Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/23/13


AREA FORECAST DISCUSSION
NWS PUEBLO CO
250 PM MST SAT DEC 21 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 250 PM MST SAT DEC 21 2013 UPPER LOW IS LIFTING OUT INTO WESTERN OK WHILE TRAILING ENERGY IS DROPPING ACROSS THE FORECAST AREA IN NW FLOW ALOFT. PRECIPITATION HAS BEEN SLOW TO GET GOING ACROSS THE FORECAST AREA...THOUGH WEB CAMS AND SURFACE OBS ALONG THE CONTDVD HAVE BEEN REPORTING SOME SNOW THROUGH THE DAY. INITIALLY HEAVIEST SNOW AND BEST LIFT WILL BE OUT ACROSS THE FAR SOUTHEAST CORNER OF THE FORECAST AREA WHERE WRAP AROUND PRECIPITATION CONTINUES ACROSS BACA COUNTY. STILL SOME VARIABILITY IN THE SHORT RANGE MODELS FOR SNOW AMOUNTS OUT THAT WAY...BUT AN INCH OR TWO WOULD`T BE OUT OF THE QUESTION ACROSS SOUTHEAST PORTIONS OF BACA COUNTY. MEANWHILE...SHOULD START TO SEE LIGHT SNOW RAMP UP ACROSS THE EASTERN MOUNTAINS AND ADJACENT PLAINS BY 4 PM...WHICH WILL SPREAD SOUTH AND EAST THROUGH THE EVENING. NAM12 AND HRRR SEEM TO BE BACKING OFF ON SNOWFALL AMOUNTS WITH EACH RUN...WITH NAM12 NOW SHOWING AROUND 2-4 INCHES FOR THE SE MTS. HAVE KEPT SNOW AMOUNTS IN THE 2-6 INCH RANGE AS SUSPECT THERE WILL BE POCKETS OF HEAVIER AMOUNTS...HOWEVER WITHOUT A PERSISTENT DEEP NE UPSLOPE FLOW...THINK THESE HEAVIER AMOUNTS WILL BE MORE LOCALIZED. THUS ADVISORIES DO NOT SEEM WARRANTED AT THIS POINT. LIGHT SNOW WILL WIND DOWN TOWARDS TOMORROW MORNING WITH PARTIAL CLEARING ACROSS WESTERN AND NORTHERN PORTIONS OF THE AREA TOWARDS DAWN. THIS OPENS UP THE POSSIBILITY FOR ANOTHER ROUND OF GROUND FOG AT KALS EARLY SUNDAY MORNING...AND HAVE INTRODUCED THIS TO THE GRIDS. QUIET WEATHER FOR SUNDAY...THOUGH NORTHWEST FLOW MAY KEEP SOME SCATTERED OROGRAPHIC SNOW SHOWERS CONTINUING ACROSS THE CENTRAL MTS. TEMPERATURES TOMORROW MAY END UP SIMILAR TO THOSE OF TODAY...PERHAPS A LITTLE WARMER ACROSS PORTIONS OF THE PLAINS AND A TAD COOLER ACROSS THE MTS WHERE H7 TEMPS WILL BE A LITTLE COOLER BEHIND THIS EVENINGS SYSTEM. -KT .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 250 PM MST SAT DEC 21 2013 SUNDAY NIGHT-MONDAY...STRONG NORTH TO NORTHWEST FLOW ALOFT ACROSS THE REGION SUNDAY NIGHT SLOWLY MODERATES THROUGH THE DAY MONDAY...AS A BROAD UPPER TROUGH AND ASSOCIATED 120KT JET CORE ACROSS THE NORTHERN ROCKIES TRANSLATES OUT ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS. NORTHWEST FLOW ALOFT BEHIND THE SYSTEM LOOKS TO KEEP GENERALLY LIGHT SNOWFALL IN PLACE ACROSS THE CENTRAL MTS THROUGH EARLY MONDAY MORNING...WITH ACCUMULATIONS OF A FEW INCHES POSSIBLE ESPECIALLY NORTH OF COTTONWOOD PASS. PASSING SYSTEM STAYS TOO FAR NORTH AND EAST TO BRING PRECIPITATION TO THE REST OF SOUTH CENTRAL AND SOUTHEAST COLORADO...THOUGH DOES SEND A WEAK COLD FRONT ACROSS THE FAR EASTERN PLAINS EARLY MONDAY MORNING...KEEPING THE COOLEST TEMPERATURES OUT NEAR THE KANSAS BORDER. MONDAY NIGHT-CHRISTMAS DAY...LATEST MODELS CONTINUE TO DOWNPLAY SNOWFALL ACROSS THE AREA FOR CHRISTMAS EVE AND EARLY CHRISTMAS DAY WITH MODERATE NORTHWEST FLOW ALOFT ACROSS THE STATE AS ANOTHER UPPER TROUGH TRANSLATES ACROSS THE NORTHERN ROCKIES. THE 12Z ECMWF IS STILL A TAD DEEPER WITH SAID SYSTEM AND CONTINUES TO PRINT OUT SOME QPF ACROSS THE EASTERN MTS TUESDAY NIGHT...THOUGH WITH ITS H7 FLOW PROGGED TO REMAIN NORTH TO NORTHWEST...ANY SNOW WOULD GENERALLY REMAIN SOUTH OF HIGHWAY 50 ACROSS THE SOUTHERN I-25 CORRIDOR. AT ANY RATE...MODEL CONSENSUS KEEPS SLIGHT POPS ACROSS THE HIGHER TERRAIN AS WELL AS ALONG THE PALMER DVD AND RATON MESA FOR LATE TUESDAY AFTERNOON THROUGH EARLY WEDNESDAY MORNING AND HAVE STAYED THE COURSE FOR NOW. AS FOR TEMPS...WESTERLY FLOW AHEAD OF SAID SYSTEM LOOKS TO KEEP BREEZY WINDS AND WARMING TEMPERATURES ACROSS THE STATE MONDAY NIGHT AND TUESDAY...WITH ANOTHER WEAK COLD FRONT MOVING ACROSS THE PLAINS CHRISTMAS EVE HELPING TO COOL HIGHS TO NEAR SEASONAL AVERAGES FOR CHRISTMAS DAY. WEDNESDAY NIGHT-SATURDAY...MODERATE NORTHWEST FLOW PROGGED ACROSS THE REGION THROUGH THE REST OF THE EXTENDED PERIOD WITH A FEW MINOR DISTURBANCES MOVING THROUGH THE FLOW ACROSS THE NORTHERN ROCKIES AND INTO THE NORTHERN HIGH PLAINS. THIS WILL KEEP THE AREA GENERALLY WARM AND DRY...SAVE A FEW OCCASIONAL FLURRIES ACROSS THE HIGHER TERRAIN OF THE CENTRAL MTS...AS TEMPERATURES WARM BACK TO ABOVE SEASONAL LEVELS THROUGH THE PERIOD. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 250 PM MST SAT DEC 21 2013 SNOW SHOWERS WILL CONTINUE TO DEVELOP AND SPREAD TO THE SOUTHEAST ACROSS THE AREA THROUGH THE LATE AFTERNOON AND EARLY EVENING. STILL APPEARS THAT KCOS AND KALS MAY SEE PASSING -SHSN THIS EVENING...WITH SOME BRIEF MVFR CIGS/VIS. LOWER CIGS/VIS WILL LIKELY OCCUR ACROSS THE SE MTS...WITH IFR TO LIFR CONDITIONS AT TIMES. KPUB WILL HAVE THE LEAST THREAT OF BEING IMPACTED BY SNOW...SO HAVE KEPT CIGS PRIMARILY VFR. AS FOR SNOWFALL...SHOULD SEE LESS THAN AN INCH AT THE KCOS AND KALS TERMINALS. -SHSN WILL TAPER OFF FROM NORTHWEST TO SOUTHEAST OVERNIGHT...WITH IMPROVING CONDITIONS AT THE KCOS AND KPUB TAF SITES. WITH CLEARING SKIES OVERNIGHT...KALS MAY SEE A RETURN OF IFR TO LIFR CIGS/VIS WITH PATCHY GROUND FOG SUNDAY MORNING AND HAVE PUT THIS IN THE TAF BETWEEN 12Z AND 16Z. VFR CONDITIONS WILL RETURN FOR MOST OF THE REGION ON SUNDAY. THE EXCEPTION WILL BE SOME MVFR TO IFR CIGS AT TIMES ACROSS THE CENTRAL MOUNTAINS WHERE SCATTERED LIGHT OROGRAPHIC SNOW SHOWERS WILL CONTINUE. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...KT LONG TERM...MW AVIATION...KT
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1238 PM MST SAT DEC 21 2013 .UPDATE...BASED ON LATEST RADAR TRENDS...BAND OF SNOW IS SHIFTING SOUTHWARD AND AIRMASS IS SATURATING WITH LIGHT SNOW MOVING INTO FORT COLLINS. THIS WILL CONTINUE TO SPREAD SOUTHWARD THROUGH THE REST OF THE AFTERNOON...SO HAVE FURTHER INCREASED POPS IN/NEAR THE FOOTHILLS. EARLIER ARRIVAL LOOKS LIKE AN EARLIER DEPARTURE AS WELL...WITH MOST SNOW IN THE LOWER ELEVATIONS OVER BY MIDNIGHT. && .AVIATION...MOVED UP TIMING OF SNOW BASED ON LATEST RADAR TRENDS. SHOULD REACH KBJC BY 22Z AND KDEN BY 23Z-00Z. && .PREV DISCUSSION... /ISSUED 1108 AM MST SAT DEC 21 2013/ UPDATE...BAND OF MID LEVEL MOISTURE AND LIGHT SNOW WAS CURRENTLY SPREADING ACROSS THE MOUNTAINS AND FAR NORTHER BORDER AREA. MOST OF THIS IS VIRGA ON THE PLAINS RIGHT NOW...BUT CONTINUED WEAK LIFT AND WEAK ANTICYCLONIC UPSLOPE FLOW SHOULD EVENTUALLY SATURATE THE LOWER LEVELS LATER THIS AFTERNOON INTO THE EVENING. GIVEN CURRENT RADAR TRENDS AND SHORT RANGE MODEL GUIDANCE...HAVE INCREASED THE AFTERNOON POPS IN/NEAR THE FOOTHILLS. LATEST RAP RUNS SEEM TO GET A LITTLE TOO EXCITED ABOUT SNOW AMOUNTS AGAINST THE FRONT RANGE THIS EVENING...BUT THERE IS SOME LOW/MID LEVEL INSTABILITY SO WILL CONTINUE TO MONITOR POTENTIAL SNOW ACCUMULATIONS. AT THIS TIME...STILL LOOKING LIKE MOST PLAINS LOCATIONS SHOULD BE AN INCH OR LESS. IN THE MOUNTAINS...OROGRAPHIC HELP WILL LIKELY PROVIDE LOW END ADVISORY AMOUNTS THROUGH SUNDAY MORNING. AVIATION...FOG IS FINALLY LIFTING AT KDEN...ONE OF THE LAST PLACES TO CLEAR. NEXT WEATHER CONCERN IS SNOW AS ECHOES ALREADY FILLING IN NEAR THE WYOMING BORDER. THESE WILL ADVANCE SLOWLY SOUTHWARD WITH A LOWERING OF THE CLOUD DECK AND EXPECTED ILS LANDING CONDITIONS DEVELOPING BY 21Z-22Z. LATEST TRENDS SEEM TO BE A LITTLE FASTER SO THERE IS ALSO A CHANCE OF LIGHT SNOW DEVELOPING AS EARLY AS 22Z...BUT MAIN THREAT OF SNOW AND IFR CONDITIONS IS 00Z-08Z. ACCUMULATIONS AT THE FRONT RANGE AIRPORTS MOST LIKELY AN INCH OR LESS...AND KDEN WILL LIKELY BE ON THE EDGE OF THE ACCUMULATING SNOW. PREV DISCUSSION... /ISSUED 824 AM MST SAT DEC 21 2013/ AVIATION...DENSE FOG AT KDEN WITH RVRS MAINLY BELOW 1000 FT. THE FOG HAS LIFTED AT KBJC WITH ONLY LIGHT FOG AT KAPA...AND EROSION SHOULD CONTINUE FROM THE WEST/WEST-SOUTHWEST AS SURFACE WINDS ARE TRENDING THAT WAY. EXACT TIMING OF DISSIPATION AT KDEN IS DIFFICULT DUE TO HIGH CLOUDS MOVING OVER THE TOP...BUT AT THIS TIME EXPECT SOME IMPROVEMENT STARTING 16Z AND TOTAL EROSION EXPECTED BY 17Z-18Z. WILL CONTINUE TO MONITOR. PREV DISCUSSION... /ISSUED 528 AM MST SAT DEC 21 2013/ UPDATE... SHORT TERM...AREAS OF DENSE FOG HAVE EXPANDED THE PAST HOUR SO HAVE ISSUED AN ADVISORY BOUNDED BY A FORT COLLINS TO GREELEY TO FORT MORGAN TO DENVER LINE. AVIATION...WEAK DENVER CYCLONE WITH LIGHT NW WINDS HAS ALLOWED DENSE FOG OVER WELD COUNTY TO EXPAND SOUTHWARD INTO THE DENVER AREA. EXPECT THESE CONDITIONS WILL CONTINUE THROUGH 16Z. PREV DISCUSSION... /ISSUED 330 AM MST SAT DEC 21 2013/ SHORT TERM...SOME LOCALIZED FOG EARLY THIS MORNING EXTENDED FM FORT COLLINS TOWARDS FORT MORGAN AS SHOWN BY CIRA IMAGERY BUT SHOULD BURN OFF BY MID MORNING. OVERALL WILL CONTINUE TO SEE NW FLOW ALOFT THRU TONIGHT AS A FEW WEAK DISTURBANCES TRACK ACROSS NRN CO MAINLY TONIGHT. CROSS-SECTIONS SHOW MOISTURE WILL INCREASE IN THE MTNS BY THIS AFTN AND CONTINUE OVERNIGHT WITH FAVORABLE OROGRAPHICS AND LAPSE RATES AROUND 7 C/KM. THUS SNOW SHOULD INCREASE THIS AFTN AND CONTINUE OVERNIGHT SO WILL ISSUE A WINTER WEATHER WINTER ADVISORY WHICH WILL LINGER THRU MIDDAY SUN. OTHERWISE OVER NERN CO IT SHOULD BE DRY THRU THE AFTN ALTHOUGH COULD SEE A FEW LIGHT SNOW SHOWERS DEVELOP NR THE WY BORDER AND OVER THE PALMER DIVIDE LATE. HIGHS THIS AFTN WILL BE IN THE 30S OVER THE PLAINS. BY THIS EVENING A SURGE OF COOLER AIR WILL MOVE INTO NERN CO AND ENHANCE UPSLOPE FLOW ALONG THE FRONT RANGE. CROSS-SECTIONS SHOW INCREASING MOISTURE BEHIND THIS FNT AND AS WK DISTURBANCE MOVES ACROSS THIS EVENING SHOULD SEE A PERIOD OF LIGHT SNOW MAINLY IN AND NEAR THE FOOTHILLS. AT THIS TIME ACCUMULATIONS SHOULD BE ONLY AN INCH OR TWO. BY LATE TONIGHT THE UPSLOPE FLOW WILL GRADUALLY WEAKEN AFTER MIDNIGHT SO SNOW SHOULD GRADUALLY END BY 09Z OR SO. LONG TERM...BLOCKING MULTI-LEVEL HIGH PRESSURE RIDGE PRESENTLY OFF THE WEST COAST OF NORTH AMERICA SHOWS LITTLE SIGNS OF MOVEMENT DURING THE UPCOMING WEEK ACCORDING TO SHORT AND MEDIUM RANGE MODELS. AS A CONSEQUENCE COLORADO WILL REMAIN UNDER MODERATELY STRONG NORTHWEST FLOW DURING THE TIME PERIOD. MODELS SHOW A SERIES OF SUBTLE UNDULATIONS IN THIS FLOW ROUNDING THE TOP OF THE RIDGE AND PASSING OVER COLORADO...THE FIRST EXITING THE AREA SUNDAY MORNING...ANOTHER PASSING BY SUNDAY EVENING...AND YET ANOTHER PASSING THROUGH TUESDAY AFTERNOON AND/OR EVENING. RELYING ON THE MODELS TO RESOLVE THESE WEAK PERTABATIONS AND THEIR SPEED OF MOTION IN THIS FAST FLOW IS ASKING FOR DISAPPOINTMENT. THE SUNDAY EVENING SYSTEM APPEARS TO HAVE THE BEST POTENTIAL FOR PRODUCING SNOWFALL IN THE HIGH COUNTRY AND FOR PARTS OF NORTHEAST COLORADO. GFS IS THE MOST OPTIMISTIC OF THE MODELS WITH SNOW CHANCES ON THE PLAINS. HOWEVER THE NAM...GFS...ECMWF AND CANADIAN MODELS ALL INDICATE THE PRESENCE OF THIS WAVE OVER NORTHEAST COLORADO SUNDAY EVENING AND AT LEAST MIMINAL AMOUNTS OF QPF ACROSS THE NORTHEAST CORNER OF THE STATE. SURROUNDING WFOS CONCUR AND SO HAVE UPPED POPS TO 30-40 PCT IN ZONES ACROSS THE NORTHEAST CORNER SUNDAY EVENING. SHOULD THEN SEE PRECIP/SNOW CHANCES FALL OFF AFTER 07Z WITH THE JET LEVEL FORCING ALOFT EXITING THE AREA. ANY SNOW ACCUMULATION SHOULD BE MINIMAL. MEANWHILE MOUNTAINS AND HIGH VALLEYS HAVE A REASONABLE CHANCE OF MEASURING SNOWFALL WITH THIS SYSTEM. FOR NOW...WILL GO WITH 40-60 PCT POPS IN THE MTN ZONES AND 30-40 PCT POPS IN NORTH AND MIDDLE PARKS...ZONE 30 AND 32. SEE LITTLE IF ANY CHANCE OF SNOW FOR SOUTH PARK ZONE 37 AS NORTHWEST FLOW NOT CONDUCIVE FOR SNOWFALL HERE. COULD SEE A COUPLE INCHES OF SNOW ON THE NORTHERN MTN RIDGES AND HIGH PASSES BY MONDAY MORNING. NOT EXPECTING ANY SNOW IN THE I-25 URBAN CORRIDOR... EXCEPT PERHAPS A DUSTING UP NEAR THE WYOMING BORDER. THE LAST OF THESE WAVES IS PREDICTED BY THE EUROPEAN MODEL TO PASS OVER NORTHEAST COLORADO TUESDAY EVENING. WHEREAS THE GFS MODEL BARELY SHOWS A WAVE AND HARDLY ANY MOISTURE. HOWEVER...BOTH MODELS SHOW A WEAK COLD FRONT SLIPPING SOUTH ACROSS NORTHEAST COLORADO DURING THE AFTERNOON USHERING IN COLDER TEMPERATURES FOR TUESDAY NIGHT AND WEDNESDAY/CHRISTMAS DAY. SO FOR NOW...WILL HANG ONTO LOW POPS FOR TUESDAY EVENING IN THE MTNS...FOOTHILLS AND ALONG THE PALMER DIVIDE JUST IN CASE THE ECMWF IS CORRECT. WEDNESDAY AND BEYOND...A DRY AND COOL NORTHWEST FLOW REMAINS IN PLACE THROUGH THE END OF THE WEEK WITH A UPPER RIDGE STILL OFF THE WEST COAST. MODELS HINT AT THE PASSAGE OF YET ANOTHER SHORT WAVE DISTURBANCE EITHER THURSDAY AFTERNOON OR NIGHT. BUT CONFIDENCE IS LOW IN THE MODELS THAT FAR OUT. SO WILL KEEP THINGS DRY AND TEMPERATURES NEAR TO SLIGHTLY ABOVE AVERAGE THURSDAY AND FRIDAY. AVIATION...WINDS WERE SE EARLY THIS MORNING WITH CIRA IMAGERY SHOWING FOG CONFINED TO AREAS AROUND FORT COLLINS TO GREELEY. THE HRRR KEEPS THIS FOG AND LOW CLOUDS OVER WELD COUNTY THROUGH THE MORNING HOURS. HOWEVER THE RAP SHOWS A WEAK DENVER CYCLONE DEVELOPING WITH WINDS BECOMING LIGHT NNW BY SUNRISE WITH THE POTENTIAL FOR FOG AND LOW CLOUDS WHICH WOULD LINGER THRU THE LATE MORNING HOURS OVER DIA. AT THIS POINT WILL HAVE TO MONITOR TRENDS THE NEXT FEW HOURS AND SEE HOW THINGS DEVELOP. FOR TONIGHT A SURGE OF COOLER AIR WILL AFFECT THE AREA BEHIND A FNT WITH UPSLOPE FLOW DEVELOPING. AT THIS TIME MAY SEE A PERIOD OF LIGHT SNOW ESPECIALLY IN THE 02Z-08Z TIMEFRAME WITH UP TO AN INCH OF ACCUMULATION POSSIBLE. THE SNOW THREAT SHOULD END BY 09Z OR SO WITH IMPROVING CONDITIONS. && .BOU WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL NOON MST SUNDAY FOR COZ031-033-034. && $$ SHORT TERM...BARJENBRUCH LONG TERM....BAKER AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1108 AM MST SAT DEC 21 2013 .UPDATE...BAND OF MID LEVEL MOISTURE AND LIGHT SNOW WAS CURRENTLY SPREADING ACROSS THE MOUNTAINS AND FAR NORTHER BORDER AREA. MOST OF THIS IS VIRGA ON THE PLAINS RIGHT NOW...BUT CONTINUED WEAK LIFT AND WEAK ANTICYCLONIC UPSLOPE FLOW SHOULD EVENTUALLY SATURATE THE LOWER LEVELS LATER THIS AFTERNOON INTO THE EVENING. GIVEN CURRENT RADAR TRENDS AND SHORT RANGE MODEL GUIDANCE...HAVE INCREASED THE AFTERNOON POPS IN/NEAR THE FOOTHILLS. LATEST RAP RUNS SEEM TO GET A LITTLE TOO EXCITED ABOUT SNOW AMOUNTS AGAINST THE FRONT RANGE THIS EVENING...BUT THERE IS SOME LOW/MID LEVEL INSTABILITY SO WILL CONTINUE TO MONITOR POTENTIAL SNOW ACCUMULATIONS. AT THIS TIME...STILL LOOKING LIKE MOST PLAINS LOCATIONS SHOULD BE AN INCH OR LESS. IN THE MOUNTAINS...OROGRAPHIC HELP WILL LIKELY PROVIDE LOW END ADVISORY AMOUNTS THROUGH SUNDAY MORNING. && .AVIATION...FOG IS FINALLY LIFTING AT KDEN...ONE OF THE LAST PLACES TO CLEAR. NEXT WEATHER CONCERN IS SNOW AS ECHOES ALREADY FILLING IN NEAR THE WYOMING BORDER. THESE WILL ADVANCE SLOWLY SOUTHWARD WITH A LOWERING OF THE CLOUD DECK AND EXPECTED ILS LANDING CONDITIONS DEVELOPING BY 21Z-22Z. LATEST TRENDS SEEM TO BE A LITTLE FASTER SO THERE IS ALSO A CHANCE OF LIGHT SNOW DEVELOPING AS EARLY AS 22Z...BUT MAIN THREAT OF SNOW AND IFR CONDITIONS IS 00Z-08Z. ACCUMULATIONS AT THE FRONT RANGE AIRPORTS MOST LIKELY AN INCH OR LESS...AND KDEN WILL LIKELY BE ON THE EDGE OF THE ACCUMULATING SNOW. && .PREV DISCUSSION... /ISSUED 824 AM MST SAT DEC 21 2013/ AVIATION...DENSE FOG AT KDEN WITH RVRS MAINLY BELOW 1000 FT. THE FOG HAS LIFTED AT KBJC WITH ONLY LIGHT FOG AT KAPA...AND EROSION SHOULD CONTINUE FROM THE WEST/WEST-SOUTHWEST AS SURFACE WINDS ARE TRENDING THAT WAY. EXACT TIMING OF DISSIPATION AT KDEN IS DIFFICULT DUE TO HIGH CLOUDS MOVING OVER THE TOP...BUT AT THIS TIME EXPECT SOME IMPROVEMENT STARTING 16Z AND TOTAL EROSION EXPECTED BY 17Z-18Z. WILL CONTINUE TO MONITOR. PREV DISCUSSION... /ISSUED 528 AM MST SAT DEC 21 2013/ UPDATE... SHORT TERM...AREAS OF DENSE FOG HAVE EXPANDED THE PAST HOUR SO HAVE ISSUED AN ADVISORY BOUNDED BY A FORT COLLINS TO GREELEY TO FORT MORGAN TO DENVER LINE. AVIATION...WEAK DENVER CYCLONE WITH LIGHT NW WINDS HAS ALLOWED DENSE FOG OVER WELD COUNTY TO EXPAND SOUTHWARD INTO THE DENVER AREA. EXPECT THESE CONDITIONS WILL CONTINUE THROUGH 16Z. PREV DISCUSSION... /ISSUED 330 AM MST SAT DEC 21 2013/ SHORT TERM...SOME LOCALIZED FOG EARLY THIS MORNING EXTENDED FM FORT COLLINS TOWARDS FORT MORGAN AS SHOWN BY CIRA IMAGERY BUT SHOULD BURN OFF BY MID MORNING. OVERALL WILL CONTINUE TO SEE NW FLOW ALOFT THRU TONIGHT AS A FEW WEAK DISTURBANCES TRACK ACROSS NRN CO MAINLY TONIGHT. CROSS-SECTIONS SHOW MOISTURE WILL INCREASE IN THE MTNS BY THIS AFTN AND CONTINUE OVERNIGHT WITH FAVORABLE OROGRAPHICS AND LAPSE RATES AROUND 7 C/KM. THUS SNOW SHOULD INCREASE THIS AFTN AND CONTINUE OVERNIGHT SO WILL ISSUE A WINTER WEATHER WINTER ADVISORY WHICH WILL LINGER THRU MIDDAY SUN. OTHERWISE OVER NERN CO IT SHOULD BE DRY THRU THE AFTN ALTHOUGH COULD SEE A FEW LIGHT SNOW SHOWERS DEVELOP NR THE WY BORDER AND OVER THE PALMER DIVIDE LATE. HIGHS THIS AFTN WILL BE IN THE 30S OVER THE PLAINS. BY THIS EVENING A SURGE OF COOLER AIR WILL MOVE INTO NERN CO AND ENHANCE UPSLOPE FLOW ALONG THE FRONT RANGE. CROSS-SECTIONS SHOW INCREASING MOISTURE BEHIND THIS FNT AND AS WK DISTURBANCE MOVES ACROSS THIS EVENING SHOULD SEE A PERIOD OF LIGHT SNOW MAINLY IN AND NEAR THE FOOTHILLS. AT THIS TIME ACCUMULATIONS SHOULD BE ONLY AN INCH OR TWO. BY LATE TONIGHT THE UPSLOPE FLOW WILL GRADUALLY WEAKEN AFTER MIDNIGHT SO SNOW SHOULD GRADUALLY END BY 09Z OR SO. LONG TERM...BLOCKING MULTI-LEVEL HIGH PRESSURE RIDGE PRESENTLY OFF THE WEST COAST OF NORTH AMERICA SHOWS LITTLE SIGNS OF MOVEMENT DURING THE UPCOMING WEEK ACCORDING TO SHORT AND MEDIUM RANGE MODELS. AS A CONSEQUENCE COLORADO WILL REMAIN UNDER MODERATELY STRONG NORTHWEST FLOW DURING THE TIME PERIOD. MODELS SHOW A SERIES OF SUBTLE UNDULATIONS IN THIS FLOW ROUNDING THE TOP OF THE RIDGE AND PASSING OVER COLORADO...THE FIRST EXITING THE AREA SUNDAY MORNING...ANOTHER PASSING BY SUNDAY EVENING...AND YET ANOTHER PASSING THROUGH TUESDAY AFTERNOON AND/OR EVENING. RELYING ON THE MODELS TO RESOLVE THESE WEAK PERTABATIONS AND THEIR SPEED OF MOTION IN THIS FAST FLOW IS ASKING FOR DISAPPOINTMENT. THE SUNDAY EVENING SYSTEM APPEARS TO HAVE THE BEST POTENTIAL FOR PRODUCING SNOWFALL IN THE HIGH COUNTRY AND FOR PARTS OF NORTHEAST COLORADO. GFS IS THE MOST OPTIMISTIC OF THE MODELS WITH SNOW CHANCES ON THE PLAINS. HOWEVER THE NAM...GFS...ECMWF AND CANADIAN MODELS ALL INDICATE THE PRESENCE OF THIS WAVE OVER NORTHEAST COLORADO SUNDAY EVENING AND AT LEAST MIMINAL AMOUNTS OF QPF ACROSS THE NORTHEAST CORNER OF THE STATE. SURROUNDING WFOS CONCUR AND SO HAVE UPPED POPS TO 30-40 PCT IN ZONES ACROSS THE NORTHEAST CORNER SUNDAY EVENING. SHOULD THEN SEE PRECIP/SNOW CHANCES FALL OFF AFTER 07Z WITH THE JET LEVEL FORCING ALOFT EXITING THE AREA. ANY SNOW ACCUMULATION SHOULD BE MINIMAL. MEANWHILE MOUNTAINS AND HIGH VALLEYS HAVE A REASONABLE CHANCE OF MEASURING SNOWFALL WITH THIS SYSTEM. FOR NOW...WILL GO WITH 40-60 PCT POPS IN THE MTN ZONES AND 30-40 PCT POPS IN NORTH AND MIDDLE PARKS...ZONE 30 AND 32. SEE LITTLE IF ANY CHANCE OF SNOW FOR SOUTH PARK ZONE 37 AS NORTHWEST FLOW NOT CONDUCIVE FOR SNOWFALL HERE. COULD SEE A COUPLE INCHES OF SNOW ON THE NORTHERN MTN RIDGES AND HIGH PASSES BY MONDAY MORNING. NOT EXPECTING ANY SNOW IN THE I-25 URBAN CORRIDOR... EXCEPT PERHAPS A DUSTING UP NEAR THE WYOMING BORDER. THE LAST OF THESE WAVES IS PREDICTED BY THE EUROPEAN MODEL TO PASS OVER NORTHEAST COLORADO TUESDAY EVENING. WHEREAS THE GFS MODEL BARELY SHOWS A WAVE AND HARDLY ANY MOISTURE. HOWEVER...BOTH MODELS SHOW A WEAK COLD FRONT SLIPPING SOUTH ACROSS NORTHEAST COLORADO DURING THE AFTERNOON USHERING IN COLDER TEMPERATURES FOR TUESDAY NIGHT AND WEDNESDAY/CHRISTMAS DAY. SO FOR NOW...WILL HANG ONTO LOW POPS FOR TUESDAY EVENING IN THE MTNS...FOOTHILLS AND ALONG THE PALMER DIVIDE JUST IN CASE THE ECMWF IS CORRECT. WEDNESDAY AND BEYOND...A DRY AND COOL NORTHWEST FLOW REMAINS IN PLACE THROUGH THE END OF THE WEEK WITH A UPPER RIDGE STILL OFF THE WEST COAST. MODELS HINT AT THE PASSAGE OF YET ANOTHER SHORT WAVE DISTURBANCE EITHER THURSDAY AFTERNOON OR NIGHT. BUT CONFIDENCE IS LOW IN THE MODELS THAT FAR OUT. SO WILL KEEP THINGS DRY AND TEMPERATURES NEAR TO SLIGHTLY ABOVE AVERAGE THURSDAY AND FRIDAY. AVIATION...WINDS WERE SE EARLY THIS MORNING WITH CIRA IMAGERY SHOWING FOG CONFINED TO AREAS AROUND FORT COLLINS TO GREELEY. THE HRRR KEEPS THIS FOG AND LOW CLOUDS OVER WELD COUNTY THROUGH THE MORNING HOURS. HOWEVER THE RAP SHOWS A WEAK DENVER CYCLONE DEVELOPING WITH WINDS BECOMING LIGHT NNW BY SUNRISE WITH THE POTENTIAL FOR FOG AND LOW CLOUDS WHICH WOULD LINGER THRU THE LATE MORNING HOURS OVER DIA. AT THIS POINT WILL HAVE TO MONITOR TRENDS THE NEXT FEW HOURS AND SEE HOW THINGS DEVELOP. FOR TONIGHT A SURGE OF COOLER AIR WILL AFFECT THE AREA BEHIND A FNT WITH UPSLOPE FLOW DEVELOPING. AT THIS TIME MAY SEE A PERIOD OF LIGHT SNOW ESPECIALLY IN THE 02Z-08Z TIMEFRAME WITH UP TO AN INCH OF ACCUMULATION POSSIBLE. THE SNOW THREAT SHOULD END BY 09Z OR SO WITH IMPROVING CONDITIONS. && .BOU WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL NOON MST SUNDAY FOR COZ031-033-034. && $$ SHORT TERM...BARJENBRUCH LONG TERM....BAKER AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1042 AM MST SAT DEC 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 319 AM MST SAT DEC 21 2013 ...SOME SNOW FOR THE MOUNTAINS THROUGH THIS EVENING... MAIN FORECAST CHALLENGE TODAY IS STILL THE EXTENT OF LOW CLOUDS AND FOG OVER THE PLAINS AND VALLEYS. A STUBBORN PATCH OF STRATUS AND FOG HAS HUNG ON OVER NRN PUEBLO...SRN EL PASO...AND CROWLEY COUNTIES AND AS OF 230 AM STILL SHOWS NO SIGNS OF DISSIPATING AS WINDS REMAIN VERY LIGHT. GUIDANCE IS AGAIN NOT VERY HELPFUL...WITH NONE OF THE HIGH RES MODELS SHOWING ANY FOG DESPITE THE CURRENT CONDITIONS. THE RAP SOUNDING HAD FOG AT KCOS...BUT DISSIPATING QUICKLY AFTER 09Z...WHICH OBVIOUSLY IS NOT HAPPENING. THE SAN LUIS VALLEY ALSO PROBLEMATIC...AS SOME GUIDANCE...LIKE THE NAM...SHOWING SATURATED LOW LEVELS PERSISTING THROUGH THE DAY...WHILE THE RAP IS MUCH MORE OPTIMISTIC. HIGH RES WRF LOOKS LIKE A REASONABLE COMPROMISE FOR THE VALLEY...KEEPING THE LOW CLOUDS AROUND THROUGH MID MORNING...THEN INCREASING CLOUDS LATER TODAY AS THE NRN BRANCH SHORTWAVE SWINGS THROUGH OUR AREA. WILL STAY ON THE PESSIMISTIC SIDE OF THE FORECAST AND KEEP THE AREA CLOUDY WITH TEMPS ON THE LOW SIDE OF GUIDANCE...OR 20S FOR THE MTS AND HIGH VALLEYS AND 30S FOR THE PLAINS. BEST CHANCE OF SNOW FOR MOST OF THE AREA STILL LOOKS TO BE LATE THIS AFTERNOON THROUGH THIS EVE AS THE WAVE MOVES ACROSS. EXPECT THE BEST ACCUMS TO COME OVER THE HYR ELEVATIONS OF THE SANGRES..WETS...AND RAMPARTS. COULD SEE LOW END ADVISORY AMTS ABOVE 10000 FEET...IN THE 3 TO 6 INCH RANGE...BUT IMPACT SHOULD BE MINIMAL SO WILL HOLD OFF FROM ANY HEADLINES FOR NOW. MAY HAVE TO REEVALUATE IF 12Z RUNS SHOW AN UPWARD TREND. ONGOING LOW POPS FOR THE I-25 CORRIDOR THIS EVENING LOOK ON TARGET...BUT NOT EXPECTING MUCH IF ANY ACCUMULATION. PRECIP SHOULD WIND DOWN AFTER MIDNIGHT TONIGHT...AND IT WILL BE ANOTHER COLD NIGHT WITH TEMPS IN THE SINGLE DIGITS AND TEENS FOR THE MTS AND PLAINS RESPECTIVELY. ROSE .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 319 AM MST SAT DEC 21 2013 BY THE BEGINNING OF THIS PERIOD (12Z SUNDAY)...SHORTWAVE TROUGH IN THE NW FLOW ALOFT WILL BE EXITING THE REGION. A FEW SNOW SHOWERS WILL BE POSSIBLE EARLY IN THE DAY ACROSS THE PIKES PEAK REGION AND S MTNS...BUT SHOULD END BY NOON. SNOW SHOWERS WILL CONTINUE ACROSS THE C MTNS (NW SLOPES) THROUGHOUT THE DAY. SUNDAY NIGHT ANOTHER WEAK WAVE WILL MOVE SOUTHEAST IN THE NW FLOW ALOFT. THIS WILL KEEP SNOW SHOWERS ONGOING OVER THE C MTNS. SOME SNOW SHOWERS WILL ALSO BE POSSIBLE IN NE COLO AND WILL TRACK SOUTHEAST...BUT THESE SNOW SHOWERS SHOULD STAY OUT OF THE NWS PUB CWA. MONDAY INTO EARLY TUESDAY...WEAK RIDGING ALOFT WILL OCCUR...AND THIS SHOULD BRING PARTLY CLOUDY SKIES TO THE REGION. HOWEVER WE MAY SEE SOME WAVE CLOUDS ALONG THE GREATER I-25 CORRIDOR REGION DURING THIS PD. TEMPS SHOULD BE AOA SEASONABLE VALUES MON AND TUE. LATER ON TUESDAY ANOTHER COOL FRONT WILL MOVE ACROSS THE REGION LATE IN THE DAY. THE 00Z GFS WAS DRY WITH THIS SYSTEM WHILE THE EC CONTINUES TO BE A BIT STRONGER...AND BREAKS OUT SOME LIGHT PRECIP OVER THE GREATER S MTN REGION XMAS EVE INTO EARLY XMAS DAY. FOR THIS REASON I KEPT SOME SLIGHT POPS FOR THE PIKES PEAK REGION AND S MTNS/RATON MESA REGION. FOR THE REST OF THE PD...NW FLOW ALOFT CONTINUES WITH ANOTHER WEAK SHORT WAVE MOVING ACROSS THE REGION THU AFTERNOON. THIS WAVE WILL LIKELY BE DRY WITH A WEAK SURGE MOVING ACROSS THE PLAINS DURING THE DAY THU. /HODANISH && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1010 AM MST SAT DEC 21 2013 A WEATHER SYSTEM WILL MOVE THROUGH THE REGION THIS EVENING SPREADING A QUICK ROUND OF SNOW IN AND NEAR THE MOUNTAINS BETWEEN 20Z AND 12Z. KALS AND KCOS WILL SEE THE BEST CHANCE OF EXPERIENCING SOME -SHSN...THOUGH ANY ACCUMULATIONS AT THE TERMINALS WILL LIKELY STAY BELOW AN INCH. CIGS/VIS MAY BRIEFLY DROP INTO THE MVFR CATEGORY WITH -SHSN...WITH LOWER CIGS/VIS OVER/NEAR THE MOUNTAINS. CLEARING CONDITIONS WILL TAKE PLACE FROM NW TO SE AFTER 06Z. GUIDANCE AND BUFKIT MODEL SOUNDINGS SUGGEST KALS WILL GO DOWN IN FOG AGAIN SUNDAY MORNING BEHIND THE SYSTEM ONCE CLEARING TAKES PLACE. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...ROSE LONG TERM...HODANISH AVIATION...KT
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
824 AM MST SAT DEC 21 2013 .AVIATION...DENSE FOG AT KDEN WITH RVRS MAINLY BELOW 1000 FT. THE FOG HAS LIFTED AT KBJC WITH ONLY LIGHT FOG AT KAPA...AND EROSION SHOULD CONTINUE FROM THE WEST/WEST-SOUTHWEST AS SURFACE WINDS ARE TRENDING THAT WAY. EXACT TIMING OF DISSIPATION AT KDEN IS DIFFICULT DUE TO HIGH CLOUDS MOVING OVER THE TOP...BUT AT THIS TIME EXPECT SOME IMPROVEMENT STARTING 16Z AND TOTAL EROSION EXPECTED BY 17Z-18Z. WILL CONTINUE TO MONITOR. && .PREV DISCUSSION... /ISSUED 528 AM MST SAT DEC 21 2013/ UPDATE... SHORT TERM...AREAS OF DENSE FOG HAVE EXPANDED THE PAST HOUR SO HAVE ISSUED AN ADVISORY BOUNDED BY A FORT COLLINS TO GREELEY TO FORT MORGAN TO DENVER LINE. AVIATION...WEAK DENVER CYCLONE WITH LIGHT NW WINDS HAS ALLOWED DENSE FOG OVER WELD COUNTY TO EXPAND SOUTHWARD INTO THE DENVER AREA. EXPECT THESE CONDITIONS WILL CONTINUE THROUGH 16Z. PREV DISCUSSION... /ISSUED 330 AM MST SAT DEC 21 2013/ SHORT TERM...SOME LOCALIZED FOG EARLY THIS MORNING EXTENDED FM FORT COLLINS TOWARDS FORT MORGAN AS SHOWN BY CIRA IMAGERY BUT SHOULD BURN OFF BY MID MORNING. OVERALL WILL CONTINUE TO SEE NW FLOW ALOFT THRU TONIGHT AS A FEW WEAK DISTURBANCES TRACK ACROSS NRN CO MAINLY TONIGHT. CROSS-SECTIONS SHOW MOISTURE WILL INCREASE IN THE MTNS BY THIS AFTN AND CONTINUE OVERNIGHT WITH FAVORABLE OROGRAPHICS AND LAPSE RATES AROUND 7 C/KM. THUS SNOW SHOULD INCREASE THIS AFTN AND CONTINUE OVERNIGHT SO WILL ISSUE A WINTER WEATHER WINTER ADVISORY WHICH WILL LINGER THRU MIDDAY SUN. OTHERWISE OVER NERN CO IT SHOULD BE DRY THRU THE AFTN ALTHOUGH COULD SEE A FEW LIGHT SNOW SHOWERS DEVELOP NR THE WY BORDER AND OVER THE PALMER DIVIDE LATE. HIGHS THIS AFTN WILL BE IN THE 30S OVER THE PLAINS. BY THIS EVENING A SURGE OF COOLER AIR WILL MOVE INTO NERN CO AND ENHANCE UPSLOPE FLOW ALONG THE FRONT RANGE. CROSS-SECTIONS SHOW INCREASING MOISTURE BEHIND THIS FNT AND AS WK DISTURBANCE MOVES ACROSS THIS EVENING SHOULD SEE A PERIOD OF LIGHT SNOW MAINLY IN AND NEAR THE FOOTHILLS. AT THIS TIME ACCUMULATIONS SHOULD BE ONLY AN INCH OR TWO. BY LATE TONIGHT THE UPSLOPE FLOW WILL GRADUALLY WEAKEN AFTER MIDNIGHT SO SNOW SHOULD GRADUALLY END BY 09Z OR SO. LONG TERM...BLOCKING MULTI-LEVEL HIGH PRESSURE RIDGE PRESENTLY OFF THE WEST COAST OF NORTH AMERICA SHOWS LITTLE SIGNS OF MOVEMENT DURING THE UPCOMING WEEK ACCORDING TO SHORT AND MEDIUM RANGE MODELS. AS A CONSEQUENCE COLORADO WILL REMAIN UNDER MODERATELY STRONG NORTHWEST FLOW DURING THE TIME PERIOD. MODELS SHOW A SERIES OF SUBTLE UNDULATIONS IN THIS FLOW ROUNDING THE TOP OF THE RIDGE AND PASSING OVER COLORADO...THE FIRST EXITING THE AREA SUNDAY MORNING...ANOTHER PASSING BY SUNDAY EVENING...AND YET ANOTHER PASSING THROUGH TUESDAY AFTERNOON AND/OR EVENING. RELYING ON THE MODELS TO RESOLVE THESE WEAK PERTABATIONS AND THEIR SPEED OF MOTION IN THIS FAST FLOW IS ASKING FOR DISAPPOINTMENT. THE SUNDAY EVENING SYSTEM APPEARS TO HAVE THE BEST POTENTIAL FOR PRODUCING SNOWFALL IN THE HIGH COUNTRY AND FOR PARTS OF NORTHEAST COLORADO. GFS IS THE MOST OPTIMISTIC OF THE MODELS WITH SNOW CHANCES ON THE PLAINS. HOWEVER THE NAM...GFS...ECMWF AND CANADIAN MODELS ALL INDICATE THE PRESENCE OF THIS WAVE OVER NORTHEAST COLORADO SUNDAY EVENING AND AT LEAST MIMINAL AMOUNTS OF QPF ACROSS THE NORTHEAST CORNER OF THE STATE. SURROUNDING WFOS CONCUR AND SO HAVE UPPED POPS TO 30-40 PCT IN ZONES ACROSS THE NORTHEAST CORNER SUNDAY EVENING. SHOULD THEN SEE PRECIP/SNOW CHANCES FALL OFF AFTER 07Z WITH THE JET LEVEL FORCING ALOFT EXITING THE AREA. ANY SNOW ACCUMULATION SHOULD BE MINIMAL. MEANWHILE MOUNTAINS AND HIGH VALLEYS HAVE A REASONABLE CHANCE OF MEASURING SNOWFALL WITH THIS SYSTEM. FOR NOW...WILL GO WITH 40-60 PCT POPS IN THE MTN ZONES AND 30-40 PCT POPS IN NORTH AND MIDDLE PARKS...ZONE 30 AND 32. SEE LITTLE IF ANY CHANCE OF SNOW FOR SOUTH PARK ZONE 37 AS NORTHWEST FLOW NOT CONDUCIVE FOR SNOWFALL HERE. COULD SEE A COUPLE INCHES OF SNOW ON THE NORTHERN MTN RIDGES AND HIGH PASSES BY MONDAY MORNING. NOT EXPECTING ANY SNOW IN THE I-25 URBAN CORRIDOR... EXCEPT PERHAPS A DUSTING UP NEAR THE WYOMING BORDER. THE LAST OF THESE WAVES IS PREDICTED BY THE EUROPEAN MODEL TO PASS OVER NORTHEAST COLORADO TUESDAY EVENING. WHEREAS THE GFS MODEL BARELY SHOWS A WAVE AND HARDLY ANY MOISTURE. HOWEVER...BOTH MODELS SHOW A WEAK COLD FRONT SLIPPING SOUTH ACROSS NORTHEAST COLORADO DURING THE AFTERNOON USHERING IN COLDER TEMPERATURES FOR TUESDAY NIGHT AND WEDNESDAY/CHRISTMAS DAY. SO FOR NOW...WILL HANG ONTO LOW POPS FOR TUESDAY EVENING IN THE MTNS...FOOTHILLS AND ALONG THE PALMER DIVIDE JUST IN CASE THE ECMWF IS CORRECT. WEDNESDAY AND BEYOND...A DRY AND COOL NORTHWEST FLOW REMAINS IN PLACE THROUGH THE END OF THE WEEK WITH A UPPER RIDGE STILL OFF THE WEST COAST. MODELS HINT AT THE PASSAGE OF YET ANOTHER SHORT WAVE DISTURBANCE EITHER THURSDAY AFTERNOON OR NIGHT. BUT CONFIDENCE IS LOW IN THE MODELS THAT FAR OUT. SO WILL KEEP THINGS DRY AND TEMPERATURES NEAR TO SLIGHTLY ABOVE AVERAGE THURSDAY AND FRIDAY. AVIATION...WINDS WERE SE EARLY THIS MORNING WITH CIRA IMAGERY SHOWING FOG CONFINED TO AREAS AROUND FORT COLLINS TO GREELEY. THE HRRR KEEPS THIS FOG AND LOW CLOUDS OVER WELD COUNTY THROUGH THE MORNING HOURS. HOWEVER THE RAP SHOWS A WEAK DENVER CYCLONE DEVELOPING WITH WINDS BECOMING LIGHT NNW BY SUNRISE WITH THE POTENTIAL FOR FOG AND LOW CLOUDS WHICH WOULD LINGER THRU THE LATE MORNING HOURS OVER DIA. AT THIS POINT WILL HAVE TO MONITOR TRENDS THE NEXT FEW HOURS AND SEE HOW THINGS DEVELOP. FOR TONIGHT A SURGE OF COOLER AIR WILL AFFECT THE AREA BEHIND A FNT WITH UPSLOPE FLOW DEVELOPING. AT THIS TIME MAY SEE A PERIOD OF LIGHT SNOW ESPECIALLY IN THE 02Z-08Z TIMEFRAME WITH UP TO AN INCH OF ACCUMULATION POSSIBLE. THE SNOW THREAT SHOULD END BY 09Z OR SO WITH IMPROVING CONDITIONS. && .BOU WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM MST THIS MORNING FOR COZ038>040- 043>045. WINTER WEATHER ADVISORY FROM NOON TODAY TO NOON MST SUNDAY FOR COZ031-033-034. && $$ SHORT TERM...RPK LONG TERM....BAKER AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
528 AM MST SAT DEC 21 2013 .UPDATE... && .SHORT TERM...AREAS OF DENSE FOG HAVE EXPANDED THE PAST HOUR SO HAVE ISSUED AN ADVISORY BOUNDED BY A FORT COLLINS TO GREELEY TO FORT MORGAN TO DENVER LINE. .AVIATION...WEAK DENVER CYCLONE WITH LIGHT NW WINDS HAS ALLOWED DENSE FOG OVER WELD COUNTY TO EXPAND SOUTHWARD INTO THE DENVER AREA. EXPECT THESE CONDITIONS WILL CONTINUE THROUGH 16Z. && .PREV DISCUSSION... /ISSUED 330 AM MST SAT DEC 21 2013/ SHORT TERM...SOME LOCALIZED FOG EARLY THIS MORNING EXTENDED FM FORT COLLINS TOWARDS FORT MORGAN AS SHOWN BY CIRA IMAGERY BUT SHOULD BURN OFF BY MID MORNING. OVERALL WILL CONTINUE TO SEE NW FLOW ALOFT THRU TONIGHT AS A FEW WEAK DISTURBANCES TRACK ACROSS NRN CO MAINLY TONIGHT. CROSS-SECTIONS SHOW MOISTURE WILL INCREASE IN THE MTNS BY THIS AFTN AND CONTINUE OVERNIGHT WITH FAVORABLE OROGRAPHICS AND LAPSE RATES AROUND 7 C/KM. THUS SNOW SHOULD INCREASE THIS AFTN AND CONTINUE OVERNIGHT SO WILL ISSUE A WINTER WEATHER WINTER ADVISORY WHICH WILL LINGER THRU MIDDAY SUN. OTHERWISE OVER NERN CO IT SHOULD BE DRY THRU THE AFTN ALTHOUGH COULD SEE A FEW LIGHT SNOW SHOWERS DEVELOP NR THE WY BORDER AND OVER THE PALMER DIVIDE LATE. HIGHS THIS AFTN WILL BE IN THE 30S OVER THE PLAINS. BY THIS EVENING A SURGE OF COOLER AIR WILL MOVE INTO NERN CO AND ENHANCE UPSLOPE FLOW ALONG THE FRONT RANGE. CROSS-SECTIONS SHOW INCREASING MOISTURE BEHIND THIS FNT AND AS WK DISTURBANCE MOVES ACROSS THIS EVENING SHOULD SEE A PERIOD OF LIGHT SNOW MAINLY IN AND NEAR THE FOOTHILLS. AT THIS TIME ACCUMULATIONS SHOULD BE ONLY AN INCH OR TWO. BY LATE TONIGHT THE UPSLOPE FLOW WILL GRADUALLY WEAKEN AFTER MIDNIGHT SO SNOW SHOULD GRADUALLY END BY 09Z OR SO. LONG TERM...BLOCKING MULTI-LEVEL HIGH PRESSURE RIDGE PRESENTLY OFF THE WEST COAST OF NORTH AMERICA SHOWS LITTLE SIGNS OF MOVEMENT DURING THE UPCOMING WEEK ACCORDING TO SHORT AND MEDIUM RANGE MODELS. AS A CONSEQUENCE COLORADO WILL REMAIN UNDER MODERATELY STRONG NORTHWEST FLOW DURING THE TIME PERIOD. MODELS SHOW A SERIES OF SUBTLE UNDULATIONS IN THIS FLOW ROUNDING THE TOP OF THE RIDGE AND PASSING OVER COLORADO...THE FIRST EXITING THE AREA SUNDAY MORNING...ANOTHER PASSING BY SUNDAY EVENING...AND YET ANOTHER PASSING THROUGH TUESDAY AFTERNOON AND/OR EVENING. RELYING ON THE MODELS TO RESOLVE THESE WEAK PERTABATIONS AND THEIR SPEED OF MOTION IN THIS FAST FLOW IS ASKING FOR DISAPPOINTMENT. THE SUNDAY EVENING SYSTEM APPEARS TO HAVE THE BEST POTENTIAL FOR PRODUCING SNOWFALL IN THE HIGH COUNTRY AND FOR PARTS OF NORTHEAST COLORADO. GFS IS THE MOST OPTIMISTIC OF THE MODELS WITH SNOW CHANCES ON THE PLAINS. HOWEVER THE NAM...GFS...ECMWF AND CANADIAN MODELS ALL INDICATE THE PRESENCE OF THIS WAVE OVER NORTHEAST COLORADO SUNDAY EVENING AND AT LEAST MIMINAL AMOUNTS OF QPF ACROSS THE NORTHEAST CORNER OF THE STATE. SURROUNDING WFOS CONCUR AND SO HAVE UPPED POPS TO 30-40 PCT IN ZONES ACROSS THE NORTHEAST CORNER SUNDAY EVENING. SHOULD THEN SEE PRECIP/SNOW CHANCES FALL OFF AFTER 07Z WITH THE JET LEVEL FORCING ALOFT EXITING THE AREA. ANY SNOW ACCUMULATION SHOULD BE MINIMAL. MEANWHILE MOUNTAINS AND HIGH VALLEYS HAVE A REASONABLE CHANCE OF MEASURING SNOWFALL WITH THIS SYSTEM. FOR NOW...WILL GO WITH 40-60 PCT POPS IN THE MTN ZONES AND 30-40 PCT POPS IN NORTH AND MIDDLE PARKS...ZONE 30 AND 32. SEE LITTLE IF ANY CHANCE OF SNOW FOR SOUTH PARK ZONE 37 AS NORTHWEST FLOW NOT CONDUCIVE FOR SNOWFALL HERE. COULD SEE A COUPLE INCHES OF SNOW ON THE NORTHERN MTN RIDGES AND HIGH PASSES BY MONDAY MORNING. NOT EXPECTING ANY SNOW IN THE I-25 URBAN CORRIDOR... EXCEPT PERHAPS A DUSTING UP NEAR THE WYOMING BORDER. THE LAST OF THESE WAVES IS PREDICTED BY THE EUROPEAN MODEL TO PASS OVER NORTHEAST COLORADO TUESDAY EVENING. WHEREAS THE GFS MODEL BARELY SHOWS A WAVE AND HARDLY ANY MOISTURE. HOWEVER...BOTH MODELS SHOW A WEAK COLD FRONT SLIPPING SOUTH ACROSS NORTHEAST COLORADO DURING THE AFTERNOON USHERING IN COLDER TEMPERATURES FOR TUESDAY NIGHT AND WEDNESDAY/CHRISTMAS DAY. SO FOR NOW...WILL HANG ONTO LOW POPS FOR TUESDAY EVENING IN THE MTNS...FOOTHILLS AND ALONG THE PALMER DIVIDE JUST IN CASE THE ECMWF IS CORRECT. WEDNESDAY AND BEYOND...A DRY AND COOL NORTHWEST FLOW REMAINS IN PLACE THROUGH THE END OF THE WEEK WITH A UPPER RIDGE STILL OFF THE WEST COAST. MODELS HINT AT THE PASSAGE OF YET ANOTHER SHORT WAVE DISTURBANCE EITHER THURSDAY AFTERNOON OR NIGHT. BUT CONFIDENCE IS LOW IN THE MODELS THAT FAR OUT. SO WILL KEEP THINGS DRY AND TEMPERATURES NEAR TO SLIGHTLY ABOVE AVERAGE THURSDAY AND FRIDAY. AVIATION...WINDS WERE SE EARLY THIS MORNING WITH CIRA IMAGERY SHOWING FOG CONFINED TO AREAS AROUND FORT COLLINS TO GREELEY. THE HRRR KEEPS THIS FOG AND LOW CLOUDS OVER WELD COUNTY THROUGH THE MORNING HOURS. HOWEVER THE RAP SHOWS A WEAK DENVER CYCLONE DEVELOPING WITH WINDS BECOMING LIGHT NNW BY SUNRISE WITH THE POTENTIAL FOR FOG AND LOW CLOUDS WHICH WOULD LINGER THRU THE LATE MORNING HOURS OVER DIA. AT THIS POINT WILL HAVE TO MONITOR TRENDS THE NEXT FEW HOURS AND SEE HOW THINGS DEVELOP. FOR TONIGHT A SURGE OF COOLER AIR WILL AFFECT THE AREA BEHIND A FNT WITH UPSLOPE FLOW DEVELOPING. AT THIS TIME MAY SEE A PERIOD OF LIGHT SNOW ESPECIALLY IN THE 02Z-08Z TIMEFRAME WITH UP TO AN INCH OF ACCUMULATION POSSIBLE. THE SNOW THREAT SHOULD END BY 09Z OR SO WITH IMPROVING CONDITIONS. && .BOU WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM MST THIS MORNING FOR COZ038>040- 043>045. WINTER WEATHER ADVISORY FROM NOON TODAY TO NOON MST SUNDAY FOR COZ031-033-034. && $$ SHORT TERM...RPK LONG TERM....BAKER AVIATION...RPK
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
330 AM MST SAT DEC 21 2013 .SHORT TERM...SOME LOCALIZED FOG EARLY THIS MORNING EXTENDED FM FORT COLLINS TOWARDS FORT MORGAN AS SHOWN BY CIRA IMAGERY BUT SHOULD BURN OFF BY MID MORNING. OVERALL WILL CONTINUE TO SEE NW FLOW ALOFT THRU TONIGHT AS A FEW WEAK DISTURBANCES TRACK ACROSS NRN CO MAINLY TONIGHT. CROSS-SECTIONS SHOW MOISTURE WILL INCREASE IN THE MTNS BY THIS AFTN AND CONTINUE OVERNIGHT WITH FAVORABLE OROGRAPHICS AND LAPSE RATES AROUND 7 C/KM. THUS SNOW SHOULD INCREASE THIS AFTN AND CONTINUE OVERNIGHT SO WILL ISSUE A WINTER WEATHER WINTER ADVISORY WHICH WILL LINGER THRU MIDDAY SUN. OTHERWISE OVER NERN CO IT SHOULD BE DRY THRU THE AFTN ALTHOUGH COULD SEE A FEW LIGHT SNOW SHOWERS DEVELOP NR THE WY BORDER AND OVER THE PALMER DIVIDE LATE. HIGHS THIS AFTN WILL BE IN THE 30S OVER THE PLAINS. BY THIS EVENING A SURGE OF COOLER AIR WILL MOVE INTO NERN CO AND ENHANCE UPSLOPE FLOW ALONG THE FRONT RANGE. CROSS-SECTIONS SHOW INCREASING MOISTURE BEHIND THIS FNT AND AS WK DISTURBANCE MOVES ACROSS THIS EVENING SHOULD SEE A PERIOD OF LIGHT SNOW MAINLY IN AND NEAR THE FOOTHILLS. AT THIS TIME ACCUMULATIONS SHOULD BE ONLY AN INCH OR TWO. BY LATE TONIGHT THE UPSLOPE FLOW WILL GRADUALLY WEAKEN AFTER MIDNIGHT SO SNOW SHOULD GRADUALLY END BY 09Z OR SO. .LONG TERM...BLOCKING MULTI-LEVEL HIGH PRESSURE RIDGE PRESENTLY OFF THE WEST COAST OF NORTH AMERICA SHOWS LITTLE SIGNS OF MOVEMENT DURING THE UPCOMING WEEK ACCORDING TO SHORT AND MEDIUM RANGE MODELS. AS A CONSEQUENCE COLORADO WILL REMAIN UNDER MODERATELY STRONG NORTHWEST FLOW DURING THE TIME PERIOD. MODELS SHOW A SERIES OF SUBTLE UNDULATIONS IN THIS FLOW ROUNDING THE TOP OF THE RIDGE AND PASSING OVER COLORADO...THE FIRST EXITING THE AREA SUNDAY MORNING...ANOTHER PASSING BY SUNDAY EVENING...AND YET ANOTHER PASSING THROUGH TUESDAY AFTERNOON AND/OR EVENING. RELYING ON THE MODELS TO RESOLVE THESE WEAK PERTABATIONS AND THEIR SPEED OF MOTION IN THIS FAST FLOW IS ASKING FOR DISAPPOINTMENT. THE SUNDAY EVENING SYSTEM APPEARS TO HAVE THE BEST POTENTIAL FOR PRODUCING SNOWFALL IN THE HIGH COUNTRY AND FOR PARTS OF NORTHEAST COLORADO. GFS IS THE MOST OPTIMISTIC OF THE MODELS WITH SNOW CHANCES ON THE PLAINS. HOWEVER THE NAM...GFS...ECMWF AND CANADIAN MODELS ALL INDICATE THE PRESENCE OF THIS WAVE OVER NORTHEAST COLORADO SUNDAY EVENING AND AT LEAST MIMINAL AMOUNTS OF QPF ACROSS THE NORTHEAST CORNER OF THE STATE. SURROUNDING WFOS CONCUR AND SO HAVE UPPED POPS TO 30-40 PCT IN ZONES ACROSS THE NORTHEAST CORNER SUNDAY EVENING. SHOULD THEN SEE PRECIP/SNOW CHANCES FALL OFF AFTER 07Z WITH THE JET LEVEL FORCING ALOFT EXITING THE AREA. ANY SNOW ACCUMULATION SHOULD BE MINIMAL. MEANWHILE MOUNTAINS AND HIGH VALLEYS HAVE A REASONABLE CHANCE OF MEASURING SNOWFALL WITH THIS SYSTEM. FOR NOW...WILL GO WITH 40-60 PCT POPS IN THE MTN ZONES AND 30-40 PCT POPS IN NORTH AND MIDDLE PARKS...ZONE 30 AND 32. SEE LITTLE IF ANY CHANCE OF SNOW FOR SOUTH PARK ZONE 37 AS NORTHWEST FLOW NOT CONDUCIVE FOR SNOWFALL HERE. COULD SEE A COUPLE INCHES OF SNOW ON THE NORTHERN MTN RIDGES AND HIGH PASSES BY MONDAY MORNING. NOT EXPECTING ANY SNOW IN THE I-25 URBAN CORRIDOR... EXCEPT PERHAPS A DUSTING UP NEAR THE WYOMING BORDER. THE LAST OF THESE WAVES IS PREDICTED BY THE EUROPEAN MODEL TO PASS OVER NORTHEAST COLORADO TUESDAY EVENING. WHEREAS THE GFS MODEL BARELY SHOWS A WAVE AND HARDLY ANY MOISTURE. HOWEVER...BOTH MODELS SHOW A WEAK COLD FRONT SLIPPING SOUTH ACROSS NORTHEAST COLORADO DURING THE AFTERNOON USHERING IN COLDER TEMPERATURES FOR TUESDAY NIGHT AND WEDNESDAY/CHRISTMAS DAY. SO FOR NOW...WILL HANG ONTO LOW POPS FOR TUESDAY EVENING IN THE MTNS...FOOTHILLS AND ALONG THE PALMER DIVIDE JUST IN CASE THE ECMWF IS CORRECT. WEDNESDAY AND BEYOND...A DRY AND COOL NORTHWEST FLOW REMAINS IN PLACE THROUGH THE END OF THE WEEK WITH A UPPER RIDGE STILL OFF THE WEST COAST. MODELS HINT AT THE PASSAGE OF YET ANOTHER SHORT WAVE DISTURBANCE EITHER THURSDAY AFTERNOON OR NIGHT. BUT CONFIDENCE IS LOW IN THE MODELS THAT FAR OUT. SO WILL KEEP THINGS DRY AND TEMPERATURES NEAR TO SLIGHTLY ABOVE AVERAGE THURSDAY AND FRIDAY. && .AVIATION...WINDS WERE SE EARLY THIS MORNING WITH CIRA IMAGERY SHOWING FOG CONFINED TO AREAS AROUND FORT COLLINS TO GREELEY. THE HRRR KEEPS THIS FOG AND LOW CLOUDS OVER WELD COUNTY THROUGH THE MORNING HOURS. HOWEVER THE RAP SHOWS A WEAK DENVER CYCLONE DEVELOPING WITH WINDS BECOMING LIGHT NNW BY SUNRISE WITH THE POTENTIAL FOR FOG AND LOW CLOUDS WHICH WOULD LINGER THRU THE LATE MORNING HOURS OVER DIA. AT THIS POINT WILL HAVE TO MONITOR TRENDS THE NEXT FEW HOURS AND SEE HOW THINGS DEVELOP. FOR TONIGHT A SURGE OF COOLER AIR WILL AFFECT THE AREA BEHIND A FNT WITH UPSLOPE FLOW DEVELOPING. AT THIS TIME MAY SEE A PERIOD OF LIGHT SNOW ESPECIALLY IN THE 02Z-08Z TIMEFRAME WITH UP TO AN INCH OF ACCUMULATION POSSIBLE. THE SNOW THREAT SHOULD END BY 09Z OR SO WITH IMPROVING CONDITIONS. && .BOU WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM NOON TODAY TO NOON MST SUNDAY FOR COZ031-033-034. && $$ SHORT TERM...RPK LONG TERM....BAKER AVIATION...RPK
AREA FORECAST DISCUSSION
NWS ALBANY NY
626 AM EST SAT DEC 21 2013 .SYNOPSIS... A SERIES OF LOW PRESSURE WAVES WILL PROPAGATE ALONG A NEARLY STATIONARY FRONT FROM THE GREAT LAKES THROUGH NORTHERN NEW YORK AND NORTHERN NEW ENGLAND THROUGH TONIGHT. A MUCH STRONGER STORM WILL MOVE OUT OF THE OHIO VALLEY SUNDAY ALONG THIS FRONT. IN ITS WAKE COLDER AIR WILL FILER BACK INTO THE REGION FOR THE FIRST HALF OF THE WEEK. THE WEEKEND WILL FEATURE MILD TEMPERATURES FOR DECEMBER...PERIODS OF RAIN BECOMING WIDESPREAD LATE SATURDAY INTO SUNDAY WITH FREEZING RAIN ALONG THE NORTHERN TIER OF NEW YORK AND NEW ENGLAND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 626 AM EST...A STALLED SURFACE FRONTAL BOUNDARY IS SITUATED ACROSS FAR NORTHERN NEW YORK. AS A WEAK WAVE OF LOW PRESSURE MOVES ALONG THIS BOUNDARY...THE FRONT WILL DROP SOUTH ACROSS THE NORTHERN PORTION OF OUR CWA LATER TODAY. PERIODS OF RAIN WILL ACCOMPANY THIS FRONTAL BOUNDARY THROUGHOUT THE DAY TODAY. THE LATEST 3KM HRRR SUGGESTS ONE BATCH OF RAINFALL WILL MOVE ACROSS THE REGION THIS MORNING...WITH A MORE STEADIER AND HEAVIER BATCH OF RAIN TO OCCUR LATER THIS AFTERNOON AND INTO TONIGHT. TEMPS HAVE WARMED UP ABOVE FREEZING ACROSS THE ENTIRE CWA...SO THERE IS NO LONGER ANY THREAT FOR FZRA THIS MORNING. A STRONG SOUTHERLY FLOW AT LOW LEVELS HAS ALLOWED TEMPS TO RANGE FROM THE UPPER 30S TO UPPER 40S. DESPITE OVERCAST SKIES...TEMPS WILL CONTINUE TO BE ABOVE NORMAL TODAY...AS A SOUTHERLY FLOW CONTINUES TO THE SOUTH OF THE FRONTAL BOUNDARY. MAX TEMPS WILL GENERALLY BE IN THE 40S...WITH SOME TEMPS NEAR 50 IN THE MID HUDSON VALLEY. TONIGHT...THE FRONTAL BOUNDARY WILL BECOME STALLED ACROSS ADIRONDACKS...AS ANOTHER AND MUCH STRONGER WAVE OF LOW PRESSURE BEGINS TO APPROACH FROM THE MISSISSIPPI AND TENNESSEE VALLEY REGION. THERE WILL BE A STRONG THERMAL GRADIENT ASSOCIATED WITH THIS BOUNDARY...WHICH WILL ALLOW FOR STRONG ISENTROPIC LIFT. 850 HPA TEMPS WILL RANGE FROM AROUND +5 C OVER THE WESTERN ADIRONDACKS THIS EVENING TO AS HIGH AS +14 DEGREES C BY LATE TONIGHT OVER THE SOUTHEASTERN CORNER OF THE CWA. WITH A STRONG AREA OF HIGH PRESSURE OVER WESTERN QUEBEC...THERE WILL BE A VERY COLD AND DENSE AIR MASS SITUATED JUST NORTH OF OUR AREA. THE STRONG AGEOSTROPHIC FLOW AT 925 HPA WILL ALLOW THIS COLD DENSE AIR TO GET PULLED SOUTHWARD DOWN THE CHAMPLAIN VALLEY TONIGHT. AS A RESULT...SFC TEMPS ACROSS THE LAKE GEORGE AREA WILL DROP BELOW FREEZING ONCE AGAIN. WITH A WIDESPREAD RAIN EXPECTED OVERNIGHT...THIS RAIN WILL FREEZE ON CONTACT...RESULTING IN FREEZING RAIN ACROSS NORTHEASTERN WARREN AND NORTHERN WASHINGTON COUNTIES. WE HAVE ISSUED A FREEZING RAIN ADVISORY TO ACCOUNT FOR THIS...WITH A FEW TENTHS OF AN INCH POSSIBLE IN THESE LOCATIONS. THERE MAY BE A FEW POCKETS OF FREEZING RAIN ACROSS THE FAR NORTHWESTERN ADIRONDACKS...MAINLY NORTH OF OLD FORGE AND NORTHWEST OF INDIAN LAKE...BUT ANY ICE ACCRETION IN THESE AREAS WILL BE VERY LIMITED AND LOCALIZED. ELSEWHERE...A WIDESPREAD MODERATE TO LOCALLY HEAVY RAIN WILL OCCUR FROM ABOUT THE CAPITAL REGION ON NORTH OVERNIGHT. SOME RAIN WILL OCCUR ACROSS SOUTHERN AREAS AS WELL...ALTHOUGH THE BEST PRECIP WILL BE LOCATED CLOSER TO THE TIGHT BAROCLINIC ZONE ACROSS THE NORTHERN PORTION OF THE CWA. OUTSIDE OF THE LAKE GEORGE AREA...TEMPS LOOK TO HOLD STEADY AND/OR SLOWLY RISE OVERNIGHT...WITH MIN TEMPS OCCURRING EARLY IN THE PERIOD AND RANGING FROM THE MID 30S TO MID 40S. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... BY SUNDAY MORNING STATIONARY FRONT REMAINS DRAPED FROM SW NYS TO NR PWM. OVERRUNNING HAD BEEN THE PRIMARY DRIVER OF UVM AND PCPN THROUGH SAT NT ALONG WITH AGEO CIRC ASSOC WITH RIGHT ENTRANCE RGN OF INTENSE 300HPA JET. RAINS WILL HAVE OVERSPREAD THE ENTIRE FCA MUCH OF THE NIGHT. BY SUN MRNG GFS HAS OVER 2 IN QPF IN ADIRONDACKS TO LESS THAN 1 TENTH IN MID HUD VLY WITH A SOMEWHAT MORE GENEROUS MAX IN THE NAM OF 2.6 IN. SUNDAY A SHARP SHORT WV EJECTS INTO THE UPR MIDWEST...TRIGGERING A MUCH DEEPER CYCLOGENESIS IN THE OHIO VLY THAN THE WAVES THAT HAD BEEN RIPPLING ALONG THE STATIONARY FRONT TO THIS POINT. THE LOW DEEPENS AS IT MOVES ACROSS FCA SUN. IN ADDITION THE PREVIOUSLY ACTING ISENTROPIC LIFT AND JET DYNAMICS...CONVERGENCE WITH THE LOW AND ALONG THE WMFNT WILL ENHANCE A BURST OF PCPN SUN WORKING WITH RICH AIR MASS AND PW OF 1.25 IN OR BETTER. SUNDAY THE MDLS DUMP ANOTHER TENTH OF AN INCH QPF IN MID HUD VLY WITH ANOTHER TO 1.25 INCHES IN ADRNDKS. THE GEM HAS SIMILAR NUMBERS WITH A MAX SHIFTED SLIGHTLY TO THE N OF US MDLS AND A FRONTAL POSITION 50 OR SO MILES N. IN SUMMARY QPF VALUES FM DETERMINISTIC MDLS ARE ANOTHER 0.5 TO 1.0 INCHES GREATER THAN PVS QPF. TOTALS ARE ON THE ORDER FROM 0.25 MID HUD VLY TO 3 PLUS INCHES IN ADRNDKS. THE ECMWF AND GEM ARE ON THE LIGHTER SIDE WITH A MAX QPF CLOSER TO 2 INCHES TOTAL. ADD TO THAT THE SNOW PACK MELT. BY SUNDAY SNOW PACK WILL BE RIPE OR RIPENING N. MOST WILL BE GONE IN THE SE. IN THE SE 1.0 LIQ OF SNOW PACK AND A HALF AN INCH OF QPF SHOULDN`T PUSH RIVERS OUT OF THEIR BANKS. HWVR FURTHER N...COLDER TEMPS EARLIER IN THE PERIOD HAVE SLOWED SNOW MELT...WILL GIVE WAY TO 40S SUN WITH 2-3 INCHES OF QPF..AND MAYBE AN INCH OF SNOW MELT. AT THIS POINT WILL ISSUE A FLOOD WATCH FOR SAT NT THROUGH SUN...WITH 2-3 IN QPF N TIER...AN INCH OF SNOW MELT. POTENTIAL FOR WIDESPREAD MINOR FLOODING INCRG. BY SUN NT SFC LOW EXISTS NY INTO N NEW ENG AND DRY SLOT MOVES INTO RGN. RN SHOULD DIM TO SCT -SHRA BUT TEMPS WILL REMAIN ABV FREEZING ACROSS MOST AREA...AND SNOW MELT AND RUNOFF WILL CONTINUE. DURING SUNDAY AND SUN NT TEMPS ARE EITHER NON DIURNAL OR MAV/MET MAX MIN VALUES ARE 24 HR VALUES FM SAT. WILL USE 3 HRLY TEMPS IN GRIDS. MONDAY THE SFC LOW AND ITS CDFNT MOVE EAST OF RGN. FCA WILL BE IN DRY SLOT WITH VERY GRADUAL CAA. HWVR AT 500HPA MAJOR TROF IS BEING CARVED OUT OVER GRTLKS AS SERIES OF SHORT WVS DIG S INTO IT. THIS KEEPS A SW 500HPA FLOW OVR RGN...RESULTING IN A GRADUAL EXIT OF FRONTAL SYSTEM AND GRADUAL COOL DOWN MONDAY. GFS/ECM PUSH SOME PCPN INTO INTO FAR SE CORNER OF FCA MON. THIS IS MUCH LESS PRONOUNCED THAN PVS RUNS...AND REALLY ONLY JUSTIFIES MAINTAINING CHC POPS AT THIS TIME. DURING MON AND TUE CAA AND INCRG WIND GRADIENT WILL BE THE RULE AS TEMPS RETURN TO NR OR BLO NORMAL TUES WITH PASSAGE OF 500HPA TROF THROUGH RGN MONDAY NT AND TUES. ITS FOLLOWED BY A MUCH STRONGER CDFNT AND BRISK N-NE WINDS IN ITS WAKE. CDFNT PASSAGE WILL TRIGGER SCT -SHSN MON NT...BUT H850 AND LLVL FLOW NOT FAVORABLE FOR LK RESPONSE IN FCA TUE. TUES TEMPS WILL BE SVRL DEG BLO NORMAL AS SFC HIGH BEGINS BUILDING SE FM OTTAWA VLY. 500HPA TROF MAY STILL BE SUF TO TRIGGER SCT INSTAB -SHSN TUES AND TUE NT. SKIES WILL BE PC WITH MORE CLOUDS N AND FEWER S MON-TUE. CHRISTMAS DAY WILL START ON THE FRIGID SIDE AS CLR SKIES...LARGE SFC HIGH OVER RGN AND SOME OF THE LONGEST NIGHTS OF THE YEAR WILL ALLOW IDEAL RADIATIONAL COOLING. MEX LOWS AT SLK ARE -19F TO +10 AT POU. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... CHRISTMAS DAY 500HPA AND SFC RIDGE WILL CREST OVR RGN RESULTING IN FAIR RATHER COLD DAY. AFTER FRIGID START TEMPS WILL REBOUND TO THE TEENS AND LOW 20S. BY EVENING THE FLOW REGIME FOR THE REST OF THE WEEK WILL BE SETTING UP WITH FAST W-NW FLOW ACROSS RGN. CLIPPER TYPE TROF IN GFS (ECMWF CUTS IT OFF) RACES THROUGH UPR GRTLKS WED NT INTO QB THU LEAVING AREA IN SLIGHTLY MILDER AIR MASS. SOME MODELS SUG SOME -SHSN WITH IT...BUT MINOR AMOUNTS OR FLURRIES. WEEK ENDS WITH GFS PUSHING A CDFNT INTO RGN AND BECOMING AN ANNA TYPE FRONT WITH A PERIOD OF -SN SUGGESTED FRI FOLLOWED BY STRONG CAA AND SOME LK EFFECT SAT. THE ECMWF CUTS OFF THE 500HPA LOW THU AND BRINGS THIS FRONT QUICKLY THROUGH WITH THE CLIPPER THU. AS THIS IS MAINLY A BLO NORMAL TEMP PERIOD WITH RATHER NON DESCRIPT WX TIED TO FAST MOVING SYSTEMS WILL POPULATE REMAINDER OF EFP WITH HPC MID SHIFT GRIDS. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... FLYING CONDITIONS ARE CURRENTLY HIGH END MVFR TO VFR ACROSS THE REGION WITH INCREASING AMOUNTS OF CLOUDINESS. REGIONAL MOSAIC RADAR SHOWS RAIN SHOWERS APPROACHING FROM CENTRAL NY FOR LATER THIS MORNING. THIS WILL ALLOW FOR WIDESPREAD MVFR CONDITIONS...AND POSSIBLY PERIODS OF IFR FOR THE MID TO LATE MORNING HOURS INTO THE EARLY AFTN DUE TO RAIN...MIST AND LOW STRATUS CLOUDS. IT MAY TAKE UNTIL LATE IN THE DAY FOR THE RAIN TO REACH KPOU...WHEN A MORE STEADIER AND HEAVIER RAINFALL ARRIVES. THIS RAIN WILL CONTINUE THROUGH TONIGHT WITH WIDESPREAD IFR CONDITIONS. LLWS WILL BE IN PLACE THROUGH EARLY THIS AFTN WITH 2 KFT WINDS AROUND 35-40 KTS OUT OF THE WEST-SOUTHWEST. MEANWHILE...SFC WINDS WILL BE MAINLY LIGHT...BECOMING SOUTHERLY AT 10 KTS OR LESS. LLWS SHOULD END BY THIS AFTN AS THE BEST LOW LEVEL JET SHIFTS AWAY FROM THE AREA. SFC WINDS WILL REMAIN LIGHT RIGHT INTO TONIGHT. OUTLOOK... SUNDAY: HIGH OPERATIONAL IMPACT. RA. SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA. MONDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. MONDAY NIGHT-TUESDAY NIGHT: LOW OPERATIONAL IMPACT. BREEZY. SLIGHT CHANCE OF SHSN. CHRISTMAS DAY-WED NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. && .HYDROLOGY... MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THROUGH THE WEEKEND WITH INCREASING SNOW MELT. MEANWHILE A SERIES OF LOW PRESSURE SYSTEMS WILL BE PROPAGATING ALONG A NEARLY STATIONARY FRONT FROM THE NIAGARA FRONTIER TO VERMONT WITH 2-3 INCHES OF RAIN EXPECTED IN THE ADIRONDACKS...BUT LESSER AMOUNTS SOUTH. TEMPERATURES SUNDAY ARE EXPECTED TO WARM INTO THE 50S IN MOST AREAS...MID 40S FAR NORTH AND 60S SOUTH OF ALBANY. IN THE NORTH RAINFALL AMOUNTS WILL BE GREATEST...BUT SNOW MELT SLOWER...WHILE IN THE SOUTH RAINFALL WILL BE AROUND A HALF INCH...BUT ALMOST ALL SNOW WILL MELT. IN THE SOUTH THIS WILL BE SUFFICIENT FOR SIGNIFICANT WITHIN BANK RISES...BUT FLOODING IS NOT EXPECTED AT THIS TIME. THE GREATEST POTENTIAL FOR FLOODING WILL EXIST FROM THE MOHAWK VALLEY INTO THE ADIRONDACKS WHERE 2 TO 3 INCHES OF RAIN AND UP TO AN INCH OF LIQUID EQUIVALENT FROM SNOW MELT IS EXPECTED. FLOOD WATCHES HAVE BEEN ISSUED FOR TONIGHT THROUGH SUNDAY NIGHT. 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...FLOOD WATCH FROM THIS EVENING THROUGH MONDAY MORNING FOR NYZ032-033-038>040-042-043-082. FREEZING RAIN ADVISORY FROM 7 PM THIS EVENING TO 11 AM EST SUNDAY FOR NYZ042-043. 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
