Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 01/08/13


AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
921 PM PST SAT JAN 5 2013 .SHORT TERM DISCUSSION... SATELLITE IMAGERY SHOWED A ELONGATED SPLITTING TROUGH ALIGNED ALONG THE PACIFIC COASTLINE FROM THE GULF OF ALASKA TO SAN FRANCISCO EARLIER THIS EVENING. LATEST WATER VAPOR LOOP SHOWS THAT ENERGY ROUNDING THE BASE OF THIS TROUGH HAS BEGUN TO DECOUPLE FROM THE MEAN WESTERLY JET AND IS SHOWING SIGNS THAT IT IS FORMING A 550MB CLOSED LOW LESS THAN A HUNDRED MILES OFFSHORE OF THE BAY AREA. THE BROAD TRANSITIONAL NATURE OF THIS SYSTEM LEAD TO RELATIVELY WEAK DIFFERENTIAL FORCING/ISENTROPIC LIFT THUS FAR. THE RESULT OF THIS IS A WIDESPREAD ALBEIT LIGHT PRECIPITATION EVENT. THIS IS EVIDENT BY AREAL RAIN GAGES REPORTING LESS THAN A TENTH OF RAIN WITH ONLY A SELECT FEW BREACHING THE QUARTER INCH MARK THIS EVENING. RADAR IMAGERY SHOWS WIDESPREAD LOW REFLECTIVITIES INDICATIVE OF LIGHT PRECIPITATION WITH THE EXCEPTION OF AN AREA OF HEAVIER RAIN/GRAUPEL ON THE WESTERN PERIPHERY OF THE CENTRAL SAC VALLEY. KRDD STRUGGLING TO SECURE A TRACE OF RAIN SO FAR. THE UPPER LEVEL SYSTEMS ARRIVAL HAS HASTENED SINCE THE LAST SHORT TERM MODELS WERE INITIALIZED. THE SREF...NAM...AND HRRR MODELS ARE ALL LAGGING REALITY BY ABOUT 3 HOURS PER LATEST RADAR IMAGERY. DESPITE THIS... WOULD AGREE WITH THE SHORT TERM MODELS SCALING BACK PRECIP OVER THE NORTHERN SAC VALLEY/SOUTHERN CASCADES TONIGHT AND TOMORROW MORNING. DECIDED TO SCALE BACK PRECIP COVERAGE AND PROBABILITY OVER THE NEXT 72 HRS AND SENT OUT A FORECAST UPDATE. SNOW LEVELS OVER THE COASTAL RANGE ARE DROPPING AS A RESULT OF COLD POST FROPA AIR MOVING INTO THE REGION. INITIALLY ABOVE 4500FT... WEBCAMS HAVE SHOWN THE SNOW LEVEL TO BE BETWEEN 2500FT AND 3000FT IN LAKE COUNTY. EXPECT A FURTHER DROP OVERNIGHT. REMAINDER OF AFTERNOON FORECAST PACKAGE ON TRACK. .PREVIOUS DISCUSSION... UPPER LOW APPROACHING THE WEST COAST WILL DISPLACE THE HIGH THAT HAS BEEN OVER THE AREA THE PAST FEW DAYS. ENERGY DROPPING THROUGH THE TROUGH WILL CAUSE AN UPPER LOW TO SPLIT FROM THE TROUGH NEAR THE BAY AREA TONIGHT. RAIN WILL SPREAD INTO THE VALLEY THIS EVENING...AFTER 6 PM FOR MOST AREAS. SNOW LEVELS WILL START OUT NEAR 5000 FEET OVER THE SIERRA AND 3000 FEET FOR THE COASTAL RANGE AND SHASTA COUNTY. LEVELS WILL FALL TO 4000 FEET FOR THE SIERRA AND 2500 FEET FARTHER NORTH SUNDAY MORNING. SNOWFALL WILL BE LIGHT WITH THIS SYSTEM...AS THE BEST MOISTURE AND DYNAMICS WILL BE OVER THE SOUTHERN SIERRA AND SOCAL. EXPECT 2 TO 4 INCHES OVER THE COASTAL RANGE AND SIERRA DURING THE NEXT 24 HRS. HAVE RAISED OVERNIGHT POPS AND ALSO ADJUSTED FOR EARLIER TIMING...AS SYSTEM IS A FEW HOURS AHEAD OF SCHEDULE. THIS LINES UP NICELY WITH RUC/HRRR WHICH BEGIN PRECIP OVER THE COASTAL RANGE AROUND 4 PM AND SAC/SAN JOAQUIN VALLEY AROUND 6 PM. PRECIP WILL BE SLOWER TO SPREAD INTO THE SIERRA WHERE A DRIER ATMOSPHERE EXIST...ACCUMULATING SNOW THERE WILL NOT START UNTIL AFTER MIDNIGHT. UPPER LOW WILL DROP SOUTH OVER SOCAL ON SUNDAY. PRECIP WILL DIMINISH FROM NORTHWEST TO SOUTHEAST DURING THE DAY. ALTHOUGH...STILL REMAIN IN THE LIKELY CATEGORY OVER THE SIERRA SOUTH OF I-80. FOG COULD BE A CONCERN SUNDAY NIGHT IF SKIES CLEAR...BUT AT THIS TIME WILL KEEP THE CLOUDS OVER THE AREA. DISTURBANCE AND MOISTURE PLUME OVER WASHINGTON AND OREGON ON MONDAY WILL BRUSH NORTHERN AREAS AND WILL KEEP SHOWER CHANCES GOING FOR SHASTA COUNTY AND THE COASTAL RANGE. HEIGHT RISES AHEAD OF THIS SYSTEM WILL LEAD TO WARMER TEMPERATURES WITH HIGHS GENERALLY FROM 55 TO 60. RIDGE WILL STRENGTHEN OVER NORCAL ON TUESDAY PUSHING SHOWER CHANCES NORTH OF THE AREA. TEMPERATURES WILL BE FROM THE MID 50`S TO LOWERS 60`S FOR VALLEYS. .EXTENDED DISCUSSION (WEDNESDAY THROUGH SATURDAY) SLIGHT CHANCE TO CHANCE OF PRECIP ACROSS NORCAL WED & THURS AS A TROUGH OVER THE PAC NW DEEPENS INTO OUR REGION. SNOW LEVELS COULD LOWER INTO THE FOOTHILLS ALTHOUGH MODELS INDICATE THAT ANY SNOWFALL WOULD BE LIGHT AT THE LOWER ELEVATIONS. THE TROUGH AXIS MOVES INTO THE GREAT BASIN REGION BY FRIDAY AND BREEZY NORTH TO NORTHEAST FLOW WILL DEVELOP IN OUR CWA BEHIND THE TROUGH. FRIDAY AND SATURDAY WILL BE DRIER WITH THE NORTHERLY FLOW BUT SOME LIGHT SHOWERS MAY STILL AFFECT THE NORTHERN MOUNTAINS AND SHASTA COUNTY. OVERNIGHT LOWS WILL BE BELOW NORMAL WITH DAYTIME HIGHS AT OR SLIGHTLY BELOW NORMAL. IT SHOULD BE NOTED THAT THE ECMWF MODEL IS A BIT OF AN OUTLIER IN THE EXTENDED AS IT DIFFERS FROM THE GEM & GFS (THE PATTERN MENTIONED ABOVE) IN TRACK AND TIMING. JBB && .AVIATION... VFR/MVFR CONDITIONS AND AREAS OF IFR/LIFR CONDITIONS IN THE VALLEY WITH AN UPPER LEVEL LOW MOVING INTO THE AREA TONIGHT BRINGING SHOWERS. IFR/LIFR CONDITIONS EXPECTED IN THE MOUNTAINS OVERNIGHT INTO SUNDAY WITH SNOW LEVELS AROUND 3000 TO 4000 FT. SWLY WIND GUSTS UP TO 40 KTS NEAR SIERRA RIDGES. PRECIPITATION EXPECTED TO DIMINISH FROM NORTH TO SOUTH SUNDAY AFTERNOON AND EVENING. && .STO WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1004 PM MST SAT JAN 5 2013 .AVIATION... VFR CONDITIONS ARE EXPECTED TO CONTINUE OVER THE KCOS AND KPUB TAF SITES THROUGH SUNDAY. AT ALS...THE POTENTIAL FOR LIFR CONDITIONS IS STILL ANTICIPATED AT TIMES LATER TONIGHT DUE TO CIGS AND VIS ASSOCIATED WITH FZFG...THEN VFR CONDITIONS SHOULD RETURN TO KALS...ESPECIALLY AFT 16Z SUNDAY. && .PREV DISCUSSION... /ISSUED 249 PM MST SAT JAN 5 2013/ SHORT TERM... (TONIGHT AND SUNDAY) SHORTWAVE PASSING OFF TO THE NORTHEAST HAS SENT A DRY COLD FRONT THROUGH THE SE PLAINS. WINDS NOT TERRIBLY STRONG WITH IT...AND MIXING HAS ACTUALLY WARMED TEMPS A FEW DEGREES IN SPITE OF THE CAA BEHIND THE FRONT...WITH KLAA AT 45 DEGREES SO FAR...COMPARED TO YESTERDAY`S HIGH OF ONLY 39. MEANWHILE...THE SAN LUIS VALLEY HAS BEEN STRUGGLING TO WARM...WITH KALS ONLY AT 11 DEGREES AS OF 21Z. TONIGHT...CLEAR SKIES...DRY SFC DEW POINTS...AND SNOW COVER IN SOME PLACES WILL LEAD TO ANOTHER COLD NIGHT. CAN`T FIND A REASON WHY KALS WON`T DROP TO AROUND -30 AGAIN TONIGHT...SO TOOK MIN TEMPS THERE WELL BELOW GUIDANCE. OTHER CHALLENGE WILL BE POTENTIAL FOR FOG IN THE SAN LUIS VALLEY. THIS DIDN`T HAPPEN LAST NIGHT...OR AT LEAST VISIBILITY AT KALS DIDN`T DROP BELOW 5 MILES...THOUGH WE DID SEE SOME LIFR STRATUS IN THE WEB CAMS AND IN THE CEILOMETER DATA FROM ASOS. NAM12 SOUNDINGS SATURATE AT THE SFC AROUND 02Z AND REMAIN SO THROUGH 15Z SUN. THE LOCAL 4 KM WRF ALSO INDICATES POTENTIAL FOR FOG...AND HRRR SHOWS SFC RHS APPROACHING 80% BY 09Z SUN. RAP SOUNDINGS BY CONTRAST LOOK FAIRLY DRY...AND NEITHER THE MET NOR MAV GUIDANCE HAVE ANY INDICATION OF FOG. WILL THROW PATCHY FOG INTO THE GRIDS FOR NOW...BUT WILL DELAY THIS UNTIL AFTER 06Z. HUNCH IS IT WON`T OCCUR UNTIL AFTER 09-10Z BASED ON WHAT HAPPENED LAST NIGHT...AND SHOULD BREAK BY 15-16Z ON SUN. FLOW ALOFT BECOMES MORE SOUTHWESTERLY ON SUNDAY AS THE UPPER RIDGE SHIFTS EASTWARD AND NEXT UPPER LOW MOVES INTO CA. LEE TROF DEEPENS IN RESPONSE WITH WINDS AIDING IN BETTER MIXING ALONG THE I-25 CORRIDOR. CURRENT FORECAST WITH 40S AND LOWER 50S LOOK REASONABLE ACROSS THE PLAINS. MEANWHILE...DRY CONDITIONS WILL CONTINUE EVERYWHERE. ITS POSSIBLE THAT KALS COULD SEE SOME MODERATING TEMPERATURES AS WELL IF WINDS CAN MIX IN...BUT GIVEN THE STRONG INVERSIONS...KEPT TEMPS BELOW GUIDANCE VALUES WITH SOME MINOR IMPROVEMENT. -KT LONG TERM... (SUNDAY NIGHT-SATURDAY) SUNDAY NIGHT-MONDAY...LATEST MODELS CONTINUE TO BE IN GOOD AGREEMENT OF DEVELOPING SPLIT FLOW PATTERN INTO THE MIDDLE WEEK. CLOSED LOW IN THE DEVELOPING SOUTHERN STREAM ACROSS THE SOUTHEASTERN NEVADA SUNDAY AFTERNOON PROGGED TO DIVE INTO OLD MEXICO THROUGH THE DAY MONDAY AS A MINOR WAVE EMBEDDED IN THE ZONAL FLOW ACROSS NORTHERN TIER OF STATES TRANSLATES ACROSS THE NORTHERN ROCKIES AND INTO THE NORTHERN HIGH PLAINS. OVERNIGHT LOWS...ESPECIALLY IN THE SAN LUIS VALLEY REMAIN TRICKY WITH SOME INCREASE IN HIGH LEVEL MOISTURE SPREADING ACROSS THE REGION...THOUGH DOES NOT LOOK TO BE ENOUGH TO KEEP TEMPS FROM TANKING...AND HAVE GONE BELOW GUIDANCE VALUES IN THE HIGH MT VALLEYS. BOTH SYSTEMS REMAIN TOO FAR AWAY FROM THE AREA TO PRODUCE ANY PRECIPITATION...THOUGH WILL SEE SLIGHTLY COOLER TEMPERATURES AS PASSING NORTHERN STREAM SYSTEM SENDS A WEAK BACKDOOR COLD FRONT ACROSS EASTERN COLORADO MONDAY MORNING. MONDAY NIGHT-WEDNESDAY NIGHT...WEAK FLOW PROGGED ACROSS THE AREA THROUGH THIS PERIOD AS OLD MEXICO LOW SLOWLY LIFTS OUT INTO THE SOUTHERN HIGH PLAINS. MODELS DIFFER ON TRACK WITH THE EC A TAD FURTHER NORTH AND WEST WITH SAID SYSTEM ACROSS THE NORTH CENTRAL TEXAS PANHANDLE WEDNESDAY NIGHT AND PRINTS OUT SOME LIGHT QPF ACROSS THE FAR SE PLAINS. WITH THE WEAK FLOW ALOFT...HAVE GONE BELOW GUIDANCE FOR HIGHS THROUGH THE PERIOD...WITH TEMPERATURES MAINLY IN THE 40S TO LOWER 50S ACROSS THE PLAINS AND 30S ACROSS THE HIGHER TERRAIN. AGAIN...HAVE STAYED WELL BELOW GUIDANCE FOR THE SAN LUIS VALLEY AS NOT ENOUGH WIND TO SCOUR OUT THE COLD AIRMASS IN PLACE. THURSDAY-SATURDAY...LATEST MODELS CONTINUE TO INDICATE A BETTER CHANCE OF WIDESPREAD PRECIPITATION INTO THE EARLY WEEKEND AS PACIFIC ENERGY DIGGING INTO THE GREAT BASIN ON THURSDAY SLOWLY LIFTS OUT ACROSS THE ROCKIES THROUGH SATURDAY. SOME CONCERN THAT STRONG BACKSIDE JET ACROSS THE GREAT BASIN COULD DIG THE SYSTEM FURTHER SOUTH THAN CURRENT PROJECTIONS...SO HAVE KEPT CURRENT MODEL CONSENSUS SOLUTION WHICH GIVES CHANCE POPS ACROSS THE CONTINENTAL DIVIDE THURSDAY NIGHT AND FRIDAY...WITH CHANCE AND SLIGHT CHANCE POPS SPREADING ACROSS THE REST OF THE HIGHER TERRAIN THROUGH THE EASTERN PLAINS FRIDAY THROUGH SATURDAY. TEMPERATURES WILL ALSO BE TRENDING BACK BELOW SEASONAL AVERAGES BY FRIDAY AND SATURDAY. -MW AVIATION... CLEAR SKIES AND VFR CONDITIONS EXPECTED AT KPUB AND KCOS THROUGH SUNDAY. CHALLENGE WILL BE THE POTENTIAL FOR LIFR CIGS AND POSSIBLY VIS IN FZFG AT KALS OVERNIGHT. MODELS DIFFER IN WHETHER THIS WILL OR WILL NOT OCCUR...AND CONFIDENCE IS LOW. PLAN TO DELAY LIFR CONDITIONS UNTIL AFTER 09Z IN NEXT TAF ISSUANCE. ANY LIFR CIGS/VIS SHOULD BREAK BETWEEN 15-16Z...WITH VFR CONDITIONS AND LIGHT WINDS THROUGH SUNDAY. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS ALBANY NY
