID -20S C). LES WILL THEN CONTINUE THRU THE END OF NEXT WEEK AS ARCTIC AIR WILL DOMINATE THE UPPER LAKES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1200 AM EST WED DEC 25 2013 IFR CONDITIONS WITH LIGHT SNOW WILL CONTINUE EARLY THIS FORECAST PERIOD AS A TROF MOVES ACROSS THE AREA. AS THE SN DIMINISHES W-E BY SUNRISE ON WED...MVFR SC CIGS WL LINGER. AS THE WEAKER FLOW VEERS TOWARD THE W LATER ON WED MRNG...MORE SHSN/IFR VSBYS MAY IMPACT CMX BY EARLY WED EVENING. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 531 AM EST WED DEC 25 2013 GALES EARLY TODAY FOR EASTERN PORTIONS OF LK SUPERIOR AS SOUTH WINDS ARE ENHANCED BY PRESSURE FALLS TO NORTH OF LK SUPERIOR. EXPECT WINDS TO DIMINISH TO LESS THAN 25 KTS LATER AFTN THROUGH TONIGHT. WINDS WILL DIMINISH FURTHER TO 10-20KT ACROSS MOST OF LAKE SUPERIOR THU/THU NIGHT AS A WEAK SFC HIGH PRES RIDGE PASSES. SW WINDS WILL THEN INCREASE TO 15-25KT FRI AHEAD OF THE NEXT APPROACHING COLD FRONT. AS THE FRONT DRIFTS S ACROSS THE AREA...WINDS WILL DIMINISH FRI NIGHT/SAT MORNING. ARCTIC AIR WILL THEN SURGE INTO THE UPPER LAKES LATE SAT THRU EARLY NEXT WEEK. MAY SEE SOME PERIODS OF GALES EARLY NEXT WEEK ALONG WITH THE RETURN OF HVY FREEZING SPRAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR MIZ014- 085. WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MIZ007. LAKE SUPERIOR... GALE WARNING UNTIL 7 AM EST THIS MORNING FOR LSZ266. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...ROLFSON AVIATION...07 MARINE...JLA/ROLFSON
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
608 AM CST WED DEC 25 2013 .UPDATE... 12Z AVIATION DISCUSSION ADDED BELOW. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 337 AM CST WED DEC 25 2013 TROUGHING AND CYCLONIC FLOW WILL DOMINATE THE SHORT TERM...WHICH MEANS LOTS OF CLOUDS AND BOUTS OF LIGHT SNOW WILL DOMINATE THE NEXT 24 HOURS. LOOKING AT WATER VAPOR IMAGERY OVERLAID WITH RAP H5 VORTICITY YOU CAN SEE A COUPLE OF WAVES UPSTREAM IN THE NW FLOW THAT WILL IMPACT US. THE FIRST IS CURRENTLY OVER ERN NODAK AND ALREADY HAS SNOW MOVING ACROSS ERN SODAK AND NW MN AND WILL BE ARRIVING IN THE MPX CWA SHORTLY. THE SECOND WAVE IS UP OVER NRN SASKATCHEWAN AND WILL BE WORKING ACROSS MN THIS AFTERNOON. THESE UPPER WAVES WILL BE WORKING WITH AN ELEVATED WARM FRONT IN THE H85-H7 LAYER TO THROW SEVERAL BOUTS OF LIGHT SNOW OUR DIRECTION THROUGH THE PERIOD. THE BEST BURST WILL BE THE INITIAL ONE THIS MORNING. THE HEAVIEST SNOW HAS BEEN ALONG THAT ELEVATED WARM FRONT OVER ERN SODAK OVERNIGHT AND FOLLOWED THE HRRR FOR BRINGING THIS SNOW DOWN THE MN RIVER THIS MORNING. HAVE ENOUGH QPF OUT OF IT TO GET 0.5 TO 1 INCH SNOW AMOUNTS FROM WC MN DOWN THE MN RIVER INTO SE MN. FOR THE REST OF THE PERIOD...THE PATTERN IN PLACE LEADS TO LOW CONFIDENCE ON WHEN/WHERE THESE LITTLE BURSTS OF SNOW WILL COME DOWN...SO THERE ARE LOTS OF SMALL POPS THROUGH 9Z TONIGHT...WHICH IS WHEN THE SREF AND HIRES MODELS FINALLY SHOW SNOW CHANCES EVACUATING THE MPX CWA...FOR A SHORT TIME ANYWAYS. TEMPERATURES WILL BE TRICKY THIS PERIOD AS WELL THANKS TO A SFC WARM FRONT THAT AT 3AM WAS NEAR A ROSEAU/LONG PRAIRIE/TWIN CITIES/ALBERT LEA LINE. TEMPERATURES EAST OF THIS BOUNDARY HAVE REMAINED IN THE SINGLE DIGITS...WITH TEMPERATURES SLOWLY RISING INTO THE TEENS AND EVEN LOWER 20S BY THE TIME YOU GET TO THE MN/SD BORDER. THE COLD FRONT WAS ALIGNED FROM A WEAK SFC LOW NEAR GRAND FORKS BACK NW INTO CENTRAL SASKATCHEWAN. THE WARM SECTOR ACROSS THE DAKOTAS HAS BEEN QUITE IMPRESSIVE THIS MORNING...WITH SEVERAL LOCATIONS ACROSS THE CENTRAL DAKOTAS WARMING TO BETWEEN 32 AND 34 DEGREES /ABOUT 35 DEGREES WARMER THAN THIS TIME 24 HOURS AGO!/. THE QUESTION FOR TODAY...IS HOW MUCH OF THIS WARM SECTOR CAN WE GET INTO THE MPX CWA. THE CORE OF THE WARMEST AIR LOOKS TO DROP SOUTHWEST OF THE MPX CWA...BUT WE SHOULD STILL SEE TEMPS RISE INTO THE UPPER 20S ACROSS WRN MN THIS MORNING...BEFORE THE COLD FRONT ARRIVES THIS AFTERNOON TO START SENDING TEMPERATURES THE OTHER DIRECTION. FOR TONIGHT THE TWO VARIABLES TO WATCH ARE WHAT HAPPENS WITH CLOUD COVER AND WHERE DOES THAT COLD FRONT END UP. AS FOR THE FRONT...MOST MODELS SHOW THE FRONT BECOMING STATIONARY ACROSS SW MN...WITH ANOTHER PUNCH OF ARCTIC AIR SLIDING DOWN ACROSS AREAS MAINLY NORTH OF I-94. THIS WILL KEEP TEMPERATURES TONIGHT IN THE MN RIVER VALLEY ON SOUTH UP IN THE TEENS...BUT BACK NORTH OF I-94...IF SKIES CAN STAY SUFFICIENTLY CLEAR...WE COULD SEE MORE WIDESPREAD DOUBLE DIGIT LOWS BELOW ZERO. IT/S NOT OUT OF THE REAL OF POSSIBILITY TO SEE A NEARLY A NEARLY 30 DEGREE SPREAD IN LOWS TONIGHT ACROSS THE MPX CWA...WITH LOWS AROUND 15 ABOVE OUT IN WRN MN AND AROUND 15 BELOW ALONG THE US-8 CORRIDOR IN WRN WI. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 337 AM CST WED DEC 25 2013 THE FORECAST WARM UP FOR THE LATER HALF OF THE WEEK STILL LOOKS TO BE ON SCHEDULE. SHOULD SEE MODERATING TEMPERATURES INTO SATURDAY WITH ANOTHER WAFT OF PACIFIC AIR MOVING THROUGH...AHEAD OF NEXT ARCTIC COLD FRONT. MODELS TREND ANOTHER SHOT OF SNOW ASSOCIATED WITH THE INITIAL PACIFIC AIR INTRUSION ON THURSDAY. AT THE MOMENT...HAVE INCLUDED A SMALL LIKELY POP AREA OVER THE NORTHEAST CWA. SIGNIFICANT MOISTURE APPEARS TO BE LACKING AND MOST MODELS HAVING TROUBLE SATURATING AS THE PRECIPITATION BAND MOVES FARTHER EAST. ANY SNOWFALL SHOULD REMAIN LIGHT FOR THIS SYSTEM. DO EXPECT SOME LOWER 30S AT LEAST AHEAD OF THE ARCTIC BOUNDARY AS THAT ARRIVES SATURDAY AFTERNOON. WITH STEEP LOW LEVEL LAPSE RATES...STRONG WIND GUSTS EXPECTED TO MATERIALIZE. 35 KT WIND GUSTS LOOK LIKELY AS THE SYSTEM MOVES THROUGH. THE BETTER CHANCE OF SNOW SHOWERS SHOULD RIDE FARTHER EAST...BUT IF THEY DO COINCIDE WITH THE STRONGEST WINDS...COULD SEE NEAR BLIZZARD CONDITIONS DEVELOP OVER THE SOUTHWEST/MINNESOTA RIVER VALLEY REGION SATURDAY AFTERNOON/EVENING. HAVE CONTINUED TO INCLUDE SOME BLOWING SNOW OVER THE REGION FOR THIS PERIOD...INTO SUNDAY. THE NEXT SURGE OF ARCTIC AIR DROPS OVER THE REGION SUNDAY AND LINGERS THROUGH MUCH OF THE COMING WEEK. NORTHWEST FLOW PATTERN WILL LEAVE THE REGION IN THE FAVORABLE AREA FOR MORE LIGHT/FLUFFY SNOW EVENTS. MONDAY NIGHT INTO TUESDAY NIGHT LOOKS LIKE THE NEXT BEST CHANCE OF SOME LIGHT SNOW. HAVE LOW POPS FOR NOW. WILL HOLD OFF ON HIGHER POPS FOR NOW...TO GET BETTER TIMING AS WE GET CLOSER TO THE EVENT. WIND CHILLS WILL ONCE AGAIN BECOME AN ISSUE AS THE COLD AIR ARRIVES AS WELL. THE 00Z ECMWF SHOWS LITTLE MODERATION IN TEMPERATURES IN THE LONGER TERM...WHICH WOULD TAKE US INTO THE FIRST WEEK OF THE NEW YEAR. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 540 AM CST WED DEC 25 2013 THE COMBINATION OF CYCLONIC FLOW AND A WARM FRONT LAYING OUT ACROSS THE AREA THIS TAF PERIOD WILL RESULT IN PLENTY OF CLOUD COVER WITH NUMEROUS BOUTS OF LIGHT SNOW. MOST CONFIDENCE ON THE SNOW EXISTS WITH BURST CURRENTLY WORKING ACROSS THE AREA. HAVE CONTINUED TO FOLLOW THE HRRR TO TREND THIS SNOW THROUGH THE TERMINALS. EXPECT IFR VSBY SNOW TO REMAIN SOUTH OF ALL TERMINALS BUT RWF...WITH THE REST JUST DEALING WITH 2 TO 4 HOURS OF INTERMITTENT MVFR SNOWS THIS MORNING. AFTER THAT...SREF PROBS AND HIGH-RES MODELS SHOW A RATHER CHAOTIC SNOW PICTURE PLAYING OUT THROUGH TONIGHT. GIVEN THE LOW CONFIDENCE ON WHEN/WHERE FUTURE BANDS OF SNOW WILL EXIST...LEFT ANY SNOW MENTION BEYOND THIS MORNING OUT...THOUGH IN ALL LIKELIHOOD MORE MVFR TYPE SNOWS WILL BE SEEN FROM TIME TO TIME BEYOND THIS MORNING. CIGS WILL MOSTLY STAY MVFR THROUGH THE MORNING...BUT AS A COLD FRONT SLOWLY SLIDES SOUTH THROUGH THE AREA THIS AFTERNOON/EVENING WILL LIKELY SEE SOME BREAKS IN THE CLOUDS...THOUGH CLOUD COVER WILL DOMINATE THE SCENE. LOW CONFIDENCE BEYOND THIS AFTERNOON WITH CIG HEIGHTS...SO WENT CONSERVATIVE WITH CIGS BECOMING VFR THIS EVENING...THOUGH WE WILL PROBABLY SEE MVFR OR LOWER CIGS AT TIMES RIGHT THROUGH THE END OF THE PERIOD. WINDS WILL BE STRONGEST THIS MORNING/EARLY AFTERNOON AHEAD OF THE COLD FRONT OVER SW MN...WILL LIKELY SEE SOME BLSN...THOUGH HARD TO SAY IF IT WILL LEAD TO VIS RESTRICTIONS AT RWF...BUT LEFT THAT IDEA IN FROM THE PREVIOUS TAF. KMSP...BASED ON RADAR...LOOKING LIKE HEAVIEST SNOW WILL GO SOUTH AND NORTH OF THE FIELD...THOUGH A PERIOD OF MVFR VSBYS STILL LOOKS LIKELY THIS MORNING. WILL LIKELY BE MORE SNOW AFTER THIS MORNING...BUT CONFIDENCE TOO LOW ON WHEN ADDITIONAL SNOW SHOWERS WILL OCCUR TO INCLUDE IN THE TAF AT THIS TIME. BASED ON UPSTREAM OBS...CIGS CURRENTLY ABOVE 017 LOOK TO BE SHORT LIVED...WITH CIGS MAINLY 012-015 NW OF MSP. CONFIDENCE IN CIG FORECAST THIS AFTERNOON ON IS LOW. WINDS LOOK TO GO NORTH OF 240 BETWEEN 16Z AND 18Z...SO WILL EVENTUALLY HAVE TO GET EVERYTHING OVER TO THE 30S THIS AFTERNOON. /OUTLOOK FOR KMSP/ THU...CHANCE MVFR CIGS/VSBYS IN -SN. WINDS S AT 5 KTS. FRI...VFR. WINDS SW 5-10 KTS. SAT...VFR. CHC MVFR/-SN LATE. WINDS SW 5-10 KTS BCMG NW 20G30KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM...DWE AVIATION...MPG
AREA FORECAST DISCUSSION
NWS HASTINGS NE
542 AM CST WED DEC 25 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 407 AM CST WED DEC 25 2013 WITH ESSENTIALLY ZERO RISK OF PRECIP THROUGH THE NEXT 24 HOURS...THE MAIN FORECAST ISSUES INVOLVE TEMPS/SKY COVER/AND HOW BREEZY IT WILL GET TODAY. TEMP-WISE...WHAT WOULD OTHERWISE BE A FAIRLY STRAIGHTFORWARD SITUATION IS COMPLICATED SOMEWHAT BY SOME MODELS/GUIDANCE STRUGGLING WITH THE INITIALIZATION OF EXISTING SNOW COVER. STARTING OFF EARLY THIS CHRISTMAS MORNING...ALL IS QUIET...AS THE LATEST 11-3.9 MICRON SATELLITE IMAGERY INDICATES ESSENTIALLY CLEAR SKIES CWA-WIDE...IN THE WAKE OF LOW STRATUS THAT HAS PUSHED EAST OF THE AREA...AND A BATCH OF MID LEVEL CLOUDS THAT HAS PUSHED SOUTH OF THE CWA. WATER VAPOR SATELLITE IMAGERY AND SHORT TERM MODEL DATA INDICATE A BROAD MID-UPPER TROUGH CENTERED OVER THE CENTRAL CONUS NORTHWARD INTO SOUTH CENTRAL CANADA...WHILE FARTHER WEST...A LARGE-SCALE RIDGE IS CENTERED OFF THE CA COAST IN THE PACIFIC. WITHIN THE LARGE SCALE TROUGH OVER THE LOCAL AREA...THERE ARE FEW SMALLER SCALE SHORTWAVE TROUGHS OF INTEREST...ONE OF WHICH IS CURRENTLY ORIENTED SOUTHWEST-NORTHEAST FROM SOUTHWEST KS- NORTHERN MO...AND IS EXITING THE SOUTHEAST CWA AT THIS TIME. MEANWHILE...ANOTHER CLIPPER-TYPE NORTHWEST-FLOW SHORTWAVE IS IN THE PROCESS OF DROPPING SOUTHWARD INTO THE DAKOTAS/MN...WITHIN THE EXIT REGION OF A STOUT 120+KT NORTHERLY JET STREAK EVIDENT AT 300 MILLIBARS THAT IS CURRENTLY POKING SOUTHWARD INTO MT OUT OF SASKATCHEWAN. AT THE SURFACE...09Z OBJECTIVE ANALYSIS AND AUTOMATED OBS REVEAL A FAIRLY UNIFORM FIELD OF WESTERLY BREEZES GENERALLY 5-10 MPH ACROSS THE CWA...DRIVEN WITHIN A FAIRLY WEAK PRESSURE GRADIENT BETWEEN A 1029MB HIGH CENTERED OVER THE NEB/CO BORDER AREA AND EXTENDING SOUTHEAST ACROSS KS...AND A 1015MB LOW CENTERED OVER NORTHWEST MN ASSOCIATED WITH THE AFOREMENTIONED CLIPPER. TEMP-WISE EARLY THIS MORNING...AS WESTERLY BREEZES HAVE BECOME MORE ESTABLISHED MOST PLACES HAVE LARGELY LEVELED OFF THE NOCTURNAL DROP OR EVEN RISEN SOMEWHAT FROM VALUES EARLIER IN THE NIGHT...BUT GIVEN THE CLEAR SKIES...SOME LOCALIZED DROPS ARE STILL LIKELY BEFORE THE NIGHT IS THROUGH. ACTUAL LOWS FOR THE NIGHT ALREADY HAVE BEEN...OR WILL EVENTUALLY BE...SOMEWHERE BETWEEN 15-21 ACROSS MOST OF THE CWA. FOR THE DAYTIME HOURS TODAY...THE MAIN STORY IN THE MID-UPPER LEVELS