222 AM EST SAT DEC 21 2013 .SYNOPSIS... A SERIES OF LOW PRESSURE WAVES WILL PROPAGATE ALONG A NEARLY STATIONARY FRONT FROM THE GREAT LAKES THROUGH NORTHERN NEW YORK AND NORTHERN NEW ENGLAND THROUGH TONIGHT. A MUCH STRONGER STORM WILL MOVE OUT OF THE OHIO VALLEY SUNDAY ALONG THIS FRONT. IN ITS WAKE COLDER AIR WILL FILER BACK INTO THE REGION FOR THE FIRST HALF OF THE WEEK. THE WEEKEND WILL FEATURE MILD TEMPERATURES FOR DECEMBER...PERIODS OF RAIN BECOMING WIDESPREAD LATE SATURDAY INTO SUNDAY WITH FREEZING RAIN ALONG THE NORTHERN TIER OF NEW YORK AND NEW ENGLAND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1218 AM EST...BATCH OF RAIN IS NOW EXITING SOUTHERN VERMONT...WITH JUST VERY LIGHT SPRINKLES AND RAIN SHOWERS REMAINING OVER EASTERN NY. THIS LOOKS TO BE A BREAK IN THE PRECIP...AS DEPICTED BY THE HRRR AND LOCAL HIRES WRF. ADDITIONAL RAINFALL...NOTED ON THE REGIONAL MOSAIC RADAR ACROSS WESTERN NEW YORK...WILL BE APPROACHING FOR THE LATE OVERNIGHT HOURS...SO WILL CONTINUE WITH RATHER HIGH POPS ACROSS NORTHERN PARTS OF THE AREA. TEMPERATURES ARE STILL ABOVE FREEZING ACROSS MUCH OF THE AREA EXCEPT FOR A LIMITED AREA OF FAR NORTHERN WARREN AND WASHINGTON COUNTIES WHERE NORTHERLY WINDS HAVE ALLOWED COLD AIR TO DRAIN SOUTHWARD THROUGH THE CHAMPLAIN VALLEY TO THE LAKE GEORGE REGION. TEMPS IN THE NORTHERN PART OF THE LAKE GEORGE AREA ARE IN THE MID TO UPPER 20S...WITH LOW TO MID 30S ACROSS SOUTHERN PARTS OF THE LAKE. A FREEZING RAIN ADVISORY REMAINS IN EFFECT THERE THROUGH 6 AM. WILL CONTINUE TO MENTION UP TO ONE TENTH OF AN INCH OF ICE IN THIS SMALL AREA. TEMPS SHOULD GRADUALLY WARM UP THROUGH THE NIGHT IN THIS AREA. FOR SOME AREAS WHERE MIXING HAS BEEN ABLE TO OCCUR...TEMPS HAVE RISEN INTO THE LOWER TO MID 40S. TEMPERATURES ARE GENERALLY EXPECTED TO REMAIN STEADY THROUGH THE NIGHT FOR THE REMAINDER OF THE AREA. STRONGER UPPER LEVEL ENERGY...FORCING AND MOISTURE ADVECTION APPROACHES SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON. HEAVIER RAINFALL SHOULD SPREAD ACROSS THE REGION SATURDAY AFTERNOON AND NIGHT...WITH THE HEAVIEST RAIN OCCURRING SATURDAY NIGHT INTO EARLY SUNDAY. THERE ARE CONSIDERABLE DISAGREEMENTS IN SOURCES OF GUIDANCE AND ENSEMBLES AS TO HOW MUCH COLDER AIR SINKS SOUTH SATURDAY NIGHT IN RESPONSE TO ENHANCED UPPER CONFLUENCE IN CANADA AS UPPER ENERGY TRACKS WELL NORTH OF THE U.S. CANADIAN BORDER. ENOUGH COLD AIR COULD SINK SOUTHWARD AGAIN SATURDAY NIGHT TO PRODUCE SOME FREEZING RAIN. MODELS INDICATE THAT ANY PERIOD OF NEAR OR BELOW FREEZING TEMPS ALONG THE NORTHERN BORDER OF THE FORECAST AREA WOULD BE BRIEF AND ONLY PRODUCE LIGHT ICING AMOUNTS (UNDER A QUARTER OF AN INCH). NO WINTER STORM WATCH WILL BE ISSUED AND IF APPEARS MORE CERTAIN THAT SOME FREEZING RAIN WILL FALL LATE SATURDAY NIGHT...THEN ADVISORIES CAN BE ISSUED ON SATURDAY. A VERY STRONG BOUNDARY LAYER JET SEGMENT AND ISENTROPIC LIFT...ALONG WITH ANOMALOUSLY HIGH PWAT...SHOULD SUPPORT A HEAVY RAIN EVENT...AND COMBINED WITH SNOW MELT...COULD RESULT IN SOME FLOODING POTENTIAL. THIS WILL BE ADDRESSED IN THE HWO AS RAINFALL FORECASTS FROM SOURCES OF GUIDANCE AND ENSEMBLES STILL INDICATE THAT A BROAD RANGE AND AXIS OF HEAVIEST RAIN COULD FALL NORTH OF WHERE MAXIMUM SNOW MELT OCCURS. A WEST TO SOUTHWEST BOUNDARY LAYER FLOW USUALLY RESULTS IN THE HEAVIEST PRECIPITATION IN THE ADIRONDACKS...WHICH AGAIN MAY SEE THE LEAST WARM TEMPERATURES AND LEAST SNOW MELT. SO...STILL HOLDING OFF ON ANY FLOOD WATCHES. HIGHS SATURDAY IN THE 40S TO LOWER 50S...LOWS SATURDAY IN THE 40S OVER THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA...AND 30S NORTH. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... BY SUNDAY MORNING STATIONARY FRONT REMAINS DRAPED FROM SW NYS TO NR PWM. OVERRUNNING HAD BEEN THE PRIMARY DRIVER OF UVM AND PCPN THROUGH SAT NT ALONG WITH AGEO CIRC ASSOC WITH RIGHT ENTRANCE RGN OF INTENSE 300HPA JET. RAINS WILL HAVE OVERSPREAD THE ENTIRE FCA MUCH OF THE NIGHT. BY SUN MRNG GFS HAS OVER 2 IN QPF IN ADIRONDACKS TO LESS THAN 1 TENTH IN MID HUD VLY WITH A SOMEWHAT MORE GENEROUS MAX IN THE NAM OF 2.6 IN. SUNDAY A SHARP SHORT WV EJECTS INTO THE UPR MIDWEST...TRIGGERING A MUCH DEEPER CYCLOGENISUS IN THE OHIO VLY THAN THE WAVES THAT HAD BEEN RIPPLING ALONG THE STATIONARY FRONT TO THIS POINT. THE LOW DEEPENS AS IT MOVES ACROSS FCA SUN. IN ADDITION THE PREVIOUSLY ACTING ISENTROPIC LIFT AND JET DYNAMICS...CONVERGENCE WITH THE LOW AND ALONG THE WMFNT WILL ENHANCE A BURST OF PCPN SUN WORKING WITH RICH AIR MASS AND PW OF 1.25 IN OR BETTER. SUNDAY THE MDLS DUMP ANOTHER TENTH OF AN INCH QPF IN MID HUD VLY WITH ANOTHER TO 1.25 INCHES IN ADRNDKS. THE GEM HAS SIMILAR NUMBERS WITH A MAX SHIFTED SLIGHTLY TO THE N OF US MDLS AND A FRONTAL POSITION 50 OR SO MILES N. IN SUMMARY QPF VALUES FM DETERMINISTIC MDLS ARE ANOTHER 0.5 TO 1.0 INCHES GREATER THAN PVS QPF. TOTALS ARE ON THE ORDER FROM 0.25 MID HUD VLY TO 3 PLUS INCHES IN ADRNDKS. THE ECMWF AND GEM ARE ON THE LIGHTER SIDE WITH A MAX QPF CLOSER TO 2 INCHES TOTAL. ADD TO THAT THE SNOW PACK MELT. BY SUNDAY SNOW PACK WILL BE RIPE OR RIPENING N. MOST WILL BE GONE IN THE SE. IN THE SE 1.0 LIQ OF SNOW PACK AND A HALF AN INCH OF QPF SHOULDN`T PUSH RIVERS OUT OF THEIR BANKS. HWVR FURTHER N...COLDER TEMPS EARLIER IN THE PERIOD HAVE SLOWED SNOW MELT...WILL GIVE WAY TO 40S SUN WITH 2-3 INCHES OF QPF..AND MAYBE AN INCH OF SNOW MELT. AT THIS POINT AN LEANING TWRD A FLOOD WATCH FOR SAT NT THROUGH SUN...WITH 2-3 IN QPF N TIER...AN INCH OF SNOW MELT. POTENTIAL FOR WIDESPREAD MINOR FLOODING INCRG. BY SUN NT SFC LOW EXISTS NY INTO N NEW ENG AND DRY SLOT MOVES INTO RGN. RN SHOULD DIM TO SCT -SHRA BUT TEMPS WILL REMAIN ABV FREEZING ACROSS MOST AREA...AND SNOW MELT AND RUNOFF WILL CONTINUE. DURING SUNDAY AND SUN NT TEMPS ARE EITHER NON DIURNAL OR MAV/MET MAX MIN VALUES ARE 24 HRS VALUES FM SAT AND WILL USE 3 HRLY TEMPS MONDAY THE SFC LOW AND ITS CDFNT MOVE EAST OF RGN. AND DURING MON AND TUE CAA AND INCRG WIND GRADIENT WILL BE THE RULE AS TEMPS RETURN TO NR OR BLO NORMAL TUES. MON FCA WILL BE IN DRY SLOT WITH VERY GRADUAL CAA. HWVR AT 500HPA MAJOR TROF IS BEING CARVED OUT OVER GRTLKS AS SERIES OF SHORT WVS DIG S INTO IT. MONDAY NGT AND TUES THE 500HPA TROF MOVES ACROSS FCA WITH MUCH STRONGER CDFNT AND BRISK N-NE WINDS IN ITS WAKE. CDFNT PASSAGE WILL TRIGGER SCT -SHSN MON NT...BUT H850 AND LLVL FLOW NOT FAVORABLE FOR LK RESPONSE IN FCA TUE. TUES AND CHRISTMAS TEMPS WILL BE SVRL DEG BLO NORMAL AS SFC HIGH BEGINS BUILDING SE FM OTTAWA VLY. 500HPA TROF MAY STILL BE SUF TO TRIGGER SCT INSTAB -SHSN TUES AND TUE NT. SKIES WILL BE PC WITH MORE CLOUDS N AND FEWER S MON-TUE. CHRISTMAS DAY SHOULD BE BRIGHTER AND SUNNY AS SFC HIGH CRESTS OVER THE REGION, HWVR IT WILL START ON THE FRIGID SIDE AS CLR SKIES ON SOME OF THE LONGEST NIGHTS OF THE YEAR WILL ALLOW IDEAL RADIATIONAL COOLING. MEX LOWS AT SLK ARE -19F TO +10 AT POU. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... DRY CONDITIONS SHOULD PERSIST WEDNESDAY NIGHT...ALTHOUGH A BIT OF A SOUTHERLY GRADIENT DEVELOPS AROUND THE DEPARTING HIGH WHICH COULD ALLOW FOR MILDER TEMPERATURES DEPENDING ON THE AMOUNT OF MIXING AT NIGHT. THE FORECAST BECOMES A BIT MORE MURKY FROM THURSDAY INTO FRIDAY...AS ENERGY ASSOCIATED WITH AN UPPER LEVEL TROUGH MOVES EASTWARD ACROSS THE GREAT LAKES...WHILE THERE IS THE POTENTIAL FOR A SOUTHERN STREAM DISTURBANCE TO PHASE WITH THE PRIMARY TROUGH. THE ECMWF IS MOST AGGRESSIVE WITH THIS SCENARIO...WHICH COULD LEAD TO A MORE WIDESPREAD MODERATE PRECIP EVENT. THE GFS IS MUCH MORE PROGRESSIVE THOUGH...SO WILL CONSERVATIVELY MENTION LOW CHANCE POPS AT THIS TIME. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... IFR CONDITIONS DUE TO RAIN AND FOG CONTINUE TO KGFL AND THIS LOOKS TO CONTINUE FOR THE REMAINDER OF THE OVERNIGHT HOURS. MEANWHILE...VFR CONDITIONS ARE IN PLACE FOR THE OTHER REMAINING TAF SITES...WITH CIGS GENERALLY 4-8 KFT. CIGS WILL GRADUALLY LOWER TO MVFR FOR KALB/KPSF TOWARDS DAYBREAK...ESP AS THE NEXT BATCH OF RAIN CURRENTLY OVER WESTERN NY APPROACHES THE REGION. KPSF/KPOU SHOULD BE ABLE TO AVOID MOST OF THIS NEXT BATCH OF RAIN...WITH MAINLY KGFL/KALB TO BE IMPACTED. DURING THE DAY SATURDAY...CONDITIONS WILL LOWER TO IFR FOR ALL SITES WITH RAIN...MIST...AND LOW STRATUS CLOUDS. IT MAY TAKE UNTIL LATE IN THE DAY FOR THE RAIN TO REACH KPOU. THE STEADIEST AND HEAVIEST RAIN LOOKS TO OCCUR SAT EVENING INTO SAT NIGHT. LLWS WILL BE IN PLACE THROUGH MUCH OF THE TAF PERIOD WITH 2 KFT WINDS AROUND 35-40 KTS OUT OF THE WEST-SOUTHWEST. MEANWHILE...SFC WINDS WILL BE MAINLY LIGHT OVERNIGHT INTO THE DAY SATURDAY...BECOMING SOUTHERLY AT 10 KTS OR LESS. LLWS SHOULD END BY SAT AFTN AS THE BEST LOW LEVEL JET SHIFTS AWAY FROM THE AREA. OUTLOOK... SATURDAY NIGHT: HIGH OPERATIONAL IMPACT. DEFINITE RA. SUNDAY: HIGH OPERATIONAL IMPACT. LIKELY RA. SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA. MONDAY: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN. MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHSN. TUESDAY: LOW OPERATIONAL IMPACT.BREEZY ISOLATED SHSN. TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX. && .HYDROLOGY... MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THROUGH THE WEEKEND...WHICH MEANS SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A STORM SYSTEM MOVING ALONG A FRONTAL BOUNDARY MAY BRING SIGNIFICANT PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY. TEMPERATURES SUNDAY ARE EXPECTED TO WARM INTO THE 50S OR POSSIBLY EVEN 60S ACROSS THE EASTERN CATSKILLS...MID HUDSON VALLEY...CENTRAL AND SOUTHERN TACONICS INTO THE BERKSHIRES AND ACROSS LITCHFIELD COUNTY WITH 50S ACROSS THE CAPITAL REGION...40S FURTHER NORTH. BETWEEN THE RAIN AND RUNOFF FROM SNOWMELT DUE TO THE MILD/WARM TEMPERATURES...SOME FLOODING COULD BE A PROBLEM INCLUDING ICE JAMS ISSUES. AT THIS POINT...WE BELIEVE MOST IF NOT ALL OF THE SNOW COULD BE MELTED FROM ABOUT THE MOHAWK RIVER SOUTH. FURTHER NORTH... TEMPERATURES MIGHT NOT BE WARM ENOUGH TO MELT ALL OF THE SNOW. THE POTENTIAL IS THERE FOR 1-2.5 INCHES OF RAINFALL FROM ALBANY NORTHWARD...POSSIBLY SOME AREAS REACHING 3 INCHES. LESSER AMOUNTS OF RAIN LOOK TO FALL SOUTH OF THE CAPITAL REGION...AN INCH OR LESS. WILL KEEP MENTION OF IN OUR HAZARDOUS WEATHER OUTLOOK. 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...FREEZING RAIN ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR NYZ042-043. MA...NONE. VT...NONE. && $$ SYNOPSIS...GJM/SNYDER NEAR TERM...FRUGIS/GJM/JPV SHORT TERM...SNYDER LONG TERM...JPV AVIATION...FRUGIS HYDROLOGY...GJM/NAS
AREA FORECAST DISCUSSION
NWS ALBANY NY
1218 AM EST SAT DEC 21 2013 .SYNOPSIS... A NEARLY STATIONARY FRONT FROM THE GREAT LAKES THROUGH NORTHERN NEW YORK AND NORTHERN NEW ENGLAND WILL PRODUCE SCATTERED LIGHT PRECIPITATION TONIGHT. THE FRONT WILL SINK SOUTH AS A COLD FRONT INTO PARTS OF CENTRAL NEW YORK AND SOUTHERN VERMONT BY SATURDAY NIGHT...SUPPORTING CHANCES FOR FREEZING RAIN IN THE NORTH COUNTRY. STRONG LOW PRESSURE WILL TRACK NORTHEAST OUT OF THE TENNESSEE AND OHIO VALLEY SUNDAY AS THE FRONT SURGES NORTH INTO CANADA. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1218 AM EST...BATCH OF RAIN IS NOW EXITING SOUTHERN VERMONT...WITH JUST VERY LIGHT SPRINKLES AND RAIN SHOWERS REMAINING OVER EASTERN NY. THIS LOOKS TO BE A BREAK IN THE PRECIP...AS DEPICTED BY THE HRRR AND LOCAL HIRES WRF. ADDITIONAL RAINFALL...NOTED ON THE REGIONAL MOSAIC RADAR ACROSS WESTERN NEW YORK...WILL BE APPROACHING FOR THE LATE OVERNIGHT HOURS...SO WILL CONTINUE WITH RATHER HIGH POPS ACROSS NORTHERN PARTS OF THE AREA. TEMPERATURES ARE STILL ABOVE FREEZING ACROSS MUCH OF THE AREA EXCEPT FOR A LIMITED AREA OF FAR NORTHERN WARREN AND WASHINGTON COUNTIES WHERE NORTHERLY WINDS HAVE ALLOWED COLD AIR TO DRAIN SOUTHWARD THROUGH THE CHAMPLAIN VALLEY TO THE LAKE GEORGE REGION. TEMPS IN THE NORTHERN PART OF THE LAKE GEORGE AREA ARE IN THE MID TO UPPER 20S...WITH LOW TO MID 30S ACROSS SOUTHERN PARTS OF THE LAKE. A FREEZING RAIN ADVISORY REMAINS IN EFFECT THERE THROUGH 6 AM. WILL CONTINUE TO MENTION UP TO ONE TENTH OF AN INCH OF ICE IN THIS SMALL AREA. TEMPS SHOULD GRADUALLY WARM UP THROUGH THE NIGHT IN THIS AREA. FOR SOME AREAS WHERE MIXING HAS BEEN ABLE TO OCCUR...TEMPS HAVE RISEN INTO THE LOWER TO MID 40S. TEMPERATURES ARE GENERALLY EXPECTED TO REMAIN STEADY THROUGH THE NIGHT FOR THE REMAINDER OF THE AREA. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/... STRONGER UPPER LEVEL ENERGY...FORCING AND MOISTURE ADVECTION APPROACHES SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON. HEAVIER RAINFALL SHOULD SPREAD ACROSS THE REGION SATURDAY AFTERNOON AND NIGHT...WITH THE HEAVIEST RAIN OCCURRING SATURDAY NIGHT INTO EARLY SUNDAY. THERE ARE CONSIDERABLE DISAGREEMENTS IN SOURCES OF GUIDANCE AND ENSEMBLES AS TO HOW MUCH COLDER AIR SINKS SOUTH SATURDAY NIGHT IN RESPONSE TO ENHANCED UPPER CONFLUENCE IN CANADA AS UPPER ENERGY TRACKS WELL NORTH OF THE U.S. CANADIAN BORDER. ENOUGH COLD AIR COULD SINK SOUTHWARD AGAIN SATURDAY NIGHT TO PRODUCE SOME FREEZING RAIN. MODELS INDICATE THAT ANY PERIOD OF NEAR OR BELOW FREEZING TEMPS ALONG THE NORTHERN BORDER OF THE FORECAST AREA WOULD BE BRIEF AND ONLY PRODUCE LIGHT ICING AMOUNTS (UNDER A QUARTER OF AN INCH). NO WINTER STORM WATCH WILL BE ISSUED AND IF APPEARS MORE CERTAIN THAT SOME FREEZING RAIN WILL FALL LATE SATURDAY NIGHT...THEN ADVISORIES CAN BE ISSUED ON SATURDAY. A VERY STRONG BOUNDARY LAYER JET SEGMENT AND ISENTROPIC LIFT...ALONG WITH ANOMALOUSLY HIGH PWAT...SHOULD SUPPORT A HEAVY RAIN EVENT...AND COMBINED WITH SNOW MELT...COULD RESULT IN SOME FLOODING POTENTIAL. THIS WILL BE ADDRESSED IN THE HWO AS RAINFALL FORECASTS FROM SOURCES OF GUIDANCE AND ENSEMBLES STILL INDICATE THAT A BROAD RANGE AND AXIS OF HEAVIEST RAIN COULD FALL NORTH OF WHERE MAXIMUM SNOW MELT OCCURS. A WEST TO SOUTHWEST BOUNDARY LAYER FLOW USUALLY RESULTS IN THE HEAVIEST PRECIPITATION IN THE ADIRONDACKS...WHICH AGAIN MAY SEE THE LEAST WARM TEMPERATURES AND LEAST SNOW MELT. SO...STILL HOLDING OFF ON ANY FLOOD WATCHES. HIGHS SATURDAY IN THE 40S TO LOWER 50S...LOWS SATURDAY IN THE 40S OVER THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA...AND 30S NORTH. HIGHS SUNDAY 45 TO 55 NORTH...AND 55 TO 65 SOUTH. LOWS SUNDAY NIGHT IN THE 40S SOUTH...30S NORTH. && .LONG TERM /MONDAY THROUGH FRIDAY/... THE PERIOD STARTS OUT ON MONDAY WITH COLDER AIR GRADUALLY FILTERING INTO THE REGION WITH A WSW FLOW BECOMING WNW. A FRONTAL BOUNDARY TO OUR SOUTH OVER THE MID ATLANTIC REGION IS FORECAST TO STALL...WITH A WAVE OF LOW PRESSURE MOVING NORTHEASTWARD ALONG THE FRONT. SOME LIGHT RAIN ASSOCIATED WITH THIS WAVE COULD AFFECT AREAS MAINLY SOUTH AND EAST OF ALBANY. THE GFS/ECMWF HAS SOME LIGHT QPF JUST SCRAPING OUR SOUTHEAST ZONES...WHILE THE NAM IS MOST AGGRESSIVE WITH BRINGING THE WAVE AND ASSOCIATED QPF NORTHWARD. WILL MENTION CHANCE POPS FOR NOW...WITH ANOTHER AREA OF CHANCE POPS ACROSS NORTHWEST AREAS DUE TO SOME LAKE ENHANCED/UPSLOPE SNOW SHOWERS DEVELOPING. TEMPERATURES SHOULD DROP SIGNIFICANTLY MONDAY NIGHT INTO CHRISTMAS EVE MORNING...AS STRONG COLD ADVECTION COMMENCES. THE FLOW TRAJECTORY IS FORECAST TO SHIFT TO THE NORTHWEST...SO SOME MULTI-BAND LAKE EFFECT SNOW SHOWERS COULD IMPACT THE MOHAWK AND SCHOHARIE VALLEY...AS WELL AS THE NORTHERN CATSKILLS CHRISTMAS EVE DAY. CHRISTMAS EVE NIGHT THROUGH CHRISTMAS DAY LOOKS TO BE DRY BUT COLD REGION-WIDE...AS HIGH PRESSURE BUILDS IN THEN SHIFTS EASTWARD INTO NEW ENGLAND BY LATE CHRISTMAS DAY. DRY CONDITIONS SHOULD PERSIST WEDNESDAY NIGHT...ALTHOUGH A BIT OF A SOUTHERLY GRADIENT DEVELOPS AROUND THE DEPARTING HIGH WHICH COULD ALLOW FOR MILDER TEMPERATURES DEPENDING ON THE AMOUNT OF MIXING AT NIGHT. THE FORECAST BECOMES A BIT MORE MURKY FROM THURSDAY INTO FRIDAY...AS ENERGY ASSOCIATED WITH AN UPPER LEVEL TROUGH MOVES EASTWARD ACROSS THE GREAT LAKES...WHILE THERE IS THE POTENTIAL FOR A SOUTHERN STREAM DISTURBANCE TO PHASE WITH THE PRIMARY TROUGH. THE ECMWF IS MOST AGGRESSIVE WITH THIS SCENARIO...WHICH COULD LEAD TO A MORE WIDESPREAD MODERATE PRECIP EVENT. THE GFS IS MUCH MORE PROGRESSIVE THOUGH...SO WILL CONSERVATIVELY MENTION LOW CHANCE POPS AT THIS TIME. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... IFR CONDITIONS DUE TO RAIN AND FOG CONTINUE TO KGFL AND THIS LOOKS TO CONTINUE FOR THE REMAINDER OF THE OVERNIGHT HOURS. MEANWHILE...VFR CONDITIONS ARE IN PLACE FOR THE OTHER REMAINING TAF SITES...WITH CIGS GENERALLY 4-8 KFT. CIGS WILL GRADUALLY LOWER TO MVFR FOR KALB/KPSF TOWARDS DAYBREAK...ESP AS THE NEXT BATCH OF RAIN CURRENTLY OVER WESTERN NY APPROACHES THE REGION. KPSF/KPOU SHOULD BE ABLE TO AVOID MOST OF THIS NEXT BATCH OF RAIN...WITH MAINLY KGFL/KALB TO BE IMPACTED. DURING THE DAY SATURDAY...CONDITIONS WILL LOWER TO IFR FOR ALL SITES WITH RAIN...MIST...AND LOW STRATUS CLOUDS. IT MAY TAKE UNTIL LATE IN THE DAY FOR THE RAIN TO REACH KPOU. THE STEADIEST AND HEAVIEST RAIN LOOKS TO OCCUR SAT EVENING INTO SAT NIGHT. LLWS WILL BE IN PLACE THROUGH MUCH OF THE TAF PERIOD WITH 2 KFT WINDS AROUND 35-40 KTS OUT OF THE WEST-SOUTHWEST. MEANWHILE...SFC WINDS WILL BE MAINLY LIGHT OVERNIGHT INTO THE DAY SATURDAY...BECOMING SOUTHERLY AT 10 KTS OR LESS. LLWS SHOULD END BY SAT AFTN AS THE BEST LOW LEVEL JET SHIFTS AWAY FROM THE AREA. OUTLOOK... SATURDAY NIGHT: HIGH OPERATIONAL IMPACT. DEFINITE RA. SUNDAY: HIGH OPERATIONAL IMPACT. LIKELY RA. SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA. MONDAY: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN. MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHSN. TUESDAY: LOW OPERATIONAL IMPACT.BREEZY ISOLATED SHSN. TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX. && .HYDROLOGY... MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THROUGH THE WEEKEND...WHICH MEANS SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A STORM SYSTEM MOVING ALONG A FRONTAL BOUNDARY MAY BRING SIGNIFICANT PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY. TEMPERATURES SUNDAY ARE EXPECTED TO WARM INTO THE 50S OR POSSIBLY EVEN 60S ACROSS THE EASTERN CATSKILLS...MID HUDSON VALLEY...CENTRAL AND SOUTHERN TACONICS INTO THE BERKSHIRES AND ACROSS LITCHFIELD COUNTY WITH 50S ACROSS THE CAPITAL REGION...40S FURTHER NORTH. BETWEEN THE RAIN AND RUNOFF FROM SNOWMELT DUE TO THE MILD/WARM TEMPERATURES...SOME FLOODING COULD BE A PROBLEM INCLUDING ICE JAMS ISSUES. AT THIS POINT...WE BELIEVE MOST IF NOT ALL OF THE SNOW COULD BE MELTED FROM ABOUT THE MOHAWK RIVER SOUTH. FURTHER NORTH... TEMPERATURES MIGHT NOT BE WARM ENOUGH TO MELT ALL OF THE SNOW. THE POTENTIAL IS THERE FOR 1-2.5 INCHES OF RAINFALL FROM ALBANY NORTHWARD...POSSIBLY SOME AREAS REACHING 3 INCHES. LESSER AMOUNTS OF RAIN LOOK TO FALL SOUTH OF THE CAPITAL REGION...AN INCH OR LESS. WILL KEEP MENTION OF IN OUR HAZARDOUS WEATHER OUTLOOK. 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...FREEZING RAIN ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR NYZ042-043. MA...NONE. VT...NONE. && $$ SYNOPSIS...GJM NEAR TERM...FRUGIS/GJM/JPV SHORT TERM...GJM LONG TERM...JPV AVIATION...FRUGIS HYDROLOGY...GJM/NAS
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
851 AM EST SAT DEC 21 2013 .SYNOPSIS... HIGH PRESSURE OFF THE COAST WILL CIRCULATE WARM AND INCREASINGLY MOIST AIR INTO THE FORECAST AREA AHEAD OF A SLOW MOVING COLD FRONT. THE FRONT WILL MOVE THROUGH THE FORECAST AREA MONDAY. COOL AND DRY HIGH PRESSURE BEHIND THE FRONT WILL DOMINATE TUESDAY AND WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... INCREASED LOW-LEVEL MOISTURE ASSOCIATED WITH THE SOUTHERLY FLOW ON THE BACKSIDE OF THE OFFSHORE HIGH PLUS NOCTURNAL COOLING HAS HELPED CAUSE AREAS OF STRATUS AND FOG THIS MORNING. HEATING AND MIXING LATER THIS MORNING SHOULD HELP DIMINISH THE LOW CLOUDINESS... BUT SOME CLOUDINESS SHOULD LINGER THROUGH THE DAY BECAUSE OF ISENTROPIC LIFT AND CONTINUED UPPER-LEVEL MOISTURE STREAMING INTO THE AREA IN THE SOUTHWEST FLOW. GENERALLY EXPECT PARTLY CLOUDY OR MOSTLY CLOUDY SKIES. THE LIFT WILL BE WEAK AND MOISTURE SHALLOW WITH FORCING ASSOCIATED WITH THE FRONT WELL TO THE WEST. THE SHOWER CHANCE SHOULD BE LOW. THE HIGH-RESOLUTION MODELS KEEP THE FORECAST AREA DRY. IT WILL BE WARM AND THE TEMPERATURE GUIDANCE WAS CONSISTENT DISPLAYING HIGHS IN THE MIDDLE AND UPPER 70S WHICH WILL BE 15 TO 20 DEGREES ABOVE NORMAL. THE BUFKIT MOMENTUM TRANSFER TOOL AND HRRR INDICATED WIND GUSTS NEAR 20 KNOTS THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... TONIGHT...WE WILL REMAIN IN THE SOUTHERLY FLOW ASSOCIATED WITH THE OFFSHORE HIGH AND COLD FRONT TO OUR WEST. THE MODELS KEEP ISENTROPIC LIFT WEAK AND MOISTURE SHALLOW. ALL OF THE NAM AND GFS MOS SUPPORT VERY LOW POPS. WE USED THE WARMER TEMPERATURE GUIDANCE BECAUSE OF CLOUDINESS AND MIXING. THESE TEMPERATURES WILL BE 20 TO 30 DEGREES ABOVE NORMAL. THE WARMEST DAILY MINIMUM RECORDS FOR THE DATE WILL BE IN JEOPARDY. SUNDAY THROUGH MONDAY NIGHT...SURFACE LOW PRESSURE WILL LIFT NORTHEASTWARD INTO THE GREAT LAKE REGION AND NORTHEAST STATES SUNDAY AND SUNDAY NIGHT. THE TRAILING COLD FRONT WILL MAKE SLOW PROGRESS EASTWARD AND TOWARD THE FORECAST AREA BECAUSE OF SOUTHWESTERLY UPPER-LEVEL FLOW NEARLY PARALLEL TO THE ORIENTATION OF THE FRONT. STRONG WARM ADVECTION WITH SOUTHWEST H85 WINDS OF 40 TO 45 KNOTS WILL HELP SUPPORT NEAR-RECORD HIGH TEMPERATURES SUNDAY WITH MAXIMUM READINGS IN THE MID TO UPPER 70S. THE TIMING OF THE FRONT AND ASSOCIATED PRECIPITATION MAY IMPACT TEMPERATURES MAINLY IN THE WEST PART OF THE FORECAST AREA SUNDAY. A SURGE OF MOISTURE ALONG THE FRONT AIDED BY THE H85 JET WILL RAISE PRECIPITABLE WATER VALUES TO NEAR 1.7 OF AN INCH ACCORDING TO THE NAM...WHICH IS EXTREMELY HIGH FOR THIS TIME OF YEAR. STRONG UPPER DYNAMICS WILL ACCOMPANY THE FRONT AS THE REGION FALLS WITHIN THE RIGHT ENTRANCE REGION OF THE H25 JET. THIS LIFT COMBINED WITH THE MOISTURE AND POTENTIAL INSTABILITY WILL BRING THE POSSIBLY OF HEAVY RAIN AND SEVERE WEATHER SUNDAY EVENING AND OVERNIGHT. THE FRONT WILL BE SLOW TO PUSH ACROSS THE REGION UNTIL THE UPPER FLOW BECOMES MORE WESTERLY WHICH SHOULD OCCUR MONDAY...AS THE UPPER TROUGH TO THE WEST SHIFTS EASTWARD ACROSS THE OHIO AND TENNESSEE VALLEYS. WILL CARRY CATEGORICAL POPS DURING THE SUNDAY NIGHT AND EARLY MONDAY TIME FRAME. BELIEVE MOST OF THE FORECAST AREA WILL SEE SIGNIFICANT RAINFALL SUNDAY NIGHT AND MONDAY. THE NAM INDICATED TOTALS ABOUT 0.6 OF AN INCH AND GFS NEAR 1 INCH. THE 03Z SREF MEAN WAS AROUND 1.2 OF AN INCH. WE AVERAGED THIS GUIDANCE FOR THE RAINFALL FORECAST. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE MONDAY BECAUSE OF EXPECTED CLOUDINESS AND RAIN PLUS COLD ADVECTION BEHIND THE FRONT LATER IN THE DAY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... THE EXTENDED FORECAST FEATURES DRY AND COOL WEATHER FOR CHRISTMAS EVE AND CHRISTMAS DAY FOLLOWED BY INCREASING MOISTURE AND CHANCES FOR RAIN BY THE END OF THE WEEK. THE MEDIUM-RANGE MODELS ARE IN FAIR AGREEMENT SHOWING GENERALLY ZONAL FLOW TUESDAY AND WEDNESDAY WITH AN 1035 MB SURFACE HIGH PRESSURE SYSTEM SETTLING OVER THE MID ATLANTIC AND SOUTHEASTERN STATES. PRECIPITABLE WATER VALUES FALL BELOW A QUARTER OF AN INCH TUESDAY AND WEDNESDAY AND WILL NOT CARRY ANY POPS DURING THIS TIME. THE COOL AND DRY AIR MASS UNDER HIGH PRESSURE WILL YIELD MAXIMUM TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL IN THE 50S WHILE LOW TEMPERATURES WILL BE SOME 5 TO 10 DEGREES BELOW NORMAL WEDNESDAY MORNING AND A FEW DEGREES BELOW NORMAL THURSDAY MORNING. DEEP UPPER-LEVEL TROUGHING ACROSS THE MIDDLE PART OF THE COUNTRY THURSDAY INTO FRIDAY IS EXPECTED TO RESULT IN THE DEVELOPMENT OF A PRESSURE TROUGH OFF THE SOUTHEAST COAST. THERE HAS BEEN MODEL INCONSISTENCIES WITH THE STRENGTH AND LOCATION OF THE TROUGH AND ITS ASSOCIATED MOISTURE. WE FORECASTED SLIGHT CHANCE POPS THURSDAY INTO FRIDAY WHICH WAS SUPPORTED BY THE GFS ENSEMBLE MEAN POP PLUS THE GFS AND ECMWF MOS. TEMPERATURES FOR THE END OF THE WEEK SHOULD BE NEAR NORMAL. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS FOR MUCH OF THE PERIOD...GIVING WAY TO MVFR/IFR CONDITIONS AFTER 22/02Z. PATCHY FOG DEVELOPED OVERNIGHT...HOWEVER WITH THICKENING MID AND UPPER LEVEL CLOUDS MIGRATING INTO THE AREA THE FOG HAS LESSENED OVER THE PAST COUPLE OF HOURS. EXPECT VFR CONDITIONS RETURNING TO ALL TAF SITES BY 15Z. MOISTURE WILL CONTINUE TO INCREASE THROUGH THE AFTERNOON HOURS WITH CLOUDS CONTINUING TO THICKEN AND LOWER. BY 22/02Z EXPECT CIGS TO BEGIN RAPIDLY LOWERING WITH MVFR EXPECTED WITH FURTHER LOWERING TO IFR BETWEEN 22/06 AND 22/08Z. WINDS WILL BE SOUTHERLY AROUND 8 KNOTS THROUGH THE PERIOD. EXTENDED AVIATION OUTLOOK...CIG/VSBY RESTRICTIONS IN FOG/STRATUS EXPECTED INTO EARLY SUNDAY MORNING. A COLD FRONT WILL CROSS THE REGION LATE SUNDAY INTO MONDAY BRINGING SHOWERS...POSSIBLY THUNDERSTORMS...AND ASSOCIATED RESTRICTIONS. && .CLIMATE... COLUMBIA RECORD HIGH TODAY 12/21/13...76 LAST SET IN 1998 RECORD HIGH MINIMUM TONIGHT 12/22/13...60 SET IN 1918 RECORD HIGH SUNDAY 12/22/13...76 LAST SET IN 2011 AUGUSTA BUSH RECORD HIGH TODAY 12/21/13...79 SET IN 1998 RECORD HIGH MINIMUM TONIGHT 12/22/13...59 SET IN 1898 RECORD HIGH SUNDAY 12/22/13...77 SET IN 2011 && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
649 AM EST SAT DEC 21 2013 .SYNOPSIS... HIGH PRESSURE OFF THE COAST WILL CIRCULATE WARM AND INCREASINGLY MOIST AIR INTO THE FORECAST AREA AHEAD OF A SLOW MOVING COLD FRONT. THE FRONT WILL MOVE THROUGH THE FORECAST AREA MONDAY. COOL AND DRY HIGH PRESSURE BEHIND THE FRONT WILL DOMINATE TUESDAY AND WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... INCREASED LOW-LEVEL MOISTURE ASSOCIATED WITH THE SOUTHERLY FLOW ON THE BACKSIDE OF THE OFFSHORE HIGH PLUS NOCTURNAL COOLING HAS HELPED CAUSE AREAS OF STRATUS AND FOG EARLY THIS MORNING. HEATING AND MIXING LATER THIS MORNING SHOULD HELP DIMINISH THE LOW CLOUDINESS... BUT SOME CLOUDINESS SHOULD LINGER THROUGH THE DAY BECAUSE OF ISENTROPIC LIFT AND CONTINUED UPPER-LEVEL MOISTURE STREAMING INTO THE AREA IN THE SOUTHWEST FLOW. GENERALLY EXPECT PARTLY CLOUDY OR MOSTLY CLOUDY SKIES. THE LIFT WILL BE WEAK AND MOISTURE SHALLOW WITH FORCING ASSOCIATED WITH THE FRONT WELL TO THE WEST. THE SHOWER CHANCE SHOULD BE LOW. THE HIGH-RESOLUTION MODELS KEEP THE FORECAST AREA DRY. THE NAM...GFS AND ECMWF MOS INDICATE POPS OF 20 PERCENT OR LESS. IT WILL BE WARM AND THE TEMPERATURE GUIDANCE WAS CONSISTENT DISPLAYING HIGHS IN THE MIDDLE AND UPPER 70S WHICH WILL BE 15 TO 20 DEGREES ABOVE NORMAL. THE BUFKIT MOMENTUM TRANSFER TOOL AND HRRR INDICATED WIND GUSTS NEAR 20 KNOTS THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... TONIGHT...WE WILL REMAIN IN THE SOUTHERLY FLOW ASSOCIATED WITH THE OFFSHORE HIGH AND COLD FRONT TO OUR WEST. THE MODELS KEEP ISENTROPIC LIFT WEAK AND MOISTURE SHALLOW. ALL OF THE NAM AND GFS MOS SUPPORT VERY LOW POPS. WE USED THE WARMER TEMPERATURE GUIDANCE BECAUSE OF CLOUDINESS AND MIXING. THESE TEMPERATURES WILL BE 20 TO 30 DEGREES ABOVE NORMAL. THE WARMEST DAILY MINIMUM RECORDS FOR THE DATE WILL BE IN JEOPARDY. SUNDAY THROUGH MONDAY NIGHT...SURFACE LOW PRESSURE WILL LIFT NORTHEASTWARD INTO THE GREAT LAKE REGION AND NORTHEAST STATES SUNDAY AND SUNDAY NIGHT. THE TRAILING COLD FRONT WILL MAKE SLOW PROGRESS EASTWARD AND TOWARD THE FORECAST AREA BECAUSE OF SOUTHWESTERLY UPPER-LEVEL FLOW NEARLY PARALLEL TO THE ORIENTATION OF THE FRONT. STRONG WARM ADVECTION WITH SOUTHWEST H85 WINDS OF 40 TO 45 KNOTS WILL HELP SUPPORT NEAR-RECORD HIGH TEMPERATURES SUNDAY WITH MAXIMUM READINGS IN THE MID TO UPPER 70S. THE TIMING OF THE FRONT AND ASSOCIATED PRECIPITATION MAY IMPACT TEMPERATURES MAINLY IN THE WEST PART OF THE FORECAST AREA SUNDAY. A SURGE OF MOISTURE ALONG THE FRONT AIDED BY THE H85 JET WILL RAISE PRECIPITABLE WATER VALUES TO NEAR 1.7 OF AN INCH ACCORDING TO THE NAM...WHICH IS EXTREMELY HIGH FOR THIS TIME OF YEAR. STRONG UPPER DYNAMICS WILL ACCOMPANY THE FRONT AS THE REGION FALLS WITHIN THE RIGHT ENTRANCE REGION OF THE H25 JET. THIS LIFT COMBINED WITH THE MOISTURE AND POTENTIAL INSTABILITY WILL BRING THE POSSIBLY OF HEAVY RAIN AND SEVERE WEATHER SUNDAY EVENING AND OVERNIGHT. THE FRONT WILL BE SLOW TO PUSH ACROSS THE REGION UNTIL THE UPPER FLOW BECOMES MORE WESTERLY WHICH SHOULD OCCUR MONDAY...AS THE UPPER TROUGH TO THE WEST SHIFTS EASTWARD ACROSS THE OHIO AND TENNESSEE VALLEYS. WILL CARRY CATEGORICAL POPS DURING THE SUNDAY NIGHT AND EARLY MONDAY TIME FRAME. BELIEVE MOST OF THE FORECAST AREA WILL SEE SIGNIFICANT RAINFALL SUNDAY NIGHT AND MONDAY. THE NAM INDICATED TOTALS ABOUT 0.6 OF AN INCH AND GFS NEAR 1 INCH. THE 03Z SREF MEAN WAS AROUND 1.2 OF AN INCH. WE AVERAGED THIS GUIDANCE FOR THE RAINFALL FORECAST. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE MONDAY BECAUSE OF EXPECTED CLOUDINESS AND RAIN PLUS COLD ADVECTION BEHIND THE FRONT LATER IN THE DAY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... THE EXTENDED FORECAST FEATURES DRY AND COOL WEATHER FOR CHRISTMAS EVE AND CHRISTMAS DAY FOLLOWED BY INCREASING MOISTURE AND CHANCES FOR RAIN BY THE END OF THE WEEK. THE MEDIUM-RANGE MODELS ARE IN FAIR AGREEMENT SHOWING GENERALLY ZONAL FLOW TUESDAY AND WEDNESDAY WITH AN 1035 MB SURFACE HIGH PRESSURE SYSTEM SETTLING OVER THE MID ATLANTIC AND SOUTHEASTERN STATES. PRECIPITABLE WATER VALUES FALL BELOW A QUARTER OF AN INCH TUESDAY AND WEDNESDAY AND WILL NOT CARRY ANY POPS DURING THIS TIME. THE COOL AND DRY AIR MASS UNDER HIGH PRESSURE WILL YIELD MAXIMUM TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL IN THE 50S WHILE LOW TEMPERATURES WILL BE SOME 5 TO 10 DEGREES BELOW NORMAL WEDNESDAY MORNING AND A FEW DEGREES BELOW NORMAL THURSDAY MORNING. DEEP UPPER-LEVEL TROUGHING ACROSS THE MIDDLE PART OF THE COUNTRY THURSDAY INTO FRIDAY IS EXPECTED TO RESULT IN THE DEVELOPMENT OF A PRESSURE TROUGH OFF THE SOUTHEAST COAST. THERE HAS BEEN MODEL INCONSISTENCIES WITH THE STRENGTH AND LOCATION OF THE TROUGH AND ITS ASSOCIATED MOISTURE. WE FORECASTED SLIGHT CHANCE POPS THURSDAY INTO FRIDAY WHICH WAS SUPPORTED BY THE GFS ENSEMBLE MEAN POP PLUS THE GFS AND ECMWF MOS. TEMPERATURES FOR THE END OF THE WEEK SHOULD BE NEAR NORMAL. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS FOR MUCH OF THE PERIOD...GIVING WAY TO MVFR/IFR CONDITIONS AFTER 22/02Z. PATCHY FOG DEVELOPED OVERNIGHT...HOWEVER WITH THICKENING MID AND UPPER LEVEL CLOUDS MIGRATING INTO THE AREA THE FOG HAS LESSENED OVER THE PAST COUPLE OF HOURS. EXPECT REMAINING FOG TO DISSIPATE WITH SUNRISE AND ALL SITES RETURNING TO VFR BY 13Z. MOISTURE WILL CONTINUE TO INCREASE THROUGH THE AFTERNOON HOURS WITH CLOUDS CONTINUING TO THICKEN AND LOWER. BY 22/02Z EXPECT CIGS TO BEGIN RAPIDLY LOWERING WITH MVFR EXPECTED WITH FURTHER LOWERING TO IFR BETWEEN 22/06 AND 22/08Z. WINDS WILL BE SOUTHERLY AROUND 8 KNOTS THROUGH THE PERIOD. EXTENDED AVIATION OUTLOOK...CIG/VSBY RESTRICTIONS IN FOG/STRATUS EXPECTED INTO EARLY SUNDAY MORNING. A COLD FRONT WILL CROSS THE REGION LATE SUNDAY INTO MONDAY BRINGING SHOWERS...POSSIBLY THUNDERSTORMS...AND ASSOCIATED RESTRICTIONS. && .CLIMATE... COLUMBIA RECORD HIGH TODAY 12/21/13...76 LAST SET IN 1998 RECORD HIGH MINIMUM TONIGHT 12/22/13...60 SET IN 1918 RECORD HIGH SUNDAY 12/22/13...76 LAST SET IN 2011 AUGUSTA BUSH RECORD HIGH TODAY 12/21/13...79 SET IN 1998 RECORD HIGH MINIMUM TONIGHT 12/22/13...59 SET IN 1898 RECORD HIGH SUNDAY 12/22/13...77 SET IN 2011 && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
600 AM EST SAT DEC 21 2013 .SYNOPSIS... HIGH PRESSURE OFF THE COAST WILL CIRCULATE WARM AND INCREASINGLY MOIST AIR INTO THE FORECAST AREA AHEAD OF A SLOW MOVING COLD FRONT. THE FRONT WILL MOVE THROUGH THE FORECAST AREA MONDAY. COOL AND DRY HIGH PRESSURE BEHIND THE FRONT WILL DOMINATE TUESDAY AND WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... INCREASED LOW-LEVEL MOISTURE ASSOCIATED WITH THE SOUTHERLY FLOW ON THE BACKSIDE OF THE OFFSHORE HIGH PLUS NOCTURNAL COOLING HAS HELPED CAUSE AREAS OF STRATUS AND FOG EARLY THIS MORNING. HEATING AND MIXING LATER THIS MORNING SHOULD HELP DIMINISH THE LOW CLOUDINESS... BUT SOME CLOUDINESS SHOULD LINGER THROUGH THE DAY BECAUSE OF ISENTROPIC LIFT AND CONTINUED UPPER-LEVEL MOISTURE STREAMING INTO THE AREA IN THE SOUTHWEST FLOW. GENERALLY EXPECT PARTLY CLOUDY OR MOSTLY CLOUDY SKIES. THE LIFT WILL BE WEAK AND MOISTURE SHALLOW WITH FORCING ASSOCIATED WITH THE FRONT WELL TO THE WEST. THE SHOWER CHANCE SHOULD BE LOW. THE HIGH-RESOLUTION MODELS KEEP THE FORECAST AREA DRY. THE NAM...GFS AND ECMWF MOS INDICATE POPS OF 20 PERCENT OR LESS. IT WILL BE WARM AND THE TEMPERATURE GUIDANCE WAS CONSISTENT DISPLAYING HIGHS IN THE MIDDLE AND UPPER 70S WHICH WILL BE 15 TO 20 DEGREES ABOVE NORMAL. THE BUFKIT MOMENTUM TRANSFER TOOL AND HRRR INDICATED WIND GUSTS NEAR 20 KNOTS THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... TONIGHT...WE WILL REMAIN IN THE SOUTHERLY FLOW ASSOCIATED WITH THE OFFSHORE HIGH AND COLD FRONT TO OUR WEST. THE MODELS KEEP ISENTROPIC LIFT WEAK AND MOISTURE SHALLOW. ALL OF THE NAM AND GFS MOS SUPPORT VERY LOW POPS. WE USED THE WARMER TEMPERATURE GUIDANCE BECAUSE OF CLOUDINESS AND MIXING. THESE TEMPERATURES WILL BE 20 TO 30 DEGREES ABOVE NORMAL. THE WARMEST DAILY MINIMUM RECORDS FOR THE DATE WILL BE IN JEOPARDY. SUNDAY THROUGH MONDAY NIGHT...SURFACE LOW PRESSURE WILL LIFT NORTHEASTWARD INTO THE GREAT LAKE REGION AND NORTHEAST STATES SUNDAY AND SUNDAY NIGHT. THE TRAILING COLD FRONT WILL MAKE SLOW PROGRESS EASTWARD AND TOWARD THE FORECAST AREA BECAUSE OF SOUTHWESTERLY UPPER-LEVEL FLOW NEARLY PARALLEL TO THE ORIENTATION OF THE FRONT. STRONG WARM ADVECTION WITH SOUTHWEST H85 WINDS OF 40 TO 45 KNOTS WILL HELP SUPPORT NEAR-RECORD HIGH TEMPERATURES SUNDAY WITH MAXIMUM READINGS IN THE MID TO UPPER 70S. THE TIMING OF THE FRONT AND ASSOCIATED PRECIPITATION MAY IMPACT TEMPERATURES MAINLY IN THE WEST PART OF THE FORECAST AREA SUNDAY. A SURGE OF MOISTURE ALONG THE FRONT AIDED BY THE H85 JET WILL RAISE PRECIPITABLE WATER VALUES TO NEAR 1.7 OF AN INCH ACCORDING TO THE NAM...WHICH IS EXTREMELY HIGH FOR THIS TIME OF YEAR. STRONG UPPER DYNAMICS WILL ACCOMPANY THE FRONT AS THE REGION FALLS WITHIN THE RIGHT ENTRANCE REGION OF THE H25 JET. THIS LIFT COMBINED WITH THE MOISTURE AND POTENTIAL INSTABILITY WILL BRING THE POSSIBLY OF HEAVY RAIN AND SEVERE WEATHER SUNDAY EVENING AND OVERNIGHT. THE FRONT WILL BE SLOW TO PUSH ACROSS THE REGION UNTIL THE UPPER FLOW BECOMES MORE WESTERLY WHICH SHOULD OCCUR MONDAY...AS THE UPPER TROUGH TO THE WEST SHIFTS EASTWARD ACROSS THE OHIO AND TENNESSEE VALLEYS. WILL CARRY CATEGORICAL POPS DURING THE SUNDAY NIGHT AND EARLY MONDAY TIME FRAME. BELIEVE MOST OF THE FORECAST AREA WILL SEE SIGNIFICANT RAINFALL SUNDAY NIGHT AND MONDAY. THE NAM INDICATED TOTALS ABOUT 0.6 OF AN INCH AND GFS NEAR 1 INCH. THE 03Z SREF MEAN WAS AROUND 1.2 OF AN INCH. WE AVERAGED THIS GUIDANCE FOR THE RAINFALL FORECAST. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE MONDAY BECAUSE OF EXPECTED CLOUDINESS AND RAIN PLUS COLD ADVECTION BEHIND THE FRONT LATER IN THE DAY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... THE EXTENDED FORECAST FEATURES DRY AND COOL WEATHER FOR CHRISTMAS EVE AND CHRISTMAS DAY FOLLOWED BY INCREASING MOISTURE AND CHANCES FOR RAIN BY THE END OF THE WEEK. THE MEDIUM-RANGE MODELS ARE IN FAIR AGREEMENT SHOWING GENERALLY ZONAL FLOW TUESDAY AND WEDNESDAY WITH AN 1035 MB SURFACE HIGH PRESSURE SYSTEM SETTLING OVER THE MID ATLANTIC AND SOUTHEASTERN STATES. PRECIPITABLE WATER VALUES FALL BELOW A QUARTER OF AN INCH TUESDAY AND WEDNESDAY AND WILL NOT CARRY ANY POPS DURING THIS TIME. THE COOL AND DRY AIR MASS UNDER HIGH PRESSURE WILL YIELD MAXIMUM TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL IN THE 50S WHILE LOW TEMPERATURES WILL BE SOME 5 TO 10 DEGREES BELOW NORMAL WEDNESDAY MORNING AND A FEW DEGREES BELOW NORMAL THURSDAY MORNING. DEEP UPPER-LEVEL TROUGHING ACROSS THE MIDDLE PART OF THE COUNTRY THURSDAY INTO FRIDAY IS EXPECTED TO RESULT IN THE DEVELOPMENT OF A PRESSURE TROUGH OFF THE SOUTHEAST COAST. THERE HAS BEEN MODEL INCONSISTENCIES WITH THE STRENGTH AND LOCATION OF THE TROUGH AND ITS ASSOCIATED MOISTURE. WE FORECASTED SLIGHT CHANCE POPS THURSDAY INTO FRIDAY WHICH WAS SUPPORTED BY THE GFS ENSEMBLE MEAN POP PLUS THE GFS AND ECMWF MOS. TEMPERATURES FOR THE END OF THE WEEK SHOULD BE NEAR NORMAL. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... LOW CONFIDENCE REGARDING CIG/VSBY RESTRICTIONS EARLY THIS MORNING. CLOUDS CONTINUE TO INCREASE FROM THE WEST AS WITH PATCHY FOG BEGINNING TO FORM. LOW AND MID CLOUDS HAVE MOVED INTO EASTERN GA WHICH WILL WORK TO LESSEN FOG POTENTIAL...HOWEVER WITH FOG ALREADY DEVELOPING POTENTIAL FOR FOG REMAINS MODERATE AND THUS CONFIDENCE REMAINS LOW DUE TO TIMING ISSUES. HAVE REMAINED WITH MVFR FOG FOR CAE/CUB/DNL WITH IFR/LIFR FOR AGS/OGB. FOG WILL ERODE AFTER SUNRISE AND ONSET OF MIXING WITH REMAINDER OF THE PERIOD VFR. WINDS WILL BE LIGHT AND VARIABLE THROUGH MID MORNING THEN BECOME SOUTHWESTERLY AROUND 10 KNOTS THROUGH THE END OF THE PERIOD. EXTENDED AVIATION OUTLOOK...CIG/VSBY RESTRICTIONS IN FOG/STRATUS EXPECTED LATE SATURDAY NIGHT INTO EARLY SUNDAY MORNING. A COLD FRONT WILL CROSS THE REGION LATE SUNDAY INTO MONDAY BRINGING SHOWERS...POSSIBLY THUNDERSTORMS...AND ASSOCIATED RESTRICTIONS. && .CLIMATE... COLUMBIA RECORD HIGH TODAY 12/21/13...76 LAST SET IN 1998 RECORD HIGH MINIMUM TONIGHT 12/22/13...60 SET IN 1918 RECORD HIGH SUNDAY 12/22/13...76 LAST SET IN 2011 AUGUSTA BUSH RECORD HIGH TODAY 12/21/13...79 SET IN 1998 RECORD HIGH MINIMUM TONIGHT 12/22/13...59 SET IN 1898 RECORD HIGH SUNDAY 12/22/13...77 SET IN 2011 && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
340 AM EST SAT DEC 21 2013 .SYNOPSIS... HIGH PRESSURE OFF THE COAST WILL CIRCULATE WARM AND INCREASINGLY MOIST AIR INTO THE FORECAST AREA AHEAD OF A SLOW MOVING COLD FRONT. THE FRONT WILL MOVE THROUGH THE FORECAST AREA MONDAY. COOL AND DRY HIGH PRESSURE BEHIND THE FRONT WILL DOMINATE TUESDAY AND WEDNESDAY. && .NEAR TERM /THROUGH TODAY/... INCREASED LOW-LEVEL MOISTURE ASSOCIATED WITH THE SOUTHERLY FLOW ON THE BACKSIDE OF THE OFFSHORE HIGH PLUS NOCTURNAL COOLING SHOULD HELP SUPPORT CONSIDERABLE STRATUS AND FOG EARLY THIS MORNING. STRATUS SHOULD BE FAVORED BECAUSE OF SIGNIFICANT BOUNDARY-LAYER WIND. HEATING AND MIXING LATER THIS MORNING SHOULD HELP DIMINISH SOME OF THIS CLOUDINESS...BUT CLOUDINESS SHOULD LINGER THROUGH THE DAY BECAUSE OF ISENTROPIC LIFT AND CONTINUED UPPER-LEVEL MOISTURE STREAMING INTO THE AREA IN THE SOUTHWEST FLOW. GENERALLY EXPECT PARTLY CLOUDY OR MOSTLY CLOUDY SKIES. THE LIFT WILL BE WEAK AND MOISTURE SHALLOW WITH FORCING ASSOCIATED WITH THE FRONT WELL TO THE WEST. THE SHOWER CHANCE SHOULD BE LOW. THE HIGH-RESOLUTION MODELS KEEP THE FORECAST AREA DRY. THE NAM...GFS AND ECMWF MOS INDICATE POPS OF 20 PERCENT OR LESS. IT WILL BE WARM AND THE TEMPERATURE GUIDANCE WAS CONSISTENT DISPLAYING HIGHS IN THE MIDDLE AND UPPER 70S WHICH WILL BE 15 TO 20 DEGREES ABOVE NORMAL. THE BUFKIT MOMENTUM TRANSFER TOOL AND HRRR INDICATED WIND GUSTS NEAR 20 KNOTS THIS AFTERNOON. && .SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... TONIGHT...WE WILL REMAIN IN THE SOUTHERLY FLOW ASSOCIATED WITH THE OFFSHORE HIGH AND COLD FRONT TO OUR WEST. THE MODELS KEEP ISENTROPIC LIFT WEAK AND MOISTURE SHALLOW. ALL OF THE NAM AND GFS MOS SUPPORT VERY LOW POPS. WE USED THE WARMER TEMPERATURE GUIDANCE BECAUSE OF CLOUDINESS AND MIXING. THESE TEMPERATURES WILL BE 20 TO 30 DEGREES ABOVE NORMAL. THE WARMEST DAILY MINIMUM RECORDS FOR THE DATE WILL BE IN JEOPARDY. SUNDAY THROUGH MONDAY NIGHT...SURFACE LOW PRESSURE WILL LIFT NORTHEASTWARD INTO THE GREAT LAKE REGION AND NORTHEAST STATES SUNDAY AND SUNDAY NIGHT. THE TRAILING COLD FRONT WILL MAKE SLOW PROGRESS EASTWARD AND TOWARD THE FORECAST AREA BECAUSE OF SOUTHWESTERLY UPPER-LEVEL FLOW NEARLY PARALLEL TO THE ORIENTATION OF THE FRONT. STRONG WARM ADVECTION WITH SOUTHWEST H85 WINDS OF 40 TO 45 KNOTS WILL HELP SUPPORT NEAR-RECORD HIGH TEMPERATURES SUNDAY WITH MAXIMUM READINGS IN THE MID TO UPPER 70S. THE TIMING OF THE FRONT AND ASSOCIATED PRECIPITATION MAY IMPACT TEMPERATURES MAINLY IN THE WEST PART OF THE FORECAST AREA SUNDAY. A SURGE OF MOISTURE ALONG THE FRONT AIDED BY THE H85 JET WILL RAISE PRECIPITABLE WATER VALUES TO NEAR 1.7 OF AN INCH ACCORDING TO THE NAM...WHICH IS EXTREMELY HIGH FOR THIS TIME OF YEAR. STRONG UPPER DYNAMICS WILL ACCOMPANY THE FRONT AS THE REGION FALLS WITHIN THE RIGHT ENTRANCE REGION OF THE H25 JET. THIS LIFT COMBINED WITH THE MOISTURE AND POTENTIAL INSTABILITY WILL BRING THE POSSIBLY OF HEAVY RAIN AND SEVERE WEATHER SUNDAY EVENING AND OVERNIGHT. THE FRONT WILL BE SLOW TO PUSH ACROSS THE REGION UNTIL THE UPPER FLOW BECOMES MORE WESTERLY WHICH SHOULD OCCUR MONDAY...AS THE UPPER TROUGH TO THE WEST SHIFTS EASTWARD ACROSS THE OHIO AND TENNESSEE VALLEYS. WILL CARRY CATEGORICAL POPS DURING THE SUNDAY NIGHT AND EARLY MONDAY TIME FRAME. BELIEVE MOST OF THE FORECAST AREA WILL SEE SIGNIFICANT RAINFALL SUNDAY NIGHT AND MONDAY. THE NAM INDICATED TOTALS ABOUT 0.6 OF AN INCH AND GFS NEAR 1 INCH. THE 03Z SREF MEAN WAS AROUND 1.2 OF AN INCH. WE AVERAGED THIS GUIDANCE FOR THE RAINFALL FORECAST. LEANED TOWARD THE COOLER TEMPERATURE GUIDANCE MONDAY BECAUSE OF EXPECTED CLOUDINESS AND RAIN PLUS COLD ADVECTION BEHIND THE FRONT LATER IN THE DAY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... THE EXTENDED FORECAST FEATURES DRY AND COOL WEATHER FOR CHRISTMAS EVE AND CHRISTMAS DAY FOLLOWED BY INCREASING MOISTURE AND CHANCES FOR RAIN BY THE END OF THE WEEK. THE MEDIUM-RANGE MODELS ARE IN FAIR AGREEMENT SHOWING GENERALLY ZONAL FLOW TUESDAY AND WEDNESDAY WITH AN 1035 MB SURFACE HIGH PRESSURE SYSTEM SETTLING OVER THE MID ATLANTIC AND SOUTHEASTERN STATES. PRECIPITABLE WATER VALUES FALL BELOW A QUARTER OF AN INCH TUESDAY AND WEDNESDAY AND WILL NOT CARRY ANY POPS DURING THIS TIME. THE COOL AND DRY AIR MASS UNDER HIGH PRESSURE WILL YIELD MAXIMUM TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL IN THE 50S WHILE LOW TEMPERATURES WILL BE SOME 5 TO 10 DEGREES BELOW NORMAL WEDNESDAY MORNING AND A FEW DEGREES BELOW NORMAL THURSDAY MORNING. DEEP UPPER-LEVEL TROUGHING ACROSS THE MIDDLE PART OF THE COUNTRY THURSDAY INTO FRIDAY IS EXPECTED TO RESULT IN THE DEVELOPMENT OF A PRESSURE TROUGH OFF THE SOUTHEAST COAST. THERE HAS BEEN MODEL INCONSISTENCIES WITH THE STRENGTH AND LOCATION OF THE TROUGH AND ITS ASSOCIATED MOISTURE. WE FORECASTED SLIGHT CHANCE POPS THURSDAY INTO FRIDAY WHICH WAS SUPPORTED BY THE GFS ENSEMBLE MEAN POP PLUS THE GFS AND ECMWF MOS. TEMPERATURES FOR THE END OF THE WEEK SHOULD BE NEAR NORMAL. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... LOW CONFIDENCE REGARDING CIG/VSBY RESTRICTIONS LATE TONIGHT/EARLY SATURDAY MORNING. CLOUDS CONTINUE TO INCREASE FROM THE WEST AS WITH PATCHY FOG BEGINNING TO FORM. LOW AND MID CLOUDS HAVE MOVED INTO EASTERN GA WHICH WILL WORK TO LESSEN FOG POTENTIAL OVERNIGHT...HOWEVER WITH FOG ALREADY DEVELOPING POTENTIAL FOR FOG REMAINS MODERATE AND THUS CONFIDENCE REMAINS LOW DUE TO TIMING ISSUES. HAVE REMAINED WITH MVFR FOG FOR CAE/CUB/DNL WITH IFR/LIFR FOR AGS/OGB. FOG WILL ERODE WITH SUNRISE AND ONSET OF MIXING WITH REMAINDER OF THE PERIOD VFR. WINDS WILL BE LIGHT AND VARIABLE THROUGH MID MORNING THEN BECOME SOUTHWESTERLY AROUND 10 KNOTS THROUGH THE END OF THE PERIOD. EXTENDED AVIATION OUTLOOK...CIG/VSBY RESTRICTIONS IN FOG/STRATUS EXPECTED LATE SATURDAY NIGHT INTO EARLY SUNDAY MORNING. A COLD FRONT WILL CROSS THE REGION LATE SUNDAY INTO MONDAY BRINGING SHOWERS...POSSIBLY THUNDERSTORMS...AND ASSOCIATED RESTRICTIONS. && .CLIMATE COLUMBIA RECORD HIGH TODAY 12/21/13...76 LAST SET IN 1998 RECORD HIGH MINIMUM TONIGHT 12/22/13...60 SET IN 1918 RECORD HIGH SUNDAY 12/22/13...76 LAST SET IN 2011 AUGUSTA BUSH RECORD HIGH TODAY 12/21/13...79 SET IN 1998 RECORD HIGH MINIMUM TONIGHT 12/22/13...59 SET IN 1898 RECORD HIGH SUNDAY 12/22/13...77 SET IN 2011 && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
858 PM CST SUN DEC 22 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 03Z... * MVFR CEILING TRENDS. * A BRIEF PERIOD OF LIGHT SNOW THIS EVENING WITH 5-7SM VSBYS BETWEEN ABOUT 03-05Z. * CHANCE OF LIGHT SNOW OR FLURRIES MONDAY AFTN/EVENING. RATZER //DISCUSSION...UPDATED 00Z... MAIN AVIATION FORECAST CONCERNS ARE MVFR CEILINGS THIS EVENING AND CEILING TRENDS THROUGH MONDAY...IN ADDITION TO THE POTENTIAL FOR A PERIOD OF LIGHT SNOW THIS EVENING AND ANOTHER MONDAY AFTERNOON/EVENING. LOW PRESSURE ASSOCIATED WITH THE OVERNIGHT/EARLY MORNING STORM SYSTEM CONTINUES TO WEAKEN AS IT PULLS AWAY ACROSS THE EASTERN GREAT LAKES REGION. A SERIES OF WEAKER DISTURBANCES WILL MAINTAIN UPPER LEVEL TROUGHING ACROSS THE REGION THROUGH MONDAY NIGHT HOWEVER...WITH AN EXTENSIVE AREA OF MVFR CLOUDS LINGERING ALONG AND EAST OF THE MISSISSIPPI RIVER. ONE MID-LEVEL DISTURBANCE OVER MN/IA PER SATELLITE IMAGERY WAS PRODUCING A NORTH-SOUTH BAND OF LIGHT SNOW OVER PORTIONS OF WISCONSIN AND NORTHWEST IL EARLY THIS EVENING...AND THOUGH RADAR TRENDS AND SFC VISIBILITY REPORTS INDICATE DECREASING INTENSITY IT DOES APPEAR THAT A PERIOD OF LIGHT SNOW WILL AFFECT KRFD FROM ROUGHLY 00-02Z...AND CHICAGO AREA TERMINALS ROUGHLY 02-04Z THIS EVENING WITH PERHAPS A BRIEF 4-6SM VSBY REDUCTION. OTHERWISE...MAINLY JUST A FEW FLURRIES EXPECTED OVERNIGHT...WITH MVFR CIGS GENERALLY 1100-1800 FT. MODEL GUIDANCE AND NORTHWEST CLOUD-LEVEL WINDS WOULD SUPPORT A CONTINUATION OF MVFR CIGS BLO 2000 FT...THOUGH SOME IMPROVEMENT TO HIGH-MVFR OR EVEN VFR IS POSSIBLE EARLY MONDAY MORNING AS MID- LEVELS DRY AND A BRIEF PERIOD OF SUBSIDENCE OCCURS BETWEEN TONIGHTS DISTURBANCE AND ANOTHER WHICH WILL MOVE INTO THE AREA MONDAY AFTERNOON. THIS NEXT STRONGER DISTURBANCE MAY BRING ANOTHER PERIOD OF LIGHT SNOW TO THE TERMINALS MONDAY AFTERNOON/EVENING... THOUGH DRY MID/UPPER LEVELS SUGGEST MAINLY LIGHT SNOW SHOWERS OR FLURRIES. WINDS...SURFACE LOW PRESSURE TROUGH WILL LINGER ACROSS WISCONSIN IN RESPONSE TO UPPER LEVEL DISTURBANCES THROUGH THE PERIOD...WHILE HIGH PRESSURE RIDGE BUILDS ACROSS THE LOWER MISSOURI AND OHIO VALLEYS TO OUR SOUTHWEST. THIS WILL MAINTAIN WEST WINDS ACROSS THE AREA THROUGH MONDAY...WITH A MODEST PRESSURE GRADIENT AND STEEPENING LOW LEVEL LAPSE RATES WITH COLD AIR ADVECTION PRODUCING SOME GUSTS INTO THE 15-20 KT RANGE MONDAY. RATZER //ORD AND MDW CONFIDENCE...UPDATED 03Z... * HIGH CONFIDENCE IN MVFR CIGS THROUGH THIS EVENING. MEDIUM CONFIDENCE IN CIG TRENDS LATE TONIGHT/MONDAY. * HIGH CONFIDENCE IN LGT SNOW THIS EVENING...LOW CONFIDENCE IN VSBY REDUCTIONS. * MEDIUM CONFIDENCE IN LGT SNOW/FLURRIES MONDAY AFTN/EVE. LOW CONFIDENCE IN CIG/VIS IMPACTS. RATZER //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
  [top] Area Forecast Discussion National Weather Service Lincoln IL 846 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. Smith && .AVIATION... ISSUED 540 PM CST Sun Dec 22 2013 Widespread MVFR and local IFR cigs will prevail over the area thru the evening with a decrease in cloud cover from west to east expected after midnight. Latest satellite data and surface obs indicate the backedge of the clouds were still over parts of central Iowa, so it will take another 6 to 8 hours before we see a marked improvement in our area. Once we see the cloud band to shift off to our east Monday morning, sct-bkn VFR cigs are expected thereafter. Surface winds will remain out of the west to northwest at 10 to 15 kts thru the period. 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 CHICAGO/ROMEOVILLE IL