1230 AM EST SUN JAN 6 2013 .SYNOPSIS... HIGH PRESSURE OVER THE REGION THIS EVENING...WILL SLIDE OFF THE ATLANTIC SEABOARD LATER TONIGHT. LOW PRESSURE AND ITS ASSOCIATED COLD FRONT TRACKING EAST FROM THE GREAT LAKES WILL MOVE THROUGH OUR REGION LATE TONIGHT THROUGH SUNDAY NIGHT. THIS COULD BRING PERIODS OF LIGHT SNOW OR SNOW SHOWERS...WITH THE BEST CHANCE FOR ACCUMULATIONS IN THE HIGHER TERRAIN. DRIER AND MILDER WEATHER IS EXPECTED THROUGH THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY NIGHT/... AS OF MIDNIGHT...REGIONAL RADAR RETURNS REVEAL AN INCREASING TREND OF PRECIPITATION EVOLVING AS WEAK WARM ADVECTION AND ISENTROPIC LIFT IS UNDERWAY. HRRR EXPERIMENTAL REFLECTIVITIES SUGGEST THIS BAND OF LIGHT SNOW/-SHSN WILL OVERSPREAD THE ENTIRE REGION BY 09Z AND HAVE INCREASED POPS TO 30% FOR THE OVERNIGHT PERIOD. THERE IS A NOTABLE DRY SLOT UPSTREAM OVER THE OHIO VALLEY THAT WILL ADVANCE NORTHEAST TOWARD SUNRISE. THIS SHOULD REDUCE COVERAGE OF PRECIP THROUGH MOST OF THE DAYLIGHT HOURS ON SUNDAY WITH PERHAPS FLURRIES FOR MOST LOCATIONS. THE LAKE ONTARIO CONTRIBUTION DOES NOT APPEAR TO BE OCCURRING ON SUNDAY AS PREVIOUSLY THOUGHT AND MAY HAVE TO REDUCE ACCUMULATIONS WITH THE NEXT UPDATE. AS FOR TEMPERATURES...WE HAVE NOW STEADY THOSE VALUES WITH A SLOWLY RISE EXPECTED THE REMAINDER OF THE OVERNIGHT PERIOD WHICH WILL CONTINUE INTO SUNDAY AFTERNOON. COLD FRONT AND UPPER TROUGH IS STILL SCHEDULED TO MOVE ACROSS THE REGION TONIGHT...WITH TRENDS TOWARD A FASTER AND A SOMEWHAT DRIER SOLUTION. NOT SO DOWNWIND OF LAKE ONTARIO WHERE SOME LAKE CONTRIBUTION COULD ALLOW FOR A BETTER CONCENTRATION FOR SNOW. MORE ON THIS WITH THE NEXT UPDATE. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... THE CLIPPER SYSTEM WILL PASS ACROSS FAR NORTHERN NEW YORK AND NORTHERN NEW ENGLAND SUNDAY INTO SUNDAY NIGHT. AS IS USUALLY THE CASE WITH THESE CLIPPER SYSTEMS...EXPECT MOST OF THE SIGNIFICANT SNOWFALL ASSOCIATED WITH IT TO REMAIN ALONG OR TO THE NORTH OF THE SURFACE LOW TRACK. THIS WILL RESULT IN VERY LITTLE PCPN FOR MOST OF THE ALBANY FORECAST AREA WITH THE EXCEPTION OF THE ADIRONDACK ZONES. FOR MUCH OF HAMILTON AND NORTHERN HERKIMER COUNTIES...LIKELY POPS ARE FORECAST SUNDAY INTO SUNDAY NIGHT...WITH CHANCE TO SLIGHT CHANCE POPS ELSEWHERE. SNOWFALL AMOUNTS MAY REACH 4 TO 5 INCHES WITH THIS EVENT ACROSS PARTS OF THE ADIRONDACKS...BUT IT WILL BE SPREAD OUT OVER 24 TO 36 HOURS SO HAVE NOT ISSUED ANY ADVISORIES AT THIS TIME...AND NEITHER HAVE ANY OF THE SURROUNDING OFFICES. AFTER THE LOW MOVES TO THE EAST...A LARGE HIGH PRESSURE SYSTEM WILL TAKER CONTROL OF OUR WEATHER FOR MONDAY AND MONDAY NIGHT. THIS WILL NOT BE A VERY COLD AIRMASS SO TEMPS WILL BE NEAR OR ABOVE NORMAL DURING THAT TIME. FOR TEMPS...HIGHS SUNDAY WILL BE IN THE 30S. LOWS SUNDAY NIGHT IN THE TEENS TO MID 20S. HIGHS MONDAY IN THE 20S TO MID 30S...AND LOWS MONDAY NIGHT IN THE UPPER SINGLE NUMBERS AND TEENS AS CLEAR SKIES AND LIGHT WINDS ALLOW FOR GOOD RADIATIONAL COOLING. && .LONG TERM /TUESDAY THROUGH SATURDAY/... HIGH PRESSURE WILL DOMINATE MUCH OF THE LONG TERM PERIOD BEFORE A POTENTIAL STORM SYSTEM APPROACHES LATE NEXT WEEK. HIGH PRESSURE WILL BE SITUATED OVER THE EASTERN THIRD OF THE CONUS AS A DEEP UPPER-LEVEL TROUGH DEVELOPS OVER THE WEST COAST TO START THE LONG TERM PERIOD. THIS AREA OF HIGH PRESSURE WILL BEGIN TO SLIDE OFF THE EASTERN SEABOARD TUESDAY...ALLOWING A MILD WEST-SOUTHWESTERLY RETURN FLOW TO DEVELOP ACROSS THE AREA. TEMPERATURES LOOK TO REBOUND NICELY FROM THE ARCTIC AIRMASS THAT PRODUCED THE COLD TEMPERATURES DURING THE PREVIOUS WEEK. EXPECT THE TUESDAY-THURSDAY MORNING TIMEFRAME TO BE DRY FOR MOST OF THE FORECAST AREA...HOWEVER MENTIONED SLIGHT CHANCE POPS FOR NORTHERN AREAS AS THE 12Z GFS/ECMWF DEPICT A WEAK SHORTWAVE DIPPING SOUTH OUT OF THE NORTHERN STREAM FLOW THAT COULD SPAWN A FEW SNOW SHOWERS IN THE SOUTHERN ADIRONDACKS. A STORM SYSTEM WILL EJECT OUT OF THE PLAINS AND MIDWEST DURING MIDWEEK...HOWEVER THERE ARE STILL SIGNIFICANT TIMING AND QPF DIFFERENCES AMONGST THE GUIDANCE...USED A BLENDED APPROACH TO ACCOUNT FOR THESE DIFFERENCES. REGARDLESS...HAVE CHANCE POPS FOR THE THURSDAY NIGHT-FRIDAY MORNING TIMEFRAME AS GUIDANCE IS HONING IN ON THIS TIMEFRAME BEING ASSOCIATED WITH THE FRONTAL PASSAGE. CURRENT THERMAL PROFILES MAINLY SUGGEST A RAIN EVENT...ALTHOUGH THERE COULD BE A MIX OF RAIN AND SNOW TOWARDS DAYBREAK FRIDAY MORNING. TEMPERATURES ARE EXPECTED TO BE ABOVE AVERAGE DURING THE LONG TERM PERIOD WITH HIGHS GENERALLY IN THE LOW TO MID 40S IN VALLEY REGIONS AND MID TO UPPER 30S IN THE HIGHER TERRAIN BEGINNING WEDNESDAY AND LASTING THROUGH THE REMAINDER OF THE LONG TERM PERIOD. LOWS WILL GENERALLY BE IN THE MID 20S IN THE HIGHER TERRAIN TO LOW 30S IN VALLEY LOCATIONS. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... WEAK WARM ADVECTION ASSOCIATED WITH AN APPROACHING FRONTAL SYSTEM/UPPER LEVEL SHORTWAVE WILL ALLOW MID LEVEL CLOUDS TO CONTINUE TO THICKEN AND LOWER FOR THE REMAINDER OF THE NIGHT. UPSTREAM RADARS SHOWS SOME LIGHT SNOW SHOWERS/FLURRIES...BUT MUCH OF THIS ACTIVITY LOOKS TO HAVE A DIFFICULT TIME MAKING ITS WAY TO THE SURFACE THANKS TO THE DRY AIR IN PLACE AT LOW LEVELS. HIRES MESOSCALE MODELS SUGGEST THESE SNOW SHOWERS MAY AFFECT OUR AREA BETWEEN 08Z-12Z...SO WILL INCLUDE A VCSH DURING THIS TIME PERIOD. HAVE ALSO INCLUDED A TEMPO FOR MVFR VSBYS IN CASE A BRIEF PERIOD OF LOWER VSBYS OCCUR WITHIN ANY SNOW SHOWER...BUT IFR CONDITIONS ARE NOT ANTICIPATED AT THIS TIME. CIGS SHOULD LOWER TO ABOUT 4-6 KFT TOWARDS THE END OF THE NIGHT WITH THE PASSING WARM FRONT. WINDS FOR THE REMAINDER OF THE LIGHT WITH BE SOUTHERLY AND VERY LIGHT /5 KTS OR LESS/ OR CALM. THE BEST WARM AIR ADVECTION WILL SHIFT EAST OF THE REGION FOR DURING THE DAY SUNDAY...PUTTING OUR AREA IN A LULL FOR PRECIPITATION. AS A RESULT...WILL NOT MENTION A VCSH DURING THE DAY SUNDAY WITH JUST SOME LINGERING BKN LOW AND MID LEVEL CLOUDS AND CONTINUED VFR CONDITIONS. SOUTHERLY AREAS...SUCH AS AROUND KPOU...MAY HAVE CLOUDS SCT OUT FOR THE AFTN HOURS. LIGHT SW WINDS OF 7 KTS OR LESS WILL BE IN PLACE THROUGHOUT THE AREA. THE STORM/S COLD FRONT LOOKS TO APPROACH THE AREA FOR SUNDAY EVENING/OVERNIGHT...SO WILL HAVE BKN-OVC CIGS OF 4-7 KFT AND INCLUDE A MENTION OF VCSH...ALTHOUGH THE BEST CHC FOR -SHSN WILL BE ACROSS THE HIGHER TERRAIN. FLYING CONDITIONS LOOK TO STAY VFR FOR THE MAJORITY OF THE TIME. WESTERLY WINDS WILL BE AROUND 5 KTS. OUTLOOK... MON-WED...VFR. NO SIG WX. THU...VFR/MVFR. CHC -RASN. && .HYDROLOGY... NO HYDRO PROBLEMS ARE EXPECTED THE NEXT 5 DAYS RELATED TO QPF...AS MAINLY DRY WEATHER OR SNOW PRODUCING SYSTEMS WILL IMPACT THE ALBANY HYDRO SERVICE AREA /HSA/. MOST OF THESE WILL BE RATHER LIGHT. SOME RIVER GAGES ARE EXHIBITING SIGNS OF ICE EFFECTS...AND RIVER LEVEL READINGS LOOK UNREPRESENTATIVE. ICE WILL CONTINUE TO FORM AND THICKEN ON ALL WATERWAYS IN THE ALY HSA THROUGH THE WEEKEND. WE WILL HAVE TO MONITOR FOR ANY FREEZE UP JAMS...ESPECIALLY ALONG THE NRN PERIPHERY OF THE HSA. 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...SND/GJM NEAR TERM...BGM/SND/GJM SHORT TERM...GJM LONG TERM...IRL AVIATION...FRUGIS HYDROLOGY...GJM
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
940 AM EST SUN JAN 6 2013 .DISCUSSION... CURRENT...FOG AND LOW CLOUDS WERE LIFTING ALONG THE COAST WHILE INLAND FOG AND/OR LOW CLOUDS WERE STILL A PROBLEM. EXPECT THAT THE FOG AND LOW CLOUDS OVER THE INTERIOR WILL HAVE LIFTED BETWEEN 10AM/15Z AND 11AM/16Z. THIS MATCHES WELL WITH THE 10AM EXPIRATION OF THE DENSE FOG ADVISORY. THE WEST PALM BEACH AIRPORT RADAR WAS DETECTING SHOWERS MOVING SOUTH TO NORTH ALONG THE IMMEDIATE MARTIN AND SAINT LUCIE COAST WEST TO INTERSTATE 95. LATEST RUC40 GUIDANCE RUN WAS SHOWING LITTLE MID LEVEL SUPPORT FOR ANYTHING MORE THAN ISOLATED SHOWERS THIS MORNING AND EARLY AFTERNOON. WENT WITH THAT SUGGESTION AND AMENDED THE WEATHER GRID OUT TO 2PM/19Z TO REFLECT ISOLATED SHOWERS TO MID AFTERNOON THEN START THE MORE SIGNIFICANT WEATHER MID TO LATE AFTERNOON. SAME RUC RUN ALSO INDICATING THAT THE BEST ISENTROPIC LIFT SHOULD START DURING THE AFTERNOON WITH THE STATIONARY BOUNDARY HAVING STARTED MOVING AGAIN AS A WARM FRONTAL BOUNDARY. && .AVIATION...VFR THROUGH LATE AFTERNOON. PREVAILING MVFR CEILINGS LATE AFTERNOON AND OVERNIGHT AS LIGHT RAIN IS EXPECTED TO START. && .MARINE... CURRENT...THE NOAA BUOYS WERE RECORDING LIGHT WINDS FROM THE NORTHEAST TO THE SOUTHEAST AND 3 FOOT SEAS. THE TWO SCRIPPS BUOYS WERE RECORDING 2 FOOT SEAS. THIS AFTERNOON...WINDS SHOULD REMAIN LIGHT WITH THE FRONTAL BOUNDARY IN THE AREA. ISOLATED SHOWERS SOUTH OF FORT PIERCE INLET THIS MORNING AND EARLY AFTERNOON. SHOWERS...SLIGHT CHANCE OF A LIGHTNING STORM THIS AFTERNOON AND EVENING. PREVIOUS MARINE DISCUSSION TODAY-TONIGHT...WEAK FRONTAL BOUNDARY LIFTING NORTH OVER WATERS THIS MORNING...CURRENTLY LOCATED AROUND CAPE CANAVERAL. WINDS WILL BE SOUTH-SOUTHEAST AT 10-15KTS SOUTH OF THE BOUNDARY AND E-NE 5KTS NORTH OF THE BOUNDARY. BOUNDARY IS EXPECTED TO STALL OVER THE VOLUSIA COUNTY WATERS THIS AFTERNOON...BEFORE GETTING PUSHED BACK TO THE SOUTH OVERNIGHT. WINDS WILL TURN N-NW BEHIND THE RETREATING FRONT...WITH A WIND SURGE INCREASING SPEEDS TO 15-20KTS TOWARDS DAYBREAK MONDAY. SEAS 2-3FT UNDER CHOPPY 5-6SEC PERIODS. PRESENCE OF THE BOUNDARY WILL LEAD TO SCT-NMRS SHOWERS THROUGH THE PERIOD WITH ISOLD TSTMS POSSIBLE THIS AFTERNOON AND OVERNIGHT...MAINLY OVER THE WARMER GULF STREAM WATERS. MON-THU...POST FRONTAL NE-E SURGE A LITTLE LESS ROBUST THAN EARLIER PROGGED...WITH WINDS/SEAS NOW FCST TO REMAIN A LITTLE BELOW SCA CUSP OF 20KT/7FT FOR THE NORTHERN HALF CWA THROUGH MONDAY EVENING...SO IT SEEMS CAUTIONARY STMT NORTH OF SEBASTIAN MAY BE MORE LIKELY SCENARIO FOR MON-MON EVENING. WINDS/SEAS GENERALLY STAY IN THE 12-18KT AND 3-5FT RANGE AS THE LOW LEVEL FLOW VEERS FROM E TO SE BY MID-LATE WEEK. && FPR 80 61 76 64 / 20 60 30 30 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ UPDATES/AVIATION...WIMMER IMPACT WX/RADAR....KELLY
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
621 AM CST SUN JAN 6 2013 .UPDATE... UPDATED FOR AVIATION DISCUSSION BELOW. && .PREV DISCUSSION.../ISSUED AT 347 AM CST SUN JAN 6 2013/ ONE THING THAT LOOKS CERTAIN IS THAT WE WILL GET A NICE JANUARY THAW COMING UP THIS WEEK. WHERE THERE ARE STILL QUESTIONS IS HOW WARM IS SAID THAW...AND IS IT ACCOMPANIED WITH RAIN IN THE THU/FRI TIMEFRAME. QUESTION MARKS DO NOT GO AWAY FOR THE WEEKEND IN TERMS OF THE WEATHER...WITH THE ONLY THING THAT LOOKS CERTAIN BY THE END OF THE WEEK INTO NEXT WEEKEND IS THAT THE MID SECTION OF THE COUNTRY LOOKS TO BE MORE ACTIVE. THE THAW IS COMING...JUST NOT TODAY. SFC LOW AT 3 AM WAS NEAR THE MACKINAC STRAIGHTS. SEEING WIDESPREAD STRATUS ACROSS NRN MN WITHIN CYCLONIC FLOW BEHIND THIS LOW. THIS STRATUS IS MAKING INROADS SOUTH AND SHOULD BLANKET MUCH OF NW QUARTER OF THE MPX CWA BY DAYBREAK. FOR NOW HAVE CLOUDS THINNING DURING THE MORNING...WITH MOSTLY SUNNY SKIES INDICATED BY THE AFTERNOON...BUT THE RAP /PER 925-850 MB RH/ KEEPS THE CLOUDS IN PLACE THROUGH THE DAY. CERTAINLY WOULD NOT BE THE FIRST TIME STRATUS GOT TRAPPED UNDER A DEVELOPING INVERSION...WHICH WE WILL SEE THANKS TO 12 HR H5 HEIGHT RISES IN EXCESS OF 120M BY THE AFTERNOON. EVEN WITHOUT THE CLOUD COVER...COOLER AIR THAT ARRIVED OVERNIGHT WILL HELP HOLD TEMPERATURES TODAY BACK INTO THE TEENS AND 20S. TONIGHT...WINDS WILL TURN OUT OF THE SW AND SHOULD BE QUITE STRONG RIGHT THROUGH THE EVENING OUT AHEAD OF COLD THAT WILL BE MOVING ACROSS NODAK. LLJ OUT AHEAD THE FRONT PROGGED BY THE GFS/NAM TO BE AROUND 60 KTS...SO THIS WILL QUICKLY BRING WARMER AIR BACK INTO THE REGION...WITH 925 MB TEMPS GETTING BACK UP AROUND THE 0C MARK BY MONDAY AFTERNOON. THE ONLY THING HOLDING THE AREA BACK FROM SEEING HIGHS IN THE MID AND EVEN UPPER 30S IS THE COLD FRONT QUICKLY MOVE THROUGH IN THE MORNING...BUT STILL SHOULD SEE HIGHS A FEW DEGS ON EITHER SIDE OF 30. FOR TUESDAY...A FAIRLY SHARP AND NEGATIVELY TILTED H5 TROUGH IS STILL FORECAST TO SWING THROUGH THE REGION. HAVE SEEN A SLIGHT SRN SHIFT WITH THE ECMWF TOWARD THE GFS WITH QPF WITH THIS WAVE...THOUGH IT STILL KEEPS QPF NORTH OF THE MPX CWA...WHERE IT TAKES THE PV ANOMALY. THE FIM/GFS AND EVEN THE 06.00 GEM ARE NOW BRINGING SOME PRECIP INTO THE NRN HALF OF THE MPX CWA. AT THIS POINT...KEPT POPS BELOW 15% THOUGH DID ADD A MENTION OF SCT FLURRIES ACROSS CENTRAL MN. MAIN REASON FOR NOT INCLUDING MENTIONABLE POPS IS THAT THE PRIMARY SFC LOW...EVEN ON THE SRN OUTLIER GFS IS PROGGED TO GO ACROSS SRN CANADA...WHICH WOULD HELP KEEP BETTER PRECIP CHANCES UP ALONG THE INTERNATIONAL BORDER. EVEN IF SNOW WERE TO OCCUR...IT WOULD BE ANOTHER HALF INCH OR LESS TYPE SNOWFALL. MODELS MAINTAIN DECENT AGREEMENT ON THE PROGRESSION OF THINGS NEXT WEEK THROUGH WEDNESDAY...BUT QUICKLY DIVERGE AFTER THAT...WITH EVEN RUN-TO-RUN CONSISTENCY WITHIN INDIVIDUAL MODELS BEING LESS THAN IDEAL. AT ISSUE IS HOW THEY HANDEL THE CLOSED H5 LOW THAT IS CURRENTLY NEAR SAN FRANCISCO. BY WEDNESDAY...THIS LOW WILL BE NEAR THE BIG BEND REGION OF TX AS A DEEP AND POSITIVELY TILTED TROUGH WORKS DOWN THE WEST COAST. AS ALL OF THIS IS GOING ON...AN IMPRESSIVE RIDGE WILL BE BUILDING ACROSS THE ERN CONUS...WITH 590 DM HEIGHTS EXPECTED