INVOLVES THE SOUTH-SOUTHEAST PROGRESSION OF THE AFOREMENTIONED CLIPPER SYSTEM...WHICH WILL MAINLY TAKE AIM ON THE MN/IA REGION AS THE MAIN VORTICITY MAXIMUM AT 500MB ENDS UP OVER NORTHERN MN BY 00Z/6PM TODAY. GIVEN THE TRACK OF THIS SYSTEM AND ITS FORCING FIELDS...ANY LIGHT PRECIP TODAY SHOULD MAINLY FOCUS ALONG A TRACK FROM EASTERN SD ACROSS SOUTHERN MN/NORTHERN IA...AND MAYBE AS FAR SOUTHWEST AS EXTREME NORTHEAST NEB. ALONG THESE SAME LINES...THE VAST MAJORITY OF THE CWA SHOULD SEE NOTHING MORE THAN LIMITED MID-HIGH CLOUD COVER TODAY...WITH SKIES AVERAGING OUT TO NO WORSE THAN MOSTLY SUNNY. THAT BEING SAID...MODELS SUCH AS THE 06Z NAM AND TO A GREATER EXTENT THE 08Z RAP 13 SHOW THAT THE SOUTHWEST EDGES OF WHAT COULD BE A FAIRLY SOLID BATCH OF LOWER STRATUS COULD COME VERY CLOSE TO INFILTRATING A FEW COUNTIES IN THE FAR NORTHEAST CWA SUCH AS NANCE/POLK...ALTHOUGH THE VAST MAJORITY OF THIS CLOUD MASS SHOULD PASS 50+ MILES EAST/NORTHEAST OF THE CWA. ALTHOUGH THE OFFICIAL FORECAST RUNS WITH THE ASSUMPTION THAT SKIES BECOME NO WORSE THAN PARTLY CLOUDY FOR A FEW HOURS IN THESE FAR NORTHEAST AREAS...THIS WILL BARE WATCHING AS THE RAP 900/850MB RELATIVE HUMIDITY FIELDS ARE CURRENTLY HANDLING UPSTREAM LOWER CLOUDS OVER NORTH CENTRAL/EASTERN SD PRETTY WELL. TURNING TO THE SURFACE SITUATION...THE MAIN FEATURE TODAY WILL BE SEVERAL HOURS OF INCREASED NORTHWEST BREEZES...AS ENHANCED LOWER LEVEL WINDS MIX DOWN TO THE SURFACE AS MIXING HEIGHTS INCREASE TO AROUND 875MB. THE PRIMARY PERIOD OF ENHANCED NORTHWEST BREEZES WILL FOCUS BETWEEN 15Z/9AM TO 22Z/4PM...WITH SUSTAINED SPEEDS 15-20 MPH AND GUSTS AT LEAST 20-25 MPH...AND GENERALLY STRONGEST ACROSS THE NORTHEAST 1/2 OF THE CWA. ALTHOUGH THIS NORTHWESTERLY WIND TECHNICALLY RESULTS IN AT LEAST WEAK COLD AIR ADVECTION ABOVE THE SURFACE EVIDENT AT 850MB...THE COMBINATION OF SUNSHINE AND DECENT MIXING SHOULD RESULT IN A CONSIDERABLY MILDER DAY...ESPECIALLY IN THOSE CENTRAL/EASTERN COUNTIES THAT REMAINED QUITE CLOUDY TUESDAY. AS HAS BEEN TYPICAL LATELY...TEMPERATURE FIELDS IN MODELS SUCH AS THE NAM12 AND ASSOCIATED GUIDANCE ARE HEAVILY CONTAMINATED BY OVER-ZEALOUS SNOW COVER INITIALIZATION. FORTUNATELY...THE HOURLY TEMP FIELD OF THE RAP13 LOOKED QUITE REASONABLE AND UNCONTAMINATED...AND THUS WAS FOLLOWED VERY CLOSELY TODAY. THIS RESULTED IN SIMILAR HIGH TEMPS TO PREVIOUS FORECAST...BUT 1-2 DEGREES WARMER IN MANY CENTRAL/SOUTHERN AREAS. THE NET RESULT IS A RANGE FROM UPPER 30S NORTH...LOW 40S CENTRAL AND MID 40S SOUTH...ALTHOUGH A RESPECTABLE 1-3 INCHES OF SNOW COVER CENTERED OVER MUCH OF FURNAS/GOSPER/HARLAN COUNTIES WILL LIKELY KEEP THOSE AREAS A BIT COOLER THAN BORDERING AREAS...GENERALLY UPPER 30S. TURNING TO THIS EVENING/TONIGHT...A RATHER QUIET AND PRECIP-FREE FORECAST CONTINUES. IN THE MID/UPPER LEVELS...MODEST HEIGHT RISES WILL BE EVIDENT AT 500MB OVER THE LOCAL AREAS...IN THE WAKE OF THE FAIRLY VIGOROUS CLIPPER SYSTEM DEPARTING EASTWARD INTO THE LOWER GREAT LEGION. MEANWHILE THOUGH...A WEAKER/MORE SUBTLE NORTHWEST- FLOW DISTURBANCE WILL GRADUALLY APPROACH THE CENTRAL PLAINS FROM THE NORTHERN ROCKIES...REACHING THE SD/NORTHWEST NEB AREA BY SUNRISE THURSDAY. LOCALLY...THE ONLY EFFECT OF THIS INCOMING WEAK WAVE WILL BE A MODEST INCREASE IN MAINLY HIGH LEVEL CLOUDS ESPECIALLY OVER NORTHERN ZONES...BUT EVEN SO...OVERNIGHT SKIES ARE FORECAST TO AVERAGE NO WORSE THAN MOSTLY CLEAR ACROSS THE MAJORITY OF THE CWA. AT THE SURFACE...WEAK PRESSURE FALLS CENTERED OVER THE DAKOTAS WILL ALLOW LOCAL BREEZES TO TRANSITION FROM NORTHWESTERLY THIS AFTERNOON TO A WEST-SOUTHWEST DIRECTION AT GENERALLY 5-10 MPH THROUGH THE OVERNIGHT HOURS. ALTHOUGH THESE WESTERLY BREEZES WILL INDUCE MODEST WARM AIR ADVECTION ALOFT EVIDENT AT 850MB...THE FAIRLY LIGHT SPEEDS WILL PROBABLY NOT BE ENOUGH TO OFFSET A DECENT TEMP DROP UNDER THE MOSTLY CLEAR SKIES. THUS TOOK A MIDDLE-GROUND APPROACH ON LOW TEMPS...MAKING VERY LITTLE CHANGE FROM PREVIOUS FORECAST VIA A MULTI-MODEL BLEND...RESULTING IN A FAIRLY UNIFORM LOW TEMPERATURE FIELD OF 16-20 ACROSS THE CWA. THIS IS GENERALLY 2-4 DEGREES MILDER THAN A BLEND OF 00Z MET/MAV GUIDANCE WHICH APPEARS TO BE A BIT TOO COLD...BUT IS NOT AS WARM AS RAW 2M TEMPS PRESENTED BY MODELS SUCH AS THE GFS/ECMWF. AS IS TYPICAL IN THESE OVERNIGHT WESTERLY WIND REGIMES THOUGH...THERE WILL LIKELY BE SCATTERED NON-DIURNAL TEMP TENDENCIES ACROSS PARTS OF THE AREA. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 407 AM CST WED DEC 25 2013 THURSDAY THROUGH NEW YEARS EVE DAY/TUESDAY. THE LATTER PART OF THE WEEK INTO THE FIRST PART OF THE WEEKEND ARE STILL SHAPING UP TO BE THE NICEST/WARMEST DAYS OF THE EXTENDED TIME FRAME. A NORTHWEST FLOW PATTERN WILL BE IN PLACE ACROSS OUR REGION WHILE THE UPPER TROUGH AND COLD AIR THROUGH THE OHIO VALLEY REGION LIFTS OUT ACROSS THE NORTHEAST CONUS. A WARMER AIRMASS WILL SETTLE IN FOR A FEW DAYS AND A DRY DOWNSLOPE WESTERLY WIND COMPONENT WILL AID IN THE TEMP WARMUP FOR OUR AREA. HIGH ON THURSDAY SHOULD AVERAGE IN THE LOW/MID 40S...WITH EVEN WARMER 50S EXPECTED FOR FRIDAY. TEMPERATURES ON SATURDAY WILL BE DEPENDENT UPON THE TIMING OF A STRONG COLD FRONTAL PASSAGE WHICH IS PROGGED TO CROSS OUR CWA DURING THE AFTN/EVENING. IF TIMING TRENDS FASTER...TEMPS WILL NOT BE AS WARM AS CURRENT FORECAST ESPECIALLY ACROSS OUR NORTHERN ZONES AND THERMAL GRADIENT WILL NEED TO BE TIGHTENED. THE 6HR PRESSURE RISES BEHIND FRONT AVERAGE 11MB AND EXPECT A PERIOD OF STRONG/GUSTY NORTH WINDS FOLLOWING FROPA AND HAVE RAMPED UP WIND SPEEDS HIGHER THAN WHAT INIT PROVIDED. MODELS ALSO SUGGEST LOW CLOUDS MOVING IN BEHIND BOUNDARY AND AS PREVIOUS DISCUSSION MENTIONED...COULD SEE SOME FLURRIES SATURDAY EVENING/NIGHT IN PRESENCE OF FRONTOGENESIS...AND IS SOMETHING TO MONITOR. A 1035MB SURFACE HIGH BUILDS SOUTH ONTO THE PLAINS SUNDAY BEHIND THE COLD FRONT AND TEMPERATURES WILL DROP BACK BELOW SEASONAL NORMALS FOR A COUPLE OF DAYS. THE AIRMASS LOOKS TO MODERATE SOME FROM LATE MONDAY INTO TUESDAY/NEW YEARS EVE DAY AND TEMPS NEAR NORMAL APPEAR REASONABLE FOR NOW. THIS BEING SAID...A COLD AIRMASS IS NOT THAT FAR AWAY AS A TROUGH DEEPENS OVER THE HUDSON BAY. && .AVIATION...(FOR THE 12Z KGRI TAF THROUGH 12Z THURSDAY MORNING) ISSUED AT 542 AM CST WED DEC 25 2013 CONFIDENCE REMAINS HIGH IN VFR CEILING/VISIBILITY THROUGHOUT THE PERIOD...WITH ONLY LIMITED AMOUNTS OF PASSING MID/HIGH CLOUD COVER...AND ANY DAYTIME BATCHES OF LOWER MVFR HEIGHT STRATUS LIKELY TO REMAIN AT LEAST 60-80 MILES NORTHEAST OF KGRI. AS FOR SURFACE WINDS...MADE VERY LITTLE CHANGE TO PREVIOUS FORECAST...WITH BREEZES BOTH RIGHT AWAY EARLY THIS MORNING AND AGAIN THIS EVENING/TONIGHT AVERAGING FROM A WESTERLY DIRECTION NEAR/UNDER 10KT. HOWEVER...FOR SEVERAL HOURS TODAY ESPECIALLY BETWEEN 17Z-20Z...NORTHWEST WINDS WILL INCREASE TO SUSTAINED SPEEDS NEAR 16KT WITH GUST POTENTIAL TO AROUND 23KT...BEFORE SUBSIDING LATE THIS AFTERNOON. PRIOR TO THE ONSET OF THE ENHANCED BREEZES AT THE SURFACE...THERE WILL LIKELY BE AT LEAST A FEW HOURS OF MODEST LOW LEVEL WIND SHEAR AS WINDS ACCELERATE INTO THE 40-45KT RANGE FROM THE NORTHWEST WITHIN THE LOWEST 1500 FT AGL. GIVEN THAT THE WIND VECTOR MAGNITUDE DIFFERENCE BETWEEN THE SURFACE AND THIS LEVEL IS FORECAST TO BE AT LEAST 35KT...INSERTED A FORMAL MENTION OF LLWS FROM 14Z-16Z THIS MORNING. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...PFANNKUCH LONG TERM...FAY AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
407 AM CST WED DEC 25 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 407 AM CST WED DEC 25 2013 WITH ESSENTIALLY ZERO RISK OF PRECIP THROUGH THE NEXT 24 HOURS...THE MAIN FORECAST ISSUES INVOLVE TEMPS/SKY COVER/AND HOW BREEZY IT WILL GET TODAY. TEMP-WISE...WHAT WOULD OTHERWISE BE A FAIRLY STRAIGHTFORWARD SITUATION IS COMPLICATED SOMEWHAT BY SOME MODELS/GUIDANCE STRUGGLING WITH THE INITIALIZATION OF EXISTING SNOW COVER. STARTING OFF EARLY THIS CHRISTMAS MORNING...ALL IS QUIET...AS THE LATEST 11-3.9 MICRON SATELLITE IMAGERY INDICATES ESSENTIALLY CLEAR SKIES CWA-WIDE...IN THE WAKE OF LOW STRATUS THAT HAS PUSHED EAST OF THE AREA...AND A BATCH OF MID LEVEL CLOUDS THAT HAS PUSHED SOUTH OF THE CWA. WATER VAPOR SATELLITE IMAGERY AND SHORT TERM MODEL DATA INDICATE A BROAD MID-UPPER TROUGH CENTERED OVER THE CENTRAL CONUS NORTHWARD INTO SOUTH CENTRAL CANADA...WHILE FARTHER WEST...A LARGE-SCALE RIDGE IS CENTERED OFF THE CA COAST IN THE PACIFIC. WITHIN THE LARGE SCALE TROUGH OVER THE LOCAL AREA...THERE ARE FEW SMALLER SCALE SHORTWAVE TROUGHS OF INTEREST...ONE OF WHICH IS CURRENTLY ORIENTED SOUTHWEST-NORTHEAST FROM SOUTHWEST KS- NORTHERN MO...AND IS EXITING THE SOUTHEAST CWA AT THIS TIME. MEANWHILE...ANOTHER CLIPPER-TYPE NORTHWEST-FLOW SHORTWAVE IS IN THE PROCESS OF DROPPING SOUTHWARD INTO THE DAKOTAS/MN...WITHIN THE EXIT REGION OF A STOUT 120+KT NORTHERLY JET STREAK EVIDENT AT 300 MILLIBARS THAT IS CURRENTLY POKING SOUTHWARD INTO MT OUT OF SASKATCHEWAN. AT THE SURFACE...09Z OBJECTIVE ANALYSIS AND AUTOMATED OBS REVEAL A FAIRLY UNIFORM FIELD OF WESTERLY BREEZES GENERALLY 5-10 MPH ACROSS THE CWA...DRIVEN WITHIN A FAIRLY WEAK PRESSURE GRADIENT BETWEEN A 1029MB HIGH CENTERED OVER THE NEB/CO BORDER AREA AND EXTENDING SOUTHEAST ACROSS KS...AND A 1015MB LOW CENTERED OVER NORTHWEST MN ASSOCIATED WITH THE AFOREMENTIONED CLIPPER. TEMP-WISE EARLY THIS MORNING...AS WESTERLY BREEZES HAVE BECOME MORE ESTABLISHED MOST PLACES HAVE LARGELY LEVELED OFF THE NOCTURNAL DROP OR EVEN RISEN SOMEWHAT FROM VALUES EARLIER IN THE NIGHT...BUT GIVEN THE CLEAR SKIES...SOME LOCALIZED DROPS ARE STILL LIKELY BEFORE THE NIGHT IS THROUGH. ACTUAL LOWS FOR THE NIGHT ALREADY HAVE BEEN...OR WILL EVENTUALLY BE...SOMEWHERE BETWEEN 15-21 ACROSS MOST OF THE CWA. FOR THE DAYTIME HOURS TODAY...THE MAIN STORY IN THE MID-UPPER LEVELS INVOLVES THE SOUTH-SOUTHEAST PROGRESSION OF THE AFOREMENTIONED CLIPPER SYSTEM...WHICH WILL MAINLY TAKE AIM ON THE MN/IA REGION AS THE MAIN VORTICITY MAXIMUM AT 500MB ENDS UP OVER NORTHERN MN BY 00Z/6PM TODAY. GIVEN THE TRACK OF THIS SYSTEM AND ITS FORCING FIELDS...ANY LIGHT PRECIP TODAY SHOULD MAINLY FOCUS ALONG A TRACK FROM EASTERN SD ACROSS SOUTHERN MN/NORTHERN IA...AND MAYBE AS FAR SOUTHWEST AS EXTREME NORTHEAST NEB. ALONG THESE SAME LINES...THE VAST MAJORITY OF THE CWA SHOULD SEE NOTHING MORE THAN LIMITED MID-HIGH CLOUD COVER TODAY...WITH SKIES AVERAGING OUT TO NO WORSE THAN MOSTLY SUNNY. THAT BEING SAID...MODELS SUCH AS THE 06Z NAM AND TO A GREATER EXTENT THE 08Z RAP 13 SHOW THAT THE SOUTHWEST EDGES OF WHAT COULD BE A FAIRLY SOLID BATCH OF LOWER STRATUS COULD COME VERY CLOSE TO INFILTRATING A FEW COUNTIES IN THE FAR NORTHEAST CWA SUCH AS NANCE/POLK...ALTHOUGH THE VAST MAJORITY OF THIS CLOUD MASS SHOULD PASS 50+ MILES EAST/NORTHEAST OF THE CWA. ALTHOUGH THE OFFICIAL FORECAST RUNS WITH THE ASSUMPTION THAT SKIES BECOME NO WORSE THAN PARTLY CLOUDY FOR A FEW HOURS IN THESE FAR NORTHEAST AREAS...THIS WILL BARE WATCHING AS THE RAP 900/850MB RELATIVE HUMIDITY FIELDS ARE CURRENTLY HANDLING UPSTREAM LOWER CLOUDS OVER NORTH CENTRAL/EASTERN SD PRETTY WELL. TURNING TO THE SURFACE SITUATION...THE MAIN FEATURE TODAY WILL BE SEVERAL HOURS OF INCREASED NORTHWEST BREEZES...AS ENHANCED LOWER LEVEL WINDS MIX DOWN TO THE SURFACE AS MIXING HEIGHTS INCREASE TO AROUND 875MB. THE PRIMARY PERIOD OF