307 AM CST SAT DEC 21 2013 .DISCUSSION... 744 PM CST THE FREEZING RAIN ADVISORY FOR NORTH CENTRAL AND EXTREME NORTHEAST ILLINOIS WAS ALLOWED TO EXPIRE. FREEZING RAIN HAD DIMINISHED TO FREEZING DRIZZLE EARLY THIS EVENING AND HAS NOW ENDED ACROSS MOST OF THE ADVISORY AREA. THERE MAY BE A LINGERING PATCH OR TWO OF FREEZING DRIZZLE BUT THOSE TOO ARE EXPECTED TO END VERY SHORTLY. RADARS AT MKX...DVN AND ARX HAVE ALL SHOWN A W TO E CLEARING OF THE WEAK ECHOES WHILE AN AREA OF WEAK ECHOES ASSOCIATED WITH SOME DRIZZLE AND LIGHT RAIN HAD BLOSSOMED OVERHEAD BUT IS STEADILY MOVING TO THE E SO THIS PRECIP IS EXPECTED TO END 9PM CST AS THE TAIL END OF THE LATEST MINOR SHORT WAVE TROUGH MOVES E OF THE AREA. FORTUNATELY WHERE THIS PRECIP IS OCCURRING SURFACE TEMPERATURES ARE ABOVE FREEZING. THE LAKE AND PORTER INDIANA COUNTIES PORTION OF THE DENSE FOG ADVISORY ALSO WAS ALLOWED TO EXPIRE AS THE FRONTAL BOUNDARY HAD DRIFTED SLIGHTLY SOUTHWARD ALLOWING WINDS TO BECOME LIGHT NORTHWEST AND VISIBILITIES TO IMPROVER ABOVE DENSE FOG CRITERIA. THE REMAINDER OF THE DENSE FOG ADVISORY HAS BEEN EXTENDED UNTIL 9 PM CST. THE WEAK SURFACE REFLECTION OF THE SHORT WAVE WAS IN THE VPZ-SBN AREA. AS IT CONTINUES SLOWLY TO THE E THE REST OF THE EVENING THE FRONTAL BOUNDARY WILL CONTINUE TO SAG DEEPER INTO THE AREA THAT REMAINS UNDER THE ADVISORY WITH AN THINNING OF THE DENSE FOG EXPECTED TO OCCUR. TRS //PREV DISCUSSION... 337 PM CST...INCLUDING UPDATED WINTER STORM DISCUSSION BELOW... TONIGHT THROUGH SATURDAY MORNING... 325 PM CST... TONIGHT...THE FREEZING RAIN ADVISORY CONTINUES THROUGH 7 PM FOR FAR NORTHERN IL AS LIGHT SHOWER ACTIVITY AND PATCHY DRIZZLE CONTINUE TO OVERRIDE A SUBFREEZING BOUNDARY LAYER. THE GOES WATER VAPOR LOOP SHOWS MODEST DRYING OVER THE AREA IN THE MID- LEVELS...BUT JUST ENOUGH WEAK ASCENT APPEARS TO BE PRESENT WITHIN THE LOW-LEVEL SATURATION TO KEEP TRIGGERING THESE LIGHT SHOWERS. THE FREEZING DEMARCATION HELD STEADY MUCH OF TODAY FROM NEAR MENDOTA NORTHEAST TO LAKE COUNTY IL. DO NOT SEE MUCH SHIFT WITH THAT THROUGH EARLY THIS EVE. SO WITH IT BEING A BUSY HOLIDAY TRAVEL TIME ADDED TO THE NORMAL FRIDAY COMMUTE...CERTAINLY LET THE ADVISORY CONTINUE TO 7 PM. AS TEMPERATURES SLOWLY FALL BELOW FREEZING SOUTH OF THE ADVISORY...UNTREATED WET ROADWAYS ARE LIKELY TO EXPERIENCE SOME GLAZING TOO. THE DENSE FOG ADVISORY FOR SOUTHERN AREAS SHOULD BE FINE ENDING AT 7 PM AS WINDS BEGIN TO INCREASE BEHIND THE BOUNDARY AND LOWER DEW POINTS SEEP IN. FORCING REMAINS WEAK THROUGH MUCH OF TONIGHT WITH LIMITED MOISTURE TRANSPORT AND REALLY ANY TYPE OF MID-LEVEL WAVE/TRIGGER. SO WHILE THERE IS A CHANCE FOR FREEZING DRIZZLE...ANY PRECIP SHOULD BE PATCHY AT BEST AND LIGHT AFTER 7-8 PM. SATURDAY MORNING...THE RAP AND OTHER HIGH RES GUIDANCE KEY IN ON MOISTURE TRANSPORT AHEAD OF THE MAIN DEVELOPING SYSTEM /DESCRIBED BELOW/ ADVANCING INTO THE SOUTHERN CWA IN THE PRE-DAWN HOURS AND INTO SAT MORNING. THE CONVERGENCE AT THE NOSE OF THIS CREEPS INTO THE SOUTHERN FORECAST AREA IN THE MORNING...WHERE FREEZING DRIZZLE AND RAIN LOOK POSSIBLE...THOUGH THERE COULD BE QUITE A BIT OF RAIN AND CONVECTIVE ACTIVITY ACROSS THE MID-MISSISSIPPI VALLEY THAT MAY HALT THE FRONT EDGE ADVANCE OF THE PRECIP. HAVE CONTINUED MENTION OF LIGHT FREEZING PRECIP SAT MORNING ACROSS AREAS MAINLY SOUTH OF I-80. MTF DISCUSSION ON WINTER STORM. WE HAVE UPGRADED PORTIONS OF THE WINTER STORM WATCH TO WARNING AND CONTINUED THE WATCH FOR LAKE AND KANE COUNTIES. THE VIGOROUS MID LEVEL FEATURE...CURRENTLY NOTED IN WATER VAPOR NEAR THE BAJA OF CALIFORNIA EARLY THIS AFTERNOON IS FORECAST TO TAKE ON A NEGATIVE TILT AS IT MOVES OUT ACROSS THE TEXAS PANHANDLE AROUND MIDDAY ON SATURDAY. THIS FEATURE WILL LIFT QUICKLY NORTH-NORTHEASTWARD ACROSS THE MID MISSISSIPPI VALLEY AND ACROSS NORTHERN ILLINOIS SATURDAY NIGHT. MODEL GUIDANCE CONTINUES TO WAVER AROUND A BIT ON THE ACTUAL TRACK OF THE 850 AND SURFACE LOWS. THEREFORE...I HAVE TRENDED CLOSER TO THE ENSEMBLE MEANS...WHICH TRACK THE 850 LOW RIGHT ACROSS NORTHEASTERN ILLINOIS LATE SATURDAY NIGHT. THIS TRACK FAVORS NORTH CENTRAL AND FAR NORTHEASTERN ILLINOIS FOR THE HEAVIEST SNOWFALL...ESPECIALLY SATURDAY NIGHT INTO EARLY SUNDAY AS STRONG FRONTOGENESIS SETS UP WITHIN THE DEFORMATION ZONE...JUST TO THE NORTH AND WEST OF THE 850 LOW TRACK. THIS WILL LIKELY SUPPORT AN AREA OF HEAVY SNOWFALL ACROSS THESE AREAS...WITH SNOW RATES LIKELY TO REACH OR EVEN EXCEED AN 1 INCH PER HOUR AT TIMES...GIVEN THE GOOD COUPLING OF THE LARGE SCALE FORCING FOR ASCENT FROM THE MID LEVEL WAVE AND THE GOOD FRONTOGENESIS. MID LEVEL LAPSE RATES WILL ALSO SUPPORT GOOD SNOWFALL ACROSS THE WARNING AREAS. I CHOSE TO LEAVE THE WATCH IN PLACE FOR LAKE AND KANE COUNTIES. THESE AREAS MAY ALSO SEE 6+ INCHES OF SNOW...IN PORTIONS OF THE COUNTIES...BUT DUE TO THE POTENTLY FOR SOME SLIGHT SHIFTS YET IN THE TRACK OF THE SYSTEM...WITH A POTENTIAL FOR A FARTHER NORTHWEST TRACK...I CHOOSE TO HOLD OFF. THE OTHER CONCERN IS THE THREAT FOR FREEZING RAIN AND SLEET ACCUMULATIONS...ESPECIALLY ACROSS SOUTHERN SECTIONS OF THE WARNING AREA...AND PLACES TO THE SOUTH. TEMPERATURES ARE EXPECTED TO REMAIN RIGHT AROUND THE FREEZING POINT...SO IT APPEARS THAT ICING AMOUNTS MAY BE LIMITED SOME...ESPECIALLY NEAR CHICAGO. WITH THAT BEING SAID...I STILL THINK THERE IS A DECENT POTENTIAL TO HAVE AN AREA OF SOME ICE ACCUMULATIONS...OF 0.1 TO 0.2 INCHES...PRIMARILY NORTH OF I-80 UP TO AROUND THE I-88 CORRIDOR. CLOSER TO THE LAKE AND THE CITY ICE AMOUNTS MAY BE LESS DUE TO THE FLOW OFF THE LAKE POSSIBLY RESULTING IN TEMPS JUST ABOVE FREEZING. IT APPEARS THE MAIN ICING THREAT WILL NOT OCCUR UNTIL TOMORROW AFTERNOON AND INTO THE EVENING. THEREFORE...WE HAVE SOME TIME TO BETTER IRON OUT THE AREAS MOST SUSCEPTIBLE TO ICING. WE WILL HIGHLIGHT THIS THREAT IN AN SPS. IT ALSO APPEARS THE HEAVY RAIN THREAT WILL MAINLY BE ACROSS MY SOUTHEASTERN COUNTIES...SO NO CHANGES TO THE GOING FLOOD WATCH. STRONG MOISTURE CONVERGENCE AND ANOMALOUSLY HIGH PWATS WILL LIKELY PRODUCE AMOUNTS IN EXCESS OF AN INCH OR SO ACROSS THESE AREAS...AND WITH ALL OF THIS BECOMING RUNOFF...RAPID RISES ON AREA STREAMS ARE EXPECTED. THE SNOW THREAT FOR AREAS SOUTH OF THE CURRENT WARNING AREA APPEAR TO SOMEWHAT LIMITED...WITH A SHARP GRADIENT IN THE SNOW ACCUMULATIONS EXPECTED. AN IMPRESSIVE DRY SLOT WILL PUNCH IN ACROSS THE AREA LATE SATURDAY NIGHT INTO SUNDAY...LIKELY RESULT IN ONLY LIGHT SNOW OR EVEN FZ DRIZZLE GIVEN THE LOSE OF ICE IN THE CLOUDS. TOTAL SNOW AMOUNTS LOOK TO DROP TO UNDER AN INCH BY THE TIME YOU GET CLOSE TO CHICAGO AND INTERSTATE 80. MUCH COLDER AIR SPILLS IN ACROSS THE AREA SUNDAY NIGHT...WITH LIGHT PRECIP CONTINUING IN ASSOCIATION WILL ANOTHER UPPER LEVEL DISTURBANCE. TEMPERATURES WILL LIKELY DROP INTO THE SINGLE DIGITS IN MOST AREAS SUNDAY NIGHT. THUS...ANY STANDING WATER REMAINING...WITH LIKELY QUICKLY FREEZE IN PLACE ACROSS THE AREA. KJB EXTENDED FORECAST PERIOD /MONDAY MORNING THROUGH FRIDAY INCLUDING THE CHRISTMAS HOLIDAY... 300 PM CST... THE SENSIBLE WEATHER WILL QUIET CONSIDERABLY WITH THE MAIN FORECAST CONCERNS FOCUSING ON TEMPERATURES AND THE CHANCE FOR SOME LIGHT SNOW ON CHRISTMAS EVE AND EARLY CHRISTMAS DAY. THE GENERAL TREND FOR THE EXTENDED FORECAST PERIOD WILL BE FOR MUCH BELOW NORMAL TEMPERATURES WITH THE ONLY CHANCE FOR SOME LIGHT SNOW ON CHRISTMAS EVE INTO CHRISTMAS DAY. A HIGH AMPLITUDE LONGWAVE TROUGH IS EXPECTED TO CARVE OUT OVER THE CNTRL CONUS WITH THE TROUGH AXIS EXTENDING FROM HUDSON BAY THROUGH CENTRAL TEXAS. INITIALLY ON MONDAY...THE LOCAL AREA WILL SEE THE TROUGH AXIS MOVING THROUGH THE AREA TRANSITIONING THE REGION FROM RELATIVE WARM ADVECTION TO STRONG COLD ADVECTION. TEMPERATURES WILL DROP OFF QUICKLY BY MONDAY MORNING...WITH LOWS EXPECTED TO DROP ONTO THE SINGLE DIGITS WEST OF THE FOX VALLEY AND I-55 CORRIDOR. LOWS OVER THE EASTERN PORTION OF THE FORECAST AREA SHOULD HANG IN THE MIDDLE TO UPPER TEENS. AS THE LONGWAVE TROUGH CONTINUES TO THE ERN CONUS MONDAY AND MONDAY NIGHT...WEAK UPPER RIDGING WILL BUILD ACROSS THE UPPER MISSISSIPPI VALLEY...WITH THE AMPLITUDE OF THE UPPER LEVEL PATTERN CONTINUING TO AMPLIFY. WITH DEEP LAYER FLOW REMAINING ON THE NWLY FLOW SIDE OF THE UPPER RIDGE...TEMPERATURES WILL CONTINUE TO DROP WITH LOWS TUESDAY MORNING BELOW ZERO OVER MUCH OF THE CWA... GENERALLY WEST OF A LINE FROM WAUKEGAN TO PONTIAC...WITH THE COLDEST AIR OVER THE ROCKFORD AREA WHERE TEMPS SHOULD BOTTOM OUT AT -5F TO -10F. WIND CHILLS WILL BE A CONCERN AS WELL. WITH WINDS OF 5-10 KT LIKELY...WIND CHILLS WILL APPROACH THE -20F WIND CHILL ADVISORY CRITERIA WEST OF THE FOX VALLEY AND I-55 CORRIDOR. BY TUESDAY NIGHT...THE LONGER RANGE MODELS ARE ADVERTISING A PAIR OF NORTHERN STREAM SHORTWAVES TRACKING ACROSS THE NRN PLAINS. THE NRN-MOST WAVE...WHICH IS ALSO THE STRONGER OF THE PAIR...SHOULD TRACK TO THE EAST...ACROSS THE UPPER GREAT LAKES WHILE THE MORE SOUTHERLY...WEAKER WAVE DROPS THROUGH THE NRN PLAINS TO THE MIDDLE MISSISSIPPI VALLEY. THIS THERE IS SOME DISCREPANCY AMONG THE LONGER RANGE GUIDANCE ON THE SPEED OF PROGRESSION OF THIS WAVE...BUT THE GENERAL CONSENSUS IS THAT THE WAVE WILL CROSS THE MIDDLE MISSISSIPPI VALLEY...TRACKING OVER THE IL/WI BOARDER. FOLLOWING A PERIOD OF STRONG COLD/DRY ADVECTION...THERE WILL BE LITTLE IN SITU MOISTURE FOR THE SYSTEM TO WORK WITH AND WILL LARGELY HAVE TO RELY ON DYNAMICS TO PRODUCE ANY PCPN. AT THIS POINT...ANTICIPATE THAT UPPER DYNAMICS SHOULD BE STRONG ENOUGH TO PRODUCE AT LEAST SOME LIGHT SNOW FOR LATE CHRISTMAS EVE INTO EARLY CHRISTMAS DAY. GIVEN THE LACK OF DEEP LAYER MOISTURE OR ANY SIGNIFICANT LOW LEVEL MOISTURE TRANSPORT AS FLOW THROUGH THE LOWER LEVELS SHOULD BE MORE WESTERLY AND UNABLE TO TAP ANY GULF MOISTURE...ANY ACCUMULATIONS WILL LIKELY BE LIGHT. A BRIEF PERIOD OF MORE WLY OR AT LEAST BROAD...FLAT TROUGHING SHOULD COVER THE MIDWEST ON WEDNESDAY...ALLOWING FOR SOME MODERATION OF TEMPERATURES ON WEDNESDAY AND THURSDAY...WITH HIGHS IN THE UPPER 20S TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY. A REINFORCING SHOT OF COLD AIR ASSOCIATED WITH A STRONG NORTHERN STREAM SHORTWAVE DIGGING INTO THE UPPER MISSISSIPPI VALLEY AND SOUTHERN GREAT LAKES WILL BRING SUB-ZERO TEMPERATURES BACK TO MUCH OF THE CWA FOR FRIDAY MORNING. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * LIFR CIGS EXPECTED TO LIFT TO IFR THIS MORNING...WITH SOME CHANCE FOR MVFR DURING THE DAY. * IFR VSBY GRADUALLY IMPROVES TO MVFR THROUGH THE MORNING. * TIMING AND TYPE OF PRECIP ONSET TODAY. * VARIABLE WEST TO NORTHWEST WINDS TURNING NORTHEAST AND INCREASING IN SPEED THROUGH THE MORNING. MDB //DISCUSSION...UPDATED 09Z... VSBY HAS BEGUN TO LEVEL OFF AND EVEN SLIGHTLY IMPROVE WITH VALUES MAINLY IN THE 1-2SM RANGE. EXPECT THAT THERE WILL BE A GRADUAL IMPROVEMENT THIS MORNING WITH SOME SLIGHT LOW LEVEL DRYING TAKING PLACE. HOWEVER...IMPROVEMENT WILL PROBABLY BE STUNTED BY APPROACHING PRECIP INTO THE AFTERNOON. CIGS SHOULD ALSO GRADUALLY IMPROVE BUT CONFIDENCE IN HOW MUCH REMAINS LOW. MDB FROM 06Z... ONE LOW PRESSURE AREA IS OFF TO THE EAST WHILE THE NEXT LOW DEVELOPS OVER SOUTHWEST ARKANSAS. DRIZZLE/FREEZING DRIZZLE HAS DIMINISHED IN COVERAGE DURING THE EVENING BUT VSBY HAS STRUGGLED TO IMPROVE IN MANY AREAS...THOUGH ORD HAS IMPROVED TO GREATER THAN 6SM. SEVERAL SITES HAVE LOST SOME VSBY IN THE LAST HOUR OR SO INCLUDING MDW SO WILL CARRY SOME LOWER VSBY THAN PREVIOUS TAFS TO ACCOUNT FOR THIS. TOUGH TO SAY WHETHER THERE WILL BE MUCH IMPROVEMENT OVERNIGHT DESPITE THE LACK OF DRIZZLE NOW OCCURRING SO FURTHER ADJUSTMENTS MAY BE NEEDED. OTHERWISE EXPECT IFR/LIFR CIGS TO PERSIST THROUGH THE MORNING. THE ARKANSAS LOW WILL MOVE NORTHEAST TODAY SPREADING PRECIPITATION NORTHWARD INTO THE AREA. -DZ/-FZDZ MAY DEVELOP AS UPWARD MOTION BEGINS TO INCREASE MID/LATE MORNING. OTHERWISE CHANCES FOR MIXED PRECIPITATION WILL INCREASE DURING THE AFTERNOON FROM SOUTH TO NORTH...WITH RAIN/SNOW/SLEET ALL POSSIBLE. WITH SURFACE TEMPS RIGHT AROUND FREEZING...SOME FREEZING RAIN MAY ALSO OCCUR. PRECIP INTENSITY MAXIMIZES BY EARLY EVENING WITH WARMER AIR MOVING IN ALOFT FAVORING MORE RAIN AT MDW/GYY WITH RAIN/SLEET POSSIBLE AT ORD/DPA AND A TRANSITION FROM SNOW/SLEET TO SNOW AT RFD WHERE TEMPS ALOFT WILL BE COLDER. DRIER AIR IS FORECAST TO MOVE IN ALOFT DURING THE LATE EVENING HOURS WHICH WOULD LIKELY RESULT IN A LULL IN PRECIP INTENSITY AND FAVOR -DZ/-FZDZ DEPENDING ON SURFACE TEMPERATURE. RFD MAY REMAIN ON THE FRINGE OF THE DRY SLOT ALLOWING FOR FLUCTUATIONS BETWEEN SNOW AND -FZDZ. WEST AND NORTHWEST WINDS WILL TURN NORTHEAST LATER THIS MORNING AND INCREASE IN SPEED INTO THE EVENING. MDB //ORD AND MDW CONFIDENCE...UPDATED 09Z... * MEDIUM CONFIDENCE IN LIFR CIGS LIFTING TO IFR...LOW CONFIDENCE IN POTENTIAL FOR MVFR CIGS TODAY. * MEDIUM-HIGH CONFIDENCE IN IFR VSBY IMPROVING TO MVFR THIS MORNING. * MEDIUM CONFIDENCE IN PRECIP TIMING/TYPE FORECAST. * HIGH CONFIDENCE IN WIND TRENDS. MDB //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...SNOW ESPECIALLY IN THE MORNING. IFR LIKELY. BRIEF LIFR POSSIBLE EARLY. MONDAY...CHANCE OF SNOW SHOWERS. MVFR/IFR POSSIBLE. TUESDAY...VFR. WEDNESDAY...CHANCE OF LIGHT SNOW. MVFR/IFR POSSIBLE. THURSDAY...SLIGHT CHANCE OF LIGHT SNOW. MVFR POSSIBLE. RATZER && .MARINE... 300 AM CST ONE AREA OF LOW PRESSURE HAS DEPARTED TO THE EAST AND IS NOW CROSSING LAKE ERIE. ANOTHER LOW IS DEVELOPING ACROSS WESTERN ARKANSAS AND WILL LIFT NORTHEAST TODAY. THE LOW WILL THEN REACH NORTHERN INDIANA SUNDAY MORNING BEFORE BEGINNING TO WEAKEN AS IT CROSSES NEW ENGLAND SUNDAY EVENING. HIGH PRESSURE WILL MOVE SOUTHWARD ACROSS MANITOBA AND WESTERN ONTARIO TODAY AND WORK WITH THE DEVELOPING LOW TO STRENGTHEN THE PRESSURE GRADIENT ACROSS LAKE MICHIGAN TONIGHT AND SUNDAY MORNING. WINDS WILL TURN NORTHEASTERLY TODAY ACROSS THE LAKE. SPEEDS LOOK TO TOP OUT AROUND 30 KT...BUT CANNOT RULE OUT SOME GALE FORCE GUSTS LATE TONIGHT. WILL GO AHEAD AND HOIST A SMALL CRAFT ADVISORY FOR THE ILLINOIS NEARSHORE WATERS FROM THIS EVENING THROUGH SUNDAY AFTERNOON...AND FOR THE INDIANA NEARSHORE WATERS UNTIL EARLY MONDAY MORNING AS WINDS TURN FROM NORTHEAST TO NORTH AND THEN NORTHWEST. STRONG HIGH PRESSURE WILL THEN SPREAD SOUTHWARD INTO THE MIDWEST AND WESTERN GREAT LAKES MONDAY INTO TUESDAY WITH THE ASSOCIATED RIDGE AXIS CROSSING LAKE MICHIGAN TUESDAY. DIMINISHING WINDS WILL RESULT...BUT SPEEDS WILL INCREASE AS THE DIRECTION TURNS SOUTHERLY TUESDAY NIGHT. LOW PRESSURE IS EXPECTED TO MOVE ACROSS THE CANADIAN PRAIRIES INTO WESTERN ONTARIO WEDNESDAY WITH THE STRENGTH OF THE LOW DICTATING THE POTENTIAL FOR GALES WEDNESDAY. THE LOW WILL PASS LATER WEDNESDAY TURNING WINDS WESTERLY. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010- ILZ011...4 PM SATURDAY TO 10 AM SUNDAY. FREEZING RAIN ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 1 PM SATURDAY. FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 10 PM SATURDAY. WINTER WEATHER ADVISORY...ILZ006-ILZ012...4 PM SATURDAY TO 10 AM SUNDAY. WINTER WEATHER ADVISORY...ILZ019-ILZ020-ILZ021-ILZ022...NOON SATURDAY TO 10 PM SATURDAY. WINTER WEATHER ADVISORY...ILZ013-ILZ014...2 PM SATURDAY TO 10 PM SATURDAY. IN...FREEZING RAIN ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 1 PM SATURDAY. FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 10 PM SATURDAY. 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
NWS CHICAGO/ROMEOVILLE IL
1210 AM CST SAT DEC 21 2013 .DISCUSSION... 744 PM CST THE FREEZING RAIN ADVISORY FOR NORTH CENTRAL AND EXTREME NORTHEAST ILLINOIS WAS ALLOWED TO EXPIRE. FREEZING RAIN HAD DIMINISHED TO FREEZING DRIZZLE EARLY THIS EVENING AND HAS NOW ENDED ACROSS MOST OF THE ADVISORY AREA. THERE MAY BE A LINGERING PATCH OR TWO OF FREEZING DRIZZLE BUT THOSE TOO ARE EXPECTED TO END VERY SHORTLY. RADARS AT MKX...DVN AND ARX HAVE ALL SHOWN A W TO E CLEARING OF THE WEAK ECHOES WHILE AN AREA OF WEAK ECHOES ASSOCIATED WITH SOME DRIZZLE AND LIGHT RAIN HAD BLOSSOMED OVERHEAD BUT IS STEADILY MOVING TO THE E SO THIS PRECIP IS EXPECTED TO END 9PM CST AS THE TAIL END OF THE LATEST MINOR SHORT WAVE TROUGH MOVES E OF THE AREA. FORTUNATELY WHERE THIS PRECIP IS OCCURRING SURFACE TEMPERATURES ARE ABOVE FREEZING. THE LAKE AND PORTER INDIANA COUNTIES PORTION OF THE DENSE FOG ADVISORY ALSO WAS ALLOWED TO EXPIRE AS THE FRONTAL BOUNDARY HAD DRIFTED SLIGHTLY SOUTHWARD ALLOWING WINDS TO BECOME LIGHT NORTHWEST AND VISIBILITIES TO IMPROVER ABOVE DENSE FOG CRITERIA. THE REMAINDER OF THE DENSE FOG ADVISORY HAS BEEN EXTENDED UNTIL 9 PM CST. THE WEAK SURFACE REFLECTION OF THE SHORT WAVE WAS IN THE VPZ-SBN AREA. AS IT CONTINUES SLOWLY TO THE E THE REST OF THE EVENING THE FRONTAL BOUNDARY WILL CONTINUE TO SAG DEEPER INTO THE AREA THAT REMAINS UNDER THE ADVISORY WITH AN THINNING OF THE DENSE FOG EXPECTED TO OCCUR. TRS //PREV DISCUSSION... 337 PM CST...INCLUDING UPDATED WINTER STORM DISCUSSION BELOW... TONIGHT THROUGH SATURDAY MORNING... 325 PM CST... TONIGHT...THE FREEZING RAIN ADVISORY CONTINUES THROUGH 7 PM FOR FAR NORTHERN IL AS LIGHT SHOWER ACTIVITY AND PATCHY DRIZZLE CONTINUE TO OVERRIDE A SUBFREEZING BOUNDARY LAYER. THE GOES WATER VAPOR LOOP SHOWS MODEST DRYING OVER THE AREA IN THE MID- LEVELS...BUT JUST ENOUGH WEAK ASCENT APPEARS TO BE PRESENT WITHIN THE LOW-LEVEL SATURATION TO KEEP TRIGGERING THESE LIGHT SHOWERS. THE FREEZING DEMARCATION HELD STEADY MUCH OF TODAY FROM NEAR MENDOTA NORTHEAST TO LAKE COUNTY IL. DO NOT SEE MUCH SHIFT WITH THAT THROUGH EARLY THIS EVE. SO WITH IT BEING A BUSY HOLIDAY TRAVEL TIME ADDED TO THE NORMAL FRIDAY COMMUTE...CERTAINLY LET THE ADVISORY CONTINUE TO 7 PM. AS TEMPERATURES SLOWLY FALL BELOW FREEZING SOUTH OF THE ADVISORY...UNTREATED WET ROADWAYS ARE LIKELY TO EXPERIENCE SOME GLAZING TOO. THE DENSE FOG ADVISORY FOR SOUTHERN AREAS SHOULD BE FINE ENDING AT 7 PM AS WINDS BEGIN TO INCREASE BEHIND THE BOUNDARY AND LOWER DEW POINTS SEEP IN. FORCING REMAINS WEAK THROUGH MUCH OF TONIGHT WITH LIMITED MOISTURE TRANSPORT AND REALLY ANY TYPE OF MID-LEVEL WAVE/TRIGGER. SO WHILE THERE IS A CHANCE FOR FREEZING DRIZZLE...ANY PRECIP SHOULD BE PATCHY AT BEST AND LIGHT AFTER 7-8 PM. SATURDAY MORNING...THE RAP AND OTHER HIGH RES GUIDANCE KEY IN ON MOISTURE TRANSPORT AHEAD OF THE MAIN DEVELOPING SYSTEM /DESCRIBED BELOW/ ADVANCING INTO THE SOUTHERN CWA IN THE PRE-DAWN HOURS AND INTO SAT MORNING. THE CONVERGENCE AT THE NOSE OF THIS CREEPS INTO THE SOUTHERN FORECAST AREA IN THE MORNING...WHERE FREEZING DRIZZLE AND RAIN LOOK POSSIBLE...THOUGH THERE COULD BE QUITE A BIT OF RAIN AND CONVECTIVE ACTIVITY ACROSS THE MID-MISSISSIPPI VALLEY THAT MAY HALT THE FRONT EDGE ADVANCE OF THE PRECIP. HAVE CONTINUED MENTION OF LIGHT FREEZING PRECIP SAT MORNING ACROSS AREAS MAINLY SOUTH OF I-80. MTF DISCUSSION ON WINTER STORM. WE HAVE UPGRADED PORTIONS OF THE WINTER STORM WATCH TO WARNING AND CONTINUED THE WATCH FOR LAKE AND KANE COUNTIES. THE VIGOROUS MID LEVEL FEATURE...CURRENTLY NOTED IN WATER VAPOR NEAR THE BAJA OF CALIFORNIA EARLY THIS AFTERNOON IS FORECAST TO TAKE ON A NEGATIVE TILT AS IT MOVES OUT ACROSS THE TEXAS PANHANDLE AROUND MIDDAY ON SATURDAY. THIS FEATURE WILL LIFT QUICKLY NORTH-NORTHEASTWARD ACROSS THE MID MISSISSIPPI VALLEY AND ACROSS NORTHERN ILLINOIS SATURDAY NIGHT. MODEL GUIDANCE CONTINUES TO WAVER AROUND A BIT ON THE ACTUAL TRACK OF THE 850 AND SURFACE LOWS. THEREFORE...I HAVE TRENDED CLOSER TO THE ENSEMBLE MEANS...WHICH TRACK THE 850 LOW RIGHT ACROSS NORTHEASTERN ILLINOIS LATE SATURDAY NIGHT. THIS TRACK FAVORS NORTH CENTRAL AND FAR NORTHEASTERN ILLINOIS FOR THE HEAVIEST SNOWFALL...ESPECIALLY SATURDAY NIGHT INTO EARLY SUNDAY AS STRONG FRONTOGENESIS SETS UP WITHIN THE DEFORMATION ZONE...JUST TO THE NORTH AND WEST OF THE 850 LOW TRACK. THIS WILL LIKELY SUPPORT AN AREA OF HEAVY SNOWFALL ACROSS THESE AREAS...WITH SNOW RATES LIKELY TO REACH OR EVEN EXCEED AN 1 INCH PER HOUR AT TIMES...GIVEN THE GOOD COUPLING OF THE LARGE SCALE FORCING FOR ASCENT FROM THE MID LEVEL WAVE AND THE GOOD FRONTOGENESIS. MID LEVEL LAPSE RATES WILL ALSO SUPPORT GOOD SNOWFALL ACROSS THE WARNING AREAS. I CHOSE TO LEAVE THE WATCH IN PLACE FOR LAKE AND KANE COUNTIES. THESE AREAS MAY ALSO SEE 6+ INCHES OF SNOW...IN PORTIONS OF THE COUNTIES...BUT DUE TO THE POTENTLY FOR SOME SLIGHT SHIFTS YET IN THE TRACK OF THE SYSTEM...WITH A POTENTIAL FOR A FARTHER NORTHWEST TRACK...I CHOOSE TO HOLD OFF. THE OTHER CONCERN IS THE THREAT FOR FREEZING RAIN AND SLEET ACCUMULATIONS...ESPECIALLY ACROSS SOUTHERN SECTIONS OF THE WARNING AREA...AND PLACES TO THE SOUTH. TEMPERATURES ARE EXPECTED TO REMAIN RIGHT AROUND THE FREEZING POINT...SO IT APPEARS THAT ICING AMOUNTS MAY BE LIMITED SOME...ESPECIALLY NEAR CHICAGO. WITH THAT BEING SAID...I STILL THINK THERE IS A DECENT POTENTIAL TO HAVE AN AREA OF SOME ICE ACCUMULATIONS...OF 0.1 TO 0.2 INCHES...PRIMARILY NORTH OF I-80 UP TO AROUND THE I-88 CORRIDOR. CLOSER TO THE LAKE AND THE CITY ICE AMOUNTS MAY BE LESS DUE TO THE FLOW OFF THE LAKE POSSIBLY RESULTING IN TEMPS JUST ABOVE FREEZING. IT APPEARS THE MAIN ICING THREAT WILL NOT OCCUR UNTIL TOMORROW AFTERNOON AND INTO THE EVENING. THEREFORE...WE HAVE SOME TIME TO BETTER IRON OUT THE AREAS MOST SUSCEPTIBLE TO ICING. WE WILL HIGHLIGHT THIS THREAT IN AN SPS. IT ALSO APPEARS THE HEAVY RAIN THREAT WILL MAINLY BE ACROSS MY SOUTHEASTERN COUNTIES...SO NO CHANGES TO THE GOING FLOOD WATCH. STRONG MOISTURE CONVERGENCE AND ANOMALOUSLY HIGH PWATS WILL LIKELY PRODUCE AMOUNTS IN EXCESS OF AN INCH OR SO ACROSS THESE AREAS...AND WITH ALL OF THIS BECOMING RUNOFF...RAPID RISES ON AREA STREAMS ARE EXPECTED. THE SNOW THREAT FOR AREAS SOUTH OF THE CURRENT WARNING AREA APPEAR TO SOMEWHAT LIMITED...WITH A SHARP GRADIENT IN THE SNOW ACCUMULATIONS EXPECTED. AN IMPRESSIVE DRY SLOT WILL PUNCH IN ACROSS THE AREA LATE SATURDAY NIGHT INTO SUNDAY...LIKELY RESULT IN ONLY LIGHT SNOW OR EVEN FZ DRIZZLE GIVEN THE LOSE OF ICE IN THE CLOUDS. TOTAL SNOW AMOUNTS LOOK TO DROP TO UNDER AN INCH BY THE TIME YOU GET CLOSE TO CHICAGO AND INTERSTATE 80. MUCH COLDER AIR SPILLS IN ACROSS THE AREA SUNDAY NIGHT...WITH LIGHT PRECIP CONTINUING IN ASSOCIATION WILL ANOTHER UPPER LEVEL DISTURBANCE. TEMPERATURES WILL LIKELY DROP INTO THE SINGLE DIGITS IN MOST AREAS SUNDAY NIGHT. THUS...ANY STANDING WATER REMAINING...WITH LIKELY QUICKLY FREEZE IN PLACE ACROSS THE AREA. KJB EXTENDED FORECAST PERIOD /MONDAY MORNING THROUGH FRIDAY INCLUDING THE CHRISTMAS HOLIDAY... 300 PM CST... THE SENSIBLE WEATHER WILL QUIET CONSIDERABLY WITH THE MAIN FORECAST CONCERNS FOCUSING ON TEMPERATURES AND THE CHANCE FOR SOME LIGHT SNOW ON CHRISTMAS EVE AND EARLY CHRISTMAS DAY. THE GENERAL TREND FOR THE EXTENDED FORECAST PERIOD WILL BE FOR MUCH BELOW NORMAL TEMPERATURES WITH THE ONLY CHANCE FOR SOME LIGHT SNOW ON CHRISTMAS EVE INTO CHRISTMAS DAY. A HIGH AMPLITUDE LONGWAVE TROUGH IS EXPECTED TO CARVE OUT OVER THE CNTRL CONUS WITH THE TROUGH AXIS EXTENDING FROM HUDSON BAY THROUGH CENTRAL TEXAS. INITIALLY ON MONDAY...THE LOCAL AREA WILL SEE THE TROUGH AXIS MOVING THROUGH THE AREA TRANSITIONING THE REGION FROM RELATIVE WARM ADVECTION TO STRONG COLD ADVECTION. TEMPERATURES WILL DROP OFF QUICKLY BY MONDAY MORNING...WITH LOWS EXPECTED TO DROP ONTO THE SINGLE DIGITS WEST OF THE FOX VALLEY AND I-55 CORRIDOR. LOWS OVER THE EASTERN PORTION OF THE FORECAST AREA SHOULD HANG IN THE MIDDLE TO UPPER TEENS. AS THE LONGWAVE TROUGH CONTINUES TO THE ERN CONUS MONDAY AND MONDAY NIGHT...WEAK UPPER RIDGING WILL BUILD ACROSS THE UPPER MISSISSIPPI VALLEY...WITH THE AMPLITUDE OF THE UPPER LEVEL PATTERN CONTINUING TO AMPLIFY. WITH DEEP LAYER FLOW REMAINING ON THE NWLY FLOW SIDE OF THE UPPER RIDGE...TEMPERATURES WILL CONTINUE TO DROP WITH LOWS TUESDAY MORNING BELOW ZERO OVER MUCH OF THE CWA... GENERALLY WEST OF A LINE FROM WAUKEGAN TO PONTIAC...WITH THE COLDEST AIR OVER THE ROCKFORD AREA WHERE TEMPS SHOULD BOTTOM OUT AT -5F TO -10F. WIND CHILLS WILL BE A CONCERN AS WELL. WITH WINDS OF 5-10 KT LIKELY...WIND CHILLS WILL APPROACH THE -20F WIND CHILL ADVISORY CRITERIA WEST OF THE FOX VALLEY AND I-55 CORRIDOR. BY TUESDAY NIGHT...THE LONGER RANGE MODELS ARE ADVERTISING A PAIR OF NORTHERN STREAM SHORTWAVES TRACKING ACROSS THE NRN PLAINS. THE NRN-MOST WAVE...WHICH IS ALSO THE STRONGER OF THE PAIR...SHOULD TRACK TO THE EAST...ACROSS THE UPPER GREAT LAKES WHILE THE MORE SOUTHERLY...WEAKER WAVE DROPS THROUGH THE NRN PLAINS TO THE MIDDLE MISSISSIPPI VALLEY. THIS THERE IS SOME DISCREPANCY AMONG THE LONGER RANGE GUIDANCE ON THE SPEED OF PROGRESSION OF THIS WAVE...BUT THE GENERAL CONSENSUS IS THAT THE WAVE WILL CROSS THE MIDDLE MISSISSIPPI VALLEY...TRACKING OVER THE IL/WI BOARDER. FOLLOWING A PERIOD OF STRONG COLD/DRY ADVECTION...THERE WILL BE LITTLE IN SITU MOISTURE FOR THE SYSTEM TO WORK WITH AND WILL LARGELY HAVE TO RELY ON DYNAMICS TO PRODUCE ANY PCPN. AT THIS POINT...ANTICIPATE THAT UPPER DYNAMICS SHOULD BE STRONG ENOUGH TO PRODUCE AT LEAST SOME LIGHT SNOW FOR LATE CHRISTMAS EVE INTO EARLY CHRISTMAS DAY. GIVEN THE LACK OF DEEP LAYER MOISTURE OR ANY SIGNIFICANT LOW LEVEL MOISTURE TRANSPORT AS FLOW THROUGH THE LOWER LEVELS SHOULD BE MORE WESTERLY AND UNABLE TO TAP ANY GULF MOISTURE...ANY ACCUMULATIONS WILL LIKELY BE LIGHT. A BRIEF PERIOD OF MORE WLY OR AT LEAST BROAD...FLAT TROUGHING SHOULD COVER THE MIDWEST ON WEDNESDAY...ALLOWING FOR SOME MODERATION OF TEMPERATURES ON WEDNESDAY AND THURSDAY...WITH HIGHS IN THE UPPER 20S TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY. A REINFORCING SHOT OF COLD AIR ASSOCIATED WITH A STRONG NORTHERN STREAM SHORTWAVE DIGGING INTO THE UPPER MISSISSIPPI VALLEY AND SOUTHERN GREAT LAKES WILL BRING SUB-ZERO TEMPERATURES BACK TO MUCH OF THE CWA FOR FRIDAY MORNING. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * IFR/LIFR CIGS CONTINUING OVERNIGHT AND LIKELY THROUGH SATURDAY...THOUGH A BRIEF PERIOD OF MVFR IS POSSIBLE IN THE MORNING. * IFR VSBY AT MDW MAY IMPROVE SLIGHTLY LATER TONIGHT. * TIMING AND TYPE OF PRECIP ONSET LATER TODAY. MDB //DISCUSSION...UPDATED 06Z... ONE LOW PRESSURE AREA IS OFF TO THE EAST WHILE THE NEXT LOW DEVELOPS OVER SOUTHWEST ARKANSAS. DRIZZLE/FREEZING DRIZZLE HAS DIMINISHED IN COVERAGE DURING THE EVENING BUT VSBY HAS STRUGGLED TO IMPROVE IN MANY AREAS...THOUGH ORD HAS IMPROVED TO GREATER THAN 6SM. SEVERAL SITES HAVE LOST SOME VSBY IN THE LAST HOUR OR SO INCLUDING MDW SO WILL CARRY SOME LOWER VSBY THAN PREVIOUS TAFS TO ACCOUNT FOR THIS. TOUGH TO SAY WHETHER THERE WILL BE MUCH IMPROVEMENT OVERNIGHT DESPITE THE LACK OF DRIZZLE NOW OCCURRING SO FURTHER ADJUSTMENTS MAY BE NEEDED. OTHERWISE EXPECT IFR/LIFR CIGS TO PERSIST THROUGH THE MORNING. THE ARKANSAS LOW WILL MOVE NORTHEAST TODAY SPREADING PRECIPITATION NORTHWARD INTO THE AREA. -DZ/-FZDZ MAY DEVELOP AS UPWARD MOTION BEGINS TO INCREASE MID/LATE MORNING. OTHERWISE CHANCES FOR MIXED PRECIPITATION WILL INCREASE DURING THE AFTERNOON FROM SOUTH TO NORTH...WITH RAIN/SNOW/SLEET ALL POSSIBLE. WITH SURFACE TEMPS RIGHT AROUND FREEZING...SOME FREEZING RAIN MAY ALSO OCCUR. PRECIP INTENSITY MAXIMIZES BY EARLY EVENING WITH WARMER AIR MOVING IN ALOFT FAVORING MORE RAIN AT MDW/GYY WITH RAIN/SLEET POSSIBLE AT ORD/DPA AND A TRANSITION FROM SNOW/SLEET TO SNOW AT RFD WHERE TEMPS ALOFT WILL BE COLDER. DRIER AIR IS FORECAST TO MOVE IN ALOFT DURING THE LATE EVENING HOURS WHICH WOULD LIKELY RESULT IN A LULL IN PRECIP INTENSITY AND FAVOR -DZ/-FZDZ DEPENDING ON SURFACE TEMPERATURE. RFD MAY REMAIN ON THE FRINGE OF THE DRY SLOT ALLOWING FOR FLUCTUATIONS BETWEEN SNOW AND -FZDZ. WEST AND NORTHWEST WINDS WILL TURN NORTHEAST LATER THIS MORNING AND INCREASE IN SPEED INTO THE EVENING. MDB //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH CONFIDENCE IN IFR/LIFR CIGS CONTINUING OVERNIGHT. LOW CONFIDENCE IN ANY IMPROVEMENT TO MVFR CIGS. * LOW-MEDIUM CONFIDENCE IN SOME VSBY IMPROVEMENT AT MDW OVERNIGHT. * MEDIUM CONFIDENCE IN TIMING/PRECIP TYPE TRENDS LATER TODAY. MDB //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...SNOW ESPECIALLY IN THE MORNING. IFR LIKELY. BRIEF LIFR POSSIBLE EARLY. MONDAY...CHANCE OF SNOW SHOWERS. MVFR/IFR POSSIBLE. TUESDAY...VFR. WEDNESDAY...CHANCE OF LIGHT SNOW. MVFR/IFR POSSIBLE. THURSDAY...SLIGHT CHANCE OF LIGHT SNOW. MVFR POSSIBLE. RATZER && .MARINE... 218 PM...LOW PRESSURE OVER CENTRAL ILLINOIS WILL MOVE NORTHEAST ACROSS THE EASTERN LAKES TONIGHT AS IT SLOWLY WEAKENS AS WEAK HIGH PRESSURE OVER THE UPPER MIDWEST IS ABSORBED BY STRONGER HIGH PRESSURE MOVING ACROSS SOUTHERN CANADA SATURDAY AND SATURDAY NIGHT. THE GRADIENT WILL SLOWLY WEAKEN TONIGHT WITH SPEEDS IN THE 10-15 KT RANGE BY MORNING. NEW LOW PRESSURE WILL DEVELOP OVER TEXAS TONIGHT AND MOVE NORTHEAST TO NORTHERN INDIANA BY SUNDAY MORNING. AS THIS LOW APPROACHES THE LAKES REGION...IT WILL DEEPEN AND THE GRADIENT WILL TIGHTEN BETWEEN THE STRONGER HIGH ACROSS SOUTHERN CANADA. NORTHEAST WINDS WILL STEADILY INCREASE SATURDAY EVENING WITH 30 KTS EXPECTED. DEPENDING ON THE EXACT STRENGTH AND TRACK OF THIS LOW...ITS POSSIBLE THERE COULD BE A PERIOD OF LOW END GALES BUT CONFIDENCE IS TOO LOW TO INCLUDE IN THIS FORECAST. A TROUGH OF LOW PRESSURE WILL THEN LINGER ACROSS THE WESTERN LAKES REGION SUNDAY NIGHT WITH NORTHERLY WINDS SHIFTING NORTHWESTERLY. STRONG HIGH PRESSURE WILL BUILD ACROSS THE PLAINS SUNDAY AND SUNDAY NIGHT AND THEN SHIFT EAST ACROSS THE LAKES REGION MONDAY NIGHT AND TUESDAY. THERE IS A POTENTIAL FOR A PERIOD OF STRONG WINDS AHEAD OF THE HIGH...IN THE MONDAY/MONDAY NIGHT TIME PERIOD. BUT CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD REMAIN LOW. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010- ILZ011...6 PM SATURDAY TO 6 PM SUNDAY. WINTER STORM WATCH...ILZ006-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY. FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 6 AM SUNDAY. IN...FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 6 AM SUNDAY. 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
NWS INDIANAPOLIS IN
950 PM EST SUN DEC 22 2013 .UPDATE... THE NEAR TERM 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 230300Z KIND TAF UPDATE/... ISSUED AT 920 PM EST SUN DEC 22 2013 NO SIGNIFICANT CHANGES MADE TO THE FORECAST AT THIS TIME. PREVIOUS DISCUSSION FOLLOWS. WIDESPREAD MVFR CEILINGS AROUND 012 CURRENTLY ACROSS THE AREA EXPECTED TO CONTINUE AT THE TAF SITES TONIGHT AS MOISTURE REMAINS TRAPPED BELOW AN INVERSION. SOME BRIEF PERIODS OF IFR CEILINGS 008-009 AGL ALONG WITH SOME VISIBILITY RESTRICTIONS IN LIGHT DRIZZLE OR LIGHT SNOW POSSIBLE TONIGHT AS AN UPPER TROUGH MOVES THROUGH...BUT THESE CONDITIONS SHOULD NOT BE TOO WIDESPREAD OR PROLONGED IN NATURE. SURFACE WINDS GENERALLY AT OR BELOW 12 KTS THROUGH 231200Z. && .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 GOODLAND KS
635 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 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 423 PM MST SUN DEC 22 2013 VFR CONDITIONS WILL BEGIN THE TAF PERIOD...THEN DROP TO MVFR WITH THE COLD FRONT AND UPPER DISTURBANCE MOVING THROUGH BRINGING A CHANCE FOR SNOW. IFR CEILINGS ARE ALSO POSSIBLE...WITH IFR VISIBILITY OVER KMCK...ACCOMPANYING THE LIGHT SNOW TONIGHT. FOR KGLD...BUFKIT SOUNDINGS AND MODELS SHOW VFR DECREASING TO MVFR AROUND 05Z WITH LIGHT SNOW. THE BEST CHANCE FOR LIGHT SNOW APPEARS TO BE BETWEEN 06Z AND 10Z...SO INCLUDED A TEMPO GROUP FOR IFR CEILINGS SINCE THEY COULD FLUCTUATE DURING THE TIME PERIOD. VISIBILITY SHOULD REMAIN AROUND 6SM SINCE SNOW WILL BE VERY LIGHT...BUT INCLUDED 4SM IN TEMPO GROUP FOR FLUCTUATIONS OF SLIGHTLY HEAVIER SNOWFALL. SNOW SHOULD COME TO AN END AROUND 12Z WITH VFR CONDITIONS RESUMING AROUND 15Z. FOR KMCK...SOUNDINGS AND MODELS SHOW LIGHT SNOW MOVING INTO THE TERMINAL BETWEEN 02 AND 03Z...SO INCLUDED A TEMPO GROUP FOR WHEN THE SNOW STARTS OVER KMCK. CEILINGS WILL ALSO START TO LOWER TO MVFR AROUND THIS TIME. BETTER FORCING WILL OCCUR OVER KMCK...SO INCLUDED A TEMPO GROUP FOR CEILINGS LOWERING TO IFR AND VISIBILITY LOWERING TO IFR AT 2SM WITH THE HEAVIER SNOW THAT MOVES THROUGH. SNOW IS ALSO EXPECTED TO COME TO AN END AROUND 12Z...WITH CEILINGS REMAINING MVFR THROUGH 18Z. CONDITIONS WILL IMPROVE TO VFR AROUND 18Z. CONSIDERING SOUNDINGS WERE A LITTLE MISLEADING ON PREVIOUS DAYS AND GUIDANCE IS NO HELP WHAT-SO-EVER...AMENDMENTS WILL BE MADE AS CHANGES TAKE PLACE. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...99 SHORT TERM...FS LONG TERM...JJM AVIATION...ALW
AREA FORECAST DISCUSSION...UPDATED
NWS DODGE CITY KS
1112 AM CST Sat Dec 21 2013 ...Updated for Aviation... .SHORT TERM...(This evening through Saturday) ISSUED AT 355 AM CST SAT DEC 21 2013 A strong shortwave trough centered west of El Paso early this morning will eject northeastward across the southern plains through this evening. Plenty of low level moisture was being ejected into this system from the south. The deformation/trowal will set up across southwestern Kansas later today and the 06z NAM and 00 UTC ECMWF seem to have the best handle on the distribution and amounts of snow. Given that this is a fast moving system, snow totals of 2 to 5 inches are generally expected in the advisory area along and southeast of a line from Elkhart to Garden City to Ness City to LaCrosse, with the highest amounts from Meade eastward into Barber and Pratt counties. A few locations could reach 6 inches. The snow may start off as sleet or freezing rain in south central Kansas later this morning since RAP soundings show an elevated warm layer around 1C through 18Z. Temperatures may rise into the upper 20s and lower 30s before the snow arrives, and then fall back into the mid 20s. Afternoon temperatures will be warmer in places like Syracuse, Scott City and Dighton where not much in the way of snow is expected. Temperatures tonight will be held up by 10kt north winds and cloud cover; but with fairly chilly air pushing southward out of the northern plains in the wake of the storm system, temperatures should drop into the teens. .LONG TERM...(Sunday through Friday) ISSUED AT 246 AM CST SAT DEC 21 2013 Models this morning were in fairly good agreement with lifting a weakening upper level trough across the Mid Mississippi Valley on Sunday. At the same time a northern branch upper level trough will move out of the Rockies and across the Central Plains as an area of high pressure at the surface builds into western Kansas. Although no measurable precipitation is expected with this next system, there will be some increasing clouds late Sunday into Sunday night. This increasing cloud cover will limit how cold temperatures will fall Sunday night, however give light winds and fresh snow cover across western Kansas will still undercut the coolest guidance for overnight lows. Temperatures falling back into the single digits still looks reasonable. Lows near zero no out of the question near the Oklahoma border if skies remain clear for several hours after midnight. Westerly downslope flow will improve early next week which will allow temperatures to gradually warm. Snow cover will limit how much warming will occur Monday and Tuesday, but at this time the latest CRExtendFcst_Init still looks reasonable. Where the heavier snowfall is expected later today the afternoon temperatures are expected to warm into the upper 30s by Tuesday afternoon. Elsewhere highs in the mid to upper 40s still appear likely given the 850mb temperature trends from the GFS and ECMWF. This slow warming trend will briefly end mid week as a cold front drops south across Kansas Tuesday night Wednesday. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) ISSUED AT 1107 AM CST SAT DEC 21 2013 The track of the upper level storm and attendant heavy snow axis is forecast to be just east of the KDDC terminal. Some MVFR conditions are possible mainly at KDDC with light snow and north winds around 10kts after 19Z through around 05Z before the snow moves off to the east. && .PRELIMINARY POINT TEMPS/POPS... DDC 30 18 28 4 / 80 90 0 0 GCK 31 18 29 9 / 20 20 0 0 EHA 28 18 32 17 / 50 40 0 0 LBL 28 18 29 11 / 80 40 0 0 HYS 32 16 28 10 / 20 30 10 20 P28 29 19 27 3 / 100 100 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY until Midnight CST tonight FOR KSZ046- 063>066-075>081-084>090. && $$ SHORT TERM...Finch LONG TERM...Burgert AVIATION...Kruse
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
507 AM CST Sat Dec 21 2013 ...Updated aviation discussion... .SHORT TERM...(This evening through Saturday) ISSUED AT 355 AM CST SAT DEC 21 2013 A strong shortwave trough centered west of El Paso early this morning will eject northeastward across the southern plains through this evening. Plenty of low level moisture was being ejected into this system from the south. The deformation/trowal will set up across southwestern Kansas later today and the 06z NAM and 00 UTC ECMWF seem to have the best handle on the distribution and amounts of snow. Given that this is a fast moving system, snow totals of 2 to 5 inches are generally expected in the advisory area along and southeast of a line from Elkhart to Garden City to Ness City to LaCrosse, with the highest amounts from Meade eastward into Barber and Pratt counties. A few locations could reach 6 inches. The snow may start off as sleet or freezing rain in south central Kansas later this morning since RAP soundings show an elevated warm layer around 1C through 18Z. Temperatures may rise into the upper 20s and lower 30s before the snow arrives, and then fall back into the mid 20s. Afternoon temperatures will be warmer in places like Syracuse, Scott City and Dighton where not much in the way of snow is expected. Temperatures tonight will be held up by 10kt north winds and cloud cover; but with fairly chilly air pushing southward out of the northern plains in the wake of the storm system, temperatures should drop into the teens. .LONG TERM...(Sunday through Friday) ISSUED AT 246 AM CST SAT DEC 21 2013 Models this morning were in fairly good agreement with lifting a weakening upper level trough across the Mid Mississippi Valley on Sunday. At the same time a northern branch upper level trough will move out of the Rockies and across the Central Plains as an area of high pressure at the surface builds into western Kansas. Although no measurable precipitation is expected with this next system, there will be some increasing clouds late Sunday into Sunday night. This increasing cloud cover will limit how cold temperatures will fall Sunday night, however give light winds and fresh snow cover across western Kansas will still undercut the coolest guidance for overnight lows. Temperatures falling back into the single digits still looks reasonable. Lows near zero no out of the question near the Oklahoma border if skies remain clear for several hours after midnight. Westerly downslope flow will improve early next week which will allow temperatures to gradually warm. Snow cover will limit how much warming will occur Monday and Tuesday, but at this time the latest CRExtendFcst_Init still looks reasonable. Where the heavier snowfall is expected later today the afternoon temperatures are expected to warm into the upper 30s by Tuesday afternoon. Elsewhere highs in the mid to upper 40s still appear likely given the 850mb temperature trends from the GFS and ECMWF. This slow warming trend will briefly end mid week as a cold front drops south across Kansas Tuesday night Wednesday. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) ISSUED AT 505 AM CST SAT DEC 21 2013 Clouds will thicken and lower today with low VFR cigs expected to develop after 15z at DDC and GCK. MVFR cigs are then expected to develop by 21z. With the lowering cigs some light snow is also expected to develop with a period of steady light snow appearing most likely between 21z and 03z. At HYS cigs will also be lowering through the day, however based on the 06z NAM BUFR soundings VFR cigs are expected today and early tonight. North winds will continue at 10 knots or less at all three taf sites. && .PRELIMINARY POINT TEMPS/POPS... DDC 30 18 28 4 / 90 90 0 0 GCK 31 18 29 9 / 50 30 0 0 EHA 28 18 32 17 / 90 20 0 0 LBL 28 18 29 11 / 100 40 0 0 HYS 32 16 28 10 / 40 60 10 20 P28 29 19 27 3 / 100 90 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY until Midnight CST tonight FOR KSZ046- 063>066-075>081-084>090. && $$ SHORT TERM...Finch LONG TERM...Burgert AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
355 AM CST Sat Dec 21 2013 ...Updated for short term discussion... .SHORT TERM...(This evening through Saturday) ISSUED AT 355 AM CST SAT DEC 21 2013 A strong shortwave trough centered west of El Paso early this morning will eject northeastward across the southern plains through this evening. Plenty of low level moisture was being ejected into this system from the south. The deformation/trowal will set up across southwestern Kansas later today and the 06z NAM and 00 UTC ECMWF seem to have the best handle on the distribution and amounts of snow. Given that this is a fast moving system, snow totals of 2 to 5 inches are generally expected in the advisory area along and southeast of a line from Elkhart to Garden City to Ness City to LaCrosse, with the highest amounts from Meade eastward into Barber and Pratt counties. A few locations could reach 6 inches. The snow may start off as sleet or freezing rain in south central Kansas later this morning since RAP soundings show an elevated warm layer around 1C through 18Z. Temperatures may rise into the upper 20s and lower 30s before the snow arrives, and then fall back into the mid 20s. Afternoon temperatures will be warmer in places like Syracuse, Scott City and Dighton where not much in the way of snow is expected. Temperatures tonight will be held up by 10kt north winds and cloud cover; but with fairly chilly air pushing southward out of the northern plains in the wake of the storm system, temperatures should drop into the teens. .LONG TERM...(Sunday through Friday) ISSUED AT 246 AM CST SAT DEC 21 2013 Models this morning were in fairly good agreement with lifting a weakening upper level trough across the Mid Mississippi Valley on Sunday. At the same time a northern branch upper level trough will move out of the Rockies and across the Central Plains as an area of high pressure at the surface builds into western Kansas. Although no measurable precipitation is expected with this next system, there will be some increasing clouds late Sunday into Sunday night. This increasing cloud cover will limit how cold temperatures will fall Sunday night, however give light winds and fresh snow cover across western Kansas will still undercut the coolest guidance for overnight lows. Temperatures falling back into the single digits still looks reasonable. Lows near zero no out of the question near the Oklahoma border if skies remain clear for several hours after midnight. Westerly downslope flow will improve early next week which will allow temperatures to gradually warm. Snow cover will limit how much warming will occur Monday and Tuesday, but at this time the latest CRExtendFcst_Init still looks reasonable. Where the heavier snowfall is expected later today the afternoon temperatures are expected to warm into the upper 30s by Tuesday afternoon. Elsewhere highs in the mid to upper 40s still appear likely given the 850mb temperature trends from the GFS and ECMWF. This slow warming trend will briefly end mid week as a cold front drops south across Kansas Tuesday night Wednesday. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 1202 AM CST SAT DEC 21 2013 A strong upper level system will pass across Oklahoma on Saturday. CIGS will lower to IFR at KDDC as snow develops by 18-21z, with visibilities as low as 1 mile in the heaviest snow between 21-24z. KHYS and KGCK will be on the edge of the precipitation shield so that only minor restrictions to visibility to 1-3 miles are expected. The snow will be ending after 02z and ceilings and visibilities will dramatically improve. && .PRELIMINARY POINT TEMPS/POPS... DDC 30 17 28 4 / 90 90 0 0 GCK 31 18 29 9 / 50 30 0 0 EHA 28 20 32 17 / 90 20 0 0 LBL 28 18 29 11 / 100 40 0 0 HYS 32 16 28 10 / 40 60 10 20 P28 29 17 27 3 / 100 90 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY until Midnight CST tonight FOR KSZ045- 046-063>066-075>081-084>090. && $$ SHORT TERM...Finch LONG TERM...Burgert AVIATION...Finch
AREA FORECAST DISCUSSION
NWS JACKSON KY
306 AM EST SAT DEC 21 2013 .UPDATE... ISSUED AT 119 AM EST SAT DEC 21 2013 BASED ON RECENT TRENDS...UPDATED TO LOWER WINDS SLIGHTLY OVERNIGHT AND TO RAISE MIN TEMPS A BIT. UPDATE ISSUED AT 1100 PM EST FRI DEC 20 2013 CURRENT CONDITIONS ACROSS THE AREA AS OF 04Z FEATURE SOME SCATTERED SHOWERS MOVING NORTHEAST FROM TN INTO THE SOUTH CENTRAL AND SOUTHERN I-75 CORRIDOR OF KENTUCKY. GENERALLY...THE NAM AND HRRR ARE AGREEING ON ISOLATED TO SCATTERED SHOWERS SKIRTING THE WESTERN EXTEND OF THE CWA...OR I-75 CORRIDOR THROUGH THE REST OF THE NIGHT. THE BEST LIFT AND MOISTURE ARRIVES IN THE NORTHWEST IN THE 09Z TO 12Z TIME FRAME AND IF THERE EVER IS A CHANCE FOR THUNDER TONIGHT...IT WILL OCCUR DURING THIS PERIOD IN THE PREDAWN HOURS AND KEPT A SLIGHT CHANCE IN THE FORECAST DUE TO THE LACK OF LIFT AND MOISTURE AT THIS TIME. HAVE UPDATED AND SENT OUT A FRESH ZFP TO ACCOUNT FOR THIS ADJUSTMENT AND LOADED CURRENT OBSERVATIONS AND SENT GRIDS TO NDFD. UPDATE ISSUED AT 830 PM EST FRI DEC 20 2013 AS OF 0130Z SOME SHOWERS ARE BEGINNING TO DEVELOP AND MOVE INTO THE AREA FROM THE SOUTH AS THE MOISTURE SURGE AND LIFT DEVELOPS AND MOVES IN FROM THE SOUTHWEST. UPDATED THE GRIDS WITH THE MOST CURRENT OBS AND HAVE SENT THEM TO NDFD. THE REST OF THE FORECAST IS ON TRACK. UPDATE ISSUED AT 715 PM EST FRI DEC 20 2013 CURRENT CONDITIONS ACROSS THE AREA FEATURE A FEW STRAY SHOWERS PASSING THROUGH EASTERN KENTUCKY BUT OTHERWISE ANY MEASURABLE PRECIP LOOKS TO BE NONEXISTENT FOR AT LEAST THE NEXT COUPLE OF HOURS SO AT THIS POINT...SLIGHT CHANCE SHOWERS LOOK TO BE THE WAY TO GO AND THEN AS LIFT AND MOISTURE SURGE INCREASES TONIGHT...WILL INTRODUCE SOME CHANCE AND LIKELY SHOWERS WITH AT LEAST SOME NOTICEABLE ISENTROPIC LIFT JUST SKIRTING TO THE WEST OF THE I-75 CORRIDOR...WILL LEAVE SLIGHT CHANCE THUNDERSTORMS JUST IN THE WESTERN ZONES AND ONLY STARTING IN THE PREDAWN HOURS. HAVE ADJUSTED FOR PRECIP CHANCES ARRIVING LATER SO A FRESH ZFP HAS BEEN ISSUED FOR THESE SLIGHT CHANGES. OTHERWISE...HAVE LOADED IN THE LATEST OB AND SENT THE GRIDS TO NDFD. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 359 PM EST FRI DEC 20 2013 ISOLATED TO SCATTERED SHOWERS HAVE BEEN MOVING ACROSS EASTERN KENTUCKY TODAY. A FRONTAL SYSTEM EXTENDS FROM SOUTHERN MICHIGAN TO NORTH CENTRAL TEXAS AND HAS MULTIPLE WAVES MOVING ALONG IT. THIS WILL RESULT IN THE FRONT BOWING TO THE NORTH AHEAD OF THE LOW AND THEN BOWING DOWN ON THE BACK SIDE OF THE LOW. THIS WILL CAUSE THE FRONTS TO MOVE PRECIPITATION IN AND OUT OF THE AREA. THE COLD FRONT WILL FINALLY MOVE THROUGH THE AREA ON SUNDAY WHEN THE UPPER TROUGH MOVES TO THE WEST AND NORTH OF THE AREA. THE LATEST MODEL RUNS ARE MOVING THE FRONT THROUGH THE AREA ON SUNDAY MORNING. THERE WILL BE A STRONG LOW LEVEL JET OUT AHEAD OF THE FRONT. THE JET WILL BE MOVING INTO THE AREA ON SATURDAY NIGHT. PUT OUT A LAKE WIND ADVISORY TO COVER THE WIND GUSTS EXPECTED WITH THIS SYSTEM. IT IS POSSIBLE THAT THIS MAY HAVE TO BE UPGRADED TO A WIND ADVISORY...HOWEVER SINCE IT WILL BE NIGHT TIME...IT WILL BE HARDER TO MIX THE STRONGER GUSTS DOWN TO THE SURFACE. THE UPPER ELEVATIONS WOULD BE MOST LIKELY TO SEE THE STRONGEST GUSTS. THE SEVERE WEATHER THREAT IS ALSO MINIMIZED DUE TO THE TIME OF DAY THE FRONT WILL BE MOVING THROUGH THE AREA. THE AMOUNT OF PRECIPITATION EXPECTED WITH THIS SYSTEM IS LIMITED...BECAUSE THE FRONT WILL BE MOVING FAIRLY QUICKLY THROUGH THE AREA. THE BEST CHANCE TO SEE THE HEAVY RAIN WILL BE OUT AHEAD OF THE FRONT ON SATURDAY NIGHT. NEAR RECORD TEMPERATURES ARE EXPECTED TOMORROW. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 306 AM EST SAT DEC 21 2013 THE SURFACE COLD FRONT WHICH BROUGHT THE RAIN AND WINDS DURING THE SHORT TERM WILL HAVE MOVED SE OF THE REGION BY 0Z MONDAY. HOWEVER...MODELS STILL SHOW A POOL OF MOISTURE/LIGHT PRECIP REMAINING OVER THE FAR SE COUNTIES OF THE CWA. BASED ON LATEST SOUNDINGS...THERE DOES SEEM TO BE A THIN LAYER OF DRY AIR NEAR THE SURFACE WHICH COULD INHIBIT RAIN ACROSS THE REMAINDER OF THE REGION. AS A RESULT...WAS RELUCTANT TO PUT IN ANYTHING OTHER THAN SLIGHT CHANCE POPS FOR SEVERAL HOURS IN THESE LOCATIONS...BUT IF PRECIP DOES OCCUR...IT WILL BE VERY LIGHT WITH LITTLE TO NO ACCUMULATION EXPECTED. IN CONTRAST...SE KY COULD SEE SEVERAL HUNDREDTHS OF AN INCH. THIS IS STILL RATHER UNIMPACTFUL. AN ABUNDANT AMOUNT OF DRY AIR SEEMS TO BE PULLING IN ALOFT TOO...SO EXPECT ANY CLOUD COVER TO BE CONFINED TO THE LOW LEVELS /LOW LEVEL CU/ INTO THE AFTERNOON HOURS ACROSS THE REGION. THOUGH WINDS ALOFT WILL CONTINUE TO BE QUITE STRONG...WITH HIGH PRESSURE COMING INTO PLAY...AND SIGNIFICANT DRYING ALOFT...A DECENT NIGHT TIME INVERSION WILL FORM SUNDAY NIGHT...PREVENTING THESE HIGHER WINDS FROM REACHING THE SURFACE. BY MONDAY AFTERNOON...THE INVERSION WILL LIFT...AND WINDS WILL BE ABLE TO MIX DOWN...BUT STILL SHOULD ONLY BE AROUND 15KTS OR LESS. FOR MONDAY NIGHT...THE UPPER LEVEL TROUGH AXIS WILL PASS ACROSS EASTERN KY. ONCE KY FINDS ITSELF ON THE BACK EDGE OF THIS TROUGH...EXPECT AN ABUNDANT AMOUNT OF DRY AND COLD CANADIAN AIR TO RUSH INTO THE REGION. FORECAST SOUNDINGS WILL COOL AND DRY DRAMATICALLY. DAYTIME HIGHS TUESDAY WILL BE SIGNIFICANTLY LOWER..BARELY REACHING FREEZING IN MOST LOCATIONS. TUESDAY NIGHT WILL BE A SIMILAR STORY...WITH LOWS EXPECTED TO DROP DOWN INTO THE UPPER TEENS TO NEAR 20. MODELS ARE STILL SEEING A HIGH AMOUNT OF DISAGREEMENT IN THE LONG TERM...BUT DO EXPECT SURFACE HIGH PRESSURE AND UPPER LEVEL RIDGING TO LAST THROUGH WEDNESDAY NIGHT. THEN THERE IS A POTENTIAL FOR ANOTHER SHORTWAVE TO MOVE INTO/NEAR THE OHIO VALLEY REGION DURING THE DAY THURSDAY. WITH SUCH AN ABUNDANT AMOUNT OF DRY AIR IN PLACE...DO NOT EXPECT ANY IMPACTS ON THURSDAY OTHER THAN HIGH CLOUDS. HOWEVER...WINDS WILL HAVE SWITCHED TO A MORE SRLY DIRECTION...ALLOWING FOR SOMEWHAT WARMER TEMPERATURES. A SHALLOW LAYER OF MOISTURE SHOULD MAKE IT DOWN TO THE SURFACE BY FRIDAY AFTERNOON/EVENING. BUT WILL AGREE WITH PREVIOUS FORECAST...THE MOISTURE IS SO SHALLOW...WOULD NOT EXPECT MUCH MORE THAN A LIGHT RAIN/DRIZZLE OR LIGHT SNOW EVENT. LITTLE TO NO ACCUMULATIONS ARE EXPECTED AT THIS TIME. WITH CLOUD COVER IN PLACE...TEMPERATURES SHOULD MODULATE AFTER THURSDAY...WITH HIGHS AND LOWS EXPECTED TO BE CLOSER TO NORMAL FOR THIS TIME OF YEAR. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 106 AM EST SAT DEC 21 2013 CONDITIONS AT TAF ISSUANCE WERE A MIX OF MVFR AND LOW END VFR DUE TO CEILINGS. THE MVFR WAS MOST PREVALENT IN THE WEST AND THE VFR MOST PREVALENT IN THE EAST. THIS GENERAL SCENARIO IS EXPECTED TO PERSIST OVERNIGHT...FOLLOWED BY PERHAPS A BIT OF IMPROVEMENT ON SATURDAY MORNING. WITH MORE HUMID LOW LEVEL AIR BEING ADVECTED INTO THE REGION FROM THE SW AND SOME LIMITED HEATING...WILL LOOK FOR A BKN LAYER OF MVFR LEVEL STRATOCUMULUS TO DEVELOP OVER MUCH OF THE AREA ON SATURDAY AFTERNOON...AND THEN DISSIPATE SATURDAY EVENING. SOME SHOWERS WILL ALSO BE POSSIBLE ON SATURDAY...WITH THE GREATEST PROBABILITY IN THE NW AROUND KIOB...AND THE LOWEST PROBABILITY IN THE SE NEAR THE VA BORDER. && .JKL WATCHES/WARNINGS/ADVISORIES... LAKE WIND ADVISORY FROM 7 PM THIS EVENING TO 1 PM EST SUNDAY FOR KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120. && $$ UPDATE...HAL SHORT TERM...JJ LONG TERM...JMW AVIATION...HAL