OVER FLA AND THE 576 DM LINE CLEAR UP TO THE WI/IL BORDER. WHERE MODELS DIVERGE IS THE EXTENT WHICH THE CLOSED LOW WILL INTERACT WITH THE WEST COAST TROUGH. OVER THE PAST 24 HRS THE GFS AND ECMWF HAVE TRADED POSITIONS ON HOW TO HANDEL THE WAVE...WITH THE GFS NOW BRINGING THE WAVE NORTH TOWARD THE GREAT LAKES BY FRIDAY...WITH THE ECMWF TAKING THE WAVE ACROSS THE OHIO VALLEY. THE GEM/FIM ARE MORE IN LINE WITH THE GFS...THOUGH A LITTLE SLOWER. AT THIS POINT...GIVEN THE STRENGTH OF THE RIDGE EXPECTED OVER THE SE...FIND IT HARD TO BELIEVE THE ECMWF SOLUTION THAT IT WILL PLOW RIGHT THROUGH THE RIDGE AND WOULD FAVOR THE MORE WRN SOLUTIONS. WHERE THERE IS AGREEMENT HOWEVER WITH THE MODELS...IS THAT WHEREVER THE PRECIPITATION GOES...THICKNESSES WILL BE WARM ENOUGH ACROSS THE MPX CWA FOR ALL RAIN ON THURSDAY. IN FACT...MODELS DELAY THE ONSET OF THE COLD AIR BY A DAY NOW...WITH THE ECMWF AND GEM SHOWING HIGHS IN THE 40S ON FRIDAY ACROSS THE ERN HALF OF THE CWA...WHICH MEANS ANY TRANSITION BACK TO SNOW POSSIBLY WAITING UNTIL AS LATE AS FRIDAY NIGHT OR SATURDAY. BESIDE THE POTENTIAL FOR RAIN...TEMPERATURE AND DEWPOINT FORECASTS THURSDAY AND FRIDAY SHOW THE POTENTIAL FOR SOME AGGRESSIVE SNOW MELT FOR JANUARY STANDARDS. BESIDE HIGHS POSSIBLY PUSHING 40 ONE OR BOTH OF THE DAYS...THURSDAY NIGHT MAY SEE LOWS STAY ABOVE FREEZING...WITH DEWPOINTS EVEN GETTING INTO THE MID/UPPER 30S. EVEN WITHOUT ANY RAIN...THESE CONDITIONS WILL LIKELY LEAVE BARE SPOTS IN THE SNOW COVER BY THIS WEEKEND. AS FOR THE WEEKEND...MODEL AGREEMENT GETS NO BETTER. ABOUT ALL ONE CAN SAY IS THAT THE WRN TROUGH WILL CONTINUE TO PUSH EAST...AND AS IT DOES SO...MORE SEASONABLE AIR WILL MAKE A RETURN...WITH SOME SNOW STILL LOOKING POSSIBLE. && .AVIATION.../12Z TAF ISSUANCE/ TWO AREAS OF CIGS TO BE CONCERNED ABOUT THIS MORNING. ONE IS OVER WRN WI AND IS PRIMARILY MVFR. THE OTHER IS A NARROW FINGER OF IFR CIGS ACROSS WRN MN. RAP13 SEEMS TO HAVE A GOOD HANDLE ON THESE AREAS...SO FOLLOWED THIS SOLUTION WITH A FEW TWEAKS TOWARD THE LAMP GUIDE. THE CIGS OVER WRN MN SHOULD SLIDE EAST SLOWLY THIS MORNING AND BEGIN DISSIPATING. THE BACK EDGE IS ABOUT OVER RWF AND SHOULD CLEAR AXN AROUND 14-15Z. IT WILL HOWEVER BEGIN TO AFFECT STC AROUND 13Z...AND REMAIN NEARLY STATIONARY UNDER THE RIDGE AXIS THROUGH THE MORNING BEFORE DISSIPATING SOMETIME AROUND 18Z. FURTHER EAST...RNH AND MSP SHOULD BE VFR THROUGH THE PERIOD BEING SANDWICHED BETWEEN THE TWO AREAS OF STRATUS. FINALLY...EAU WILL SEE IMPROVING CONDITIONS AS THE MVFR STRATUS ROTATES OUT TO THE EAST THIS MORNING. WINDS ARE EXPECTED TO TURN SOUTHERLY AND STRENGTHEN THIS EVENING. FORECAST SOUNDINGS STILL INDICATE THE POTENTIAL FOR 50+ KT WINDS ABOVE 1000FT. A PRETTY DEEP INVERSION SHOULD DAMPEN WIND GUST POTENTIAL TO LESS THAN 25 KTS AT THE SURFACE AND HAS ALLOWED THE EXCLUSION OF WIND SHEAR MENTION ATTM. KMSP...VFR CONDITIONS EXPECTED AS TWO AREAS OF STRATUS LIKELY REMAIN REMOVED FROM THE VICINITY OF THE TERMINAL. NORTHWEST WINDS WILL BACK SOUTHWEST THIS AFTERNOON AND TO SOUTH TONIGHT. SPEEDS WILL REMAIN LIGHT THROUGH TODAY...THEN INCREASE WITH LLJ PUSHING OVERHEAD TONIGHT. /OUTLOOK FOR KMSP/ MON...VFR. WINDS SW 10 KTS. TUE...VFR. WINDS SE 4-8 KTS. WED...VFR. WINDS S 10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ MPG/BORGHOFF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
347 AM CST SUN JAN 6 2013 .DISCUSSION... ONE THING THAT LOOKS CERTAIN IS THAT WE WILL GET A NICE JANUARY THAW COMING UP THIS WEEK. WHERE THERE ARE STILL QUESTIONS IS HOW WARM IS SAID THAW...AND IS IT ACCOMPANIED WITH RAIN IN THE THU/FRI TIMEFRAME. QUESTION MARKS DO NOT GO AWAY FOR THE WEEKEND IN TERMS OF THE WEATHER...WITH THE ONLY THING THAT LOOKS CERTAIN BY THE END OF THE WEEK INTO NEXT WEEKEND IS THAT THE MID SECTION OF THE COUNTRY LOOKS TO BE MORE ACTIVE. THE THAW IS COMING...JUST NOT TODAY. SFC LOW AT 3 AM WAS NEAR THE MACKINAC STRAIGHTS. SEEING WIDESPREAD STRATUS ACROSS NRN MN WITHIN CYCLONIC FLOW BEHIND THIS LOW. THIS STRATUS IS MAKING INROADS SOUTH AND SHOULD BLANKET MUCH OF NW QUARTER OF THE MPX CWA BY DAYBREAK. FOR NOW HAVE CLOUDS THINNING DURING THE MORNING...WITH MOSTLY SUNNY SKIES INDICATED BY THE AFTERNOON...BUT THE RAP /PER 925-850 MB RH/ KEEPS THE CLOUDS IN PLACE THROUGH THE DAY. CERTAINLY WOULD NOT BE THE FIRST TIME STRATUS GOT TRAPPED UNDER A DEVELOPING INVERSION...WHICH WE WILL SEE THANKS TO 12 HR H5 HEIGHT RISES IN EXCESS OF 120M BY THE AFTERNOON. EVEN WITHOUT THE CLOUD COVER...COOLER AIR THAT ARRIVED OVERNIGHT WILL HELP HOLD TEMPERATURES TODAY BACK INTO THE TEENS AND 20S. TONIGHT...WINDS WILL TURN OUT OF THE SW AND SHOULD BE QUITE STRONG RIGHT THROUGH THE EVENING OUT AHEAD OF COLD THAT WILL BE MOVING ACROSS NODAK. LLJ OUT AHEAD THE FRONT PROGGED BY THE GFS/NAM TO BE AROUND 60 KTS...SO THIS WILL QUICKLY BRING WARMER AIR BACK INTO THE REGION...WITH 925 MB TEMPS GETTING BACK UP AROUND THE 0C MARK BY MONDAY AFTERNOON. THE ONLY THING HOLDING THE AREA BACK FROM SEEING HIGHS IN THE MID AND EVEN UPPER 30S IS THE COLD FRONT QUICKLY MOVE THROUGH IN THE MORNING...BUT STILL SHOULD SEE HIGHS A FEW DEGS ON EITHER SIDE OF 30. FOR TUESDAY...A FAIRLY SHARP AND NEGATIVELY TILTED H5 TROUGH IS STILL FORECAST TO SWING THROUGH THE REGION. HAVE SEEN A SLIGHT SRN SHIFT WITH THE ECMWF TOWARD THE GFS WITH QPF WITH THIS WAVE...THOUGH IT STILL KEEPS QPF NORTH OF THE MPX CWA...WHERE IT TAKES THE PV ANOMALY. THE FIM/GFS AND EVEN THE 06.00 GEM ARE NOW BRINGING SOME PRECIP INTO THE NRN HALF OF THE MPX CWA. AT THIS POINT...KEPT POPS BELOW 15% THOUGH DID ADD A MENTION OF SCT FLURRIES ACROSS CENTRAL MN. MAIN REASON FOR NOT INCLUDING MENTIONABLE POPS IS THAT THE PRIMARY SFC LOW...EVEN ON THE SRN OUTLIER GFS IS PROGGED TO GO ACROSS SRN CANADA...WHICH WOULD HELP KEEP BETTER PRECIP CHANCES UP ALONG THE INTERNATIONAL BORDER. EVEN IF SNOW WERE TO OCCUR...IT WOULD BE ANOTHER HALF INCH OR LESS TYPE SNOWFALL. MODELS MAINTAIN DECENT AGREEMENT ON THE PROGRESSION OF THINGS NEXT WEEK THROUGH WEDNESDAY...BUT QUICKLY DIVERGE AFTER THAT...WITH EVEN RUN-TO-RUN CONSISTENCY WITHIN INDIVIDUAL MODELS BEING LESS THAN IDEAL. AT ISSUE IS HOW THEY HANDEL THE CLOSED H5 LOW THAT IS CURRENTLY NEAR SAN FRANCISCO. BY WEDNESDAY...THIS LOW WILL BE NEAR THE BIG BEND REGION OF TX AS A DEEP AND POSITIVELY TILTED TROUGH WORKS DOWN THE WEST COAST. AS ALL OF THIS IS GOING ON...AN IMPRESSIVE RIDGE WILL BE BUILDING ACROSS THE ERN CONUS...WITH 590 DM HEIGHTS EXPECTED OVER FLA AND THE 576 DM LINE CLEAR UP TO THE WI/IL BORDER. WHERE MODELS DIVERGE IS THE EXTENT WHICH THE CLOSED LOW WILL INTERACT WITH THE WEST COAST TROUGH. OVER THE PAST 24 HRS THE GFS AND ECMWF HAVE TRADED POSITIONS ON HOW TO HANDEL THE WAVE...WITH THE GFS NOW BRINGING THE WAVE NORTH TOWARD THE GREAT LAKES BY FRIDAY...WITH THE ECMWF TAKING THE WAVE ACROSS THE OHIO VALLEY. THE GEM/FIM ARE MORE IN LINE WITH THE GFS...THOUGH A LITTLE SLOWER. AT THIS POINT...GIVEN THE STRENGTH OF THE RIDGE EXPECTED OVER THE SE...FIND IT HARD TO BELIEVE THE ECMWF SOLUTION THAT IT WILL PLOW RIGHT THROUGH THE RIDGE AND WOULD FAVOR THE MORE WRN SOLUTIONS. WHERE THERE IS AGREEMENT HOWEVER WITH THE MODELS...IS THAT WHEREVER THE PRECIPITATION GOES...THICKNESSES WILL BE WARM ENOUGH ACROSS THE MPX CWA FOR ALL RAIN ON THURSDAY. IN FACT...MODELS DELAY THE ONSET OF THE COLD AIR BY A DAY NOW...WITH THE ECMWF AND GEM SHOWING HIGHS IN THE 40S ON FRIDAY ACROSS THE ERN HALF OF THE CWA...WHICH MEANS ANY TRANSITION BACK TO SNOW POSSIBLY WAITING UNTIL AS LATE AS FRIDAY NIGHT OR SATURDAY. BESIDE THE POTENTIAL FOR RAIN...TEMPERATURE AND DEWPOINT FORECASTS THURSDAY AND FRIDAY SHOW THE POTENTIAL FOR SOME AGGRESSIVE SNOW MELT FOR JANUARY STANDARDS. BESIDE HIGHS POSSIBLY PUSHING 40 ONE OR BOTH OF THE DAYS...THURSDAY NIGHT MAY SEE LOWS STAY ABOVE FREEZING...WITH DEWPOINTS EVEN GETTING INTO THE MID/UPPER 30S. EVEN WITHOUT ANY RAIN...THESE CONDITIONS WILL LIKELY LEAVE BARE SPOTS IN THE SNOW COVER BY THIS WEEKEND. AS FOR THE WEEKEND...MODEL AGREEMENT GETS NO BETTER. ABOUT ALL ONE CAN SAY IS THAT THE WRN TROUGH WILL CONTINUE TO PUSH EAST...AND AS IT DOES SO...MORE SEASONABLE AIR WILL MAKE A RETURN...WITH SOME SNOW STILL LOOKING POSSIBLE. && .AVIATION... /06Z TAF ISSUANCE/ PATCHY MVFR CEILINGS FROM KSTC THROUGH THE TWIN CITIES AND EASTWARD INTO WEST CENTRAL WI WILL CONTINUE TO MEANDER SE EARLY IN THE TAF PERIOD IN THE WAKE OF A COLD FRONT. A SMALL BREAK EXISTS TO THE WEST BEFORE MORE WIDESPREAD MVFR CEILINGS ARE PUSHING IN FROM THE DAKOTAS NEAR 20 KNOTS. SHORT TERM GUIDANCE SUGGESTS THIS CLOUDINESS WILL REACH INTO KAXN BY 08Z AND INTO KRWF AND KSTC AROUND 10Z. THIS WILL LIKELY PERSIST THROUGH DAYBREAK BEFORE DIMINISHING DURING THE MORNING AS THE LOW LEVEL FLOW BECOMES MORE ANTICYCLONIC. VFR CONDITIONS FOR THE AFTERNOON AND EVENING AS A RIDGE OF HIGH PRESSURE MOVES BY. THE PRESSURE GRADIENT WILL TIGHTEN SUNDAY NIGHT WITH SOUTH WINDS INCREASING TO NEAR 15 KNOTS FOR KRWF AND KAXN. THIS GRADIENT WILL SPREAD INTO THE EASTERN TAF SITES DURING THE NIGHT. WINDS MONDAY MORNING AT 1500 FEET ARE PROJECTED TO BE NEAR 50 KNOTS. KMSP...PATCHY MVFR CEILINGS WILL OCCUR EARLY THIS MORNING. CEILINGS NEAR 015 SHOULD BEGIN MOVING IN BETWEEN 07Z-09Z. CONFIDENCE INCREASING THAT THESE LOWER MVFR CEILINGS WILL PERSIST INTO THE MID MORNING HOURS. VFR FOR THE AFTERNOON AND NIGHT. NORTHWEST WINDS 6-9 KNOTS OVERNIGHT AND SUNDAY MORNING BACKING TO THE WEST IN THE AFTERNOON AND THEN TO SOUTH 12 KNOTS SUNDAY NIGHT. /OUTLOOK FOR KMSP/ MON...VFR. WINDS SW 12-15 KTS GUSTING 20 KTS. TUE...VFR. WINDS S 4-8 KTS. WED...VFR. WINDS WSW 5 TO 10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ MPG/RAH
AREA FORECAST DISCUSSION
NWS DULUTH MN
1136 PM CST SAT JAN 5 2013 .AVIATION.../06Z TAF ISSUANCE/ SKY COVER WILL CONTINUE TO DECREASE THIS MORNING FROM THE WEST...WITH A MVFR DECK SCTRG OUT AT KDLH BY 12Z AND KHYR BY 15Z. WEAK RIDGING ACROSS THE NORTHLAND WILL THEN RESULT IN VFR CONDITIONS FOR THE REST OF THE TAF PERIOD. WINDS WILL BECOME MAINLY LIGHT AND VARIABLE LATER THIS MORNING...THEN TURN OUT OF THE SOUTHWEST AND STRENGTHEN BY LATE SUNDAY AFTERNOON...ESPECIALLY ACROSS OUR WRN ZONES TO DULUTH. && .PREV DISCUSSION... /ISSUED 723 PM CST SAT JAN 5 2013/ UPDATE... LOW PRESSURE IN UPPER MICHIGAN CONTINUE TO MOVE EAST THIS EVENING...WITH WINDS BECOMING NORTH OVER LAKE SUPERIOR...AND LOWER CLOUDS MOVING OVER NORTHERN WISCONSIN AS WELL. MORE CLOUDS OVER THE RED RIVER VALLEY WERE MOVING E-SE THIS EVENING...AND THE RAP 900-925MB CONDENSATION PRESSURE DEFICITS WERE HANDLING THIS PRETTY WELL...AND IT BRINGS THESE CLOUDS TO OUR WESTERN BORDER LATE TONIGHT. WE`LL HAVE TO KEEP AN EYE ON THESE AND INCREASE CLOUD COVER IF THEY HAPPEN TO MOVE IN FASTER. WE DON`T PLAN ON ANY MAJOR CHANGES TO THE GRIDS OVERNIGHT...WE STILL EXPECT LAKE EFFECT SNOW SHOWERS TO DEVELOP IN THE SNOWBELT...MAINLY IN IRON/ASHLAND COUNTIES. WE DID INCREASE SNOWFALL A BIT OVER IRON COUNTY AS INVERSION LEVELS INCREASE TONIGHT WITH DELTA-T`S FORECAST TO ABOUT 15-17C. PREV DISCUSSION... /ISSUED 535 PM CST SAT JAN 5 2013/ AVIATION...00Z TAFS IFR/LOW MVFR CEILINGS COVERED MUCH OF NORTHEAST MINNESOTA...AND THEY WERE WORKING THEIR WAY SOUTH INTO NORTHWEST WISCONSIN AS WELL. MORE LOW CEILINGS WERE OVER PORTIONS OF EASTERN NORTH DAKOTA. WE EXPECT THOSE CEILINGS WILL WORK EAST THROUGH THE NIGHT...BUT THE RAP WHICH IS HANDLING THEM PRETTY WELL...KEEPS THEM WEST OF KINL/KBRD THROUGH 14Z. A SURFACE LOW OVER WESTERN UPPER MICHIGAN WILL CONTINUE TO MOVE OFF TONIGHT...DRAWING THOSE LOWER CEILINGS SOUTH AND EAST. WE KEPT THE MENTION OF THESE CLOUDS IN THE KDLH/KHIB TAFS THROUGH ABOUT 7-8Z...AND UNTIL 15Z AT KHYR. MOST AREAS WILL BE VFR ON SUNDAY...OUTSIDE OF SOME LAKE