ENHANCED NORTHWEST BREEZES WILL FOCUS BETWEEN 15Z/9AM TO 22Z/4PM...WITH SUSTAINED SPEEDS 15-20 MPH AND GUSTS AT LEAST 20-25 MPH...AND GENERALLY STRONGEST ACROSS THE NORTHEAST 1/2 OF THE CWA. ALTHOUGH THIS NORTHWESTERLY WIND TECHNICALLY RESULTS IN AT LEAST WEAK COLD AIR ADVECTION ABOVE THE SURFACE EVIDENT AT 850MB...THE COMBINATION OF SUNSHINE AND DECENT MIXING SHOULD RESULT IN A CONSIDERABLY MILDER DAY...ESPECIALLY IN THOSE CENTRAL/EASTERN COUNTIES THAT REMAINED QUITE CLOUDY TUESDAY. AS HAS BEEN TYPICAL LATELY...TEMPERATURE FIELDS IN MODELS SUCH AS THE NAM12 AND ASSOCIATED GUIDANCE ARE HEAVILY CONTAMINATED BY OVER-ZEALOUS SNOW COVER INITIALIZATION. FORTUNATELY...THE HOURLY TEMP FIELD OF THE RAP13 LOOKED QUITE REASONABLE AND UNCONTAMINATED...AND THUS WAS FOLLOWED VERY CLOSELY TODAY. THIS RESULTED IN SIMILAR HIGH TEMPS TO PREVIOUS FORECAST...BUT 1-2 DEGREES WARMER IN MANY CENTRAL/SOUTHERN AREAS. THE NET RESULT IS A RANGE FROM UPPER 30S NORTH...LOW 40S CENTRAL AND MID 40S SOUTH...ALTHOUGH A RESPECTABLE 1-3 INCHES OF SNOW COVER CENTERED OVER MUCH OF FURNAS/GOSPER/HARLAN COUNTIES WILL LIKELY KEEP THOSE AREAS A BIT COOLER THAN BORDERING AREAS...GENERALLY UPPER 30S. TURNING TO THIS EVENING/TONIGHT...A RATHER QUIET AND PRECIP-FREE FORECAST CONTINUES. IN THE MID/UPPER LEVELS...MODEST HEIGHT RISES WILL BE EVIDENT AT 500MB OVER THE LOCAL AREAS...IN THE WAKE OF THE FAIRLY VIGOROUS CLIPPER SYSTEM DEPARTING EASTWARD INTO THE LOWER GREAT LEGION. MEANWHILE THOUGH...A WEAKER/MORE SUBTLE NORTHWEST- FLOW DISTURBANCE WILL GRADUALLY APPROACH THE CENTRAL PLAINS FROM THE NORTHERN ROCKIES...REACHING THE SD/NORTHWEST NEB AREA BY SUNRISE THURSDAY. LOCALLY...THE ONLY EFFECT OF THIS INCOMING WEAK WAVE WILL BE A MODEST INCREASE IN MAINLY HIGH LEVEL CLOUDS ESPECIALLY OVER NORTHERN ZONES...BUT EVEN SO...OVERNIGHT SKIES ARE FORECAST TO AVERAGE NO WORSE THAN MOSTLY CLEAR ACROSS THE MAJORITY OF THE CWA. AT THE SURFACE...WEAK PRESSURE FALLS CENTERED OVER THE DAKOTAS WILL ALLOW LOCAL BREEZES TO TRANSITION FROM NORTHWESTERLY THIS AFTERNOON TO A WEST-SOUTHWEST DIRECTION AT GENERALLY 5-10 MPH THROUGH THE OVERNIGHT HOURS. ALTHOUGH THESE WESTERLY BREEZES WILL INDUCE MODEST WARM AIR ADVECTION ALOFT EVIDENT AT 850MB...THE FAIRLY LIGHT SPEEDS WILL PROBABLY NOT BE ENOUGH TO OFFSET A DECENT TEMP DROP UNDER THE MOSTLY CLEAR SKIES. THUS TOOK A MIDDLE-GROUND APPROACH ON LOW TEMPS...MAKING VERY LITTLE CHANGE FROM PREVIOUS FORECAST VIA A MULTI-MODEL BLEND...RESULTING IN A FAIRLY UNIFORM LOW TEMPERATURE FIELD OF 16-20 ACROSS THE CWA. THIS IS GENERALLY 2-4 DEGREES MILDER THAN A BLEND OF 00Z MET/MAV GUIDANCE WHICH APPEARS TO BE A BIT TOO COLD...BUT IS NOT AS WARM AS RAW 2M TEMPS PRESENTED BY MODELS SUCH AS THE GFS/ECMWF. AS IS TYPICAL IN THESE OVERNIGHT WESTERLY WIND REGIMES THOUGH...THERE WILL LIKELY BE SCATTERED NON-DIURNAL TEMP TENDENCIES ACROSS PARTS OF THE AREA. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 407 AM CST WED DEC 25 2013 THURSDAY THROUGH NEW YEARS EVE DAY/TUESDAY. THE LATTER PART OF THE WEEK INTO THE FIRST PART OF THE WEEKEND ARE STILL SHAPING UP TO BE THE NICEST/WARMEST DAYS OF THE EXTENDED TIME FRAME. A NORTHWEST FLOW PATTERN WILL BE IN PLACE ACROSS OUR REGION WHILE THE UPPER TROUGH AND COLD AIR THROUGH THE OHIO VALLEY REGION LIFTS OUT ACROSS THE NORTHEAST CONUS. A WARMER AIRMASS WILL SETTLE IN FOR A FEW DAYS AND A DRY DOWNSLOPE WESTERLY WIND COMPONENT WILL AID IN THE TEMP WARMUP FOR OUR AREA. HIGH ON THURSDAY SHOULD AVERAGE IN THE LOW/MID 40S...WITH EVEN WARMER 50S EXPECTED FOR FRIDAY. TEMPERATURES ON SATURDAY WILL BE DEPENDENT UPON THE TIMING OF A STRONG COLD FRONTAL PASSAGE WHICH IS PROGGED TO CROSS OUR CWA DURING THE AFTN/EVENING. IF TIMING TRENDS FASTER...TEMPS WILL NOT BE AS WARM AS CURRENT FORECAST ESPECIALLY ACROSS OUR NORTHERN ZONES AND THERMAL GRADIENT WILL NEED TO BE TIGHTENED. THE 6HR PRESSURE RISES BEHIND FRONT AVERAGE 11MB AND EXPECT A PERIOD OF STRONG/GUSTY NORTH WINDS FOLLOWING FROPA AND HAVE RAMPED UP WIND SPEEDS HIGHER THAN WHAT INIT PROVIDED. MODELS ALSO SUGGEST LOW CLOUDS MOVING IN BEHIND BOUNDARY AND AS PREVIOUS DISCUSSION MENTIONED...COULD SEE SOME FLURRIES SATURDAY EVENING/NIGHT IN PRESENCE OF FRONTOGENESIS...AND IS SOMETHING TO MONITOR. A 1035MB SURFACE HIGH BUILDS SOUTH ONTO THE PLAINS SUNDAY BEHIND THE COLD FRONT AND TEMPERATURES WILL DROP BACK BELOW SEASONAL NORMALS FOR A COUPLE OF DAYS. THE AIRMASS LOOKS TO MODERATE SOME FROM LATE MONDAY INTO TUESDAY/NEW YEARS EVE DAY AND TEMPS NEAR NORMAL APPEAR REASONABLE FOR NOW. THIS BEING SAID...A COLD AIRMASS IS NOT THAT FAR AWAY AS A TROUGH DEEPENS OVER THE HUDSON BAY. && .AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1216 AM CST WED DEC 25 2013 CONFIDENCE IS HIGH IN VFR CEILING/VISIBILITY THROUGHOUT THE PERIOD...WITH ONLY VERY LIMITED AMOUNTS OF MID/HIGH CLOUD COVER...AND ANY BATCHES OF MVFR HEIGHT LOWER STRATUS EXPECTED TO REMAIN AT LEAST 60-80 MILES NORTHEAST OF KGRI. THE MAIN MODIFICATION FROM PREVIOUS TAF ISSUANCE WAS TO INCREASE SURFACE WIND SPEEDS A BIT DURING THE DAYTIME HOURS. STARTING OFF EARLY THIS MORNING...AND THEN AGAIN LATER IN THE PERIOD THIS EVENING...A GENERALLY WESTERLY BREEZE IN THE 6-9KT RANGE WILL PREVAIL. HOWEVER...FOR SEVERAL HOURS DURING THE DAY...ESPECIALLY CENTERED BETWEEN 17Z-20Z...NORTHWEST BREEZES WILL INCREASE TO SUSTAINED LEVELS AROUND 14KT WITH GUST POTENTIAL TO AROUND 23KT. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...PFANNKUCH LONG TERM...FAY AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1206 PM CST WED DEC 25 2013 .DISCUSSION... 330 AM CST SYNOPSIS...A COUPLE QUICK SNOW SYSTEMS MOVE ACROSS THE REGION THROUGH TONIGHT WITH 1 TO 2 INCHES EXPECTED PRIMARILY ALONG AND NORTH OF I-88. A BRIEF WARM UP IS EXPECTED LATE THIS WEEK BEFORE TEMPERATURES QUICKLY TUMBLE SUNDAY WITH ANOTHER CHANCE OF SNOW. FOR EXAMPLE HIGH TEMPS SATURDAY WILL BE IN THE MID 30S TO THE LOW 40S THEN LOW TEMPS SUNDAY NIGHT WILL VARY FROM -6 TO +8 ACROSS THE CWA. ADDITIONAL CHANCES OF SNOW ARRIVE EARLY NEXT WEEK...WITH TUESDAYS SYSTEM LOOKING THE MOST IMPRESSIVE. TODAY AND TONIGHT... THE LONGWAVE TROUGH AXIS STRETCHES FROM MINNESOTA THROUGH NEW MEXICO THIS MORNING WITH A SHORTWAVE TRAVELING A BIT QUICKER THAN THE LARGER WAVE. THE SHORTWAVE IS OVER EASTERN IOWA AND ASSOCIATED WITH SOME LIGHT RETURNS ON RADAR ALONG THE IL/IA STATE LINE. GUIDANCE CONTINUES TO BACK OFF ON HOW MUCH SNOW WILL DEVELOP AHEAD OF THE SHORTWAVE...BUT DECIDED TO KEEP SNOW GOING IN THE FORECAST. TEMPS HAVE COME UP TO AROUND 20 DEGREES WITH THE DGZ AT OR NEAR THE SURFACE. FORCING EXTENDS THROUGH THE DGZ FOR A COUPLE OF HOURS WITH A SATURATED SOUNDING AT THOSE LAYERS. HOWEVER...GIVEN THE DOWN PLAY IN GUIDANCE AND HOW SNOW IS STRUGGLING TO DEVELOP NOW...LOWERED STORM TOTAL SNOW AMOUNTS. WENT FOR AN INCH NORTH OF I-88...ESPECIALLY ALONG THE IL/WI STATE LINE...WITH AN INCH OR LESS EXPECTED SOUTH OF THAT. SOUTH TO SOUTHWEST WINDS GUSTING UP TO 20 KT COULD RESULT IN A LITTLE BLOWING SNOW...BUT NOT OVERLY CONCERNED SINCE ONLY EXPECTING AN INCH TODAY. THE SNOW THAT DOES FALL WILL BE VERY DRY WITH RATIOS IN EXCESS OF 20:1. HIGH TEMPS WILL BE AT FREEZING DOWN SOUTH TO THE MID 20S ALONG THE WI/IL STATE LINE. HOWEVER...WIND CHILLS WILL MAKE IT FEEL LIKE SINGLE DIGITS ALONG THE WI/IL STATE LINE TO THE TEENS DOWN SOUTH. NEXT UP IS THE LOW CURRENTLY STRETCHING FROM HUDSON BAY THROUGH NORTHWEST MINNESOTA. THE LOW PASSES OVER ONTARIO THIS AFTERNOON WITH THE UPPER LEVEL TROUGH AXIS PASSING THROUGH THIS AFTN/EVENING. EXPECTING ANOTHER BATCH OF SNOW SHOWERS TO FORM AHEAD OF THIS AS WELL. HAVE SNOW ENTERING NORTH CENTRAL IL THIS AFTN WITH A BAND SPREADING SOUTH EAST THROUGH THIS EVENING. THE DEPTH OF MOISTURE IN THE DGZ IS MUCH BETTER WITH THIS SECOND DISTURBANCE AND COULD SEE A QUICK HALF INCH TO INCH THROUGH THIS EVENING. THE HIGHEST TOTALS ARE AGAIN EXPECTED ALONG THE IL/WI STATE LINE BECAUSE THE FORCING STARTS OUT FARTHER NORTH AND DOES NOT MOVE INTO IL UNTIL THE MOISTURE IS OVER INDIANA AND MICHIGAN. FOR OVERNIGHT DID NOT MAKE ANY MAJOR CHANGES TO GOING LOW TEMPS. NOT SURE HOW MUCH OF THE AREA WILL HAVE A FRESH SNOWPACK SO TEMPS MAY HAVE TO BE LOWERED A BIT BY LATER SHIFTS. COLDER AIR ALOFT MOVES IN BEHIND THE TROUGH AXIS...LESS THAN -8C AT 925 MB...AND CLOUDS SHOULD THIN LATE TONIGHT. SO UPPER TEENS DOWN SOUTH TO SINGLE DIGITS ACROSS NORTH CENTRAL IL IS EXPECTED. OVERNIGHT...MIN WIND CHILLS WILL BE IN THE SINGLE DIGITS DOWN SOUTH TO AS LOW AS -10F NORTH OF I-88. THURSDAY AND FRIDAY... NORTHWEST FLOW ALOFT IS EXPECTED EARLY THURSDAY BUT ANOTHER TROUGH AXIS ROLLS THROUGH FRIDAY. AT THE SURFACE HIGH PRESSURE BUILDS ACROSS THE SOUTHERN U.S. WITH ITS RIDGING PASSING OVER THE REGION THURSDAY AFTN. KEPT A DRY FORECAST GOING FOR THIS PERIOD. SOUTHWEST FLOW AND WAA RAISE 925 MB TEMPS TO NEAR 0C BY FRIDAY MORNING...AND THEN TO AROUND +5 BY SATURDAY MORNING. THEREFORE HAVE TEMPS INCREASING THROUGH FRIDAY TO AROUND 30 ALONG THE IL/WI STATE LINE TO NEAR 40 ACROSS THE SOUTHERN PORTION OF THE CWA. OVERNIGHT LOWS FRIDAY LOOK TO BE IN THE 20S. SATURDAY AND SUNDAY... THE NEXT WEAK LOW IS PUSHED SOUTH THROUGH THE CWA SATURDAY EVENING AND NIGHT WITH THE UPPER LEVEL TROUGH AXIS ROTATING THROUGH SUNDAY NIGHT. THE WARM UP CONTINUES ON SATURDAY...AND TEMPERATURES MAY HAVE TO BE RAISED FURTHER SINCE GUIDANCE CONTINUES TO SUGGEST 925MB TEMPS WILL WARM TO +4 TO +8C SATURDAY AFTERNOON. THAT RELATES TO MAX TEMPS ON SATURDAY OF IN THE MID 30S TO LOW 40S. NOT EXPECTING ANY PRECIP UNTIL BEHIND THE LOW AND ITS COLD FRONT/UPPER LEVEL TROUGH AXIS SUNDAY. FIRST...TEMPERATURES DROP THROUGH THE DAY ON SUNDAY WITH HIGH TEMPS BEING MET EARLY SUNDAY MORNING. LOOKING AT TEMPS RANGING FROM SINGLE DIGITS NEAR RFD TO LOW 20S IN NORTHWEST INDIANA BY EARLY SUNDAY EVENING. SO EXPECTING ANY PRECIP THAT DOES FORM SHOULD BE SNOW. TEMPS CONTINUE TO FALL WITH 925MB TEMPS AT -15 TO -20C BY MONDAY MORNING. THEREFORE LOW TEMPS SUNDAY NIGHT WILL RANGE FROM THE SINGLE DIGITS TO AROUND -5F. NORTHWEST WINDS AROUND 10 KT WILL CREATE MIN WIND CHILLS BELOW ZERO SUNDAY NIGHT. THE COLDEST AREA WILL BE NORTH OF I-88 WHERE WIND CHILLS LOWER THAN -20F ARE POSSIBLE. FOR SNOW...THE FORCING AND MOISTURE DO NOT SEEM ALL THAT IMPRESSIVE AT THIS TIME SO NOT EXPECTING ANY MAJOR ACCUMULATION. GFS COBB OUTPUT AGREES AS IT IS ONLY SHOWING A FEW TENTHS. EXTENDED...MONDAY AND TUESDAY... MONDAY REMAINS COLD AS THE UPPER LEVEL COLD AIR LINGERS OVERHEAD...BUT WINDS TURN WSW AND BEGIN TO USHER IN WARMER AIR ALOFT MONDAY NIGHT. HIGH TEMPS ON MONDAY WILL BE IN THE SINGLE DIGITS TO THE LOWER TEENS AND WIND CHILLS DURING THE DAY BELOW ZERO. MIN WIND CHILLS MONDAY NIGHT WILL ONCE AGAIN BE BELOW ZERO. HIGH PRESSURE PASSES OVER MONDAY NIGHT WITH ANOTHER CLIPPER ARRIVES TUESDAY. THIS SYSTEM LOOKS DARE I SAY VIGOROUS...FOR BEING A WEEK AWAY. GUIDANCE DIFFERS SLIGHTLY SO ONLY UPPED POPS INTO THE CHANCE RANGE...BUT LOOKING AT LONG RANGE COBB FOR FUN INDICATES SNOWFALL OF A FEW INCHES. JEE && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * UNDER 1500FT CIGS THIS AFTERNOON WITH POSSIBLE TEMPORARY IFR. * LIGHT ACCUMULATING SNOW MOVING IN LATER THIS AFTERNOON AND EVE. * SMALL CHANCE FOR LIGHT SNOW/FLURRIES LATE IN THE DAY ON THU. //DISCUSSION...UPDATED 18Z... STRATUS OVER