AREA FORECAST DISCUSSION
NWS JACKSON KY
119 AM EST SAT DEC 21 2013 .UPDATE... ISSUED AT 119 AM EST SAT DEC 21 2013 BASED ON RECENT TRENDS...UPDATED TO LOWER WINDS SLIGHTLY OVERNIGHT AND TO RAISE MIN TEMPS A BIT. UPDATE ISSUED AT 1100 PM EST FRI DEC 20 2013 CURRENT CONDITIONS ACROSS THE AREA AS OF 04Z FEATURE SOME SCATTERED SHOWERS MOVING NORTHEAST FROM TN INTO THE SOUTH CENTRAL AND SOUTHERN I-75 CORRIDOR OF KENTUCKY. GENERALLY...THE NAM AND HRRR ARE AGREEING ON ISOLATED TO SCATTERED SHOWERS SKIRTING THE WESTERN EXTEND OF THE CWA...OR I-75 CORRIDOR THROUGH THE REST OF THE NIGHT. THE BEST LIFT AND MOISTURE ARRIVES IN THE NORTHWEST IN THE 09Z TO 12Z TIME FRAME AND IF THERE EVER IS A CHANCE FOR THUNDER TONIGHT...IT WILL OCCUR DURING THIS PERIOD IN THE PREDAWN HOURS AND KEPT A SLIGHT CHANCE IN THE FORECAST DUE TO THE LACK OF LIFT AND MOISTURE AT THIS TIME. HAVE UPDATED AND SENT OUT A FRESH ZFP TO ACCOUNT FOR THIS ADJUSTMENT AND LOADED CURRENT OBSERVATIONS AND SENT GRIDS TO NDFD. UPDATE ISSUED AT 830 PM EST FRI DEC 20 2013 AS OF 0130Z SOME SHOWERS ARE BEGINNING TO DEVELOP AND MOVE INTO THE AREA FROM THE SOUTH AS THE MOISTURE SURGE AND LIFT DEVELOPS AND MOVES IN FROM THE SOUTHWEST. UPDATED THE GRIDS WITH THE MOST CURRENT OBS AND HAVE SENT THEM TO NDFD. THE REST OF THE FORECAST IS ON TRACK. UPDATE ISSUED AT 715 PM EST FRI DEC 20 2013 CURRENT CONDITIONS ACROSS THE AREA FEATURE A FEW STRAY SHOWERS PASSING THROUGH EASTERN KENTUCKY BUT OTHERWISE ANY MEASURABLE PRECIP LOOKS TO BE NONEXISTENT FOR AT LEAST THE NEXT COUPLE OF HOURS SO AT THIS POINT...SLIGHT CHANCE SHOWERS LOOK TO BE THE WAY TO GO AND THEN AS LIFT AND MOISTURE SURGE INCREASES TONIGHT...WILL INTRODUCE SOME CHANCE AND LIKELY SHOWERS WITH AT LEAST SOME NOTICEABLE ISENTROPIC LIFT JUST SKIRTING TO THE WEST OF THE I-75 CORRIDOR...WILL LEAVE SLIGHT CHANCE THUNDERSTORMS JUST IN THE WESTERN ZONES AND ONLY STARTING IN THE PREDAWN HOURS. HAVE ADJUSTED FOR PRECIP CHANCES ARRIVING LATER SO A FRESH ZFP HAS BEEN ISSUED FOR THESE SLIGHT CHANGES. OTHERWISE...HAVE LOADED IN THE LATEST OB AND SENT THE GRIDS TO NDFD. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 359 PM EST FRI DEC 20 2013 ISOLATED TO SCATTERED SHOWERS HAVE BEEN MOVING ACROSS EASTERN KENTUCKY TODAY. A FRONTAL SYSTEM EXTENDS FROM SOUTHERN MICHIGAN TO NORTH CENTRAL TEXAS AND HAS MULTIPLE WAVES MOVING ALONG IT. THIS WILL RESULT IN THE FRONT BOWING TO THE NORTH AHEAD OF THE LOW AND THEN BOWING DOWN ON THE BACK SIDE OF THE LOW. THIS WILL CAUSE THE FRONTS TO MOVE PRECIPITATION IN AND OUT OF THE AREA. THE COLD FRONT WILL FINALLY MOVE THROUGH THE AREA ON SUNDAY WHEN THE UPPER TROUGH MOVES TO THE WEST AND NORTH OF THE AREA. THE LATEST MODEL RUNS ARE MOVING THE FRONT THROUGH THE AREA ON SUNDAY MORNING. THERE WILL BE A STRONG LOW LEVEL JET OUT AHEAD OF THE FRONT. THE JET WILL BE MOVING INTO THE AREA ON SATURDAY NIGHT. PUT OUT A LAKE WIND ADVISORY TO COVER THE WIND GUSTS EXPECTED WITH THIS SYSTEM. IT IS POSSIBLE THAT THIS MAY HAVE TO BE UPGRADED TO A WIND ADVISORY...HOWEVER SINCE IT WILL BE NIGHT TIME...IT WILL BE HARDER TO MIX THE STRONGER GUSTS DOWN TO THE SURFACE. THE UPPER ELEVATIONS WOULD BE MOST LIKELY TO SEE THE STRONGEST GUSTS. THE SEVERE WEATHER THREAT IS ALSO MINIMIZED DUE TO THE TIME OF DAY THE FRONT WILL BE MOVING THROUGH THE AREA. THE AMOUNT OF PRECIPITATION EXPECTED WITH THIS SYSTEM IS LIMITED...BECAUSE THE FRONT WILL BE MOVING FAIRLY QUICKLY THROUGH THE AREA. THE BEST CHANCE TO SEE THE HEAVY RAIN WILL BE OUT AHEAD OF THE FRONT ON SATURDAY NIGHT. NEAR RECORD TEMPERATURES ARE EXPECTED TOMORROW. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 409 PM EST FRI DEC 20 2013 THE EXTENDED WILL START OUT WITH A DEEP TROUGH ACROSS THE CENTRAL CONUS. THIS TROUGH WILL DAMPEN AS IT BECOMES MORE CONSOLIDATED OVER NEW ENGLAND BY TUESDAY. A SURFACE COLD FRONT WILL CONTINUE ITS SAG TO THE SOUTHEAST SUNDAY NIGHT...WITH DEEPER MOISTURE EXITING EASTERN KENTUCKY BY MONDAY MORNING. COLDER AIR WILL BE MOVING IN...WITH TEMPERATURES LIKELY FALLING THROUGH THE DAY ON MONDAY. THERE CONTINUES TO BE ENOUGH MOISTURE ADVERTISED FROM MONDAY THROUGH MONDAY NIGHT TO JUSTIFY SOME SLIGHT CHANCE POPS...LIKELY IN THE FORM OF FINE RAIN/DRIZZLE OR A BIT OF LIGHT SNOW OR FLURRIES. DRY AND COLDER WEATHER WILL BE IN PLACE HEADING INTO MID-WEEK...WITH LOWS DOWN INTO THE TEENS AND 20S TUESDAY AND WEDNESDAY MORNINGS. ANOTHER TROUGH WILL TAKE AIM AT THE REGION BY THURSDAY...HOWEVER THE MODEL DISAGREEMENT REMAINS. IN GENERAL...THERE HAS BEEN A DRIER TREND...SO UNDERCUT THE GIVEN BLENDED MODEL GUIDANCE OUTPUT A BIT AND KEPT SLIGHT CHANCE POPS IN. TEMPERATURE PROFILES SUPPORT RAIN/SNOW...HOWEVER LITTLE IF ANY SNOW ACCUMULATION LOOKS TO OCCUR. ANOTHER REINFORCING SHOT OF DRY AND COLDER HIGH PRESSURE WILL FOLLOW FOR FRIDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 106 AM EST SAT DEC 21 2013 CONDITIONS AT TAF ISSUANCE WERE A MIX OF MVFR AND LOW END VFR DUE TO CEILINGS. THE MVFR WAS MOST PREVALENT IN THE WEST AND THE VFR MOST PREVALENT IN THE EAST. THIS GENERAL SCENARIO IS EXPECTED TO PERSIST OVERNIGHT...FOLLOWED BY PERHAPS A BIT OF IMPROVEMENT ON SATURDAY MORNING. WITH MORE HUMID LOW LEVEL AIR BEING ADVECTED INTO THE REGION FROM THE SW AND SOME LIMITED HEATING...WILL LOOK FOR A BKN LAYER OF MVFR LEVEL STRATOCUMULUS TO DEVELOP OVER MUCH OF THE AREA ON SATURDAY AFTERNOON...AND THEN DISSIPATE SATURDAY EVENING. SOME SHOWERS WILL ALSO BE POSSIBLE ON SATURDAY...WITH THE GREATEST PROBABILITY IN THE NW AROUND KIOB...AND THE LOWEST PROBABILITY IN THE SE NEAR THE VA BORDER. && .JKL WATCHES/WARNINGS/ADVISORIES... LAKE WIND ADVISORY FROM 7 PM THIS EVENING TO 1 PM EST SUNDAY FOR KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120. && $$ UPDATE...HAL SHORT TERM...JJ LONG TERM...GEOGERIAN AVIATION...HAL
AREA FORECAST DISCUSSION
NWS JACKSON KY
106 AM EST SAT DEC 21 2013 .UPDATE... ISSUED AT 1100 PM EST FRI DEC 20 2013 CURRENT CONDITIONS ACROSS THE AREA AS OF 04Z FEATURE SOME SCATTERED SHOWERS MOVING NORTHEAST FROM TN INTO THE SOUTH CENTRAL AND SOUTHERN I-75 CORRIDOR OF KENTUCKY. GENERALLY...THE NAM AND HRRR ARE AGREEING ON ISOLATED TO SCATTERED SHOWERS SKIRTING THE WESTERN EXTEND OF THE CWA...OR I-75 CORRIDOR THROUGH THE REST OF THE NIGHT. THE BEST LIFT AND MOISTURE ARRIVES IN THE NORTHWEST IN THE 09Z TO 12Z TIME FRAME AND IF THERE EVER IS A CHANCE FOR THUNDER TONIGHT...IT WILL OCCUR DURING THIS PERIOD IN THE PREDAWN HOURS AND KEPT A SLIGHT CHANCE IN THE FORECAST DUE TO THE LACK OF LIFT AND MOISTURE AT THIS TIME. HAVE UPDATED AND SENT OUT A FRESH ZFP TO ACCOUNT FOR THIS ADJUSTMENT AND LOADED CURRENT OBSERVATIONS AND SENT GRIDS TO NDFD. UPDATE ISSUED AT 830 PM EST FRI DEC 20 2013 AS OF 0130Z SOME SHOWERS ARE BEGINNING TO DEVELOP AND MOVE INTO THE AREA FROM THE SOUTH AS THE MOISTURE SURGE AND LIFT DEVELOPS AND MOVES IN FROM THE SOUTHWEST. UPDATED THE GRIDS WITH THE MOST CURRENT OBS AND HAVE SENT THEM TO NDFD. THE REST OF THE FORECAST IS ON TRACK. UPDATE ISSUED AT 715 PM EST FRI DEC 20 2013 CURRENT CONDITIONS ACROSS THE AREA FEATURE A FEW STRAY SHOWERS PASSING THROUGH EASTERN KENTUCKY BUT OTHERWISE ANY MEASURABLE PRECIP LOOKS TO BE NONEXISTENT FOR AT LEAST THE NEXT COUPLE OF HOURS SO AT THIS POINT...SLIGHT CHANCE SHOWERS LOOK TO BE THE WAY TO GO AND THEN AS LIFT AND MOISTURE SURGE INCREASES TONIGHT...WILL INTRODUCE SOME CHANCE AND LIKELY SHOWERS WITH AT LEAST SOME NOTICEABLE ISENTROPIC LIFT JUST SKIRTING TO THE WEST OF THE I-75 CORRIDOR...WILL LEAVE SLIGHT CHANCE THUNDERSTORMS JUST IN THE WESTERN ZONES AND ONLY STARTING IN THE PREDAWN HOURS. HAVE ADJUSTED FOR PRECIP CHANCES ARRIVING LATER SO A FRESH ZFP HAS BEEN ISSUED FOR THESE SLIGHT CHANGES. OTHERWISE...HAVE LOADED IN THE LATEST OB AND SENT THE GRIDS TO NDFD. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 359 PM EST FRI DEC 20 2013 ISOLATED TO SCATTERED SHOWERS HAVE BEEN MOVING ACROSS EASTERN KENTUCKY TODAY. A FRONTAL SYSTEM EXTENDS FROM SOUTHERN MICHIGAN TO NORTH CENTRAL TEXAS AND HAS MULTIPLE WAVES MOVING ALONG IT. THIS WILL RESULT IN THE FRONT BOWING TO THE NORTH AHEAD OF THE LOW AND THEN BOWING DOWN ON THE BACK SIDE OF THE LOW. THIS WILL CAUSE THE FRONTS TO MOVE PRECIPITATION IN AND OUT OF THE AREA. THE COLD FRONT WILL FINALLY MOVE THROUGH THE AREA ON SUNDAY WHEN THE UPPER TROUGH MOVES TO THE WEST AND NORTH OF THE AREA. THE LATEST MODEL RUNS ARE MOVING THE FRONT THROUGH THE AREA ON SUNDAY MORNING. THERE WILL BE A STRONG LOW LEVEL JET OUT AHEAD OF THE FRONT. THE JET WILL BE MOVING INTO THE AREA ON SATURDAY NIGHT. PUT OUT A LAKE WIND ADVISORY TO COVER THE WIND GUSTS EXPECTED WITH THIS SYSTEM. IT IS POSSIBLE THAT THIS MAY HAVE TO BE UPGRADED TO A WIND ADVISORY...HOWEVER SINCE IT WILL BE NIGHT TIME...IT WILL BE HARDER TO MIX THE STRONGER GUSTS DOWN TO THE SURFACE. THE UPPER ELEVATIONS WOULD BE MOST LIKELY TO SEE THE STRONGEST GUSTS. THE SEVERE WEATHER THREAT IS ALSO MINIMIZED DUE TO THE TIME OF DAY THE FRONT WILL BE MOVING THROUGH THE AREA. THE AMOUNT OF PRECIPITATION EXPECTED WITH THIS SYSTEM IS LIMITED...BECAUSE THE FRONT WILL BE MOVING FAIRLY QUICKLY THROUGH THE AREA. THE BEST CHANCE TO SEE THE HEAVY RAIN WILL BE OUT AHEAD OF THE FRONT ON SATURDAY NIGHT. NEAR RECORD TEMPERATURES ARE EXPECTED TOMORROW. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 409 PM EST FRI DEC 20 2013 THE EXTENDED WILL START OUT WITH A DEEP TROUGH ACROSS THE CENTRAL CONUS. THIS TROUGH WILL DAMPEN AS IT BECOMES MORE CONSOLIDATED OVER NEW ENGLAND BY TUESDAY. A SURFACE COLD FRONT WILL CONTINUE ITS SAG TO THE SOUTHEAST SUNDAY NIGHT...WITH DEEPER MOISTURE EXITING EASTERN KENTUCKY BY MONDAY MORNING. COLDER AIR WILL BE MOVING IN...WITH TEMPERATURES LIKELY FALLING THROUGH THE DAY ON MONDAY. THERE CONTINUES TO BE ENOUGH MOISTURE ADVERTISED FROM MONDAY THROUGH MONDAY NIGHT TO JUSTIFY SOME SLIGHT CHANCE POPS...LIKELY IN THE FORM OF FINE RAIN/DRIZZLE OR A BIT OF LIGHT SNOW OR FLURRIES. DRY AND COLDER WEATHER WILL BE IN PLACE HEADING INTO MID-WEEK...WITH LOWS DOWN INTO THE TEENS AND 20S TUESDAY AND WEDNESDAY MORNINGS. ANOTHER TROUGH WILL TAKE AIM AT THE REGION BY THURSDAY...HOWEVER THE MODEL DISAGREEMENT REMAINS. IN GENERAL...THERE HAS BEEN A DRIER TREND...SO UNDERCUT THE GIVEN BLENDED MODEL GUIDANCE OUTPUT A BIT AND KEPT SLIGHT CHANCE POPS IN. TEMPERATURE PROFILES SUPPORT RAIN/SNOW...HOWEVER LITTLE IF ANY SNOW ACCUMULATION LOOKS TO OCCUR. ANOTHER REINFORCING SHOT OF DRY AND COLDER HIGH PRESSURE WILL FOLLOW FOR FRIDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 106 AM EST SAT DEC 21 2013 CONDITIONS AT TAF ISSUANCE WERE A MIX OF MVFR AND LOW END VFR DUE TO CEILINGS. THE MVFR WAS MOST PREVALENT IN THE WEST AND THE VFR MOST PREVALENT IN THE EAST. THIS GENERAL SCENARIO IS EXPECTED TO PERSIST OVERNIGHT...FOLLOWED BY PERHAPS A BIT OF IMPROVEMENT ON SATURDAY MORNING. WITH MORE HUMID LOW LEVEL AIR BEING ADVECTED INTO THE REGION FROM THE SW AND SOME LIMITED HEATING...WILL LOOK FOR A BKN LAYER OF MVFR LEVEL STRATOCUMULUS TO DEVELOP OVER MUCH OF THE AREA ON SATURDAY AFTERNOON...AND THEN DISSIPATE SATURDAY EVENING. SOME SHOWERS WILL ALSO BE POSSIBLE ON SATURDAY...WITH THE GREATEST PROBABILITY IN THE NW AROUND KIOB...AND THE LOWEST PROBABILITY IN THE SE NEAR THE VA BORDER. && .JKL WATCHES/WARNINGS/ADVISORIES... LAKE WIND ADVISORY FROM 7 PM THIS EVENING TO 1 PM EST SUNDAY FOR KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120. && $$ UPDATE...SHALLENBERGER SHORT TERM...JJ LONG TERM...GEOGERIAN AVIATION...HAL
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1158 PM CST Fri Dec 20 2013 .UPDATE... ISSUED AT 1158 PM CST FRI DEC 20 2013 The AVIATION section has been updated for the 06Z TAF issuance. UPDATE ISSUED AT 1016 PM CST FRI DEC 20 2013 Latest forecast update accounts for colder temperatures following cold front progressing southeast across the area. As of 04Z, the front stretched from roughly the Wabash River Valley to just east of Harrisburg, Illinois to just northwest of Cape Girardeau and Poplar Bluff, Missouri. Area Doppler radar mosaic depicts an initial round of showers and a few thunderstorms over mainly southern Illinois. The next round of activity was already lifting north across northeast Arkansas and western Tennessee and will spread across the region overnight. Utilized a blend of the NAM12, RAP13, and current forecast. Overall, going forecast appears to remain on track through Saturday morning. However, two potential scenarios could shift the forecast in one direction or another. (1.) The latter part of the RAP13 is much more aggressive with the southeastward progress of the cold frontal boundary into western Kentucky by Saturday afternoon. This can easily be supported by precipitation loading and its cooling effect, which may effectively push the frontal boundary further south than currently forecast. If this were to pan out, the potential for severe weather would essentially focus across the southern Pennyrile region and further south. (2.) Meanwhile, the NAM12 is much more insistent that the frontal boundary will hang up across far southeast Missouri, southeast Illinois, and even far southern Indiana. If this pans out, then the severe potential would be much more concerning by Saturday afternoon and evening. While the current forecast embraces neither of these extremes, they are nonetheless worth keeping in mind as we proceed through what promises to be a heavy rain event at the very least. && .SHORT TERM...(This Evening through Sunday) ISSUED AT 238 PM CST FRI DEC 20 2013 Flood Watch will continue as is tonight through Saturday night. Still looking at 2-4+ inches area wide, slightly higher amounts to 5 inches possible near and just NW of the Ohio River. Front will enter the area tonight and stall near the Ohio River. Rain and storms forecast to increase tonight especially after midnight, continuing through Saturday. Could see a few strong to severe storms Saturday late day and evening as wind fields increase substantially with some surface based instability along and south of the boundary, especially across west Kentucky. Isolated damaging wind gusts and a brief short lived tornado or two cannot be ruled out. The activity should quickly push to the east after midnight Saturday as we dry slot. Mid level drying will be pronounced, but low level moisture will linger with SW flow aloft. May be some drizzle into Sunday but that`s about it, as temperatures fall through the day. In terms of temps, dew points and winds with the front coming into the area tonight and Saturday, used a blend of RAP 13km data and short term 3 hourly GFS/NAM data. .LONG TERM...(Sunday Night through Friday) ISSUED AT 238 PM CST FRI DEC 20 2013 In the wake of the weekend storm...colder and drier air will arrive for early next week. Model soundings depict some lingering moisture Sunday night until the passage of the 850 mb trough axis. This could translate into some flurries or drizzle...but no measurable precip is indicated in the 12z gfs/nam/ecmwf model qpf. By Monday night...mainly clear skies are expected. Monday night...the combination of clear skies and decreasing winds should allow temps to radiate nicely. Will lower Monday night lows closer to gfs and ecmwf mos...both of which range from 10 to 15 degrees across most of the area. Tuesday will be another cold day...but there is about a 10 degree difference between ecmwf and gfs mos highs. The 00z ecmwf is more progressive with the eastward motion of the thermal trough...while the 12z gfs lingers the cold air through the day. Will split the difference between them...which yields highs in the upper 20s to lower 30s despite sunny skies. The models depict a 500 mb longwave trough axis setting up over the Mississippi Valley Christmas Day into Thursday. Shortwaves rotating through the trough will bring at least some cloudiness...if not measurable light precip. Model soundings have trended drier during this time period...and the 12z gfs and gfs ensemble mean show zero qpf. The 12z ecmwf indicates some patchy light precip. Will follow the model trends and lower pops into the slight chance category for Christmas night and Thursday. Precip type would be mainly snow until boundary layer temps become marginal for snow Thursday afternoon. In the wake of the departing longwave trough...another shot of cold air is expected for Friday. As would be expected seven days out...there is fair to poor agreement on how cold it will get. Forecast will represent a blend of gfs/ecmwf temps. && .AVIATION... ISSUED AT 1158 PM CST FRI DEC 20 2013 Low confidence forecast, with considerable uncertainty in the frontal position/movement through the period. It does appear that IFR conditions in heavy rain will prevail at all sites for most, if not all of the TAF period. Lower conditions will be possible at times, especially near the front, which unfortunately will be draped across the terminals for much of the period. The potential exists for some very strong and gusty south/southwest winds in the warm sector Saturday afternoon and evening. This would be most likely at KOWB, but cannot be ruled out at KPAH and KEVV. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH through late Saturday night FOR ILZ075>078-080>094. MO...FLOOD WATCH through late Saturday night FOR MOZ076-086-087-100- 107>112-114. IN...FLOOD WATCH through late Saturday night FOR INZ081-082-085>088. KY...FLOOD WATCH through late Saturday night FOR KYZ001>022. && $$ UPDATE...DRS AVIATION...DRS
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1016 PM CST Fri Dec 20 2013 .UPDATE... ISSUED AT 1016 PM CST FRI DEC 20 2013 Latest forecast update accounts for colder temperatures following cold front progressing southeast across the area. As of 04Z, the front stretched from roughly the Wabash River Valley to just east of Harrisburg, Illinois to just northwest of Cape Girardeau and Poplar Bluff, Missouri. Area Doppler radar mosaic depicts an initial round of showers and a few thunderstorms over mainly southern Illinois. The next round of activity was already lifting north across northeast Arkansas and western Tennessee and will spread across the region overnight. Utilized a blend of the NAM12, RAP13, and current forecast. Overall, going forecast appears to remain on track through Saturday morning. However, two potential scenarios could shift the forecast in one direction or another. (1.) The latter part of the RAP13 is much more aggressive with the southeastward progress of the cold frontal boundary into western Kentucky by Saturday afternoon. This can easily be supported by precipitation loading and its cooling effect, which may effectively push the frontal boundary further south than currently forecast. If this were to pan out, the potential for severe weather would essentially focus across the southern Pennyrile region and further south. (2.) Meanwhile, the NAM12 is much more insistent that the frontal boundary will hang up across far southeast Missouri, southeast Illinois, and even far southern Indiana. If this pans out, then the severe potential would be much more concerning by Saturday afternoon and evening. While the current forecast embraces neither of these extremes, they are nonetheless worth keeping in mind as we proceed through what promises to be a heavy rain event at the very least. && .SHORT TERM...(This Evening through Sunday) ISSUED AT 238 PM CST FRI DEC 20 2013 Flood Watch will continue as is tonight through Saturday night. Still looking at 2-4+ inches area wide, slightly higher amounts to 5 inches possible near and just NW of the Ohio River. Front will enter the area tonight and stall near the Ohio River. Rain and storms forecast to increase tonight especially after midnight, continuing through Saturday. Could see a few strong to severe storms Saturday late day and evening as wind fields increase substantially with some surface based instability along and south of the boundary, especially across west Kentucky. Isolated damaging wind gusts and a brief short lived tornado or two cannot be ruled out. The activity should quickly push to the east after midnight Saturday as we dry slot. Mid level drying will be pronounced, but low level moisture will linger with SW flow aloft. May be some drizzle into Sunday but that`s about it, as temperatures fall through the day. In terms of temps, dew points and winds with the front coming into the area tonight and Saturday, used a blend of RAP 13km data and short term 3 hourly GFS/NAM data. .LONG TERM...(Sunday Night through Friday) ISSUED AT 238 PM CST FRI DEC 20 2013 In the wake of the weekend storm...colder and drier air will arrive for early next week. Model soundings depict some lingering moisture Sunday night until the passage of the 850 mb trough axis. This could translate into some flurries or drizzle...but no measurable precip is indicated in the 12z gfs/nam/ecmwf model qpf. By Monday night...mainly clear skies are expected. Monday night...the combination of clear skies and decreasing winds should allow temps to radiate nicely. Will lower Monday night lows closer to gfs and ecmwf mos...both of which range from 10 to 15 degrees across most of the area. Tuesday will be another cold day...but there is about a 10 degree difference between ecmwf and gfs mos highs. The 00z ecmwf is more progressive with the eastward motion of the thermal trough...while the 12z gfs lingers the cold air through the day. Will split the difference between them...which yields highs in the upper 20s to lower 30s despite sunny skies. The models depict a 500 mb longwave trough axis setting up over the Mississippi Valley Christmas Day into Thursday. Shortwaves rotating through the trough will bring at least some cloudiness...if not measurable light precip. Model soundings have trended drier during this time period...and the 12z gfs and gfs ensemble mean show zero qpf. The 12z ecmwf indicates some patchy light precip. Will follow the model trends and lower pops into the slight chance category for Christmas night and Thursday. Precip type would be mainly snow until boundary layer temps become marginal for snow Thursday afternoon. In the wake of the departing longwave trough...another shot of cold air is expected for Friday. As would be expected seven days out...there is fair to poor agreement on how cold it will get. Forecast will represent a blend of gfs/ecmwf temps. && .AVIATION... ISSUED AT 559 PM CST FRI DEC 20 2013 Made a few modifications to the existing TAFs. MVFR ceilings are bouncing in and out across the area early this evening, so threw in a TEMPO to handle that situation. The front is just now entering the area and will pass KCGI this evening. It will settle over KPAH and KEVV late tonight and become stationary well into Saturday morning. Current thinking is that it will stay southeast of KCGI and not pass KOWB through the end of this TAF period. Added a couple of groups to handle the cha cha cha expected at KPAH and KEVV late tonight through late Saturday morning. Could see some strong south winds with gusts over 20kts Saturday afternoon, except at KCGI. Continued with the showers and VCTS through the day Saturday, with gradually lowering ceilings through the period. IFR or lower conditions are expected for much of the day. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH through late Saturday night FOR ILZ075>078-080>094. MO...FLOOD WATCH through late Saturday night FOR MOZ076-086-087-100- 107>112-114. IN...FLOOD WATCH through late Saturday night FOR INZ081-082-085>088. KY...FLOOD WATCH through late Saturday night FOR KYZ001>022. && $$ UPDATE...RJP AVIATION...DRS
AREA FORECAST DISCUSSION
NWS CARIBOU ME
953 PM EST SUN DEC 22 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 MONDAY/... 952 PM UPDATE...THERE CONTINUES TO BE A BREAK IN THE ACTION ACROSS DOWNEAST AREAS LATE THIS EVENING WITH FREEZING DRIZZLE FALLING IN SPOTS...BUT NOT THE HEAVIER FREEZING RAIN THAT IMPACTED THE AREA DURING THE DAY SUNDAY. THERE IS NOT MUCH CHANGE ACROSS NORTHERN MAINE EITHER FROM EARLIER THIS EVENING. THERE CONTINUES TO BE A BIT MORE COVERAGE AND INTENSITY TO THE PRECIPITATION FROM ABOUT LINCOLN NORTH. THE PRECIPITATION IS FALLING IN MOST AREAS AS SNOW...WITH A MIX OF SNOW AND SLEET ACROSS CENTRAL MAINE. 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 /MONDAY NIGHT 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 /02Z 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 MONDAY FOR MEZ011- 015>017-029-030-032. WINTER WEATHER ADVISORY UNTIL 4 PM EST MONDAY FOR MEZ003>006- 010-031. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EST MONDAY FOR ANZ050>052. && $$ NEAR TERM...CB/FOISY SHORT TERM...OKULSKI LONG TERM...OKULSKI AVIATION...CB/FOISY/OKULSKI MARINE...CB/FOISY/OKULSKI EQUIPMENT...CB
AREA FORECAST DISCUSSION
NWS CARIBOU ME
625 PM EST SUN DEC 22 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 MONDAY/... 625 PM UPDATE...THERE IS DEFINITELY A BREAK IN THE ACTION THIS EVENING ACROSS DOWNEAST AREAS WHERE THERE IS NOT MORE THAN SOME SPOTTY FREEZING DRIZZLE. A BIT MORE COVERAGE AND INTENSITY TO THE PRECIPITATION ACROSS NORTHERN MAINE...WITH THE PRECIPITATION FALLING IN MOST AREAS AS EITHER SNOW OR A MIX OF SNOW AND SLEET WITH A BIT OF FREEZING RAIN OBSERVED ABOUT AS FAR NORTH AS THE HOULTON/MARS HILL AREAS. THE LATEST HRRR HAS 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. NO MAJOR CHANGES TO THE ONGOING FORECAST WITH JUST A FEW TWEAKS. ONE CONCERN IS 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. 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 /MONDAY NIGHT 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 /00Z MONDAY THROUGH FRIDAY/... NEAR TERM: 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 ARE RUNNING AROUND 8 FEET AT THE EASTERN MAINE SHELF WITH A NORTH TO NORTHEAST WIND OF AROUND 20 KTS WITH GUSTS TO 25 TO 30 KTS. 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 FROM VCP 21 TO 31 EARLIER THIS EVENING TO BETTER PICK UP THE LIGHTER PRECIPITATION FALLING ACROSS THE AREA. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...FREEZING RAIN ADVISORY UNTIL 6 PM EST MONDAY FOR MEZ011- 015>017-029-030-032. WINTER WEATHER ADVISORY UNTIL 4 PM EST MONDAY FOR MEZ003>006- 010-031. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EST MONDAY FOR ANZ050>052. && $$ NEAR TERM...CB/FOISY SHORT TERM...OKULSKI LONG TERM...OKULSKI AVIATION...CB/FOISY/OKULSKI MARINE...CB/FOISY/OKULSKI EQUIPMENT...CB
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
352 PM EST SAT DEC 21 2013 .SYNOPSIS... A STRONG COLD FRONT ACCOMPANIED BY GUSTY WINDS PASSES SUNDAY. AREA RIVERS WILL BE ON THE RISE THROUGH MONDAY. AN UPPER LEVEL DISTURBANCE BRINGS SNOW SHOWERS MONDAY NIGHT INTO TUESDAY. MUCH CALMER WEATHER THE BALANCE OF THE HOLIDAY WEEK WITH BELOW NORMAL TEMPERATURES. && .NEAR TERM /THROUGH SUNDAY/... SOUTHERLY FLOW CONTINUES TO INCREASE AHEAD OF DEEPENING SFC CYCLONE WHICH IS EVIDENT BY VIEWING REGIONAL RADAR MOSAIC AS PLUME OF RAIN CONTINUES TO SHIFT NNE. DRY WEATHER HAS ALREADY REACHED NRN WV AND WRN MD AND WILL CONTINUE TO OVERSPREAD MUCH OF THE CWA THIS EVENING. PARTIAL CLEARING OVER THE NORTHERN WV MOUNTAINS HAS ALLOWED TEMPS TO SOAR INTO THE MID 70S. THIS AIR WILL MAKE IT TO THE MASON DIXON LINE...WHILE 60S SHALL ENCOMPASS WRN PA AND THE NRN WV PANHANDLE. TEMPS WILL NOT FALL MUCH TONIGHT AS BOUNDARY LAYER REMAINS WELL MIXED. COLD FRONT CROSSES SUNDAY MORNING INTO EARLY AFTERNOON. BAND OF MODERATE TO HEAVY SHOWERS WILL BE OUT AHEAD OF IT. THERMODYNAMIC PARAMETERS STILL ARE NOT OVERLY IMPRESSIVE DUE TO THE TIME OF DAY IT CROSSES. UPPER LEVEL DYNAMICS DO NOT WOW ME EITHER AS STRONG AGEOSTROPHIC FORCING RESULTING FROM JET COUPLING IS NOT PRESENT. CONTINUED TO OMIT THUNDER FROM FCST...DESPITE SPC BRINGING SLIGHT RISK TO NRN WV PANHANDLE. GUSTY WINDS UPWARDS OF 40 MPH MAY OCCUR BASED ON MOMENTUM TRANSFER. THIS COULD KNOCK AROUND OUTDOOR CHRISTMAS DECORATIONS. HRRR AGREES WITH THIS BASED ON 10M WIND GUST FIELD. HEAVY RAIN REMAINS A CONCERN ACROSS THE FLOOD WATCH AREA. AT THIS TIME...ADDITIONAL AMOUNTS UPWARDS OF AN INCH COULD LEAD TO FLOODING. THE PERIOD OF DRY WEATHER THIS EVENING HELPS OFFSET A WIDESPREAD THREAT OF HIGH WATER IN THE WATCH AREA. SIDED WITH WARMEST GUIDANCE TONIGHT. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... COLD FRONT WILL BE EAST OF OUR AREA SUNDAY NIGHT AS ANY QPF LEFT OVER ASSOCIATED WITH BAROCLINIC ZONE WILL AFFECT NRN WV MTNS AND WRN MD UNTIL MID EVENING. A BRIEF PERIOD OF CLEARING MON EVENING BEFORE CLOUDS ASSOCIATED WITH THE SURGE OF COLD AIR AND LOWER MID LVL HEIGHTS ARRIVE FROM THE WEST. MID LVL TROUGH SWEEPS THROUGH MON NGT - TUE. THIS IS ACCOMPANIED BY MUCH COLDER AIR AS H8 TEMPS PLUMMET BACK INTO THE NEGATIVE MID TEENS BY 12Z TUES. SCATTERED SNOW SHOWERS AND LAKE EFFECT SNOW SHOWERS ARE PREDICTED MON NGT INTO TUES EVENING. WIND TRAJECTORY IS NOT FAVORABLE FOR SIGNIFICANT SNOW ACCUMULATIONS. OUTSIDE THE SNOW BELT OF NWRN PA...LOOK FOR MINOR ACCUMS AT BEST GIVEN SHORT DURATION AND LACK OF FAVORABLE SNOW DYNAMICS AS NEEDED UPPER LEVEL TEMPERATURES ARE BELOW REGION OF UPWARD VERTICAL MOTION. ANTICYCLONIC FLOW RAPIDLY ENSUES DURING THE PREDAWN HOURS WEDNESDAY. THIS WILL SHUT OFF THE LAKE EFFECT MACHINE AS SCOUR OUT CLOUDS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... FOCUSED EFFORTS ON NEAR AND SHORT TERM TODAY...LATEST NUMERICAL MODELS REMAIN CONSISTENT WITH WEATHER PATTER OVER THE LONG RANGE. BELOW NORMAL TEMPS ARE PROJECTED FOR MUCH OF THE EXTENDED. PREVIOUS DISCUSSION FOLLOWS: BLDG HIGH PRES SHOULD END ANY SNOW SHWRS TUE EVE...WITH DRY WEATHER CONTG WED. A WK CLIPPER IS PROGGED FOR THU...THOUGH TIMING AND STRENGTH DIFFERENCES IN THE MDLS PRECLUDE MORE THAN A SLGT CHC MENTION FOR SNOW SHWRS ATTM. BLDG HIGH PRES IS EXPD AGAIN BY THE END OF THE WK. OVERALL...TEMPS SHOULD AVG BLO SEASONAL LVLS THRU THE PD. && .AVIATION /21Z SATURDAY THROUGH THURSDAY/... FRONTAL BOUNDARY STALLED ACROSS NW PA WILL LIFT NORTH THIS EVENING AND ALLOW FOR A BREAK IN PRECIP FOR TERMINALS SOUTH OF I80 THIS OVERNIGHT. DUJ AND FKL HOWEVER ARE MORE LIKELY TO SEE SHOWERS ONGOING THROUGH THE NIGHT WITH CONTINUED MVFR CONDITIONS. FOR SOUTHERN TERMINALS...EXPECT MAINLY VFR BY EARLY EVENING AND WITH SOUTHWESTERLY WINDS HELPING KEEP THINGS WELL MIXED OVERNIGHT...DO NOT ANTICIPATE ANY ADDITIONAL VISIBILITY RESTRICTIONS DEVELOPING. .OUTLOOK.../18Z SUNDAY THROUGH THURSDAY/... CONTINUED IFR RESTRICTIONS WILL BE POSSIBLE MONDAY NIGHT THROUGH TUESDAY NORTH OF INTERSTATE 80 DUE TO LAKE EFFECT SNOW SHOWERS. OTHERWISE...NO OTHER WIDESPREAD WEATHER RELATED AVIATION HAZARDS EXISTS. && .HYDROLOGY... A FLOOD WARNING IS IN EFFECT FOR WILLS CREEK AT CAMBRIDGE AFFECTING GUERNSEY COUNTY AND THE MUSKINGUM RIVER AT COSHOCTON AFFECTING COSHOCTON COUNTY. RAINFALL AMOUNTS OF 1.00 TO NEARLY 3.00 INCHES OF RAINFALL ARE EXPECTED OVER THE TUSCARAWAS RIVER AND MUSKINGUM RIVER BASINS. SHARP RISES ARE EXPECTED ON RIVERS AND STREAMS ACROSS EASTERN OHIO. THESE RISES WILL BE SUFFICIENT FOR THE MUSKINGUM RIVER AT COSHOCTON TO RISE ABOVE FLOOD STAGE SUNDAY AFTERNOON. WILLS CREEK WILL RISE ABOVE FLOOD STAGE SUNDAY EVENING. MINOR FLOODING IS EXPECTED AT BOTH LOCATIONS. A FLOOD ADVISORY IS IN EFFECT FOR THE OHIO RIVER AT THE POINT IN PITTSBURGH. THE OHIO RIVER IS EXPECTED TO RISE ABOVE 18.0 FEET AND BEGIN TO FLOOD THE MONONGAHELA RIVER PARKING WHARF SUNDAY AFTERNOON. THE OHIO RIVER THE CREST IS EXPECTED MONDAY AFTERNOON AT 21.8 FEET. THIS WILL COMPLETELY FLOOD THE MONONGAHELA PARKING WHARF. AT THIS TIME FLOOD WATERS ARE NOT EXPECTED TO AFFECT THE 10TH STREET BYPASS. STRONG RISES ON THE OHIO RIVER ARE FORECAST SUNDAY WITH CONTINUED ELEVATED LEVELS THROUGH TUESDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR OHZ039>041-048-057. PA...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR PAZ007>009-013. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
307 PM EST SAT DEC 21 2013 .SYNOPSIS... A STRONG COLD FRONT ACCOMPANIED BY GUSTY WINDS PASSES SUNDAY. AREA RIVERS WILL BE ON THE RISE THROUGH MONDAY. AN UPPER LEVEL DISTURBANCE BRINGS SNOW SHOWERS MONDAY NIGHT INTO TUESDAY. MUCH CALMER WEATHER THE BALANCE OF THE HOLIDAY WEEK WITH BELOW NORMAL TEMPERATURES. && .NEAR TERM /THROUGH SUNDAY/... SOUTHERLY FLOW CONTINUES TO INCREASE AHEAD OF DEEPENING SFC CYCLONE WHICH IS EVIDENT BY VIEWING REGIONAL RADAR MOSAIC AS PLUME OF RAIN CONTINUES TO SHIFT NNE. DRY WEATHER HAS ALREADY REACHED NRN WV AND WRN MD AND WILL CONTINUE TO OVERSPREAD MUCH OF THE CWA THIS EVENING. PARTIAL CLEARING OVER THE NORTHERN WV MOUNTAINS HAS ALLOWED TEMPS TO SOAR INTO THE MID 70S. THIS AIR WILL MAKE IT TO THE MASON DIXON LINE...WHILE 60S SHALL ENCOMPASS WRN PA AND THE NRN WV PANHANDLE. TEMPS WILL NOT FALL MUCH TONIGHT AS BOUNDARY LAYER REMAINS WELL MIXED. COLD FRONT CROSSES SUNDAY MORNING INTO EARLY AFTERNOON. BAND OF MODERATE TO HEAVY SHOWERS WILL BE OUT AHEAD OF IT. THERMODYNAMIC PARAMETERS STILL ARE NOT OVERLY IMPRESSIVE DUE TO THE TIME OF DAY IT CROSSES. UPPER LEVEL DYNAMICS DO NOT WOW ME EITHER AS STRONG AGEOSTROPHIC FORCING RESULTING FROM JET COUPLING IS NOT PRESENT. CONTINUED TO OMIT THUNDER FROM FCST...DESPITE SPC BRINGING SLIGHT RISK TO NRN WV PANHANDLE. GUSTY WINDS UPWARDS OF 40 MPH MAY OCCUR BASED ON MOMENTUM TRANSFER. THIS COULD KNOCK AROUND OUTDOOR CHRISTMAS DECORATIONS. HRRR AGREES WITH THIS BASED ON 10M WIND GUST FIELD. HEAVY RAIN REMAINS A CONCERN ACROSS THE FLOOD WATCH AREA. AT THIS TIME...ADDITIONAL AMOUNTS UPWARDS OF AN INCH COULD LEAD TO FLOODING. THE PERIOD OF DRY WEATHER THIS EVENING HELPS OFFSET A WIDESPREAD THREAT OF HIGH WATER IN THE WATCH AREA. SIDED WITH WARMEST GUIDANCE TONIGHT. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... COLD FRONT WILL BE EAST OF OUR AREA SUNDAY NIGHT AS ANY QPF LEFT OVER ASSOCIATED WITH BAROCLINIC ZONE WILL AFFECT NRN WV MTNS AND WRN MD UNTIL MID EVENING. A BRIEF PERIOD OF CLEARING MON EVENING BEFORE CLOUDS ASSOCIATED WITH THE SURGE OF COLD AIR AND LOWER MID LVL HEIGHTS ARRIVE FROM THE WEST. MID LVL TROUGH SWEEPS THROUGH MON NGT - TUE. THIS IS ACCOMPANIED BY MUCH COLDER AIR AS H8 TEMPS PLUMMET BACK INTO THE NEGATIVE MID TEENS BY 12Z TUES. SCATTERED SNOW SHOWERS AND LAKE EFFECT SNOW SHOWERS ARE PREDICTED MON NGT INTO TUES EVENING. WIND TRAJECTORY IS NOT FAVORABLE FOR SIGNIFICANT SNOW ACCUMULATIONS. OUTSIDE THE SNOW BELT OF NWRN PA...LOOK FOR MINOR ACCUMS AT BEST GIVEN SHORT DURATION AND LACK OF FAVORABLE SNOW DYNAMICS AS NEEDED UPPER LEVEL TEMPERATURES ARE BELOW REGION OF UPWARD VERTICAL MOTION. ANTICYCLONIC FLOW RAPIDLY ENSUES DURING THE PREDAWN HOURS WEDNESDAY. THIS WILL SHUT OFF THE LAKE EFFECT MACHINE AS SCOUR OUT CLOUDS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... FOCUSED EFFORTS ON NEAR AND SHORT TERM TODAY...LATEST NUMERICAL MODELS REMAIN CONSISTENT WITH WEATHER PATTER OVER THE LONG RANGE. BELOW NORMAL TEMPS ARE PROJECTED FOR MUCH OF THE EXTENDED. PREVIOUS DISCUSSION FOLLOWS: BLDG HIGH PRES SHOULD END ANY SNOW SHWRS TUE EVE...WITH DRY WEATHER CONTG WED. A WK CLIPPER IS PROGGED FOR THU...THOUGH TIMING AND STRENGTH DIFFERENCES IN THE MDLS PRECLUDE MORE THAN A SLGT CHC MENTION FOR SNOW SHWRS ATTM. BLDG HIGH PRES IS EXPD AGAIN BY THE END OF THE WK. OVERALL...TEMPS SHOULD AVG BLO SEASONAL LVLS THRU THE PD. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... FRONTAL BOUNDARY STALLED ACROSS NW PA WILL LIFT NORTH THROUGH THE AFTERNOON AND SHOULD ALLOW FOR A BREAK IN PRECIP FOR TERMINALS SOUTH OF I80 THIS EVENING AND OVERNIGHT. DUJ AND FKL HOWEVER ARE MORE LIKELY TO SEE SHOWERS ONGOING THROUGH THE NIGHT WITH CONTINUED MVFR CONDITIONS. FOR SOUTHERN TERMINALS...EXPECT MAINLY VFR BY LATE THIS AFTERNOON AND OVERNIGHT...AND WITH SOUTHWESTERLY WINDS HELPING KEEP THINGS WELL MIXED OVERNIGHT...;DO NOT ANTICIPATE ANY ADDITIONAL VISIBILITY RESTRICTIONS DEVELOPING. .OUTLOOK.../18Z SUNDAY THROUGH THURSDAY/... IFR RESTRICTIONS ARE POSSIBLE MON NGT INTO TUE ACROSS FKL AND DUJ WITH LAKE EFFECT SNOW SHOWERS. BRIEF MVFR RESTRICTIONS COULD AFFECT PIT AND LBE DURING THE AFOREMENTIONED TIME FRAME AS WELL. OTHERWISE...NO OTHER WIDESPREAD WEATHER RELATED AVIATION HAZARDS EXISTS. && .HYDROLOGY... A FLOOD WARNING IS IN EFFECT FOR WILLS CREEK AT CAMBRIDGE AFFECTING GUERNSEY COUNTY AND THE MUSKINGUM RIVER AT COSHOCTON AFFECTING COSHOCTON COUNTY. RAINFALL AMOUNTS OF 1.00 TO NEARLY 3.00 INCHES OF RAINFALL ARE EXPECTED OVER THE TUSCARAWAS RIVER AND MUSKINGUM RIVER BASINS. SHARP RISES ARE EXPECTED ON RIVERS AND STREAMS ACROSS EASTERN OHIO. THESE RISES WILL BE SUFFICIENT FOR THE MUSKINGUM RIVER AT COSHOCTON TO RISE ABOVE FLOOD STAGE SUNDAY AFTERNOON. WILLS CREEK WILL RISE ABOVE FLOOD STAGE SUNDAY EVENING. MINOR FLOODING IS EXPECTED AT BOTH LOCATIONS. A FLOOD ADVISORY IS IN EFFECT FOR THE OHIO RIVER AT THE POINT IN PITTSBURGH. THE OHIO RIVER IS EXPECTED TO RISE ABOVE 18.0 FEET AND BEGIN TO FLOOD THE MONONGAHELA RIVER PARKING WHARF SUNDAY AFTERNOON. THE OHIO RIVER THE CREST IS EXPECTED MONDAY AFTERNOON AT 21.8 FEET. THIS WILL COMPLETELY FLOOD THE MONONGAHELA PARKING WHARF. AT THIS TIME FLOOD WATERS ARE NOT EXPECTED TO AFFECT THE 10TH STREET BYPASS. STRONG RISES ON THE OHIO RIVER ARE FORECAST SUNDAY WITH CONTINUED ELEVATED LEVELS THROUGH TUESDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR OHZ039>041-048-057. PA...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR PAZ007>009-013. WV...NONE. && $$ SYNOPSIS...98 NEAR TERM...98 SHORT TERM...98 LONG TERM...98/07 AVIATION...88
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
338 PM EST SAT DEC 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 457 AM EST SAT DEC 21 2013 SW FLOW ALOFT BTWN UPPER LOW OVER HUDSON BAY AND STRONG SOUTHERN STREAM DISTURBANCE OVER NEW MEXICO. THROUGH TONIGHT...MAIN ISSUES ARE TIED TO LAKE EFFECT. SOUTHERN STREAM WAVE LIFTS TOWARD UPPER GREAT LAKES LATER TONIGHT...THOUGH IT APPEARS MAJORITY OF WIDESPREAD SNOW WITH THE DEVELOPING LOW PRESSURE SYSTEM WILL REMAIN JUST SOUTH OF CWA UNTIL DAYBREAK ON SUNDAY. EMBEDDED SHORTWAVES/PV ANOMALIES IN FLOW ALOFT HELPING TO SUSTAIN LGT SNOW/FLURRIES OVER CWA EARLY THIS MORNING. ALSO A BAND OF ENHANCED LK EFFECT MAINLY OVER SCNTRL AND SOUTHEAST PORTIONS OF LK SUPERIOR. RAP...WHICH DOES HAVE DECENT HANDLE ON BACK EDGE OF LGT SNOW CURRENTLY...INDICATES MID-LEVEL MOISTURE/UVM EXITS EAST HALF OF CWA THROUGH AROUND DAYBREAK THIS MORNING SO WOULD EXPECT LGT SNOW TO END FOR A TIME. AT THE LEAST THE CLOUDS WILL CONTINUE TO HOLD UP TEMPS THIS MORNING MAINLY IN THE TEENS. MILD FOR SURE COMPARED TO THE RECENT CHILL UPR LAKES HAS EXPERIENCED. CURRENTLY THERE IS A SFC TROUGH ACROSS THE AREA EXTENDING TO THE NW OF SFC LOW NEAR DETROIT. EXPECT TROUGHING TO PERSIST THROUGH MUCH OF THE DAY WHILE GRADUALLY GETTING PUSHED TO THE SOUTH AND EAST BY THIS AFTN AS HIGH PRESSURE OVR SASKATCHEWAN AND MANITOBA TRIES TO RIDGE ACROSS LK SUPERIOR REGION. THE MAIN IMPACT THIS HAS IS ON WIND FIELDS AND ASSOCIATED LAKE EFFECT AS THERE IS ENOUGH INSTABILITY WITH INVERSIONS UP TO 5-7KFT AND TEMPS AT INVERSION TOP AROUND -13C WHILE WATER TEMPS ARE AROUND +3C. SOUNDINGS AT P59/CMX AND STDM4 INDICATE DECENT SUBSIDENCE ABOVE MOIST LAKE EFFECT LAYER AND ALSO NOT AS MUCH LIFT WITHIN THE DGZ. IF CONVERGENCE CAN PERSIST OVER THE KEWEENAW TODAY...THEN THERE IS AN OPPORTUNITY FOR ADVY LEVEL SNOW AMOUNTS. CONFIDENCE IS LOW ON THIS POTENTIAL AND EVEN LOWER ON EXACTLY WHERE THAT WOULD OCCUR. FOLLOWED GEM-REGIONAL THROUGH TODAY FOR WINDS ALONG WITH NAM AND LOCAL-WRF MODEL BASED ON RAP BOUNDARY CONDITIONS. THIS BLEND ESSENTIALLY HANGS UP MAIN CONVERGENCE AREA OVER NORTHERN KEWEENAW THEN EVENTUALLY DRAWS IT SOUTH ACROSS THE PENINSULA THIS AFTN AS THE HIGH BUILDS TOWARD LK SUPERIOR. SINCE INSTABILITY IS NOT EXTREME OR OVER THE TOP BY ANY MEANS...FCST SNOW AMOUNTS FROM 2-4 INCHES...GREATEST NEAR MOHAWK/EAGLE RIVER/COPPER HARBOR. DESPITE MODELS NOT SHOWING MUCH OCCURRING FOR OTHER AREAS WHERE FLOW IS ONSHORE NEAR LK SUPERIOR...WENT WITH PERSISTENCE AND KEPT MENTION OF SNOW OVER FAR WESTERN UPR MICHIGAN AND ALSO IN NCNTRL UPR MICHIGAN. ANY AMOUNTS FOR THESE AREAS TODAY WILL JUST A DUSTING OF LESS THAN 1 INCH. MINOR ISSUE FOR TODAY IS SKY COVER AND TEMPS. MODELS STRUGGLING WITH EVENTUAL EVOLUTION OF LOW MVFR CLOUDS FM LK SUPERIOR BACK INTO CNTRL MINNESOTA. NAM/RAP/GEM-REGIONAL SHOW THESE CLOUDS TO START BUT SEEM TOO QUICK TO GET RID OF THEM OVER ALL BUT WESTERN CWA BY LATER MORNING. WE WILL SEE ON THIS. IF MORE SUN OCCURS...MAX TEMPS MAY PUSH WELL INTO THE MID-UPR 20S CNTRL. BASED ON CURRENT SATELLITE/OBS TRENDS AND WITH SUN ANGLE ABOUT AS LOW AS IT GETS...WILL KEEP SKIES MOSTLY CLOUDY FOR TODAY. LATER TODAY WILL BE A MOOT POINT AS INCREASING NE WINDS SHOULD RESULT IN EXPANSION OF CLOUDS OFF LK SUPERIOR. SOUTHERN STREAM WAVE/LOW PRESSURE SYSTEM AFFECTS WILL BE KNOCKING ON THE DOOR OF UPR MICHIGAN SO TO SPEAK LATER TONIGHT. NAM/GFS/ECMWF LOOKED SIMILAR WITH PLACEMENT OF H5 TROUGH/PRIMARY PV ANAMOLY/H85 AND SFC LOWS. GEM WAS FARTHER NORTH WITH H85 LOW. SEEMED THAT ECMWF WAS A NICE MIDDLE GROUND BTWN FARTHER SOUTH NAM/GFS WITH ADVANCING WIDESPREAD SNOW AND MORE AGRESSIVE GEM. BROUGHT LIKELY POPS FOR SYNOPTIC SNOW INTO FAR SCNTRL BY 09Z SUNDAY. OTHER IMPACT WILL BE INCREASING FAVORABLE LAKE EFFECT OVER FAR WEST/KEWEENAW AND NCNTRL CWA. NOT EXPECTING A LOT OF SNOW AS ANY LARGE SCALE FORCING IS MINIMAL THROUGH 12Z...BUT THERE IS ENOUGH EVIDENCE IN FCST SOUNDINGS THAT LAKE EFFECT WILL BE DEVELOPED ENOUGH TO RESULT IN LIKELY POPS WITH MINOR SNOW AMOUNTS. SETUP BECOMES MUCH MORE FAVORABLE FOR SIGNIFICANT LAKE ENHANCEMENT FOR SUNDAY AND BEYOND. BTWN THE LAKE EFFECT MOISTURE/SNOW AND MID-HIGH CLOUDS ARRIVING FROM THE SOUTH...EXPECT TEMPS TONIGHT TO STAY IN THE TEENS AGAIN. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 337 PM EST SAT DEC 21 2013 A LOW PRESSURE SYSTEM MOVING THROUGH THE SRN GREAT LAKES REGION SUN...WHICH WILL BRING SYNOPTIC SNOW TO THE FAR SERN CWA AND LAKE ENHANCED SNOW TO MUCH OF THE REST OF THE CWA THROUGH SUN. WITH THE LONG TERM FORECAST STARTING AT 00Z MON...ALMOST ALL OF THE SYNOPTIC PRECIP ASSOCIATED WITH THE PREVIOUSLY MENTIONED LOW WILL BE E OF THE CWA. MORE SYNOPTIC SNOW WILL BE OVER OR JUST W OF THE FAR WRN CWA AT 00Z MON ASSOCIATED WITH A DEEP UPPER TROUGH OVER MN. THE TROUGH WILL MOVE TO THE CENTRAL CWA BY 00Z TUE THEN E OF THE CWA BY 06Z TUE. MODELS ARE IN GOOD AGREEMENT ON THE TROUGH WITH THE EXCEPTION OF THE 12Z/21 NAM WHICH HAS THE TROUGH DEEPER AND NEGATIVELY TILTED AND SEEMS TOO AMPLIFIED. SHOULD SEE AN INVERTED SFC TROUGH STRETCHING FROM THE SE ACROSS LAKE SUPERIOR THROUGH MUCH OF TUE NIGHT BEFORE A SFC AND UPPER RIDGE MOVE ON ON TUE. LAKE ENHANCED SNOW WILL BE ONGOING IN THE NNE-NE LOW LEVEL FOR AT 00Z MON WITH 850MB TEMPS AROUND -15C. WIND FIELDS SHOULD ONLY BACK SLIGHTLY THROUGH MON...THEN MORE QUICKLY ON MON NIGHT...SO THE PRIMARY AREAS FAVORED BY THE LAKE ENHANCEMENT WILL BE MARQUETTE AND BARAGA COUNTIES AS WELL AS GOGEBIC AND ONTONAGON COUNTIES. MODERATE TO HEAVY SNOW IS EXPECTED OVER THE WRN FAVORED AREAS THROUGH MON...AND INTO MON NIGHT OVER THE NCENTRAL. IN COORDINATION WITH SHORT TERM FORECASTER...LAKE EFFECT SNOW ADVISORIES WERE ISSUED FOR THESE TWO AREAS. GENERALLY...EXPECT SNOW TO BY STEADY...WITH ADDITIONAL SNOWFALL AMOUNTS SUN NIGHT INTO MON NIGHT OF AROUND A FOOT OVER THE FAR WRN U.P. AND 8-12 INCHES OVER THE NCENTRAL. MAINLY FOCUSED ON THE PREVIOUSLY DISCUSSED SHORTER TERM OF THE FORECAST...BUT WILL BRIEFLY SUMMARIZE MORE SIGNIFICANT CHANGES TO THIS PART OF THE FORECAST. KEPT POPS HIGHER THAN CONSENSUS FOR TUE NIGHT THROUGH THU AS LAKE EFFECT AND ENHANCED SNOW IS NOT CAPTURED WELL BE LOW RES MODELS. A COUPLE OF PERIODS OF COLDER WEATHER ARE IN STORE...FOR SUN NIGHT THROUGH TUE AND WED NIGHT THROUGH FRI NIGHT...THE LOWEST TEMPS SHOULD BE MON NIGHT AND THU NIGHT WHERE TEMPERATURES MAY FALL INTO THE TEENS BELOW ZERO INTERIOR W AND FAR E ON MON NIGHT AND OVER THE INTERIOR W ON THU NIGHT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1243 PM EST SAT DEC 21 2013 KIWD...LIGHT WINDS BECOMING ONSHORE NE DIRECTION SHOULD ENSURE MVFR CIGS AND LIGHT LAKE SNOW SHOWERS ACROSS THE TAF SITES BY LATE THIS AFTERNOON. IFR VSBY IN SNOW AND BLSN IS EXPECTED TO DEVELOP AT WRN TAF SITES LATE TONIGHT ESPECIALLY AS NE WINDS AND INSTABILITY INCREASES OVER WRN LAKE SUPERIOR. WINDS BECOMING MORE EASTERLY WILL SCATTER OUT THE LOW CLOUDS AT SAW LATE TONIGHT. WIDESPREAD SNOW IS EXPECTED TO IMPACT ALL TERMINALS ON SUNDAY AS A LOW PRESSURE SYSTEM SLIDES ACROSS THE CENTRAL GREAT LAKES REGION. HEAVIEST SNOW WILL OCCUR AT IWD WITH UPSLOPE NORTHEAST WINDS PROVIDING ADDITIONAL SUPPORT FOR SNOW OFF LK SUPERIOR. AS A RESULT...VSBYS AT KIWD COULD LOWER TO LIFR BY LATE SUNDAY MORNING. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 457 AM EST SAT DEC 21 2013 LIGHT WINDS TODAY WITH TROUGH OVER THE LAKE THEN AS THE TROUGH SINKS SOUTH TONIGHT...EXPECT STRONG AND GUSTY NORTHEAST WINDS TO 30 KTS OVER MUCH OF LAKE SUPERIOR INTO SUNDAY...FURTHER STRENGTHENED BY LOW PRESSURE LIFTING ACROSS LOWER MICHIGAN. COULD BE GALE GUSTS OVER THE WEST WITH CHANNELING BETWEEN MINNESOTA SHORELINE AND KEWEENAW PENINSULA. DURING THIS PERIOD OF STRONGER WINDS THERE WILL BE FREEZING SPRAY. EXPECT THE LOW TO LINGER A SURFACE TROUGH OVER THE UPPER GREAT LAKES THROUGH MONDAY AND KEEP WINDS UP TO 25 KTS. HIGH PRESSURE WILL CROSS THE UPPER GREAT LAKES ON MONDAY NIGHT...WHILE A LOW PRESSURE SYSTEM BEGINS TO TAKE SHAPE IN THE CANADIAN PRAIRIES. THIS LOW WILL LEAD TO INCREASING SOUTHERLY WINDS ACROSS LAKE SUPERIOR ON TUESDAY. WHEN THE LOW MOVES THROUGH THE REGION ON WEDNESDAY...WINDS WILL BECOME WESTERLY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 9 AM TO 5 PM EST SUNDAY FOR MIZ007- 013-014-085. LAKE EFFECT SNOW ADVISORY FROM 1 AM EST /MIDNIGHT CST/ SUNDAY TO MIDNIGHT EST /11 PM CST/ MONDAY NIGHT FOR MIZ002-009. WINTER WEATHER ADVISORY FROM 5 AM TO 2 PM CST SUNDAY FOR MIZ012. LAKE EFFECT SNOW ADVISORY FROM 7 AM SUNDAY TO 7 AM EST TUESDAY FOR MIZ004-005. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING FROM 6 AM EST /5 AM CST/ TO 3 PM EST /2 PM CST/ SUNDAY FOR LSZ162. HEAVY FREEZING SPRAY WARNING FROM 7 AM SUNDAY TO 7 AM EST MONDAY FOR LSZ263-264. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...TITUS AVIATION...VOSS MARINE...JLA
AREA FORECAST DISCUSSION
NWS GAYLORD MI