CLOUDS ALONG THE SOUTH SHORE. PREV DISCUSSION... /ISSUED 251 PM CST SAT JAN 5 2013/ SHORT TERM... THIS AFTERNOON/TONIGHT THROUGH SUNDAY NIGHT... MAIN CONCERNS IN THE SHORT TERM ARE FOCUSED AROUND THE CHANCE OF LIGHT SNOW EXPECTED TO DEVELOP THIS EVENING ACROSS NE MN AND LINGER THROUGH NW WI INTO SUNDAY MORNING...ALONG WITH TEMPERATURES THROUGH THE NEAR TERM. ATMOSPHERE REMAINS FAIRLY DRY ACROSS THE REGION WITH A SHARP UPPER TROUGH OVER THE RED RIVER VALLEY MOVING EWD INTO NRN MN THIS AFTERNOON. BENIGN SFC LOW CURRENTLY POSITIONED NEAR LAKE MILLE LACS WITH LITTLE IN THE WAY OF CLOUD COVER ASSOCIATED WITH IT ATTM. LOW LEVEL FLOW PATTERN WITH EAST WINDS OFF LAKE SUPERIOR INTO THE ARROWHEAD HAVE ALLOWED LOW CLOUDS TO PERSIST OVER THE NRN THIRD OF THE FORECAST AREA TODAY. THIS AREA OF LOW CLOUDS WILL COMBINE WITH THE INCOMING S/W AND INCREASE IN AREAL COVERAGE BEFORE DEVELOPING LIGHT SNOW/FLURRIES ALONG AND EAST OF HIGHWAY 53 EARLY THIS EVENING. ONLY LIGHT OR TRACE ACCUMULATIONS ARE EXPECTED OVER NE MN TONIGHT. BY LATE THIS EVENING...THE BL FLOW ACROSS WRN LAKE SUPERIOR WILL BECOME MORE NRLY AS THE SFC LOW SLIDES FURTHER TO THE EAST. THE COMBINATION OF 15 TO 25 KT NORTH WINDS OFF THE LAKE WITH A LONG FETCH OVER WATER...A RELATIVELY DEEP BL ROUGHLY 3-4K FT...AND COLD ENOUGH TEMPS ALOFT TO PRODUCE MODEST LOW LVL INSTABILITY...THE POTENTIAL FOR LIGHT LAKE EFFECT SNOW ALONG THE SOUTH SHORE ARISES. LAKE TEMPS ARE AROUND +2.7 DEG C AND 850MB TEMPS WILL BE -11 TO -12 DEG C. KEPT WITH PREVIOUS FORECAST OF LIKELY POPS FROM NRN BAYFIELD TO NRN ASHLAND/IRON COUNTIES FROM 06-12Z LATE TONIGHT/EARLY SUN MORNING...AND GENERALLY 1-2 INCHES OF SNOW IN THIS AREA. HIGH PRESSURE QUICKLY BUILDS IN SUNDAY AFTERNOON AND ALLOWS CONDITIONS TO DRY OUT. SHOULD SEE MOSTLY SUNNY TO PARTLY CLOUDY SKIES FOR THE END OF THE WEEKEND. LOW TEMPERATURES TONIGHT WILL BE SOMEWHAT TRICKY AS CLOUD COVER COULD END UP BEING PATCHY IN NATURE OVER PARTS OF NE MN. WILL LIKELY SEE SINGLE DIGITS ABOVE AND BELOW ZERO ACROSS NRN MN...WITH A FEW TEENS BELOW ZERO NOT OUT OF THE QUESTION WHERE ADDITIONAL CLEARING OCCURS. AREAS TO THE EAST IN NW WI WILL BE SLIGHTLY WARMER WITH ADDITIONAL CLOUD COVER ALMOST CERTAIN. SHOULD SEE LOWER TO MID TEENS IN THIS AREA. ON SUNDAY...A LINGERING COLD AIR MASS WILL ONLY ALLOW TEMPS TO REACH INTO THE UPPER TEENS TO MID 20S...EVEN WITH MOSTLY SUNNY SKIES IN THE AFTERNOON. LOWS SUNDAY NIGHT WILL DROP INTO THE UPPER SINGLE DIGITS AND TEENS ABOVE ZERO...WITH HIGH CLOUDS MOVING IN FROM THE NW. LONG TERM... MONDAY THROUGH SATURDAY... AN UNSEASONABLY MILD PATTERN WILL CONTINUE THROUGHOUT THE EXTENDED TIME PERIOD ACROSS THE NORTHLAND. IT ALSO LOOKS FAIRLY QUIET FOR THE MOST PART. LOW PRESSURE MOVING ACROSS THE CENTRAL CANADIAN PROVINCES WILL AFFECT AREAS MAINLY NORTH OF THE BORDER ON MONDAY AND MONDAY NIGHT...WITH A FAIR AMOUNT OF SUNSHINE FURTHER SOUTH. THE MODELS DIVERGE QUITE A BIT IN HOW THEY HANDLE A SYSTEM ON TUESDAY AND WEDNESDAY. THE ECMWF AND GEM ARE FAIRLY SIMILAR BUT THE GFS SHOWS A LOW PRESSURE SYSTEM DEVELOPING IN CENTRAL NORTH DAKOTA BY 00Z WEDNESDAY. THE RESULT COULD BE SOME SCATTERED SNOW SHOWERS TUESDAY NIGHT AND WEDNESDAY AS THE SYSTEM MOVES THROUGH. HIGH PRESSURE WILL GENERALLY CONTROL LATER WEDNESDAY AND WEDNESDAY NIGHT. THURSDAY LOOKS QUITE MILD WITH TEMPS WELL INTO THE 30S AHEAD OF LOW PRESSURE DEVELOPING IN THE NORTHERN ROCKIES. THERE ARE SOME HUGE MODEL DIFFERENCES BEGINNING ON FRIDAY AND CONTINUING INTO THE WEEKEND SO KEEPING POPS LOW FOR NOW. THE GFS CONTINUES TO TRY TO DEVELOP A MAJOR LOW BY NEXT WEEKEND...WHICH WOULD IMPACT OUR AREA. THE ECMWF IS MUCH FURTHER SE AND NOT NECESSARILY OF MUCH CONCERN FOR OUR CWA. DEFINITELY SOMETHING TO KEEP AN EYE ON...AS THE GFS HAS BEEN REASONABLY CONSISTENT. && .POINT TEMPS/POPS... DLH 8 20 10 30 / 20 0 0 10 INL -1 17 12 28 / 10 0 0 10 BRD 4 21 12 31 / 10 0 0 10 HYR 12 22 9 33 / 30 10 0 10 ASX 15 24 13 34 / 50 20 0 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 10 AM CST SUNDAY FOR LSZ121-146>148. && $$ AVIATION...BERDES
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
522 PM CST MON JAN 7 2013 .AVIATION... 00Z TAFS FOR KOMA...KLNK...KOFK. WILL HAVE TO MONITOR FOR DEVELOPMENT OF STRATUS AND FOG TONIGHT. DID MENTION SOME MVFR VISIBILITIES LATER TONIGHT BUT DID NOT WANT TO GET TOO PESSIMISTIC. GFS MODEL DOES NOT DEVELOP FOG...WHILE THE NAM DOES. GENERALLY FELT THE NAM LOW LEVEL MOISTURE WAS OVERDONE BUT WILL MONITOR AND AMEND TAFS THROUGH THE EVENING AS NEEDED. MILLER && .PREV DISCUSSION... /ISSUED 234 PM CST MON JAN 7 2013/ SHORT TERM...TONIGHT THROUGH THURSDAY. MAIN FORECAST CONCERNS WILL DEAL WITH TEMPERATURES AND TIMING OF SYSTEM MOVING OUT OF THE SOUTHERN PLAINS WEDNESDAY NIGHT INTO THURSDAY. DESPITE THICK CIRRUS LAYER ACROSS PARTS OF THE AREA AND LIGHT SURFACE WINDS ALONG A WEAK TROUGH INTO EAST CENTRAL NEBRASKA... TEMPERATURES HAVE MANAGED TO CLIMB INTO THE MID AND UPPER 30S IN SNOW COVERED PORTION OF THE CWA WITH MID 40S TO LOWER 50S IN SNOW FREE PARTS OF SOUTHEAST NEBRASKA AND SOUTHWEST IOWA THIS AFTERNOON. INITIAL CONCERN FOR TONIGHT WILL BE POTENTIAL FOG DEVELOPMENT IN THE SNOW AREAS WHERE SOME MELTING TODAY HAS ADDED MOISTURE TO THE BOUNDARY LAYER. SHORT RANGE RAP HINTS AT DEVELOPMENT AFTER 06Z IN AREA WHERE MENTION OF PATCHY FOG IS ALREADY IN CURRENT FORECAST. FOR TUESDAY AND WEDNESDAY QUESTION WILL BE HOW WARM WILL TEMPERATURES BE ABLE TO REACH. BASED ON TODAYS READINGS CLIMBING TO AROUND 50 IN THE SOUTHEAST PART OF THE CWA...HAVE WENT A WARMER THAN GUIDANCE IN THE SNOW FREE AREAS WITH SNOW FIELD STILL EXPECTED TO KEEP TEMPERATURES TO THE NORTH CLOSE TO GUIDANCE. TIMING ISSUES AMONG THE MODELS STILL IN PLAY FOR WEDNESDAY NIGHT AND THURSDAY WITH NAM THE FASTEST AND LEAST REGARDED AT THIS TIME FRAME. GFS AND EURO HAVE BETTER AGREEMENT BUT EURO REMAINS SLOWER IN MOVING THE SYSTEM ACROSS THE AREA. FORECAST SOUNDINGS FOR WEDNESDAY NIGHT SUGGEST TEMPERATURES SHOULD BE WARM ENOUGH ACROSS THE SOUTH HALF OF THE AREA FOR PRECIP TO BE ALL LIQUID WITH TEMPERATURES REMAINING ABOVE FREEZING ON THURSDAY ACROSS ALL THE AREA AS RAIN CONTINUES. FOBERT LONG TERM...THURSDAY NIGHT THROUGH MONDAY. THE GFS AND ECM ARE IN RELATIVELY GOOD AGREEMENT WITH REGARDS TO LARGE SCALE IN THE EXTENDED PD. BOTH ALSO SUGGESTING LITTLE CHANGE NEEDED TO GOING FCST. HEADING INTO NEXT WEEKEND...MODELS ADVERTISE SHORTWAVE ENERGY OVER IA QUICKLY LIFTING TO THE GREAT LAKES REGION LATE THURSDAY NIGHT. MEANWHILE UPSTREAM...A DEEP LONGWAVE TROF IS PROGGED TO EXTEND FROM CNTRL CANADA ALL THE WAY TO THE SWRN CONUS. ON FRIDAY AS THE WRN TROF GRADUALLY MIGRATES EAST...INTENSE BAROCLINIC ZONE BEGINS SWEEPING ACROSS THE NRN/CNTRL PLAINS WITH THE LEADING EDGE OF THE BOUNDARY REACHING THE CWA BY EARLY AFTN. COMBINATION OF INCREASING MOISTURE AND STOUT AGEOSTROPHIC LIFT ALONG DEEP FRONTOGENETIC LYR SHOULD BE ENOUGH TO INDUCE LIGHT SNOW ACTIVITY DURING THE FROPA FRIDAY NIGHT. ON SATURDAY...APPEARS TO BE A SMALL CHANCE FOR LIGHT POST-FRONTAL SNOW ACTIVITY PER THE ECM. 300-500MB QVEC CONVERGENCE IMPLYING LIFT VIA DPVA WHEN POTENT OR MAX ROUNDS THE BASE OF THE WRN TROF AND LIFTS ACROSS THE CNTRL PLAINS. ON THE OTHER HAND...GFS AND CMC BOTH SUGGESTING THE DEEP CAA WILL BE ADEQUATE TO SUPPRESS ANY LIFT VIA DPVA. WILL OPTED FOR TOKEN 20S JUST IN CASE ECM SOLUTION WOULD VERIFY. OTHERWISE...TEMPS WILL PLUMMET OVER THE PLAINS NEXT WEEKEND INTO EARLY NEXT WEEK. EXPECT HIGHS SAT-MON WILL STRUGGLE TO REACH THE LOWER/MID 20S. DEE && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1001 AM EST SUN JAN 6 2013 .SYNOPSIS... A WEAK AREA OF LOW PRESSURE WILL BRING MINOR SNOW ACCUMULATIONS TO MOST LOCATIONS THIS AFTERNOON AND EVENING...BUT SNOWS WILL BE A BIT STEADIER EAST OF LAKE ONTARIO. HIGH PRESSURE WILL THEN BUILD INTO THE OHIO VALLEY AND EASTERN GREAT LAKES FOR THE FIRST HALF OF NEXT WEEK WITH DRY WEATHER AND WARMING TEMPERATURES. THE JANUARY THAW WILL LAST RIGHT THROUGH NEXT WEEKEND WITH MILD TEMPERATURES AND INCREASING CHANCES OF RAIN. && .NEAR TERM /THROUGH TONIGHT/... A WIDESPREAD AREA OF MAINLY LIGHT WET SNOW HAS BLOSSOMED ACROSS ALL OF WESTERN NY THIS MORNING...MIXED WITH RAIN ALONG THE LAKESHORES AND NIAGARA COUNTY. THIS APPEARS TO BE TIED TO WEAK ASCENT JUST AHEAD OF A WEAK SHORTWAVE APPARENT IN WATER VAPOR IMAGERY CROSSING CENTRAL LAKE ERIE THIS MORNING. MODEL GUIDANCE IS NOT CAPTURING THIS AT ALL...SO HAVE UPDATED THE GRIDS BASED SOLELY ON EXTRAPOLATION OF CURRENT RADAR TRENDS FOR THE NEXT 6 HOURS OR SO. EXPECT STEADY LIGHT SNOW ACROSS WESTERN NY THROUGH AT LEAST EARLY AFTERNOON. AT LOWER ELEVATIONS TEMPERATURES ARE ALREADY ABOVE FREEZING...SO JUST EXPECT LESS THAN AN INCH OF ACCUMULATION ON EXISTING SNOW...WITH ROADS JUST REMAINING WET. SOME RAIN WILL ALSO MIX IN AT LOWER ELEVATIONS. THE HIGHER TERRAIN OF THE SOUTHERN TIER MAY PICK UP AN INCH OR SO TODAY AS TEMPERATURES REMAIN CLOSER TO THE FREEZING MARK. IT APPEARS THIS AREA OF WET SNOW WILL STRUGGLE TO MOVE EAST...WITH JUST A FEW BRIEF SNOW OR RAIN SHOWERS FROM THE GENESEE VALLEY INTO CENTRAL NY THIS AFTERNOON. EAST OF LAKE ONTARIO EXPECT A SIMILAR BLOSSOMING OF LIGHT SNOW BY EARLY AFTERNOON AS THE SHORTWAVE MOVES EAST AND INTERACTS WITH AN OLD FRONTAL BOUNDARY STILL IN THE VICINITY. EXPECT AROUND AN INCH THERE THIS AFTERNOON...WITH UP TO 2 INCHES ACROSS THE TUG HILL AND WESTERN FOOTHILLS OF THE ADIRONDACKS. THE NEXT PART OF THIS GENERALLY WEAK SYSTEM WILL IMPACT THE REGION DURING THE LATE AFTERNOON AND EVENING HOURS. THE KEY WILL BE THE PASSAGE OF ANOTHER SHORT WAVE...WHICH WILL HELP DRIVE A COLD FRONT ACROSS THE REGION. HOWEVER...THERE WILL BE WELL ALIGNED SOUTHWEST FLOW AHEAD OF THIS...WITH AMPLE MOISTURE AND A LONG FETCH. 850 MB TEMPERATURES WILL ONLY BE AROUND -7C...WITH LAKE INDUCED CAPES BARELY MEASURABLE. HOWEVER...THIS WILL PROBABLY BE ENOUGH TO BOOST MOISTURE A BIT...AND BRING A PERIOD OF SNOW TO MOST LOCATIONS. THE QPF FORECAST OF MOST OF THE HIGHER RESOLUTION MODEL GUIDANCE SUGGESTS THIS ENHANCEMENT WILL BE A SIGNIFICANT PART OF WHATEVER SNOW FALLS...AND SEVERAL RUNS OF THE HRRR ARE PRODUCING PLAUSIBLE SOLUTIONS. THE LIONS SHARE OF SNOW WILL FALL BETWEEN 21Z AND 06Z...WITH MOST LOCATIONS LIKELY TO SEE ONLY A FEW HOURS OF LIGHT TO MODERATE SNOWS SOMEWHERE IN THAT TIMEFRAME. EXPECT AN INCH OR TWO TO FALL EAST OF LAKE ERIE...MAINLY ACROSS THE HIGHER TERRAIN WITH AN ADDED BOOST FROM UPSLOPE FLOW. STEADIER SNOWS WILL FALL EAST OF LAKE ONTARIO...WITH STEADIER SNOWS LIKELY TO DEVELOP THIS AFTERNOON...AND CONTINUE INTO THE EVENING. HRRR GUIDANCE SUGGESTS A BAND OF MODERATE SNOW WILL DEVELOP...WITH A TOTAL OF 2 TO 4 INCHES OF SNOW LIKELY IN THAT REGION THIS AFTERNOON AND EVENING. THIS IS IN LINE WITH THE SEVERAL RUNS OF THE RGEM/NAM. ONE LIMITING FACTOR MAY BE TEMPERATURES...WHICH WILL BE NEAR OR ABOVE FREEZING THROUGH THE EVENT AT LOWER ELEVATIONS...WHICH MAY TEMPER ACCUMULATIONS NEAR LAKE ONTARIO. THE LEAST AMOUNT OF SNOW WILL FALL FROM THE SOUTH SHORE OF LAKE ONTARIO INTO THE FINGER LAKES...WHERE THE LEAST PRECIP AND WARMEST BOUNDARY LAYER TEMPERATURES WILL BE FOUND. SOME OF THESE AREAS MAY SEE NO ACCUMULATION AT ALL. THE FRONT WILL PUSH SOUTH OF THE REGION LATE TONIGHT...WHICH SHOULD BRING DRIER AIR INTO THE REGION. SOME LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES CAN/T BE RULED OUT...BUT WHAT DOES DEVELOP SHOULD BE SHORT LIVED GIVEN THE SHORT FETCH IN THE NORTHERLY FLOW AND THE DRY AIR UPSTREAM. HOWEVER...THIS SET UP IS FAVORABLE FOR CLOUDS TO BE QUITE PERSISTENT BEHIND THE FRONT...AS ANY LAKE MOISTURE GETS TRAPPED BENEATH THE INVERSION. BECAUSE OF THIS...HEDGE ON THE WARM SIDE OF GUIDANCE FOR LOW TEMPERATURES. EXPECT LOWS IN THE LOWER 20S IN MOST LOCATIONS...BUT SIGNIFICANTLY COOLER TEMPERATURES ARE POSSIBLE EAST OF LAKE ONTARIO WHERE CLEARING IS POSSIBLE. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... A QUIET PERIOD IS EXPECTED MONDAY AND TUESDAY WITH A SLOW MODERATING TREND TO CONTINUE THROUGH THE WORK WEEK. FOR MONDAY A FEW FLURRIES OR LIGHT SNOW SHOWERS MAY STILL BE FALLING OFF LAKE ONTARIO SOUTHEAST OF THE LAKE EARLY IN THE MORNING HOURS. TEMPERATURES ALOFT AT 850 HPA UNDER WARM AIR ADVECTION ARE ONLY MARGINAL FOR LAKE EFFECT SNOW...AND WITH LOW LEVEL LIFT ESSENTIALLY GONE AND MOISTURE LACKING FROM WITHIN THE SNOW GROWTH ZONE...ANY SUPPORT FOR LAKE EFFECT SNOW WILL NOT BE CONDUCIVE...THUS ANY LAKE ACTIVITY SHOULD DIMINISH QUICKLY THROUGH THE MORNING. THE 850 HPA RIDGE REMAINS TO OUR WEST TO START THE DAY AND A BROKEN LOW LAYER OF CLOUDS ACROSS HIGHER TERRAIN OF WNY...GENESEE VALLEY AND NORTHERN FINGER LAKES REGION WILL LIKELY START THE DAY. AS THIS RIDGE AXIS PASSES THE AREA FROM WEST TO EAST THROUGH THE MORNING HOURS EXPECT INCREASING AMOUNTS OF SUNSHINE. DESPITE A GOOD DEAL OF SUNSHINE THROUGH THE AFTERNOON HOURS TEMPERATURES WILL HOLD TO AROUND NORMAL ACROSS WESTERN NEW YORK...WITH HIGHS AROUND 30...AND SLIGHTLY BELOW NORMAL ACROSS THE EASTERN LAKE ONTARIO REGION WITH LOW TO MID 20S. MONDAY NIGHT A BROAD AREA OF HIGH PRESSURE WILL BE FOUND ALONG THE ATLANTIC COASTLINE WITH A SOUTHWEST RETURN FLOW ACROSS THE EASTERN GREAT LAKES REGION. THIS WILL PROHIBIT TEMPERATURES FROM PLUNGING...AND IN FACT THEY MAY RISE A DEGREE OR TWO OVERNIGHT ACROSS THE DOWN SLOPE AREAS OF WNY. TOWARDS THE NORTHERN FINGER LAKES AND EASTERN LAKE ONTARIO REGION WHERE THE SOUTHWEST FLOW WILL NOT BE AS GREAT TEMPERATURES WILL FALL BACK INTO THE TEENS TO AROUND 20. TO THE WEST MILDER OVERNIGHT LOWS ARE EXPECTED...WITH LOW 20S ACROSS INTERIOR SOUTHWEST NEW YORK AND UPPER 20S FOR THE LOWER ELEVATIONS. LATE MONDAY NIGHT AND TUESDAY A STORM SYSTEM WILL PASS WELL TO OUR NORTH ACROSS JAMES BAY AND CENTRAL/NORTHERN QUEBEC. A TIGHTENING PRESSURE GRADIENT BETWEEN THIS SYSTEM AND HIGH PRESSURE ALONG THE EASTERN SHORELINE WILL ALLOW WINDS TO BECOME BREEZY THROUGH THE DAY TUESDAY...ESPECIALLY OFF THE LAKES ON A SOUTHWEST FLOW. A FEW CLOUDS WILL LIKELY PASS ACROSS THE REGION THOUGH STILL A GOOD DEAL OF SUNSHINE IS EXPECTED. TEMPERATURES ALOFT AT 850 HPA WILL BE SEVERAL DEGREES WARMER THAN MONDAY...AND WITH THESE SOUTHWEST WINDS TEMPERATURES SHOULD BE A BIT WARMER THAN MONDAY...WITH HIGHS MODERATING INTO THE MID TO UPPER 30S. REMAINING DRY OVERNIGHT THOUGH CLOUDS WILL START TO THICKEN MORE AS A SECOND STORM SYSTEM TAKES A SLIGHTLY MORE SOUTHERN TRACK THROUGH CANADA. LOWS TUESDAY NIGHT WILL FALL BACK INTO THE MID 20S TO AROUND 30 ACROSS THE REGION. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... A GENERAL ZONAL FLOW WILL REMAIN IN PLACE ALONG THE CANADIAN/U.S. BORDER THROUGH THURSDAY. AFTER THAT...A MORE AMPLIFIED FLOW WILL SET UP THURSDAY NIGHT THROUGH SATURDAY AS A DEEPENING TROUGH DIGS INTO THE WESTERN U.S...WHILE A FLAT RIDGE REMAINS IN PLACE OVER EASTERN THIRD OF THE NATION. REGARDING THE FORECAST DETAILS...A WELL DEFINED SHORT WAVE WILL PASS JUST NORTH OF NEW YORK STATE ON WEDNESDAY...BEFORE DRIFTING INTO NORTHERN NEW ENGLAND WEDNESDAY NIGHT. A TIGHT PRESSURE GRADIENT BETWEEN THIS LOW AND HIGH PRESSURE OVER THE SOUTHEAST WILL AGAIN MAKE FOR A BREEZY TO WINDY DAY ACROSS THE REGION. EXPECT WIND GUSTS TO BE STRONGER WEDNESDAY THAN TUESDAY...WITH THE LOW CLOSER TO THE REGION. A FEW GUSTS MAY APPROACH 40 TO 45 MPH IN TRADITIONALLY GUSTY AREAS OF THE CWA. A WEAK FRONT THAT IS ASSOCIATED WITH THIS IMPULSE WILL DROP SOUTH ACROSS NEW YORK STATE WEDNESDAY NIGHT...BUT THE FRONT WILL NOT HAVE MUCH MOISTURE TO WORK WITH. WILL HAVE LOW CHC POPS EAST OF LAKE ONTARIO WHERE SOME LAKE ENHANCEMENT TO THE PRECIPITATION MIGHT OCCUR. OTHERWISE EXPECT THE REGION TO REMAIN DRY. ON THURSDAY...THE GFS AND ECMWF ARE IN BETTER AGREEMENT REGARDING THE MOVEMENT OF THE CLOSED LOW THAT WILL BE LIFTING OUT OF THE SOUTHERN PLAINS. THE GFS IS STILL A LITTLE FASTER IN LIFTING THE UPPER LOW OUT...BUT THE GENERAL TREND IS THAT ANY PCPN ASSOCIATED WITH THE APPROACHING LOW MAY DELAYED UNTIL THURSDAY NIGHT. THE SLOWER MOVEMENT OF THE LOW ALSO MEANS THAT IT WILL TAKE LONGER THE FOR BOUNDARY LAYER TEMPERATURES TO MODERATE. THIS MAY RESULT IN A BETTER CHANCE FOR LIGHT SNOW AT THE ONSET OF THE PCPN. ON FRIDAY...THE UPPER LOW WILL WEAKEN AS IT ENCOUNTERS THE FLAT RIDGE THAT WILL STILL BE IN PLACE OVER THE EASTERN PART OF THE NATION. BY SATURDAY...THE ECMWF TAKES THE ASSOCIATED SURFACE LOW AND MERGES IT WITH A DEEPER LOW THAT WILL BE LIFTING NORTH ACROSS JAMES BAY. SINCE THE SURFACE LOW IS FORECAST TO STAY TO OUR WEST...A MILD SOUTHWEST FLOW WILL PREVAIL ACROSS THE AREA. THIS WILL LIKELY CAUSE MOST PCPN TO FALL AS RAIN ON FRIDAY AND SATURDAY. THE MODERATING TREND DURING THIS PERIOD WILL PUSH TEMPERATURES INTO THE LOWER TO MID 40S ACROSS MOST OF THE AREA ON FRIDAY AND SATURDAY. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... EXPECT MAINLY MVFR CONDITIONS ACROSS WESTERN NY WITH WIDESPREAD LIGHT/WET SNOW MIXED WITH RAIN AT TIMES. THERE MAY BE A FEW BRIEF PERIODS OF IFR IN THE SOMEWHAT STEADIER SNOW. MVFR CIGS HAVE ALSO SPREAD INTO MUCH OF THE AREA...AND THESE WILL CONTINUE THIS AFTERNOON. AFTER THIS...A FRONTAL BOUNDARY AND UPPER LEVEL TROF WILL BRING A PERIOD OF SNOW TO MOST TAF LOCATIONS...WITH THIS LIKELY TO RESULT VSBY OF 2SM OR LOWER...AND IFR CONDITIONS. THE LOWEST CONDITIONS WILL BE AT JHW/ART...WITH LIGHTER SNOWFALL RATES EXPECTED AT IAG/ROC. CONFIDENCE IN TIMING IS MODERATE...GIVEN GOOD MODEL AGREEMENT IN THE PATTERN...HOWEVER IT IS POSSIBLE IFR CIGS MAY BUILD IN AHEAD OF THE SNOW IN THE SOUTHWEST FLOW. CIGS SHOULD MAINLY LIFT BEHIND THE FRONT...BUT MAY BRIEFLY LOWER IMMEDIATELY PRECEDING THE FRONTAL PASSAGE DURING THE EVENING HOURS. AFTER THIS...CLOUDS WILL PROBABLY SCATTER NEAR THE LAKES...BUT PERSISTENT MVFR CIGS ARE MORE LIKELY INLAND. OUTLOOK... MONDAY AND TUESDAY...VFR. WEDNESDAY...MAINLY VFR. THURSDAY...VFR/MVFR WITH A CHANCE OF RAIN SHOWERS. && .MARINE... LOW PRESSURE ACROSS THE CENTRAL LAKES WILL LIFT UP THE SAINT LAWRENCE VALLEY LATER TODAY. THIS WILL RESULT IN A DECENT SOUTHWEST FLOW AND SMALL CRAFT CONDITIONS TODAY AND INTO TONIGHT. WINDS WILL SHIFT TO THE NORTH AS AN ASSOCIATED COLD FRONT DROPS ACROSS THE WATERS TONIGHT. THEN HIGH PRESSURE WILL BUILD ACROSS THE WATERS MONDAY...WITH DIMINISHING WINDS. AS THE HIGH SLIDES EAST...A TIGHTENING PRESSURE GRADIENT MAY REQUIRE SMALL CRAFT ADVISORIES AGAIN MID-WEEK IN A SOUTHWESTERLY FLOW. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LEZ040-041. SMALL CRAFT ADVISORY UNTIL 9 PM EST THIS EVENING FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR LOZ043-044. SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LOZ042-045. && $$ SYNOPSIS...APFFEL NEAR TERM...APFFEL/HITCHCOCK SHORT TERM...THOMAS LONG TERM...THOMAS/TJP AVIATION...APFFEL/HITCHCOCK MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
741 AM EST SUN JAN 6 2013 .SYNOPSIS... A WEAK AREA OF LOW PRESSURE WILL BRING MINOR SNOW ACCUMULATIONS TO MOST LOCATIONS THIS AFTERNOON AND EVENING...BUT SNOWS WILL BE A BIT STEADIER EAST OF LAKE ONTARIO. HIGH PRESSURE WILL THEN BUILD INTO THE OHIO VALLEY AND EASTERN GREAT LAKES FOR THE FIRST HALF OF NEXT WEEK WITH DRY WEATHER AND WARMING TEMPERATURES. THE JANUARY THAW WILL LAST RIGHT THROUGH NEXT WEEKEND WITH MILD TEMPERATURES AND INCREASING CHANCES OF RAIN. && .NEAR TERM /THROUGH TONIGHT/... A SHORTWAVE EXITING TO THE EAST HAS LEFT WESTERN NEW YORK IN NO MANS LAND OF SORT. THERE ARE SOME LIGHT LAKE ENHANCED RAIN AND SNOW SHOWERS NORTHEAST OF LAKE ERIE...OTHERWISE THE MAJORITY OF THE REGION IS DRY. THIS PATTERN SHOULD CONTINUE THROUGH THE MORNING HOURS. THE FINGER LAKES AND GENESEE VALLEY MAY GET SOME BREAKS OF SUN...WHICH WOULD HELP TEMPERATURES WARM A BIT. EXPECT HIGHS IN THE UPPER 30S IN MOST LOCATIONS...WITH LOWER 40S IN SPOTS WHICH GET SOME SUN. THE MORE SIGNIFICANT PART OF THIS GENERALLY WEAK SYSTEM WILL IMPACT THE REGION DURING THE AFTERNOON AND EVENING HOURS. THE KEY WILL BE THE PASSAGE OF A SHORT WAVE...WHICH WILL HELP DRIVE A COLD FRONT ACROSS THE REGION. HOWEVER...THERE WILL BE WELL ALIGNED SOUTHWEST FLOW AHEAD OF THIS...WITH AMPLE MOISTURE AND A LONG FETCH. 850 MB TEMPERATURES WILL ONLY BE AROUND -7C...WITH LAKE INDUCED CAPES BARELY MEASURABLE. HOWEVER...THIS WILL PROBABLY BE ENOUGH TO BOOST MOISTURE A BIT...AND BRING A PERIOD OF SNOW TO MOST LOCATIONS. THE QPF FORECAST OF MOST OF THE HIGHER RESOLUTION MODEL GUIDANCE SUGGESTS THIS ENHANCEMENT WILL BE A SIGNIFICANT PART OF WHATEVER SNOW FALLS...AND SEVERAL RUNS OF THE HRRR ARE PRODUCING PLAUSIBLE SOLUTIONS. THE LIONS SHARE OF SNOW WILL FALL BETWEEN 18Z AND 06Z...WITH MOST LOCATIONS LIKELY TO SEE ONLY A FEW HOURS OF LIGHT TO MODERATE SNOWS SOMEWHERE IN THAT TIMEFRAME. EXPECT AN INCH OR TWO TO FALL EAST OF LAKE ERIE. STEADIER SNOWS WILL FALL EAST OF LAKE ONTARIO...WITH STEADIER SNOWS LIKELY TO DEVELOP THIS AFTERNOON...AND CONTINUE INTO THE EVENING. HRRR GUIDANCE SUGGESTS A BAND OF MODERATE SNOW WILL DEVELOP...WITH A TOTAL OF 2 TO 4 INCHES OF SNOW LIKELY IN THAT REGION THIS AFTERNOON AND EVENING. THIS IS IN LINE WITH THE SEVERAL RUNS OF THE RGEM/NAM. THE EASTERN LAKE ONTARIO REGION...WITH THE SOUTHWEST FLOW...AND MODEL QPF FORECASTS SUGGESTING THIS FORECAST WILL APPLY TO THE CITY OF WATERTOWN AND ALL OF JEFFERSON COUNTY. WILL HAVE TO WATCH THIS POTENTIAL BAND...WITH THE POSSIBILITY THAT AN ADVISORY WILL BE REQUIRED. ONE LIMITING FACTOR MAY BE TEMPERATURES...WHICH WILL BE NEAR OR ABOVE FREEZING THROUGH THE EVENT. LESSER AMOUNTS WILL FALL FURTHER FROM THE LAKE IN ROCHESTER...GENESEE VALLEY...AND FINGER LAKES REGIONS. THE FRONT WILL PUSH SOUTH OF THE REGION LATE TONIGHT...WHICH SHOULD BRING DRIER AIR INTO THE REGION. SOME LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES CAN/T BE RULED OUT...BUT WHAT DOES DEVELOP SHOULD BE SHORT LIVED GIVEN THE SHORT FETCH IN THE NORTHERLY FLOW AND THE DRY AIR UPSTREAM. HOWEVER...THIS SET UP IS FAVORABLE FOR CLOUDS TO BE QUITE PERSISTENT BEHIND THE FRONT...AS ANY LAKE MOISTURE GETS TRAPPED BENEATH THE INVERSION. BECAUSE OF THIS...HEDGE ON THE WARM SIDE OF GUIDANCE FOR LOW TEMPERATURES. EXPECT LOWS IN THE LOWER 20S IN MOST LOCATIONS...BUT SIGNIFICANTLY COOLER TEMPERATURES ARE POSSIBLE EAST OF LAKE ONTARIO WHERE CLEARING IS POSSIBLE. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... A QUIET PERIOD IS EXPECTED MONDAY AND TUESDAY WITH A SLOW MODERATING TREND TO CONTINUE THROUGH THE WORK WEEK. FOR MONDAY A FEW FLURRIES OR LIGHT SNOW SHOWERS MAY STILL BE FALLING OFF LAKE ONTARIO SOUTHEAST OF THE LAKE EARLY IN THE MORNING HOURS. TEMPERATURES ALOFT AT 850 HPA UNDER WARM AIR ADVECTION ARE ONLY MARGINAL FOR LAKE EFFECT SNOW...AND WITH LOW LEVEL LIFT ESSENTIALLY GONE AND MOISTURE LACKING FROM WITHIN THE SNOW GROWTH ZONE...ANY SUPPORT FOR LAKE EFFECT SNOW WILL NOT BE CONDUCIVE...THUS ANY LAKE ACTIVITY SHOULD DIMINISH QUICKLY THROUGH THE MORNING. THE 850 HPA RIDGE REMAINS TO OUR WEST TO START THE DAY AND A BROKEN LOW LAYER OF CLOUDS ACROSS HIGHER TERRAIN OF WNY...GENESEE VALLEY AND NORTHERN FINGER LAKES REGION WILL LIKELY START THE DAY. AS THIS RIDGE AXIS PASSES THE AREA FROM WEST TO EAST THROUGH THE MORNING HOURS EXPECT INCREASING AMOUNTS OF SUNSHINE. DESPITE A GOOD DEAL OF SUNSHINE THROUGH THE AFTERNOON HOURS TEMPERATURES WILL HOLD TO AROUND NORMAL ACROSS WESTERN NEW YORK...WITH HIGHS AROUND 30...AND SLIGHTLY BELOW NORMAL ACROSS THE EASTERN LAKE ONTARIO REGION WITH LOW TO MID 20S. MONDAY NIGHT A BROAD AREA OF HIGH PRESSURE WILL BE FOUND ALONG THE ATLANTIC COASTLINE WITH A SOUTHWEST RETURN FLOW ACROSS THE EASTERN GREAT LAKES REGION. THIS WILL PROHIBIT TEMPERATURES FROM PLUNGING...AND IN FACT THEY MAY RISE A DEGREE OR TWO OVERNIGHT ACROSS THE DOWN SLOPE AREAS OF WNY. TOWARDS THE NORTHERN FINGER LAKES AND EASTERN LAKE ONTARIO REGION WHERE THE SOUTHWEST FLOW WILL NOT BE AS GREAT TEMPERATURES WILL FALL BACK INTO THE TEENS TO AROUND 20. TO THE WEST MILDER OVERNIGHT LOWS ARE EXPECTED...WITH LOW 20S ACROSS INTERIOR SOUTHWEST NEW YORK AND UPPER 20S FOR THE LOWER ELEVATIONS. LATE MONDAY NIGHT AND TUESDAY A STORM SYSTEM WILL PASS WELL TO OUR NORTH ACROSS JAMES BAY AND CENTRAL/NORTHERN QUEBEC. A TIGHTENING PRESSURE GRADIENT BETWEEN THIS SYSTEM AND HIGH PRESSURE ALONG THE EASTERN SHORELINE WILL ALLOW WINDS TO BECOME BREEZY THROUGH THE DAY TUESDAY...ESPECIALLY OFF THE LAKES ON A SOUTHWEST FLOW. A FEW CLOUDS WILL LIKELY PASS ACROSS THE REGION THOUGH STILL A GOOD DEAL OF SUNSHINE IS EXPECTED. TEMPERATURES ALOFT AT 850 HPA WILL BE SEVERAL DEGREES WARMER THAN MONDAY...AND WITH THESE SOUTHWEST WINDS TEMPERATURES SHOULD BE A BIT WARMER THAN MONDAY...WITH HIGHS MODERATING INTO THE MID TO UPPER 30S. REMAINING DRY OVERNIGHT THOUGH CLOUDS WILL START TO THICKEN MORE AS A SECOND STORM SYSTEM TAKES A SLIGHTLY MORE SOUTHERN TRACK THROUGH CANADA. LOWS TUESDAY NIGHT WILL FALL BACK INTO THE MID 20S TO AROUND 30 ACROSS THE REGION. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... A GENERAL ZONAL FLOW WILL REMAIN IN PLACE ALONG THE CANADIAN/U.S. BORDER THROUGH THURSDAY. AFTER THAT...A MORE AMPLIFIED FLOW WILL SET UP THURSDAY NIGHT THROUGH SATURDAY AS A DEEPENING TROUGH DIGS INTO THE WESTERN U.S...WHILE A FLAT RIDGE REMAINS IN PLACE OVER EASTERN THIRD OF THE NATION. REGARDING THE FORECAST DETAILS...A WELL DEFINED SHORT WAVE WILL PASS JUST NORTH OF NEW YORK STATE ON WEDNESDAY...BEFORE DRIFTING INTO NORTHERN NEW ENGLAND WEDNESDAY NIGHT. A TIGHT PRESSURE GRADIENT BETWEEN THIS LOW AND HIGH PRESSURE OVER THE SOUTHEAST WILL AGAIN MAKE FOR A BREEZY TO WINDY DAY ACROSS THE REGION. EXPECT WIND GUSTS TO BE STRONGER WEDNESDAY THAN TUESDAY...WITH THE LOW CLOSER TO THE REGION. A FEW GUSTS MAY APPROACH 40 TO 45 MPH IN TRADITIONALLY GUSTY AREAS OF THE CWA. A WEAK FRONT THAT IS ASSOCIATED WITH THIS IMPULSE WILL DROP SOUTH ACROSS NEW YORK STATE WEDNESDAY NIGHT...BUT THE FRONT WILL NOT HAVE MUCH MOISTURE TO WORK WITH. WILL HAVE LOW CHC POPS EAST OF LAKE ONTARIO WHERE SOME LAKE ENHANCEMENT TO THE PRECIPITATION MIGHT OCCUR. OTHERWISE EXPECT THE REGION TO REMAIN DRY. ON THURSDAY...THE GFS AND ECMWF ARE IN BETTER AGREEMENT REGARDING THE MOVEMENT OF THE CLOSED LOW THAT WILL BE LIFTING OUT OF THE SOUTHERN PLAINS. THE GFS IS STILL A LITTLE FASTER IN LIFTING THE UPPER LOW OUT...BUT THE GENERAL TREND IS THAT ANY PCPN ASSOCIATED WITH THE APPROACHING LOW MAY DELAYED UNTIL THURSDAY NIGHT. THE SLOWER MOVEMENT OF THE LOW ALSO MEANS THAT IT WILL TAKE LONGER THE FOR BOUNDARY LAYER TEMPERATURES TO MODERATE. THIS MAY RESULT IN A BETTER CHANCE FOR LIGHT SNOW AT THE ONSET OF THE PCPN. ON FRIDAY...THE UPPER LOW WILL WEAKEN AS IT ENCOUNTERS THE FLAT RIDGE THAT WILL STILL BE IN PLACE OVER THE EASTERN PART OF THE NATION. BY SATURDAY...THE ECMWF TAKES THE ASSOCIATED SURFACE LOW AND MERGES IT WITH A DEEPER LOW THAT WILL BE LIFTING NORTH ACROSS JAMES BAY. SINCE THE SURFACE LOW IS FORECAST TO STAY TO OUR WEST...A MILD SOUTHWEST FLOW WILL PREVAIL ACROSS THE AREA. THIS WILL LIKELY CAUSE MOST PCPN TO FALL AS RAIN ON FRIDAY AND SATURDAY. THE MODERATING TREND DURING THIS PERIOD WILL PUSH TEMPERATURES INTO THE LOWER TO MID 40S ACROSS MOST OF THE AREA ON FRIDAY AND SATURDAY. && .AVIATION /13Z SUNDAY THROUGH THURSDAY/... EXPECT MAINLY MVFR CONDITIONS DUE TO CEILINGS THROUGH THIS MORNING AS AN INITIAL DISTURBANCE EXITS TO THE EAST. BRIEF BREAKS TO VFR ARE POSSIBLE...IN AND OUT OF SUBTLE WAVES OF MOISTURE. AFTER THIS...A FRONTAL BOUNDARY AND UPPER LEVEL TROF WILL BRING A PERIOD OF SNOW TO MOST TAF LOCATIONS...WITH THIS LIKELY TO RESULT VSBY OF 2SM OR LOWER...AND IFR CONDITIONS. THE LOWEST CONDITIONS WILL BE AT JHW/ART...WITH LIGHTER SNOWFALL RATES EXPECTED AT IAG/ROC. CONFIDENCE IN TIMING IS MODERATE...GIVEN GOOD MODEL AGREEMENT IN THE PATTERN...HOWEVER IT IS POSSIBLE IFR CIGS MAY BUILD IN AHEAD OF THE SNOW IN THE SOUTHWEST FLOW. CIGS SHOULD MAINLY LIFT BEHIND THE FRONT...BUT MAY BRIEFLY LOWER IMMEDIATELY PRECEDING THE FRONTAL PASSAGE DURING THE EVENING HOURS. AFTER THIS...CLOUDS WILL PROBABLY SCATTER NEAR THE LAKES...BUT PERSISTENT MVFR CIGS ARE MORE LIKELY INLAND. OUTLOOK... MONDAY AND TUESDAY...VFR. WEDNESDAY...MAINLY VFR. THURSDAY...VFR/MVFR WITH A CHANCE OF RAIN SHOWERS. && .MARINE... LOW PRESSURE ACROSS THE CENTRAL LAKES WILL LIFT UP THE SAINT LAWRENCE VALLEY LATER TODAY. THIS WILL RESULT IN A DECENT SOUTHWEST FLOW AND SMALL CRAFT CONDITIONS TODAY AND INTO TONIGHT. WINDS WILL SHIFT TO THE NORTH AS AN ASSOCIATED COLD FRONT DROPS ACROSS THE WATERS TONIGHT. THEN HIGH PRESSURE WILL BUILD ACROSS THE WATERS MONDAY...WITH DIMINISHING WINDS. AS THE HIGH SLIDES EAST...A TIGHTENING PRESSURE GRADIENT MAY REQUIRE SMALL CRAFT ADVISORIES AGAIN MID-WEEK IN A SOUTHWESTERLY FLOW. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LEZ040-041. SMALL CRAFT ADVISORY UNTIL 9 PM EST THIS EVENING FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR LOZ043-044. SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LOZ042-045. && $$ SYNOPSIS...APFFEL NEAR TERM...APFFEL SHORT TERM...THOMAS LONG TERM...THOMAS/TJP AVIATION...APFFEL MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1048 PM EST MON JAN 7 2013 .SYNOPSIS... CLOUDS WILL INCREASE TONIGHT IN ASSOCIATED WITH A COASTAL TROUGH. IT WILL REMAIN FAIRLY CLOUDY THROUGH THE MIDWEEK ALTHOUGH TEMPERATURES WILL BE ON THE INCREASE ESPECIALLY AS A WARM FRONT LIFTS THROUGH THURSDAY. WARM AND RAIN FREE WEATHER WILL LAST THROUGH THE WEEKEND. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... AS OF 1035 PM MONDAY...MID TO HIGH LEVEL CLOUDS CONTINUE TO EXPAND NORTHWARD ACROSS THE FA THIS EVENING AND OVERNIGHT...WITH A LOW DECK POSSIBLE ALONG THE IMMEDIATE COAST AS LATEST HRRR MODEL INDICATES AN INVERTED SFC TROF TO DEVELOP JUST OFFSHORE LATE TONIGHT. OVERNIGHT TEMPS/DEWPOINTS CONTINUE TO BE MASSAGED...MOSTLY TOWARD THE UPWARD SIDE DUE TO INCREASING OPAQUE SKY COVER. WINDS ACROSS THE INLAND COUNTIES WILL HAVE THE POTENTIAL TO DECOUPLE AS THE CENTER OF THE SFC HIGH EXTENDS ACROSS THIS AREA. COULD OBSERVE NEAR FREEZING READINGS IF RAD COOLING CONDITIONS PERSIST THROUGH THE OVERNIGHT. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...AS WEDGE OF HIGH PRESSURE HANGS ON AT THE SURFACE IN A WEDGE-LIKE SCENARIO THE MAIN FORECAST ISSUE ON TUES SEEMS TO BE THE EXTENT OF CLOUD COVER THAT MANAGES TO DEVELOP. E TO NE WINDS BENEATH WARM ADVECTION/SW FLOW AT 850 MB LEADS TO A NEARLY ISOTHERMAL LAYER FROM VERY ROUGHLY 950-850MB WITH FAIRLY HIGH RH. ABOVE THIS LAYER IS VERY DRY AIR ASSOCIATED WITH SUBSIDENCE INVERSION. ACTUAL MIXING IS FORECAST TO BE QUITE SHALLOW SO THIS DRY AIR MAY NOT COME TO BEAR TOO MUCH WITH RESPECT TO CLOUD COVER OBSERVED AT THE SURFACE...I JUST WONDER IF GUIDANCE IS BRINGING IN TOO MUCH MOISTURE OFF OF THE ATLANTIC. THE ACTUAL FRONTAL BAND SHOULD NOT MAKE IT THIS FAR NORTH AND WEST AND GUIDANCE IS IN FAIRLY GOOD AGREEMENT THAT LOW LEVEL ISENTROPIC UPGLIDE IS VERY SLOW OR EVEN NOT FORECAST TO DEVELOP UNTIL NIGHTTIME. SHOW A GRADUAL UPWARD TREND IN SKY COVER BUT WILL CAP VALUES NEAR UPPER RANGES OF PARTLY CLOUDY SAVE FOR SOUTHERN ZONES WHICH WILL REGISTER MOSTLY CLOUDY IN TEXT PRODUCTS IN ALL LIKELIHOOD. SMALL POPS HINTED AT IN GUIDANCE SEEMS IMPLAUSIBLE DUE TO AFOREMENTIONED DRY AIR. DRIZZLE SEEMS LIKE WORST CASE. BY WEDNESDAY THE HIGH SHOWS VERY LITTLE MOVEMENT BUT WEAKENS SUFFICIENTLY TO NO LONGER IMPLY COOL AIR WEDGING. MIXING IS FORECAST TO REMAIN QUITE SHALLOW AND SO SOME OF THE LOW LEVEL WARM AIR ADVECTION MAY NOT BE REALIZED AT THE SURFACE (ESPECIALLY IF THE CLOUD COVER CONTINUES TO INCREASE). BASED UPON THIS AND SIMILAR CONCERN NOTED BY SOME NEIGHBORS HAVE TRIMMED WED HIGHS A FEW DEGREES BELOW GUIDANCE. MOISTURE PROFILE A LITTLE DEEPER IN FORECAST SOUNDINGS BUT RAIN CHANCES WILL STAY CAPPED AT SLIGHT CHANCE IN THE ABSENCE OF ANY REAL FORCING MECHANISM. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 3 PM MONDAY...MAIN DETAILS OF THE SYNOPTIC PATTERN FOR THE EXTENDED REMAIN IN PLACE THIS AFTERNOON AS A STRONG CLOSED LOW WILL MOVE QUICKLY THROUGH THE MIDWEST AND SHEAR OUT. THE FLOW BETWEEN THIS FEATURE AND AN ANOMALOUS RIDGE TO THE SOUTHEAST WILL CREATE A VERY WARM AND PERSISTENT FLOW. THE LOW...BEFORE SHEARING OUT AND FILLING IS 3-4 STAND DEVIATIONS BELOW NORMAL AND THE RIDGE IS 1-2 ABOVE. 850MB TEMPERATURES OF 13-15 DEGREES C WILL ADVECT INTO THE AREA FOR THE WEEKEND. MEX GUIDANCE IS ADVERTISING WIDESPREAD 70S FOR THE THIRD DAY IN A ROW AND THE FORECAST HAS BEEN ADJUSTED UPWARD AS EVEN THE COOLER HPC NUMBERS ARE MOSTLY IN THE 70S FOR THE WEEKEND. THE ONLY RECORD THAT APPEARS IN JEOPARDY AT THIS TIME IS FLORENCE FOR SATURDAY WHICH IS 73 DEGREES. THE KICKER SYSTEM...THE ONE THAT FORCES THE INITIAL DEEP LOW TO MOVE OUT BEGINS TO IMPACT THE REGION MONDAY WITH INCREASED CLOUDINESS AND SLIGHT CHANCE POPS HENCE...SLIGHTLY COOLER TEMPERATURES. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/... AS OF 00Z...INCREASING HIGH CLOUDS TO THE SOUTH COULD GIVE US SOME BROKEN CONDITIONS TONIGHT...ESPECIALLY OVER THE SOUTHERN TERMINALS. A WEAK COASTAL TROUGH TRIES TO DEVELOP TONIGHT. THIS COULD BRING SOME POSSIBLE MVFR STRATA CU ALONG THE COAST...BUT WILL KEEP IT SCATTERED FOR THE PRESENT TIME. TUESDAY...RETURN FLOW AROUND HIGH PRESSURE CENTERED OFFSHORE WILL GIVE US MAINLY LIGHT EASTERLY FLOW. MODERATE CHANCE OF A VFR STRATA CU CEILING DEVELOPING AROUND MID MORNING...POSSIBLY CONTINUING THROUGH THE END OF THE FORECAST PERIOD. EXTENDED OUTLOOK...POSSIBLE MVFR/IFR CIGS/VSBYS WEDNESDAY ASSOCIATED WITH A COASTAL TROUGH. SLIGHT CHANCE OF SHOWERS WEDNESDAY AND THURSDAY. VFR DEVELOPING FRIDAY AND PERSISTING THROUGH SATURDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1035 PM MONDAY...CENTER OF SFC HIGH TO SLIDE OFFSHORE FROM THE MID-ATLANTIC STATES OVERNIGHT INTO TUESDAY...BUT WILL CONTINUE TO RIDGE BACK ACROSS THE AREA WATERS. INVERTED SFC TROF TO DEVELOP OFFSHORE AND PARALLEL TO THE CAROLINA COASTLINES TONIGHT AND PERSIST INTO TUESDAY. LOOK FOR WINDS TO BACK FROM AN ENE DIRECTION TO NE...WITH WIND SPEEDS BASICALLY AROUND 15 KT...EXCEPT UP TO 20 KT OUTER WATERS OFF CAPE FEAR. SIGNIFICANT SEAS WILL RANGE FROM 2 TO 4 FT...EXCEPT UP TO 5 FT OUTER WATERS OFF CAPE FEAR...AND OUTER WATERS OFF THE MOUTH OF WINYAH BAY. SIGNIFICANT SEAS WILL PRIMARILY CONSIST OF WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS. SHORT TERM/TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY ...WEDGE-LIKE HIGH PRESSURE IN PLACE ON TUESDAY TO BRING A LIGHT NE FLOW...GENERALLY IN THE 10 TO 15 KT RANGE. SEAS 2 TO 3 FT IN A PREDOMINANT 5 SECOND WIND CHOP. ON WEDNESDAY THE HIGH BOTH WEAKENS AND MOVES EVER SO SLIGHTLY TO THE N. WINDS MAY VEER TO EASTERLY WHILE THEY DROP TO ABOUT 10 KT. THIS WILL CUT OUT THE 3 FT SEAS AND MOST PLACES WILL BE CAPPED AT 2 FT. DOMINANT PERIOD LIKELY STAYS ABOUT 5 OR 6 SECONDS BUT A VERY SMALL 10 SECOND EASTERLY SWELL IS ALSO FORECAST. LONG TERM/THURSDAY THROUGH FRIDAY/... AS OF 3 PM MONDAY...MAIN EVENT FOR THE MARINE COMMUNITY WILL BE THE WIND SHIFT OCCURRING FRIDAY MORNING AS A WARM FRONT MOVES ACROSS. CONFIDENCE IS NOT ALL THAT GREAT AT LEAST IN REGARDS TO TIMING AS MEDIUM RANGE GUIDANCE HAS BEEN JUMPING AROUND SOMEWHAT. EXPECT A GRADUAL VEERING FROM NORTHEAST THURSDAY AFTERNOON TO SOUTH BY FRIDAY AT 1200 UTC. SPEEDS REMAIN MARGINAL WITH 10-15 KNOTS. EXPECT MORE WESTERLY WINDS SATURDAY COURTESY OF A GLANCING SHOT FROM A BACKDOOR FRONT. SIGNIFICANT SEAS LOOK FAIRLY CONSISTENT WITH THE WAVEWATCH STILL A BIT ON THE HIGH SIDE. THERE COULD STILL BE A SCEC HEADLINE ESPECIALLY EARLY BUT THE WIND SHIFT SHOULD PRECLUDE A SMALL CRAFT ADVISORY WITH 3-5 FEET EXPECTED. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...MBB NEAR TERM...DCH SHORT TERM...MBB LONG TERM...SHK AVIATION...DL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1055 AM EST SUN JAN 6 2013 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE WILL CROSS THE THE MIDDLE ATLANTIC STATES TODAY...FOLLOWED BY THE PASSAGE OF A DRY COLD FRONT TONIGHT. HIGH PRESSURE WILL BUILD INTO...AND REMAIN OVER OUR REGION...THROUGH TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1055 AM SUNDAY... AN AREA OF OF LIGHT RAIN FALLING FROM CEILINGS IN THE 3-6KFT RANGE ACROSS THE SOUTHEASTERN HALF OF THE RAH CWA WILL SHIFT EAST DURING THE NEXT FEW HOURS. THE KGSO RAOB THIS MORNING WAS NOTABLY DRIER AND WARMER IN THE LOWEST ~5KFT COMPARED TO RECENT NAM/GFS FCST BUFR SOUNDINGS AND NOTED MULTIPLE LAYERS OF DRYING ALOFT. RECENT VIS SAT IMAGES HAVE INDICATED SOME EASTWARD ADVANCEMENT OF THE AREA OF THINNING CLOUDS IN THE FOOTHILLS WHILE THE REMAINDER OF THE RAH CWA IS BLANKETED IN OVERCAST SKIES. EXPECT MOSTLY CLOUDY/CLOUDY SKIES TO PERSIST FOR THE REMAINDER OF THE DAY WITH AREAS OF VERY LIGHT PRECIPITATION ACROSS THE SOUTHERN/SOUTHEAST TIER. AFTER THE INITIAL AREA OF RAIN OVER THE AREA WANES FOR A FEW HOURS AROUND/JUST AFTER MIDDAY...ANOTHER AREA OF PATCHY LIGHT RAIN IS EXPECTED TO DEVELOP ACROSS SC AND SPREAD INTO THE FAR SOUTHERN PIEDMONT..THE SOUTHERN SANDHILLS AND THE SOUTHERN COASTAL PLAIN. THIS AREA OF RAIN IS EXPECTED TO BE GENERATED THROUGH LOW LEVEL MOISTURE ADVECTION AND SHALLOW LIFT WITH THE GFS AND TO A LESSER EXTENT THE NAM INDICATING SOME LIGHT QPF. THE HIGH RES CONVECTION ALLOWING MODELS...ESPECIALLY THE HRRR HAVE BEEN BULLISH ON ANOTHER SURGE OF PRECIPITATION BUT THE PAST RUN OR TWO HAVE BACKED OFF A BIT. WOULD NOT CATEGORIZE THE DAY AS A WASHOUT AS QPF VALUES WILL ONLY BE ON THE ORDER OF A FEW HUNDREDTHS OF AN INCH. TEMPERATURES WILL BE MODULATED A GREAT DEAL BY THE CLOUDS AND PRECIPITATION WITH HIGHS IN THE LOWER 50S ACROSS THE WEST/NORTHWEST PARTS OF FORECAST AREA TO THE UPPER 40S/NEAR 50 EAST. -BLAES TONIGHT: A POTENT NORTHERN STREAM S/W TROUGH AND ASSOCIATED SURFACE COLD FRONT WILL SWEEP EASTWARD ACROSS CENTRAL NC. A RENEWED AREA OF MID CLOUDS...AND LINGERING JET CIRRUS MAY ACCOMPANY THE S/W THROUGH 06Z...BUT STRONG SUBSIDENCE AND RAPID CLEARING/DRYING WILL COMMENCE THEREAFTER. POST-FRONTAL...CAA-DRIVEN LOWS IN THE UPPER 20S TO LOWER-MIDDLE 30S. -MWS && .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 320 AM SUNDAY... MODIFIED CONTINENTAL POLAR HIGH PRESSURE WILL BUILD ACROSS AND LINGER OVER THE MIDDLE ATLANTIC AND CAROLINAS THIS PERIOD... ASSOCIATED NORTHEASTERLY FLOW DURING THE DAY...AND NIGHTTIME CALM...WILL RESULT IN BELOW AVERAGE TEMPERATURES IN THE UPPER 40S TO AROUND 50 AND UPPER 20S...RESPECTIVELY...THE LATTER OF WHICH SHOULD OCCUR DESPITE INCREASING CIRRUS OVERNIGHT. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 258 AM SUNDAY... MODEL SOLUTIONS COMING TOGETHER WITH THE TRACK OF THE LOW LATE IN THE WEEK... MOVING FROM TX ON THURS INTO THE GREAT LAKES FRI. GFS AND ECMWF STILL SHOWING THE TAIL END OF A NORTHERN STREAM COLD FRONT ENTERING THE REGION ON THURSDAY... WITH BACKED WINDS BRIEFLY INDICATED ON FORECAST SOUNDINGS... BEFORE A WARM FRONT SURGES NORTH ON FRIDAY. THE ASSOCIATED COLD FRONT WILL JUST ENTER THE REGION OVERNIGHT FRIDAY INTO SATURDAY... BEFORE WASHING OUT. TEMPS WILL BE HIGHLY DEPENDENT ON THE TIMING AND MOVEMENT OF THESE FRONTAL ZONES IN THE LATTER PART OF THE WEEK... BUT WILL CONTINUE TO KEEP HIGHS IN THE 60S... WITH LOWS IN THE 40S. PRECIPITATION DOES NOT APPROACH THE AREA UNTIL LATER IN THE DAY ON THURSDAY... AND LINGERS THROUGH FRIDAY. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... AS OF 650 AM SUNDAY... PERIODS OF LIGHT RAIN OR SPRINKLES WILL CONTINUE MAINLY EAST OF KRDU (IE. AT KRWI AND KFAY) THROUGH AROUND SUNSET. A PERIOD OF MVFR CEILINGS WILL LIKELY ACCOMPANY THE THIS LIGHT PRECIPITATION DURING THE AFTERNOON...PARTICULARLY AT KFAY. A DRY COLD FRONT AND ASSOCIATED TRAILING CLEAR SKIES AND SURFACE WIND SHIFT TO NORTHWESTERLY WILL SWEEP EASTWARD ACROSS CENTRAL NC BETWEEN 03-09Z. OUTLOOK: RETURN SOUTHWESTERLY FLOW WILL PROMOTE AN INCREASING LIKELIHOOD OF SUB-VFR CEILINGS AT KFAY TUE AFT...AND ACROSS THE REMAINDER OF CENTRAL NC TERMINALS TUE NIGHT. SUB-VFR CONDITIONS AND A CHANCE OF SHOWERS WILL THEN RETURN FOR LATE THU. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MWS NEAR TERM...BLAES/MWS SHORT TERM...MWS LONG TERM...SEC AVIATION...MWS
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
910 PM CST MON JAN 7 2013 .DISCUSSION... MAIN CHANGE THIS EVE WAS TO KEEP CLOUDS IN NORTHEAST PART OF THE FCST AREA IN A BIT LATER. OTHER CHANGES FOR COORDINATION WERE ALREADY DONE IN WCNTRL MN. OBS/SATELLITE SHOWS MVFR CIGS ALONG AND EAST OF A WALHALLA TO THIEF RIVER FALLS TO BEMIDJI LINE...WITH SLOW CLEARING TO THE EAST. LATEST RAP MODEL (01Z) INDICATES CLOUDS WILL CONTINUE TO SLOWLY CLEAR FROM THE WEST BUT NOT REACHING LAKE OF THE WOODS AREA TIL ABOUT 09Z. THUS UPDATED SKY COVER WITH THIS TIMING. OTHERWISE CLEAR UNTIL HIGH CLOUDS MOVE LATE TONIGHT AND TUESDAY MORNING. INCOMING 00Z NAM IS A BIT SLOWER WITH PRECIP MOSTLY AN AFTN EVENT IN THE VALLEY INTO NW MN. AMOUNTS STILL LOOK LIGHT. && .PREV DISCUSSION... /ISSUED 553 PM CST MON JAN 7 2013/ DISCUSSION... WFO MPX COORDINATE EARLY UPDATE TO INCREASE POPS IN WCNTRL MN TUESDAY AFTN TO LIKELY. EXPECT A BAND OF LIGHT SNOW TO MOVE THRU BUT AMOUNTS QUITE LOW IN WCNTRL MN...BUT CONFIDENT SOME LIGHT SNOW WILL INDEED FALL. SO TO BLEND WITH MPX UPDATE SPREAD 60 POPS SOUTHEAST INTO WCNTRL MN TUES AFTN. NO OTHER CHANGES. PREV DISCUSSION... /ISSUED 259 PM CST MON JAN 7 2013/ SHORT TERM... CHALLENGES FOR THE FORECAST INCLUDE TEMPS THRU THURSDAY AND AREAL COVERAGE AND AMOUNT OF SNOW WITH PROGRESSIVE SYSTEM ON TUESDAY THEN WINDS IN WAKE OF AFOREMENTIONED SYSTEM TUESDAY AFTN AND EVENING. MODELS IN FAIR AGREEMENT WITH THE SHORT TERM AND USED A BLEND FOR THE PACKAGE. CURRENTLY WARM WESTERLY WINDS AT SFC UNDER A BROAD SHORT WAVE TROUGH GIVING 500MB WESTERLY FLOW AS THE LATEST SHORT WAVE AND ASSOCIATED SFC LOW IN THE PROGRESSIVE WAVE TRAIN HAVE MOVED INTO W ONTARIO. A RELATIVELY TIGHT PRESSURE GRADIENT SHOULD REMAIN AS WINDS TURN FROM THE WEST TO SOUTH WITH THE APPROACH OF THE NEXT SHORT WAVE...KEEPING WINDS FROM COMPLETELY DECOUPLING AND ALLOWING TEMPS TO DROPS DRAMATICALLY OVERNIGHT. TUESDAY WILL SEE SNOW IN THE DVL BSN BY 12Z QUICKLY MOVE EAST AND ACROSS THE N RRV WITH LIKELY POPS AS THE BEST FORCING ALLOWS FOR ONLY AN INCH OR TWO OF ACCUM ALONG AND NORTH OF HWY 200 AS THE SYSTEM REMAINS VERY PROGRESSIVE. TIMING OF THE ARRIVAL OF WESTERLY WINDS AND HOW WELL THEY MIX IN THE VALLEY REMAINS A CONCERN. MODELS INDICATE 50KTS IN THE 00 TO 06Z TIME FRAME ACROSS THE WEST AND RRV AT 925MB. HOWEVER THERE REMAINS LITTLE LOW LEVEL CAA AND LAPSE RATES IN THE LOWEST 500M AT BEST REACH 4 TO 5 C/KM. SO CURRENT THINKING IS THAT IT MAY BE WINDY BUT DON/T SEE REACHING ANY HEADLINE CRITERIA EXCEPT FOR THE HIGHER ELEVATIONS IN THE DVL BSN AND MAYBE SOUTH ALONG THE RIDGE SEPARATING THE JAMES AND SHEYENNE RIVER VALLEYS FOR A BRIEF PERIOD...MAYBE 2 HOURS...BEFORE SUNSET. WINDS TO DIMINISH EARLY WEDNESDAY AS SFC RIDGE AXIS WILL MOVE ACROSS THE CWFA IN THE AM KEEPING TEMPS SLOW TO RISE EVEN UNDER MOSTLY CLEAR SKIES. WITH RETURN FLOW SETTING UP IN THE WEST AS NEXT SFC LOW DEVELOPS IN WESTERN SASKATCHEWAN AND GOOD MIXING CONTINUING OVERNIGHT MAY SEE LITTLE TO STEADY TEMPS WED PM. BY THURS AM S SFC WINDS WITH 925MB TEMPS IN THE PLUS 2 TO 3 RANGE WITH WHAT IS CURRENTLY EXPECTED TO BE FULL SOLAR SHOULD ALLOW TEMPS TO REACH MID 30S ACROSS THE CWFA. LONG TERM (THURSDAY NIGHT-MONDAY)... MEDIUM RANGE MODELS ARE IN FAIRLY GOOD AGREEMENT ON A SIGNIFICANT PATTERN CHANGE FOR THE PERIOD...BUT DIFFER ON THE PARTICULARS. THURSDAY NIGHT THE UPPER LOW OVER THE SOUTHERN PLAINS EARLIER WILL BE EJECTING OUT INTO THE GREAT LAKES...WITH THE MODELS SHOWING DIFFERENT TIMING AND TRACKS OF THIS SYSTEM. OF BETTER AGREEMENT IS A LARGE TROUGH JUST TO OUR WEST...LEAVING THE CWA IN SOUTHWESTERLY FLOW ALOFT. MODELS ALL BRING SOME PRECIP INTO THE SOUTHEASTERN CWA AS THE SOUTHERN SYSTEM MOVES BY. WILL CONTINUE TO KEEP CHANCE POPS OVER THAT AREA WITH LESSER CHANCES FURTHER NORTHWEST AS A FRONTAL BOUNDARY MOVES INTO THE AREA. MODEL SOUNDINGS HAVE A DECENT WARM LAYER ALOFT THURSDAY NIGHT BEFORE THE COLDER AIR MOVES IN FROM THE NORTH. MIXED PRECIP IS NOT OUT OF THE QUESTION...ALTHOUGH THE EXACT TEMPERATURE PROFILE IS STILL VERY UNCERTAIN. WILL INCLUDE A SLEET MENTION ALONG WITH SNOW THURSDAY EVENING FOR NOW BUT SOME FZRA IS POSSIBLE DEPENDING ON JUST HOW WARM THE LAYER ALOFT GETS. PRECIP SHOULD QUICKLY TRANSITION TO ALL SNOW AS THE UPPER TROUGH MOVES EAST AND COLD AIR FUNNELS IN FROM THE NORTH. CONTINUED TO KEEP POPS OVER THE AREA THROUGH FRIDAY AND SATURDAY AS A MID LEVEL DEFORMATION ZONE CONTINUES TO LINGER OVER THE NORTHERN PLAINS. WE SHOULD BEGIN TO DRY OUT FOR SUNDAY AND MONDAY AS COLD HIGH PRESSURE BUILDS IN AND SKIES BEGIN TO CLEAR. TEMPS SHOULD DROP TO VALUES WELL BELOW AVERAGE FOR THE WEEKEND AND INTO MONDAY...WITH HIGHS IN THE SINGLE DIGITS AND LOWS BELOW ZERO. AVIATION... MVFR STRATUS HAS DROPPED FURTHER SOUTH THAN EXPECTED AND IMPACTED KTVF. THINK THAT THE CEILINGS SHOULD SCATTER OUT IN THE NEXT FEW HOURS. WEST WINDS WILL DROP INTO THE 10 TO 15 KT RANGE SHORTLY BEFORE 00Z. THE WINDS WILL GRADUALLY SHIFT AROUND TO THE SOUTH BY MORNING...AND THEN BY TOMORROW AFTERNOON SHIFT TO THE WEST AGAIN AND PICK UP ABOVE 15 KTS. THERE WILL BE A PERIOD OF MVFR TO IFR CEILINGS MOVING FROM WEST TO EAST TOMORROW AND SOME -SN...BUT VISB ARE EXPECTED TO STAY IN THE 2-5SM RANGE AS SNOW MOVES THROUGH. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ RIDDLE/JK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