THE AREA IS WELL TRAPPED UNDER AN INVERSION THIS AFTERNOON. THIS WOULD INDICATE THE CONTINUED FLATLINE TREND IN OBSERVATIONS SHOULD CONTINUE...WITH A CHANCE OF STILL TEMPORARILY DROPPING TO IFR FOR CHICAGOLAND SITES. AN UPPER LEVEL DISTURBANCE THAT IS MORE IMPRESSIVE THAN THE ONE EARLY THIS MORNING WILL SWING OVER NORTHERN IL LATE THIS AFTERNOON THROUGH MID-EVE. IT CURRENTLY IS PRODUCING AN AREA OF IFR VISBYS ACROSS NORTHERN IA/SOUTHEAST MN/FAR SOUTHWEST WI. SIMILAR TEMPORARY 1 TO 1 1/2SM VISBYS ARE EXPECTED IN SNOW ACROSS THE AREA...AS FORCING HOLDS STEADY WITH THIS FEATURE...AND EVEN SOME INDICATIONS IT INCREASES. CIGS ARE LIKELY TO BOUNCE AROUND WITHIN THE SNOW...THOUGH PRIMARILY REMAIN AT OR BELOW 2000 FT. UPPER LEVEL FORCING EASES OUT OF THE REGION LATE THIS EVE/EARLY OVERNIGHT AND MVFR CIGS ARE EXPECTED TO AS WELL. THE NEXT IN THE SERIES OF NORTHWEST FLOW CLIPPER SYSTEMS IS FORECAST TO MOVE OVER THE IL/WI STATE LINE LATE IN THE DAY THU. WHILE THIS COULD END UP PRODUCING MVFR CIGS AND EVEN LIGHT SNOW/FLURRIES...ITS TOO SMALL OF A PERTURBATION TO CHASE IN A POINT FORECAST THIS FAR OUT. WINDS WILL TURN MORE WNW LATE THIS EVE AS A SURFACE COLD FRONT MOVES THROUGH. THE WINDS WILL BACK TO THE SSW ONCE AGAIN BY THU AFTERNOON. //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH IN CIGS REMAINING BELOW 1500 FT THROUGH 22Z. LOW IN WHETHER IFR WILL OCCUR. * HIGH IN SNOWFALL OCCURRING...ESPECIALLY 00Z-02Z. MEDIUM IN VISIBILITY TRENDS. * LOW IN ANY LIGHT SNOW/FLURRIES LATE ON THU. //OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z... THURSDAY NIGHT...MAINLY VFR. POSSIBLE PATCHY MVFR CIGS. THU THROUGH MON...VFR. SLT CHC -SN ON SUN AS WELL AS MON NIGHT. TUESDAY...SLT CHC -SN. MTF/BEACHLER && .MARINE... 302 AM CST HAZARDOUS WAVES/WINDS WILL FOR THE NEARSHORE WATERS AND MAY ALSO SEE OCCASIONAL GALE FORCE GUSTS IN THE NEARSHORE WATERS THRU MIDDAY. SFC RIDGE CENTERED OVER THE OHIO VALLEY CONTINUES TO DRIFT EAST TOWARDS THE MIDDLE ATLANTIC REGION...STRETCHING NORTH TO QUEBEC. MEANWHILE A TROUGH OF LOW PRESSURE OVER THE UPPER MIDWEST WILL SLIDE NORTHEAST TOWARDS CENTRAL ONTARIO THIS MORNING...THEN SLOWLY LIFT NORTHEAST ACROSS JAMES BAY BY EARLY THURSDAY MORNING. THE GRADIENT THAT WAS EXPECTED TO DEVELOP AND PRODUCE THE GALES DEVELOPED BUT REMAINED WELL NORTH OF THE LAKE ACROSS LAKE SUPERIOR...HOWEVER SOME REPORTS ACROSS THE FAR NORTHERN PORTION OF LAKE MICHIGAN INDICATE LOW END GALES. SO GIVEN THE REDUCED CONFIDENCE IN THE GALES AND LACK OF OBSERVATIONS TO SUPPORT KEEPING THE GALE WARNING GOING...HAVE OPTED TO CANCEL THE GALE WARNING EARLY. WILL HOWEVER CONTINUE TO MENTION OCCASIONAL GALE FORCE GUSTS TO 35 KT THROUGH MID MORNING...THEN THE GRADIENT WILL CONTINUE TO WEAKEN. WINDS WILL STEADILY SHIFT FROM SOUTHWEST TO WEST BY LATE THIS AFTERNOON...THEN CONTINUE TO DIMINISH TO AROUND 15 TO 25 KT. HAZARDOUS WINDS AND WAVES WILL PERSIST FOR THE NEARSHORE WATERS AND CONFIDENCE REMAINS HIGH THAT THE SMALL CRAFT ADVISORY WILL CONTINUE. IT IS POSSIBLE THAT THE SMALL CRAFT ADVISORY WILL NEED TO BE EXTENDED FOR THE INDIANA NEARSHORE WATERS AS WINDS TURN WEST...THIS MAY HELP KEEP ELEVATED WAVES LONGER FOR THIS FAR SOUTHEAST CORNER OF LAKE MICHIGAN. THE NEXT WEATHER SYSTEM TO BRING A STRONG GRADIENT TO THE LAKE WILL ARRIVE SAT...AND LIKELY PRODUCE WINDS TO 30KT. IT IS POSSIBLE A FEW GUSTS TO GALE FORCE MAY OCCUR SAT. THEN ANOTHER STRONG RIDGE OF HIGH PRESSURE WILL SLIDE SOUTH FROM CENTRAL CANADA FOR THE SECOND HALF OF THE WEEKEND AND MAY BRING A TIGHT GRADIENT TO THE LAKE. SFC RIDGE OVER THE OHIO VALLEY WILL CONTINUE TO DRIFT EAST TONIGHT...WITH A TIGHTENING GRADIENT ALONG THE WESTERN EDGE. THIS TIGHT GRADIENT WILL SLIDE OVER THE LAKE TONIGHT...PRODUCING SOUTH/SOUTHWEST GALES BETWEEN 35-40KT OVERNIGHT. THE GRADIENT CONTINUES TO SLIDE EAST WITH THE ARRIVAL OF A CLIPPER LOW PRESSURE. THIS CLIPPER WILL ALLOW THE WINDS TO BECOME WESTERLY...AND SHOULD SEE GALES COME TO AN END BY MID-MORNING WED. HOWEVER THE GRADIENT WILL REMAIN RELATIVELY STRONG AND PRODUCE WINDS TO 30KT THRU MIDDAY WED BEFORE DIMINISHING TO 15 TO 25 KT BY WED NIGHT. THE NEXT WEATHER SYSTEM TO BRING A STRONG GRADIENT TO THE LAKE WILL ARRIVE SAT...AND LIKELY PRODUCE WINDS TO 30KT. IT IS POSSIBLE A FEW GUSTS TO GALE FORCE MAY OCCUR SAT. THEN ANOTHER STRONG RIDGE OF HIGH PRESSURE WILL SLIDE SOUTH FROM CENTRAL CANADA FOR THE SECOND HALF OF THE WEEKEND AND MAY BRING A TIGHT GRADIENT TO THE LAKE. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 10 PM WEDNESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 1123 AM CST Wed Dec 25 2013 .DISCUSSION... ISSUED 948 AM CST Wed Dec 25 2013 Initial upper wave currently pushing through central Illinois. Earlier light snow ahead of this wave is now well off to the west. However, a faster shortwave, currently diving into northwest Iowa, has been producing some light snow ahead of it, from central Iowa to western Wisconsin. Morning models showing the bulk of the snow with this feature tracking just to our north, but the NAM and RAP models show potential for perhaps a tenth or two of snow north of I-74 during the evening hours. Have made some updates to the snow trends in the forecast, namely to add some low PoP`s in the far northern CWA this evening. Have also removed most of the flurries after midnight, as the shortwave should be well east of us by that point. Temperature forecasts generally on track and only needed some minor tweaks. Geelhart && .AVIATION... ISSUED 1123 AM CST Wed Dec 25 2013 IFR conditions spreading southward over the TAF sites late this morning behind the earlier upper wave. Surface obs showing IFR ceilings back into central Iowa, just ahead of another fast moving wave, before ceilings come back up to around 1500-2000 feet. Some light snow over Iowa expected to track through the northern third of Illinois late afternoon/early evening. May see some reduced visibilities at times at KPIA/KBMI from these snow showers. VFR conditions should start working their way eastward across the area overnight. Geelhart && .PREV DISCUSSION... ISSUED 209 AM CST Wed Dec 25 2013 No major storm systems are anticipated across central Illinois over the next week, as a prevailing northwesterly flow pattern brings periodic flurries/very light snow and bouts of very cold air. SHORT TERM...Today through Friday First weak system embedded within the northwesterly flow is currently approaching the Mississippi River as an elongated vorticity max stretching from Wisconsin to the Texas panhandle. This feature has been shearing/weakening as it tracks eastward, and with limited moisture to work with, has produced only very meager amounts of light snow across parts of central and northern Iowa. Stronger lift and steadier snows have been confined further north across Minnesota into Wisconsin. Despite models insisting on precip development further south, have not seen much evidence upstream over Missouri, so have decided to downplay the snow chances this morning. Will maintain low chance PoPs along/north of the I-74 corridor through midday, where a dusting is possible. Further south, will only mention scattered flurries across the remainder of the KILX CWA. Once the initial wave passes, another disturbance currently dropping into North Dakota will skirt across northern Illinois this evening. Due to increasing synoptic lift ahead of this feature, have added flurries to the forecast along/west of the Illinois River late this afternoon, then everywhere tonight. Upper pattern will begin to go zonal by the end of the week, signaling a brief warming trend that will help boost highs well into the 30s and even the lower 40s south of I-70 by Friday. LONG TERM...Saturday through Tuesday Warmest day of the forecast period will be Saturday, as southwesterly winds ahead of an approaching Arctic cold front allow temps to reach the 40s across the board. Models have been consistent in bringing the cold front through central Illinois on Sunday, with each run suggesting clouds and perhaps a few snow-showers. Will carry low chance PoPs for snow on Sunday accordingly. Once front passes, another chunk of very cold air will arrive early next week as the upper flow pattern returns to northwesterly. With 850mb temps progged to fall into the -12 to -14C range, highs will drop back into the teens and lower 20s by Monday. After that, will have to watch the next approaching clipper system for late Monday into Tuesday. Latest models are slower and a bit further north with this system, but still suggest a period of light snow will be possible across the northern CWA late Tuesday. Timing of these features this far out is quite difficult, so will only mention very low chance POPs across the north at this time. Barnes && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
Area Forecast Discussion National Weather Service Lincoln IL 949 AM CST Wed Dec 25 2013 .DISCUSSION... ISSUED 948 AM CST Wed Dec 25 2013 Initial upper wave currently pushing through central Illinois. Earlier light snow ahead of this wave is now well off to the west. However, a faster shortwave, currently diving into northwest Iowa, has been producing some light snow ahead of it, from central Iowa to western Wisconsin. Morning models showing the bulk of the snow with this feature tracking just to our north, but the NAM and RAP models show potential for perhaps a tenth or two of snow north of I-74 during the evening hours. Have made some updates to the snow trends in the forecast, namely to add some low PoP`s in the far northern CWA this evening. Have also removed most of the flurries after midnight, as the shortwave should be well east of us by that point. Temperature forecasts generally on track and only needed some minor tweaks. Geelhart && .AVIATION... ISSUED 556 AM CST Wed Dec 25 2013 MVFR clouds will prevail for the first few hours of this TAF period as a fast moving clipper produces light snow for a period of an hour or so. Snow has already ended at PIA, and is just affecting SPI. Over the next 2 hours, BMI, DEC and CMI will see the snow move through. IFR clouds are poised to develop 2 hours after the snow ends, based on observation trends upstream. The NAM and RAP soundings show IFR conditions could persist into the afternoon, and possibly until near sunset. MVFR conditions could develop as mixing increases this afternoon, but we generally held off the return to MVFR clouds until 22-23z. Some clearing should develop from west to east this evening, as the drier air returns to lower levels. Clearing could reach PIA as early as 01z and progress to CMI by 07z. Winds will be primarily southwest until this evening when they shift to the west and increase from around 10-12kt to 14-16kt. Shimon && .PREV DISCUSSION... ISSUED 209 AM CST Wed Dec 25 2013 No major storm systems are anticipated across central Illinois over the next week, as a prevailing northwesterly flow pattern brings periodic flurries/very light snow and bouts of very cold air. SHORT TERM...Today through Friday First weak system embedded within the northwesterly flow is currently approaching the Mississippi River as an elongated vorticity max stretching from Wisconsin to the Texas panhandle. This feature has been shearing/weakening