216 PM EST SAT DEC 21 2013 .SYNOPSIS... ISSUED AT 457 AM EST SAT DEC 21 2013 QUIET WEATHER IS EXPECTED DURING THE DAY TODAY BEFORE ANOTHER STORM SYSTEM AFFECTS THE REGION TONIGHT INTO SUNDAY. THIS EVOLVING SYSTEM WILL LIFT INTO THE NORTHERN OHIO VALLEY SATURDAY NIGHT...BRINGING LIGHT TO MODERATE AMOUNTS OF SNOW TO THE REGION. COLD AIR WILL FILTER BACK INTO THE GREAT LAKES MONDAY AND TUESDAY...GENERATING SOME LAKE EFFECT SNOW...ACROSS PARTS OF NORTHERN MICHIGAN TO BEGIN THE UPCOMING WORK WEEK. A COUPLE OF ALBERTA CLIPPERS WILL THEN LIKELY BRINGING SOME LIGHT SNOW FOR CHRISTMAS DAY AND A CHANCE FOR LIGHT SNOW ON THURSDAY. && .UPDATE... ISSUED AT 215 PM EST SAT DEC 21 2013 NO BIG CHANGES...HAVE DECREASED SKY COVER ACROSS EASTERN UPPER MICHIGAN WITH FILTERED SUN UP THAT WAY. REMAINS TO BE SEEN IF SOME OF THAT LOW LEVEL CLEARING CAN GET DOWN INTO THE TIP OF THE MITT COUNTIES OR NOT. WILL SEE. OTHERWISE...PATCHY FREEZING DRIZZLE APPEARS TO HAVE ENDED AND CIGS ARE COMING UP A BIT...THUS NO NEED TO EXTEND -FZDZ AT THIS POINT. TO OUR SOUTH...INVERTED SFC TROUGH STRETCHES FROM THE WESTERN GULF UP THROUGH NEW ENGLAND WITH WIDESPREAD PRECIP ALREADY OCCURRING ALONG THAT CONVERGENCE AXIS. ANTICIPATED STRONG SHORT WAVE MOVING THE NRN TEXAS AND ABOUT TO SWING UP THROUGH THE CENTRAL PLAINS AND INTO THE MIDWEST TONIGHT THEN SWING UP THROUGH LOWER MICHIGAN DURING THE DAY. SFC LOW ON TRACK TO SPIN UP ALONG THE BAROCLINIC ZONE AND ADVANCE UP THROUGH NRN OHIO/FAR SE LOWER MICHIGAN EARLY SUNDAY MORNING BEFORE KICKING INTO THE EASTERN GREAT LAKES THROUGH THE DAY. ONGOING WARM CONVEYOR PRECIP ALREADY TO OUR SOUTH WILL INITIALLY PUSH UP INTO PARTS OF NRN LOWER MICHIGAN LATER TONIGHT BEFORE GETTING PINCHED OFF AND KICKED INTO THE EASTERN LAKES SUNDAY...FOLLOWED BY A PERIOD OF HEAVIER WRAP AROUND/ DEFORMATION SNOW THROUGH THE DAY SUNDAY...PERIOD OF HEAVIEST SNOW BETWEEN 15Z AND 21Z AS THE SHORT WAVE SWINGS UP THROUGH LOWER MICHIGAN. LITTLE HAS CHANGED WITH THIS SCENARIO AMONGST GUIDANCE SOLUTIONS OVER THE LAST DAY...AND THE NAM SOLUTION IS STILL THE FURTHER NORTHERN SOLUTION...TRACKING THE SFC LOW INTO THE THUMB BUT INTERESTINGLY KEEPS WARM NOSE ALOFT (>0C LAYER) JUST OUT OF THIS CWA. SO ALL GUIDANCE SOURCES GIVE NRN LOWER MICHIGAN SNOW...WITH JUST AN OUTSIDE CHANCE OF SLEET OVER THE FAR SE COUNTIES TOWARD SAGINAW BAY. ONLY MAIN DIFFERENCES AT THIS POINT IS JUST WHERE HEAVIEST WRAP AROUND QPF BULLSEYE TRACKS THROUGH THE REGION... AGAIN WITH THE NAM A LITTLE FURTHER NORTHWARD DISPLACED. BUT OUR CONSENSUS FORECAST KEEPS HEAVIEST QPF BULLSEYE TRACKING RIGHT UP ACROSS NRN LOWER MICHIGAN...POSSIBLY SKIMMING FAR EASTERN UPPER MICHIGAN WITH SOME HEAVIER SNOW. AS FAR AS SNOW AMOUNTS GO...BASICALLY HAVE A 2 PERIOD (TONIGHT AND TOMORROW) COMBINED TOTAL OF 0.4 TO 0.6 INCHES TOTAL LIQUID OVER NRN LOWER MICHIGAN...0.2 TO 0.4 INCHES IN EASTERN UPPER MICHIGAN. SNOW ACCUMULATIONS WILL OF COURSE BE DEPENDENT ON JUST WHAT SNOW:WATER RATIOS ARE REALIZED. HAVE <10:1 RATIOS OVER THE S/SE COUNTIES AND 10-15:1 FOR NRN HALF OF THE CWA...YIELDING A NICE 4 TO 7 INCHES SWEET SPOT CENTERED UP THROUGH NRN LOWER MICHIGAN AND LESSER AMOUNTS TOWARD SAGINAW BAY. NOT MUCH DIFFERENT WITH WHAT WE HAVE BEEN FORECASTING FOR THE LAST DAY OR TWO. PLAN NO CHANGES TO THE CURRENT WINTER WEATHER ADVISORIES...ALTHOUGH WE MAY PUT EASTERN UPPER MICHIGAN INTO AN ADVISORY FOR SOME BEEFIER SNOWFALL OVER THE EASTERN PART OF THOSE COUNTIES. UPDATE ISSUED AT 1028 AM EST SAT DEC 21 2013 NO MAJOR CHANGES TO THE FORECAST AT THIS HOUR...AND AN OVERALL QUIET...ALBEIT CLOUDY DAY ON TAP FOR THE NORTH WOODS. 12Z APX REVEALING A FAIRLY DEEP SATURATED LOW LAYER UP TO NEARLY 750 MB...ALTHOUGH THE TEMP/DEWPOINT SPREAD DOES OPEN A BIT IN LAYERS. NONETHELESS...HAVE HAVE A FEW REPORTS OF -FZDZ AROUND THE TVC AREA AND OBS AROUND THE GRAND TRAVERSE BAY AREA DOES HINT AT PATCHY FZDZ VIA REDUCED VSBYS AND LOW CIGS. EVEN GLR REPORTING LOW VSBY AND FZFG. SO...HAVE ADDED PATCHY -FZDZ TO THE FORECAST THROUGH THE MORNING AND EVEN ISSUED AN SPS TO COVER SOME POTENTIAL SLICK SPOTS/BLACK ICE THIS MORNING. RUC FORECAST SOUNDINGS SHOW ONGOING LOW LEVEL DRYING/OPENING THE SOUNDINGS JUST A BIT THROUGH THE AFTERNOON...SUGGESTING -FZDZ WILL END. WILL SEE. OTHERWISE...JUST INGESTING OBSERVATIONAL TRENDS AND INCOMING 12Z GUIDANCE TO SEE WHAT...IF ANY ADJUSTMENTS MAY BE NEEDED TO THE UPCOMING EVENT LATER TONIGHT THROUGH SUNDAY. NO BIG SURPRISES SO FAR. UPDATE ISSUED AT 628 AM EST SAT DEC 21 2013 UPDATED SKY GRIDS. WINDS ARE TURNING LIGHT OUT OF THE NORTH WITH LITTLE TO NO SPEEDS REMAINING 5 KTS OR LESS. SLOWED ANY SORT OF GOOD LOW LEVEL DRYING AND AM KEEPING LOW CLOUDS AROUND THROUGH A GOOD PORTION OF THE DAY...PLUS A PLETHORA OF MID AND HIGH LEVEL CLOUDS REMAINS OVER MUCH OF THE REGION AND DO NOT SEE MUCH HAPPENING WITH THAT TODAY. THUS...CLOUDY FOR MOST OF THE DAY...THIS IS ESPECIALLY TRUE ACROSS THE SE CWA WHERE LOW LEVEL MOISTURE WILL BE RICH/THICK ENOUGH FOR CLOUDS. NO PRECIPITATION EXPECTED FOR THE DAY. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 457 AM EST SAT DEC 21 2013 CURRENTLY...SPLIT FLOW IN THE UPPER LEVELS WITH A NRN STREAM JET STREAK OVERHEAD...AND A SRN STREAM JET STREAK LIFTING INTO OK WHICH IS EJECTED FROM A CUT OFF LOW OVER FAR WEST TX. IN THE NRN STREAM...WE HAVE ONE WEAK AND SHEARED OUT VORT MAX RUNNING INTO EASTERN LAKE SUPERIOR...WHICH HAS CONTINUED TO PRODUCE LIGHT SNOW/FLURRY RETURNS ON MQT RADAR WHICH WERE WORKING UP THROUGH WESTERN SECTIONS OF CHIP/MACK COUNTIES OF EASTERN UPPER. H8 LLJ FORCING IS COMPLETELY DONE AS WIND DIRECTIONS HAVE VEERED WEST...AND ACTUALLY DRYING WAS UNDERWAY FROM NORTH TO SOUTH. THIS ALSO HELPING TO KEEP ANY LIGHT SNOW AT BAY ACROSS EASTERN UPPER. PECULIAR EARLIER WEAK RADAR RETURNS EMANATING FROM ANTRIM INTO CRAWFORD COUNTY HAS BEEN A VERY FINE LIGHT SNOW...AND THIS WAS ALSO ERODING...LIKELY DUE TO THE NOW H8 DRYING. TOTAL MOISTURE IN THE COLUMN IS DRYING...AND WILL NOW BE SLOWLY ERODING ANY CHANCE OF PRECIP AND PATCHY FREEZING DRIZZLE...THE LATTER OF WHICH SEEMS TO BE ISOLATED AT BEST...WITH ONLY CADILLAC OBSERVATION SUGGESTING THE POSSIBILITY OF FREEZING DRIZZLE...AND ACTUALLY BELIEVE THAT IS MORE OF A LOWERING CEILING/FREEZING FOG TYPE THING. DO NOT BELIEVE THAT THIS IS ANY SERIOUS IMPACT. TODAY AND TONIGHT...WEAK/SHEARED OUT VORT MAX WILL EXIT EAST OVER THE NEXT COUPLE OF HOURS WITH H8 DRYING CONTINUING TO SLIDE SOUTH...ENDING ALL LIGHT SNOW IN EASTERN UPPER. WINDS DO VEER MORE NORTHERLY INTO THE DAYLIGHT HOURS...AND LOW LEVEL TEMPS RESULT IN DELTA T`S SUFFICIENT ENOUGH FOR MAYBE A FEW FLURRIES ACROSS FAR NE LOWER. OUTSIDE OF THAT...A QUIET PERIOD OF WEATHER FOR THE DAY...WITH DEEP SW FLOW ALOFT...ABOVE THE SHALLOW COLDER AIR. THIS WILL CONTINUE TO BRING IN MIDDLE AND UPPER LEVEL CLOUDS. DO NOT SEE THE NORTHERLY FLOW BEING STRONG ENOUGH TO SCOUR OUT THE LOW LEVEL CLOUDS ACROSS THE SE PART OF THE CWA. THIS WILL RESULT IN A RETURN A DEEPLY SATURATED ATMOSPHERE IN THE AFTERNOON. WE WILL SEE SOME WEAK ENERGY EJECTED FROM THE SRN STREAM CUT OFF WORKING IN OVER THE FAR SE CWA LATE IN THE AFTERNOON FOR THE FIRST CHANCES FOR SEEING SOME LIGHT SNOW FALL. STRONGER ENERGY/MODERATE DEEP LAYER -DIVQ ARRIVES OVERNIGHT...AS THE ATMOSPHERE DEEPENS IN MOISTURE. THIS WILL MAINLY BE ACROSS NRN LOWER. THE DEEP MOISTURE IS BROUGHT IN BY A WIDE OPEN GULF (CURRENTLY STREAMING DEEP LOW LEVEL MOISTURE INTO THE OHIO RIVER VALLEY) ARRIVES VIA STRONG LOW LEVEL JET. AS THE SRN STREAM CUT OFF OPENS UP AND LIFTS INTO ILLINOIS LATE TONIGHT/DAYBREAK TOMORROW...THE SFC LOW DEEPENS SOME...AND WINDS BACK...ALLOWING THE BEST LOW LEVEL MOISTURE TURN GET LIFTED FURTHER NORTH INTO OUR NECK OF THE WOODS. AT THE SAME TIME...STRONG DEEP LAYER -DIVQ IS SETTLED IN ON US...AND SNOWS WILL PICK UP IN INTENSITY. CAN SEE AROUND A COUPLE OF INCHES BY DAYBREAK ACROSS THE SE CWA...LESSENED NEAREST THE SAG BAY BY LOW LIQUID-SNOW RATIOS AND THE POSSIBILITY (IF WARMER NAM IS RIGHT) OF A MIX WITH SLEET. FOR A DISCUSSION ON THE WATCH SITUATION...SEE BELOW. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 457 AM EST SAT DEC 21 2013 AN ACTIVE WEATHER PATTERN ALONG WITH COLD TEMPERATURES CONTINUE THROUGH THE FORECAST PERIOD WITH A MEAN TROUGH REMAINING IN PLACE ACROSS CENTRAL CANADA INTO THE GREAT LAKES REGION. IN ADDITION...UPPER LEVEL DISTURBANCES MOVING THROUGH THE FLOW ALOFT WILL BRING NUMEROUS CHANCES FOR SNOW SHOWERS...ENHANCED FROM TIME TO TIME BY THE BIG LAKES. MEANWHILE...THE WELL ADVERTISED SOUTHERN JET STREAM SYSTEM COULD STILL POTENTIALLY BRING WHAT LOOKS LIKE A MODERATE AMOUNT OF SNOW TO REGION LATER SATURDAY NIGHT INTO SUNDAY. THE MAIN LONG TERM FORECAST CONCERNS REVOLVE AROUND SNOW AMOUNTS FOR SATURDAY NIGHT INTO SUNDAY THEN THE USUAL SUSPECTS...POPS AND TEMPERATURES FOR THE REMAINDER OF THE FORECAST. SUNDAY...SOUTHERN BRANCH ENERGY MOVES NORTHWARD ALONG A TIGHTENING BAROCLINIC ZONE. LATEST MODEL RUNS CONTINUE TO HAVE A MODEST AREA OF LOW PRESSURE AT THE SURFACE TRACKING ACROSS EITHER NORTHERN OHIO (MAJORITY OF MODELS) OR SOUTHWEST LOWER MICHIGAN (INCONSISTENT AND CONTINUED OUTLIER NAM). THERE IS STILL THE POTENTIAL FOR LAKE ENHANCEMENT OFF OF LAKE HURON ACROSS NORTHEAST LOWER AS A POCKET OF COLDER AIR (850 MB TEMPS -10 TO -12 C) TRIES TO SYNC UP WITH THE TAIL END OF DEEP SYNOPTIC MOISTURE. OVERALL...A GENERAL LIGHT TO MODERATE SNOWFALL IS STILL EXPECTED WITH STORM TOTAL AMOUNTS OF BETWEEN 4 AND 8 INCHES OF GREASY SNOW WHICH WILL BE COVERED WITH A WINTER WEATHER ADVISORY FOR ALL COUNTIES OF NORTHERN LOWER MICHIGAN. WILL STILL HAVE TO BE COGNIZANT OF POSSIBLE SNEAKY LAKE ENHANCEMENT ADDING TO THE TOTALS ACROSS NORTHEAST LOWER. MEANWHILE...ACROSS EASTERN UPPER...2 TO 3 INCHES OF ACCUMULATION IS EXPECTED. HIGHS RANGING FROM THE UPPER TEENS TO MIDDLE 20S...BUT LIKELY FALLING OFF IN THE AFTERNOON AS COLD AIR ADVECTION KICKS IN. SUNDAY NIGHT...WRAP AROUND MOISTURE/DEFORMATION ZONE AXIS SITS OVER THE REGION. THIS WILL LIKELY BRING SOME LIGHT SNOW...WITH ADDITIONAL ACCUMULATIONS OF ONE TO PERHAPS TWO INCHES. LOWS RANGING FROM THE COLDER SINGLE DIGITS ABOVE ZERO TO THE MIDDLE TEENS. MONDAY AND MONDAY NIGHT...A NORTHERN STREAM TROUGH ALONG WITH ANOTHER SHOT OF ARCTIC AIR (850 MB TEMPS DOWN TO -20 C OR SO) DROPS DOWN INTO THE REGION BRINGING ADDITIONAL CHANCES FOR MAINLY LIGHT SNOW. THE FLOW IS RATHER LIGHT OVERALL BUT MAY STILL BE JUST STRONG ENOUGH TO PRODUCE SOME LAKE EFFECT (GENERALLY OUT OF THE NORTH NORTHWEST). HOWEVER...AM NOT EXPECTING BIG TIME ACCUMULATIONS WITH MODEL SOUNDINGS SHOWING INVERSION HEIGHTS OF ONLY AROUND 3000 FEET OR SO PLUS SNOWFLAKE SIZES WILL LIKELY BE RATHER SMALL. HIGHS MAINLY IN THE TEENS. LOWS RANGING FROM THE COLDER SINGLE DIGITS TO THE MIDDLE TEENS. TUESDAY...PERHAPS SOME LINGERING NORTH NORTHWEST FLOW LAKE EFFECT IN THE MORNING. OTHERWISE...ARCTIC HIGH PRESSURE PRESSES DOWN FROM THE NORTH YIELDING VERY COLD TEMPERATURES AND PERHAPS CLEARING SKIES (IF WE CAN SCOUR OUT THE LIKELY STUBBORN STRATUS). HIGHS ONLY EXPECTED TO RANGE FROM THE UPPER SINGLE DIGITS (ABOVE ZERO) TO THE MIDDLE TEENS. LOWS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO AT NIGHT. WEDNESDAY THROUGH FRIDAY...A PARADE OF SHORT WAVES DROP DOWN THROUGH THE FLOW. EXTENDED MODELS CONTINUE TO VARY ON THE EXACT TIMING AND DETAILS SO WILL NOT GET TOO FANCY...AND HAVE GENERAL CHANCES FOR SNOW SHOWERS. THERE COULD BE SOME LAKE ENHANCEMENT AS WELL FROM TIME TO TIME...BUT PINNING DOWN THE EXACT FLOW REGIMES IS NEARLY IMPOSSIBLE THIS FAR OUT. HIGHS IN THE MIDDLE TO UPPER 20S WEDNESDAY THEN COOLING OFF AGAIN INTO THE UPPER TEENS TO MIDDLE 20S FOR THURSDAY AND THE MIDDLE TEENS TO AROUND 20 FOR FRIDAY. LOWS IN THE TEENS WEDNESDAY NIGHT THEN THE SINGLE DIGITS FOR THURSDAY AND FRIDAY NIGHTS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 215 PM EST SAT DEC 21 2013 CIGS HAVE SLOWLY INCREASE ACROSS NRN LOWER MICHIGAN OVER THE LAST FEW HOURS...WITH ALL TERMINAL SITES MVFR OR BETTER. CONDITIONS WILL LARGELY REMAIN UNCHANGED THROUGH THIS EVENING. SNOWFALL WILL BEGIN TO NUDGE INTO THE REGION SOUTH-NORTH LATE TONIGHT REACHING THE TAF SITES BETWEEN 08Z AND 12Z. CIGS/VSBYS WILL LOWER TO LOW MVFR OR IFR AND REMAIN THERE THROUGH MUCH OF SUNDAY. LIGHT NORTHEASTERLY WINDS THROUGH THIS AFTERNOON. BUT NE-E WINDS INCREASE TONIGHT AND BECOME A BIT GUSTY FOR SUNDAY (GUSTS INTO THE 20 TO 25 KNOT RANGE) AS LOW PRESSURE TRACKS BY TO OUR SOUTH. && .MARINE... ISSUED AT 457 AM EST SAT DEC 21 2013 A LIGHT EASTERLY WINDS REGIME WILL BRIEFLY TURN NORTHERLY OVER MANY OF THE NEARSHORE WATERS THIS MORNING...BEFORE RETURNING TO EASTERLY AND INCREASING THROUGH TONIGHT. THIS DUE TO STRENGTHENING LOW PRESSURE THAT WILL LIFT THROUGH DETROIT. A PERIOD OF ADVISORY LEVEL WINDS WILL DEVELOP TONIGHT...BEFORE DYING BACK OFF SUNDAY NIGHT INTO MONDAY WITH THE APPROACH OF HIGHER PRESSURE. THESE LIGHTER WINDS CONTINUE INTO TUESDAY. && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY FROM 1 AM TO 7 PM EST SUNDAY FOR MIZ016>036-041-042. LH...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY FOR LHZ345>349. LM...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY FOR LMZ323-341-342-344>346. LS...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY FOR LSZ321-322. && $$ UPDATE...BA SYNOPSIS...AS SHORT TERM...SD LONG TERM...AS AVIATION...BA MARINE...SD
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
105 PM EST SAT DEC 21 2013 LATEST UPDATE... HYDRO .SYNOPSIS... ISSUED AT 1245 PM EST SAT DEC 21 2013 A STORM SYSTEM APPROACHING FROM THE SOUTHWEST WILL AFFECT THE AREA WITH A VARIETY OF WINTER WEATHER BEGINNING THIS EVENING. SOUTH CENTRAL LOWER MICHIGAN WILL LIKELY EXPERIENCE FREEZING RAIN AND ICE ACCUMULATION WHERE TEMPERATURES SHOULD HOVER AROUND FREEZING. FURTHER NORTH INTO CENTRAL LOWER MICHIGAN...THE PRECIPITATION TYPE WILL TRANSITION TO A WINTRY MIX AND EVENTUALLY TO A HEAVY WET SNOW. WINTRY PRECIPITATION WILL TAPER OFF SUNDAY AFTERNOON AND EVENING. MUCH COLDER AIR WILL FILTER IN BEHIND THE SYSTEM FOR AT LEAST THROUGH CHRISTMAS DAY. SNOW WILL DEVELOP AGAIN LATE SUNDAY NIGHT AND INTO MONDAY WITH THE POTENTIAL FOR SOME ACCUMULATIONS. THERE WILL BE ADDITIONAL CHANCES FOR SNOW THROUGH THE WORK WEEK. && .UPDATE... ISSUED AT 945 AM EST SAT DEC 21 2013 DENSE FOG IS BECOMING AN INCREASING CONCERN THIS MORNING MAINLY ALONG AND SOUTH OF AN EAST-WEST SURFACE BOUNDARY LOCATED JUST NORTH OF I-94. THERE ARE MANY REPORTS OF VISIBILITY AT OR BELOW 1/4 MILE ALONG AND SOUTH OF THIS BOUNDARY. HRRR GUIDANCE PUSHES THE BOUNDARY SOUTH OF THE FORECAST AREA BY THIS AFTERNOON WITH INCREASING WINDS FROM THE NORTHEAST...SO EXPECT DENSE FOG TO BE LESS OF A CONCERN BY AFTERNOON. WILL HIGHLIGHT THE ONGOING FOG CONCERN IN AN UPCOMING WSW UPDATE. RADAR SHOWS THAT PRECIPITATION HAS BEGUN TO OVERSPREAD THE AREA SOUTHEAST OF A MARSHALL TO MASON LINE. WE ARE A LITTLE CONCERNED ABOUT AIR TEMPERATURES STAYING SUFFICIENTLY COLD FOR ICE ACCUMULATION IN THE WARNED AREA. TEMPERATURES AND DEWPOINTS ARE VERY CLOSE TO FREEZING. A POSITIVE FOR FREEZING RAIN IS COLDER AND SLIGHTLY DRIER AIR UPSTREAM TO THE NORTHEAST. ALSO SEVERAL MESONET SITES IN THE AREA ARE REPORTED TEMPERATURES BELOW FREEZING. CURRENT EXPECTATIONS ARE THAT ICE ACCUMULATION ON SECONDARY ROADS AND EXPOSED ROAD SURFACES REMAIN A DEFINITE CONCERN. WILL BE CLOSELY MONITORING TEMPERATURE TRENDS OVER THE NEXT FEW HOURS. && .SHORT TERM...(TODAY THROUGH SUNDAY NIGHT) ISSUED AT 329 AM EST SAT DEC 21 2013 THE MAIN FOCUS OF THE SHORT TERM IS THE STORM SYSTEM EXPECTED TO IMPACT THE AREA BEGINNING TODAY AND LASTING THROUGH SUNDAY. WE HAVE TRANSITIONED THE HEADLINES FROM THE WATCH...TO AN ICE STORM WARNING ACROSS THE FAR SE CORNER OF THE CWFA. ADVISORIES HAVE BEEN ISSUED FOR THE REMAINDER OF THE CWFA FOR SNOW ACROSS THE NORTH AND A WINTRY MIX ACROSS THE MIDDLE SECTION OF THE CWFA. NO MAJOR CHANGES IN THE FCST HAVE BEEN MADE AS THE CONSENSUS OF THE MODELS IS GENERALLY CONSISTENT WITH THE PREVIOUS RUNS. WE WILL NEED TO DEAL WITH SOME FOG ISSUES ACROSS THE SOUTH THIS MORNING. THE GREATEST IMPACT OF THE INCOMING STORM SYSTEM LOOKS TO BE THE THREAT OF RELATIVELY SIGNIFICANT AMOUNTS OF FREEZING RAIN/ICING EXPECTED ROUGHLY SE OF I-69 LATER TODAY AND INTO THE EARLY OVERNIGHT HOURS TONIGHT. WE EXPECT RAIN AND OR FREEZING RAIN TO START PUSHING UP INTO THE SRN COUNTIES TOWARD THE AFTERNOON TODAY. AREAS ALONG AND SOUTH OF I-94 COULD START OUT BARELY ABOVE FREEZING AT THE ONSET OF PCPN. WE EXPECT ALL PCPN DOWN ACROSS THE SE CORNER TO TRANSITION TO FREEZING RAIN AS THE COLD AND SOMEWHAT DRIER NE FLOW WILL BRING TEMPS DOWN DUE TO ADVECTION AND EVAPORATIVE COOLING. QPF ACROSS THE SE COUNTIES LOOKS TO BE OVER AN INCH THROUGH THE EARLY OVERNIGHT HOURS AS THEY BARELY GET UNDER THE NRN PERIPHERY OF THE BEST MOISTURE AXIS WITH THIS SYSTEM. AN ABOVE FREEZING LAYER ALOFT IS MAINTAINED MOST OF THE TIME AS THE SFC TEMPS DROP TO AROUND OR JUST BELOW FREEZING. NOT ALL OF THIS QPF WILL GO INTO THE ICING EXPECTED DUE TO LATENT HEAT AND RUNOFF PROCESSES. HOWEVER WITH THAT MUCH QPF...EVEN A PORTION OF IT FREEZING WILL CREATE A GOOD COATING OF ICE...UP AROUND HALF AN INCH WILL BE LIKELY. THE TRANSITION IN P-TYPE WILL BE SOMEWHAT TRICKY ACROSS THE CENTRAL PORTION OF THE CWFA NW OF I-69 TO ROUGHLY M-20. HOWEVER WE EXPECT THAT FREEZING RAIN AND SLEET TO BE MORE PREVAILING WITH SOME SNOW POSSIBLE. A SLIGHT ABOVE FREEZING LAYER WILL BE PRESENT WITH THE LAYER THINNER AND COOLER AS YOU MOVE NW. QPF AMOUNTS WILL BE QUITE A BIT LESS AS THE MOISTURE AXIS REMAINS SE OF THIS AREA. IT WILL BE TOUGH TO GET HIGH IMPACT FREEZING RAIN AMOUNTS IN THIS AREA. HOWEVER ONE THING TO CONSIDER IS THE GLAZE IN PLACE ALREADY FROM THE THU NIGHT/FRI EVENT. THE PCPN IN BOTH OF THESE AREAS IS EXPECTED TO LIGHTEN UP SIGNIFICANTLY BETWEEN 06-12Z SUN AS THE DRY SLOT IS EXPECTED TO MOVE OVER THESE AREAS. SOME LIGHT PCPN WILL REMAIN...HOWEVER WE COULD SEE IT TRANSITION TO FZDZ AS THE DGZ BECOMES UNSATURATED. BY THE TIME PCPN REACHES THE NRN PORTION OF THE CWFA...THE COLUMN SHOULD BE MAINLY COLD ENOUGH TO SUPPORT MAINLY SNOW. THE SNOW SHOULD START OUT LIGHT...AND PICK UP LATE TONIGHT/SUN MORNING AS THE BEST DEFORMATION SLIDES ACROSS THE NRN COUNTIES AND NW OF THE CWFA. SNOW AMOUNTS ARE GENERALLY EXPECTED TO REMAIN IN THE ADVISORY CATEGORY AS THE UPPER LOW EJECTING WILL HAVE OPENED UP BY THE TIME IT REACHES HERE AND THE FGEN IN THE DEFORMATION WILL NOT BE AS STRONG AS TO OUR SW. ONE THING GOING FOR BETTER SNOW AMOUNTS HERE IS THE FACT THAT THE DGZ IS EXPECTED TO REMAIN SATURATED AS THE DRY SLOT REMAINS SE OF THIS AREA. THE CAVEAT TO ALL OF THIS IS IF THE OUTLIER NAM IS CORRECT...ALL OF THIS WOULD BE SHIFTING TO THE NW A LITTLE. WE BELIEVE AT THIS TIME THAT WE HAVE A GOOD CONSENSUS OF THE TRACK OF THE SYSTEM WITH GOOD RUN TO RUN CONSISTENCY FROM MOST OF THE GLOBAL MODELS AND IT SHOULD BE WELL SAMPLED BY NOW WITH IT BEING WELL WITHIN THE RAOB NETWORK. WE WILL SEE A TRANSITION TO SOME LAKE EFFECT SNOW SHOWERS ON SUN NIGHT AS COLDER AIR COMES IN BEHIND THE SYSTEM. THE FLOW SHOULD BE NNW WHICH WOULD FAVOR THE IMMEDIATE LAKESHORE FOR BEST SNOW SHOWER CHANCES. THERE IS SOME DECENT MOISTURE UP THROUGH 15K FEET AND OVER-LAKE INSTABILITY IS SUFFICIENT. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 329 AM EST SAT DEC 21 2013 THE UPCOMING CHRISTMAS WEEK WILL BE MORE LIKE WHAT WE HAVE SEEN FOR MUCH OF DECEMBER: COLDER THAN NORMAL WITH FREQUENT CHANCES FOR SNOW SHOWERS. THE NORTHERN BRANCH OF THE JET AND ARCTIC AIR WILL DOMINATE THROUGHOUT THE WEEK... WITH SEVERAL SHORTWAVES AND SFC TROUGHS/FRONTS SWINGING THROUGH THE GRTLKS RGN. TEMPERATURES ARE EXPECTED BE BELOW FREEZING ALL WEEK... AND THE COLDEST DAY OF THE WEEK WILL BE TUESDAY WHEN HIGHS SHOULD STRUGGLE TO REACH 20 BEHIND THE FIRST NRN STREAM WAVE. GFS/ECMWF ARE IN GOOD AGREEMENT SHOWING A POTENT SHORTWAVE IMPACTING THE AREA MONDAY AFTERNOON AND NIGHT. SNOW SHOWERS ARE LIKELY AND LAKE ENHANCEMENT WILL BE IN PLAY AS THIS FEATURE COMES THROUGH. HOWEVER CONFIDENCE IN WIND DIRECTION IS LOW SINCE MODELS INDICATE A WEST TO EAST ORIENTED SFC TROUGH SETTING UP SOMEWHERE ACROSS LWR MI AND ARE NOT IN GREAT AGREEMENT WITH IT/S LOCATION AND RESULTANT WINDS. NEVERTHELESS THE TROUGH SHOULD RESULT IN LOCALLY ENHANCED CONVERGENCE WITH A LARGE PORTION OF THE CWFA SEEING SNOW SHOWERS AND AT LEAST SOME LIGHT ACCUMULATIONS. IF A WESTERLY FLOW DEVELOPS THEN AREAS ALONG AND WEST OF HWY 131 COULD SEE SEVERAL INCHES BUT AGAIN WIND DIRECTION IS VERY QUESTIONABLE AT THIS TIME. A BRIEF PERIOD OF SHORTWAVE RIDGING MOVES ACROSS FOR TUESDAY AFTERNOON AND EVENING... THEN SOME WAA/ISENTROPIC LIFT LIGHT SNOW POSSIBLE ON CHRISTMAS DAY AHEAD OF THE NEXT APPROACHING SHORTWAVE. THE ECMWF HAS A MUCH STRONGER SHORTWAVE THAN THE GFS FOR THE 26TH AND WOULD SUGGEST A DECENT ROUND OF ACCUMULATING LAKE ENHANCED SNOW SHOWERS FOR THURSDAY AND THURSDAY NIGHT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1258 PM EST SAT DEC 21 2013 WIDESPREAD LIFR ACROSS THE REGION THIS AFTERNOON. NOT EXPECTING MUCH OVERALL CHANGE OVER THE NEXT 24 HOURS. THE DIFFICULT ASPECT OF THE FORECAST IS DETERMINING WHEN PCPN WILL OCCUR AT THE TAF SITES AND WHAT TYPE OF PCPN WILL FALL. RATHER THAN A LONG DURATION OF PCPN...IT APPEARS WE WILL SEE A PERIOD OF PCPN THIS EVENING...THEN AS A DRY SLOT COMES IN...THE PCPN MAY END FOR A BIT OVERNIGHT...THEN ANOTHER PERIOD OF PCPN SHOULD OCCUR FOR MUCH OF SUN MORNING. AS FOR PCPN TYPE...THE RAIN TO WINTRY MIX LINE RAN FROM NEAR BIV TO TEW AT 17Z. THIS APPEARS TO CHANGE LITTLE INTO TONIGHT...WHICH MEANS THE I-94 TAF SITE SHOULD REMAIN RIGHT ON THE EDGE OF THE ICY PCPN. HAVE GONE MORE OPTIMISTIC WITH LIQUID PCPN AT THE I-94 TAF SITES...BUT THIS IS A VERY CLOSE CALL...AND WE WILL CONTINUE TO MONITOR. MEANWHILE THE I-96 TAF SITES CAN CONTINUE TO EXPECT PERIODS OF FREEZING RAIN WHICH SHOULD BEGIN TO SWITCH TO SNOW AND/OR SLEET MID/LATE SUNDAY MORNING. && .MARINE... ISSUED AT 534 PM EST FRI DEC 20 2013 NORTHEAST FLOW WILL CONTINUE INTO SATURDAY NIGHT. THIS OFFSHORE FLOW WILL HELP KEEP WAVES LOWER. HOWEVER AS WINDS PIVOT TO THE NORTH NORTHWEST LATE SATURDAY NIGHT/EARLY SUNDAY MORNING WAVES WILL BUILD AND WE WILL LIKELY NEED A SMALL CRAFT ADVISORY BY THEN. && .HYDROLOGY... ISSUED AT 103 PM EST SAT DEC 21 2013 THE HEADWATERS OF THE GRAND AND ST. JOSEPH RIVER BASINS ARE EXPECTED TO RECEIVE AROUND 0.75 INCHES OR LESS WITH THIS EVENT. BEST CHANCE FOR FLOODING REMAINS TO THE SOUTH IN NORTHERN INDIANA AND NORTHWEST OHIO. A SHARP RISE BELOW FLOOD STAGE OF THE GRAND RIVER AT JACKSON IS EXPECTED...BUT THIS RISE WILL BE BRIEF AND SHOULD FALL QUICKLY. STORM EVOLUTION WILL BE MONITORED CLOSELY FOR HEAVIER PRECIP AMOUNTS OVER THE GRAND HEADWATERS. TEMPERATURES ARE HOVERING NEAR FREEZING TODAY. SNOW MELT COULD CONTRIBUTE TO RISES AS WELL. ICE BREAKUP AND MOVEMENT COULD CAUSE RIVER RISES ON SUNDAY WITH TEMPS REACHING THE UPPER 30S IN SOUTH CENTRAL LOWER MICHIGAN. ARCTIC AIR STREAMS BACK IN ON SUNDAY NIGHT. MONDAY NIGHT AND TUESDAY NIGHT ARE EXPECTED TO BE VERY COLD...WITH LOWS IN THE SINGLE DIGITS POSSIBLE. ICE DEVELOPMENT ON RIVERS IS EXPECTED...SO THE RISK FOR ICE JAM FLOODING INCREASES. TEMPS WILL STAY BELOW FREEZING THROUGH ALL OF NEXT WEEK. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR MIZ051-052- 056>059-064-065-071-072. ICE STORM WARNING UNTIL 7 AM EST SUNDAY FOR MIZ066-067-073-074. WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY FOR MIZ037>040-043>046-050. LM...NONE. && $$ UPDATE...TJT SYNOPSIS...JAM SHORT TERM...NJJ LONG TERM...MEADE AVIATION...JK HYDROLOGY...EBW MARINE...JK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1254 PM EST SAT DEC 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 457 AM EST SAT DEC 21 2013 SW FLOW ALOFT BTWN UPPER LOW OVER HUDSON BAY AND STRONG SOUTHERN STREAM DISTURBANCE OVER NEW MEXICO. THROUGH TONIGHT...MAIN ISSUES ARE TIED TO LAKE EFFECT. SOUTHERN STREAM WAVE LIFTS TOWARD UPPER GREAT LAKES LATER TONIGHT...THOUGH IT APPEARS MAJORITY OF WIDESPREAD SNOW WITH THE DEVELOPING LOW PRESSURE SYSTEM WILL REMAIN JUST SOUTH OF CWA UNTIL DAYBREAK ON SUNDAY. EMBEDDED SHORTWAVES/PV ANOMALIES IN FLOW ALOFT HELPING TO SUSTAIN LGT SNOW/FLURRIES OVER CWA EARLY THIS MORNING. ALSO A BAND OF ENHANCED LK EFFECT MAINLY OVER SCNTRL AND SOUTHEAST PORTIONS OF LK SUPERIOR. RAP...WHICH DOES HAVE DECENT HANDLE ON BACK EDGE OF LGT SNOW CURRENTLY...INDICATES MID-LEVEL MOISTURE/UVM EXITS EAST HALF OF CWA THROUGH AROUND DAYBREAK THIS MORNING SO WOULD EXPECT LGT SNOW TO END FOR A TIME. AT THE LEAST THE CLOUDS WILL CONTINUE TO HOLD UP TEMPS THIS MORNING MAINLY IN THE TEENS. MILD FOR SURE COMPARED TO THE RECENT CHILL UPR LAKES HAS EXPERIENCED. CURRENTLY THERE IS A SFC TROUGH ACROSS THE AREA EXTENDING TO THE NW OF SFC LOW NEAR DETROIT. EXPECT TROUGHING TO PERSIST THROUGH MUCH OF THE DAY WHILE GRADUALLY GETTING PUSHED TO THE SOUTH AND EAST BY THIS AFTN AS HIGH PRESSURE OVR SASKATCHEWAN AND MANITOBA TRIES TO RIDGE ACROSS LK SUPERIOR REGION. THE MAIN IMPACT THIS HAS IS ON WIND FIELDS AND ASSOCIATED LAKE EFFECT AS THERE IS ENOUGH INSTABILITY WITH INVERSIONS UP TO 5-7KFT AND TEMPS AT INVERSION TOP AROUND -13C WHILE WATER TEMPS ARE AROUND +3C. SOUNDINGS AT P59/CMX AND STDM4 INDICATE DECENT SUBSIDENCE ABOVE MOIST LAKE EFFECT LAYER AND ALSO NOT AS MUCH LIFT WITHIN THE DGZ. IF CONVERGENCE CAN PERSIST OVER THE KEWEENAW TODAY...THEN THERE IS AN OPPORTUNITY FOR ADVY LEVEL SNOW AMOUNTS. CONFIDENCE IS LOW ON THIS POTENTIAL AND EVEN LOWER ON EXACTLY WHERE THAT WOULD OCCUR. FOLLOWED GEM-REGIONAL THROUGH TODAY FOR WINDS ALONG WITH NAM AND LOCAL-WRF MODEL BASED ON RAP BOUNDARY CONDITIONS. THIS BLEND ESSENTIALLY HANGS UP MAIN CONVERGENCE AREA OVER NORTHERN KEWEENAW THEN EVENTUALLY DRAWS IT SOUTH ACROSS THE PENINSULA THIS AFTN AS THE HIGH BUILDS TOWARD LK SUPERIOR. SINCE INSTABILITY IS NOT EXTREME OR OVER THE TOP BY ANY MEANS...FCST SNOW AMOUNTS FROM 2-4 INCHES...GREATEST NEAR MOHAWK/EAGLE RIVER/COPPER HARBOR. DESPITE MODELS NOT SHOWING MUCH OCCURRING FOR OTHER AREAS WHERE FLOW IS ONSHORE NEAR LK SUPERIOR...WENT WITH PERSISTENCE AND KEPT MENTION OF SNOW OVER FAR WESTERN UPR MICHIGAN AND ALSO IN NCNTRL UPR MICHIGAN. ANY AMOUNTS FOR THESE AREAS TODAY WILL JUST A DUSTING OF LESS THAN 1 INCH. MINOR ISSUE FOR TODAY IS SKY COVER AND TEMPS. MODELS STRUGGLING WITH EVENTUAL EVOLUTION OF LOW MVFR CLOUDS FM LK SUPERIOR BACK INTO CNTRL MINNESOTA. NAM/RAP/GEM-REGIONAL SHOW THESE CLOUDS TO START BUT SEEM TOO QUICK TO GET RID OF THEM OVER ALL BUT WESTERN CWA BY LATER MORNING. WE WILL SEE ON THIS. IF MORE SUN OCCURS...MAX TEMPS MAY PUSH WELL INTO THE MID-UPR 20S CNTRL. BASED ON CURRENT SATELLITE/OBS TRENDS AND WITH SUN ANGLE ABOUT AS LOW AS IT GETS...WILL KEEP SKIES MOSTLY CLOUDY FOR TODAY. LATER TODAY WILL BE A MOOT POINT AS INCREASING NE WINDS SHOULD RESULT IN EXPANSION OF CLOUDS OFF LK SUPERIOR. SOUTHERN STREAM WAVE/LOW PRESSURE SYSTEM AFFECTS WILL BE KNOCKING ON THE DOOR OF UPR MICHIGAN SO TO SPEAK LATER TONIGHT. NAM/GFS/ECMWF LOOKED SIMILAR WITH PLACEMENT OF H5 TROUGH/PRIMARY PV ANAMOLY/H85 AND SFC LOWS. GEM WAS FARTHER NORTH WITH H85 LOW. SEEMED THAT ECMWF WAS A NICE MIDDLE GROUND BTWN FARTHER SOUTH NAM/GFS WITH ADVANCING WIDESPREAD SNOW AND MORE AGRESSIVE GEM. BROUGHT LIKELY POPS FOR SYNOPTIC SNOW INTO FAR SCNTRL BY 09Z SUNDAY. OTHER IMPACT WILL BE INCREASING FAVORABLE LAKE EFFECT OVER FAR WEST/KEWEENAW AND NCNTRL CWA. NOT EXPECTING A LOT OF SNOW AS ANY LARGE SCALE FORCING IS MINIMAL THROUGH 12Z...BUT THERE IS ENOUGH EVIDENCE IN FCST SOUNDINGS THAT LAKE EFFECT WILL BE DEVELOPED ENOUGH TO RESULT IN LIKELY POPS WITH MINOR SNOW AMOUNTS. SETUP BECOMES MUCH MORE FAVORABLE FOR SIGNIFICANT LAKE ENHANCEMENT FOR SUNDAY AND BEYOND. BTWN THE LAKE EFFECT MOISTURE/SNOW AND MID-HIGH CLOUDS ARRIVING FROM THE SOUTH...EXPECT TEMPS TONIGHT TO STAY IN THE TEENS AGAIN. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 457 AM EST SAT DEC 21 2013 HAVE OPTED TO ISSUE A WINTER STORM WATCH FOR THE TERRAIN/LAKE ENHANCED AREAS OF MARQUETTE/BARAGA COUNTIES AS WELL AS GOGEBIC AND ONTONAGON COUNTIES FOR SUNDAY AND MONDAY. LONG DURATION LAKE ENHANCED/LAKE EFFECT SNOW EPISODE LOOKING MORE POSSIBLE NOW AS THE MODELS ARE STARTING TO COME INTO BETTER AGREEMENT INTO A MAIN LOW TRACK THROUGH SOUTHERN MI ON SUNDAY. HOWEVER...THE COMPLEX INTERACTION BETWEEN THE SOUTHERN STREAM ENERGY MOVING THROUGH THE LOWER LAKES AND THE NORTHERN STREAM TROUGH MOVING INTO THE UPPER MIDWEST MAKES THIS FORECAST CONFIDENCE STILL SOMEWHAT BELOW AVERAGE. ONTO THE DETAILS...AS SAID ABOVE THE NWP SUITE HAVE COME INTO BETTER AGREEMENT WITH THE MAIN LOW MOVING THROUGH SOUTHERN LOWER MICHIGAN WITH THE SOUTHERN STREAM IMPULSE MOVING OUT OF THE PLAINS. EXPECT SYNOPTIC MOISTURE AND LIFT TO GLANCE BY THE SOUTHEAST FORECAST AREA SUNDAY MORNING INTO EARLY AFTERNOON AS THE COMMA HEAD/DEFORMATION ZONE PCPN MOVES THROUGH. THIS TRACK WILL ALLOW FOR 1000-850MB WINDS TO TURN NE AND SHOULD ALLOW FOR LAKE ENHANCEMENT TO ALSO DEVELOP IN MARQUETTE/BARAGA COUNTIES AS WELL AS THE FAR WEST NEAR IRONWOOD. CONSENSUS QPF FROM THE NWP SUGGEST ABOUT 0.20-0.30 INCH OF QPF NEAR LAKE MICHIGAN AND FAR EAST ON SUNDAY...WITH MUCH LESSER AMOUNTS WELL INLAND AWAY FROM FROM LAKE SUPERIOR. THIS ALSO SEEMS REASONABLE GIVEN THAT 700MB MIXING RATIOS REMAIN AROUND 2 G/KG THROUGH EARLY AFTERNOON. GIVEN THAT SOME OF THE LIFT WILL BE IN THE DGZ AREA ACROSS THE SOUTH DURING THE DAY...WE SHOULD SEE SNOW RATIOS ACROSS THE FAR SOUTHEAST AROUND 15-17:1 DURING THE DAY WHICH WOULD EQUATE TO 3-5 INCHES OF SNOW BY EVENING. MOST LIKELY AN ADVISORY WILL BE NEEDED IN THIS AREA ON SUNDAY...BUT WILL HOLD OFF SINCE THIS WILL BE GENERALLY A 3RD PERIOD ADVY. AS FOR AREAS CLOSER TO LAKE SUPERIOR...ALL OF THE NWP GUIDANCE SHOW PBL WINDS STAYING NELY THROUGH THE DAY WHICH SHOULD ALLOW FOR TERRAIN ENHANCED SNOW TO COMMENCE IN THE NE FLOW FAVORED AREAS DESPITE THE RELATIVELY WEAK SYNOPTIC LIFT. WITH THE BEST LIFT BEING CONFINED TO GENERALLY BELOW THE DGZ...EXPECT SNOW RATIOS BE BE FAIRLY LOW WITH ONLY AROUND 13:1. WILL GENERALLY GO WITH 4 OR 5 INCHES AT MOST IN THESE AREAS...BUT GIVEN THE STRONG AND DEEP NE FLOW...WOULD NOT BE SHOCKED IF QPF AND THUS SNOWFALL IS MORE ON SUNDAY. THEN ON SUNDAY NIGHT...DIFFERENCE START TO DEVELOP WITH THE MODELS REGARDING THE EVOLUTION OF THE NORTHERN STREAM UPPER TROUGH. THE NAM IS CERTAINLY THE MOST AGGRESSIVE IN CLOSING OFF THE LOW AND SETTLING OVER THE UPPER GREAT LAKES...WHICH ALLOW FOR A STRONG INVERTED TROUGH TO HANG BACK ACROSS THE CENTRAL GREAT LAKES THROUGH MONDAY. MEANWHILE...THE GFS GENERALLY KEEPS THE UPPER TROUGH OPEN AND MOVES IN THROUGH THE AREA BY MONDAY AFTERNOON. THE LATEST 00Z ECMWF IS INTERESTING AS IT ALSO ATTEMPT TO CLOSE OFF THE LOW SUN NIGHT BUT IS NOT NEARLY AS DEEP AS THE NAM FORECASTS. NONETHELESS...THE ECMWF ALSO SUGGESTS THAT THERE WILL BE SOME TYPE OF INVERTED TROUGH EXTENDING BACK INTO THE AREA THROUGH MONDAY AND OUR LOCALLY PRODUCE ARW-WRF USING THE GFS AS BOUNDARY CONDITIONS ALSO SUGGEST THAT THERE WILL BE A INVERTED TROUGH HANGING BACK THROUGH MONDAY. AS SUCH...DO NOT THINK THE PBL WINDS WILL SHIFT TO N-NW AS FAST AS THE GFS AND ECMWF SUGGEST. IN FACT...THE CURRENT THINKING IS THAT THE WINDS WILL STAY NORTHERLY OR PERHAPS A LITTLE EAST OF NORTH THROUGH MONDAY WITH THIS TROUGH STAYING SOUTH OF THE AREA. WITH ALL OF THIS SAID...THE EXPECTATION IS THAT THE SNOW WILL TRANSITION TO MORE LAKE ENHANCED VARIETY AND PERSIST RIGHT THROUGH MONDAY BEFORE THE UPPER TROUGH SWINGS THROUGH AND ALLOWS THE WIND TO GRADUALLY SHIFT TO THE N-NW BY MON EVENING. AS SUCH...EXPECT MODERATE TO LOCALLY HEAVY SNOW TO CONTINUE IN MQT/BARAGA COUNTIES AS WELL AS GOGEBIC COUNTY THROUGH THE NIGHT SUNDAY INTO MONDAY. THE BEST LIFT RAPIDLY BECOMING ENTRENCHED IN THE DGZ SUNDAY EVENING AS THE UPPER TEMPS DROP...EXPECT THE SNOW TO BECOME MUCH MORE FLUFFY BUT ALSO ACCUMULATE MUCH FASTER WITH RATIOS CLOSE TO 25:1 BY MON MORNING. SOME AREAS IN THE WATCH AREA COULD SEE ANOTHER 8-12 INCHES OF SNOW SUN NIGHT INTO MONDAY. INTERESTINGLY...THERE ARE SEVERAL VERY GOOD CIPS ANALOG EVENTS FOR THIS SYSTEM. THEY ALL GENERALLY SHOW THE WATCH AREA SEEING SIGNIFICANT 72 HOUR SNOWFALL. NOT SURE IF WE WILL SEE ANY LONGER PERIOD OF HEAVY SNOWFALL...RATHER I AM THINKING THAT IT WILL BE GENERALLY A PERSISTENT SNOWFALL FOR 24-36 HOURS WHICH WILL ALLOW WARNING CRITERIA TO BE REACHED. EVEN MORE INTERESTING...DESPITE THE FACT THAT GOGEBIC COUNTY WILL BE FURTHEST REMOVED FROM THE SYSTEM...THE CURRENT NWP AND ALSO THE CIPS GUIDANCE SUGGEST THAT THIS AREA COULD SEE THE MOST SNOWFALL OUT OF THIS EVENT. WE WILL SEE... ANY REMAINING LES SHOULD END RAPIDLY MON NIGHT/TUE MORNING AS THE HIGH PRES RIDGE BUILDS ACROSS THE FORECAST AREA. STILL LOOKS QUITE COLD TUE MORNING ACROSS THE WEST WITH LIGHT WINDS/CLEAR SKIES. TEMPS 10-20 BELOW NOT OUT OF THE QUESTION IN THE NORMALLY COLDER SPOTS. THE ECMWF AND GEM ARE IN GOOD AGREEMENT IN LIGHT OVERRUNNING/WARM ADVECTION SNOW CHRISTMAS EVE NIGHT INTO CHRISTMAS DAY ACROSS THE ENTIRE FORECAST AREA. SOME HINTS THAT THERE MIGHT BE SOME LAKE ENHANCEMENT OFF OF LAKE MICHIGAN TUESDAY NIGHT AND HAVE OPTED TO CONTINUE LIKELY POPS ACROSS THE EASTERN PART OF THE FORECAST AREA TUE NIGHT INTO CHRISTMAS DAY. SOME DIFFERENCES EMERGE THU INTO FRIDAY REGARDING THE EVOLUTION AND THE TROUGH WITH THE ECMWF BEING DEEPER AND FURTHER SOUTH COMPARED TO THE GFS. REGARDLESS...SENSIBLE WEATHER SHOULD GENERALLY THE SAME WITH EITHER MODEL WITH LES IN THE NW FAVORED SNOWBELTS CHRISTMAS NIGHT INTO THU NIGHT BEFORE DIMINISHING ON FRIDAY AS HIGH PRES BUILDS OVERHEAD. TEMPS STILL LOOK BELOW NORMAL THROUGH THE EXTENDED WITH 850MB TEMPS -20 TO -25C WED NIGHT/THU WARMING TO -15 TO -20C BY FRIDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1243 PM EST SAT DEC 21 2013 KIWD...LIGHT WINDS BECOMING ONSHORE NE DIRECTION SHOULD ENSURE MVFR CIGS AND LIGHT LAKE SNOW SHOWERS ACROSS THE TAF SITES BY LATE THIS AFTERNOON. IFR VSBY IN SNOW AND BLSN IS EXPECTED TO DEVELOP AT WRN TAF SITES LATE TONIGHT ESPECIALLY AS NE WINDS AND INSTABILITY INCREASES OVER WRN LAKE SUPERIOR. WINDS BECOMING MORE EASTERLY WILL SCATTER OUT THE LOW CLOUDS AT SAW LATE TONIGHT. WIDESPREAD SNOW IS EXPECTED TO IMPACT ALL TERMINALS ON SUNDAY AS A LOW PRESSURE SYSTEM SLIDES ACROSS THE CENTRAL GREAT LAKES REGION. HEAVIEST SNOW WILL OCCUR AT IWD WITH UPSLOPE NORTHEAST WINDS PROVIDING ADDITIONAL SUPPORT FOR SNOW OFF LK SUPERIOR. AS A RESULT...VSBYS AT KIWD COULD LOWER TO LIFR BY LATE SUNDAY MORNING. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 457 AM EST SAT DEC 21 2013 LIGHT WINDS TODAY WITH TROUGH OVER THE LAKE THEN AS THE TROUGH SINKS SOUTH TONIGHT...EXPECT STRONG AND GUSTY NORTHEAST WINDS TO 30 KTS OVER MUCH OF LAKE SUPERIOR INTO SUNDAY...FURTHER STRENGTHENED BY LOW PRESSURE LIFTING ACROSS LOWER MICHIGAN. COULD BE GALE GUSTS OVER THE WEST WITH CHANNELING BETWEEN MINNESOTA SHORELINE AND KEWEENAW PENINSULA. DURING THIS PERIOD OF STRONGER WINDS THERE WILL BE FREEZING SPRAY. EXPECT THE LOW TO LINGER A SURFACE TROUGH OVER THE UPPER GREAT LAKES THROUGH MONDAY AND KEEP WINDS UP TO 25 KTS. HIGH PRESSURE WILL CROSS THE UPPER GREAT LAKES ON MONDAY NIGHT...WHILE A LOW PRESSURE SYSTEM BEGINS TO TAKE SHAPE IN THE CANADIAN PRAIRIES. THIS LOW WILL LEAD TO INCREASING SOUTHERLY WINDS ACROSS LAKE SUPERIOR ON TUESDAY. WHEN THE LOW MOVES THROUGH THE REGION ON WEDNESDAY...WINDS WILL BECOME WESTERLY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER STORM WATCH FROM SUNDAY MORNING THROUGH MONDAY EVENING FOR MIZ002-004-005-009. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...MRD AVIATION...VOSS MARINE...JLA
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1028 AM EST SAT DEC 21 2013 .SYNOPSIS... ISSUED AT 457 AM EST SAT DEC 21 2013 QUIET WEATHER IS EXPECTED DURING THE DAY TODAY BEFORE ANOTHER STORM SYSTEM AFFECTS THE REGION TONIGHT INTO SUNDAY. THIS EVOLVING SYSTEM WILL LIFT INTO THE NORTHERN OHIO VALLEY SATURDAY NIGHT...BRINGING LIGHT TO MODERATE AMOUNTS OF SNOW TO THE REGION. COLD AIR WILL FILTER BACK INTO THE GREAT LAKES MONDAY AND TUESDAY...GENERATING SOME LAKE EFFECT SNOW...ACROSS PARTS OF NORTHERN MICHIGAN TO BEGIN THE UPCOMING WORK WEEK. A COUPLE OF ALBERTA CLIPPERS WILL THEN LIKELY BRINGING SOME LIGHT SNOW FOR CHRISTMAS DAY AND A CHANCE FOR LIGHT SNOW ON THURSDAY. && .UPDATE... ISSUED AT 1028 AM EST SAT DEC 21 2013 NO MAJOR CHANGES TO THE FORECAST AT THIS HOUR...AND AN OVERALL QUIET...ALBEIT CLOUDY DAY ON TAP FOR THE NORTH WOODS. 12Z APX REVEALING A FAIRLY DEEP SATURATED LOW LAYER UP TO NEARLY 750 MB...ALTHOUGH THE TEMP/DEWPOINT SPREAD DOES OPEN A BIT IN LAYERS. NONETHELESS...HAVE HAVE A FEW REPORTS OF -FZDZ AROUND THE TVC AREA AND OBS AROUND THE GRAND TRAVERSE BAY AREA DOES HINT AT PATCHY FZDZ VIA REDUCED VSBYS AND LOW CIGS. EVEN GLR REPORTING LOW VSBY AND FZFG. SO...HAVE ADDED PATCHY -FZDZ TO THE FORECAST THROUGH THE MORNING AND EVEN ISSUED AN SPS TO COVER SOME POTENTIAL SLICK SPOTS/BLACK ICE THIS MORNING. RUC FORECAST SOUNDINGS SHOW ONGOING LOW LEVEL DRYING/OPENING THE SOUNDINGS JUST A BIT THROUGH THE AFTERNOON...SUGGESTING -FZDZ WILL END. WILL SEE. OTHERWISE...JUST INGESTING OBSERVATIONAL TRENDS AND INCOMING 12Z GUIDANCE TO SEE WHAT...IF ANY ADJUSTMENTS MAY BE NEEDED TO THE UPCOMING EVENT LATER TONIGHT THROUGH SUNDAY. NO BIG SURPRISES SO FAR. UPDATE ISSUED AT 628 AM EST SAT DEC 21 2013 UPDATED SKY GRIDS. WINDS ARE TURNING LIGHT OUT OF THE NORTH WITH LITTLE TO NO SPEEDS REMAINING 5 KTS OR LESS. SLOWED ANY SORT OF GOOD LOW LEVEL DRYING AND AM KEEPING LOW CLOUDS AROUND THROUGH A GOOD PORTION OF THE DAY...PLUS A PLETHORA OF MID AND HIGH LEVEL CLOUDS REMAINS OVER MUCH OF THE REGION AND DO NOT SEE MUCH HAPPENING WITH THAT TODAY. THUS...CLOUDY FOR MOST OF THE DAY...THIS IS ESPECIALLY TRUE ACROSS THE SE CWA WHERE LOW LEVEL MOISTURE WILL BE RICH/THICK ENOUGH FOR CLOUDS. NO PRECIPITATION EXPECTED FOR THE DAY. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 457 AM EST SAT DEC 21 2013 CURRENTLY...SPLIT FLOW IN THE UPPER LEVELS WITH A NRN STREAM JET STREAK OVERHEAD...AND A SRN STREAM JET STREAK LIFTING INTO OK WHICH IS EJECTED FROM A CUT OFF LOW OVER FAR WEST TX. IN THE NRN STREAM...WE HAVE ONE WEAK AND SHEARED OUT VORT MAX RUNNING INTO EASTERN LAKE SUPERIOR...WHICH HAS CONTINUED TO PRODUCE LIGHT SNOW/FLURRY RETURNS ON MQT RADAR WHICH WERE WORKING UP THROUGH WESTERN SECTIONS OF CHIP/MACK COUNTIES OF EASTERN UPPER. H8 LLJ FORCING IS COMPLETELY DONE AS WIND DIRECTIONS HAVE VEERED WEST...AND ACTUALLY DRYING WAS UNDERWAY FROM NORTH TO SOUTH. THIS ALSO HELPING TO KEEP ANY LIGHT SNOW AT BAY ACROSS EASTERN UPPER. PECULIAR EARLIER WEAK RADAR RETURNS EMANATING FROM ANTRIM INTO CRAWFORD COUNTY HAS BEEN A VERY FINE LIGHT SNOW...AND THIS WAS ALSO ERODING...LIKELY DUE TO THE NOW H8 DRYING. TOTAL MOISTURE IN THE COLUMN IS DRYING...AND WILL NOW BE SLOWLY ERODING ANY CHANCE OF PRECIP AND PATCHY FREEZING DRIZZLE...THE LATTER OF WHICH SEEMS TO BE ISOLATED AT BEST...WITH ONLY CADILLAC OBSERVATION SUGGESTING THE POSSIBILITY OF FREEZING DRIZZLE...AND ACTUALLY BELIEVE THAT IS MORE OF A LOWERING CEILING/FREEZING FOG TYPE THING. DO NOT BELIEVE THAT THIS IS ANY SERIOUS IMPACT. TODAY AND TONIGHT...WEAK/SHEARED OUT VORT MAX WILL EXIT EAST OVER THE NEXT COUPLE OF HOURS WITH H8 DRYING CONTINUING TO SLIDE SOUTH...ENDING ALL LIGHT SNOW IN EASTERN UPPER. WINDS DO VEER MORE NORTHERLY INTO THE DAYLIGHT HOURS...AND LOW LEVEL TEMPS RESULT IN DELTA T`S SUFFICIENT ENOUGH FOR MAYBE A FEW FLURRIES ACROSS FAR NE LOWER. OUTSIDE OF THAT...A QUIET PERIOD OF WEATHER FOR THE DAY...WITH DEEP SW FLOW ALOFT...ABOVE THE SHALLOW COLDER AIR. THIS WILL CONTINUE TO BRING IN MIDDLE AND UPPER LEVEL CLOUDS. DO NOT SEE THE NORTHERLY FLOW BEING STRONG ENOUGH TO SCOUR OUT THE LOW LEVEL CLOUDS ACROSS THE SE PART OF THE CWA. THIS WILL RESULT IN A RETURN A DEEPLY SATURATED ATMOSPHERE IN THE AFTERNOON. WE WILL SEE SOME WEAK ENERGY EJECTED FROM THE SRN STREAM CUT OFF WORKING IN OVER THE FAR SE CWA LATE IN THE AFTERNOON FOR THE FIRST CHANCES FOR SEEING SOME LIGHT SNOW FALL. STRONGER ENERGY/MODERATE DEEP LAYER -DIVQ ARRIVES OVERNIGHT...AS THE ATMOSPHERE DEEPENS IN MOISTURE. THIS WILL MAINLY BE ACROSS NRN LOWER. THE DEEP MOISTURE IS BROUGHT IN BY A WIDE OPEN GULF (CURRENTLY STREAMING DEEP LOW LEVEL MOISTURE INTO THE OHIO RIVER VALLEY) ARRIVES VIA STRONG LOW LEVEL JET. AS THE SRN STREAM CUT OFF OPENS UP AND LIFTS INTO ILLINOIS LATE TONIGHT/DAYBREAK TOMORROW...THE SFC LOW DEEPENS SOME...AND WINDS BACK...ALLOWING THE BEST LOW LEVEL MOISTURE TURN GET LIFTED FURTHER NORTH INTO OUR NECK OF THE WOODS. AT THE SAME TIME...STRONG DEEP LAYER -DIVQ IS SETTLED IN ON US...AND SNOWS WILL PICK UP IN INTENSITY. CAN SEE AROUND A COUPLE OF INCHES BY DAYBREAK ACROSS THE SE CWA...LESSENED NEAREST THE SAG BAY BY LOW LIQUID-SNOW RATIOS AND THE POSSIBILITY (IF WARMER NAM IS RIGHT) OF A MIX WITH SLEET. FOR A DISCUSSION ON THE WATCH SITUATION...SEE BELOW. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 457 AM EST SAT DEC 21 2013 AN ACTIVE WEATHER PATTERN ALONG WITH COLD TEMPERATURES CONTINUE THROUGH THE FORECAST PERIOD WITH A MEAN TROUGH REMAINING IN PLACE ACROSS CENTRAL CANADA INTO THE GREAT LAKES REGION. IN ADDITION...UPPER LEVEL DISTURBANCES MOVING THROUGH THE FLOW ALOFT WILL BRING NUMEROUS CHANCES FOR SNOW SHOWERS...ENHANCED FROM TIME TO TIME BY THE BIG LAKES. MEANWHILE...THE WELL ADVERTISED SOUTHERN JET STREAM SYSTEM COULD STILL POTENTIALLY BRING WHAT LOOKS LIKE A MODERATE AMOUNT OF SNOW TO REGION LATER SATURDAY NIGHT INTO SUNDAY. THE MAIN LONG TERM FORECAST CONCERNS REVOLVE AROUND SNOW AMOUNTS FOR SATURDAY NIGHT INTO SUNDAY THEN THE USUAL SUSPECTS...POPS AND TEMPERATURES FOR THE REMAINDER OF THE FORECAST. SUNDAY...SOUTHERN BRANCH ENERGY MOVES NORTHWARD ALONG A TIGHTENING BAROCLINIC ZONE. LATEST MODEL RUNS CONTINUE TO HAVE A MODEST AREA OF LOW PRESSURE AT THE SURFACE TRACKING ACROSS EITHER NORTHERN OHIO (MAJORITY OF MODELS) OR SOUTHWEST LOWER MICHIGAN (INCONSISTENT AND CONTINUED OUTLIER NAM). THERE IS STILL THE POTENTIAL FOR LAKE ENHANCEMENT OFF OF LAKE HURON ACROSS NORTHEAST LOWER AS A POCKET OF COLDER AIR (850 MB TEMPS -10 TO -12 C) TRIES TO SYNC UP WITH THE TAIL END OF DEEP SYNOPTIC MOISTURE. OVERALL...A GENERAL LIGHT TO MODERATE SNOWFALL IS STILL EXPECTED WITH STORM TOTAL AMOUNTS OF BETWEEN 4 AND 8 INCHES OF GREASY SNOW WHICH WILL BE COVERED WITH A WINTER WEATHER ADVISORY FOR ALL COUNTIES OF NORTHERN LOWER MICHIGAN. WILL STILL HAVE TO BE COGNIZANT OF POSSIBLE SNEAKY LAKE ENHANCEMENT ADDING TO THE TOTALS ACROSS NORTHEAST LOWER. MEANWHILE...ACROSS EASTERN UPPER...2 TO 3 INCHES OF ACCUMULATION IS EXPECTED. HIGHS RANGING FROM THE UPPER TEENS TO MIDDLE 20S...BUT LIKELY FALLING OFF IN THE AFTERNOON AS COLD AIR ADVECTION KICKS IN. SUNDAY NIGHT...WRAP AROUND MOISTURE/DEFORMATION ZONE AXIS SITS OVER THE REGION. THIS WILL LIKELY BRING SOME LIGHT SNOW...WITH ADDITIONAL ACCUMULATIONS OF ONE TO PERHAPS TWO INCHES. LOWS RANGING FROM THE COLDER SINGLE DIGITS ABOVE ZERO TO THE MIDDLE TEENS. MONDAY AND MONDAY NIGHT...A NORTHERN STREAM TROUGH ALONG WITH ANOTHER SHOT OF ARCTIC AIR (850 MB TEMPS DOWN TO -20 C OR SO) DROPS DOWN INTO THE REGION BRINGING ADDITIONAL CHANCES FOR MAINLY LIGHT SNOW. THE FLOW IS RATHER LIGHT OVERALL BUT MAY STILL BE JUST STRONG ENOUGH TO PRODUCE SOME LAKE EFFECT (GENERALLY OUT OF THE NORTH NORTHWEST). HOWEVER...AM NOT EXPECTING BIG TIME ACCUMULATIONS WITH MODEL SOUNDINGS SHOWING INVERSION HEIGHTS OF ONLY AROUND 3000 FEET OR SO PLUS SNOWFLAKE SIZES WILL LIKELY BE RATHER SMALL. HIGHS MAINLY IN THE TEENS. LOWS RANGING FROM THE COLDER SINGLE DIGITS TO THE MIDDLE TEENS. TUESDAY...PERHAPS SOME LINGERING NORTH NORTHWEST FLOW LAKE EFFECT IN THE MORNING. OTHERWISE...ARCTIC HIGH PRESSURE PRESSES DOWN FROM THE NORTH YIELDING VERY COLD TEMPERATURES AND PERHAPS CLEARING SKIES (IF WE CAN SCOUR OUT THE LIKELY STUBBORN STRATUS). HIGHS ONLY EXPECTED TO RANGE FROM THE UPPER SINGLE DIGITS (ABOVE ZERO) TO THE MIDDLE TEENS. LOWS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO AT NIGHT. WEDNESDAY THROUGH FRIDAY...A PARADE OF SHORT WAVES DROP DOWN THROUGH THE FLOW. EXTENDED MODELS CONTINUE TO VARY ON THE EXACT TIMING AND DETAILS SO WILL NOT GET TOO FANCY...AND HAVE GENERAL CHANCES FOR SNOW SHOWERS. THERE COULD BE SOME LAKE ENHANCEMENT AS WELL FROM TIME TO TIME...BUT PINNING DOWN THE EXACT FLOW REGIMES IS NEARLY IMPOSSIBLE THIS FAR OUT. HIGHS IN THE MIDDLE TO UPPER 20S WEDNESDAY THEN COOLING OFF AGAIN INTO THE UPPER TEENS TO MIDDLE 20S FOR THURSDAY AND THE MIDDLE TEENS TO AROUND 20 FOR FRIDAY. LOWS IN THE TEENS WEDNESDAY NIGHT THEN THE SINGLE DIGITS FOR THURSDAY AND FRIDAY NIGHTS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 628 AM EST SAT DEC 21 2013 A VERY WEAK NORTHERLY LOW LEVEL FLOW WILL DEVELOP THIS MORNING WITH WEAKER THAN ANTICIPATED DRY AIR ADVECTION. THIS WILL KEEP IFR/MVFR CIGS IN FOR THE MOST OF THE DAY...IF NOT ALL OF THE DAY FOR MBL AND POSSIBLY APN/TVC. CAN STILL SEE PLN GOING VFR FOR A PERIOD TODAY. WINDS VEER BACK TO OUT OF AN EASTERLY DIRECTION THROUGH TONIGHT AND INCREASE IN SPEED IN ADVANCE OF DEEPENING LOW PRESSURE THAT WILL WORK INTO THE MID MISSISSIPPI VALLEY BY DAYBREAK. THICKER AND THICKER MID AND UPPER LEVEL SATURATION WILL WORK ITS WAY BACK DOWN TO IFR CIGS OVERNIGHT WITH SNOWS DEVELOPING BY DAYBREAK FOR ALL AIRPORTS EXCEPT MAYBE PLN. CIGS WILL LIKELY FALL BACK INTO IFR/MVFR EARLIER IN THE EVENING HOWEVER...DUE TO COOLING OF THE BL. SNOWS WILL LIKELY TURN IFR FROM A VISIBILITY STANDPOINT. && .MARINE... ISSUED AT 457 AM EST SAT DEC 21 2013 A LIGHT EASTERLY WINDS REGIME WILL BRIEFLY TURN NORTHERLY OVER MANY OF THE NEARSHORE WATERS THIS MORNING...BEFORE RETURNING TO EASTERLY AND INCREASING THROUGH TONIGHT. THIS DUE TO STRENGTHENING LOW PRESSURE THAT WILL LIFT THROUGH DETROIT. A PERIOD OF ADVISORY LEVEL WINDS WILL DEVELOP TONIGHT...BEFORE DYING BACK OFF SUNDAY NIGHT INTO MONDAY WITH THE APPROACH OF HIGHER PRESSURE. THESE LIGHTER WINDS CONTINUE INTO TUESDAY. && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY FROM 1 AM TO 7 PM EST SUNDAY FOR MIZ016>036-041-042. LH...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY FOR LHZ345>349. LM...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY FOR LMZ323-341-342-344>346. LS...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY FOR LSZ321-322. && $$ UPDATE...BA SYNOPSIS...AS SHORT TERM...SD LONG TERM...AS AVIATION...SD MARINE...SD
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
945 AM EST SAT DEC 21 2013 LATEST UPDATE... UPDATE DENSE FOG IS BECOMING AN INCREASING CONCERN THIS MORNING MAINLY ALONG AND SOUTH OF AN EAST-WEST SURFACE BOUNDARY LOCATED JUST NORTH OF I-94. THERE ARE MANY REPORTS OF VISIBILITY AT OR BELOW 1/4 MILE ALONG AND SOUTH OF THIS BOUNDARY. HRRR GUIDANCE PUSHES THE BOUNDARY SOUTH OF THE FORECAST AREA BY THIS AFTERNOON WITH INCREASING WINDS FROM THE NORTHEAST...SO EXPECT DENSE FOG TO BE LESS OF A CONCERN BY AFTERNOON. WILL HIGHLIGHT THE ONGOING FOG CONCERN IN AN UPCOMING WSW UPDATE. RADAR SHOWS THAT PRECIPITATION HAS BEGUN TO OVERSPREAD THE AREA SOUTHEAST OF A MARSHALL TO MASON LINE. WE ARE A LITTLE CONCERNED ABOUT AIR TEMPERATURES STAYING SUFFICIENTLY COLD FOR ICE ACCUMULATION IN THE WARNED AREA. TEMPERATURES AND DEWPOINTS ARE VERY CLOSE TO FREEZING. A POSITIVE FOR FREEZING RAIN IS COLDER AND SLIGHTLY DRIER AIR UPSTREAM TO THE NORTHEAST. ALSO SEVERAL MESONET SITES IN THE AREA ARE REPORTED TEMPERATURES BELOW FREEZING. CURRENT EXPECTATIONS ARE THAT ICE ACCUMULATION ON SECONDARY ROADS AND EXPOSED ROAD SURFACES REMAIN A DEFINITE CONCERN. WILL BE CLOSELY MONITORING TEMPERATURE TRENDS OVER THE NEXT FEW HOURS. .SYNOPSIS... ISSUED AT 329 AM EST SAT DEC 21 2013 A STORM SYSTEM DEVELOPING TO OUR SOUTHWEST WILL BEGIN TO MOVE INTO THE AREA FROM THE SOUTH TODAY AND CONTINUE TO IMPACT THE AREA THROUGH THE DAY ON SUNDAY. THIS SYSTEM WILL BRING MAINLY SNOW TO THE NORTHWEST PORTION OF THE AREA...FREEZING RAIN ACROSS SOUTH CENTRAL AND SOUTHEAST LOWER MICHIGAN...WITH A WINTRY MIX IN BETWEEN. COLDER AIR WILL THEN MOVE IN ACROSS THE AREA LATER ON SUNDAY AND REMAIN IN PLACE MOST OF THE UPCOMING HOLIDAY WEEK. OCCASIONAL CHANCES OF SNOW SHOWERS CAN BE EXPECTED WITH SOME ACCUMULATIONS LIKELY...ESPECIALLY CLOSER TO THE LAKESHORE. && .UPDATE... ISSUED AT 924 AM EST SAT DEC 21 2013 && .SHORT TERM...(TODAY THROUGH SUNDAY NIGHT) ISSUED AT 329 AM EST SAT DEC 21 2013 THE MAIN FOCUS OF THE SHORT TERM IS THE STORM SYSTEM EXPECTED TO IMPACT THE AREA BEGINNING TODAY AND LASTING THROUGH SUNDAY. WE HAVE TRANSITIONED THE HEADLINES FROM THE WATCH...TO AN ICE STORM WARNING ACROSS THE FAR SE CORNER OF THE CWFA. ADVISORIES HAVE BEEN ISSUED FOR THE REMAINDER OF THE CWFA FOR SNOW ACROSS THE NORTH AND A WINTRY MIX ACROSS THE MIDDLE SECTION OF THE CWFA. NO MAJOR CHANGES IN THE FCST HAVE BEEN MADE AS THE CONSENSUS OF THE MODELS IS GENERALLY CONSISTENT WITH THE PREVIOUS RUNS. WE WILL NEED TO DEAL WITH SOME FOG ISSUES ACROSS THE SOUTH THIS MORNING. THE GREATEST IMPACT OF THE INCOMING STORM SYSTEM LOOKS TO BE THE THREAT OF RELATIVELY SIGNIFICANT AMOUNTS OF FREEZING RAIN/ICING EXPECTED ROUGHLY SE OF I-69 LATER TODAY AND INTO THE EARLY OVERNIGHT HOURS TONIGHT. WE EXPECT RAIN AND OR FREEZING RAIN TO START PUSHING UP INTO THE SRN COUNTIES TOWARD THE AFTERNOON TODAY. AREAS ALONG AND SOUTH OF I-94 COULD START OUT BARELY ABOVE FREEZING AT THE ONSET OF PCPN. WE EXPECT ALL PCPN DOWN ACROSS THE SE CORNER TO TRANSITION TO FREEZING RAIN AS THE COLD AND SOMEWHAT DRIER NE FLOW WILL BRING TEMPS DOWN DUE TO ADVECTION AND EVAPORATIVE COOLING. QPF ACROSS THE SE COUNTIES LOOKS TO BE OVER AN INCH THROUGH THE EARLY OVERNIGHT HOURS AS THEY BARELY GET UNDER THE NRN PERIPHERY OF THE BEST MOISTURE AXIS WITH THIS SYSTEM. AN ABOVE FREEZING LAYER ALOFT IS MAINTAINED MOST OF THE TIME AS THE SFC TEMPS DROP TO AROUND OR JUST BELOW FREEZING. NOT ALL OF THIS QPF WILL GO INTO THE ICING EXPECTED DUE TO LATENT HEAT AND RUNOFF PROCESSES. HOWEVER WITH THAT MUCH QPF...EVEN A PORTION OF IT FREEZING WILL CREATE A GOOD COATING OF ICE...UP AROUND HALF AN INCH WILL BE LIKELY. THE TRANSITION IN P-TYPE WILL BE SOMEWHAT TRICKY ACROSS THE CENTRAL PORTION OF THE CWFA NW OF I-69 TO ROUGHLY M-20. HOWEVER WE EXPECT THAT FREEZING RAIN AND SLEET TO BE MORE PREVAILING WITH SOME SNOW POSSIBLE. A SLIGHT ABOVE FREEZING LAYER WILL BE PRESENT WITH THE LAYER THINNER AND COOLER AS YOU MOVE NW. QPF AMOUNTS WILL BE QUITE A BIT LESS AS THE MOISTURE AXIS REMAINS SE OF THIS AREA. IT WILL BE TOUGH TO GET HIGH IMPACT FREEZING RAIN AMOUNTS IN THIS AREA. HOWEVER ONE THING TO CONSIDER IS THE GLAZE IN PLACE ALREADY FROM THE THU NIGHT/FRI EVENT. THE PCPN IN BOTH OF THESE AREAS IS EXPECTED TO LIGHTEN UP SIGNIFICANTLY BETWEEN 06-12Z SUN AS THE DRY SLOT IS EXPECTED TO MOVE OVER THESE AREAS. SOME LIGHT PCPN WILL REMAIN...HOWEVER WE COULD SEE IT TRANSITION TO FZDZ AS THE DGZ BECOMES UNSATURATED. BY THE TIME PCPN REACHES THE NRN PORTION OF THE CWFA...THE COLUMN SHOULD BE MAINLY COLD ENOUGH TO SUPPORT MAINLY SNOW. THE SNOW SHOULD START OUT LIGHT...AND PICK UP LATE TONIGHT/SUN MORNING AS THE BEST DEFORMATION SLIDES ACROSS THE NRN COUNTIES AND NW OF THE CWFA. SNOW AMOUNTS ARE GENERALLY EXPECTED TO REMAIN IN THE ADVISORY CATEGORY AS THE UPPER LOW EJECTING WILL HAVE OPENED UP BY THE TIME IT REACHES HERE AND THE FGEN IN THE DEFORMATION WILL NOT BE AS STRONG AS TO OUR SW. ONE THING GOING FOR BETTER SNOW AMOUNTS HERE IS THE FACT THAT THE DGZ IS EXPECTED TO REMAIN SATURATED AS THE DRY SLOT REMAINS SE OF THIS AREA. THE CAVEAT TO ALL OF THIS IS IF THE OUTLIER NAM IS CORRECT...ALL OF THIS WOULD BE SHIFTING TO THE NW A LITTLE. WE BELIEVE AT THIS TIME THAT WE HAVE A GOOD CONSENSUS OF THE TRACK OF THE SYSTEM WITH GOOD RUN TO RUN CONSISTENCY FROM MOST OF THE GLOBAL MODELS AND IT SHOULD BE WELL SAMPLED BY NOW WITH IT BEING WELL WITHIN THE RAOB NETWORK. WE WILL SEE A TRANSITION TO SOME LAKE EFFECT SNOW SHOWERS ON SUN NIGHT AS COLDER AIR COMES IN BEHIND THE SYSTEM. THE FLOW SHOULD BE NNW WHICH WOULD FAVOR THE IMMEDIATE LAKESHORE FOR BEST SNOW SHOWER CHANCES. THERE IS SOME DECENT MOISTURE UP THROUGH 15K FEET AND OVER-LAKE INSTABILITY IS SUFFICIENT. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 329 AM EST SAT DEC 21 2013 THE UPCOMING CHRISTMAS WEEK WILL BE MORE LIKE WHAT WE HAVE SEEN FOR MUCH OF DECEMBER: COLDER THAN NORMAL WITH FREQUENT CHANCES FOR SNOW SHOWERS. THE NORTHERN BRANCH OF THE JET AND ARCTIC AIR WILL DOMINATE THROUGHOUT THE WEEK... WITH SEVERAL SHORTWAVES AND SFC TROUGHS/FRONTS SWINGING THROUGH THE GRTLKS RGN. TEMPERATURES ARE EXPECTED BE BELOW FREEZING ALL WEEK... AND THE COLDEST DAY OF THE WEEK WILL BE TUESDAY WHEN HIGHS SHOULD STRUGGLE TO REACH 20 BEHIND THE FIRST NRN STREAM WAVE. GFS/ECMWF ARE IN GOOD AGREEMENT SHOWING A POTENT SHORTWAVE IMPACTING THE AREA MONDAY AFTERNOON AND NIGHT. SNOW SHOWERS ARE LIKELY AND LAKE ENHANCEMENT WILL BE IN PLAY AS THIS FEATURE COMES THROUGH. HOWEVER CONFIDENCE IN WIND DIRECTION IS LOW SINCE MODELS INDICATE A WEST TO EAST ORIENTED SFC TROUGH SETTING UP SOMEWHERE ACROSS LWR MI AND ARE NOT IN GREAT AGREEMENT WITH IT/S LOCATION AND RESULTANT WINDS. NEVERTHELESS THE TROUGH SHOULD RESULT IN LOCALLY ENHANCED CONVERGENCE WITH A LARGE PORTION OF THE CWFA SEEING SNOW SHOWERS AND AT LEAST SOME LIGHT ACCUMULATIONS. IF A WESTERLY FLOW DEVELOPS THEN AREAS ALONG AND WEST OF HWY 131 COULD SEE SEVERAL INCHES BUT AGAIN WIND DIRECTION IS VERY QUESTIONABLE AT THIS TIME. A BRIEF PERIOD OF SHORTWAVE RIDGING MOVES ACROSS FOR TUESDAY AFTERNOON AND EVENING... THEN SOME WAA/ISENTROPIC LIFT LIGHT SNOW POSSIBLE ON CHRISTMAS DAY AHEAD OF THE NEXT APPROACHING SHORTWAVE. THE ECMWF HAS A MUCH STRONGER SHORTWAVE THAN THE GFS FOR THE 26TH AND WOULD SUGGEST A DECENT ROUND OF ACCUMULATING LAKE ENHANCED SNOW SHOWERS FOR THURSDAY AND THURSDAY NIGHT. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 706 AM EST SAT DEC 21 2013 WIDESPREAD LIFR CONDITIONS DUE TO LOW CLOUDS AND FOG WILL CONTINUE TO PLAGUE ALL OF THE TERMINALS TODAY AND TONIGHT. FREEZING RAIN WILL BREAK OUT AGAIN THIS AFTERNOON... STARTING EARLY THIS AFTERNOON ALONG THE I-94 CORRIDOR THEN SPREADING NORTH TO THE I-96 CORRIDOR BY LATE AFTERNOON WHERE SOME SLEET AND SNOW MAY MIX WITH THE FREEZING RAIN AT THE ONSET. MKG SHOULD TEND TO BE MOSTLY SNOW AND SLEET AS PRECIP DEVELOPS THERE EARLY THIS EVENING. THE INTENSITY OF THE FREEZING RAIN/ICING IS EXPECTED TO BE HEAVIEST DURING THE EVENING HOURS THEN DIMINISH AFTER 06Z TONIGHT. MKG SHOULD BE THE EXCEPTION TO THIS... WHERE SNOW WILL CONTINUE OVERNIGHT. && .MARINE... ISSUED AT 534 PM EST FRI DEC 20 2013 NORTHEAST FLOW WILL CONTINUE INTO SATURDAY NIGHT. THIS OFFSHORE FLOW WILL HELP KEEP WAVES LOWER. HOWEVER AS WINDS PIVOT TO THE NORTH NORTHWEST LATE SATURDAY NIGHT/EARLY SUNDAY MORNING WAVES WILL BUILD AND WE WILL LIKELY NEED A SMALL CRAFT ADVISORY BY THEN. && .HYDROLOGY... ISSUED AT 325 PM EST FRI DEC 20 2013 THE FORECAST TREND IS TOWARDS LESS QPF OVER THE WEEKEND AS THE TRACK OF THE LOW LOOKS TO STAY FURTHER SOUTH AND EAST OF THE RIVER BASINS IN SOUTHWEST LOWER MICHIGAN. TOTAL QPF IS NOW EXPECTED TO BE LESS THAN AN INCH FOR THE HEADWATERS OF THE GRAND AND ST. JOSEPH BASINS. SHARP RISES ARE STILL POSSIBLE AT THE JACKSON FORECAST POINT ON THE GRAND RIVER AND WE WILL HAVE TO WATCH THE MODEL TRENDS CLOSELY TONIGHT AND THE ACTUAL STORM DEVELOPMENT ON SATURDAY. SNOW MELT COULD ALSO CONTRIBUTE TO RISES ACROSS THE ST. JOSEPH AND KALAMAZOO BASINS BEFORE THE ARCTIC AIR RETURNS ON MONDAY...WITH ICE REFORMING ON THE RIVERS. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO NOON EST SUNDAY FOR MIZ051-052-056>059-064-065-071-072. ICE STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST SUNDAY FOR MIZ066-067-073-074. WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY FOR MIZ037>040-043>046-050. LM...NONE. && $$ UPDATE...TJT SYNOPSIS...NJJ SHORT TERM...NJJ LONG TERM...MEADE AVIATION...MEADE HYDROLOGY...OSTUNO MARINE...JK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