as it tracks eastward, and with limited moisture to work with, has produced only very meager amounts of light snow across parts of central and northern Iowa. Stronger lift and steadier snows have been confined further north across Minnesota into Wisconsin. Despite models insisting on precip development further south, have not seen much evidence upstream over Missouri, so have decided to downplay the snow chances this morning. Will maintain low chance PoPs along/north of the I-74 corridor through midday, where a dusting is possible. Further south, will only mention scattered flurries across the remainder of the KILX CWA. Once the initial wave passes, another disturbance currently dropping into North Dakota will skirt across northern Illinois this evening. Due to increasing synoptic lift ahead of this feature, have added flurries to the forecast along/west of the Illinois River late this afternoon, then everywhere tonight. Upper pattern will begin to go zonal by the end of the week, signaling a brief warming trend that will help boost highs well into the 30s and even the lower 40s south of I-70 by Friday. LONG TERM...Saturday through Tuesday Warmest day of the forecast period will be Saturday, as southwesterly winds ahead of an approaching Arctic cold front allow temps to reach the 40s across the board. Models have been consistent in bringing the cold front through central Illinois on Sunday, with each run suggesting clouds and perhaps a few snow-showers. Will carry low chance PoPs for snow on Sunday accordingly. Once front passes, another chunk of very cold air will arrive early next week as the upper flow pattern returns to northwesterly. With 850mb temps progged to fall into the -12 to -14C range, highs will drop back into the teens and lower 20s by Monday. After that, will have to watch the next approaching clipper system for late Monday into Tuesday. Latest models are slower and a bit further north with this system, but still suggest a period of light snow will be possible across the northern CWA late Tuesday. Timing of these features this far out is quite difficult, so will only mention very low chance POPs across the north at this time. Barnes && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
258 PM EST WED DEC 25 2013 .SYNOPSIS... AFTER A ROUND OF SNOW OVERNIGHT INTO THURSDAY...CONDITIONS SHOULD BE DRY UNTIL ANOTHER COLD FRONT COMES THROUGH SUNDAY AND MONDAY. TEMPERATURES WILL RISE TO ABOVE NORMAL VALUES FOR THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY/... CLOUD SHIELD CONTINUES TO ADVANCE FROM THE WEST THIS AFTERNOON...SLOWLY OVERRUNNING THE ENTIRE FORECAST AREA. WHILE THE PREVIOUS FORECAST ANTICIPATED A ROUND OF SNOW LATE TONIGHT INTO THURSDAY MORNING WITH AN UPPER LEVEL TROUGH...LATEST HIGH-RESOLUTION MODEL RUNS ARE INDICATING THAT A SECOND ROUND OF SNOW WILL OCCUR BEFORE THE TROUGH PASSAGE. WHILE THE TROUGH REMAINS OVER MICHIGAN DURING THE EVENING HOURS...AN UPPER LEVEL SHORTWAVE WILL MOVE IN FROM THE SOUTHWEST. IN ADDITION...MULTIPLE RUNS OF THE RAP SHOW FRONTOGENESIS DEVELOPING AT 850MB...AND TO A LESSER EXTENT IN THE 12Z NAM. SEVERAL HIRES MODELS SHOW A BAND OF SNOW DEVELOPING ALONG THE FRONTOGENESIS BY LATE EVENING ACROSS SOUTHERN OHIO EXTENDING INTO NORTHWESTERN PENNSYLVANIA. THIS BAND SHOULD SLOWLY MOVE TO THE EAST DURING THE OVERNIGHT HOURS. OVERNIGHT SNOWFALL TOTALS COULD REACH AN INCH...WITH ISOLATED TWO INCH AMOUNTS POSSIBLE. LITTLE CHANGE HAS BEEN MADE TO THE PORTION OF THE FORECAST WITH THE PASSAGE OF THE UPPER TROUGH. TIMING AND ACCUMULATIONS APPEAR TO BE SIMILAR TO THAT OF THURSDAY MORNING...WITH GENERAL TOTALS AROUND AN INCH WITH ANOTHER CHANCE FOR ISOLATED TWO INCH AMOUNTS. HOWEVER...12Z MODELS HAVE INCLUDED SLIGHT REDUCTIONS IN SNOWFALL TOTALS. BULK OF PRECIPITATION SHOULD HAVE MOVED EAST OF THE REGION BY NOON...ALTHOUGH THE TYPICAL UPSLOPE/LAKE EFFECT AREAS SHOULD EXPECT SCATTERED SNOW SHOWERS TO CONTINUE INTO THE AFTERNOON. TEMPERATURES SHOULD BE MILD OVERNIGHT...WITH HIGHS A FEW DEGREES BELOW NORMAL. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... MINIMAL CHANGE WAS NEEDED IN THE SHORT TERM AS MODELS SHOW FAIRLY DECENT CONTINUITY WITH PREVIOUS RUNS. HIGH PRESSURE WILL BEGIN TO BUILD IN THURSDAY NIGHT FROM THE SOUTH AND WILL MARK THE BEGINNING OF A RELATIVELY DRY PERIOD FOR THE FORECAST AREA. WINDS WILL BECOME WEST SOUTHWEST AS HIGH PRESSURE SHIFTS TO THE SOUTH. THIS WILL RESULT IN TEMPERATURES WARMING TO SLIGHTLY ABOVE NORMAL AND CONTINUED DRY CONDITIONS. BASED ON LATEST SOUNDINGS...WE MAY ACTUALLY SEE A FAIR AMOUNT OF SUNSHINE ON SATURDAY. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... A QUICK WARM UP WILL ENSUE SUNDAY AHEAD OF A FAIRLY STRONG COLD FRONT. SYSTEM WILL BE MOISTURE STARVED FOR THE MOST PART AND SCATTERED RAIN AND SNOW SHOWERS LATE DAY SUNDAY WILL CHANGE TO ALL SNOW SHOWERS FOR SUNDAY NIGHT AS MUCH COLDER AIR ONCE AGAIN SURGES SOUTH ACROSS THE REGION. EXTENDED CHC POPS FOR SNOW SHOWERS INTO MONDAY NIGHT ESPECIALLY FOR THE RIDGES. NEXT CLIPPER THEN FLIES SOUTHEAST IN NORTHWEST FLOW ALOFT FOR TUESDAY...AND THIS IS ANOTHER SYSTEM THAT WILL HAVE LITTLE MOISTURE TO WORK WITH AND SLGT CHC POPS CONTINUED. BY MID WEEK SURFACE RIDGE WILL BRING DRY AND COLD CONDITIONS. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... BREAKS IN THE VFR MID DECK WILL FILL IN BY EARLY EVENING. BAND OF SNOW WILL DEVELOP OVER SOUTHERN OHIO LATE THIS EVENING AND EXTEND NORTHEAST INTO NORTHWEST PENNSYLVANIA. CURRENT MVFR VISIBILITIES IN TAFS WITH THIS BAND MAY BE TOO OPTIMISTIC...WITH IFR VISIBILITIES CERTAINLY POSSIBLE. AT THIS POINT...IFR VIS WAS HELD OFF IN TAFS UNTIL A SECOND ROUND OF SNOW ARRIVES WITH AN UPPER LEVEL TROUGH AROUND SUNRISE ON THURSDAY. SNOW IS EXPECTED TO BE LIGHTER AT ZZV/MGW AND HAVE ONLY GONE WITH MVFR/VFR VIS AT THOSE TERMINALS. BY EARLY THURSDAY AFTERNOON MVFR CIGS WILL BE HOLDING ON AT MOST SITES IN FLURRIES...ALTHOUGH FKL/DUJ MAY CONTINUE TO KEEP IFR CIGS THROUGH THE REST OF THE AFTERNOON. .OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/... IMPROVEMENT TO VFR IS EXPECTED ONCE AGAIN THURSDAY NIGHT ALTHOUGH MVFR CIGS MAY LINGER ACROSS THE NORTH. GENERAL VFR FRIDAY THROUGH SATURDAY. AN APPROACHING COLD FRONT MAY BRING RESTRICTIONS ACROSS THE NORTH LATE DAY SUNDAY AND MONDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
449 PM EST WED DEC 25 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 446 PM EST WED DEC 25 2013 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW UPR TROF CENTERED OVER CENTRAL NAMERICA BTWN RDGING OVER THE ERN CONUS EXTENDING INTO QUEBEC AND A STRONGER MEAN RDG OVER THE W. VERY CHILLY AIR LINGERS OVER THE UPR LKS WITH H85 TEMPS IN THE -15C TO -20C RANGE. THERE ARE SEVERAL SHRTWVS OF INTEREST EMBEDDED WITHIN THIS UPR TROF. THE FIRST IS MOVING INTO WRN UPR MI EARLY THIS AFTN AND ACCOMPANIED BY AN AREA OF COLDER CLD TOPS SHOWN ON IR STLT IMAGERY. IN CONCERT WITH SOME DEEPER MSTR TO H5 SHOWN ON THE 12Z INL RAOB...SCT-NMRS -SHSN IMPACTED MUCH OF THE CWA INTO EARLY THIS AFTN BEFORE LARGER SCALE FORCING ASSOCIATED WITH THE SHRTWV THAT CAUSED THE SN LAST NGT/THIS MRNG EXITED THE AREA. BUT LARGER SCALE QVECTOR DVGC HAS WEAKENED THIS SHRTWV/WARMED CLD TOP TEMPS...DIMINISHING THE SHSN DURING THE LAST COUPLE OF HRS. IN FACT...THERE HAS BEEN SOME CLRG THIS AFTN. A SECOND SHRTWV IS DIGGING SSEWD THRU MANITOBA...ACCOMPANIED BY A 120KT H3 JET MAX. YET ANOTHER SHRTWV RIDING OVER THE TOP OF THE WRN RDG IS PUSHING INTO BRITISH COLUMBIA. MAIN FCST CONCERNS IN THE SHORT TERM ARE POPS/SN AMNTS/NEED FOR HEADLINES ASSOCIATED WITH PARADE OF SHRTWS PASSING THRU THE UPR LKS WITHIN THE PERSISTENT UPR TROF. TNGT...AS SHRTWV DIGGING SEWD THRU MANITOBA PASSES INTO WI TNGT...EXPECT A WSHFT TO THE NW TO DRIVE A LO PRES TROF ONSHORE. ALTHOUGH THE 12Z NAM/GFS SHOW THE SHARPEST DPVA/H7-3 QVECTOR CNVGC PASSING TO THE SW OF THE CWA CLOSER TO THE ACCOMPANYING H3 JET CORE...NAM FCST SDNGS SHOW INVRN BASE AT CMX RISING TO NEAR 7K FT THIS EVNG IN THE PRESENCE OF DEEPER MSTR. WITH VERY COLD LLVL AIR LINGERING NEAR THE SFC...THE SFC WSHFT FM THE WSW OVER THE INTERIOR WL NOT BE AS DRAMATIC AS OVER/NEAR LK SUP. THE RESULT WL BE SHARPENED LAND BREEZE LLVL CNVGC NEAR LK SUP...FIRST OVER THE NW CWA THIS EVNG AND THEN ALSO OVER THE FAR ERN CWA LATER. SINCE THE ACCOMPANYING UVV IS CENTERED WITHIN THE DGZ AS SHOWN ON NAM FCST SDNGS...SN/WATER RATIOS SHOULD BE AS HI AS 25-30:1. RELATIVELY LGT WINDS NO HIER THAN 10-15 KTS SHOULD RESULT IN MINIMAL FRACTURING OF THE SN FLAKES. CONSIDERING THE FRBL SN/WATER RATIOS AND POTENTIAL FOR ENHANCED SN NEAR LAND BREEZE CNVGC ZONES...OPTED TO ISSUE AN LES ADVY FOR THE KEWEENAW AND ALGER/LUCE COUNTIES FOR MAINLY THE AREAS NEAR LK SUP E FM GRAND MARAIS TO CRISP POINT. ALSO CONCERNED AT LEAST NORTHERN ONTONAGON COUNTY COULD SEE SOME HEAVIER SN TNGT... BUT OPTED NOT TO INCLUDE THAT ZONE IN THE HEADLINE SINCE HEAVIER SN IS LIKELY TO IMPACT ONLY THE RELATIVELY UNPOPULATED NRN PORTION OF THIS COUNTY. SINCE THERE HAS BEEN PARTIAL CLRG OVER MUCH OF THE CWA LATE THIS AFTN...OPTED TO LOWER MIN TEMPS A BIT WITH THE EXPECTATION TEMPS COULD FALL QUICKLY BEFORE A WSHFT TOWARD THE NW ABV THE SHALLOW COLD AIR NEAR THE SFC BRINGS IN MORE CLDS. BACKING LLVL FLOW LATE AHEAD OF APRCHG HI PRES RDG/SHRTWV RDG FOLLOWING THE DEPARTING DIGGING SHRTWV MAY BRING SOME PARTIAL CLRG/MORE UNMODIFIED ARCTIC AIR TO THE INTERIOR W NEAR THE WI BORDER AS WELL. THU...NEXT SHRTWV NOW TOPPING UPR RDG OVER WRN CANADA IS PROGGED TO DIG SEWD THRU MN IN PERSISTENT NW FLOW ALF...WITH SHARPEST DEEP LYR QVECTOR CNVGC PASSING TO THE SW OF UPR MI. LLVL WINDS ARE FCST TO BACK SLOWLY TOWARD THE WSW OVER MAINLY THE WRN CWA THRU THE DAY AHEAD OF THIS DISTURBANCE...SO LES SHOULD BECOME CONFINED TO MAINLY THE KEWEENAW. ALTHOUGH SN TOTALS OVER KEWEENAW COUNTY TNGT MAY NOT BE AS IMPRESSIVE AS IN HOUGHTON COUNTY...THE NRN PORTION OF THE KEWEENAW WL LIKELY SEE MORE SN ON THU...ESPECIALLY LATER IN THE DAY. WITH A MORE 300 DEGREE FLOW LINGERING THRU MUCH OF THE DAY TO THE E...EXPECT THE MOST WDSPRD AND HEAVIER LES TO IMPACT ERN ALGER AND THE THE N HALF OF LUCE COUNTY. OVER THE SCENTRAL...ARRIVAL OF HI PRES RDG AHEAD OF THE SHRTWV WL BRING PARTIAL SUNSHINE FILTERED BY MID/HI CLDS ASSOCIATED WITH THE MSTR STARVED SHRTWV. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 446 PM EST WED DEC 25 2013 THURSDAY NIGHT...WITH PASSAGE OF SFC RIDGE...LINGERING LES WILL END AS WINDS SHIFT SW/OFFSHORE. EXPECT LES WITH THE STRONGER LOW LEVEL CONV OVER THE FAR NORTHEAST CWA...PER HIGH RES MODELS...COULD STILL PRODUCE A FEW MORE INCHES OF SNOW. HOWEVER...THE SNOW OVER THE KEWEENAW SHOULD GENERALLY BE LIGHT...WITH AN INCH OR LESS. FRIDAY INTO FRI NIGHT...WAA WILL DOMINATE WITH A TEMPORARY TRANSITION TOWARD A MORE ZONAL PATTERN. THERE MAY BE PERIOD OF LIGHT PCPN ASSOCIATED WITH ISENTROPIC LIFT THROUGH THE 850-700 MB FRONTAL ZONE. THE DEEPEST MOISTURE AND BEST CHANCE FOR SATURATION WITH MEASURABLE PCPN IS EXPECTED FROM THE KEWEENAW INTO THE NE CWA. THERE MAY BE ENOUGH OF A WARM LAYER...PER NAM/GFS...FOR SOME LIGHT MIXED PCPN. HOWEVER GIVEN MODEL DIFFERENCES COMAPRED TO THE COLDER ECMWF...CONFIDENCE WAS NOT HIGH ENOUGH TO INCLUDE ANY SLEET OR FREEZING RAIN AT THIS TIME. SAT THROUGH SAT NIGHT...WARMING WILL CONTINUE AHEAD OF A SHRTWV TRACKING FROM BC NW TO THE NRN PLAINS. MOST LOCATIONS SHOULD CLIMB TO NEAR 30. HOWEVER...A COLD FRONT DRIFTING SOUTH ACROSS THE CWA MAY INFLUENCE MAX TEMPS DEPENING ON HOW QUICKLY IT MOVES N-S THROUGH THE AREA FROM THE LATE MORNING THROUGH THE AFTERNOON. MODEL DIFFERENCES REMAIN REGARDING THE STRENGTH/TIMING OF THE SHRTWV AND SFC TROUGH DEVELOPMENT TO THE SOUTH. AFTER THE ARCTIC COLD FRONT MOVES THROUGH WITH 850 MB TEMPS DROPPING TO AROUND -18C BY 12Z/SUN...LAKE ENHANCED TO LES WILL DEVELOP. A PERIOD OF MODERATE TO EVEN HEAVY SNOW MAY BE POSSIBLE FOR NORTH FLOW FAVORED SNOWBELTS IF THE STRONGER SHRTWV/TROUGH DEVELOPS. SUN-WED...AFTER WINDS GRADUALLY BACK ON SUN AS HIGH PRES BUILDS TOWARD THE AREA...PERSISTENT LES WILL THEN DEVELOP FROM SUN THROUGH TUE...MOSTLY FOR W TO WNW WIND FAVORED SNOWBELTS...AS ACRTIC AIR SETTLES OVER THE AREA WITH 850 MB TEMPS TO AROUND -25C. BY WED THERE IS MORE UNCERTAINTY WITH THE WIND DIRECTION GIVEN THE POTENTIAL FOR CLIPPER SHRTWVS(ECMWF) THAT MAY BRING BACKING WINDS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1228 PM EST WED DEC 25 2013 CMX...EXPECT PREDOMINANT IFR CONDITIONS HERE WITH A W UPSLOPE FLOW TO GIVE WAY TO A PERIOD OF LOWER LIFR CONDITIONS TNGT WITH THE ARRIVAL OF A LO PRES TROF/WSHFT TO MORE WNW. ALTHOUGH CONDITIONS WL IMPROVE LATER TNGT/THU MRNG FOLLOWING THE EXIT OF THIS TROF...IFR VSBYS SHOULD PERSIST THRU 18Z THU WITH LK EFFECT -SHSN LINGERING. IWD...EXPECT MVFR TO VFR CONDITIONS THIS AFTN TO GIVE WAY TO A PERIOD OF IFR VSBYS TNGT WITH THE APRCH/PASSAGE OF A LO PRES TROF. FOLLOWING THE EXIT OF THIS TROF LATER TNGT...CONDITIONS WL IMPROVE TO MVFR AND THEN TO VFR ON THU WITH THE APRCH OF A HI PRES RDG/ BACKING LLVL FLOW. SAW...EXPECT VFR TO OCNL MVFR CONDITIONS THIS AFTN TO GIVE WAY TO A PERIOD OF MVFR CIGS TNGT ASSOCIATED WITH A LO PRES TROF PASSAGE. VFR WX SHOULD THEN FOLLOW LATE TNGT INTO THU WITH A DOWNSLOPE W WIND FOLLOWING THE TROF. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 446 PM EST WED DEC 25 2013 EXPECT W TO NW WINDS UP TO 25 KTS TONIGHT TO DIMINISH TO UNDER 20 KTS ON THU WITH APPROACH OF A HI PRES RIDGE/WEAKER PRES GRADIENT. FOLLOWING THE PASSAGE OF AN ARCTIC COLD FRONT...NORTH GALES ARE POSSIBLE. HEAVY FREEZING SPRAY IS ALSO EXPECTED FROM SATURDAY NIGHT INTO TUESDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY FROM 1 AM TO 7 PM EST THURSDAY FOR MIZ006-007. LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THURSDAY FOR MIZ001-003. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...JLB AVIATION...KC MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1228 PM EST WED DEC 25 2013 .UPDATE... ISSUED AT 1043 AM EST WED DEC 25 2013 CANX GOING WARNING FOR LUCE COUNTY EARLY GIVEN EXIT OF ENHANCED CLD SHOWN ON IR STLT LOOP AND SHIFT OF HEAVY LES BAND TO THE E INTO CHIPPEWA COUNTY PER CNDN MONTREAL RIVER RADAR. NEARBY SFC OBS ALSO SHOW A WSHFT TO THE WSW AT ERY AND NAUBINWAY...CONSISTENT WITH THE PASSAGE OF THE HEAVIER BAND TO THE E. SOME SCT SHSN WL CONT THRU THE DAY IN LUCE COUNTY...BUT ANY ADDITIONAL ACCUM SHOULD BE LESS THAN AN INCH. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 531 AM EST WED DEC 25 2013 PARADE OF SHORTWAVES IN STORE ACROSS UPPER GREAT LAKES FOR NEXT 24 HOURS AS UPR LAKES REMAINS ON PERIFERY OF MEAN TROUGH. LEAD SHORTWAVE AND MOISTURE ADVECTION HAS RESULTED IN WIDESPREAD SNOW WEST TO EAST ACROSS UPR MICHIGAN. LIMITED REPORTS BUT SEEMS MOST SNOW /2-3 INCHES/ OCCURRED IN SCNTRL CWA ON NORTHERN FRINGE OF BETTER DEEP LAYER Q-VECTOR CONVERGENCE. OTHER AREA OF HIGHER SNOWFALL IS DUE TO LAKE ENHANCEMENT OFF LK MICHIGAN OVER FAR EAST CWA...JUST TO EAST OF MANISTIQUE TOWARD NEWBERRY. MQT AND APX RADARS SHOWED MAIN BAND OF LAKE EFFECT AS EARLY AS 06Z WITH ECHOES OVER NORTHERN LK MICHIGAN UP TO 10KFT SUGGESTING HEALTHY BAND OF SNOW. HAVING TO DO A LOT OF INTERPOLATION AND EXTRAPOLATION IN DETERMINING WHAT IS GOING ON IN THSES AREAS USING MDOT WEBCAMS AND FREQUENT CALLS TO THE ISQ AND ERY AWOS /LONG-LINE TRANSMISSION OF MANY AWOS ACROSS THE REGION IS DOWN RIGHT NOW/. WILL HAVE TO WAIT TO GET REPORTS LATER THIS MORNING...BUT AS BEST WE CAN TELL SEEMS THE HEAVIEST AND MOST PERSISTENT SNOW HAS OCCURRED FROM NEAR BLANEY PARK TOWARD MCMILLAN IN SOUTHWEST LUCE COUNTY. JUST WITHIN LAST HOUR...HEAVY SNOW IS PUSHING TOWARD NEWBERRY. GEM-REGIONAL AND HRRR PEGGING THINGS PRETTY WELL. BOTH SHOW THE MAIN CONVERGENCE BAND AND HEAVY SNOW MOVING STEADILY TO THE EAST THIS MORNING...PROBABLY OUT OF ERY BY 15Z IF NOT SOONER. LOWERED SNOW AMOUNTS SLIGHTLY OVER SOUTHERN LUCE...BUT OVERALL WILL KEEP HEADLINES AS IS FOR NOW AS WINDS ALONG LK MICHIGAN SHOWING GUSTS OVER 30 MPH /PROBABLY REPRESENTATIVE WHAT IS OCCURRING WITHIN THE SNOW BAND FARTHER INLAND/ WHICH WOULD BE RESULTING IN BLOWING AND DRIFTING OF THE SNOW. WILL RE-EVALUATE THE HEADLINES TOWARD DAYBREAK TO SEE IF SOME CHANGES ARE NEEDED. ELSEWHERE...EXPECT THE WIDESPREAD SNOW TO TAPER OFF BY DAYBREAK. GUSTY WINDS COULD EASILY BLOW THE FLUFFY SNOW AROUND SO PUT OUT AN SPS MAINLY EMPHASIZING DIFFICULT TRAVEL IN SOME AREAS THIS MORNING. LATER TODAY...ANOTHER SHORTWAVE CURRENTLY SLIDING ACROSS MINNESOTA MAY RESULT IN A CONTINUATION OF SOME LGT SNOW OR FLURRIES FOR MOST OF THE AREA. INTO TONIGHT...EMPHASIS FOR LAKE EFFECT SHIFTS TO THE SNOWBELTS OF WESTERN AND EVENTUALLY FAR NORTHEAST UPR MICHIGAN...MAINLY EAST OF MUNISING AND TO THE NORTH OF NEWBERRY. LAST SHORTWAVE FAIRLY STRONG BUT DIRECT IMPACTS MOSTLY STAY TO THE SOUTH OF UPR MICHIGAN AS WAVE TRACKS FM CNTRL MN ACROSS WI. WAVE MAY ACT TO HOLD TROUGHING IN PLACE OVER SCNTRL LK SUPERIOR RESULTING IN MAINLY WSW WINDS OVER MUCH OF THE LAND AREAS AND NW WINDS OVER LK SUPERIOR. FOR THIS REASON...LEANED TOWARD NCEP WRF-ARW/NMM IDEA OF CONVERGENCE BAND TRYING TO GET GOING OVER THE KEWEENAW TOWARD EASTERN ALGER COUNTY AFTER LATE EVENING. SOUNDINGS FOR TONIGHT SHOW DRYING AND SUBSIDENCE ABOVE H8 BUT BULK OF LAKE EFFECT CONVECTIVE LAYER IS WELL WITHIN THE DGZ RESULTING IN SLR/S SOLIDLY OVER 20:1 AND MAYBE PUSHING TOWARD 30:1. IF CONVERGENCE IS STRONGER...MAY SEE ADVY LEVEL SNOW AMOUNTS FOR PORTIONS OF KEWEENAW AND PERHAPS AS FAR SOUTH AS HIGHER TERRAIN OF NORTHERN ONTONAGON COUNTY...INCLUDING WHITE PINE AND ROCKLAND. SINCE IT WILL BE VERY FLUFFY SNOW AND WINDS/BLSN WILL NOT BE TOO MUCH OF A FACTOR AND SINCE SOME PLACES IN KEWEENAW ARE WELL OVER 100 INCHES ALREADY FOR SEASON...EVENT DOES NOT APPEAR TO SUPPORT THE NEED FOR ADVY AS IT STANDS NOW. DAYSHIFT CAN RE-EVALUATE BUT DID NOT ISSUE AT THIS TIME. HEAVIER LAKE EFFECT WILL ALSO AFFECT THE SNOWBELTS OF THE NORTHEAST CWA WITH MOST SNOW NOT OCCURRING UNTIL WELL AFTER MIDNIGHT ONCE WINDS SHIFT MORE WNW. INLAND FROM THE LAKE EFFECT ISSUES...SKIES MAY TRY TO CLEAR OUT IF THE WINDS ARE MORE WSW THAN WNW. IF THIS OCCURS...TEMPS OVER INLAND WEST AND CNTRL AND MAYBE EVEN EASTERN CWA COULD FALL WELL BELOW ZERO. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 531 AM EST WED DEC 25 2013 WARMING WILL OCCUR LATE THIS WEEK AS FLOW BRIEFLY BECOMES ZONAL ACROSS THE NRN CONUS. HOWEVER...OVER THE NEXT 7 DAYS...THE CURRENT RATHER DISORGANIZED POLAR VORTEX LOCATED WELL N IN NRN CANADA WILL REORGANIZE/EXPAND AND DROP S TO THE VCNTY OF HUDSON BAY. AS A RESULT...ARCTIC AIR WILL AGAIN SPREAD S INTO THE UPPER GREAT LAKES NEXT WEEK...AND THERE MAY BE A COUPLE OF SHOTS OF BITTER COLD AIR. PATTERN DOES NOT LOOK FAVORABLE FOR MUCH IN THE WAY OF WIDESPREAD SYNOPTIC SNOWFALL OVER THE NEXT 7 DAYS. NEXT WEEK...LES WILL BE THE MAIN PCPN CONCERN...MOSTLY FOR SNOWBELTS FAVORED BY W TO NW WINDS. BEGINNING THU...WNW FLOW LES WILL GRADUALLY DIMINISH AS WEAK SFC HIGH PRES RIDGE MOVES FROM THE UPPER MISSISSIPPI VALLEY TOWARD THE UPPER LAKES. DGZ OCCUPIES A GOOD PORTION OF THE CONVECTIVE LAYER... SO MIGHT BE ABLE TO FLUFF UP SEVERAL INCHES OF SNOW ACCUMULATION THU. BEST ACCUMULATIONS SHOULD OCCUR IN FAR NRN ONTONAGON/CNTRL HOUGHTON COUNTIES DUE TO CONVERGENT WRLY FLOW INTO THAT AREA AND ALSO ERN ALGER/NRN LUCE COUNTIES WHERE MODELS DEPICT RATHER STRONG LOW-LEVEL CONVERGENCE. ADVY TYPE HEADLINE MAY BE REQUIRED FOR THE LATTER AREA. WITH PASSAGE OF SFC HIGH PRES RIDGE THU NIGHT...LINGERING LES WILL END AS WINDS SHIFT SW/OFFSHORE. FAVORED THE LOWER SIDE OF GUIDANCE FOR MIN TEMPS WITH AT LEAST A PERIOD OF LIGHT WINDS AND PARTLY CLOUDY SKIES IN MOST AREAS. WAA PATTERN WILL BE IN FULL SWING FRI AS PACIFIC AIR SPREADS OUT ACROSS THE NRN PLAINS IN DEVELOPING ZONAL FLOW. MIGHT BE A LITTLE PCPN ACROSS NRN UPPER MI...BUT BETTER PCPN POTENTIAL WILL BE FARTHER N WHERE SUFFICIENT LOW-LEVEL MOISTENING IS MORE LIKELY. TEMPS WILL REACH THE 20S ACROSS THE BOARD. WARMING WILL CONTINUE SAT AHEAD OF A SHORTWAVE TRACKING FROM BC/PACIFIC NW TO THE NRN PLAINS. MOST LOCATIONS SHOULD TOP OUT AROUND 30F. HOWEVER...A COLD FRONT DRIFTING S ACROSS UPPER MI WILL INFLUENCE MAX TEMPS DEPENDING ON ITS TIMING. UPPER DIVERGENCE ASSOCIATED WITH RIGHT ENTRANCE OF UPPER JET TO THE N AND NE SHOULD SUPPORT A RIBBON OF -SN BEHIND THE SOUTHWARD DRIFTING COLD FRONT. THAT -SN SHOULD BEGIN TO AFFECT NW UPPER MI SAT AFTN. AS COLD FRONT CONTINUES TO DROP S SAT NIGHT/SUN MORNING...EXPECT MOST OF THE FCST AREA TO SEE SOME -SN...AIDED BY RIGHT ENTRANCE UPPER DIVERGENCE. SOME LAKE ENHANCEMENT SEEMS LIKELY FOR MOST IF NOT ALL OF NRN UPPER MI AS WINDS WILL LIKELY SHIFT N FOR A TIME BEHIND COLD FRONT AND POTENTIAL WEAK SFC WAVE THAT WILL ALSO BE TRACKING ALONG FRONT. BEHIND THE COLD FRONT AND WITH THE PASSAGE OF ANOTHER SHORTWAVE ROTATING THRU THE UPPER LAKES AROUND EXPANDING POLAR VORTEX...MUCH COLDER AIR WILL DUMP INTO THE UPPER LAKES SAT NIGHT/SUN. THIS WILL RESULT IN NW FLOW LES TAKING OVER SUN AS 850MB TEMPS PLUMMET INTO THE LOW/MID -20S C. EXPECT SLOWLY FALLING TEMPS DURING THE DAY SUN. PERSISTENT LES WILL THEN SET UP MON/TUE...MOSTLY FOR W TO WNW WIND FAVORED SNOWBELTS...AS ACRTIC AIR SETTLES OVER THE AREA (850MB TEMPS IN THE MID -20S C). LES WILL THEN CONTINUE THRU THE END OF NEXT WEEK AS ARCTIC AIR WILL DOMINATE THE UPPER LAKES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1228 PM EST WED DEC 25 2013 CMX...EXPECT PREDOMINANT IFR CONDITIONS HERE WITH A W UPSLOPE FLOW TO GIVE WAY TO A PERIOD OF LOWER LIFR CONDITIONS TNGT WITH THE ARRIVAL OF A LO PRES TROF/WSHFT TO MORE WNW. ALTHOUGH CONDITIONS WL IMPROVE LATER TNGT/THU MRNG FOLLOWING THE EXIT OF THIS TROF...IFR VSBYS SHOULD PERSIST THRU 18Z THU WITH LK EFFECT -SHSN LINGERING. IWD...EXPECT MVFR TO VFR CONDITIONS THIS AFTN TO GIVE WAY TO A PERIOD OF IFR VSBYS TNGT WITH THE APRCH/PASSAGE OF A LO PRES TROF. FOLLOWING THE EXIT OF THIS TROF LATER TNGT...CONDITIONS WL IMPROVE TO MVFR AND THEN TO VFR ON THU WITH THE APRCH OF A HI PRES RDG/ BACKING LLVL FLOW. SAW...EXPECT VFR TO OCNL MVFR CONDITIONS THIS AFTN TO GIVE WAY TO A PERIOD OF MVFR CIGS TNGT ASSOCIATED WITH A LO PRES TROF PASSAGE. VFR WX SHOULD THEN FOLLOW LATE TNGT INTO THU WITH A DOWNSLOPE W WIND FOLLOWING THE TROF. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 531 AM EST WED DEC 25 2013 GALES EARLY TODAY FOR EASTERN PORTIONS OF LK SUPERIOR AS SOUTH WINDS ARE ENHANCED BY PRESSURE FALLS TO NORTH OF LK SUPERIOR. EXPECT WINDS TO DIMINISH TO LESS THAN 25 KTS LATER AFTN THROUGH TONIGHT. WINDS WILL DIMINISH FURTHER TO 10-20KT ACROSS MOST OF LAKE SUPERIOR THU/THU NIGHT AS A WEAK SFC HIGH PRES RIDGE PASSES. SW WINDS WILL THEN INCREASE TO 15-25KT FRI AHEAD OF THE NEXT APPROACHING COLD FRONT. AS THE FRONT DRIFTS S ACROSS THE AREA...WINDS WILL DIMINISH FRI NIGHT/SAT MORNING. ARCTIC AIR WILL THEN SURGE INTO THE UPPER LAKES LATE SAT THRU EARLY NEXT WEEK. MAY SEE SOME PERIODS OF GALES EARLY NEXT WEEK ALONG WITH THE RETURN OF HVY FREEZING SPRAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...KC SHORT TERM...JLA LONG TERM...ROLFSON AVIATION...KC MARINE...JLA/ROLFSON
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
1229 PM CST WED DEC 25 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 337 AM CST WED DEC 25 2013 TROUGHING AND CYCLONIC FLOW WILL DOMINATE THE SHORT TERM...WHICH MEANS LOTS OF CLOUDS AND BOUTS OF LIGHT SNOW WILL DOMINATE THE NEXT 24 HOURS. LOOKING AT WATER VAPOR IMAGERY OVERLAID WITH RAP H5 VORTICITY YOU CAN SEE A COUPLE OF WAVES UPSTREAM IN THE NW FLOW THAT WILL IMPACT US. THE FIRST IS CURRENTLY OVER ERN NODAK AND ALREADY HAS SNOW MOVING ACROSS ERN SODAK AND NW MN AND WILL BE ARRIVING IN THE MPX CWA SHORTLY. THE SECOND WAVE IS UP OVER NRN SASKATCHEWAN AND WILL BE WORKING ACROSS MN THIS AFTERNOON. THESE UPPER WAVES WILL BE WORKING WITH AN ELEVATED WARM FRONT IN THE H85-H7 LAYER TO THROW SEVERAL BOUTS OF LIGHT SNOW OUR DIRECTION THROUGH THE PERIOD. THE BEST BURST WILL BE THE INITIAL ONE THIS MORNING. THE HEAVIEST SNOW HAS BEEN ALONG THAT ELEVATED WARM FRONT OVER ERN SODAK OVERNIGHT AND FOLLOWED THE HRRR FOR BRINGING THIS SNOW DOWN THE MN RIVER THIS MORNING. HAVE ENOUGH QPF OUT OF IT TO GET 0.5 TO 1 INCH SNOW AMOUNTS FROM WC MN DOWN THE MN RIVER INTO SE MN. FOR THE REST OF THE PERIOD...THE PATTERN IN PLACE LEADS TO LOW CONFIDENCE ON WHEN/WHERE THESE LITTLE BURSTS OF SNOW WILL COME DOWN...SO THERE ARE LOTS OF SMALL POPS THROUGH 9Z TONIGHT...WHICH IS WHEN THE SREF AND HIRES MODELS FINALLY SHOW SNOW CHANCES EVACUATING THE MPX CWA...FOR A SHORT TIME ANYWAYS. TEMPERATURES WILL BE TRICKY THIS PERIOD AS WELL THANKS TO A SFC WARM FRONT THAT AT 3AM WAS NEAR A ROSEAU/LONG PRAIRIE/TWIN CITIES/ALBERT LEA LINE. TEMPERATURES EAST OF THIS BOUNDARY HAVE REMAINED IN THE SINGLE DIGITS...WITH TEMPERATURES SLOWLY RISING INTO THE TEENS AND EVEN LOWER 20S BY THE TIME YOU GET TO THE MN/SD BORDER. THE COLD FRONT WAS ALIGNED FROM A WEAK SFC LOW NEAR GRAND FORKS BACK NW INTO CENTRAL SASKATCHEWAN. THE WARM SECTOR ACROSS THE DAKOTAS HAS BEEN QUITE IMPRESSIVE THIS MORNING...WITH SEVERAL LOCATIONS ACROSS THE CENTRAL DAKOTAS WARMING TO BETWEEN 32 AND 34 DEGREES /ABOUT 35 DEGREES WARMER THAN THIS TIME 24 HOURS AGO!/. THE QUESTION FOR TODAY...IS HOW MUCH OF THIS WARM SECTOR CAN WE GET INTO THE MPX CWA. THE CORE OF THE WARMEST AIR LOOKS TO DROP SOUTHWEST OF THE MPX CWA...BUT WE SHOULD STILL SEE TEMPS RISE INTO THE UPPER 20S ACROSS WRN MN THIS MORNING...BEFORE THE COLD FRONT ARRIVES THIS AFTERNOON TO START SENDING TEMPERATURES THE OTHER DIRECTION. FOR TONIGHT THE TWO VARIABLES TO WATCH ARE WHAT HAPPENS WITH CLOUD COVER AND WHERE DOES THAT COLD FRONT END UP. AS FOR THE FRONT...MOST MODELS SHOW THE FRONT BECOMING STATIONARY ACROSS SW MN...WITH ANOTHER PUNCH OF ARCTIC AIR SLIDING DOWN ACROSS AREAS MAINLY NORTH OF I-94. THIS WILL KEEP TEMPERATURES TONIGHT IN THE MN RIVER VALLEY ON SOUTH UP IN THE TEENS...BUT BACK NORTH OF I-94...IF SKIES CAN STAY SUFFICIENTLY CLEAR...WE COULD SEE MORE WIDESPREAD DOUBLE DIGIT LOWS BELOW ZERO. IT/S NOT OUT OF THE REAL OF POSSIBILITY TO SEE A NEARLY A NEARLY 30 DEGREE SPREAD IN LOWS TONIGHT ACROSS THE MPX CWA...WITH LOWS AROUND 15 ABOVE OUT IN WRN MN AND AROUND 15 BELOW ALONG THE US-8 CORRIDOR IN WRN WI. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 337 AM CST WED DEC 25 2013 THE FORECAST WARM UP FOR THE LATER HALF OF THE WEEK STILL LOOKS TO BE ON SCHEDULE. SHOULD SEE MODERATING TEMPERATURES INTO SATURDAY WITH ANOTHER WAFT OF PACIFIC AIR MOVING THROUGH...AHEAD OF NEXT ARCTIC COLD FRONT. MODELS TREND ANOTHER SHOT OF SNOW ASSOCIATED WITH THE INITIAL PACIFIC AIR INTRUSION ON THURSDAY. AT THE MOMENT...HAVE INCLUDED A SMALL LIKELY POP AREA OVER THE NORTHEAST CWA. SIGNIFICANT MOISTURE APPEARS TO BE LACKING AND MOST MODELS HAVING TROUBLE SATURATING AS THE PRECIPITATION BAND MOVES FARTHER EAST. ANY SNOWFALL SHOULD REMAIN LIGHT FOR THIS SYSTEM. DO EXPECT SOME LOWER 30S AT LEAST AHEAD OF THE ARCTIC BOUNDARY AS THAT ARRIVES SATURDAY AFTERNOON. WITH STEEP LOW LEVEL LAPSE RATES...STRONG WIND GUSTS EXPECTED TO MATERIALIZE. 35 KT WIND GUSTS LOOK LIKELY AS THE SYSTEM MOVES THROUGH. THE BETTER CHANCE OF SNOW SHOWERS SHOULD RIDE FARTHER EAST...BUT IF THEY DO COINCIDE WITH THE STRONGEST WINDS...COULD SEE NEAR BLIZZARD CONDITIONS DEVELOP OVER THE SOUTHWEST/MINNESOTA RIVER VALLEY REGION SATURDAY AFTERNOON/EVENING. HAVE CONTINUED TO INCLUDE SOME BLOWING SNOW OVER THE REGION FOR THIS PERIOD...INTO SUNDAY. THE NEXT SURGE OF ARCTIC AIR DROPS OVER THE REGION SUNDAY AND LINGERS THROUGH MUCH OF THE COMING WEEK. NORTHWEST FLOW PATTERN WILL LEAVE THE REGION IN THE FAVORABLE AREA FOR MORE LIGHT/FLUFFY SNOW EVENTS. MONDAY NIGHT INTO TUESDAY NIGHT LOOKS LIKE THE NEXT BEST CHANCE OF SOME LIGHT SNOW. HAVE LOW POPS FOR NOW. WILL HOLD OFF ON HIGHER POPS FOR NOW...TO GET BETTER TIMING AS WE GET CLOSER TO THE EVENT. WIND CHILLS WILL ONCE AGAIN BECOME AN ISSUE AS THE COLD AIR ARRIVES AS WELL. THE 00Z ECMWF SHOWS LITTLE MODERATION IN TEMPERATURES IN THE LONGER TERM...WHICH WOULD TAKE US INTO THE FIRST WEEK OF THE NEW YEAR. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1220 PM CST WED DEC 25 2013 CONDITIONS ARE LARGELY IMPROVING ACROSS THE AREA WITH STEADY SNOW PUSHING EAST THROUGH WISCONSIN. GUSTY WINDS BEHIND A COLD FRONT HAS LED TO SOME BLOWING SNOW ACROSS WESTERN MN...WITH VSBYS IN THE MVFR CATEGORY. OTHERWISE...MVFR/VFR CIGS EXPECTED THROUGH TONIGHT. ANOTHER BATCH OF SNOW WILL SLIDE SOUTHEAST...MAINLY ALONG AND JUST NORTH OF THE MINNESOTA RIVER LATE THURSDAY MORNING. KMSP...MVFR CONDITIONS WILL BECOME MAINLY VFR THIS AFTERNOON...THEN BACK TO MVFR LATE THURSDAY MORNING WITH THE NEXT ROUND OF SNOW. /OUTLOOK FOR KMSP/ THU NIGHT...VFR. WINDS S AT 5 KTS. FRI...VFR. WINDS SW 5-10 KTS. SAT...VFR. CHC MVFR/-SN LATE. WINDS SW 5-10 KTS BCMG NW 20G30KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR MNZ041- 042-047>049-054>057-064-065-073>075-082-083-091-092. WI...NONE. && $$ SHORT TERM...MPG LONG TERM...DWE AVIATION...BORGHOFF
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1159 AM CST WED DEC 25 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 407 AM CST WED DEC 25 2013 WITH ESSENTIALLY ZERO RISK OF PRECIP THROUGH THE NEXT 24 HOURS...THE MAIN FORECAST ISSUES INVOLVE TEMPS/SKY COVER/AND HOW BREEZY IT WILL GET TODAY. TEMP-WISE...WHAT WOULD OTHERWISE BE A FAIRLY STRAIGHTFORWARD SITUATION IS COMPLICATED SOMEWHAT BY SOME MODELS/GUIDANCE STRUGGLING WITH THE INITIALIZATION OF EXISTING SNOW COVER. STARTING OFF EARLY THIS CHRISTMAS MORNING...ALL IS QUIET...AS THE LATEST 11-3.9 MICRON SATELLITE IMAGERY INDICATES ESSENTIALLY CLEAR SKIES CWA-WIDE...IN THE WAKE OF LOW STRATUS THAT HAS PUSHED EAST OF THE AREA...AND A BATCH OF MID LEVEL CLOUDS THAT HAS PUSHED SOUTH OF THE CWA. WATER VAPOR SATELLITE IMAGERY AND SHORT TERM MODEL DATA INDICATE A BROAD MID-UPPER TROUGH CENTERED OVER THE CENTRAL CONUS NORTHWARD INTO SOUTH CENTRAL CANADA...WHILE FARTHER WEST...A LARGE-SCALE RIDGE IS CENTERED OFF THE CA COAST IN THE PACIFIC. WITHIN THE LARGE SCALE TROUGH OVER THE LOCAL AREA...THERE ARE FEW SMALLER SCALE SHORTWAVE TROUGHS OF INTEREST...ONE OF WHICH IS CURRENTLY ORIENTED SOUTHWEST-NORTHEAST FROM SOUTHWEST KS- NORTHERN MO...AND IS EXITING THE SOUTHEAST CWA AT THIS TIME. MEANWHILE...ANOTHER CLIPPER-TYPE NORTHWEST-FLOW SHORTWAVE IS IN THE PROCESS OF DROPPING SOUTHWARD INTO THE DAKOTAS/MN...WITHIN THE EXIT REGION OF A STOUT 120+KT NORTHERLY JET STREAK EVIDENT AT 300 MILLIBARS THAT IS CURRENTLY POKING SOUTHWARD INTO MT OUT OF SASKATCHEWAN. AT THE SURFACE...09Z OBJECTIVE ANALYSIS AND AUTOMATED OBS REVEAL A FAIRLY UNIFORM FIELD OF WESTERLY BREEZES GENERALLY 5-10 MPH ACROSS THE CWA...DRIVEN WITHIN A FAIRLY WEAK PRESSURE GRADIENT BETWEEN A 1029MB HIGH CENTERED OVER THE NEB/CO BORDER AREA AND EXTENDING SOUTHEAST ACROSS KS...AND A 1015MB LOW CENTERED OVER NORTHWEST MN ASSOCIATED WITH THE AFOREMENTIONED CLIPPER. TEMP-WISE EARLY THIS MORNING...AS WESTERLY BREEZES HAVE BECOME MORE ESTABLISHED MOST PLACES HAVE LARGELY LEVELED OFF THE NOCTURNAL DROP OR EVEN RISEN SOMEWHAT FROM VALUES EARLIER IN THE NIGHT...BUT GIVEN THE CLEAR SKIES...SOME LOCALIZED DROPS ARE STILL LIKELY BEFORE THE NIGHT IS THROUGH. ACTUAL LOWS FOR THE NIGHT ALREADY HAVE BEEN...OR WILL EVENTUALLY BE...SOMEWHERE BETWEEN 15-21 ACROSS MOST OF THE CWA. FOR THE DAYTIME HOURS TODAY...THE MAIN STORY IN THE MID-UPPER LEVELS INVOLVES THE SOUTH-SOUTHEAST PROGRESSION OF THE AFOREMENTIONED CLIPPER SYSTEM...WHICH WILL MAINLY TAKE AIM ON THE MN/IA REGION AS THE MAIN VORTICITY MAXIMUM AT 500MB ENDS UP OVER NORTHERN MN BY 00Z/6PM TODAY. GIVEN THE TRACK OF THIS SYSTEM AND ITS FORCING FIELDS...ANY LIGHT PRECIP TODAY SHOULD MAINLY FOCUS ALONG A TRACK FROM EASTERN SD ACROSS SOUTHERN MN/NORTHERN IA...AND MAYBE AS FAR SOUTHWEST AS EXTREME NORTHEAST NEB. ALONG THESE SAME LINES...THE VAST MAJORITY OF THE CWA SHOULD SEE NOTHING MORE THAN LIMITED MID-HIGH CLOUD COVER TODAY...WITH SKIES AVERAGING OUT TO NO WORSE THAN MOSTLY SUNNY. THAT BEING SAID...MODELS SUCH AS THE 06Z NAM AND TO A GREATER EXTENT THE 08Z RAP 13 SHOW THAT THE SOUTHWEST EDGES OF WHAT COULD BE A FAIRLY SOLID BATCH OF LOWER STRATUS COULD COME VERY CLOSE TO INFILTRATING A FEW COUNTIES IN THE FAR NORTHEAST CWA SUCH AS NANCE/POLK...ALTHOUGH THE VAST MAJORITY OF THIS CLOUD MASS SHOULD PASS 50+ MILES EAST/NORTHEAST OF THE CWA. ALTHOUGH THE OFFICIAL FORECAST RUNS WITH THE ASSUMPTION THAT SKIES BECOME NO WORSE THAN PARTLY CLOUDY FOR A FEW HOURS IN THESE FAR NORTHEAST AREAS...THIS WILL BARE WATCHING AS THE RAP 900/850MB RELATIVE HUMIDITY FIELDS ARE CURRENTLY HANDLING UPSTREAM LOWER CLOUDS OVER NORTH CENTRAL/EASTERN SD PRETTY WELL. TURNING TO THE SURFACE SITUATION...THE MAIN FEATURE TODAY WILL BE SEVERAL HOURS OF INCREASED NORTHWEST BREEZES...AS ENHANCED LOWER LEVEL WINDS MIX DOWN TO THE SURFACE AS MIXING HEIGHTS INCREASE TO AROUND 875MB. THE PRIMARY PERIOD OF ENHANCED NORTHWEST BREEZES WILL FOCUS BETWEEN 15Z/9AM TO 22Z/4PM...WITH SUSTAINED SPEEDS 15-20 MPH AND GUSTS AT LEAST 20-25 MPH...AND GENERALLY STRONGEST ACROSS THE NORTHEAST 1/2 OF THE CWA. ALTHOUGH THIS NORTHWESTERLY WIND TECHNICALLY RESULTS IN AT LEAST WEAK COLD AIR ADVECTION ABOVE THE SURFACE EVIDENT AT 850MB...THE COMBINATION OF SUNSHINE AND DECENT MIXING SHOULD RESULT IN A CONSIDERABLY MILDER DAY...ESPECIALLY IN THOSE CENTRAL/EASTERN COUNTIES THAT REMAINED QUITE CLOUDY TUESDAY. AS HAS BEEN TYPICAL LATELY...TEMPERATURE FIELDS IN MODELS SUCH AS THE NAM12 AND ASSOCIATED GUIDANCE ARE HEAVILY CONTAMINATED BY OVER-ZEALOUS SNOW COVER INITIALIZATION. FORTUNATELY...THE HOURLY TEMP FIELD OF THE RAP13 LOOKED QUITE REASONABLE AND UNCONTAMINATED...AND THUS WAS FOLLOWED VERY CLOSELY TODAY. THIS RESULTED IN SIMILAR HIGH TEMPS TO PREVIOUS FORECAST...BUT 1-2 DEGREES WARMER IN MANY CENTRAL/SOUTHERN