643 AM EST SAT DEC 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 457 AM EST SAT DEC 21 2013 SW FLOW ALOFT BTWN UPPER LOW OVER HUDSON BAY AND STRONG SOUTHERN STREAM DISTURBANCE OVER NEW MEXICO. THROUGH TONIGHT...MAIN ISSUES ARE TIED TO LAKE EFFECT. SOUTHERN STREAM WAVE LIFTS TOWARD UPPER GREAT LAKES LATER TONIGHT...THOUGH IT APPEARS MAJORITY OF WIDESPREAD SNOW WITH THE DEVELOPING LOW PRESSURE SYSTEM WILL REMAIN JUST SOUTH OF CWA UNTIL DAYBREAK ON SUNDAY. EMBEDDED SHORTWAVES/PV ANOMALIES IN FLOW ALOFT HELPING TO SUSTAIN LGT SNOW/FLURRIES OVER CWA EARLY THIS MORNING. ALSO A BAND OF ENHANCED LK EFFECT MAINLY OVER SCNTRL AND SOUTHEAST PORTIONS OF LK SUPERIOR. RAP...WHICH DOES HAVE DECENT HANDLE ON BACK EDGE OF LGT SNOW CURRENTLY...INDICATES MID-LEVEL MOISTURE/UVM EXITS EAST HALF OF CWA THROUGH AROUND DAYBREAK THIS MORNING SO WOULD EXPECT LGT SNOW TO END FOR A TIME. AT THE LEAST THE CLOUDS WILL CONTINUE TO HOLD UP TEMPS THIS MORNING MAINLY IN THE TEENS. MILD FOR SURE COMPARED TO THE RECENT CHILL UPR LAKES HAS EXPERIENCED. CURRENTLY THERE IS A SFC TROUGH ACROSS THE AREA EXTENDING TO THE NW OF SFC LOW NEAR DETROIT. EXPECT TROUGHING TO PERSIST THROUGH MUCH OF THE DAY WHILE GRADUALLY GETTING PUSHED TO THE SOUTH AND EAST BY THIS AFTN AS HIGH PRESSURE OVR SASKATCHEWAN AND MANITOBA TRIES TO RIDGE ACROSS LK SUPERIOR REGION. THE MAIN IMPACT THIS HAS IS ON WIND FIELDS AND ASSOCIATED LAKE EFFECT AS THERE IS ENOUGH INSTABILITY WITH INVERSIONS UP TO 5-7KFT AND TEMPS AT INVERSION TOP AROUND -13C WHILE WATER TEMPS ARE AROUND +3C. SOUNDINGS AT P59/CMX AND STDM4 INDICATE DECENT SUBSIDENCE ABOVE MOIST LAKE EFFECT LAYER AND ALSO NOT AS MUCH LIFT WITHIN THE DGZ. IF CONVERGENCE CAN PERSIST OVER THE KEWEENAW TODAY...THEN THERE IS AN OPPORTUNITY FOR ADVY LEVEL SNOW AMOUNTS. CONFIDENCE IS LOW ON THIS POTENTIAL AND EVEN LOWER ON EXACTLY WHERE THAT WOULD OCCUR. FOLLOWED GEM-REGIONAL THROUGH TODAY FOR WINDS ALONG WITH NAM AND LOCAL-WRF MODEL BASED ON RAP BOUNDARY CONDITIONS. THIS BLEND ESSENTIALLY HANGS UP MAIN CONVERGENCE AREA OVER NORTHERN KEWEENAW THEN EVENTUALLY DRAWS IT SOUTH ACROSS THE PENINSULA THIS AFTN AS THE HIGH BUILDS TOWARD LK SUPERIOR. SINCE INSTABILITY IS NOT EXTREME OR OVER THE TOP BY ANY MEANS...FCST SNOW AMOUNTS FROM 2-4 INCHES...GREATEST NEAR MOHAWK/EAGLE RIVER/COPPER HARBOR. DESPITE MODELS NOT SHOWING MUCH OCCURRING FOR OTHER AREAS WHERE FLOW IS ONSHORE NEAR LK SUPERIOR...WENT WITH PERSISTENCE AND KEPT MENTION OF SNOW OVER FAR WESTERN UPR MICHIGAN AND ALSO IN NCNTRL UPR MICHIGAN. ANY AMOUNTS FOR THESE AREAS TODAY WILL JUST A DUSTING OF LESS THAN 1 INCH. MINOR ISSUE FOR TODAY IS SKY COVER AND TEMPS. MODELS STRUGGLING WITH EVENTUAL EVOLUTION OF LOW MVFR CLOUDS FM LK SUPERIOR BACK INTO CNTRL MINNESOTA. NAM/RAP/GEM-REGIONAL SHOW THESE CLOUDS TO START BUT SEEM TOO QUICK TO GET RID OF THEM OVER ALL BUT WESTERN CWA BY LATER MORNING. WE WILL SEE ON THIS. IF MORE SUN OCCURS...MAX TEMPS MAY PUSH WELL INTO THE MID-UPR 20S CNTRL. BASED ON CURRENT SATELLITE/OBS TRENDS AND WITH SUN ANGLE ABOUT AS LOW AS IT GETS...WILL KEEP SKIES MOSTLY CLOUDY FOR TODAY. LATER TODAY WILL BE A MOOT POINT AS INCREASING NE WINDS SHOULD RESULT IN EXPANSION OF CLOUDS OFF LK SUPERIOR. SOUTHERN STREAM WAVE/LOW PRESSURE SYSTEM AFFECTS WILL BE KNOCKING ON THE DOOR OF UPR MICHIGAN SO TO SPEAK LATER TONIGHT. NAM/GFS/ECMWF LOOKED SIMILAR WITH PLACEMENT OF H5 TROUGH/PRIMARY PV ANAMOLY/H85 AND SFC LOWS. GEM WAS FARTHER NORTH WITH H85 LOW. SEEMED THAT ECMWF WAS A NICE MIDDLE GROUND BTWN FARTHER SOUTH NAM/GFS WITH ADVANCING WIDESPREAD SNOW AND MORE AGRESSIVE GEM. BROUGHT LIKELY POPS FOR SYNOPTIC SNOW INTO FAR SCNTRL BY 09Z SUNDAY. OTHER IMPACT WILL BE INCREASING FAVORABLE LAKE EFFECT OVER FAR WEST/KEWEENAW AND NCNTRL CWA. NOT EXPECTING A LOT OF SNOW AS ANY LARGE SCALE FORCING IS MINIMAL THROUGH 12Z...BUT THERE IS ENOUGH EVIDENCE IN FCST SOUNDINGS THAT LAKE EFFECT WILL BE DEVELOPED ENOUGH TO RESULT IN LIKELY POPS WITH MINOR SNOW AMOUNTS. SETUP BECOMES MUCH MORE FAVORABLE FOR SIGNIFICANT LAKE ENHANCEMENT FOR SUNDAY AND BEYOND. BTWN THE LAKE EFFECT MOISTURE/SNOW AND MID-HIGH CLOUDS ARRIVING FROM THE SOUTH...EXPECT TEMPS TONIGHT TO STAY IN THE TEENS AGAIN. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 457 AM EST SAT DEC 21 2013 HAVE OPTED TO ISSUE A WINTER STORM WATCH FOR THE TERRAIN/LAKE ENHANCED AREAS OF MARQUETTE/BARAGA COUNTIES AS WELL AS GOGEBIC AND ONTONAGON COUNTIES FOR SUNDAY AND MONDAY. LONG DURATION LAKE ENHANCED/LAKE EFFECT SNOW EPISODE LOOKING MORE POSSIBLE NOW AS THE MODELS ARE STARTING TO COME INTO BETTER AGREEMENT INTO A MAIN LOW TRACK THROUGH SOUTHERN MI ON SUNDAY. HOWEVER...THE COMPLEX INTERACTION BETWEEN THE SOUTHERN STREAM ENERGY MOVING THROUGH THE LOWER LAKES AND THE NORTHERN STREAM TROUGH MOVING INTO THE UPPER MIDWEST MAKES THIS FORECAST CONFIDENCE STILL SOMEWHAT BELOW AVERAGE. ONTO THE DETAILS...AS SAID ABOVE THE NWP SUITE HAVE COME INTO BETTER AGREEMENT WITH THE MAIN LOW MOVING THROUGH SOUTHERN LOWER MICHIGAN WITH THE SOUTHERN STREAM IMPULSE MOVING OUT OF THE PLAINS. EXPECT SYNOPTIC MOISTURE AND LIFT TO GLANCE BY THE SOUTHEAST FORECAST AREA SUNDAY MORNING INTO EARLY AFTERNOON AS THE COMMA HEAD/DEFORMATION ZONE PCPN MOVES THROUGH. THIS TRACK WILL ALLOW FOR 1000-850MB WINDS TO TURN NE AND SHOULD ALLOW FOR LAKE ENHANCEMENT TO ALSO DEVELOP IN MARQUETTE/BARAGA COUNTIES AS WELL AS THE FAR WEST NEAR IRONWOOD. CONSENSUS QPF FROM THE NWP SUGGEST ABOUT 0.20-0.30 INCH OF QPF NEAR LAKE MICHIGAN AND FAR EAST ON SUNDAY...WITH MUCH LESSER AMOUNTS WELL INLAND AWAY FROM FROM LAKE SUPERIOR. THIS ALSO SEEMS REASONABLE GIVEN THAT 700MB MIXING RATIOS REMAIN AROUND 2 G/KG THROUGH EARLY AFTERNOON. GIVEN THAT SOME OF THE LIFT WILL BE IN THE DGZ AREA ACROSS THE SOUTH DURING THE DAY...WE SHOULD SEE SNOW RATIOS ACROSS THE FAR SOUTHEAST AROUND 15-17:1 DURING THE DAY WHICH WOULD EQUATE TO 3-5 INCHES OF SNOW BY EVENING. MOST LIKELY AN ADVISORY WILL BE NEEDED IN THIS AREA ON SUNDAY...BUT WILL HOLD OFF SINCE THIS WILL BE GENERALLY A 3RD PERIOD ADVY. AS FOR AREAS CLOSER TO LAKE SUPERIOR...ALL OF THE NWP GUIDANCE SHOW PBL WINDS STAYING NELY THROUGH THE DAY WHICH SHOULD ALLOW FOR TERRAIN ENHANCED SNOW TO COMMENCE IN THE NE FLOW FAVORED AREAS DESPITE THE RELATIVELY WEAK SYNOPTIC LIFT. WITH THE BEST LIFT BEING CONFINED TO GENERALLY BELOW THE DGZ...EXPECT SNOW RATIOS BE BE FAIRLY LOW WITH ONLY AROUND 13:1. WILL GENERALLY GO WITH 4 OR 5 INCHES AT MOST IN THESE AREAS...BUT GIVEN THE STRONG AND DEEP NE FLOW...WOULD NOT BE SHOCKED IF QPF AND THUS SNOWFALL IS MORE ON SUNDAY. THEN ON SUNDAY NIGHT...DIFFERENCE START TO DEVELOP WITH THE MODELS REGARDING THE EVOLUTION OF THE NORTHERN STREAM UPPER TROUGH. THE NAM IS CERTAINLY THE MOST AGGRESSIVE IN CLOSING OFF THE LOW AND SETTLING OVER THE UPPER GREAT LAKES...WHICH ALLOW FOR A STRONG INVERTED TROUGH TO HANG BACK ACROSS THE CENTRAL GREAT LAKES THROUGH MONDAY. MEANWHILE...THE GFS GENERALLY KEEPS THE UPPER TROUGH OPEN AND MOVES IN THROUGH THE AREA BY MONDAY AFTERNOON. THE LATEST 00Z ECMWF IS INTERESTING AS IT ALSO ATTEMPT TO CLOSE OFF THE LOW SUN NIGHT BUT IS NOT NEARLY AS DEEP AS THE NAM FORECASTS. NONETHELESS...THE ECMWF ALSO SUGGESTS THAT THERE WILL BE SOME TYPE OF INVERTED TROUGH EXTENDING BACK INTO THE AREA THROUGH MONDAY AND OUR LOCALLY PRODUCE ARW-WRF USING THE GFS AS BOUNDARY CONDITIONS ALSO SUGGEST THAT THERE WILL BE A INVERTED TROUGH HANGING BACK THROUGH MONDAY. AS SUCH...DO NOT THINK THE PBL WINDS WILL SHIFT TO N-NW AS FAST AS THE GFS AND ECMWF SUGGEST. IN FACT...THE CURRENT THINKING IS THAT THE WINDS WILL STAY NORTHERLY OR PERHAPS A LITTLE EAST OF NORTH THROUGH MONDAY WITH THIS TROUGH STAYING SOUTH OF THE AREA. WITH ALL OF THIS SAID...THE EXPECTATION IS THAT THE SNOW WILL TRANSITION TO MORE LAKE ENHANCED VARIETY AND PERSIST RIGHT THROUGH MONDAY BEFORE THE UPPER TROUGH SWINGS THROUGH AND ALLOWS THE WIND TO GRADUALLY SHIFT TO THE N-NW BY MON EVENING. AS SUCH...EXPECT MODERATE TO LOCALLY HEAVY SNOW TO CONTINUE IN MQT/BARAGA COUNTIES AS WELL AS GOGEBIC COUNTY THROUGH THE NIGHT SUNDAY INTO MONDAY. THE BEST LIFT RAPIDLY BECOMING ENTRENCHED IN THE DGZ SUNDAY EVENING AS THE UPPER TEMPS DROP...EXPECT THE SNOW TO BECOME MUCH MORE FLUFFY BUT ALSO ACCUMULATE MUCH FASTER WITH RATIOS CLOSE TO 25:1 BY MON MORNING. SOME AREAS IN THE WATCH AREA COULD SEE ANOTHER 8-12 INCHES OF SNOW SUN NIGHT INTO MONDAY. INTERESTINGLY...THERE ARE SEVERAL VERY GOOD CIPS ANALOG EVENTS FOR THIS SYSTEM. THEY ALL GENERALLY SHOW THE WATCH AREA SEEING SIGNIFICANT 72 HOUR SNOWFALL. NOT SURE IF WE WILL SEE ANY LONGER PERIOD OF HEAVY SNOWFALL...RATHER I AM THINKING THAT IT WILL BE GENERALLY A PERSISTENT SNOWFALL FOR 24-36 HOURS WHICH WILL ALLOW WARNING CRITERIA TO BE REACHED. EVEN MORE INTERESTING...DESPITE THE FACT THAT GOGEBIC COUNTY WILL BE FURTHEST REMOVED FROM THE SYSTEM...THE CURRENT NWP AND ALSO THE CIPS GUIDANCE SUGGEST THAT THIS AREA COULD SEE THE MOST SNOWFALL OUT OF THIS EVENT. WE WILL SEE... ANY REMAINING LES SHOULD END RAPIDLY MON NIGHT/TUE MORNING AS THE HIGH PRES RIDGE BUILDS ACROSS THE FORECAST AREA. STILL LOOKS QUITE COLD TUE MORNING ACROSS THE WEST WITH LIGHT WINDS/CLEAR SKIES. TEMPS 10-20 BELOW NOT OUT OF THE QUESTION IN THE NORMALLY COLDER SPOTS. THE ECMWF AND GEM ARE IN GOOD AGREEMENT IN LIGHT OVERRUNNING/WARM ADVECTION SNOW CHRISTMAS EVE NIGHT INTO CHRISTMAS DAY ACROSS THE ENTIRE FORECAST AREA. SOME HINTS THAT THERE MIGHT BE SOME LAKE ENHANCEMENT OFF OF LAKE MICHIGAN TUESDAY NIGHT AND HAVE OPTED TO CONTINUE LIKELY POPS ACROSS THE EASTERN PART OF THE FORECAST AREA TUE NIGHT INTO CHRISTMAS DAY. SOME DIFFERENCES EMERGE THU INTO FRIDAY REGARDING THE EVOLUTION AND THE TROUGH WITH THE ECMWF BEING DEEPER AND FURTHER SOUTH COMPARED TO THE GFS. REGARDLESS...SENSIBLE WEATHER SHOULD GENERALLY THE SAME WITH EITHER MODEL WITH LES IN THE NW FAVORED SNOWBELTS CHRISTMAS NIGHT INTO THU NIGHT BEFORE DIMINISHING ON FRIDAY AS HIGH PRES BUILDS OVERHEAD. TEMPS STILL LOOK BELOW NORMAL THROUGH THE EXTENDED WITH 850MB TEMPS -20 TO -25C WED NIGHT/THU WARMING TO -15 TO -20C BY FRIDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 640 AM EST SAT DEC 21 2013 WITH ABUNDANT LOW LEVEL MOISTURE AND LIGHT WINDS ACROSS THE REGION...MAINLY MVFR CIGS ARE EXPECTED THROUGH THE FCST PERIOD AT CMX AND IWD. EXPECT LAKE EFFECT SNOW SHOWERS TO DEVELOP AT CMX LATER TODAY AND THESE WILL CONTINUE THROUGH TONIGHT. IFR VSBY IS EXPECTED IN THE SNOW AND ALSO DUE TO BLSN WITH GUSTY EAST WINDS DEVELOPING. SNOW SHOWERS WILL BEGIN TO AFFECT IWD LATE TONIGHT AS WINDS BECOME MORE NORTHEAST. WEAK DOWNSLOPE WESTERLY FLOW AT SAW WILL FAVOR VFR CONDITIONS UNTIL LATE THIS AFTERNOON WHEN WINDS VEER TO THE NNE AND UPSLOPE FLOW LEADS TO MVFR CIGS AND SOME LIGHT SNOW SHOWERS. WINDS BECOMING MORE EASTERLY WILL SCATTER OUT THE LOW CLOUDS AT SAW LATE TONIGHT. WIDESPREAD SNOW IS EXPECTED TO IMPACT ALL TERMINALS ON SUNDAY AS A LOW PRESSURE SYSTEM SLIDES ACROSS THE CENTRAL GREAT LAKES REGION. HEAVIEST SNOW WILL OCCUR AT IWD WITH UPSLOPE NORTHEAST WINDS PROVIDING ADDITIONAL SUPPORT FOR SNOW OFF LK SUPERIOR. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 457 AM EST SAT DEC 21 2013 LIGHT WINDS TODAY WITH TROUGH OVER THE LAKE THEN AS THE TROUGH SINKS SOUTH TONIGHT...EXPECT STRONG AND GUSTY NORTHEAST WINDS TO 30 KTS OVER MUCH OF LAKE SUPERIOR INTO SUNDAY...FURTHER STRENGTHENED BY LOW PRESSURE LIFTING ACROSS LOWER MICHIGAN. COULD BE GALE GUSTS OVER THE WEST WITH CHANNELING BETWEEN MINNESOTA SHORELINE AND KEWEENAW PENINSULA. DURING THIS PERIOD OF STRONGER WINDS THERE WILL BE FREEZING SPRAY. EXPECT THE LOW TO LINGER A SURFACE TROUGH OVER THE UPPER GREAT LAKES THROUGH MONDAY AND KEEP WINDS UP TO 25 KTS. HIGH PRESSURE WILL CROSS THE UPPER GREAT LAKES ON MONDAY NIGHT...WHILE A LOW PRESSURE SYSTEM BEGINS TO TAKE SHAPE IN THE CANADIAN PRAIRIES. THIS LOW WILL LEAD TO INCREASING SOUTHERLY WINDS ACROSS LAKE SUPERIOR ON TUESDAY. WHEN THE LOW MOVES THROUGH THE REGION ON WEDNESDAY...WINDS WILL BECOME WESTERLY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER STORM WATCH FROM SUNDAY MORNING THROUGH MONDAY EVENING FOR MIZ002-004-005-009. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...MRD AVIATION...JLA MARINE...JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
459 AM EST SAT DEC 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 457 AM EST SAT DEC 21 2013 SW FLOW ALOFT BTWN UPPER LOW OVER HUDSON BAY AND STRONG SOUTHERN STREAM DISTURBANCE OVER NEW MEXICO. THROUGH TONIGHT...MAIN ISSUES ARE TIED TO LAKE EFFECT. SOUTHERN STREAM WAVE LIFTS TOWARD UPPER GREAT LAKES LATER TONIGHT...THOUGH IT APPEARS MAJORITY OF WIDESPREAD SNOW WITH THE DEVELOPING LOW PRESSURE SYSTEM WILL REMAIN JUST SOUTH OF CWA UNTIL DAYBREAK ON SUNDAY. EMBEDDED SHORTWAVES/PV ANOMALIES IN FLOW ALOFT HELPING TO SUSTAIN LGT SNOW/FLURRIES OVER CWA EARLY THIS MORNING. ALSO A BAND OF ENHANCED LK EFFECT MAINLY OVER SCNTRL AND SOUTHEAST PORTIONS OF LK SUPERIOR. RAP...WHICH DOES HAVE DECENT HANDLE ON BACK EDGE OF LGT SNOW CURRENTLY...INDICATES MID-LEVEL MOISTURE/UVM EXITS EAST HALF OF CWA THROUGH AROUND DAYBREAK THIS MORNING SO WOULD EXPECT LGT SNOW TO END FOR A TIME. AT THE LEAST THE CLOUDS WILL CONTINUE TO HOLD UP TEMPS THIS MORNING MAINLY IN THE TEENS. MILD FOR SURE COMPARED TO THE RECENT CHILL UPR LAKES HAS EXPERIENCED. CURRENTLY THERE IS A SFC TROUGH ACROSS THE AREA EXTENDING TO THE NW OF SFC LOW NEAR DETROIT. EXPECT TROUGHING TO PERSIST THROUGH MUCH OF THE DAY WHILE GRADUALLY GETTING PUSHED TO THE SOUTH AND EAST BY THIS AFTN AS HIGH PRESSURE OVR SASKATCHEWAN AND MANITOBA TRIES TO RIDGE ACROSS LK SUPERIOR REGION. THE MAIN IMPACT THIS HAS IS ON WIND FIELDS AND ASSOCIATED LAKE EFFECT AS THERE IS ENOUGH INSTABILITY WITH INVERSIONS UP TO 5-7KFT AND TEMPS AT INVERSION TOP AROUND -13C WHILE WATER TEMPS ARE AROUND +3C. SOUNDINGS AT P59/CMX AND STDM4 INDICATE DECENT SUBSIDENCE ABOVE MOIST LAKE EFFECT LAYER AND ALSO NOT AS MUCH LIFT WITHIN THE DGZ. IF CONVERGENCE CAN PERSIST OVER THE KEWEENAW TODAY...THEN THERE IS AN OPPORTUNITY FOR ADVY LEVEL SNOW AMOUNTS. CONFIDENCE IS LOW ON THIS POTENTIAL AND EVEN LOWER ON EXACTLY WHERE THAT WOULD OCCUR. FOLLOWED GEM-REGIONAL THROUGH TODAY FOR WINDS ALONG WITH NAM AND LOCAL-WRF MODEL BASED ON RAP BOUNDARY CONDITIONS. THIS BLEND ESSENTIALLY HANGS UP MAIN CONVERGENCE AREA OVER NORTHERN KEWEENAW THEN EVENTUALLY DRAWS IT SOUTH ACROSS THE PENINSULA THIS AFTN AS THE HIGH BUILDS TOWARD LK SUPERIOR. SINCE INSTABILITY IS NOT EXTREME OR OVER THE TOP BY ANY MEANS...FCST SNOW AMOUNTS FROM 2-4 INCHES...GREATEST NEAR MOHAWK/EAGLE RIVER/COPPER HARBOR. DESPITE MODELS NOT SHOWING MUCH OCCURRING FOR OTHER AREAS WHERE FLOW IS ONSHORE NEAR LK SUPERIOR...WENT WITH PERSISTENCE AND KEPT MENTION OF SNOW OVER FAR WESTERN UPR MICHIGAN AND ALSO IN NCNTRL UPR MICHIGAN. ANY AMOUNTS FOR THESE AREAS TODAY WILL JUST A DUSTING OF LESS THAN 1 INCH. MINOR ISSUE FOR TODAY IS SKY COVER AND TEMPS. MODELS STRUGGLING WITH EVENTUAL EVOLUTION OF LOW MVFR CLOUDS FM LK SUPERIOR BACK INTO CNTRL MINNESOTA. NAM/RAP/GEM-REGIONAL SHOW THESE CLOUDS TO START BUT SEEM TOO QUICK TO GET RID OF THEM OVER ALL BUT WESTERN CWA BY LATER MORNING. WE WILL SEE ON THIS. IF MORE SUN OCCURS...MAX TEMPS MAY PUSH WELL INTO THE MID-UPR 20S CNTRL. BASED ON CURRENT SATELLITE/OBS TRENDS AND WITH SUN ANGLE ABOUT AS LOW AS IT GETS...WILL KEEP SKIES MOSTLY CLOUDY FOR TODAY. LATER TODAY WILL BE A MOOT POINT AS INCREASING NE WINDS SHOULD RESULT IN EXPANSION OF CLOUDS OFF LK SUPERIOR. SOUTHERN STREAM WAVE/LOW PRESSURE SYSTEM AFFECTS WILL BE KNOCKING ON THE DOOR OF UPR MICHIGAN SO TO SPEAK LATER TONIGHT. NAM/GFS/ECMWF LOOKED SIMILAR WITH PLACEMENT OF H5 TROUGH/PRIMARY PV ANAMOLY/H85 AND SFC LOWS. GEM WAS FARTHER NORTH WITH H85 LOW. SEEMED THAT ECMWF WAS A NICE MIDDLE GROUND BTWN FARTHER SOUTH NAM/GFS WITH ADVANCING WIDESPREAD SNOW AND MORE AGRESSIVE GEM. BROUGHT LIKELY POPS FOR SYNOPTIC SNOW INTO FAR SCNTRL BY 09Z SUNDAY. OTHER IMPACT WILL BE INCREASING FAVORABLE LAKE EFFECT OVER FAR WEST/KEWEENAW AND NCNTRL CWA. NOT EXPECTING A LOT OF SNOW AS ANY LARGE SCALE FORCING IS MINIMAL THROUGH 12Z...BUT THERE IS ENOUGH EVIDENCE IN FCST SOUNDINGS THAT LAKE EFFECT WILL BE DEVELOPED ENOUGH TO RESULT IN LIKELY POPS WITH MINOR SNOW AMOUNTS. SETUP BECOMES MUCH MORE FAVORABLE FOR SIGNIFICANT LAKE ENHANCEMENT FOR SUNDAY AND BEYOND. BTWN THE LAKE EFFECT MOISTURE/SNOW AND MID-HIGH CLOUDS ARRIVING FROM THE SOUTH...EXPECT TEMPS TONIGHT TO STAY IN THE TEENS AGAIN. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 457 AM EST SAT DEC 21 2013 HAVE OPTED TO ISSUE A WINTER STORM WATCH FOR THE TERRAIN/LAKE ENHANCED AREAS OF MARQUETTE/BARAGA COUNTIES AS WELL AS GOGEBIC AND ONTONAGON COUNTIES FOR SUNDAY AND MONDAY. LONG DURATION LAKE ENHANCED/LAKE EFFECT SNOW EPISODE LOOKING MORE POSSIBLE NOW AS THE MODELS ARE STARTING TO COME INTO BETTER AGREEMENT INTO A MAIN LOW TRACK THROUGH SOUTHERN MI ON SUNDAY. HOWEVER...THE COMPLEX INTERACTION BETWEEN THE SOUTHERN STREAM ENERGY MOVING THROUGH THE LOWER LAKES AND THE NORTHERN STREAM TROUGH MOVING INTO THE UPPER MIDWEST MAKES THIS FORECAST CONFIDENCE STILL SOMEWHAT BELOW AVERAGE. ONTO THE DETAILS...AS SAID ABOVE THE NWP SUITE HAVE COME INTO BETTER AGREEMENT WITH THE MAIN LOW MOVING THROUGH SOUTHERN LOWER MICHIGAN WITH THE SOUTHERN STREAM IMPULSE MOVING OUT OF THE PLAINS. EXPECT SYNOPTIC MOISTURE AND LIFT TO GLANCE BY THE SOUTHEAST FORECAST AREA SUNDAY MORNING INTO EARLY AFTERNOON AS THE COMMA HEAD/DEFORMATION ZONE PCPN MOVES THROUGH. THIS TRACK WILL ALLOW FOR 1000-850MB WINDS TO TURN NE AND SHOULD ALLOW FOR LAKE ENHANCEMENT TO ALSO DEVELOP IN MARQUETTE/BARAGA COUNTIES AS WELL AS THE FAR WEST NEAR IRONWOOD. CONSENSUS QPF FROM THE NWP SUGGEST ABOUT 0.20-0.30 INCH OF QPF NEAR LAKE MICHIGAN AND FAR EAST ON SUNDAY...WITH MUCH LESSER AMOUNTS WELL INLAND AWAY FROM FROM LAKE SUPERIOR. THIS ALSO SEEMS REASONABLE GIVEN THAT 700MB MIXING RATIOS REMAIN AROUND 2 G/KG THROUGH EARLY AFTERNOON. GIVEN THAT SOME OF THE LIFT WILL BE IN THE DGZ AREA ACROSS THE SOUTH DURING THE DAY...WE SHOULD SEE SNOW RATIOS ACROSS THE FAR SOUTHEAST AROUND 15-17:1 DURING THE DAY WHICH WOULD EQUATE TO 3-5 INCHES OF SNOW BY EVENING. MOST LIKELY AN ADVISORY WILL BE NEEDED IN THIS AREA ON SUNDAY...BUT WILL HOLD OFF SINCE THIS WILL BE GENERALLY A 3RD PERIOD ADVY. AS FOR AREAS CLOSER TO LAKE SUPERIOR...ALL OF THE NWP GUIDANCE SHOW PBL WINDS STAYING NELY THROUGH THE DAY WHICH SHOULD ALLOW FOR TERRAIN ENHANCED SNOW TO COMMENCE IN THE NE FLOW FAVORED AREAS DESPITE THE RELATIVELY WEAK SYNOPTIC LIFT. WITH THE BEST LIFT BEING CONFINED TO GENERALLY BELOW THE DGZ...EXPECT SNOW RATIOS BE BE FAIRLY LOW WITH ONLY AROUND 13:1. WILL GENERALLY GO WITH 4 OR 5 INCHES AT MOST IN THESE AREAS...BUT GIVEN THE STRONG AND DEEP NE FLOW...WOULD NOT BE SHOCKED IF QPF AND THUS SNOWFALL IS MORE ON SUNDAY. THEN ON SUNDAY NIGHT...DIFFERENCE START TO DEVELOP WITH THE MODELS REGARDING THE EVOLUTION OF THE NORTHERN STREAM UPPER TROUGH. THE NAM IS CERTAINLY THE MOST AGGRESSIVE IN CLOSING OFF THE LOW AND SETTLING OVER THE UPPER GREAT LAKES...WHICH ALLOW FOR A STRONG INVERTED TROUGH TO HANG BACK ACROSS THE CENTRAL GREAT LAKES THROUGH MONDAY. MEANWHILE...THE GFS GENERALLY KEEPS THE UPPER TROUGH OPEN AND MOVES IN THROUGH THE AREA BY MONDAY AFTERNOON. THE LATEST 00Z ECMWF IS INTERESTING AS IT ALSO ATTEMPT TO CLOSE OFF THE LOW SUN NIGHT BUT IS NOT NEARLY AS DEEP AS THE NAM FORECASTS. NONETHELESS...THE ECMWF ALSO SUGGESTS THAT THERE WILL BE SOME TYPE OF INVERTED TROUGH EXTENDING BACK INTO THE AREA THROUGH MONDAY AND OUR LOCALLY PRODUCE ARW-WRF USING THE GFS AS BOUNDARY CONDITIONS ALSO SUGGEST THAT THERE WILL BE A INVERTED TROUGH HANGING BACK THROUGH MONDAY. AS SUCH...DO NOT THINK THE PBL WINDS WILL SHIFT TO N-NW AS FAST AS THE GFS AND ECMWF SUGGEST. IN FACT...THE CURRENT THINKING IS THAT THE WINDS WILL STAY NORTHERLY OR PERHAPS A LITTLE EAST OF NORTH THROUGH MONDAY WITH THIS TROUGH STAYING SOUTH OF THE AREA. WITH ALL OF THIS SAID...THE EXPECTATION IS THAT THE SNOW WILL TRANSITION TO MORE LAKE ENHANCED VARIETY AND PERSIST RIGHT THROUGH MONDAY BEFORE THE UPPER TROUGH SWINGS THROUGH AND ALLOWS THE WIND TO GRADUALLY SHIFT TO THE N-NW BY MON EVENING. AS SUCH...EXPECT MODERATE TO LOCALLY HEAVY SNOW TO CONTINUE IN MQT/BARAGA COUNTIES AS WELL AS GOGEBIC COUNTY THROUGH THE NIGHT SUNDAY INTO MONDAY. THE BEST LIFT RAPIDLY BECOMING ENTRENCHED IN THE DGZ SUNDAY EVENING AS THE UPPER TEMPS DROP...EXPECT THE SNOW TO BECOME MUCH MORE FLUFFY BUT ALSO ACCUMULATE MUCH FASTER WITH RATIOS CLOSE TO 25:1 BY MON MORNING. SOME AREAS IN THE WATCH AREA COULD SEE ANOTHER 8-12 INCHES OF SNOW SUN NIGHT INTO MONDAY. INTERESTINGLY...THERE ARE SEVERAL VERY GOOD CIPS ANALOG EVENTS FOR THIS SYSTEM. THEY ALL GENERALLY SHOW THE WATCH AREA SEEING SIGNIFICANT 72 HOUR SNOWFALL. NOT SURE IF WE WILL SEE ANY LONGER PERIOD OF HEAVY SNOWFALL...RATHER I AM THINKING THAT IT WILL BE GENERALLY A PERSISTENT SNOWFALL FOR 24-36 HOURS WHICH WILL ALLOW WARNING CRITERIA TO BE REACHED. EVEN MORE INTERESTING...DESPITE THE FACT THAT GOGEBIC COUNTY WILL BE FURTHEST REMOVED FROM THE SYSTEM...THE CURRENT NWP AND ALSO THE CIPS GUIDANCE SUGGEST THAT THIS AREA COULD SEE THE MOST SNOWFALL OUT OF THIS EVENT. WE WILL SEE... ANY REMAINING LES SHOULD END RAPIDLY MON NIGHT/TUE MORNING AS THE HIGH PRES RIDGE BUILDS ACROSS THE FORECAST AREA. STILL LOOKS QUITE COLD TUE MORNING ACROSS THE WEST WITH LIGHT WINDS/CLEAR SKIES. TEMPS 10-20 BELOW NOT OUT OF THE QUESTION IN THE NORMALLY COLDER SPOTS. THE ECMWF AND GEM ARE IN GOOD AGREEMENT IN LIGHT OVERRUNNING/WARM ADVECTION SNOW CHRISTMAS EVE NIGHT INTO CHRISTMAS DAY ACROSS THE ENTIRE FORECAST AREA. SOME HINTS THAT THERE MIGHT BE SOME LAKE ENHANCEMENT OFF OF LAKE MICHIGAN TUESDAY NIGHT AND HAVE OPTED TO CONTINUE LIKELY POPS ACROSS THE EASTERN PART OF THE FORECAST AREA TUE NIGHT INTO CHRISTMAS DAY. SOME DIFFERENCES EMERGE THU INTO FRIDAY REGARDING THE EVOLUTION AND THE TROUGH WITH THE ECMWF BEING DEEPER AND FURTHER SOUTH COMPARED TO THE GFS. REGARDLESS...SENSIBLE WEATHER SHOULD GENERALLY THE SAME WITH EITHER MODEL WITH LES IN THE NW FAVORED SNOWBELTS CHRISTMAS NIGHT INTO THU NIGHT BEFORE DIMINISHING ON FRIDAY AS HIGH PRES BUILDS OVERHEAD. TEMPS STILL LOOK BELOW NORMAL THROUGH THE EXTENDED WITH 850MB TEMPS -20 TO -25C WED NIGHT/THU WARMING TO -15 TO -20C BY FRIDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1229 AM EST SAT DEC 21 2013 WITH ABUNDANT LOW LEVEL MOISTURE AND LIGHT WINDS LINGERING OVER THE REGION...MAINLY MVFR CIGS ARE EXPECTED THROUGH THE FCST PERIOD AT CMX AND IWD. THERE MAY BE A PERIOD OF SNOW SHOWERS AT CMX THAT COULD REDUCE VSBY INTO THE IFR RANGE IF A CONVERGENCE ZONE OVER THE WESTERN LAKE SAGS INTO THE AREA. HOWEVER...CONFIDENCE IN THE TIMING AND PLACEMENT OF THIS FEATURE IS LOW. WEAK DOWNSLOPE WESTERLY FLOW AT SAW WILL FAVOR VFR CONDITIONS UNTIL LATE SAT AFTERNOON WHEN WINDS VEER TO THE NNE AND UPSLOPE FLOW LEADS TO MVFR CIGS AND SOME LIGHT SNOW SHOWERS. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 457 AM EST SAT DEC 21 2013 LIGHT WINDS TODAY WITH TROUGH OVER THE LAKE THEN AS THE TROUGH SINKS SOUTH TONIGHT...EXPECT STRONG AND GUSTY NORTHEAST WINDS TO 30 KTS OVER MUCH OF LAKE SUPERIOR INTO SUNDAY...FURTHER STRENGTHENED BY LOW PRESSURE LIFTING ACROSS LOWER MICHIGAN. COULD BE GALE GUSTS OVER THE WEST WITH CHANNELING BETWEEN MINNESOTA SHORELINE AND KEWEENAW PENINSULA. DURING THIS PERIOD OF STRONGER WINDS THERE WILL BE FREEZING SPRAY. EXPECT THE LOW TO LINGER A SURFACE TROUGH OVER THE UPPER GREAT LAKES THROUGH MONDAY AND KEEP WINDS UP TO 25 KTS. HIGH PRESSURE WILL CROSS THE UPPER GREAT LAKES ON MONDAY NIGHT...WHILE A LOW PRESSURE SYSTEM BEGINS TO TAKE SHAPE IN THE CANADIAN PRAIRIES. THIS LOW WILL LEAD TO INCREASING SOUTHERLY WINDS ACROSS LAKE SUPERIOR ON TUESDAY. WHEN THE LOW MOVES THROUGH THE REGION ON WEDNESDAY...WINDS WILL BECOME WESTERLY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER STORM WATCH FROM SUNDAY MORNING THROUGH MONDAY EVENING FOR MIZ002-004-005-009. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...MRD AVIATION...JLB MARINE...JLA
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
952 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 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 545 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 THE PERIOD. KMSP...MVFR CONDITIONS THROUGH MONDAY IN LIGHT SNOW...WITH VFR CONDITIONS THEREAFTER. 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
NWS DULUTH MN
341 PM CST SAT DEC 21 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 330 PM CST SAT DEC 21 2013 AT 330 PM...IT WAS FAIRLY QUIET ACROSS THE NORTHLAND. THERE CONTINUED TO BE FLURRIES AND ISOLATED SNOW SHOWERS FOR MOST AREAS. THE EXCEPTION WAS ALONG THE NORTH SHORE OF LAKE SUPERIOR...WHERE AN INCH OF SNOW FELL THIS AFTERNOON IN COASTAL LAKE AND COOK COUNTIES. TEMPERATURES RANGED FROM THE SINGLE DIGITS AT INTERNATIONAL FALLS TO THE 20S IN NORTHWESTERN WISCONSIN. THE HIGH RESOLUTION MODEL DATA INDICATES THAT THERE WILL BE PERIODS OF LAKE EFFECT SNOW CONTINUING ACROSS WESTERN LAKE SUPERIOR TONIGHT. THE HRRR AND WRF INDICATE A CONVERGENT BAND OF SNOW ACROSS THE WESTERN PORTION OF THE LAKE...WITH SEVERAL WAVES IN THE LINE. THIS WILL RESULT IN LOCAL SWIRLS AND CONSIDERABLE VARIABILITY TO THE LAKE EFFECT OVERNIGHT. STRONG NORTHEAST WINDS AT ROCK OF AGES CONTINUED ON ONE SIDE OF THIS BAND...WITH GUSTY SOUTHERLY WINDS AT DEVILS ISLAND ON THE OTHER SIDE. WINDS WILL OVERWHELMINGLY BECOME NORTHEAST TO NORTH OVERNIGHT AND ON SUNDAY...WHILE THE OTHER SYSTEM MOVES IN FROM THE WEST. THE RESULT WILL BE A PHASING OF THE MOISTURE ACROSS THE WESTERN GREAT LAKES. OVERALL LOOKING FOR AN INCH OR TWO FOR MUCH OF THE AREA TONIGHT...AND ANOTHER INCH OR TWO ON SUNDAY. THE EXCEPTION WILL BE ACROSS THE SOUTH SHORE OF LAKE SUPERIOR. WE COULD HAVE HANDLED THIS EVENT IN A COUPLE WAYS REGARDING HEADLINES BUT AFTER EXTENSIVE DISCUSSION...WE DECIDED TO ISSUE A LAKE EFFECT SNOW ADVISORY FOR THE PERIOD TONIGHT THROUGH MONDAY...RATHER THAN HAVING A LARGE LAKE EFFECT SNOW WARNING OUT FOR 5 PERIODS...WITH GENERALLY ADVISORY TYPE SNOW FOR MOST OF THE PERIODS. THINK THERE IS A FAIR CHANCE WE MAY NEED TO UPGRADE TO A WARNING FOR MONDAY. BUT FOR TONIGHT AND SUNDAY...WE ARE LOOKING AT TRANSITIONAL LAKE EFFECT SNOWFALL BANDS...SWIRLS AND CONVERGENCE BANDS...AND THE RESULT SHOULD BE WIDESPREAD ADVISORY TYPE SNOW. WE ALSO COULD HAVE ISSUED THE ADVISORY FOR TONIGHT THROUGH SUNDAY NIGHT...AND MAINTAINED THE WATCH FOR MONDAY...BUT FOR SIMPLICITY SAKE...DECIDED TO HOLD OFF ON THAT FOR NOW. THE MAIN FOCUS FOR A POTENTIAL WARNING ON MONDAY WOULD BE THE GOGEBIC RANGE. WE DO AGREE THAT ADDED UP OVER 4-5 PERIODS...THE AMOUNTS COULD BE IMPRESSIVE...SOME ON THE ORDER OF A FOOT OR MORE IN THE GOGEBIC RANGE. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 345 PM CST SAT DEC 21 2013 FIRST CONCERN IN EXTENDED IS ON LONG DURATION LAKE EFFECT SNOW THAT WILL PERSIST THROUGH MONDAY EVENING. THE 12Z RUNS OF THE GFS/ECM/NAM ARE IN AGREEMENT THAT THE H85-H50 TROUGH AXIS PASSES OVER WRN LAKE SUPERIOR DURING THE DAY MONDAY...BRINGING A STRONG PUSH OF CAA WITH H85 TEMPS FALLING INTO THE NEGATIVE 20S AND BOUNDARY LAYER WINDS BACKING OUT OF THE NORTH THEN NORTHWEST. ALTHOUGH CONDITIONS REMAIN FAVORABLE FOR A FEW INCHES OF LIGHT SNOW ALONG THE SOUTH SHORE OF LAKE SUPERIOR SUN NIGHT...LAPSE RATES/INVERSION HTS SIGNIFICANTLY INCREASE MONDAY DUE TO THE ARRIVAL OF THE COLD AIR. HAVE INCREASED QPF/SN AMOUNTS MONDAY TO ACCOUNT FOR THE HIGHER INSTABILITY. FOCUS TURNS TO ELONGATED VORT MAX THAT DROPS OUT OF CANADA AND ACROSS THE NRN PLAINS TUESDAY/WEDNESDAY. LATEST ECM/GFS BOTH SUGGEST THE DIGGING WAVE...WITH SFC REFLECTION COLD FRONT...SWEEPS ACROSS THE NORTHLAND DURING THE CHRISTMAS HOLIDAY. CURRENT TIMING WOULD FAVOR A FEW INCHES OF SNOW OVER MUCH OF THE REGION TUESDAY NIGHT. HOWEVER...IF TIMING SLOWS...ITS POSSIBLE THE COLD FRONT/LIGHT SNOW HOLD OFF UNTIL CHRISTMAS DAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1230 PM CST SAT DEC 21 2013 MAINLY MVFR CEILINGS AND LIGHT FLURRIES WILL BE FOUND TODAY WITH POCKETS OF CLEARING. MVFR CEILINGS WILL AGAIN INCREASE IN COVERAGE OVERNIGHT AS LIGHT SNOW DEVELOPS ACROSS THE AREA SUNDAY MORNING. && .PRELIMINARY POINT TEMPS/POPS... DLH 8 13 -8 1 / 70 90 70 20 INL -9 2 -20 -5 / 40 50 20 10 BRD 4 11 -13 -2 / 70 90 50 10 HYR 11 21 1 6 / 60 90 80 70 ASX 15 21 9 9 / 70 90 90 80 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...LAKE EFFECT SNOW ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST MONDAY FOR WIZ001>004. LS...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 4 AM CST MONDAY FOR LSZ121-140>148. && $$ SHORT TERM...DAP LONG TERM...GRANING AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1154 AM CST Sat Dec 21 2013 .UPDATE... Issued at 1152 AM CST SAT DEC 21 2013 No significant changes have been made to the forecast thinking. The past few hours have seen a relative lull in precipitation, however freezing rain and sleet appears to be rapidly filling back in across eastern KS and western MO in an area of increasing isentropic ascent. Precipitation will likely continue to expand through mid afternoon across areas near and south of the Highway 36 corridor. Thermal profiles suggest most of this precip will take the form of sleet or a sleet/freezing rain mix along and north of a Kansas City to Macon line, with mostly freezing rain to the south. Could see additional ice accumulations around a tenth of an inch for the Butler/Sedalia/Boonville areas through sunset with local amounts up to two tenths of an inch. Further north across the KC to Moberly corridor there will likely be a thin glazing of ice with minor (1/4" or less) accumulations of sleet. Higher threat for icing will be south of the Missouri River with more sleet to the north. Later tonight all models continue to point to several inches of accumulating snow occurring from the KC and STJ areas northeast toward Kirksville. The NAM in particular is supportive of a frontogenetical band of heavy snow developing somewhere between Kansas City and St. Joseph that could provide enhanced snowfall rates up to 2" per hour and possibly thunder. However other models including the RAP are less suggestive of this and differ substantially with where such a band would set up. For now no major changes are being made to snow totals tonight, with a band of 5"+ snows setting up near and just north of the KC/Kirksville corridor. If frontogenetical forcing does begin to dominate later this evening, then there could be some enhanced snow amounts around 8" somewhere near St. Joseph or Kansas City with a sharper gradient between areas that receive heavy snow and areas that see little snowfall. && .SHORT TERM...(Today through Sunday Night) Issued at 353 AM CST SAT DEC 21 2013 Early morning water vapor imagery shows an impressive plume of Pacific moisture spreading across the central CONUS ahead of a deep upper trough centered over the northern Chihuahua state of Mexico. Precipitation has broken out in earnest since mid afternoon from Oklahoma into the Ozarks, and the anticipated northward shift of this moisture and the arrival of the upper low tonight remain the primary forecast concerns through the next 24 hours. TODAY ------ IMPACTS: Minor ice accumulations generally along and south of a Kansas City to Moberly line -- highest mid Missouri southward. Regional radar imagery mimics the inherited forecast rather well. As expected, precipitation has had difficulties gaining latitude north of I-44, owing to persistent warm advection from eastern OK into nrn AR along the nose of a 60+ knot low level jet, yielding a broken arc of thunderstorms and substantial trailing stratiform region from central OK into srn MO. Meanwhile, isentropic downglide continues to erode at northward precipitation advances, with a considerable dry layer still present between the low stratus and the Pacific moist plume aloft. A few pockets of freezing rain have reached the far srn CWA (Clinton-Sedalia-Boonville) early this morning, but impacts have been minimal. We`ve also received some sleet reports which were puzzling given the +6 to +8C warm nose aloft at 800mb, but a more in-depth look at soundings shows that 925mb temps bottom at -8 to -10C, enough to refreeze some of those rain drops. That cold layer is expected to moderate some this morning, keeping most of the precip as FZRA. Although low level flow trajectories are currently from the SW, keeping most of the precip over OK/AR/srn MO, I anticipate that the flow will back this morning as the upper trough begins to lift across the TX/MX border and become negative tilt. This , coupled with increasing large scale ascent, should allow a net northward transport of the steadier precipitation into the forecast area before daybreak and continuing throughout the day. Heavier precipitation should remain focused just southeast of the CWA border from Springfield-Columbia-St. Louis and points south. Travel down toward the I-44 corridor is *highly* discouraged. Locally, freezing rain (possibly mixed sleet north and west) will result in minor ice accretion of a few hundredths to around a tenth of an inch, with the exception of Clinton-Sedalia-Boonville where up to a third of an inch of icing is possible. Maintenance of northerly low level ageostrophic flow should keep temperatures below freezing throughout the day. TONIGHT: -------- IMPACTS: Light icing will diminish eastern areas this evening. Rapid snow accumulations become the main concern across portions of northwest and north central Missouri from sundown through 6 AM. Once again, the forecast is anything but a slam dunk with a rather sharp snow gradient anticipated across the CWA. Conveying this message to partners and customers may be more challenging than the forecast itself, as there will likely be close proximity between the haves and have nots when all is said and done. As the upper low matures on its approach early this evening, column saturation will occur quickly over NW MO with temperature profiles rapidly cooling below freezing. Models remain consistent with taking the core of the mid level center across Kansas City to Kirksville between 06 and 09Z, with deformation of the mid level frontal zone yielding rather prolific snowfall rates in a 100 mile zone northwest of the center track. Despite the fast system speed and an increasingly disconnected warm conveyor source region, cross-sections show vigorous ascent (30+ ubar/s) associated with strong mid-level frontogenesis within the optimal -12 to -18C dendritic growth region. This should yield a quick 4 to 7" snowfall in meso-alpha scale band. While the placement of highest snow accumulations and amounts have not changed, the forecast gets rather dicey east of a Kansas City to Kirksville line. Although not well handled in most of the model output, it would seem to reason that narrow dry slot would develop given a system of this strength/maturity, and punch east of the mid level low center during the evening as the cyclone reaches maturity. If this occurs, snowfall accumulations over the eastern CWA may be significantly reduced if not eliminated as ice nuclei are scoured. Even a slight shift in the cyclone track could mean the difference between a location receiving plowable snows and potentially a non- event. This gradient may perhaps exist across the KC metro itself, so we will need to remain focused on this message until the deformation zone becomes clear by late afternoon to our SW. The upper low should continue to accelerate NE after midnight, and most of the accumulating snowfall will shift north of the Iowa border by 12Z. The next shift may want to consider trimming the winter storm warning end time back to around 12Z. SUNDAY/SUNDAY NIGHT: -------------------- IMPACTS: Bitter cold. Cloudy and somewhat blustery conditions expected. Temperatures will barely reach the mid 20s, with wind chills in the teens. With the passage of the longwave mid level trough axis Sunday evening, low level flow will turn anti-cyclonic. The leading edge of stronger gradient flow, associated with a surge of low level arctic air, will push into the CWA by early evening as skies gradually clear. Some areas could see the coldest lows of the season given the magnitude of this airmass coupled with fresh snow cover. Bookbinder .LONG TERM...(Monday through Friday) Issued at 353 AM CST SAT DEC 21 2013 Beginning of the work week continues to look cold as the large scale trough that helped bring the weekends winter weather will still be in place across the Plains States. This will allow a surge of cold air to spread across the central Plains Sunday night through Monday night. Advertisements from the models indicate the 850mb temperatures in the -10C to -15C range will move south with a 1037mb surface high. This will keep temperatures in the teens --if not colder-- for Monday`s high with early morning lows Tuesday ranging below zero in all areas north of the Missouri River. Given the current forecast, any light wind Tuesday morning will result in dangerously cold wind chill values. However, later Tuesday the center of the cold surface high will slide to our east, moderating our temperatures as we move forward through the week. This should allow temperatures to creep back into the 20s and 30s for Christmas day. A few of the medium range models indicate that another shortwave trough swinging through the northern Plains into the Great Lakes may induce a bit of light precipitation on the back side of the exiting surface high Wednesday, but confidence is rather low on this potential. && .AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon) Issued at 1152 AM CST SAT DEC 21 2013 Sleet with some freezing rain mixed in has developed near MCI with additional activity filling in upstream toward ICT. There will likely be some breaks in this activity before it becomes more widespread toward 21Z, but impacts are significant enough to just carry prevailing FZRAIP through the afternoon. Increasing activity toward 21Z could lead to a thin glazing of ice and/or minor sleet accumulations for MKC/MCI while STJ/IRK are more likely to see sleet and some snow. Mixed precipitation will change to all snow toward 00Z for STJ/MCI and closer to 03Z for IRK/DMO areas. MCI-IRK corridor has the potential to see heavy snow with visibilities approaching or exceeding airport minimums and snowfall rates exceeding 1" per hour. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...WINTER STORM WARNING until Noon CST Sunday FOR KSZ057-060-105. WINTER STORM WARNING until Noon CST Sunday FOR KSZ025-102>104. MO...WINTER STORM WARNING until Noon CST Sunday FOR MOZ032-033- 037>040-043>046-053-054. WINTER STORM WARNING until Noon CST Sunday FOR MOZ001>008- 011>017-020>025-028>031. && $$ UPDATE...Hawblitzel SHORT TERM...Bookbinder LONG TERM...Cutter AVIATION...Hawblitzel
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1022 AM EST SAT DEC 21 2013 .SYNOPSIS...WARM SOUTHERLY FLOW AROUND BERMUDA HIGH PRESSURE WILL CONTINUE THIS WEEKEND...AHEAD OF A MOISTURE-LADEN COLD FRONT THAT WILL CROSS OUR REGION SUNDAY NIGHT AND MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1020 AM SATURDAY... TODAY: A WARM/MILD DAY IS EXPECTED TODAY ACROSS CENTRAL NC... WITH HIGH PRESSURE AT THE SURFACE AND ALOFT REMAINING ANCHORED OFF THE SOUTHEAST U.S. COAST. THIS WILL RESULT IN A CONTINUED WARM/MOISTENING DEEP SOUTH TO SOUTHWESTERLY RETURN FLOW ACROSS OUR AREA. LOW LEVEL FLOW IS EXPECTED TO STRENGTHEN TODAY AS A POTENT S/W LIFTS NORTHEASTWARD INTO THE SOUTHERN PLAINS OUT OF WEST TEXAS. THE MAIN LOW LEVEL JET IS EXPECTED TO REMAIN TO THE WEST OF THE AREA TODAY... WITH THE THE SURFACE FRONT EXPECTED TO SLOWLY SHIFT EASTWARD ACROSS THE OHIO RIVER VALLEY AND ARK-LA-TEX REGIONS TODAY. THUS... THINK THE BULK OF ANY LIGHT SHOWER ACTIVITY WILL GENERALLY REMAIN JUST TO THE WEST OF OUR AREA TODAY. THE BIG QUESTIONS THAT REMAIN... IS HOW MUCH CLOUD COVER WE WILL HAVE TODAY AND THE IMPACTS ON HIGH TEMPS. THE LATEST GFS AND RAP ARE MORE AGGRESSIVE THAN THE NAM WRT TO LOW LEVEL CLOUD COVER TODAY... ESPECIALLY ACROSS OUR WESTERN REACHES. IN ADDITION... ALL MODEL GUIDANCE CONDITIONS TO SHOW MID AND HIGH LEVEL CLOUD COVER STREAMING ACROSS THE REGION TODAY... AT TIMES THICKER... AS WEAK EMBEDDED IMPULSES MOVE THROUGH THE SOUTHWESTERLY FLOW ALOFT. FOR NOW WILL TREND THE FORECAST A LITTLE BIT MORE TOWARDS THE GFS/RAP (WHICH IS A GOOD BLEND BETWEEN THE GUIDANCE) GIVEN THE EXPECTED STRENGTHENING OF THE LOW LEVEL FLOW AND QUITE A BIT OF LOW LEVEL CLOUD COVER TO THE SOUTH-SOUTHWEST OF THE REGION CURRENTLY (ACROSS THE UPSTATE OF SC). GIVEN THIS... WILL TRIM HIGHS BACK BY A DEGREE OR TWO ACROSS THE WESTERN HALF OF THE AREA. STILL THESE HIGHS WILL BE NEAR OR ABOVE RECORD VALUES FOR TODAY. EXPECT HIGHS TEMPS WILL RANGE FROM THE UPPER 60S NEAR 70 NW TO THE UPPER 70S SE. -77 TONIGHT: SKIES WILL LIKELY LARGELY CLEAR FOR A TIME THIS EVENING AND EARLY TONIGHT...AS THE FLOW ALOFT BACKS IN RESPONSE TO THE APPROACH OF THE DEAMPLIFYING UPPER LOW FROM WEST TX...AND FURTHER RIDGE AMPLIFICATION OVER THE CARIBBEAN...AND CONSEQUENTLY BOWS THE MID- HIGH CLOUDINESS NORTHWESTWARD TOWARD THE APPALACHIANS. THIS WILL SET THE STAGE FOR A HIGHER-THAN-PREVIOUS-DAYS PROBABILITY AND COVERAGE OF STRATUS OVERNIGHT...AMIDST A STEADILY STRENGTHENING WAA REGIME. THIS PATTERN ALSO SUPPORTS THE INHERITED CHANCE OF SHOWERS OVER THE WESTERN PIEDMONT...WHOSE DEPTH WILL BE LIMITED BY A CAPPING INVERSION ALOFT PER BUFR FORECAST SOUNDINGS...AND A LACK OF MORE APPRECIABLE LOW LEVEL MOISTURE AND RELATED INSTABILITY. MILD WITH LOWS IN THE LOWER TO MIDDLE 60S - ALSO AROUND RECORD HIGH MINS FOR THE DATE. -26 && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 305 AM SATURDAY... DEEP SOUTHWESTERLY FLOW AHEAD OF AN APPROACHING COLD FRONT WILL TAP INTO GULF MOISTURE... BRINGING PWS OF OVER 1.5 INCHES TO THE AREA SUNDAY... NEAR MAX VALUES RECORDED FOR DECEMBER. HEAVY RAINFALL WILL BE A POTENTIAL CONCERN... MAINLY OVER URBAN AREAS AS QPF REMAINS SHORT OF FLASH FLOOD GUIDANCE AT THIS TIME. MID LEVEL LAPSE RATES REMAIN WEAK... AND INSTABILITY LOW... SO THE SEVERE THREAT REMAINS NEGLIGIBLE. ANY STORMS THAT DO DEVELOP MAY TAP IN TO THE STRONG 60- 65 KT LLJ AND BRING THE POTENTIAL FOR STRONG GUSTY WINDS ALONG WITH HEAVY RAINFALL. SHEAR PROFILES WOULD BE SUPPORTIVE OF ROTATION... HOWEVER THIS GOES STRONGLY AGAINST CLIMATOLOGY AND WITH THE AFOREMENTIONED ENVIRONMENT... THIS IS A VERY LOW END THREAT. NEAR RECORD HIGHS IN THE 70S. THE COLD FRONT CROSSES THE AREA MONDAY AFTERNOON... MAKING IT TO THE CAROLINA COAST BY 03Z TUES. HIGHS IN THE 60S. SHOWERS WILL END FROM WEST TO EAST DURING THE EVENING HOURS. LOWS IN THE 30S WITH STRONG COLD ADVECTION. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 307 AM SATURDAY... UPPER LEVEL TROUGH MOVES OFF THE EAST COAST ON TUESDAY... AND THE COLUMN DRIES SIGNIFICANTLY AS UPPER LEVEL FLOW BECOMES WESTERLY. HIGH PRESSURE OVER THE MISSISSIPPI VALLEY ON TUESDAY WILL BUILD OVER THE EAST COAST WEDNESDAY. HIGHS IN THE 40S ON TUESDAY AND WEDNESDAY WILL MODERATE TOWARD NORMAL... IN THE 50S... THURSDAY THROUGH FRIDAY. AN UPPER LEVEL TROUGH OVER CENTRAL US ON THURSDAY WILL MOVE EASTWARD THROUGH THE END OF THE PERIOD... WITH DIFFERENCES ARISING FROM SHORTWAVES MOVING THROUGH THE FLOW DURING THIS TIME. WILL INTRODUCE SLIGHT CHANCE POPS FOR FRIDAY. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 750 AM SATURDAY... GENERALLY VFR CONDITIONS EARLY THIS MORNING...ASIDE FROM VISIBILITY RESTRICTIONS IN FOG AT KFAY...WILL LIKELY TRANSITION THROUGH A FEW HOUR PERIOD OF MVFR/IFR CEILINGS BETWEEN 13-16Z AT ALL BUT THE TRIAD TERMINALS...AS DIURNAL HEATING ACTS UPON AN INCREASINGLY MOIST AIR MASS NEAR THE SURFACE. CONFIDENCE OF THIS SUB-VFR OCCURRENCE IS ABOUT 50 PERCENT...AND MOST LIKELY AT KFAY. VFR CONDITIONS WITH A BREEZY SSW WIND WILL OTHERWISE PREVAIL THROUGH THE THIS EVENING...BEFORE WIDESPREAD LIFR/VLIFR STRATUS DEVELOPS BETWEEN 03- 07Z TONIGHT. A LITTLE PATCHY DRIZZLE MAY ALSO ACCOMPANY THE STRATUS. LOOKING AHEAD: SHOWERS WILL BECOME NUMEROUS ACROSS THE AREA FROM WEST TO EAST SUNDAY INTO SUNDAY NIGHT WITH WIDESPREAD SUB-VFR CONDITIONS IN RAIN...POSSIBLY HEAVY AT TIMES...CONTINUING THROUGH MONDAY AFTERNOON...AS A SLOW MOVING COLD FRONT PUSHES EAST THROUGH THE AREA. VFR CONDITIONS ARE EXPECTED TO RETURN BY TUESDAY AND CONTINUE THROUGH THE REMAINDER OF THE PERIOD. && .CLIMATE... AS OF 230 PM WEDNESDAY... DAILY RECORDS FOR SATURDAY/SUNDAY DECEMBER 21/22 ARE AS FOLLOWS: RALEIGH/DURHAM... HIGHHI MIN DECEMBER 21... 71 DEGREES...SET IN 196759 DEGREES...SET IN 1923 DECEMBER 22... 75 DEGREES...SET IN 196761 DEGREES...SET IN 2011 -------------------------------------------------------------------- GREENSBORO... HIGHHI MIN DECEMBER 21... 66 DEGREES...SET IN 192355 DEGREES...SET IN 1984 DECEMBER 22... 71 DEGREES...SET IN 192360 DEGREES...SET IN 2011 -------------------------------------------------------------------- FAYETTEVILLE... HIGHHI MIN DECEMBER 21... 77 DEGREES...SET IN 193160 DEGREES...SET IN 1923 DECEMBER 22... 75 DEGREES...SET IN 201160 DEGREES...SET IN 2011 && .RAH WATCHES/WARNINGS/ADVISORIES... NONE && $$ SYNOPSIS...26 NEAR TERM...77/26 SHORT TERM...30 LONG TERM...30 AVIATION...26/CBL CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