AREAS. THE NET RESULT IS A RANGE FROM UPPER 30S NORTH...LOW 40S CENTRAL AND MID 40S SOUTH...ALTHOUGH A RESPECTABLE 1-3 INCHES OF SNOW COVER CENTERED OVER MUCH OF FURNAS/GOSPER/HARLAN COUNTIES WILL LIKELY KEEP THOSE AREAS A BIT COOLER THAN BORDERING AREAS...GENERALLY UPPER 30S. TURNING TO THIS EVENING/TONIGHT...A RATHER QUIET AND PRECIP-FREE FORECAST CONTINUES. IN THE MID/UPPER LEVELS...MODEST HEIGHT RISES WILL BE EVIDENT AT 500MB OVER THE LOCAL AREAS...IN THE WAKE OF THE FAIRLY VIGOROUS CLIPPER SYSTEM DEPARTING EASTWARD INTO THE LOWER GREAT LEGION. MEANWHILE THOUGH...A WEAKER/MORE SUBTLE NORTHWEST- FLOW DISTURBANCE WILL GRADUALLY APPROACH THE CENTRAL PLAINS FROM THE NORTHERN ROCKIES...REACHING THE SD/NORTHWEST NEB AREA BY SUNRISE THURSDAY. LOCALLY...THE ONLY EFFECT OF THIS INCOMING WEAK WAVE WILL BE A MODEST INCREASE IN MAINLY HIGH LEVEL CLOUDS ESPECIALLY OVER NORTHERN ZONES...BUT EVEN SO...OVERNIGHT SKIES ARE FORECAST TO AVERAGE NO WORSE THAN MOSTLY CLEAR ACROSS THE MAJORITY OF THE CWA. AT THE SURFACE...WEAK PRESSURE FALLS CENTERED OVER THE DAKOTAS WILL ALLOW LOCAL BREEZES TO TRANSITION FROM NORTHWESTERLY THIS AFTERNOON TO A WEST-SOUTHWEST DIRECTION AT GENERALLY 5-10 MPH THROUGH THE OVERNIGHT HOURS. ALTHOUGH THESE WESTERLY BREEZES WILL INDUCE MODEST WARM AIR ADVECTION ALOFT EVIDENT AT 850MB...THE FAIRLY LIGHT SPEEDS WILL PROBABLY NOT BE ENOUGH TO OFFSET A DECENT TEMP DROP UNDER THE MOSTLY CLEAR SKIES. THUS TOOK A MIDDLE-GROUND APPROACH ON LOW TEMPS...MAKING VERY LITTLE CHANGE FROM PREVIOUS FORECAST VIA A MULTI-MODEL BLEND...RESULTING IN A FAIRLY UNIFORM LOW TEMPERATURE FIELD OF 16-20 ACROSS THE CWA. THIS IS GENERALLY 2-4 DEGREES MILDER THAN A BLEND OF 00Z MET/MAV GUIDANCE WHICH APPEARS TO BE A BIT TOO COLD...BUT IS NOT AS WARM AS RAW 2M TEMPS PRESENTED BY MODELS SUCH AS THE GFS/ECMWF. AS IS TYPICAL IN THESE OVERNIGHT WESTERLY WIND REGIMES THOUGH...THERE WILL LIKELY BE SCATTERED NON-DIURNAL TEMP TENDENCIES ACROSS PARTS OF THE AREA. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 407 AM CST WED DEC 25 2013 THURSDAY THROUGH NEW YEARS EVE DAY/TUESDAY. THE LATTER PART OF THE WEEK INTO THE FIRST PART OF THE WEEKEND ARE STILL SHAPING UP TO BE THE NICEST/WARMEST DAYS OF THE EXTENDED TIME FRAME. A NORTHWEST FLOW PATTERN WILL BE IN PLACE ACROSS OUR REGION WHILE THE UPPER TROUGH AND COLD AIR THROUGH THE OHIO VALLEY REGION LIFTS OUT ACROSS THE NORTHEAST CONUS. A WARMER AIRMASS WILL SETTLE IN FOR A FEW DAYS AND A DRY DOWNSLOPE WESTERLY WIND COMPONENT WILL AID IN THE TEMP WARMUP FOR OUR AREA. HIGH ON THURSDAY SHOULD AVERAGE IN THE LOW/MID 40S...WITH EVEN WARMER 50S EXPECTED FOR FRIDAY. TEMPERATURES ON SATURDAY WILL BE DEPENDENT UPON THE TIMING OF A STRONG COLD FRONTAL PASSAGE WHICH IS PROGGED TO CROSS OUR CWA DURING THE AFTN/EVENING. IF TIMING TRENDS FASTER...TEMPS WILL NOT BE AS WARM AS CURRENT FORECAST ESPECIALLY ACROSS OUR NORTHERN ZONES AND THERMAL GRADIENT WILL NEED TO BE TIGHTENED. THE 6HR PRESSURE RISES BEHIND FRONT AVERAGE 11MB AND EXPECT A PERIOD OF STRONG/GUSTY NORTH WINDS FOLLOWING FROPA AND HAVE RAMPED UP WIND SPEEDS HIGHER THAN WHAT INIT PROVIDED. MODELS ALSO SUGGEST LOW CLOUDS MOVING IN BEHIND BOUNDARY AND AS PREVIOUS DISCUSSION MENTIONED...COULD SEE SOME FLURRIES SATURDAY EVENING/NIGHT IN PRESENCE OF FRONTOGENESIS...AND IS SOMETHING TO MONITOR. A 1035MB SURFACE HIGH BUILDS SOUTH ONTO THE PLAINS SUNDAY BEHIND THE COLD FRONT AND TEMPERATURES WILL DROP BACK BELOW SEASONAL NORMALS FOR A COUPLE OF DAYS. THE AIRMASS LOOKS TO MODERATE SOME FROM LATE MONDAY INTO TUESDAY/NEW YEARS EVE DAY AND TEMPS NEAR NORMAL APPEAR REASONABLE FOR NOW. THIS BEING SAID...A COLD AIRMASS IS NOT THAT FAR AWAY AS A TROUGH DEEPENS OVER THE HUDSON BAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1147 AM CST WED DEC 25 2013 CLEAR TO MOSTLY CLEAR SKIES CAN BE EXPECTED THROUGH TONIGHT WITH PERHAPS INCREASING MID TO HIGH CLOUDS THURSDAY MORNING. HOWEVER...WILL NEED TO KEEP AN EYE ON A SCATTERED DECK OF MVFR CLOUDS WILL PASS JUST TO THE NORTHEAST OF KGRI THIS AFTERNOON. THE WIND WILL BE GUSTY AT TIMES THIS AFTERNOON...BUT WILL QUICKLY DIE OFF THIS EVENING. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...PFANNKUCH LONG TERM...FAY AVIATION...WESELY
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1039 AM CST WED DEC 25 2013 .UPDATE... MAIN CONCERN IN THE ONGOING TODAY PERIOD IS POPS/WX AS A SWATH OF LIGHT SNOW TAKES AIM AT THE CWA FROM SOUTHEAST MN AND NORTHERN IA. FORECAST WAS GENERALLY ON TRACK HOWEVER...DID UPDATE POPS/WX TO ACCOUNT FOR THE LATEST RADAR TRENDS. THE HRRR DOESNT SEEM TO BE HANDLING THE SWATH AS WELL COMPARED TO OUR LOCAL OFFICE WRF AND THE OTHER FLAVORS OF WRF AVAILABLE. THOUGH SAID WRF OUTPUT APPEARS TO BE A BIT SLOW. SNOW TO LIQUID RATIOS ARE EXPECTED TO BE AROUND 17:1 AT LEAST...SO THIS SHOULD YIELD ADDITIONAL ACCUMULATIONS OF AROUND AN HALF INCH TO AN INCH MOST PLACES. OTHERWISE...REST OF THE FORECAST PACKAGE WAS JUST ADJUSTED TO KEEP UP WITH TRENDS. && .AVIATION/18Z TAFS/... ON AND OFF LIGHT SNOW WILL CONTINUE THROUGH LATE MORNING...WITH VISIBILITIES GENERALLY RANGING FROM 3 TO 5 MILES. A MORE MODERATE SNOWFALL WILL MOVE IN WEST TO EAST FROM LATE MORNING AND INTO THE AFTERNOON...DROPPING A HALF AN INCH TO AN INCH MOST PLACES BY EARLY EVENING. COULD SEE VISIBILITIES DOWN TO 1 MILE FOR A TIME GIVEN UPSTREAM OBSERVATIONS. SNOW WILL EXIT THE EAST THIS EVENING...WITH DRY WEATHER EXPECTED OVERNIGHT. SHOULD SEE SKIES EVENTUALLY RETURN TO VFR BY LATE TONIGHT INTO THURSDAY MORNING. YET ANOTHER WEAK SYSTEM COULD BRING A LITTLE LIGHT SNOW BY LATE THURSDAY AFTERNOON. && .PREV DISCUSSION... /ISSUED 433 AM CST WED DEC 25 2013/ SHORT TERM... CHRISTMAS DAY AND TONIGHT - FORECAST CONFIDENCE HIGH IN SPITE OF DECENT FORCING...INTRUSION OF DRY AIR ABOVE 800 MB AND THROUGH THE DENDRITE GROWTH ZONE LIMITED AMOUNTS OF SNOW FROM INITIAL WARM ADVECTION BAND BUT SECOND BAND IS INTENSIFYING AS IT CROSSES EASTERN HALF OF WISCONSIN WITH ISENTROPIC ADIABATIC OMEGA INCREASING FROM 1.5 MICROBARS/SEC TO BETWEEN 2.5 AND 3.0 MICROBARS/SEC. WILL SEE BETWEEN 1/2 INCH AND 1 INCH OF ADDITIONAL ACCUMULATION FROM THIS BAND. A BREAK IN SNOW UNTIL NEXT SHORT WAVE DROPS INTO MN LATE THIS AFTERNOON... DOWN THROUGH WRN WI THIS EVENING AND ACROSS SRN WI/NRN IL OVERNIGHT. POTENT WAVE PRODUCING SUB-2 MILE VSBYS IN THE DAKOTAS. HAVE SPREAD CATEGORICAL POPS ACROSS THE CWA FROM WEST TO EAST FROM LATE THIS MORNING IN THE FAR WEST THROUGH THE AFTERNOON. LINGERED POPS IN THE EAST THIS EVENING WITH DIFFERENTIAL CYCLONIC VORTICITY ADVECTION ACTING ON A COLUMN STILL MOIST UP THROUGH DENDRITE GROWTH ZONE UNTIL AROUND 03Z. HIGH TEMPERATURES IN THE LOWER TO MID 20S TODAY WITH 925MB-850MB THERMAL RIDGES PASSING THROUGH. TEMPS FALL TONIGHT WITH LOWS IN THE SINGLE DIGITS BY THURSDAY MORNING WITH 925 MB TEMPS DROPPING INTO THE TEENS BELOW ZERO BY 12Z. THURSDAY-FORECAST CONFIDENCE HIGH DEEP TROUGH MOVES EAST OF AREA WITH SIGNIFICANT 500 MB HEIGHT RISES ON THE ORDER OF 160 METERS IN THE MORNING OVER SOUTHERN WISCONSIN. EMBEDDED WITHIN FAST NORTHWEST FLOW WILL BE ANOTHER WEAK SHORT WAVE TROUGH THAT WILL MOVE ACROSS THE DAKOTAS AND MINNESOTA AND INTO WISCONSIN BY THE AFTERNOON. GFS AND ECMWF ARE IN PRETTY GOOD AGREEMENT WITH BAND OF LIGHT SNOW WITH THIS...BUT NAM IS RATHER DRY. LEANED TOWARD FORMER SOLUTION AND WENT WITH CHANCE POPS. ALTHOUGH 1000-500 MB THICKNESS VALUES INCREASE ABOUT 100 METERS IN A 24 HOUR PERIOD...THE LOW LEVEL THERMAL FIELD DOESN`T CHANGE MUCH SO ONLY MINOR MODERATION EXPECTED WITH HIGHS STILL 5 TO 10 DEGREES BELOW NORMAL. FRIDAY-FORECAST CONFIDENCE HIGH MILD SOUTHWEST FLOW REGIME EXPECTED WITH HEIGHTS RISING ANOTHER 70 METERS AND TEMPERATURES CLIMBING TO ABOUT NORMAL FOR LATE DECEMBER. AIRMASS LOOKS RATHER DRY. TEMPERATURES HOLDING STEADY OR RISING IN WARM ADVECTION PATTERN WITH SOUTHWEST FLOW AT NIGHT. LONG TERM... SATURDAY-FORECAST CONFIDENCE HIGH UPPER FLOW TILTS FROM WEST-NORTHWEST TO WESTERLY AS A TROUGH DIGS INTO NORTHERN PLAINS. FRONT STAYS WELL NORTH OF THE AREA DURING THE DAY ALLOWING MILD AIRMASS TO OVERSPREAD SOUTHERN WISCONSIN. THIS AIRMASS WILL BE RATHER DRY...LIMITING THE POTENTIAL FOR PRECIPITATION AND ADVECTION FOG. LOOKS LIKE ABOVE FREEZING HIGHS IN THE MIDDLE 30S A GOOD BET DESPITE THE DEEP SNOW COVER WITH 850 MB TEMPS ABOVE +6C. PARTY IS OVER AT NIGHT AS COLD FRONT SURGES THROUGH ALONG WITH 120 METER 500 MB HEIGHT FALLS. LOOKS LIKE 850 MB TEMPS CRASH ABOUT 15C OVERNIGHT. POTENTIAL FOR POST FRONTAL FREEZING RAIN GOING OVER TO SNOW ESPECIALLY NORTH LATER ON. SUNDAY-FORECAST CONFIDENCE HIGH STRONG COLD ADVECTION WITH LIKELY RESULT IN FALLING TEMPERATURES DURING THE DAY FROM THE TEENS INTO THE SINGLE DIGITS WITH A CHANCE OF LIGHT SNOW CONTINUING ESPECIALLY EAST. WIND CHILL VALUES CURRENTLY FORECAST TO DROP INTO -20 TO -30 RANGE SUNDAY NIGHT SO MAY NEED WIND CHILL HEADLINES LATER ON. MONDAY-FORECAST CONFIDENCE HIGH HEIGHTS AND THICKNESS JUST KEEP FALLING AS -45C 500 MB COLD CORE MOVES ACROSS ONTARIO WITH 1000-500 MB THICKNESSES DOWN AROUND 5000 METERS OVER SOUTHERN WISCONSIN. TEMPERATURES START OUT AROUND 10 BELOW ZERO INLAND AND STRUGGLE INTO SINGLE DIGITS ABOVE ZERO DURING THE DAY WITH WIND CHILLS ONLY ABOUT 10 BELOW ZERO. WINDS WILL DROP OFF DURING THE AFTERNOON AS THE POLAR HIGH MOVES OVERHEAD. LOOKS LIKE WELL BELOW ZERO AGAIN AT NIGHT WITH BETTER RADIATION CONDITIONS WITH LOWS OF 10 TO 15 BELOW OR COLDER IN THE WIND SHELTERED LOCATIONS. TUESDAY-FORECAST CONFIDENCE MEDIUM ALTHOUGH GFS IS ABOUT 6 HOURS FASTER AS IS TYPICAL VERSUS ECMWF...BOTH MODELS BRING A RATHER SIGNIFICANT ALBERTA CLIPPER ACROSS IOWA INTO NORTHERN ILLINOIS. VERY COLD AIRMASS AND POTENTIAL LAKE ENHANCEMENT SITUATION WITH ECMWF SHOWING ABOUT A THIRD OF AN INCH OF LIQUID. SO THIS COULD END UP BEING AN ADVISORY TYPE SNOW EVENT. --SPECIAL NOTE ABOUT DAYS 8 TO 11-- ALTHOUGH BEYOND THE FORECAST PERIOD...THE 00Z ECMWF HAS MASSIVE HEIGHT FALLS IN A HIGH AMPLITUDE PATTERN OVER THE GREAT LAKES LATER IN THE WEEK. A SIGNIFICANT COLD WAVE ACCOMPANIED BY BITTER WINDS IS A POSSIBILITY. AVIATION/12Z TAFS/... MVFR/BRIEFLY IFR VSBYS WITH LAST OF THE MODERATE SNOW BAND EXPECTED TO PUSH OUT OVER LAKE MICHIGAN BY 12Z. STRATUS DECK TO THE WEST ALL THE WAY BACK TO WESTERN MN AND IA LEADS TO PESSIMISTIC SKY FORECAST WITH MVFR CIGS EXPECTED THROUGH THE DAY. CURRENT TIMING OF SNOW WITH NEXT WAVE BRINGS MVFR/BRIEF IFR VSBYS TO KMSN BETWEEN 17Z AND 18Z...KUES AROUND 19Z AND TO KMKE AND KENW BETWEEN 1930Z AND 20Z. LOOKING AT A 3-4 HOUR PERIOD OF STEADY LIGHT...TO AT TIMES MODERATE...SNOW WITH UP TO ANOTHER INCH OF SNOW BY EVENING IN SOME LOCATIONS. LINGERING LIGHT SNOW UNTIL 03Z AT EASTERN TAF SITES. MARINE... WILL KEEP CURRENT END TIME OF SMALL CRAFT ADVISORY AT 00Z AS APPROACHING TROUGH WILL LOWER SOUTHWEST WINDS THIS AFTERNOON...THEN BACK WINDS TO THE WEST WITH TROUGH PASSAGE EARLY THIS EVENING AND FURTHER EASE TO 10 TO 15 KNOTS. WAVES WILL SLOWLY SUBSIDE DURING THE DAY WITH THE DEVELOPING OFFSHORE FETCH AND LOWERING WIND SPEEDS. WINDS AND WAVES STILL LOOK TO BE BELOW CRITERIA BY EARLY THIS EVENING. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS EVENING FOR LMZ643>646. && $$ UPDATE...ET/DDV TODAY/TONIGHT AND AVIATION/MARINE...REM THURSDAY THROUGH TUESDAY...CRAVEN