309 AM EST SAT DEC 21 2013 .SYNOPSIS...WARM SOUTHERLY FLOW AROUND BERMUDA HIGH PRESSURE WILL CONTINUE THIS WEEKEND...AHEAD OF A MOISTURE-LADEN COLD FRONT THAT WILL CROSS OUR REGION SUNDAY NIGHT AND MONDAY. && .NEAR TERM /THROUGH SATURDAY NIGHT/... AS OF 930 PM FRIDAY... HIGH PRESSURE REMAINS ANCHORED OFF THE CAROLINA COAST THIS EVENING. CIRRUS CONTINUES TO STREAM ACROSS THE AREA FROM THE SOUTHWEST AS SOUTHWESTERLY UPPER LEVEL FLOW STRENGTHENS AHEAD OF A VIGOROUS STORM SYSTEM TAKING SHAPE ACROSS THE SOUTHERN US. BASED ON SATELLITE TRENDS...CIRRUS MAY THIN AT TIMES BUT A MAJORITY OF THE NIGHT WILL BE MOSTLY CLOUDY. RETURN FLOW AROUND THE SURFACE HIGH MAKES STRATUS A POSSIBILITY ONCE AGAIN...THOUGH FORECAST SOUNDINGS ARE NOT SUGGESTING WIDESPREAD STRATUS DEVELOPMENT. THE 00Z RAOBS SHOW QUITE A BIT MORE LOW-LEVEL MOISTURE AT KFFC THAN AT KCHS...WHICH IS WHERE THE LOW-LEVEL FLOW IS ORIGINATING THIS EVENING. THE HRRR IS THE MAIN MODEL SHOWING BETTER COVERAGE DEVELOPING OVER SC LATE TONIGHT AND SPREADING ACROSS CENTRAL NC THROUGH MID-MORNING...BUT GIVEN THE AMOUNT OF HIGH CLOUDS AND LACK OF MODEL AGREEMENT..EXPECT STRATUS WILL BE PATCHY AND LATE TO DEVELOP. REGARDING TEMPS...CIRRUS HAS HINDERED COOLING ALREADY THIS EVENING...AND UNLESS BETTER BREAKS IN THE CIRRUS DEVELOP...LOWS WILL STRUGGLE TO FALL MUCH FURTHER THAN THE UPPER 40S AND LOWER 50S IN MOST AREAS. -SMITH SATURDAY AND SATURDAY NIGHT: THE AFOREMENTIONED COLD FRONT WILL CONTINUE TO SLOWLY APPROACH THE REGION FROM THE WEST AS A SURFACE WAVE OF LOW PRESSURE LIFTS FROM EASTERN TX INTO THE OHIO VALLEY ALONG THE FRONT. WHILE LOW LEVEL CLOUD COVER SHOULD BE GREATER THAN TODAY... AFTERNOON LOW LEVEL THICKNESS VALUES WILL INCREASE INTO THE 1380S ON SATURDAY AFTERNOON... SOME 20 METERS HIGHER THAN TODAY. THIS SHOULD YIELD HIGH TEMPS NEAR STATISTICAL GUIDANCE (NEAR THE WARM SIDE OF GUIDANCE)... AROUND 70 NW TO THE MID 70S EAST/SOUTHEAST. LOWS WILL BE VERY WARM FOR THIS TIME OF YEAR WITH AGAIN POSSIBLY SOME LOW CLOUDS. EXPECT LOWS WILL BE AROUND 60. BOTH HIGHS AND LOWS WILL BE NEAR RECORD VALUES (RECORD HIGH MAX AND RECORD HIGH MIN). SEE CLIMATE SECTION BELOW. WE COULD SEE SOME PRE- FRONTAL SHOWERS AS INCREASING LOW LEVEL FLOW MAY HELP SUPPORT SOME LIGHT SHOWERS ACROSS POINTS FROM OUR WESTERN PIEDMONT WESTWARD LATE SATURDAY AFTERNOON INTO SATURDAY NIGHT. IF WE DO INDEED SEE ANY PRECIP... EXPECT THE SHOWERS SHOULD BE LIGHT AND SPOTTY. FOR NOW WILL KEEP POPS LOW FOR THIS TIME FRAME ACROSS THE WESTERN PIEDMONT... AND NO POPS ELSEWHERE. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 305 AM SATURDAY... DEEP SOUTHWESTERLY FLOW AHEAD OF AN APPROACHING COLD FRONT WILL TAP INTO GULF MOISTURE... BRINGING PWS OF OVER 1.5 INCHES TO THE AREA SUNDAY... NEAR MAX VALUES RECORDED FOR DECEMBER. HEAVY RAINFALL WILL BE A POTENTIAL CONCERN... MAINLY OVER URBAN AREAS AS QPF REMAINS SHORT OF FLASH FLOOD GUIDANCE AT THIS TIME. MID LEVEL LAPSE RATES REMAIN WEAK... AND INSTABILITY LOW... SO THE SEVERE THREAT REMAINS NEGLIGIBLE. ANY STORMS THAT DO DEVELOP MAY TAP IN TO THE STRONG 60- 65 KT LLJ AND BRING THE POTENTIAL FOR STRONG GUSTY WINDS ALONG WITH HEAVY RAINFALL. SHEAR PROFILES WOULD BE SUPPORTIVE OF ROTATION... HOWEVER THIS GOES STRONGLY AGAINST CLIMATOLOGY AND WITH THE AFOREMENTIONED ENVIRONMENT... THIS IS A VERY LOW END THREAT. NEAR RECORD HIGHS IN THE 70S. THE COLD FRONT CROSSES THE AREA MONDAY AFTERNOON... MAKING IT TO THE CAROLINA COAST BY 03Z TUES. HIGHS IN THE 60S. SHOWERS WILL END FROM WEST TO EAST DURING THE EVENING HOURS. LOWS IN THE 30S WITH STRONG COLD ADVECTION. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 307 AM SATURDAY... UPPER LEVEL TROUGH MOVES OFF THE EAST COAST ON TUESDAY... AND THE COLUMN DRIES SIGNIFICANTLY AS UPPER LEVEL FLOW BECOMES WESTERLY. HIGH PRESSURE OVER THE MISSISSIPPI VALLEY ON TUESDAY WILL BUILD OVER THE EAST COAST WEDNESDAY. HIGHS IN THE 40S ON TUESDAY WILL MODERATE TOWARD NORMAL... IN THE 50S... WEDNESDAY THROUGH FRIDAY. AN UPPER LEVEL TROUGH OVER CENTRAL US ON THURSDAY WILL MOVE EASTWARD THROUGH THE END OF THE PERIOD... WITH DIFFERENCES ARISING FROM SHORTWAVES MOVING THROUGH THE FLOW DURING THIS TIME. WILL INTRODUCE SLIGHT CHANCE POPS FOR FRIDAY. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 128 AM SATURDAY... VFR CONDITIONS EARLY THIS MORNING MAY TRANSITION TO A PERIOD OF MVFR/LIFR CEILINGS BETWEEN 11-16Z...AS DIURNAL HEATING ACTS UPON AN INCREASINGLY MOIST AIR MASS NEAR THE SURFACE. CONFIDENCE OF THIS SUB- VFR OCCURRENCE IS ABOUT 50 PERCENT...AND MOST LIKELY AT KFAY/ KRDU/KGSO. VFR CONDITIONS WITH A BREEZY SSW WIND WILL OTHERWISE PREVAIL THROUGH THE TAF PERIOD. LOOKING AHEAD: THE PROBABILITY OF LOW CLOUDS/STRATUS SHOULD CONTINUE TO INCREASE SATURDAY NIGHT/SUNDAY MORNING WITHIN STRENGTHENING MOISTURE TRANSPORT FEED FROM THE GULF...COMPLIMENTS OF A 50KT LLJ. SHOWERS WILL BECOME MORE NUMEROUS ACROSS THE AREA FROM WEST TO EAST LATE SUNDAY AFTERNOON AND INTO SUNDAY NIGHT WITH WIDESPREAD SUB-VFR CONDITIONS IN RAIN...POSSIBLY HEAVY AT TIMES...CONTINUING THROUGH MONDAY EVENING AS A SLOW MOVING COLD FRONT PUSHES EAST THROUGH THE AREA. VFR CONDITIONS ARE EXPECTED TO RETURN BY TUESDAY AND CONTINUE THROUGH THE REMAINDER OF THE PERIOD. && .CLIMATE... AS OF 230 PM WEDNESDAY... DAILY RECORDS FOR SATURDAY/SUNDAY DECEMBER 21/22 ARE AS FOLLOWS: RALEIGH/DURHAM... HIGHHI MIN DECEMBER 21... 71 DEGREES...SET IN 196759 DEGREES...SET IN 1923 DECEMBER 22... 75 DEGREES...SET IN 196761 DEGREES...SET IN 2011 -------------------------------------------------------------------- GREENSBORO... HIGHHI MIN DECEMBER 21... 66 DEGREES...SET IN 192355 DEGREES...SET IN 1984 DECEMBER 22... 71 DEGREES...SET IN 192360 DEGREES...SET IN 2011 -------------------------------------------------------------------- FAYETTEVILLE... HIGHHI MIN DECEMBER 21... 77 DEGREES...SET IN 193160 DEGREES...SET IN 1923 DECEMBER 22... 75 DEGREES...SET IN 201160 DEGREES...SET IN 2011 && .RAH WATCHES/WARNINGS/ADVISORIES... NONE && $$ SYNOPSIS...26 NEAR TERM...77/SMITH SHORT TERM...30 LONG TERM...30 AVIATION...26/CBL CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
128 AM EST SAT DEC 21 2013 .SYNOPSIS...WARM SOUTHERLY FLOW AROUND BERMUDA HIGH PRESSURE WILL CONTINUE THIS WEEKEND...AHEAD OF A MOISTURE-LADEN COLD FRONT THAT WILL CROSS OUR REGION SUNDAY NIGHT AND MONDAY. && .NEAR TERM /THROUGH SATURDAY NIGHT/... AS OF 930 PM FRIDAY... HIGH PRESSURE REMAINS ANCHORED OFF THE CAROLINA COAST THIS EVENING. CIRRUS CONTINUES TO STREAM ACROSS THE AREA FROM THE SOUTHWEST AS SOUTHWESTERLY UPPER LEVEL FLOW STRENGTHENS AHEAD OF A VIGOROUS STORM SYSTEM TAKING SHAPE ACROSS THE SOUTHERN US. BASED ON SATELLITE TRENDS...CIRRUS MAY THIN AT TIMES BUT A MAJORITY OF THE NIGHT WILL BE MOSTLY CLOUDY. RETURN FLOW AROUND THE SURFACE HIGH MAKES STRATUS A POSSIBILITY ONCE AGAIN...THOUGH FORECAST SOUNDINGS ARE NOT SUGGESTING WIDESPREAD STRATUS DEVELOPMENT. THE 00Z RAOBS SHOW QUITE A BIT MORE LOW-LEVEL MOISTURE AT KFFC THAN AT KCHS...WHICH IS WHERE THE LOW-LEVEL FLOW IS ORIGINATING THIS EVENING. THE HRRR IS THE MAIN MODEL SHOWING BETTER COVERAGE DEVELOPING OVER SC LATE TONIGHT AND SPREADING ACROSS CENTRAL NC THROUGH MID-MORNING...BUT GIVEN THE AMOUNT OF HIGH CLOUDS AND LACK OF MODEL AGREEMENT..EXPECT STRATUS WILL BE PATCHY AND LATE TO DEVELOP. REGARDING TEMPS...CIRRUS HAS HINDERED COOLING ALREADY THIS EVENING...AND UNLESS BETTER BREAKS IN THE CIRRUS DEVELOP...LOWS WILL STRUGGLE TO FALL MUCH FURTHER THAN THE UPPER 40S AND LOWER 50S IN MOST AREAS. -SMITH SATURDAY AND SATURDAY NIGHT: THE AFOREMENTIONED COLD FRONT WILL CONTINUE TO SLOWLY APPROACH THE REGION FROM THE WEST AS A SURFACE WAVE OF LOW PRESSURE LIFTS FROM EASTERN TX INTO THE OHIO VALLEY ALONG THE FRONT. WHILE LOW LEVEL CLOUD COVER SHOULD BE GREATER THAN TODAY... AFTERNOON LOW LEVEL THICKNESS VALUES WILL INCREASE INTO THE 1380S ON SATURDAY AFTERNOON... SOME 20 METERS HIGHER THAN TODAY. THIS SHOULD YIELD HIGH TEMPS NEAR STATISTICAL GUIDANCE (NEAR THE WARM SIDE OF GUIDANCE)... AROUND 70 NW TO THE MID 70S EAST/SOUTHEAST. LOWS WILL BE VERY WARM FOR THIS TIME OF YEAR WITH AGAIN POSSIBLY SOME LOW CLOUDS. EXPECT LOWS WILL BE AROUND 60. BOTH HIGHS AND LOWS WILL BE NEAR RECORD VALUES (RECORD HIGH MAX AND RECORD HIGH MIN). SEE CLIMATE SECTION BELOW. WE COULD SEE SOME PRE- FRONTAL SHOWERS AS INCREASING LOW LEVEL FLOW MAY HELP SUPPORT SOME LIGHT SHOWERS ACROSS POINTS FROM OUR WESTERN PIEDMONT WESTWARD LATE SATURDAY AFTERNOON INTO SATURDAY NIGHT. IF WE DO INDEED SEE ANY PRECIP... EXPECT THE SHOWERS SHOULD BE LIGHT AND SPOTTY. FOR NOW WILL KEEP POPS LOW FOR THIS TIME FRAME ACROSS THE WESTERN PIEDMONT... AND NO POPS ELSEWHERE. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 250 PM FRIDAY... STRONG WARM AIR ADVECTION CONTINUES AHEAD OF THE SLOWLY APPROACHING COLD FRONT...WITH RECORD HIGH TEMPERATURES ON SUNDAY. SHOWER ACTIVITY WILL BE GRADUALLY SPREADING INTO THE WESTERN PIEDMONT THROUGH THE DAY...WITH CHANCE POPS IN THE EAST BY EVENING. STRENGTHENING IN THE LOW LEVEL JET (>50KTS) AND FAVORABLE UPPER DIFFLUENCE WILL BE OFFSET BY MEAGER INSTABILITY...WITH NEAR NEGLIGIBLE CAPE SUNDAY...WILL CONTINUE ONGOING ISOLATED THUNDER. HIGHS WILL REACH MID TO UPPER 70S OVER MOST OF THE AREA. LIKELY TO CATEGORICAL POPS WILL BE THE RULE SUNDAY NIGHT AND MONDAY AS THE FRONT MOVES SLOWLY ACROSS THE AREA. SIMILARLY...FORCING IS STRONG IN THE FRONTAL ZONE...OFFSET BY WEAK MID LEVEL LAPSE RATES SO WILL CONTINUE ISOLATED THUNDER...ALLOWING FOR STRONGER WORDING AS THE SCENARIO APPROACHES AND THE TIMING CAN BE PINNED DOWN MORE TIGHTLY. MINS WILL BE VERY MILD SUNDAY NIGHT...MID 50S TO LOWER 60S...GIVING A HEADSTART ON MONDAYS HIGHS...WHICH WILL PEAK IN THE 60S AS THE FRONT MOVES TO A POSITION EAST OF THE AREA BY MONDAY AFTERNOON. SHOWERS WILL LINGER IN THE EAST THROUGH PERHAPS MIDNIGHT MONDAY NIGHT...OTHERWISE COLD AIR ADVECTION WILL BE SURGING INTO THE AREA MONDAY NIGHT...WITH SKIES CLEARING FROM THE WEST AND TEMPS FALLING INTO THE 30S. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 25O PM FRIDAY... CLEAR AND MUCH COOLER TUESDAY AND CHRISTMAS DAY AS HIGH PRESSURE MIGRATES ACROSS THE OHIO VALLEY AND RIDGES DOWN THE ATLANTIC COAST. HIGHS WILL BE IN THE LOW AND MID 40S BOTH DAYS. MORNING LOWS WILL BE MOSTLY IN THE MID 20S CHRISTMAS MORNING. THERE IS CONSIDERABLE UNCERTAINTY IN THE LATE WEEK PERIOD AS THE UPCOMING COLD AIR DAMMING SCENARIO WILL ENCOURAGE DEVELOPMENT OF A TROF ALONG THE COAST. THIS COULD LEAD TO SOME CYCLOGENESIS AND UNSETTLED WEATHER IN THE EASTERN THIRD OF THE STATE BY FRIDAY. AT THIS POINT AIRMASS MODIFICATION LOOK TO ALLOW HIGHS TO SNEAK BACK UP TOWARDS THE CLIMATOLOGICAL RANGE OF UPPER 40S TO MID 50S THURSDAY AND FRIDAY. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 128 AM SATURDAY... VFR CONDITIONS EARLY THIS MORING MAY TRANSITION TO A PERIOD OF MVFR/LIFR CEILINGS BETWEEN 11-16Z...AS DIURNAL HEATING ACTS UPON AN INCREASINGLY MOIST AIR MASS NEAR THE SURFACE. CONFIDENCE OF THIS SUB- VFR OCCURENCE IS ABOUT 50 PERCENT...AND MOST LIKELY AT KFAY/ KRDU/KGSO. VFR CONDITIONS WITH A BREEZY SSW WIND WILL OTHERWISE PREVAIL THROUGH THE TAF PERIOD. LOOKING AHEAD: THE PROBABILITY OF LOW CLOUDS/STRATUS SHOULD CONTINUE TO INCREASE SATURDAY NIGHT/SUNDAY MORNING WITHIN STRENGTHENING MOISTURE TRANSPORT FEED FROM THE GULF...COMPLIMENTS OF A 50KT LLJ. SHOWERS WILL BECOME MORE NUMEROUS ACROSS THE AREA FROM WEST TO EAST LATE SUNDAY AFTERNOON AND INTO SUNDAY NIGHT WITH WIDESPREAD SUB-VFR CONDITIONS IN RAIN...POSSIBLY HEAVY AT TIMES...CONTINUING THROUGH MONDAY EVENING AS A SLOW MOVING COLD FRONT PUSHES EAST THROUGH THE AREA. VFR CONDITIONS ARE EXPECTED TO RETURN BY TUESDAY AND CONTINUE THROUGH THE REMAINDER OF THE PERIOD. && .CLIMATE... AS OF 230 PM WEDNESDAY... DAILY RECORDS FOR SATURDAY/SUNDAY DECEMBER 21/22 ARE AS FOLLOWS: RALEIGH/DURHAM... HIGHHI MIN DECEMBER 21... 71 DEGREES...SET IN 196759 DEGREES...SET IN 1923 DECEMBER 22... 75 DEGREES...SET IN 196761 DEGREES...SET IN 2011 -------------------------------------------------------------------- GREENSBORO... HIGHHI MIN DECEMBER 21... 66 DEGREES...SET IN 192355 DEGREES...SET IN 1984 DECEMBER 22... 71 DEGREES...SET IN 192360 DEGREES...SET IN 2011 -------------------------------------------------------------------- FAYETTEVILLE... HIGHHI MIN DECEMBER 21... 77 DEGREES...SET IN 193160 DEGREES...SET IN 1923 DECEMBER 22... 75 DEGREES...SET IN 201160 DEGREES...SET IN 2011 && .RAH WATCHES/WARNINGS/ADVISORIES... NONE && $$ SYNOPSIS...26 NEAR TERM...77/SMITH SHORT TERM...26/13 LONG TERM...MLM AVIATION...26/CBL CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
551 AM EST SAT DEC 21 2013 .SYNOPSIS... FRONT APPROACHES FROM THE WEST TODAY...PASSES AS COLD FRONT SUNDAY. SNOW SHOWERS POSSIBLE MONDAY NIGHT INTO TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... SURFACE BOUNDARY HAS BEEN SHIFTING EAST SLOWLY THROUGH THE NIGHT AND CURRENTLY RUNS FROM CENTRAL TEXAS NORTHEAST TO THE WESTERN SHORES LAKE ERIE. ONE WAVE IS NEAR DETROIT AND LIFTING NE...DRIVING PRECIP BISECTING OHIO. NEXT WAVE IS LIFTING INTO ARKANSAS WHICH IS MAYBE JUST A BIT FASTER THAN THE LOWER RES MODELS...BUT REPRESENTED FAIRLY WELL BY HIGHER RES MODELS LIKE HRRR AND RAP. SO TRENDED TOWARDS THESE HIGHER RES MODELS FOR POPS THIS MORNING AS THE WAVE MOVES INTO THE LOWER OHIO RIVER VALLEY WITH LIKELY POPS INTO SE OHIO. ANOTHER WAVE IS STARTING TO TAKE SHAPE IN EASTERN TEXAS WHICH WILL DRIVE ANOTHER AREA OF HIGHER POPS INTO SE OHIO TONIGHT. HAVE A BREAK BETWEEN THE TWO WAVES...BUT STILL HAVE SLIGHT CHANCE POPS EAST AND CHANCE POPS WEST THIS EVENING. THIS WILL ALSO BE THE WAVE THAT GETS THE BOUNDARY MOVING EAST AGAIN...SO HAVE THE FRONT JUST WEST OF CWA BORDER BY 12Z SUNDAY. NOT A WHOLE LOT OF INSTABILITY TODAY...BUT 850MB FLOW PUSHES 70-80KTS LATE THIS AFTERNOON INTO TONIGHT ACROSS WESTERN CWA...MAINLY IN SE OHIO AND NE KENTUCKY. THIS MATCHES SPCS SLIGHT RISK...AND WHILE THUNDER IS NOT EXPECTED...STRONGER SHOWERS SHOULD STILL BE ABLE TO TAP INTO THIS AND PRODUCE SOME ENHANCED OUTFLOW WINDS. WILL MENTION POTENTIAL FOR STRONG OUTFLOWS IN HWO FOR SE OHIO AND NE KY COUNTIES. DO HAVE SLIGHT CHANCE OF THUNDER JUST AHEAD OF THE FRONT EARLY SUNDAY MORNING...ANTICIPATING STRONG DYNAMIC FORCING. STILL...NOT EXPECTING WIDESPREAD THUNDER...BUT A RUMBLE OR TWO CANNOT BE RULED OUT. PLACEMENT OF HIGHEST QPF STILL LOOKS TO STAY WEST OF CWA...JUST CLIPPING NW CORNER LATE THIS AFTERNOON INTO TONIGHT...SO WILL NOT MAKE ANY CHANGES TO FLOOD WATCH AT THIS POINT. LITTLE TO NO CHANGE MADE TO HIGHS TODAY...GOING WELL ABOVE NORMAL FOR THE WINTER SOLSTICE. DID WARM UP LOWS TONIGHT A COUPLE DEGREES...AND WENT WITH A NON-DIURNAL TREND WITH NEARLY STEADY TEMPS THROUGH THE EARLY MORNING OUT AHEAD OF THE COLD FRONT. NOT THAT ITS AN OFFICIAL CLIMATE STATISTIC...BUT COULD BE CLOSE TO SETTING SOME RECORD HIGH MINIMUMS. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... SFC LOW WILL BE QUICKLY PUSHING NORTHEAST FROM ROUGHLY CENTRAL INDIANA TO THE EASTERN GREAT LAKES BTWN 12Z SUN AND 00Z MON. ATTENDANT COLD FRONT ALSO PROGGED TO BE JUST OUTSIDE THE WESTERN ZONES BY 12Z SUN AND WILL BE QUICKLY PUSHING ACROSS AS WELL. OVERALL FORECAST GENERALLY STILL ON TRACK...BUT DID SLOW DOWN THE PROGRESSION OF PRECIP ACROSS THE FORECAST AREA FROM WEST TO EAST BY ABOUT TWO-THREE HOURS...WITH THE HIGHEST CHANCE OVER THE WEST ZONES BY 12Z...CENTRAL ZONES BY 15Z...AND MOST PRECIP EAST OF THE I79 CORRIDOR BY 18Z. CONSENSUS OF MODEL OUTPUT STILL DEPICTING ABOUT 50KTS AT 925MB AND 70-80KTS AT 850MB. SPC HAS EXPANDED ITS SLIGHT RISK AREA OF SEVERE THUNDERSTORMS TO INCLUDE MOST OF THE SE OHIO AND NE KY COUNTIES. THE THREAT FOR A BRIEF SVR WIND GUST EXISTS FOR MOST LOCATIONS PRETTY MUCH ANYWHERE ALONG AND WEST OF I79 SUNDAY MORNING PRIMARILY AS THE MAIN CONVECTIVE LINE MARCHES ACROSS...BUT CERTAINLY THE SE OHIO COUNTIES ARE MOST PRONE TO THIS POSSIBILITY AS THE ASSOC LOWS AT 925MB AND 850MB MOVE NORTHEAST WITH THE SFC LOW. STILL EXPECTING GENERALLY A HALF INCH OR SO OF PRECIP WITH SOME HIGHER AMOUNTS AHEAD OF AND WITH THE FRONT. FOR MAX TEMPS...MOS GUIDANCE CONTINUING TO INSIST ON LOWER 70S. WENT LOWER THAN THIS HOWEVER WITH ONGOING CLOUDS AND PRECIP DURING THE MORNING HOURS AS COLD ADVECTION IS BEGINNING...SHOULD STILL BE IN THE LOW/MID 60S. MAY ACTUALLY SEE A FEW BREAKS IN THE CLOUDS ACROSS THE WESTERN ZONES BY 18Z-21Z...BUT BY THIS TIME 925MB AND 850MB TEMPS CONTINUE TO LOWER TO READINGS WHICH WOULD ONLY SUPPORT PERHAPS THE MID 60S ACROSS THOSE LOCATIONS. PRECIP WILL WIND DOWN DURING THE AFTERNOON HOURS EVEN FOR THE MOUNTAINS AS DEEP LAYER MOISTURE CONTINUES EASTWARD. ANOTHER DEVELOPING WAVE ALONG THE FRONT HOWEVER WILL QUICKLY BRING A RETURN TO PRECIP CHANCES MAINLY BTWN 06Z-12Z MON. THIS NEXT SFC WAVE WILL SLOW/DELAY THE COLD PUSH OF AIR INTO THE AREA. IN FACT...HAVE HOURLY TEMPS STILL IN THE LOWER 50S AROUND 06Z-08Z FOR LOWLANDS EAST OF I79...WITH MUCH COOLER TEMPS ACROSS THE SE OHIO ZONES. AS THIS NEXT SFC LOW ALSO PASSES TO THE NORTHEAST...WINDS WILL FINALLY COME AROUND TO THE NORTHWEST ALLOWING FOR THE COLD AIR TO FILTER FULLY INTO THE AREA. CODED UP SOMEWHAT OF A NON-DIURNAL TEMP CURVE FOR MONDAY...WITH SOME MODEST RECOVERY OF TEMPS ACROSS THE FAR NW ZONES...NEARLY STEADY TEMPS ACROSS THE CENTRAL AREAS...AND TEMPS CONTINUING TO SLOWLY DROP DURING THE DAY ACROSS THE EASTERN MOUNTAINS. SKIES SHOULD REMAIN MOSTLY CLOUDY TO CLOUDY FOR MOST WITH THIS COLD ADVECTION...BUT AGAIN MAY SEE SOME LATE DAY BREAKS FOR THE CENTRAL AND WEST ZONES. A COLD NIGHT IS IN STORE FOR THE AREA MONDAY NIGHT/TUE MORNING. SHOULD SEE MORE CLOUDS AND ANOTHER INCREASING CHANCE OF LIGHT SNOW/FLURRIES...ESPECIALLY ACROSS THE NORTH...TOWARDS THE DAWN HOURS TUE AS THE UPPER TROUGH FINALLY BEGINS TO SHIFT EASTWARD...WITH TROUGH AXIS PROGGED TO BE LOCATED OVER LAKE HURON SOUTH INTO OHIO BY 12Z TUE. LOWERED MINS JUST A BIT INTO THE LOWER 20S WITH LOW DEWPOINTS...BUT STAYED ABOVE THE LOWEST GUIDANCE WITH AFOREMENTIONED CLOUD COVER AND A CONTINUED 10-15KT BREEZE IN THE BOUNDARY LAYER. && .LONG TERM /TUESDAY THROUGH FRIDAY/... SOME UPSLOPE SNOW POSSIBLE MONDAY NIGHT INTO TUESDAY AS COLD AIR MOVES INTO THE REGION ON NORTHWEST FLOW. HIGH PRESSURE THEN BUILDS IN FOR CHRISTMAS DAY. USED THE ECMWF MEAN FOR THURSDAY AND FRIDAY...WHICH WOULD SHOW A FRONT MOVING THROUGH ON THURSDAY. BIG QUESTION ON FRIDAY IS HOW MUCH COLD AIR RESIDES BEHIND THE FRONT AND WHETHER ANY SNOW SHOWERS WILL BE ASSOCIATED WITH IT. WENT DRY FOR NOW AS PER MEAN...BUT CONFIDENCE IS NOT HIGH. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... IN GENERAL...VFR EXPECTED THROUGH MUCH OF THE DAY AT THE TAF SITES...HOWEVER COULD GET A PASSING MVFR CIG THIS MORNING. EXPECT MVFR TO IFR ACROSS SE OHIO...CLOSER TO A NEARLY STALLED SURFACE BOUNDARY. WILL ALSO HAVE BETTER CHANCE OF PRECIP TODAY ACROSS SE OHIO...BEFORE THE CHANCES OF RAIN INCREASE FROM WEST TO EAST THROUGH TONIGHT AS THE SURFACE BOUNDARY APPROACHES. WILL HAVE DROPS INTO MVFR AND IFR IN THE WEST TOWARD THE END OF THE TAF PERIOD. STRONG SW FLOW ALOFT WILL CONTINUE THROUGH THE TAF PERIOD WHICH WILL RESULT IN SURFACE WINDS GUSTING INTO THE 20 TO 30 KT RANGE THIS AFTERNOON AND TONIGHT. WITH FLOW REMAINING AT THE SURFACE...SHOULD NOT REACH LLWS CRITERIA. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z SUNDAY... FORECAST CONFIDENCE: MEDIUM TO HIGH. ALTERNATE SCENARIOS: TIMING OF MVFR MAY VARY. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22 EST 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY M H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY M H H H H H H H H H H H PKB CONSISTENCY M H H H H H M M M H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 12Z SUNDAY... IFR IN RAIN INTO SUNDAY. IFR POSSIBLE IN SNOW SHOWERS MONDAY NIGHT INTO TUESDAY. && .HYDROLOGY... MODEL CONSENSUS SHOWS MAIN SWATH OF PRECIP JUST TO THE WEST OF THE HSA. FOR THE WATCH AREA...EXPECT THE HEAVIEST RAINS TO OCCUR LATE SATURDAY INTO SATURDAY NIGHT. 1 TO 2 INCHES ARE POSSIBLE WITH LOCALLY HIGHER AMOUNTS. THE MAIN THREAT OF FLOODING IS FOR SMALL STREAMS AND CREEKS...ESPECIALLY IN LOW LYING AND POOR DRAINAGE AREAS. RISES ON THE MUSKINGUM ARE EXPECTED AS WELL. EVEN THOUGH THE HEAVIEST RAINFALL IS EXPECTED TO FALL JUST OUTSIDE HSA...RUNOFF AND STREAM FLOW WILL CONTINUE TO FLOW INTO THE WATCH AREA AND CAUSE ELEVATED LEVELS ON STREAMS AND CREEKS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...FLOOD WATCH THROUGH SUNDAY MORNING FOR OHZ066-067. KY...NONE. VA...NONE. && $$ SYNOPSIS...RPY/MZ/50 NEAR TERM...MZ SHORT TERM...50 LONG TERM...RPY AVIATION...MZ HYDROLOGY...MZ
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
440 AM EST SAT DEC 21 2013 .SYNOPSIS... FRONT APPROACHES FROM THE WEST TODAY...PASSES AS COLD FRONT SUNDAY. SNOW SHOWERS POSSIBLE MONDAY NIGHT INTO TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... SURFACE BOUNDARY HAS BEEN SHIFTING EAST SLOWLY THROUGH THE NIGHT AND CURRENTLY RUNS FROM CENTRAL TEXAS NORTHEAST TO THE WESTERN SHORES LAKE ERIE. ONE WAVE IS NEAR DETROIT AND LIFTING NE...DRIVING PRECIP BISECTING OHIO. NEXT WAVE IS LIFTING INTO ARKANSAS WHICH IS MAYBE JUST A BIT FASTER THAN THE LOWER RES MODELS...BUT REPRESENTED FAIRLY WELL BY HIGHER RES MODELS LIKE HRRR AND RAP. SO TRENDED TOWARDS THESE HIGHER RES MODELS FOR POPS THIS MORNING AS THE WAVE MOVES INTO THE LOWER OHIO RIVER VALLEY WITH LIKELY POPS INTO SE OHIO. ANOTHER WAVE IS STARTING TO TAKE SHAPE IN EASTERN TEXAS WHICH WILL DRIVE ANOTHER AREA OF HIGHER POPS INTO SE OHIO TONIGHT. HAVE A BREAK BETWEEN THE TWO WAVES...BUT STILL HAVE SLIGHT CHANCE POPS EAST AND CHANCE POPS WEST THIS EVENING. THIS WILL ALSO BE THE WAVE THAT GETS THE BOUNDARY MOVING EAST AGAIN...SO HAVE THE FRONT JUST WEST OF CWA BORDER BY 12Z SUNDAY. NOT A WHOLE LOT OF INSTABILITY TODAY...BUT 850MB FLOW PUSHES 70-80KTS LATE THIS AFTERNOON INTO TONIGHT ACROSS WESTERN CWA...MAINLY IN SE OHIO AND NE KENTUCKY. THIS MATCHES SPCS SLIGHT RISK...AND WHILE THUNDER IS NOT EXPECTED...STRONGER SHOWERS SHOULD STILL BE ABLE TO TAP INTO THIS AND PRODUCE SOME ENHANCED OUTFLOW WINDS. WILL MENTION POTENTIAL FOR STRONG OUTFLOWS IN HWO FOR SE OHIO AND NE KY COUNTIES. DO HAVE SLIGHT CHANCE OF THUNDER IN THE GRIDS JUST AHEAD OF THE FRONT EARLY SUNDAY MORNING...ANTICIPATING STRONG DYNAMIC FORCING. STILL...NOT EXPECTING WIDESPREAD THUNDER...BUT A RUMBLE OR TWO CANNOT BE RULED OUT. PLACEMENT OF HIGHEST QPF STILL LOOKS TO STAY WEST OF CWA...JUST CLIPPING NW CORNER LATE THIS AFTERNOON INTO TONIGHT...SO WILL NOT MAKE ANY CHANGES TO FLOOD WATCH AT THIS POINT. LITTLE TO NO CHANGE MADE TO HIGHS TODAY...GOING WELL ABOVE NORMAL FOR THE WINTER SOLSTICE. DID WARM UP LOWS TONIGHT A COUPLE DEGREES...AND WENT WITH A NON-DIURNAL TREND WITH NEARLY STEADY TEMPS THROUGH THE EARLY MORNING OUT AHEAD OF THE COLD FRONT. NOT THAT ITS AN OFFICIAL CLIMATE STATISTIC...BUT COULD BE CLOSE TO SETTING SOME RECORD HIGH MINIMUMS. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... SFC LOW WILL BE QUICKLY PUSHING NORTHEAST FROM ROUGHLY CENTRAL INDIANA TO THE EASTERN GREAT LAKES BTWN 12Z SUN AND 00Z MON. ATTENDANT COLD FRONT ALSO PROGGED TO BE JUST OUTSIDE THE WESTERN ZONES BY 12Z SUN AND WILL BE QUICKLY PUSHING ACROSS AS WELL. OVERALL FORECAST GENERALLY STILL ON TRACK...BUT DID SLOW DOWN THE PROGRESSION OF PRECIP ACROSS THE FORECAST AREA FROM WEST TO EAST BY ABOUT TWO-THREE HOURS...WITH THE HIGHEST CHANCE OVER THE WEST ZONES BY 12Z...CENTRAL ZONES BY 15Z...AND MOST PRECIP EAST OF THE I79 CORRIDOR BY 18Z. CONSENSUS OF MODEL OUTPUT STILL DEPICTING ABOUT 50KTS AT 925MB AND 70-80KTS AT 850MB. SPC HAS EXPANDED ITS SLIGHT RISK AREA OF SEVERE THUNDERSTORMS TO INCLUDE MOST OF THE SE OHIO AND NE KY COUNTIES. THE THREAT FOR A BRIEF SVR WIND GUST EXISTS FOR MOST LOCATIONS PRETTY MUCH ANYWHERE ALONG AND WEST OF I79 SUNDAY MORNING PRIMARILY AS THE MAIN CONVECTIVE LINE MARCHES ACROSS...BUT CERTAINLY THE SE OHIO COUNTIES ARE MOST PRONE TO THIS POSSIBILITY AS THE ASSOC LOWS AT 925MB AND 850MB MOVE NORTHEAST WITH THE SFC LOW. STILL EXPECTING GENERALLY A HALF INCH OR SO OF PRECIP WITH SOME HIGHER AMOUNTS AHEAD OF AND WITH THE FRONT. FOR MAX TEMPS...MOS GUIDANCE CONTINUING TO INSIST ON LOWER 70S. WENT LOWER THAN THIS HOWEVER WITH ONGOING CLOUDS AND PRECIP DURING THE MORNING HOURS AS COLD ADVECTION IS BEGINNING...SHOULD STILL BE IN THE LOW/MID 60S. MAY ACTUALLY SEE A FEW BREAKS IN THE CLOUDS ACROSS THE WESTERN ZONES BY 18Z-21Z...BUT BY THIS TIME 925MB AND 850MB TEMPS CONTINUE TO LOWER TO READINGS WHICH WOULD ONLY SUPPORT PERHAPS THE MID 60S ACROSS THOSE LOCATIONS. PRECIP WILL WIND DOWN DURING THE AFTERNOON HOURS EVEN FOR THE MOUNTAINS AS DEEP LAYER MOISTURE CONTINUES EASTWARD. ANOTHER DEVELOPING WAVE ALONG THE FRONT HOWEVER WILL QUICKLY BRING A RETURN TO PRECIP CHANCES MAINLY BTWN 06Z-12Z MON. THIS NEXT SFC WAVE WILL SLOW/DELAY THE COLD PUSH OF AIR INTO THE AREA. IN FACT...HAVE HOURLY TEMPS STILL IN THE LOWER 50S AROUND 06Z-08Z FOR LOWLANDS EAST OF I79...WITH MUCH COOLER TEMPS ACROSS THE SE OHIO ZONES. AS THIS NEXT SFC LOW ALSO PASSES TO THE NORTHEAST...WINDS WILL FINALLY COME AROUND TO THE NORTHWEST ALLOWING FOR THE COLD AIR TO FILTER FULLY INTO THE AREA. CODED UP SOMEWHAT OF A NON-DIURNAL TEMP CURVE FOR MONDAY...WITH SOME MODEST RECOVERY OF TEMPS ACROSS THE FAR NW ZONES...NEARLY STEADY TEMPS ACROSS THE CENTRAL AREAS...AND TEMPS CONTINUING TO SLOWLY DROP DURING THE DAY ACROSS THE EASTERN MOUNTAINS. SKIES SHOULD REMAIN MOSTLY CLOUDY TO CLOUDY FOR MOST WITH THIS COLD ADVECTION...BUT AGAIN MAY SEE SOME LATE DAY BREAKS FOR THE CENTRAL AND WEST ZONES. A COLD NIGHT IS IN STORE FOR THE AREA MONDAY NIGHT/TUE MORNING. SHOULD SEE MORE CLOUDS AND ANOTHER INCREASING CHANCE OF LIGHT SNOW/FLURRIES...ESPECIALLY ACROSS THE NORTH...TOWARDS THE DAWN HOURS TUE AS THE UPPER TROUGH FINALLY BEGINS TO SHIFT EASTWARD...WITH TROUGH AXIS PROGGED TO BE LOCATED OVER LAKE HURON SOUTH INTO OHIO BY 12Z TUE. LOWERED MINS JUST A BIT INTO THE LOWER 20S WITH LOW DEWPOINTS...BUT STAYED ABOVE THE LOWEST GUIDANCE WITH AFOREMENTIONED CLOUD COVER AND A CONTINUED 10-15KT BREEZE IN THE BOUNDARY LAYER. && .LONG TERM /TUESDAY THROUGH FRIDAY/... SOME UPSLOPE SNOW POSSIBLE MONDAY NIGHT INTO TUESDAY AS COLD AIR MOVES INTO THE REGION ON NORTHWEST FLOW. HIGH PRESSURE THEN BUILDS IN FOR CHRISTMAS DAY. USED THE ECMWF MEAN FOR THURSDAY AND FRIDAY...WHICH WOULD SHOW A FRONT MOVING THROUGH ON THURSDAY. BIG QUESTION ON FRIDAY IS HOW MUCH COLD AIR RESIDES BEHIND THE FRONT AND WHETHER ANY SNOW SHOWERS WILL BE ASSOCIATED WITH IT. WENT DRY FOR NOW AS PER MEAN...BUT CONFIDENCE IS NOT HIGH. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... EXPECT A MIX OF MVFR TO VFR CEILINGS THROUGH THE REST OF THE NIGHT...WITH THE BEST CHANCE OF SUSTAINED MVFR ALONG AND WEST OF THE OHIO RIVER. COULD ALSO GET ISOLATED SHOWERS ALONG AND WEST OF THE OHIO RIVER THROUGH THE EARLY MORNING HOURS...BUT BULK OF THE ACTIVITY WILL REMAIN WEST OF THE FORECAST AREA. SHOULD BE MAINLY VFR TODAY...WITH A FEW LIGHT SHOWERS WEST. THE CHANCES OF RAIN INCREASE THROUGH TONIGHT AS SURFACE BOUNDARY APPROACHES FROM THE WEST WITH DIPS INTO MVFR POSSIBLE LATE. STRONG SW FLOW ALOFT WILL CONTINUE THROUGH THE TAF PERIOD WHICH WILL RESULT IN SURFACE WINDS GUSTING INTO THE 15 TO 20 KT RANGE. WITH FLOW REMAINING AT THE SURFACE...SHOULD NOT REACH LLWS CRITERIA. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY... FORECAST CONFIDENCE: MEDIUM TO HIGH. ALTERNATE SCENARIOS: TIMING OF MVFR MAY VARY. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE SAT 12/21/13 UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H M M M M H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 06Z SUNDAY... IFR IN RAIN LATE SATURDAY NIGHT INTO SUNDAY. IFR POSSIBLE IN SNOW SHOWERS MONDAY NIGHT INTO TUESDAY. && .HYDROLOGY... MODEL CONSENSUS SHOWS MAIN SWATH OF PRECIP JUST TO THE WEST OF THE HSA. FOR THE WATCH AREA...EXPECT THE HEAVIEST RAINS TO OCCUR LATE SATURDAY INTO SATURDAY NIGHT. 1 TO 2 INCHES ARE POSSIBLE WITH LOCALLY HIGHER AMOUNTS. THE MAIN THREAT OF FLOODING IS FOR SMALL STREAMS AND CREEKS...ESPECIALLY IN LOW LYING AND POOR DRAINAGE AREAS. RISES ON THE MUSKINGUM ARE EXPECTED AS WELL. EVEN THOUGH THE HEAVIEST RAINFALL IS EXPECTED TO FALL JUST OUTSIDE HSA...RUNOFF AND STREAM FLOW WILL CONTINUE TO FLOW INTO THE WATCH AREA AND CAUSE ELEVATED LEVELS ON STREAMS AND CREEKS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...FLOOD WATCH FROM 7 AM EST THIS MORNING THROUGH SUNDAY MORNING FOR OHZ066-067. KY...NONE. VA...NONE. && $$ SYNOPSIS...RPY/MZ/50 NEAR TERM...MZ SHORT TERM...50 LONG TERM...RPY AVIATION...MZ HYDROLOGY...MZ
AREA FORECAST DISCUSSION
NWS TULSA OK
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. && .PRELIMINARY POINT TEMPS/POPS... TUL 17 30 14 41 / 10 10 0 0 FSM 22 38 21 43 / 10 10 0 0 MLC 20 40 17 45 / 10 10 0 0 BVO 13 26 10 39 / 10 10 0 0 FYV 18 32 11 39 / 10 10 0 0 BYV 17 31 11 34 / 10 10 0 0 MKO 18 34 15 42 / 10 10 0 0 MIO 15 26 9 39 / 10 10 0 0 F10 18 35 15 43 / 10 10 0 0 HHW 23 44 22 47 / 10 10 0 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...NONE. AR...NONE. && $$ SHORT TERM...07
AREA FORECAST DISCUSSION
NWS MEDFORD OR
857 AM PST SAT DEC 21 2013 .DISCUSSION...MOIST ONSHORE FLOW WILL PERSIST TODAY RESULTING IN THICK CLOUD COVER OVER THE WEST SIDE. MUCH OF THE CLOUD COVER WILL BE ALONG THE COAST AND BANKED UP AGAINST THE CASCADES AND SISKIYOUS. THERE WILL ALSO BE SCATTERED LIGHT RAIN OR DRIZZLE, ESPECIALLY NEAR THE MOUNTAINS AND FOOTHILLS. EXPECT A LITTLE IMPROVEMENT THIS AFTERNOON AS THE AIR MASS BEGINS TO DRY OUT A BIT...ESPECIALLY SOUTH OF THE UMPQUA DIVIDE. SO, WHILE NOT CERTAIN, THERE IS THE OPPORTUNITY TO SEE A FEW SUNNY BREAKS HERE IN MEDFORD TOWARD THE END OF THE DAY. VISIBLE IMAGERY IS SHOWING BREAKS IN THE CLOUDS IN NORTHERN CALIFORNIA AND OVER THE EAST SIDE THIS MORNING WITH SOME HIGH CLOUDINESS DUE TO MOUNTAIN WAVE ACTION AND THE STRONG WINDS ALOFT. THIS SHOULD PERSIST TODAY. HIGHS WILL BE MOSTLY IN THE 40S WITH SOME READINGS IN THE LOW 50S OVER ALONG THE COAST AND IN NORTHERN CALIFORNIA. SPILDE && .AVIATION...BASED ON THE 21/12Z TAF CYCLE. SCATTERED LIGHT PRECIPITATION WILL CONTINUE THIS MORNING WITH THE HIGHEST PROBABILITY OVER THE FOOTHILLS OF THE SOUTHERN OREGON CASCADES AND THE CASCADES THEMSELVES. THIS HAS CREATED MOUNTAIN OBSCURATIONS WITH MAINLY MVFR VSBYS AND CIGS, BUT WITH ISOLATED IFR CONDITIONS AND ALSO AREAS OF VFR CIGS. CONDITIONS WILL BEGIN TO IMPROVE AFTER LATE MORNING WITH CONTINUING MVFR CIGS MAINLY IN SOUTHWEST OREGON. SVEN && .PREV DISCUSSION... /ISSUED 403 AM PST SAT DEC 21 2013/ DISCUSSION... WHILE TEMPERATURES HAVE WARMED TO ABOVE FREEZING THIS MORNING AT MID AND UPPER ELEVATIONS AND TO THE LEE OF THE CASCADES, MOST INTERIOR VALLEY LOCATIONS HAVE BEEN HOVERING BETWEEN 30 AND 35 DEGREES. VERY LITTLE PRECIPITATION APPEARS TO HAVE FALLEN SINCE LAST EVENING AWAY FROM THE COAST AND UMPQUA BASIN, BUT SUSPECT WHAT HAS ALONG WITH WHAT FELL DURING THE EVENING HAS LED TO SOME ICY SPOTS IN THE STEEPER, MORE SHELTERED VALLEY LOCATIONS. A SPECIAL WEATHER STATEMENT HAS BEEN ISSUED FOR PORTIONS OF THE INTERIOR WEST SIDE AND AREAS EAST OF THE CASCADES HIGHLIGHTING WHERE THERE MAY BE A GLAZE OF ICE THIS MORNING. OTHERWISE, IT SHOULD BE NOTED THAT WINDS HAVE BEEN HOWLING IN THE HIGHER MOUNTAINS TO INCLUDE THE CRATER LAKE RIM, MOUNT SHASTA, AND PROBABLY ANYWHERE ABOVE ABOUT 6000 FEET. GUSTS IN THESE LOCATIONS OVERNIGHT RANGED FROM AROUND 40 MPH ON THE CRATER LAKE RIM TO 99 MPH AT GREY BUTTE AT 8000 FEET ON MOUNT SHASTA. WINDS APPEAR TO HAVE EASED A BIT BELOW 8000 FEET IN THE LAST HOUR, BUT EXPECT THEM TO REMAIN STRONG AT HIGHER ELEVATIONS THROUGH THIS EVENING. PRECIPITATION TODAY THROUGH THE WEEKEND WILL CONTINUE TO WANE WITH TIME. ONSHORE FLOW TODAY WILL BE FOCUSED ON THE WEST SIDE, AND PRECIPITATION WILL BE MOSTLY ALONG AND NEAR THE COAST AND COASTAL MOUNTAINS, UMPQUA BASIN, AND FOOTHILLS OF THE CASCADES NORTH OF ABOUT HIGHWAY 140. I HAVE SCALED BACK PRECIPITATION PROBABILITIES AND AMOUNTS SOME TO BE MORE IN ACCORDANCE WITH THE 3KM HRRR MODEL, AS IT SEEMS TO BE DEPICT WHAT HAS OCCURRED OVERNIGHT WELL. THIS AFTERNOON THROUGH NEXT WEEKEND THE ONLY EXPECTED TRAVEL PROBLEM WILL BE VALLEY FOG AND FREEZING FOG. A WEAK FRONTAL SYSTEM WILL DISSIPATE AS IT ARRIVES MONDAY INTO TUESDAY, WITH ANOTHER POSSIBLY DOING THE SAME NEXT WEEKEND. THUS, OUR COOL AND DRY DECEMBER LOOKS AS IF IT WILL CONTINUE AS SUCH. BTL && .MFR WATCHES/WARNINGS/ADVISORIES... OR...NONE. CA...NONE. PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM PST SUNDAY FOR PZZ350-356-370. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST SUNDAY FOR PZZ376. $$ MAS/BTL/SBN
AREA FORECAST DISCUSSION
NWS MEDFORD OR
403 AM PST SAT DEC 21 2013 .DISCUSSION... WHILE TEMPERATURES HAVE WARMED TO ABOVE FREEZING THIS MORNING AT MID AND UPPER ELEVATIONS AND TO THE LEE OF THE CASCADES, MOST INTERIOR VALLEY LOCATIONS HAVE BEEN HOVERING BETWEEN 30 AND 35 DEGREES. VERY LITTLE PRECIPITATION APPEARS TO HAVE FALLEN SINCE LAST EVENING AWAY FROM THE COAST AND UMPQUA BASIN, BUT SUSPECT WHAT HAS ALONG WITH WHAT FELL DURING THE EVENING HAS LED TO SOME ICY SPOTS IN THE STEEPER, MORE SHELTERED VALLEY LOCATIONS. A SPECIAL WEATHER STATEMENT HAS BEEN ISSUED FOR PORTIONS OF THE INTERIOR WEST SIDE AND AREAS EAST OF THE CASCADES HIGHLIGHTING WHERE THERE MAY BE A GLAZE OF ICE THIS MORNING. OTHERWISE, IT SHOULD BE NOTED THAT WINDS HAVE BEEN HOWLING IN THE HIGHER MOUNTAINS TO INCLUDE THE CRATER LAKE RIM, MOUNT SHASTA, AND PROBABLY ANYWHERE ABOVE ABOUT 6000 FEET. GUSTS IN THESE LOCATIONS OVERNIGHT RANGED FROM AROUND 40 MPH ON THE CRATER LAKE RIM TO 99 MPH AT GREY BUTTE AT 8000 FEET ON MOUNT SHASTA. WINDS APPEAR TO HAVE EASED A BIT BELOW 8000 FEET IN THE LAST HOUR, BUT EXPECT THEM TO REMAIN STRONG AT HIGHER ELEVATIONS THROUGH THIS EVENING. PRECIPITATION TODAY THROUGH THE WEEKEND WILL CONTINUE TO WANE WITH TIME. ONSHORE FLOW TODAY WILL BE FOCUSED ON THE WEST SIDE, AND PRECIPITATION WILL BE MOSTLY ALONG AND NEAR THE COAST AND COASTAL MOUNTAINS, UMPQUA BASIN, AND FOOTHILLS OF THE CASCADES NORTH OF ABOUT HIGHWAY 140. I HAVE SCALED BACK PRECIPITATION PROBABILITIES AND AMOUNTS SOME TO BE MORE IN ACCORDANCE WITH THE 3KM HRRR MODEL, AS IT SEEMS TO BE DEPICT WHAT HAS OCCURRED OVERNIGHT WELL. THIS AFTERNOON THROUGH NEXT WEEKEND THE ONLY EXPECTED TRAVEL PROBLEM WILL BE VALLEY FOG AND FREEZING FOG. A WEAK FRONTAL SYSTEM WILL DISSIPATE AS IT ARRIVES MONDAY INTO TUESDAY, WITH ANOTHER POSSIBLY DOING THE SAME NEXT WEEKEND. THUS, OUR COOL AND DRY DECEMBER LOOKS AS IF IT WILL CONTINUE AS SUCH. BTL && .AVIATION...BASED ON THE 21/06Z TAF CYCLE. A FEW WEAK DISTURBANCES WILL CONTINUE SCATTERED LIGHT PRECIPITATION OVERNIGHT INTO EARLY SATURDAY MORNING. THE PROBABILITY OF PRECIPITATION WILL BE HIGHEST OVER THE FOOTHILLS OF THE SOUTHERN OREGON CASCADES AND THE CASCADES THEMSELVES. PRECIPITATION WILL FALL MAINLY AS RAIN...INCLUDING AT THE TAF SITES. BUT THERE WILL BE LOCAL FREEZING RAIN...MAINLY IN NARROW VALLEYS WHERE FREEZING AIR WILL HAVE TROUBLE SCOURING OUT. THIS HAS CREATED MOUNTAIN OBSCURATIONS WITH MAINLY MVFR VSBYS AND CIGS, BUT WITH ISOLATED IFR CONDITIONS AND ALSO AREAS OF VFR CIGS. CONDITIONS WILL BEGIN TO IMPROVE AFTER 15Z SATURDAY MORNING WITH INCREASING COVERAGE OF VFR CIGS BUT WITH AREAS OF MVFR CIGS PERSISTING THROUGH THE AFTERNOON...MAINLY IN SOUTHWEST OREGON. DW && .MFR WATCHES/WARNINGS/ADVISORIES... OR...NONE. CA...NONE. PACIFIC COASTAL WATERS... - SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM PST SUNDAY FOR PZZ350-356-370. - SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST SUNDAY FOR PZZ376. $$ BTL/DW
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
549 AM CST SAT DEC 21 2013 .DISCUSSION... SEE THE 12Z AVIATION DISCUSSION BELOW. 40 && .AVIATION... THE FRONTAL BOUNDARY HAS MOVED EAST OF KCLL. THE RAP13 WAS DOING A VERY GOOD JOB THIS MORNING. USED THE MODEL ALMOST EXCLUSIVELY FOR KCLL AND INTERPOLATED ITS OUTPUT TO KUTS. THE MODEL WAVERS THE FRONTAL BOUNDARY BACK NORTHWARD BY AROUND 15Z BEFORE PUSHING IT SOUTHEASTWARD AGAIN AFTER 19Z. FURTHER TO THE SOUTH THE GUSTY SOUTHERLY WINDS WILL PERSIST WITH THE FRONT NOT MAKING ITS WAY THROUGH UNTIL ABOUT 19Z AT KCXO...AND THEN THE LATE AFTERNOON AT THE METRO HOUSTON AIRPORTS SOUTHWARD TO THE COAST. IFR CONDITIONS ARE MOST LIKELY FROM KIAH NORTHWARD. VFR IS EXPECTED TO DEVELOP DURING THE AFTERNOON OVER KCLL AND KUTS...BUT NOT UNTIL BETWEEN 23Z AND 03Z ELSEWHERE. 40 && .PREV DISCUSSION... /ISSUED 436 AM CST SAT DEC 21 2013/ UPDATE... A QUICK UPDATE TO ADJUST FOR TEMPS OVER THE NORTHWEST. DISCUSSION... THE RAP IS HANDLING TEMPS MUCH BETTER THAN ALL OTHER MODELS. FRONT WENT THROUGH CLL AND RWV WITH TEMPS NOW IN THE LOWER 40S. HAVE ADJUSTED HOURLY TEMP GRIDS TO REFLECT COOLER START OVER THE NORTHWEST. 43 PREV DISCUSSION... /ISSUED 400 AM CST SAT DEC 21 2013/ DISCUSSION... SHOWERS AND THUNDERSTORMS ARE INCREASING IN COVERAGE AND INTENSITY THIS MORNING AS A STRONG UPPER LEVEL LOW OVER SOUTHERN NEW MEXICO MOVES NE TOWARD CENTRAL OK. AT 3 AM...A STRONG SURFACE COLD FRONT EXTENDED FROM NEAR LONGVIEW TO PALASTINE TO AUSTIN. TEMPS ARE 36 AT WACO AND 72 AT COLLEGE STATION. THE COMBINATION OF THE TROUGH AND FRONT WILL SET THE STAGE FOR NUMEROUS SHRA/TSRA TODAY. SPC HAS ALL OF SE TX OUTLOOKED IN SLIGHT RISK...BUT THE RISK IS CONDITIONAL ON WHETHER CAPPING ERODES OR STAYS IN PLACE. SHEAR VALUES ARE EXTREMELY HIGH BUT OTHER SEVERE WEATHER PARAMETERS ARE FAIRLY TAME WITH CAPE VALUES LESS THAN 1000 J/KG. UPPER LEVEL WINDS LOOK FAVORABLE AS SE TX WILL LIE IN 140 KT RRQ AROUND 18Z. GFS FCST SOUNDING DATA IS CONSIDERABLY DRIER TODAY THAN YESTERDAY AND ACTUALLY MATCHES UP WELL WITH THE 00Z CRP SOUNDING SO HAVE SOME CONCERN THAT THE DRIER GFS SOLN MAY VERIFY. FCST SOUNDINGS SHOW THE CAPPING INVERSION ERODING BETWEEN 12-15Z. FCST SOUNDINGS ALSO SHOW A A FAIRLY DEEP DRY LAYER BETWEEN 850-700 MB WHICH NEVER FULLY SATURATES. STILL...ITS HARD TO IGNORE THE NEGATIVE TILT TO THE UPPER TROUGH...SFC BOUNDARY AND JET DYNAMICS. HAVE LEANED TOWARD A BLEND OF THE HI- RES ARW...RAP...NAM 12 AND ECWMF FOR TODAY. LOOKS LIKE SCT ACTIVITY WILL EVENTUALLY FORM A LINE OF STORMS SOMEWHERE OVER THE CENTRAL PORTION OF THE CWA BETWEEN 15-18Z. THE LINE OF STORMS WILL THEN PUSH THROUGH THE REST OF THE CWA BETWEEN 18-20Z. CAPPING IS LESS TOWARD THE NORTH AND EASTERN PORTIONS OF THE CWA SO FEEL BEST THREAT FOR SEVERE WEATHER WILL BE NORTHEAST OF A COLLEGE STATION TO HOUSTON TO GALVESTON LINE. THE PRIMARY SEVERE WEATHER HAZARD WILL WILL BE DAMAGING WINDS AND ISOLATED TORNADOES. IF CAPPING HOLDS...THE RISK FOR SEVERE WEATHER WILL GREATLY DIMINISH. IT WILL BE INTERESTING TO SEE THE 12Z SOUNDINGS. A SECONDARY SURGE OF COLDER AIR WILL ARRIVE ON SUNDAY ALONG WITH SOME MID LEVEL CLOUDINESS. HIGH TEMPS ON SUNDAY WILL BE ABOUT 20 DEGREES COOLER THAN TODAY. IT WILL STAY COOL FOR MUCH OF NEXT WEEK AS THE UPPER FLOW REMAINS SOMEWHAT AMPLIFIED. ANOTHER S/WV WILL DIG SSE ON WEDNESDAY AND THIS FEATURE WILL BRING SOME RAIN BACK TO SOUTHEAST TEXAS LATE IN THE DAY AND OVERNIGHT. THE CANADIAN IS THE MOST AGGRESSIVE WITH RAIN AND THE GFS WAS THE DRIEST. THE ECMWF WAS A NICE COMPROMISE. ANOTHER FRONT IS EXPECTED NEXT SATURDAY WHICH WILL REINFORCE THE ONGOING COOL CONDITIONS. 43 MARINE... SEA FOG CONTINUED TO AFFECT GALVESTON BAY EARLY THIS MORNING. THE FOG SHOULD LIFT LATER THIS MORNING AS SOUTHWESTERLY WINDS DEVELOP. THE COOLER WATERS OF THE BAYS AND NEARSHORE GULF WATERS WILL KEEP THE WIND SPEEDS DOWN THIS MORNING AS WELL. ADVISORY CONDITIONS WILL PERSIST OVER THE OFFSHORE WATERS. EXPECT WINDS WILL PICK UP OVER THE BAYS AND NEARSHORE WATERS TONIGHT AS THE FRONT MOVES OFF THE COAST. OTHERWISE...ANOTHER BOUT OF ADVISORY CONDITIONS ARE EXPECTED SUNDAY NIGHT AND MONDAY WITH THE PASSAGE OF A STRONGER FRONT. THE MODELS THEN RETURN ONSHORE WINDS BY LATE TUESDAY. 40 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 60 44 56 30 52 / 80 10 10 0 0 HOUSTON (IAH) 73 50 64 34 54 / 80 20 10 0 0 GALVESTON (GLS) 62 57 65 42 52 / 80 20 10 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR THE FOLLOWING ZONES: GALVESTON BAY...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. && $$ DISCUSSION...43 AVIATION/MARINE...40
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
436 AM CST SAT DEC 21 2013 .UPDATE... A QUICK UPDATE TO ADJUST FOR TEMPS OVER THE NORTHWEST. && .DISCUSSION... THE RAP IS HANDLING TEMPS MUCH BETTER THAN ALL OTHER MODELS. FRONT WENT THROUGH CLL AND RWV WITH TEMPS NOW IN THE LOWER 40S. HAVE ADJUSTED HOURLY TEMP GRIDS TO REFLECT COOLER START OVER THE NORTHWEST. 43 && .PREV DISCUSSION... /ISSUED 400 AM CST SAT DEC 21 2013/ DISCUSSION... SHOWERS AND THUNDERSTORMS ARE INCREASING IN COVERAGE AND INTENSITY THIS MORNING AS A STRONG UPPER LEVEL LOW OVER SOUTHERN NEW MEXICO MOVES NE TOWARD CENTRAL OK. AT 3 AM...A STRONG SURFACE COLD FRONT EXTENDED FROM NEAR LONGVIEW TO PALASTINE TO AUSTIN. TEMPS ARE 36 AT WACO AND 72 AT COLLEGE STATION. THE COMBINATION OF THE TROUGH AND FRONT WILL SET THE STAGE FOR NUMEROUS SHRA/TSRA TODAY. SPC HAS ALL OF SE TX OUTLOOKED IN SLIGHT RISK...BUT THE RISK IS CONDITIONAL ON WHETHER CAPPING ERODES OR STAYS IN PLACE. SHEAR VALUES ARE EXTREMELY HIGH BUT OTHER SEVERE WEATHER PARAMETERS ARE FAIRLY TAME WITH CAPE VALUES LESS THAN 1000 J/KG. UPPER LEVEL WINDS LOOK FAVORABLE AS SE TX WILL LIE IN 140 KT RRQ AROUND 18Z. GFS FCST SOUNDING DATA IS CONSIDERABLY DRIER TODAY THAN YESTERDAY AND ACTUALLY MATCHES UP WELL WITH THE 00Z CRP SOUNDING SO HAVE SOME CONCERN THAT THE DRIER GFS SOLN MAY VERIFY. FCST SOUNDINGS SHOW THE CAPPING INVERSION ERODING BETWEEN 12-15Z. FCST SOUNDINGS ALSO SHOW A A FAIRLY DEEP DRY LAYER BETWEEN 850-700 MB WHICH NEVER FULLY SATURATES. STILL...ITS HARD TO IGNORE THE NEGATIVE TILT TO THE UPPER TROUGH...SFC BOUNDARY AND JET DYNAMICS. HAVE LEANED TOWARD A BLEND OF THE HI- RES ARW...RAP...NAM 12 AND ECWMF FOR TODAY. LOOKS LIKE SCT ACTIVITY WILL EVENTUALLY FORM A LINE OF STORMS SOMEWHERE OVER THE CENTRAL PORTION OF THE CWA BETWEEN 15-18Z. THE LINE OF STORMS WILL THEN PUSH THROUGH THE REST OF THE CWA BETWEEN 18-20Z. CAPPING IS LESS TOWARD THE NORTH AND EASTERN PORTIONS OF THE CWA SO FEEL BEST THREAT FOR SEVERE WEATHER WILL BE NORTHEAST OF A COLLEGE STATION TO HOUSTON TO GALVESTON LINE. THE PRIMARY SEVERE WEATHER HAZARD WILL WILL BE DAMAGING WINDS AND ISOLATED TORNADOES. IF CAPPING HOLDS...THE RISK FOR SEVERE WEATHER WILL GREATLY DIMINISH. IT WILL BE INTERESTING TO SEE THE 12Z SOUNDINGS. A SECONDARY SURGE OF COLDER AIR WILL ARRIVE ON SUNDAY ALONG WITH SOME MID LEVEL CLOUDINESS. HIGH TEMPS ON SUNDAY WILL BE ABOUT 20 DEGREES COOLER THAN TODAY. IT WILL STAY COOL FOR MUCH OF NEXT WEEK AS THE UPPER FLOW REMAINS SOMEWHAT AMPLIFIED. ANOTHER S/WV WILL DIG SSE ON WEDNESDAY AND THIS FEATURE WILL BRING SOME RAIN BACK TO SOUTHEAST TEXAS LATE IN THE DAY AND OVERNIGHT. THE CANADIAN IS THE MOST AGGRESSIVE WITH RAIN AND THE GFS WAS THE DRIEST. THE ECMWF WAS A NICE COMPROMISE. ANOTHER FRONT IS EXPECTED NEXT SATURDAY WHICH WILL REINFORCE THE ONGOING COOL CONDITIONS. 43 MARINE... SEA FOG CONTINUED TO AFFECT GALVESTON BAY EARLY THIS MORNING. THE FOG SHOULD LIFT LATER THIS MORNING AS SOUTHWESTERLY WINDS DEVELOP. THE COOLER WATERS OF THE BAYS AND NEARSHORE GULF WATERS WILL KEEP THE WIND SPEEDS DOWN THIS MORNING AS WELL. ADVISORY CONDITIONS WILL PERSIST OVER THE OFFSHORE WATERS. EXPECT WINDS WILL PICK UP OVER THE BAYS AND NEARSHORE WATERS TONIGHT AS THE FRONT MOVES OFF THE COAST. OTHERWISE...ANOTHER BOUT OF ADVISORY CONDITIONS ARE EXPECTED SUNDAY NIGHT AND MONDAY WITH THE PASSAGE OF A STRONGER FRONT. THE MODELS THEN RETURN ONSHORE WINDS BY LATE TUESDAY. 40 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 66 44 56 30 52 / 80 10 10 0 0 HOUSTON (IAH) 73 50 64 34 54 / 80 20 10 0 0 GALVESTON (GLS) 62 57 65 42 52 / 60 20 10 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR THE FOLLOWING ZONES: GALVESTON BAY...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. && $$ DISCUSSION...43
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1155 PM CST FRI DEC 20 2013 .AVIATION... AN UPPER LEVEL DISTURBANCE OVER THE NORTHERN PART OF THE MEXICAN STATE OF CHIHUAHUA IS MOVING EAST TOWARD WEST TEXAS AS OF 0530Z. LIFT ASSOCIATED WITH THIS SYSTEM IS RESULTING IN A LARGE AREA OF RAIN WITH SOME EMBEDDED THUNDERSTORMS MAINLY WEST OF A K0F2 /BOWIE/ TO KILE /KILLEEN/ LINE. IN THE MEANTIME A COLD FRONT HAS NEARLY STALLED SOUTHEAST OF A LINE FROM KJDD /QUITMAN/ TO TEMPLE /KTPL/. TEMPERATURES AT THE METROPLEX TAF SITES AT 11 PM /05Z/ WERE IN 33 TO 39 DEGREES...AND WILL FALL TO 32 TO 35 DEGREES OVERNIGHT. SEVERAL ACARS/TAMDAR SOUNDINGS BETWEEN 04Z AND 05Z SHOW A FEW HUNDRED FEET OF SUB-FREEZING AIR BETWEEN 1200 AND 1800 FEET WITH TEMPERATURES MAXING OUT IN THE MID 50S AROUND 3000 FEET. AS THE RAIN INCREASES OVERNIGHT...THE RELATIVELY WARM RAIN DROPS SHOULD ALLOW TEMPERATURES TO ACTUALLY RISE A DEGREE OR TWO. THUS HAVE KEPT ALL OF THE PRECIPITATION LIQUID IN THE TAFS. A FEW THUNDERSTORMS ARE ALSO POSSIBLE OVERNIGHT INTO SATURDAY MORNING...FOR NOW HAVE JUST PLACED A TEMPO TSRA FOR THE MOST LIKELY TIME...10-14Z. IFR CONDITIONS WILL PREVAIL THROUGH MUCH OF THE DAY SATURDAY...WITH A GRADUAL IMPROVEMENT TO MVFR BY MID AFTERNOON AND SKIES SHOULD CLEAR DURING THE EVENING. 58 && .UPDATE... THE LATEST WATER VAPOR LOOP SHOWS THE UPPER LOW CENTER TRUDGING EAST AND GETTING CLOSER TO WEST TEXAS. LIFT IS ON THE INCREASE ACROSS NORTH AND CENTRAL TEXAS...AND PRECIPITATION COVERAGE IS EXPECTED TO RAMP UP OVER THE NEXT FEW HOURS. ISOLATED CONVECTION HAS BEGUN IN THE WARM SECTOR WITH A FEW LIGHTNING STRIKES SHOWING UP NEAR CANTON. MEANWHILE...THE SHALLOW ARCTIC AIRMASS HAS BARRELED FARTHER SOUTH INTO CENTRAL TEXAS AND THE 32 DEGREE ISOTHERM HAD DROPPED SOUTH OF POSSUM KINGDOM DURING THE PAST HOUR. WILL ADJUST LOWS DOWNWARD ACCORDINGLY...WHILE ADDING A FEW MORE COUNTIES TO THE RAIN/FREEZING RAIN MIX AREA WEST AND NORTHWEST OF THE DALLAS-FORT WORTH METROPLEX...WITH LITTLE OR NO ACCUMULATIONS STILL EXPECTED. 30 && .PREV DISCUSSION... /ISSUED 411 PM CST FRI DEC 20 2013/ 21Z SUBJECTIVE SURFACE ANALYSIS SHOWED A STRONG COLD FRONT IN PLACE ALONG A LINE FROM PARIS TO DALLAS TO HAMILTON. THE TEMPERATURE GRADIENT ALONG THIS BOUNDARY WAS QUITE IMPRESSIVE WITH A 70 DEGREE TEMPERATURE THAT WAS OBSERVED AT GREENVILLE...A 49 DEGREE TEMPERATURE AT MCKINNEY AND A 39 DEGREE TEMPERATURE AT DENTON. THIS FRONT WAS STILL MOVING SOUTHEAST AT 15 MPH AT THE TIME OF THIS DISCUSSION. A 20Z AIRPLANE SOUNDING FROM DALLAS LOVE FIELD INDICATED THAT THE FRONT WAS SHALLOW IN NATURE...WITH THE FRONTAL INVERSION ONLY EXTENDING UP ABOUT 1500 FEET ABOVE GROUND LEVEL. THE FRONT IS STILL EXPECTED TO STALL OUT OVER THE FAR SOUTHEASTERN CWA THIS EVENING...IN RESPONSE TO CYCLOGENESIS INITIATED BY THE APPROACH OF A POWERFUL UPPER LEVEL STORM SYSTEM. THIS UPPER LEVEL STORM SYSTEM WAS OBSERVED OVER BAJA CALIFORNIA AT 20Z BASED ON WATER VAPOR SATELLITE IMAGERY. OUT AHEAD OF THIS UPPER LEVEL STORM SYSTEM...WATER VAPOR SATELLITE IMAGERY SHOWED A NICE CONTINUOUS BAND OF SUB-TROPICAL PACIFIC MOISTURE STREAMING NORTHEAST OVER NORTHERN MEXICO AND THE SOUTH PLAINS. THE HIGH TERRAIN OF NORTHERN MEXICO WILL SCOUR OUT ALL OF THE LOW TO MID- TROPOSPHERIC MOISTURE ASSOCIATED WITH THIS SUBTROPICAL PLUME...BUT THE MID TO UPPER LEVEL MOISTURE WILL CONTRIBUTE TO MOISTURE DEPTH OVER THE REGION AS THE UPPER LEVEL STORM SYSTEM MOVES ACROSS THE AREA TONIGHT INTO TOMORROW MORNING. THROUGH TONIGHT...THE MOST TROUBLESOME FORECAST PROBLEM IN THE SHORT TERM FORECAST IS THAT ALL FORECAST GUIDANCE IS DOING A REMARKABLY POOR JOB RESOLVING THE STRENGTH OF THE SHALLOW COLD AIR ASSOCIATED WITH/BEHIND THE COLD FRONT. WHILE ALL GUIDANCE IS DOING A POOR JOB RESOLVING SURFACE TEMPERATURES NORTH OF THE COLD FRONT...THE RAP IN PARTICULAR IS DIFFICULT TO PROCESS BECAUSE IT CONTINUES TO INITIALIZE THE COLD AIR...BUT PERSISTENTLY BRINGS SURFACE TEMPERATURES UP 5-7 DEGREES AT FORECAST HOUR 1 DESPITE PERSISTENT COLD AIR ADVECTION AND CLOUD COVER. THIS WOULD BE MORE OR LESS A NUISANCE IF THE TEMPERATURES HAD NO POTENTIAL TO HAVE AN IMPACT ON PRECIPITATION TYPE IN THIS FORECAST. FOR INSTANCE...AT BOWIE...THE 21Z OBSERVATION HAD A TEMPERATURE OF 32 DEG F. THE RAP INITIALIZES THIS AT 34 DEGREES...WHICH IS NOT TOO FAR OFF...BUT THEN GOES AHEAD TO FORECAST A TEMPERATURE OF 40 DEGREES BY 22Z. WITH WIDESPREAD RAINFALL DEVELOPING OVER THE REGION RIGHT NOW...AND EXPECTED TO PERSIST THIS EVENING INTO THE OVERNIGHT HOURS...THIS ERROR IN RESOLVING NEAR SURFACE TEMPERATURES IS QUITE PROBLEMATIC. THEREFORE...AT THIS TIME...WITH NO GUIDANCE AVAILABLE ACTUALLY RESOLVING THE STRENGTH OF THIS COLD AIR...THE PRECIPITATION TYPE FORECAST FOR TONIGHT WAS COMPLETED USING OBSERVATIONAL TRENDS...RECENT FORECAST EVENTS AND INTUITION. AT THIS TIME EXPECT THAT TEMPERATURES ALONG AND NORTHWEST OF A GAINESVILLE TO GRAHAM LINE ARE MOST LIKELY TO FALL TO 32 DEGREES THIS EVENING...LIKELY HOLDING STEADY THROUGH MUCH OF THE OVERNIGHT HOURS. AS A RESULT...EVEN IF WE SEE RAIN AT 31 TO 32 DEGREES FOR SEVERAL HOURS...THE CURRENT THINKING IS THAT WE WILL NOT SEE ANY ICE ACCUMULATION...EXCEPT PERHAPS ON TREE TOPS OR THE TOPS OF EXPOSED METAL SURFACES. THE REASONS FOR THIS ARE AS FOLLOWS: 1. BEFORE THE FRONT...WE HAVE EXPERIENCED A FEW DAYS OF ABOVE NORMAL TEMPERATURES. GROUND/ROAD TEMPERATURES ARE WELL ABOVE FREEZING WHICH WILL NOT ALLOW FOR ICE ACCUMULATION. 2. THE DEPTH OF THE ELEVATED WARM LAYER IS ALMOST 8 TIMES AS DEEP AS THE DEPTH OF THE COLD/SUB-FREEZING LAYER. RAIN FALLING IN THIS ENVIRONMENT WILL LIKELY HAVE A TEMPERATURE ABOVE FREEZING WHEN IT REACHES THE SURFACE. THAT IS THE TEMPERATURE OF THE FALLING RAIN DROPS ARE LIKELY TO BE ABOVE FREEZING...THIS IS ALSO NOT CONDUCIVE TO ICE ACCUMULATION. 3. ALL GUIDANCE INDICATES PERSISTENT WARM AIR ADVECTION THROUGH 12Z SATURDAY ABOVE THE COLD FRONTAL INVERSION. THE WARM LAYER IS VERY LIKELY TO MAINTAIN ITS DEPTH AND STRENGTH...WHILE RELATIVELY WARM RAIN DROPS MAY ACTUALLY SHRINK THE DEPTH OF THE SHALLOW COLD AIR OVERNIGHT. AS A RESULT...WILL NOT BE HIGHLIGHTING FREEZING RAIN IN THE FORECAST AT THIS TIME...DESPITE THE SURFACE OBSERVATION AT BOWIE AT 32 DEGREES SEEMINGLY SHOWING AN ICE STORM ON OUR DOORSTEP. IT LOOKS LIKE THE DEPTH OF THE COLD AIR WILL ONLY SUPPORT ICE ACCUMULATION FARTHER NORTH...WELL INTO OKLAHOMA BASED ON OBSERVATIONAL ANALYSIS AND DFW AREA AIRCRAFT SOUNDINGS. DESPITE ALL THAT HAS BEEN DISCUSSED ABOUT THE SHALLOW COLD AIR PROBLEM...THERE WERE ACTUALLY NO SIGNIFICANT CHANGES MADE TO THE PREVIOUS FORECAST WHICH REMAINS LARGELY ON TRACK. THE BAJA UPPER LEVEL LOW IS STILL EXPECTED TO MOVE OVER THE SOUTH PLAINS TOMORROW MORNING...SPREADING STRONG LARGE SCALE FORCING FOR ASCENT OVER THE REGION TONIGHT THROUGH TOMORROW MORNING. NEARLY ALL GUIDANCE INDICATES THAT THE UPPER LOW WILL BECOME INCREASINGLY NEGATIVELY TILTED AS IT MOVES OUT OVER TEXAS...DEEPENING AS IT MOVES OVER THE CWA. THE STRONGEST FORCING FOR ASCENT LOOKS TO MOVE OVER THE CWA IN THE 09 TO 15Z TIME FRAME...WHICH SHOULD ALSO REPRESENT OUR WINDOW FOR THE BEST COVERAGE AND HEAVIEST PRECIPITATION RATES DURING THIS EVENT. FOR THIS EVENING...THE COLD FRONT PUSHING SOUTH THROUGH MOST OF THE CWA WILL SIMPLY HELP TO STEEPEN LOW-LEVEL ISENTROPIC SURFACES AS CYCLOGENESIS RAMPS UP NEAR DEL RIO RESULTING IN AN INCREASE OF THE STRENGTH OF THE LOW TO MID-LEVEL WIND FIELD. THIS SHOULD RESULT IN A SPREAD OF THE COVERAGE OF ONGOING RAIN SHOWER ACTIVITY FROM WEST TO EAST ACROSS THE CWA. AS THE UPPER LEVEL LOW APPROACHES...ASSUMING IT BECOMES MORE NEGATIVELY TILTED AS ADVERTISED...WE SHOULD SEE AN ENHANCEMENT OF MID-LEVEL LAPSE RATES WITH SOME UPPER-LEVEL COLD AIR ADVECTION OVER THE PERSISTENT LOW- LEVEL WARM AIR ADVECTION REGIME. THIS WILL RESULT IN AN INCREASED CHANCE OF ISOLATED THUNDERSTORMS EMBEDDED IN THE RAIN SHOWER ACTIVITY FROM SUNSET TO MIDNIGHT. ALL OF THIS ACTIVITY SHOULD REMAIN ELEVATED IN NATURE...AND POSES VERY LITTLE SEVERE WEATHER THREAT AS A RESULT. RAINFALL RATES WILL BE ENHANCED...AND THEREFORE SOME LOCALIZED HEAVY RAINFALL IS POSSIBLE. AFTER MIDNIGHT...AS MENTIONED ABOVE...THE BEST LARGE SCALE FORCING FOR ASCENT IS EXPECTED TO BUILD ACROSS THE CWA FROM WEST TO EAST DURING THIS TIME RESULTING IN THE STRONGEST AND MOST WIDESPREAD CONVECTION AND PRECIPITATION FOR THE REGION. BASED ON THE POSITION OF THE COLD FRONT AT THAT TIME...WE DO HAVE A WINDOW FOR SURFACE BASED SEVERE STORMS BASED ON CONVECTIVE PARAMETERS ADVERTISED IN THE MAJORITY OF GUIDANCE. LOCATIONS ALONG AND SOUTHEAST OF WHEREVER THE COLD FRONT STALLS OUT WOULD BE THE ONLY LOCATIONS WHERE SURFACE BASED SEVERE STORMS WOULD BE POSSIBLE. FORECAST CONVECTIVE PARAMETERS INDICATED SURFACE BASED CAPE VALUES OF AROUND 1000 J/KG WITH 0-3 KM CAPE VALUES OF AROUND 100 J/KG AND DEEP LAYER SHEAR VALUES IN EXCESS OF 50 KTS. THESE VALUES ARE SUPPORTIVE OF A LOW-TOPPED SUPER CELLULAR STORM MODE...WHICH COULD RESULT IN LARGE HAIL...DAMAGING WIND OR ISOLATED TORNADOES. THIS THREAT IS MODERATED BY STRONG FORCING WHICH MAY MAKE AN ISOLATED STORM MODE DIFFICULT TO REALIZE...AND STRONG CLOUD LEVEL WINDS THAT WILL LIKELY TAKE STORMS THAT DEVELOP ALONG THE FRONT...OVER/NORTH OF THE FRONT SHORTLY AFTER INITIATION. REGARDLESS...WILL BE WATCHING FOR WHERE THE FRONT STALLS OUT TONIGHT AS LOCATIONS NEAR AND TO THE SOUTHEAST OF THE BOUNDARY ARE THE MOST LIKELY TO SEE SEVERE WEATHER. FURTHER NORTHWEST...STRONG STORMS REMAIN POSSIBLE...HOWEVER EVEN ELEVATED SUPERCELLS ARE ONLY GOING TO PROVIDE A THREAT FOR MARGINALLY SEVERE HAIL...SO THE OVERALL SEVERE WEATHER THREAT NORTHWEST OF THE FRONT DIMINISHES GREATLY. FOR ANYWHERE ACROSS NORTH TEXAS...LOCALLY HEAVY RAINFALL IS POSSIBLE WHICH MAY RESULT IN SOME LOCALIZED FLASH FLOODING ISSUES OVER THE NEXT 24 HRS. WITH THE SUB-TROPICAL PACIFIC MOISTURE FEED IN PLACE...AND LOW-LEVEL WARM MOIST ADVECTION EXPECTED TO RAMP UP IN INTENSITY OVER THE SHALLOW COLD FRONT...NEARLY ALL GUIDANCE INDICATES THAT PWAT VALUES WILL BE UP AROUND 1.5 INCHES ACROSS NORTH AND CENTRAL TEXAS AS THE UPPER LOW SPREADS STRONG FORCING OVER THE REGION. 1.5 INCH PRECIPITABLE WATER VALUES RANK AS PLUS 3 STANDARD DEVIATION FOR NORTH TEXAS AT THIS TIME OF YEAR. THIS EXCEPTIONALLY DEEP MOISTURE COMBINED WITH FAVORABLE DYNAMICS FOR WIDESPREAD PRECIPITATION SUPPORT A LOCALIZED HEAVY RAINFALL THREAT WITH AN ATTENDANT LOCALIZED FLOODING THREAT TONIGHT INTO TOMORROW MORNING. DID NOT ISSUE A FLASH FLOOD WATCH AT THIS TIME BECAUSE OUR PRIMARY WINDOW FOR HEAVY RAINFALL IS ONLY EXPECTED TO BE ON THE ORDER OF 6 HOURS OR SO. IF STRONG FORCING WAS EXPECTED TO BE IN PLACE FOR A LONGER PERIOD OF TIME...THE THREAT OF WIDESPREAD FLOODING WOULD BE MUCH GREATER AND A WATCH WOULD HAVE BEEN ISSUED. AT THIS TIME THE THREAT OF FLOODING IS EXPECTED TO REMAIN LOCALIZED AND MAINLY CONFINED TO LOW LYING/COMMONLY FLOODED AREAS. HEAVY PRECIPITATION IS EXPECTED TO COME TO AN END FROM SOUTHWEST TO NORTHEAST SATURDAY AFTERNOON AS A STRONG MID-LEVEL DRY SLOT PUNCHES OVER THE REGION. LIGHT RAIN MAY PERSIST ACROSS THE AREA SATURDAY AFTERNOON...BUT EVEN THIS WILL BE SCOURED OUT BY SUNSET. REMAINDER OF THE FORECAST...NO SIGNIFICANT CHANGES WERE MADE TO THE PREVIOUS FORECAST AS MOST OF THE ACTIVITY IN THE FORECAST IS IN THE FIRST 24 HOURS. HIGHLIGHTS OF THE REMAINDER OF THE FORECAST INCLUDE: 1. ADDED A MENTION OF SPRINKLES/LIGHT RAIN TO THE FORECAST ALONG THE COLD FRONT THAT IS EXPECTED TO PUSH SOUTH THROUGH THE CWA ON SUNDAY MORNING. WILL HAVE TO WATCH TEMPERATURES CLOSELY SUNDAY MORNING AS THIS FRONT ROLLS THROUGH...HOWEVER ALL GUIDANCE INDICATES TEMPERATURES JUST ABOVE FREEZING WITH THIS VERY LIGHT PRECIPITATION. 2. WE SHOULD BE DRY EARLY NEXT WEEK...LEADING UP TO CHRISTMAS DAY. TEMPERATURES WILL SLOWLY WARM THROUGH CHRISTMAS...ALTHOUGH HIGHS ARE EXPECTED TO REMAIN BELOW NORMAL THROUGH THE WEEK AHEAD. 3. AN UPPER LEVEL STORM SYSTEM MAY RESULT IN SCATTERED RAIN SHOWERS ACROSS THE REGION ON CHRISTMAS DAY. AT THIS TIME TEMPERATURES ARE EXPECTED TO BE WELL ABOVE FREEZING...SO NO SIGNIFICANT IMPACTS ARE EXPECTED AT THIS TIME. CAVANAUGH && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 36 47 36 48 29 / 100 100 10 10 5 WACO, TX 42 62 37 50 30 / 80 100 10 10 5 PARIS, TX 41 45 36 47 26 / 100 100 10 10 10 DENTON, TX 33 44 34 47 26 / 100 100 10 10 5 MCKINNEY, TX 35 44 35 46 25 / 100 100 10 10 5 DALLAS, TX 37 46 38 48 30 / 100 100 10 10 5 TERRELL, TX 41 47 37 47 28 / 100 100 10 10 5 CORSICANA, TX 46 54 39 48 30 / 80 100 10 10 5 TEMPLE, TX 41 63 39 52 31 / 80 100 10 10 5 MINERAL WELLS, TX 31 49 34 48 24 / 100 90 10 10 5 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 58/30
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1135 PM CST FRI DEC 20 2013 .DISCUSSION... UPDATED AVIATION SECTION. && .AVIATION... AGAIN CHALLENGING 06Z TAF PACKAGE. CURRENTLY SURFACE ANALYSIS SHOWS SURFACE LOW DEVELOPING OVER CENTAL TX. AN AREA OF RAIN WITH EMBEDDED THUNDERSTORMS IS ASSOCIATED WITH THIS LOW AND FRONTAL ZONE. WATER VAPOR SHOWING UPPER LOW AND ASSOCIATED JET MAKING ITS WAY INTO WEST TEXAS. ANOTHER AREA OF RAIN WITH EMBEDDED THUNDER WAS ASSOCIATED WITH THIS FEATURE. EAST OF THESE TWO RAIN AREAS WERE SOME VERY LIGHT SHOWERS OCCURRING AS MOISTURE ADVECTS IN OFF THE GULF AND WITH A SMALL AMOUNT OF CAPE BELOW THE CAPPING INVERSION. TAKING ALL THESE SYSTEMS INTO ACCOUNT...EXPECT CAPPING INVERSION TO KEEP PRECIPITATION INITIALLY IN THE FORM OF VERY LIGHT RAIN SHOWERS...BUT WITH COOLING ALOFT AND LIFT ASSOCIATED WITH APPROACHING UPPER LOW...GREATER THREAT OF HEAVIER RAIN AND THUNDERSTORMS TO FIRST REACH CLL AROUND DAYBREAK...THE HOUSTON AREA AIRPORTS BETWEEN MID MORNING AND EARLY AFTERNOON....AND GALVESTON WITH SURFACE FRONTAL PASSAGE MID AFTERNOON. SITUATION IS MOST COMPLEX FOR CLL AS FIRST RAIN AREA WITH EMBEDDED THUNDER COULD BRUSH THAT AREA IN THE PRE DAWN HOURS. SOME POTENTIAL FOR GUSTY WINDS WITH THE STRONGER STORMS AS LOW LEVEL JET VERY STRONG. CEILINGS MAINLY MVFR BUT WITH AREAS OF OR TEMPO IFR AS ARE CURRENTLY OCCURING. 46 && .PREV DISCUSSION... /ISSUED 910 PM CST FRI DEC 20 2013/ UPDATE... THE ONLY CHANGE ON THIS SHIFT WAS TO ADJUST SHORT TERM POPS/WX TO BETTER COME IN-LINE WITH ONGOING TRENDS. DURING THE 8 PM HOUR...THE COLD FRONT IS WORKING ITS WAY SOUTHWARD AND NOW PUSHING INTO THE SOUTHERN COUNTIES OF DFW`S CWA. DOWNSTREAM OF THIS MAIN BOUNDARY... VERY LIGHT RAIN SHOWERS OR DRIZZLE AFFECTING OUR FA...MOVING NORTH WITHIN A VERY PERSISTENT SWATH OF 40 KT JUST-OFF-THE-SURFACE SOUTHERLY (LLJ) FLOW. A VERY WARM AND MOIST OVERNIGHT WITH SEA FOG LOWERING MARITIME VISIBILITIES TO UNDER A COUPLE OF MILES AT TIMES...LOCALLY DENSE AT A MILE OR UNDER ESPECIALLY IF NEARSHORE SOUTHERLIES BACK A BIT MORE EASTERLY WITH TIME. MINIMUM TEMPERATURES WILL BE A DEGREE OR TWO OFF 70 F...WITH SIGNIFICANTLY GREATER CONVECTIVE CHANCES FROM AROUND 21/09Z ONWARD OVER THE NORTHERN FORECAST AREA. THE HRRR DISPLAYING THE FORMATION OF MORE DISCRETE CELLS FROM SHORTLY AFTER MIDNIGHT THROUGH SUNRISE. OUR MOISTENED DOWNSTREAM ENVIRONMENT IS HIGHLY SHEARED AFFORDING HIGH HELICITY AND SIGNALING THAT MANY UPDRAFTS WILL ROTATE. SPC HAS THE NORTHERN THIRD OF THE CWA HIGHLIGHTED IN SLIGHT RISK TO ACCOUNT FOR THIS EARLY MORNING THROUGH EARLY AFTERNOON THREAT FOR STRONG CELLS...POSSIBLY WITHIN A BROKEN WEST-MOVING-EAST QLCS...REACHING SEVERE LIMITS. DAMAGING WINDS AND TORNADOES WILL BE THE MAIN THREATS THROUGH MID-SATURDAY. 31 PREV DISCUSSION... /ISSUED 554 PM CST FRI DEC 20 2013/ DISCUSSION... UPDATED AVIATION FOR OOZ TAFS. AVIATION... TRICKY FORECAST WITH CEILING HEIGHTS OVERNIGHT...AND TIMING OF THE THUNDERSTORM THREAT BEING THE BIGGEST CHALLENGES. ALREADY SEEING CIGS IN THE 1000 TO 1200 FOOT RANGE SOME LOCATIONS. GLS SOCKED IN WITH SEA FOG AND HALF MILE VISIBILITY. RADAR SHOWING LIGHT RETURNS INCREASING ASSOCIATED WITH VERY LIGHT SHOWERS OR SPRINKLES. OVERNIGHT AM IN GENERAL GOING WITH MVFR CIGS PREVAILING...NEAR CURRENT LEVELS BUT THINK THERE WILL BE A WINDOW OF CIGS BLO 1000 FEET AT MOST AIRPORTS AND HAVE INDICATED THAT WITH A TEMPO GROUP OVERNIGHT MOST SITES. THUNDERSTORM THREAT WILL BE SATURDAY MORNING FOR CLL AND UTS...MORE MIDDAY AND EARLY AFTERNOON FOR CXO AND IAH AND AFTERNOON FOR HOU...SGR...LBX AND GLS. MOST LIKELY SCENARIO WILL BE NUMEROUS LIGHT SHOWERS UNDERNEATH THE CAP BEFORE THEN...THEN THE DEVLOPMENT OF A LINE OF STORMS THAT WILL MOVE QUICKLY OVER THE AREA. THREAT SHOULD BE EAST OF THE TAF SITES BY LATE TOMORROW AFTERNOON. 46 PREV DISCUSSION... /ISSUED 406 PM CST FRI DEC 20 2013/ SLIGHT RISK OF SEVERE WEATHER TONIGHT INTO SATURDAY... DISCUSSION... SFC ANALYSIS HAS COLD FRONT PUSHING THROUGH DFW METROPLEX HEADED TOWARDS A TYLER/WACO LINE. FRONT SHOULD PUSH CLOSE TO A COLLEGE STATION TO CROCKETT LINE TONIGHT BUT LIKELY STALL JUST NORTH. MOISTURE HAS DEEPENED WITH SFC DEWPOINTS IN THE 70S. SEA FOG MAY BE AN ISSUE ALONG THE COAST SO WILL HAVE ANOTHER DENSE FOG ADVISORY FOR THE COAST TONIGHT. SHOWERS SHOULD INCREASE OVERNIGHT WITHIN MAY MOISTURE AXIS THROUGH THE AREA. SO REALLY NO CHANGES IN THE FORECAST THROUGH TONIGHT. UPPER AIR ANALYSIS AND WATER VAPOR IMAGERY SHOW STRONG UPPER LOW MOVING ACROSS NORTHERN MEXICO AND S ARIZONA. UPPER LOW SHOULD REACH EL PASO AND BIG BEND AREA BY 12Z SAT WITH HEIGHT FALLS OVER TX AND LARGE SCALE ASCENT SPREADING INTO THE AREA. THIS SHOULD SUPPORT THUNDERSTORM ACTIVITY ALONG THE FRONTAL BOUNDARY TONIGHT WHICH MAY STALL JUST NORTH OF COLLEGE STATION. SPC HIGHLIGHTS SMALL SEVERE WEATHER PROBS FOR THIS SCENARIO. AS THE UPPER LOW MOVES EAST...EXPECT ANOTHER LINE OF STORMS TO FORM ALONG APPROACHING PACIFIC FRONT WHICH SHOULD PUSH INTO THE ARE DURING THE MORNING. THE 12Z TX TECH WRF AND 4KM WRF-ARW SHOW THIS LINE DEVELOPING IN THE PRE-DAWN HOURS AND MOVING INTO THE AREA. BASICALLY LEFT 60/70 POPS FOR OVERNIGHT TIME FRAME TO ACCOUNT FOR THIS POSSIBILITY BUT FEEL MOST THUNDERSTORM ACTIVITY WILL BE DURING THE DAY SATURDAY. SATURDAY WILL BE MORE SPRING LIKE WITH REGARDS TO THUNDERSTORM ACTIVITY THAN THE FIRST DAY OF WINTER. MODELS ARE ALL ON THE SAME PAGE WITH HOW THE UPPER LOW MOVES TOWARDS C/NE OK BY 00Z SUN. MAIN CONCERN WILL BE WHETHER STRONG MID LEVEL CAP WILL ERODE. 850MB TEMPS LOOK TO WARM NEAR 16-20C ON THE GFS BY 18Z SAT. THE NAM ERODES THE CAP QUITE A BIT DURING THIS TIME. THE PROBLEM IS THAT NONE OF THE MODELS REALLY BRING GOOD PVA OVER THE AREA AND KEEP IT NORTH OF THE AREA. OMEGA FIELDS SUPPORT BREAKING THE CAP BUT HAVE SEEN SEVERAL TIMES BEFORE WHERE THE CAP HOLDS PRETTY STRONG. MAIN QUESTION WILL BE WHEN EXACTLY THE CAP WILL BREAK. IF THE NAM HOLDS TRUE THEN QUITE POSSIBLE TO GET DISCRETE SUPERCELLS AHEAD OF THE DEVELOPING QLCS. HAVE NO QUESTION ABOUT OTHER SEVERE PARAMETERS AS DEEP LAYER SHEAR AND LOW LEVEL SHEAR WILL BE OFF THE CHARTS GIVEN STRONG LLJ AND UPPER LEVEL JET. UPPER LEVEL JET STREAK DYNAMICS WITH RIGHT ENTRANCE REGION MOVING OVER THE AREA MAY JUST BE ENOUGH TO ERODE THE CAP. ALL POINTS TO BASICALLY 15-21Z BEING THE FAVORED TIME FOR SEVERE STORMS MORE LIKELY 15-18Z. OTHER LIMITING FACTOR WILL BE INSTABILITY AS COOLING ALOFT MAY NOT BE QUITE ENOUGH TO PUSH CAPE TO ABOVE 1500 J/KG. THINK 1000 J/KG MORE LIKELY AND THIS STILL COULD BE ENOUGH TO SUPPORT ROBUST UPDRAFTS FOR ROTATION. THINK SPC DAY 2 OUTLOOK IS GOOD BUT REALLY DO NOT WANT TO UNDER- ESTIMATE THE CAP AND UPPER LEVEL DYNAMICS BEING JUST ENOUGH OUT OF PHASE THAT A LINE OF STRONG STORMS RESULTS. STILL QUITE A BIT OF UNCERTIANTY IN THE FORECAST BUT ENOUGH CONFIDENCE THAT THE SEVERE POTENTIAL SHOULD BE HIGHLIGHTED. TRUE COLD FRONT WILL PUSH THROUGH DURING THE DAY SUNDAY SO TEMPS MAY BE A TOUCH WARMER THAN EXPECTED. HOWEVER MON/TUE AND EVEN CHRISTMAS DAY WILL CERTAINLY FEEL LIKE WINTER AROUND SE TX. GFS/ECMWF STILL TRYING TO SORT OUT RETURN FLOW CHRISTMAS DAY INTO THURSDAY. WILL KEEP SOME 20 POPS DURING THAT TIME BUT REALLY DO NOT HAVE A GOOD FEEL FOR PRECIP. LIKELY DEPENDS ON WHERE STRONGEST ISENTROPIC LIFT SETS UP AND MODELS DIFFER BY SEVERAL HUNDERED MILES ON WHERE THAT IS. ALSO NOTICED THAT ECMWF IS STRONGER WITH COLD FRONT LATE NEXT THAN THE GFS WHICH HAS SEEMED TO BACK OFF. OVERALL KEPT TREND OF ECMWF KEEPING TEMPS COLDER. 39 MARINE... PATCHY FOG REMAINS PROBLEMATIC IN AND AROUND GALVESTON BAY WITH VISIBILITIES FALLING TO BELOW ONE MILE AT TIMES. WITH CONDITIONS EXPECTED TO DETERIORATE THROUGH THE EVENING HAVE ISSUED A MARINE DENSE FOG ADVISORY FOR GALVESTON BAY AND THE ADJACENT NEARSHORE WATERS THROUGH EARLY SATURDAY. SMALL CRAFT ADVISORY WILL REMAIN IN PLACE FOR THE OFFSHORE WATERS THROUGH THE OVERNIGHT HOURS WITH CAUTION FLAGS RAISED ACROSS THE NEARSHORE WATERS AND BAYS AS WINDS INCREASE THIS EVENING. 38 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 69 72 45 62 31 / 50 80 10 10 0 HOUSTON (IAH) 70 77 49 69 35 / 40 70 30 10 0 GALVESTON (GLS) 65 71 55 68 42 / 20 60 30 10 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH SATURDAY AFTERNOON FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY... WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. DENSE FOG ADVISORY UNTIL 5 AM CST SATURDAY FOR THE FOLLOWING ZONES: GALVESTON BAY...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. SMALL CRAFT ADVISORY UNTIL 3 PM CST SATURDAY FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. && $$ DISCUSSION...99 AVIATION/MARINE...99
AREA FORECAST DISCUSSION
NWS SPOKANE WA
445 AM PST Sat Dec 21 2013 .SYNOPSIS... A storm system will continue to shift out the Inland Northwest today and tonight...however moist northwest flow will persist. This will keep the threat of light snow or freezing drizzle over the region through the weekend. The best chances for precipitation will occur near the Cascades and over southeast Washington and the central Idaho Panhandle. Another storm will move into the area on Monday, but with milder valley temperatures and less precipitation. Drier weather is expected toward the middle to latter part of next week, including Christmas Day. && .DISCUSSION... Today and Tonight...Yesterdays strong shortwave trough and associated warm front has generally shifted south and east of the region while the strong offshore ridge remains in place. This will keep northwest flow over the area through the day. Satellite imagery not depicting any shortwave disturbances upstream from us at the moment...however low level moisture remains plentiful per the latest fog product. Most of this moisture was present as an extensive blanket of stratus covering much of the forecast area. There was also a mid-level cloud deck covering the southern Idaho Panhandle and SE Washington associated with weak-moderate isentropic ascent. Radar continued to show very light returns in these areas while nearby observations were detecting occasional light precipitation in the form of light snow...and perhaps some freezing drizzle. The HRRR was handling things quite well...and if it performance remains consistent...this precipitation will wane through the morning as it dives south of the forecast area. Consequently we will continue to chip away at the winter highlights. We will remove the Palouse for now...with the others soon to follow. The precipitation should ease out of the Camas Prairie last...and this highlight may need to be extended a couple hours. For tonight...the moist northwest flow continue and a weak shortwave is expected to drop over the northern Cascades this evening and into the Idaho Panhandle later tonight. The isentropic ascent will strengthen ahead of the feature and should produce another round of precipitation. This time...the amount of atmospheric moisture will pale compared to yesterdays event while the dendritic layer saturation and lifting looks unimpressive. Even so...the Cascades will see good chances of precipitation overnight...with an increasing trend for SE Washington and the central Panhandle overnight. Most of the precipitation will fall as light snow...however without a fully saturated dendritic layer...some drizzle or freezing drizzle could also occur. fx Sunday and Sunday Night: Moisture continues to move over the top of the ridge to our west for Sunday before another system gets set to move in Sunday Night into Monday. From current models most of the moisture looks to get hung up in the Cascades leaving much of the Basin essentially dry. It is not until the higher terrain further downstream in the flow pattern that the chance for precipitation once again returns. Given the NW flow pattern this would allow for the Blues and Central Panhandle Mtns to see the best chance for precip. As we move into Sunday Night the pattern becomes more zonal as the next approaching system flattens the ridge putting the Cascades and Panhandle Mtns as the most influential terrain for added topographic forcing and therefore the best chance for precipitation. Isentropic forcing looks weak to moderate so the additional forcing will be necessary. Snow levels will be on the rise throughout the period and can be attributed to warmer air pushing into the region from the SSW. By the time the best moisture arrives Sunday Night into Monday, snow levels will be above most valley locations leading to a valley rain mountain snow event. The one exception would be the far northern valleys which could hold onto cold air long enough to see some snow from the system. Temperatures look to be above normal for most as the warm southerly air pushes into the area. /Fliehman Monday through Friday: Now that we have some snow on the ground, can we keep it around for a White Christmas? Monday`s weather is going to make it tough. A short wave currently south of the Aleutians is forecast to move through the eastern Pacific ridge and into the Pac NW by Monday. All computer models agree that this will set up a strong southwesterly low-level flow, and will push the cold air out of the Inland NW. This will raise snow levels above the valley floors, except for near the Canadian border. Thus, this system will bring valley rain instead of snow. Not a lot mind you. But the real snow-eater is the warm wind with dew points above freezing. Winds will increase on Monday afternoon and continue through the evening as the cold front passes through. After this, drier air will move into the region and snow levels will once again drop to the valley floors. But the high pressure ridge re-develops, closing the door to any more Pacific storms. Typically such a ridge would lead to the development of fog and low clouds. Models agree, but they would suggest that there will be enough flow the push the low clouds around instead of filling in the entire Basin. The only other weather feature of note will be some mid-level moisture spilling over the ridge in the 2nd half of the week. There`s no lifting mechanism, so this should just be confined to a few snow showers over the northern mountains. RJ && .AVIATION... 12Z TAFS: The threat of widespread precipitation has ended over the area for the day...however widespread low clouds remain entrenched over all sites except for MWH. The cloud bases will likely range from 004 to 014 through most of the forecast period so look for MVFR/IFR conditions mainly attributed to cigs. The worst conditions will likely impact PUW as light west winds continue to reinforce the low cigs and fog. All sites should see some subtle improvements during the afternoon...but with fairly strong inversions in place and light winds through the mixed layer this is far from certain. Another disturbance moves into the region after 00z...which should expand the low cloud blanket as well as deliver a small chance of -shsn or -fzdz mainly for PUW and LWS. fx && .PRELIMINARY POINT TEMPS/POPS... Spokane 29 22 33 28 38 26 / 0 20 20 50 70 30 Coeur d`Alene 30 24 35 29 39 29 / 0 20 30 50 80 60 Pullman 32 27 37 31 41 27 / 10 40 30 30 70 50 Lewiston 34 30 40 32 41 29 / 20 40 30 20 30 50 Colville 28 21 31 26 36 25 / 0 10 20 50 70 20 Sandpoint 29 22 32 27 37 27 / 0 30 30 50 80 70 Kellogg 30 26 34 31 38 31 / 20 50 40 50 90 70 Moses Lake 31 19 34 24 42 21 / 0 0 20 10 20 0 Wenatchee 33 24 35 27 41 25 / 10 0 20 20 10 10 Omak 26 19 31 23 35 21 / 0 10 20 20 20 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Winter Storm Warning until 5 AM PST early this morning for Central Panhandle Mountains-Lewis and Southern Nez Perce Counties. Winter Weather Advisory until 5 AM PST early this morning for Lewiston Area. WA...Winter Storm Warning until 5 AM PST early this morning for Northeast Blue Mountains. Winter Weather Advisory until 5 AM PST early this morning for Lower Garfield and Asotin Counties. && $$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
257 AM PST Sat Dec 21 2013 .SYNOPSIS... A storm system will continue to shift out the Inland Northwest today and tonight...however moist northwest flow will persist. This will keep the threat of light snow or freezing drizzle over the region through the weekend. The best chances for precipitation will occur near the Cascades and over southeast Washington and the central Idaho Panhandle. Another storm will move into the area on Monday, but with milder valley temperatures and less precipitation. Drier weather is expected toward the middle to latter part of next week, including Christmas Day. && .DISCUSSION... Today and Tonight...Yesterdays strong shortwave trough and associated warm front has generally shifted south and east of the region while the strong offshore ridge remains in place. This will keep northwest flow over the area through the day. Satellite imagery not depicting any shortwave disturbances upstream from us at the moment...however low level moisture remains plentiful per the latest fog product. Most of this moisture was present as an extensive blanket of stratus covering much of the forecast area. There was also a mid-level cloud deck covering the southern Idaho Panhandle and SE Washington associated with weak-moderate isentropic ascent. Radar continued to show very light returns in these areas while nearby observations were detecting occasional light precipitation in the form of light snow...and perhaps some freezing drizzle. The HRRR was handling things quite well...and if it performance remains consistent...this precipitation will wane through the morning as it dives south of the forecast area. Consequently we will continue to chip away at the winter highlights. We will remove the Palouse for now...with the others soon to follow. The precipitation should ease out of the Camas Prairie last...and this highlight may need to be extended a couple hours. For tonight...the moist northwest flow continue and a weak shortwave is expected to drop over the northern Cascades this evening and into the Idaho Panhandle later tonight. The isentropic ascent will strengthen ahead of the feature and should produce another round of precipitation. This time...the amount of atmospheric moisture will pale compared to yesterdays event while the dendritic layer saturation and lifting looks unimpressive. Even so...the Cascades will see good chances of precipitation overnight...with an increasing trend for SE Washington and the central Panhandle overnight. Most of the precipitation will fall as light snow...however without a fully saturated dendritic layer...some drizzle or freezing drizzle could also occur. fx Sunday and Sunday Night: Moisture continues to move over the top of the ridge to our west for Sunday before another system gets set to move in Sunday Night into Monday. From current models most of the moisture looks to get hung up in the Cascades leaving much of the Basin essentially dry. It is not until the higher terrain further downstream in the flow pattern that the chance for precipitation once again returns. Given the NW flow pattern this would allow for the Blues and Central Panhandle Mtns to see the best chance for precip. As we move into Sunday Night the pattern becomes more zonal as the next approaching system flattens the ridge putting the Cascades and Panhandle Mtns as the most influential terrain for added topographic forcing and therefore the best chance for precipitation. Isentropic forcing looks weak to moderate so the additional forcing will be necessary. Snow levels will be on the rise throughout the period and can be attributed to warmer air pushing into the region from the SSW. By the time the best moisture arrives Sunday Night into Monday, snow levels will be above most valley locations leading to a valley rain mountain snow event. The one exception would be the far northern valleys which could hold onto cold air long enough to see some snow from the system. Temperatures look to be above normal for most as the warm southerly air pushes into the area. /Fliehman Monday through Friday: Now that we have some snow on the ground, can we keep it around for a White Christmas? Monday`s weather is going to make it tough. A short wave currently south of the Aleutians is forecast to move through the eastern Pacific ridge and into the Pac NW by Monday. All computer models agree that this will set up a strong southwesterly low-level flow, and will push the cold air out of the Inland NW. This will raise snow levels above the valley floors, except for near the Canadian border. Thus, this system will bring valley rain instead of snow. Not a lot mind you. But the real snow-eater is the warm wind with dew points above freezing. Winds will increase on Monday afternoon and continue through the evening as the cold front passes through. After this, drier air will move into the region and snow levels will once again drop to the valley floors. But the high pressure ridge re-develops, closing the door to any more Pacific storms. Typically such a ridge would lead to the development of fog and low clouds. Models agree, but they would suggest that there will be enough flow the push the low clouds around instead of filling in the entire Basin. The only other weather feature of note will be some mid-level moisture spilling over the ridge in the 2nd half of the week. There`s no lifting mechanism, so this should just be confined to a few snow showers over the northern mountains. RJ && .AVIATION... 06Z TAFS: A storm system will continue to move through southeast WA and central Idaho tonight into Saturday morning. This passing feature and northwest flow will keep some light snow and/or freezing rain in the region of the KLWS/KPUW TAFs through 10-12Z. Some patchy freezing drizzle is also possible about the KGEG to KCOE corridor. Otherwise look for some low clouds, with IFR/LIFR conditions, including some mist/fog with visibilities occasionally under 2 miles. Some of these are expected to expand toward KEAT through the night too. Conditions are then expected to gradually improve through the day Saturday, with some brief VFR/MVFR conditions in the mid-afternoon, before conditions degrade again after 00-03Z. Additional light snow will be possible Saturday night, though the better chances will hold off until after 06Z Sunday. /J. Cote` && .PRELIMINARY POINT TEMPS/POPS... Spokane 29 22 33 28 38 26 / 0 20 20 50 70 30 Coeur d`Alene 30 24 35 29 39 29 / 0 20 30 50 80 60 Pullman 32 27 37 31 41 27 / 10 40 30 30 70 50 Lewiston 34 30 40 32 41 29 / 20 40 30 20 30 50 Colville 28 21 31 26 36 25 / 0 10 20 50 70 20 Sandpoint 29 22 32 27 37 27 / 0 30 30 50 80 70 Kellogg 30 26 34 31 38 31 / 20 50 40 50 90 70 Moses Lake 31 19 34 24 42 21 / 0 0 20 10 20 0 Wenatchee 33 24 35 27 41 25 / 10 0 20 20 10 10 Omak 26 19 31 23 35 21 / 0 10 20 20 20 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Winter Storm Warning until 5 AM PST early this morning for Central Panhandle Mountains-Lewis and Southern Nez Perce Counties. Winter Weather Advisory until 5 AM PST early this morning for Lewiston Area. WA...Winter Storm Warning until 5 AM PST early this morning for Northeast Blue Mountains. Winter Weather Advisory until 5 AM PST early this morning for Lower Garfield and Asotin Counties. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1118 AM CST SAT DEC 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 343 AM CST SAT DEC 21 2013 CONCENTRATING ON REFINING THE WINTER STORM DETAILS AND IMPACTS IN THE FORECAST SUITE. IN GENERAL...THERE HAVE BEEN MINOR CHANGES TO THE FORECAST FOR THIS STORM...AND IT STILL LOOKS ON TRACK. THIS SYSTEM IS WHY MANY METEOROLOGISTS WENT INTO WEATHER. THE POWER RIGHT NOW FROM THIS SYSTEM IN THE SOUTHERN U.S. IS REMARKABLE. GOES WATER VAPOR CLEARLY SHOWING THE STRONG TROUGH OVER SRN NEW MEXICO WITH STRONG QVECTOR CONVERGENCE AND FORCING OVER WESTERN TEXAS /GREAT TRANSVERSE WAVES ON IR IMAGERY/. SURFACE PRESSURES ARE FALLING IN ARKANSAS ABOUT 1MB/HR...AND THE LOW-LEVEL JET IS INCREASING INTO A FRONTAL ZONE DEFINED BY 34F TO 72F ACROSS NRN AR...AND CONVECTION WITH C-G LIGHTNING. DEWPOINTS IN THE WARM SECTOR ARE IN THE LOWER 70S ILLUSTRATING THE AMOUNT OF MOISTURE DRAWING INTO THIS SYSTEM. THIS STORM HAS ALL THE DYNAMICS FOR A MAJOR PRECIPITATION PRODUCER...STRONG AND COMPACT QVECTOR CONVERGENCE/DIVERGENCE DIPOLE...UPPER LEVEL JET ENTRANCE REGION DIVERGENCE ALOFT /JET MAX OVER SRN CANADA OF 180KTS FORECAST/...STRONG FRONTOGENETIC FORCING AT 600-700MB /GREAT FOR SNOW PRODUCTION/. SO...THE QUESTION IS WHERE WILL THE SNOW BAND LAY DOWN...WITHIN A COUNTY...AND TRYING TO UNDERSTAND WHY THE MODELS ARE STILL DIFFERENT. SINCE 20.12Z...THE NAM HAS REALLY CHANGED ITS TUNE TO A WET AND WEST AND MORE IN-LINE SOLUTION WITH THE GFS/EC/CANADIAN...AND HAS BEEN CONSISTENT WITH ITS OUTCOMES IN THE LAST 3 RUNS. THE HIGHEST PRECIPITATION BAND IS CONSISTENT WITH THE 20.12 ECMWF AND LATEST CANADIAN/GFS RUNS...ROUGHLY FROM KDBQ-KDLL AND SOUTHEAST. THE 21.12Z ECMWF HAS SHIFTED A BIT EAST NOW. OVERALL...THE ECMWF SEEMS TO HAVE THE BEST 500MB DEPICTION INDICATING A STRONG NEARLY CLOSED LOW SHIFTING NORTHEAST...WHILE THE 21.00Z GFS VORTICITY IS DISORGANIZED AND CHANNELED...AND THE GFS SURFACE LOW FURTHEST EAST. WPC MODEL GUIDANCE DISCUSSION PREFERRED AN ECMWF SOLUTION OR NON-NCEP ENSEMBLE. BOTTOM LINE IS THEY ARE ALL VERY REASONABLE ON QPF/SNOW AMOUNTS EXCEPT POSSIBLY THE NAM THAT SEEMS TO SPREAD TOO MUCH PRECIPITATION NORTHWEST...SUGGESTING IMPACTS FURTHER WEST INTO MN/IA...A WIDE ADVISORY SNOW AREA. WHILE THIS SOLUTION CANNOT BE DISCOUNTED...THE NORTHERN STREAM INFLUENCE/DEFORMATION SHOULD LIMITED THE WESTWARD EXTENT....AND THE UPPER JET DIVERGENCE SEEMS TO SUPPORT A MORE WI/IL SOLUTION FOR THE BEST LIFT /EAST/. SNOW FORECAST REMAINS CONSISTENT...BUT HAVE MADE A SLIGHT TWEAK WEST...MAYBE ONE-HALF A COUNTY. THE WARNING IS WELL PLACED...BUT HAVE DECIDED TO INCLUDE JUNEAU AND ADAMS COUNTY IN CENTRAL WI. ALSO HAVE ADDED FAYETTE COUNTY TO THE WARNING AFTER COLLABORATION WITH DMX. HAVE CHANGED THE REMAINING WATCH COUNTIES TO AN ADVISORY AND BASED ON THE 3 INCH SNOW TOTAL LINE...BUILT A FEW OTHER COUNTIES INTO THE ADVISORY WESTWARD. TIMING... LATEST RUNS OF THE RAP INDICATE THE POSSIBILITY OF PRECIPITATION TO THE IL/WI BORDER BY 6 PM TONIGHT. THIS IS A BIT FASTER TREND THAN THE OTHER MODELS WHICH BEGIN SNOW AROUND 8-9PM IN THE SOUTH. EVEN THOUGH CONSENSUS IS FOR ONSET IN THE SOUTH AT 8-9 PM HAVE LEFT THAT START TIME 6 PM FOR NOW. THAT CAN BE ADJUSTED IF NEEDED. HOWEVER...HAVE ADJUSTED START TIME IN CENTRAL WI TO 03Z/9PM FOR THE WARNING...BASICALLY THE I-90 CORRIDOR. THE HEAVIEST SNOW WILL FALL FROM ABOUT 3 AM TO 9 AM. IMPACTS... BECAUSE THIS STORM HAS SHORTER DURATION...WARNING SNOW AMOUNTS WILL NOT BE UNUSUAL IN THE FORECAST AREA WITH 6 TO 8 INCHES EXPECTED AND 2 TO 5 IN THE ADVISORY. WINDS WILL BE STRONGEST IN SERN MN INTO NERN IA...15 TO 25 MPH. THIS LEADS TO THE UPGRADE TO WARNING IN FAYETTE AS A BIT MORE BLOWING IS EXPECTED THERE WITH 4-5 INCHES OF SNOW. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 343 AM CST SAT DEC 21 2013 SNOW SLOWLY DIMINISHES TO FLURRIES OR VERY LIGHT ACCUMULATING SNOW SUNDAY AFTERNOON. HOWEVER...THE NORTHERN STREAM DAKOTAS SHORTWAVE TROUGH WILL BE MOVING IN WITH THE SURGE OF ARCTIC AIR SUNDAY NIGHT. THIS FORCING AND COLD ADVECTION WILL PROVIDE SOME INSTABILITY AND LIFT FOR AN EXTENSION OF LIGHTLY ACCUMULATING SNOW. SUNDAY NIGHT AND MONDAY MORNING COULD BRING ANOTHER 1-2 INCHES OF FLUFFY SNOW...WITH THE 2 INCH AMOUNTS NEAR AND NORTHEAST OF I-94. THIS IS A LARGER CHANGE IN THE FORECAST. AN ACTIVE PATTERN CONTINUES THROUGH THE WEEK WITH WARM ADVECTION SNOWFALL POSSIBLE CHRISTMAS EVE AND ANOTHER VIGOROUS TROUGH POSSIBLY THURSDAY WITH ANOTHER COLD AIR SURGE. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1118 AM CST SAT DEC 21 2013 THERE LOOKS TO BE A GROWING MODEL CONSENSUS BETWEEN THE 21.12Z NAM AND GFS...21.06Z HI-RES ARW AND NMM AND THE 21.09Z SREF MEMBERS THAT THE WORST CONDITIONS FROM THE INCOMING WINTER STORM WILL STAY SOUTHEAST OF BOTH TAF SITES. STILL EXPECT TO SEE SNOW OVERNIGHT INTO SUNDAY MORNING FOR BOTH TAF SITES...BUT CONDITIONS MAY NOT BE A BAD AS PREVIOUSLY EXPECTED. CURRENT CEILINGS ARE EXPECTED TO SLOWLY GO DOWN THROUGH THE AFTERNOON WITH IFR AT BOTH SITES BY MID TO LATE AFTERNOON. LOOK FOR THESE CONDITIONS TO THEN PREVAIL THROUGH THE REST OF THE PERIOD. THE SNOW SHOULD MOVE IN LATE TONIGHT AND IMPACT KLSE THE MOST. THE VISIBILITY WILL GO DOWN TO IFR SHORTLY AFTER THE SNOW BEGINS AND IS EXPECTED TO GO DOWN TO ABOUT A MILE OR SO DURING THE HEAVIEST PERIOD OF SNOW EARLY SUNDAY MORNING. THE SREF WOULD SUGGEST THIS MAY TOO PESSIMISTIC AS IT HAS ALMOST NO SIGNAL FOR VISIBILITIES UNDER A MILE AT KLSE AND ONLY A SMALL SIGNAL FOR LESS THAN 3 MILE VISIBILITIES. THE SNOW WILL START TO SHIFT OFF TO THE EAST LATE SUNDAY MORNING WITH SOME IMPROVEMENT OCCURRING AT KRST. DID NOT SHOW ANY IMPROVEMENT AT KLSE WITH THIS FORECAST AS THE TIMING OF THIS LOOKS TO BE RIGHT AT THE END OF THE FORECAST PERIOD. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR WIZ053. WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR WIZ054-055-061. WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST SUNDAY FOR WIZ034-041-042. WINTER STORM WARNING FROM 9 PM THIS EVENING TO 6 PM CST SUNDAY FOR WIZ043-044. MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR MNZ096. IA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR IAZ010-011-019. WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR IAZ029-030. && $$ SHORT TERM...BAUMGARDT LONG TERM...BAUMGARDT AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
524 AM CST SAT DEC 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 343 AM CST SAT DEC 21 2013 CONCENTRATING ON REFINING THE WINTER STORM DETAILS AND IMPACTS IN THE FORECAST SUITE. IN GENERAL...THERE HAVE BEEN MINOR CHANGES TO THE FORECAST FOR THIS STORM...AND IT STILL LOOKS ON TRACK. THIS SYSTEM IS WHY MANY METEOROLOGISTS WENT INTO WEATHER. THE POWER RIGHT NOW FROM THIS SYSTEM IN THE SOUTHERN U.S. IS REMARKABLE. GOES WATER VAPOR CLEARLY SHOWING THE STRONG TROUGH OVER SRN NEW MEXICO WITH STRONG QVECTOR CONVERGENCE AND FORCING OVER WESTERN TEXAS /GREAT TRANSVERSE WAVES ON IR IMAGERY/. SURFACE PRESSURES ARE FALLING IN ARKANSAS ABOUT 1MB/HR...AND THE LOW-LEVEL JET IS INCREASING INTO A FRONTAL ZONE DEFINED BY 34F TO 72F ACROSS NRN AR...AND CONVECTION WITH C-G LIGHTNING. DEWPOINTS IN THE WARM SECTOR ARE IN THE LOWER 70S ILLUSTRATING THE AMOUNT OF MOISTURE DRAWING INTO THIS SYSTEM. THIS STORM HAS ALL THE DYNAMICS FOR A MAJOR PRECIPITATION PRODUCER...STRONG AND COMPACT QVECTOR CONVERGENCE/DIVERGENCE DIPOLE...UPPER LEVEL JET ENTRANCE REGION DIVERGENCE ALOFT /JET MAX OVER SRN CANADA OF 180KTS FORECAST/...STRONG FRONTOGENETIC FORCING AT 600-700MB /GREAT FOR SNOW PRODUCTION/. SO...THE QUESTION IS WHERE WILL THE SNOW BAND LAY DOWN...WITHIN A COUNTY...AND TRYING TO UNDERSTAND WHY THE MODELS ARE STILL DIFFERENT. SINCE 20.12Z...THE NAM HAS REALLY CHANGED ITS TUNE TO A WET AND WEST AND MORE IN-LINE SOLUTION WITH THE GFS/EC/CANADIAN...AND HAS BEEN CONSISTENT WITH ITS OUTCOMES IN THE LAST 3 RUNS. THE HIGHEST PRECIPITATION BAND IS CONSISTENT WITH THE 20.12 ECMWF AND LATEST CANADIAN/GFS RUNS...ROUGHLY FROM KDBQ-KDLL AND SOUTHEAST. THE 21.12Z ECMWF HAS SHIFTED A BIT EAST NOW. OVERALL...THE ECMWF SEEMS TO HAVE THE BEST 500MB DEPICTION INDICATING A STRONG NEARLY CLOSED LOW SHIFTING NORTHEAST...WHILE THE 21.00Z GFS VORTICITY IS DISORGANIZED AND CHANNELED...AND THE GFS SURFACE LOW FURTHEST EAST. WPC MODEL GUIDANCE DISCUSSION PREFERRED AN ECMWF SOLUTION OR NON-NCEP ENSEMBLE. BOTTOM LINE IS THEY ARE ALL VERY REASONABLE ON QPF/SNOW AMOUNTS EXCEPT POSSIBLY THE NAM THAT SEEMS TO SPREAD TOO MUCH PRECIPITATION NORTHWEST...SUGGESTING IMPACTS FURTHER WEST INTO MN/IA...A WIDE ADVISORY SNOW AREA. WHILE THIS SOLUTION CANNOT BE DISCOUNTED...THE NORTHERN STREAM INFLUENCE/DEFORMATION SHOULD LIMITED THE WESTWARD EXTENT....AND THE UPPER JET DIVERGENCE SEEMS TO SUPPORT A MORE WI/IL SOLUTION FOR THE BEST LIFT /EAST/. SNOW FORECAST REMAINS CONSISTENT...BUT HAVE MADE A SLIGHT TWEAK WEST...MAYBE ONE-HALF A COUNTY. THE WARNING IS WELL PLACED...BUT HAVE DECIDED TO INCLUDE JUNEAU AND ADAMS COUNTY IN CENTRAL WI. ALSO HAVE ADDED FAYETTE COUNTY TO THE WARNING AFTER COLLABORATION WITH DMX. HAVE CHANGED THE REMAINING WATCH COUNTIES TO AN ADVISORY AND BASED ON THE 3 INCH SNOW TOTAL LINE...BUILT A FEW OTHER COUNTIES INTO THE ADVISORY WESTWARD. TIMING... LATEST RUNS OF THE RAP INDICATE THE POSSIBILITY OF PRECIPITATION TO THE IL/WI BORDER BY 6 PM TONIGHT. THIS IS A BIT FASTER TREND THAN THE OTHER MODELS WHICH BEGIN SNOW AROUND 8-9PM IN THE SOUTH. EVEN THOUGH CONSENSUS IS FOR ONSET IN THE SOUTH AT 8-9 PM HAVE LEFT THAT START TIME 6 PM FOR NOW. THAT CAN BE ADJUSTED IF NEEDED. HOWEVER...HAVE ADJUSTED START TIME IN CENTRAL WI TO 03Z/9PM FOR THE WARNING...BASICALLY THE I-90 CORRIDOR. THE HEAVIEST SNOW WILL FALL FROM ABOUT 3 AM TO 9 AM. IMPACTS... BECAUSE THIS STORM HAS SHORTER DURATION...WARNING SNOW AMOUNTS WILL NOT BE UNUSUAL IN THE FORECAST AREA WITH 6 TO 8 INCHES EXPECTED AND 2 TO 5 IN THE ADVISORY. WINDS WILL BE STRONGEST IN SERN MN INTO NERN IA...15 TO 25 MPH. THIS LEADS TO THE UPGRADE TO WARNING IN FAYETTE AS A BIT MORE BLOWING IS EXPECTED THERE WITH 4-5 INCHES OF SNOW. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 343 AM CST SAT DEC 21 2013 SNOW SLOWLY DIMINISHES TO FLURRIES OR VERY LIGHT ACCUMULATING SNOW SUNDAY AFTERNOON. HOWEVER...THE NORTHERN STREAM DAKOTAS SHORTWAVE TROUGH WILL BE MOVING IN WITH THE SURGE OF ARCTIC AIR SUNDAY NIGHT. THIS FORCING AND COLD ADVECTION WILL PROVIDE SOME INSTABILITY AND LIFT FOR AN EXTENSION OF LIGHTLY ACCUMULATING SNOW. SUNDAY NIGHT AND MONDAY MORNING COULD BRING ANOTHER 1-2 INCHES OF FLUFFY SNOW...WITH THE 2 INCH AMOUNTS NEAR AND NORTHEAST OF I-94. THIS IS A LARGER CHANGE IN THE FORECAST. AN ACTIVE PATTERN CONTINUES THROUGH THE WEEK WITH WARM ADVECTION SNOWFALL POSSIBLE CHRISTMAS EVE AND ANOTHER VIGOROUS TROUGH POSSIBLY THURSDAY WITH ANOTHER COLD AIR SURGE. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 524 AM CST SAT DEC 21 2013 IFR/MVFR CLOUD COVER WILL CONTINUE THROUGH TODAY. ATTENTION THEN TURNS TO A POTENT LOW PRESSURE SYSTEM LIFTING OUT OF THE SOUTHERN PLAINS INTO THE GREAT LAKES REGION TONIGHT THROUGH SUNDAY. SNOW IS EXPECTED TO SPREAD INTO NORTHEAST IA/SOUTHERN WI THIS EVENING AND THEN INTO THE KLSE/KRST TAF SITES AFTER 07Z/09Z RESPECTIVELY. DUE TO THE TRACK OF THE STORM SYSTEM...KLSE LOOKS TO BE IMPACTED BY MODERATE SNOWFALL SNOW AT TIMES AFTER 10Z WITH TEMPORARY LIFR VSBY/CIG CONDITIONS THROUGH MID-SUNDAY MORNING. LIGHTER SNOWFALL WILL BE SEEN AT KRST AS A RESULT OF BEING FARTHER NORTHWEST OF THE TRACK OF THE LOW...BUT REMAINING IN IFR CONDITIONS. RIGHT NOW...IT APPEARS AROUND 3 INCHES OF SNOWFALL IS LIKELY TONIGHT THROUGH SUNDAY AT KLSE WITH 1 TO 1.5 INCHES LIKELY AT KRST. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR WIZ053. WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR WIZ054-055-061. WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST SUNDAY FOR WIZ034-041-042. WINTER STORM WARNING FROM 9 PM THIS EVENING TO 6 PM CST SUNDAY FOR WIZ043-044. MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR MNZ096. IA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR IAZ010-011-019. WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR IAZ029-030. && $$ SHORT TERM...BAUMGARDT LONG TERM...BAUMGARDT AVIATION...DAS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
343 AM CST SAT DEC 21 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 343 AM CST SAT DEC 21 2013 CONCENTRATING ON REFINING THE WINTER STORM DETAILS AND IMPACTS IN THE FORECAST SUITE. IN GENERAL...THERE HAVE BEEN MINOR CHANGES TO THE FORECAST FOR THIS STORM...AND IT STILL LOOKS ON TRACK. THIS SYSTEM IS WHY MANY METEOROLOGISTS WENT INTO WEATHER. THE POWER RIGHT NOW FROM THIS SYSTEM IN THE SOUTHERN U.S. IS REMARKABLE. GOES WATER VAPOR CLEARLY SHOWING THE STRONG TROUGH OVER SRN NEW MEXICO WITH STRONG QVECTOR CONVERGENCE AND FORCING OVER WESTERN TEXAS /GREAT TRANSVERSE WAVES ON IR IMAGERY/. SURFACE PRESSURES ARE FALLING IN ARKANSAS ABOUT 1MB/HR...AND THE LOW-LEVEL JET IS INCREASING INTO A FRONTAL ZONE DEFINED BY 34F TO 72F ACROSS NRN AR...AND CONVECTION WITH C-G LIGHTNING. DEWPOINTS IN THE WARM SECTOR ARE IN THE LOWER 70S ILLUSTRATING THE AMOUNT OF MOISTURE DRAWING INTO THIS SYSTEM. THIS STORM HAS ALL THE DYNAMICS FOR A MAJOR PRECIPITATION PRODUCER...STRONG AND COMPACT QVECTOR CONVERGENCE/DIVERGENCE DIPOLE...UPPER LEVEL JET ENTRANCE REGION DIVERGENCE ALOFT /JET MAX OVER SRN CANADA OF 180KTS FORECAST/...STRONG FRONTOGENETIC FORCING AT 600-700MB /GREAT FOR SNOW PRODUCTION/. SO...THE QUESTION IS WHERE WILL THE SNOW BAND LAY DOWN...WITHIN A COUNTY...AND TRYING TO UNDERSTAND WHY THE MODELS ARE STILL DIFFERENT. SINCE 20.12Z...THE NAM HAS REALLY CHANGED ITS TUNE TO A WET AND WEST AND MORE IN-LINE SOLUTION WITH THE GFS/EC/CANADIAN...AND HAS BEEN CONSISTENT WITH ITS OUTCOMES IN THE LAST 3 RUNS. THE HIGHEST PRECIPITATION BAND IS CONSISTENT WITH THE 20.12 ECMWF AND LATEST CANADIAN/GFS RUNS...ROUGHLY FROM KDBQ-KDLL AND SOUTHEAST. THE 21.12Z ECMWF HAS SHIFTED A BIT EAST NOW. OVERALL...THE ECMWF SEEMS TO HAVE THE BEST 500MB DEPICTION INDICATING A STRONG NEARLY CLOSED LOW SHIFTING NORTHEAST...WHILE THE 21.00Z GFS VORTICITY IS DISORGANIZED AND CHANNELED...AND THE GFS SURFACE LOW FURTHEST EAST. WPC MODEL GUIDANCE DISCUSSION PREFERRED AN ECMWF SOLUTION OR NON-NCEP ENSEMBLE. BOTTOM LINE IS THEY ARE ALL VERY REASONABLE ON QPF/SNOW AMOUNTS EXCEPT POSSIBLY THE NAM THAT SEEMS TO SPREAD TOO MUCH PRECIPITATION NORTHWEST...SUGGESTING IMPACTS FURTHER WEST INTO MN/IA...A WIDE ADVISORY SNOW AREA. WHILE THIS SOLUTION CANNOT BE DISCOUNTED...THE NORTHERN STREAM INFLUENCE/DEFORMATION SHOULD LIMITED THE WESTWARD EXTENT....AND THE UPPER JET DIVERGENCE SEEMS TO SUPPORT A MORE WI/IL SOLUTION FOR THE BEST LIFT /EAST/. SNOW FORECAST REMAINS CONSISTENT...BUT HAVE MADE A SLIGHT TWEAK WEST...MAYBE ONE-HALF A COUNTY. THE WARNING IS WELL PLACED...BUT HAVE DECIDED TO INCLUDE JUNEAU AND ADAMS COUNTY IN CENTRAL WI. ALSO HAVE ADDED FAYETTE COUNTY TO THE WARNING AFTER COLLABORATION WITH DMX. HAVE CHANGED THE REMAINING WATCH COUNTIES TO AN ADVISORY AND BASED ON THE 3 INCH SNOW TOTAL LINE...BUILT A FEW OTHER COUNTIES INTO THE ADVISORY WESTWARD. TIMING... LATEST RUNS OF THE RAP INDICATE THE POSSIBILITY OF PRECIPITATION TO THE IL/WI BORDER BY 6 PM TONIGHT. THIS IS A BIT FASTER TREND THAN THE OTHER MODELS WHICH BEGIN SNOW AROUND 8-9PM IN THE SOUTH. EVEN THOUGH CONSENSUS IS FOR ONSET IN THE SOUTH AT 8-9 PM HAVE LEFT THAT START TIME 6 PM FOR NOW. THAT CAN BE ADJUSTED IF NEEDED. HOWEVER...HAVE ADJUSTED START TIME IN CENTRAL WI TO 03Z/9PM FOR THE WARNING...BASICALLY THE I-90 CORRIDOR. THE HEAVIEST SNOW WILL FALL FROM ABOUT 3 AM TO 9 AM. IMPACTS... BECAUSE THIS STORM HAS SHORTER DURATION...WARNING SNOW AMOUNTS WILL NOT BE UNUSUAL IN THE FORECAST AREA WITH 6 TO 8 INCHES EXPECTED AND 2 TO 5 IN THE ADVISORY. WINDS WILL BE STRONGEST IN SERN MN INTO NERN IA...15 TO 25 MPH. THIS LEADS TO THE UPGRADE TO WARNING IN FAYETTE AS A BIT MORE BLOWING IS EXPECTED THERE WITH 4-5 INCHES OF SNOW. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 343 AM CST SAT DEC 21 2013 SNOW SLOWLY DIMINISHES TO FLURRIES OR VERY LIGHT ACCUMULATING SNOW SUNDAY AFTERNOON. HOWEVER...THE NORTHERN STREAM DAKOTAS SHORTWAVE TROUGH WILL BE MOVING IN WITH THE SURGE OF ARCTIC AIR SUNDAY NIGHT. THIS FORCING AND COLD ADVECTION WILL PROVIDE SOME INSTABILITY AND LIFT FOR AN EXTENSION OF LIGHTLY ACCUMULATING SNOW. SUNDAY NIGHT AND MONDAY MORNING COULD BRING ANOTHER 1-2 INCHES OF FLUFFY SNOW...WITH THE 2 INCH AMOUNTS NEAR AND NORTHEAST OF I-94. THIS IS A LARGER CHANGE IN THE FORECAST. AN ACTIVE PATTERN CONTINUES THROUGH THE WEEK WITH WARM ADVECTION SNOWFALL POSSIBLE CHRISTMAS EVE AND ANOTHER VIGOROUS TROUGH POSSIBLY THURSDAY WITH ANOTHER COLD AIR SURGE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1140 PM CST FRI DEC 20 2013 MVFR TO IFR CEILINGS WILL LINGER THROUGH TOMORROW AS ONE LOW PRESSURE SYSTEM TRACKS TO THE EAST IN THE GREAT LAKES WHILE A SECOND...MORE POTENT LOW IS DEVELOPING IN THE SOUTHERN PLAINS. THIS SECOND LOW WILL BRING SNOW INTO THE REGION OVERNIGHT ON SATURDAY...BUT NOT UNTIL AFTER THE END OF THIS TAF PERIOD. WHILE CONDITIONS MAY BRIEFLY IMPROVE ON SATURDAY...THEY SHOULD DROP AGAIN SATURDAY NIGHT AS LOW LEVEL MOISTURE INCREASES ACROSS THE REGION. WINDS WILL REMAIN LIGHT THROUGH MUCH OF THE DAY BEFORE GOING NORTHEAST AND INCREASING TO AROUND 10-15KTS SATURDAY NIGHT. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR WIZ053. WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR WIZ054-055-061. WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST SUNDAY FOR WIZ034-041-042. WINTER STORM WARNING FROM 9 PM THIS EVENING TO 6 PM CST SUNDAY FOR WIZ043-044. MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR MNZ096. IA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR IAZ010-011-019. WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY FOR IAZ029-030. && $$ SHORT TERM...BAUMGARDT LONG TERM...BAUMGARDT AVIATION...HALBACH
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
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
  [top] 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 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
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
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
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
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 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
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 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 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 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 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 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 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 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 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 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 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...