322 AM CST SUN JAN 6 2013 .SHORT TERM...TODAY THROUGH MONDAY... THE MAIN CHALLENGE FOR THE SHORT TERM IS FOG AND STRATUS THIS MORNING. OTHERWISE...THE BEGINNING OF A PERIOD OF ABOVE AVERAGE TEMPERATURES WILL HIGHLIGHT THE SHORT TERM. THE HRRR SO FAR HAS HAD A GOOD HANDLE ON THE STRATUS THROUGH THE NIGHT THAT HAS SPREAD SOUTHEAST OUT OF SOUTHERN CANADA. EXPECT MOST AREAS ALONG AND EAST OF A LINE FROM CROSBY THROUGH BISMARCK AND LINTON TO BE UNDER THE STRATUS DECK BY 12 UTC. DID MAINTAIN THE MENTION OF PATCHY FOG AND FLURRIES UNDER THIS DECK BASED UPON SURFACE OBSERVATIONAL TRENDS THROUGH THE NIGHT. HOWEVER...THE STRATUS DECK SHOULD QUICKLY BEGIN TO ERODE...ESPECIALLY BETWEEN 15-18 UTC...AS SOUTHWESTERLY WINDS IN THE 925-850 MB LAYER INCREASE. OTHERWISE FOR TODAY...ALL OF WESTERN AND CENTRAL NORTH DAKOTA WILL RESIDE WITHIN THE WARM SECTOR OF A SURFACE LOW ACROSS SOUTHEASTERN SASKATCHEWAN. GIVEN A LOW LEVEL WARM AIR ADVECTION REGIME IN SOUTHERLY FLOW...THE CHALLENGE IS HOW MUCH WARM AIR CAN BE MIXED TO THE SURFACE FROM AN INVERSION THAT WILL BE REINFORCED BY THE SNOWPACK. THE TREND THE PAST COUPLE OF DAYS IN A SIMILIAR SETUP HAS BEEN FOR THE STATISTICAL GUIDANCE TO BE ABOUT 3 TO 5 DEGREES TOO WARM...AND THE DETERMINISTIC MODELS TO ABOUT THE SAME AMOUNT TOO COLD. THUS WILL USE A BLEND OF THE TWO GUIDANCE SUITES WHICH YIELDS HIGHS IN THE LOWER 20S ACROSS THE JAMES RIVER VALLEY WHERE THE LEAST MIXING IS EXPECTED...TO THE LOW TO MID 30S ACROSS THE FAR WEST WHERE WINDS TURN SOUTHWEST AHEAD OF AN ADVANCING COLD FRONT WHICH SHOULD ALLOW FOR GREATER MIXING HEIGHTS TO BE ACHIEVED. THE AFOREMENTIONED COLD FRONT PROPAGATES ACROSS THE AREA DURING THE EVENING AND OVERNIGHT...WITH POST FRONTAL MIXING PREVENTING ANY FOG FORMATION RESULTING FROM SNOW MELT. CANNOT RULE OUT AN ISOLATED SNOW SHOWER ACROSS THE FAR NORTH WITH THE PASSAGE OF THE FRONT CLOSER TO THE STRONGER UPPER LEVEL FORCING. HOWEVER...MOISTURE IS LIMITED AND MAINTAINED A DRY FORECAST FOR TONIGHT. FOR MONDAY...DESPITE BEING IN THE WAKE OF A COLD FRONT...GOOD MIXING FROM WESTERLY WINDS OF 15 TO 20 KTS ARE EXPECTED TO ALLOW TEMPERATURES TO MIX OUT TO VALUES SIMILIAR TO THOSE SEEN ON SUNDAY...AND LIKELY WARMER ACROSS THE SOUTH CENTRAL AND JAMES RIVER VALLEY. WITH A SMALL SPREAD IN FORECAST HIGHS ON THE 00 UTC STATISTICAL AND DETERMINISTIC GUIDANCE...USED A BLEND OF BOTH YIELDING HIGHS FROM THE MID 20S NORTH TO THE LOWER 30S SOUTH. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY... THE MEDIUM RANGE MODEL CONSENSUS PROGS A CLIPPER SYSTEM TO TRAVERSE WESTERN AND CENTRAL NORTH DAKOTA MONDAY NIGHT THROUGH TUESDAY. A WINTRY MIX WILL BE POSSIBLE AROUND THE I-94 CORRIDOR WITH THE PRECIP TYPE EXPECTED TO GENERALLY BE ALL SNOW NORTH OF I-94 TUESDAY. NEW SNOWFALL ACCUMULATIONS ARE EXPECTED TO REMAIN LESS THAN 1 INCH. MAINLY DRY CONDITIONS WITH WELL ABOVE NORMAL TEMPERATURES ARE FORECAST FOR WEDNESDAY. THE GEM/GFS/ECMWF HAVE SLOWED THE PROGRESSION OF A LONG WAVE TROUGH ACROSS THE WESTERN CONUS AND ITS ATTENDANT COLD FRONT INTO NORTH DAKOTA THURSDAY. GIVEN THE SLOWER PROGRESSION...MAINTAINED THE SLIGHT CHANCES FOR PRECIPITATION WEST THURSDAY...THEN BROAD BRUSHED CHANCE/SLIGHT CHANCE POPS ACROSS THE ENTIRE CWA THURSDAY NIGHT. THE SLIGHT CHANCES FOR SNOW SHOULD TAPER OFF FRIDAY. MUCH COLDER AIR IS THEN EXPECTED TO PLUNGE ACROSS THE NORTHERN PLAINS BEHIND THE FRONT. WELL BELOW NORMAL TEMPERATURES ARE EXPECTED FRIDAY AND SATURDAY AS A RESULT. HIGHS ARE GENERALLY EXPECTED TO RANGE FROM THE SINGLE DIGITS TO THE TEENS ABOVE ZERO. LOWS ARE FORECAST TO RANGE FROM THE SINGLE DIGITS BELOW TO SINGLE DIGITS ABOVE ZERO BY THE END OF THE WEEK. && .AVIATION... IFR CIGS IN STRATUS WILL CONTINUE TO DIVE SOUTHEASTWARD ACROSS CENTRAL AND EASTERN NORTH DAKOTA THIS MORNING. KBIS WILL BE ON THE FRINGE OF THIS STRATUS DECK...HENCE THE TEMPO IFR GROUP. HOWEVER...KMOT/KJMS SHOULD REMAIN IFR THROUGH MID-MORNING...THEN BECOME VFR BY LATE MORNING. VFR CONDITIONS ARE THEN EXPECTED FOR WESTERN AND CENTRAL NORTH DAKOTA FROM THIS AFTERNOON THROUGH THE REMAINDER OF THE TAF PERIOD. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...AYD LONG TERM/AVIATION...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1240 AM CST SUN JAN 6 2013 .DISCUSSION... SIGNIFICANT CHANGES TO OVERNIGHT SKY COVER WERE MADE WITH THIS FORECAST UPDATE AS LOW LEVEL STRATUS CONTINUES TO SPREAD SOUTHEAST OUT OF SOUTHERN CANADA. THE LATEST RUNS OF THE HRRR HAVE A GOOD HANDLE ON THIS DECK...AND WILL FOLLOW IT FOR CLOUD COVER THROUGH THE NIGHT...WITH ALL AREAS ALONG AND EAST OF A LINE FROM CROSBY THROUGH BISMARCK AND FORT YATES TO BE UNDER THE DECK BY 12 UTC. BASED UPON THE LATEST SURFACE OBSERVATIONAL TRENDS...PATCHY FOG AND FLURRIES ARE ALSO ASSOCIATED WITH THE STRATUS DECK AND REFLECTED THIS IN THE GRIDS FOR ALL AREAS TO BE IMPACTED BY THE STRATUS. && .AVIATION... A SHIELD OF MAINLY IFR STRATUS WILL CONTINUE TO DROP SOUTH THROUGH THE OVERNIGHT HOURS. LATEST SATELLITE TRENDS AND SHORT RANGE RH PROGS INDICATE ALL TAF SITES EXCEPT KDIK WILL BE IMPACTED...ESPECIALLY KMOT/KBIS/KJMS. SOME PERIODS OF MVFR FOG ARE ALSO POSSIBLE. LOWER CLOUDS WILL SCATTER OUT BY MID TO LATE MORNING AS SOUTHERLY WINDS PICK UP. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AYD AVIATION...RK
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
530 PM CST MON JAN 7 2013 .DISCUSSION.../ISSUED AT 343 PM/ MULTIPLE PLAYERS IN TODAY/S FORECAST FOR TONIGHT INTO TOMORROW. CURRENTLY...MOSTLY CLEAR SKIES ACROSS THE AREA WITH A FEW HIGH CLOUDS ACROSS CENTRAL SOUTH DAKOTA. THE SUNSHINE HAS PROMOTED SNOW MELT...BUT WITH WEAK WINDS AND STRONG INVERSION...MOISTURE REMAINS IN THE NEAR SURFACE LAYER. COULD SEE FOG DEVELOP OVERNIGHT TONIGHT...BUT TRICKY TO PIN POINT WHERE EXACTLY. HRRR CONTINUES TO SUGGEST THAT PATCHY FOG WILL BE POSSIBLY ACROSS THE NORTH...WHILE NAM FOCUSES ON THE SOUTH AND EAST. HAVE SIDED CLOSER TO NAM...BUT WITH WEAK WINDS...COULD GET RADIATIONAL FOG NEARLY ANYWHERE CLEAR SKIES REMAIN FOR A FEW HOURS. AS MENTIONED IN THE MORNING DISCUSSION...AMPLIFYING WAVE MOVING ACROSS THE AREA LATE TONIGHT WITH UPPER LEVEL DIV Q INCREASING AFTER 06Z MAINLY ACROSS THE NORTHERN HALF OF THE FORECAST AREA. WITH FAIRLY DRY AIR THROUGH THE MID LEVELS OF THE ATMOSPHERE...AM NOT EXPECTING ANY PRECIPITATION AND DROPPED MENTION OF SPRINKLES/FLURRIES FROM THE FORECAST. IF FOG DEVELOPS IN THE SOUTHEAST...WILL NEED TO KEEP AN EYE ON DRIZZLE POTENTIAL WITH WEAK LIFT IN THE LOW LEVELS OF THE ATMOSPHERE. COLD FRONT IS POISED TO MOVE THROUGH THE AREA ON TUESDAY. SOUTHERLY WINDS WILL BECOME WEST AND SOMEWHAT GUSTY BEHIND THE FRONT WITH 20-30 KNOTS OF FLOW AT 925 HPA. NOT MUCH IN THE WAY OF COLD AIR ADVECTION BEHIND THE FRONT...AND WITH ONLY MEAGER PRESSURE RISES AND STRONG INVERSION REMAINING ALOFT...WILL STRUGGLE TO GET A LOT OF THE MOMENTUM DOWN THE SURFACE. STRONGEST WINDS WILL LIKELY BE ACROSS THE NORTHERN EDGE OF THE FORECAST AREA WITH STRONGEST GRADIENT WINDS THERE...BUT STILL LOOK TO REMAIN BELOW ADVISORY CRITERIA. UPPER LEVEL TROUGH IS EXPECTED TO DIG ACROSS THE DESERT SOUTHWEST MID WEEK...WHICH PUSHES THE RIDGE AXIS OVER THE FORECAST AREA ON WEDNESDAY. EXPECT ANOTHER RELATIVELY MILD DAY WITH MOSTLY SUNNY SKIES AND ABOVE NORMAL TEMPERATURES. EXPECT HIGHS TO REACH JUST ABOVE FREEZING IN SOUTHWEST MINNESOTA AND ADJACENT AREAS...NUDGING INTO THE UPPER 30S IN NORTHWEST IOWA. THE WARMEST READINGS WILL BE FOUND IN SOUTH CENTRAL SOUTH DAKOTA WITH THE MID OR UPPER 40S IN AREAS WHERE MUCH OF THE SNOWPACK HAS MELTED. FOR THURSDAY...A CUT OFF LOW IS EXPECTED TO FORM IN THE SOUTHWEST PLAINS AND TRACK NORTHEAST INTO THE NORTHERN GREAT LAKES EARLY SATURDAY. SOME MODEL DIFFERENCES STILL EXIST...WITH THE ECMWF AND GEM STILL FOLLOWING A SLOWER AND SLIGHTLY MORE SOUTHERLY TRACK. ALL MODELS DO CLIP OUR SOUTHEASTERN COUNTIES AS THE SURFACE LOW TRACKS INTO IOWA THURSDAY EVENING. TEMPERATURES WILL BE PARTICULARLY TRICKY WITH READINGS EXPECTED TO RISE UP ABOVE FREEZING BY THE AFTERNOON. WITH VERY WARM LOW LEVELS...EXPECT PRECIPITATION TO BE ENTIRELY LIQUID FOR THIS SYSTEM...BUT WITH SURFACE READINGS POTENTIALLY BELOW FREEZING IN THE MORNING AND AGAIN THURSDAY NIGHT...FREEZING RAIN WILL ALSO BE POSSIBLE. BUT GIVEN THAT THESE TEMPERATURES WILL ONLY BE A DEGREE OR TWO BELOW FREEZING...ICE ACCUMULATION DOES NOT LOOK TO BE SIGNIFICANT. BUT WILL STILL CONTINUE TO MONITOR FOR ANY CHANGES IN THIS OUTLOOK. TEMPERATURES ON FRIDAY WILL LIKELY BE SOMEWHAT STEADY OR BEGIN TO FALL IN THE AFTERNOON AS COOLER TEMPERATURES BEGIN TO FILTER INTO THE AREA BEHIND THIS SYSTEM. THE BROAD POSITIVELY TILTED TROUGH DIGGING ACROSS THE SOUTHWEST PUSHES INTO THE WESTERN PLAINS FRIDAY EVENING...BRINGING THE NEXT POTENTIAL FOR WET WEATHER TO REGION FRIDAY NIGHT AND SATURDAY. AGAIN...THE ECMWF IS A BIT SLOWER AND SHOWS MORE OF A CLOSED UPPER LEVEL FEATURE. A SLIGHT CHANCE FOR SOME LIGHT SNOW OR FLURRIES WILL BE POSSIBLE AHEAD OF THE MAIN WAVE ON FRIDAY. THE DETAILS ARE STILL QUITE UNCERTAIN AT THIS POINT...BUT THE GFS APPEARS TO TAKE THE BEST DYNAMICS WEST AND NORTH OF THE FORECAST AREA...WHILE THE ECMWF HAS A BIT MORE ORGANIZATION WITH A DECENT BAND OF MID LEVEL FRONTOGENESIS MOVING THROUGH THE FORECAST AREA. WILL KEEP MENTION OF POPS AS A HIGH CHANCE FOR SOME LIGHT SNOWFALL FRIDAY NIGHT AND SATURDAY. PRELIMINARY AMOUNTS LOOK LIKE A FEW INCHES WOULD BE POSSIBLE ACROSS THE CWA. THE LOW EXITS THE AREA SATURDAY NIGHT WITH A STRONGER SHOT OF COLD AIR ADVECTION ARRIVING IN ITS WAKE. TEMPERATURES WILL BE MUCH COOLER FOR THE START OF NEXT WEEK WITH HIGHS MAINLY IN THE TEENS AND LOWS AROUND ZERO. && .AVIATION.../FOR THE 00Z TAF ISSUANCE/ CRITICAL ISSUE FOR THE NIGHT WOULD BE POTENTIAL FOR IFR CEILING AND VISIBILITY DEVELOPMENT AFTER A DAY OF MELTING...WITH WEAK HIGH PRESSURE SLOWLY PUSHING EAST ACROSS THE AREA. AFTER PERUSING THE VARIOUS LOWER LEVEL THERMAL PROFILES...SEEMS MORE LIKELY TO BE A SITUATION WHERE WILL FROST OUT A GOOD DEAL OF THE SUB INVERSION MOISTURE WITH TEMP/DEWPOINT PROFILES CRASHING IN TANDEM...RATHER THAN A MORE WIDESPREAD FOG DEVELOPMENT. WILL LIKELY DEAL WITH A LONGER PERIOD OF BORDERLINE MVFR VISIBILITIES WITH STRONG INVERSION LINGERING ALL THE WAY THROUGH THE MORNING...AND PERHAPS EVEN UNTIL WIND SHIFT IN THE AFTERNOON FOR KFSD AND KSUX. RETAINED A FEW-SCATTERED MENTION FOR LOWER CEILINGS...BUT THINK MORE PROBABLE EVENT WOULD BE MVFR VISIBILITIES...AND HAVE PLACED THOSE CONDITIONS IN PREVAILING. WINDS WILL INCREASE BEHIND BOUNDARY...AND MODELS APPEAR TO HANG ON TO TOO COOL SURFACE LAYER TEMPS AND DO NOT ALLOW FOR THE BETTER MIXING THAT PROGGED SURFACE READINGS WOULD ALLOW... SO PUT IN SOME WIND GUSTS DURING THE AFTERNOON EXCEEDING 25 KNOTS AROUND KHON...AND CLOSE TO THRESHOLD FOR KFSD/KSUX A BIT LATER INTO THE AFTERNOON. /CHAPMAN && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1054 PM CST SAT JAN 5 2013 .DISCUSSION.../ISSUED AT 930 PM CST/ LOW CLOUDS ARE CLEARING VERY STRONGLY. LINGERING BAND OF LOW LEVEL MOISTURE WEST WAITING FOR WARM ADVECTION TO START LOOKS TOO WEAK WITH CLOUDS THERE RAPIDLY DISSIPATING...AND GIVEN NEW NAM RH FIELDS...REDEVELOPMENT NOT EXPECTED. SKIES SHOULD GO CLEAR TO MOSTLY CLEAR TONIGHT. FOR THIS HAVE ALLOWED TEMPERATURES A LITTLE BETTER LATE DROP AS WINDS CONTINUE TO DECREASE WITH LOWS 2 TO 4 DEGREES LOWER THAN BEFORE. WHILE SOME WARM ADVECTION UPSTAIRS WILL START SOON...SURFACE SHOULD BE IGNORED ON THIS TONIGHT. LOW TEMPS IN THE SINGLE DIGITS EVERYWHERE AND MAYBE A ZERO HERE AND THERE. && .AVIATION.../FOR THE 06Z TAF ISSUANCE/ MVFR STRATUS SHOULD EXIT FAR SOUTHERN PORTIONS OF THE FORECAST AREA EARLY IN THE PERIOD...07Z-08Z...TAKING ANY FLURRIES ALONG WITH IT. RELATIVELY NARROW BAND OF LOW MVFR-IFR STRATUS DRIFTING SOUTHEAST THROUGH NORTHEAST/EAST CENTRAL SD AND FAR WESTERN MN AT THE START OF THE PERIOD WILL SLIDE MAINLY EAST OF I-29 CORRIDOR...DRIFTING ACROSS SOUTHWEST MN/NORTHWEST IA THROUGH EARLY SUNDAY MORNING. COULD SCRAPE CLOSE ENOUGH TO KFSD TO GIVE BRIEF PERIOD OF MVFR-IFR CEILINGS 07Z TO 09Z WINDOW...BUT CONFIDENCE IN WESTWARD EXTENT IS LOW...SO WILL KEEP TAF IN VFR RANGE. LINGERING NORTHWESTERLY WIND GUSTS 20-25KTS OVER SOUTHEAST HALF OF THE FORECAST AREA WILL CONTINUE TO SLOWLY SUBSIDE THROUGH THE OVERNIGHT HOURS...WITH LIGHT/VARIABLE WINDS BECOMING SOUTH MOST AREAS BY SUNDAY AFTERNOON. INCREASING SOUTHERLY FLOW EXPECTED TO SPREAD ACROSS THE AREA LATE SUNDAY AFTERNOON AND EVENING...WITH GUSTS 20-25KTS LIKELY WEST OF JAMES RIVER VALLEY LATE SUNDAY AFTERNOON...AND OVER MUCH OF SOUTHEAST SD/SOUTHWEST MN SUNDAY EVENING. && .PREV DISCUSSION.../ISSUED AT 342 PM CST/ UPPER WAVE PUSHING ACROSS THE DAKOTAS THIS AFTERNOON...DRIVING COLD FRONT INTO THE FAR EASTERN PORTIONS OF THE STATE AT MID AFTERNOON. CLOUDS PUSHING IN WITH STRONG COLD AIR ADVECTION...AND WITH OFF SURFACE TEMPS FALLING QUICKLY TOWARD THOSE FAVORING ICE NUCLEATION... HAVE SEEN FLURRIES DROP IN TO PARTS OF EAST CENTRAL SOUTH DAKOTA. THE CLOUDS AND FLURRIES WILL CONTINUE TO PUSH EAST AND SOUTHEAST THIS EVENING...BUT IT IS CERTAINLY A CHALLENGE AS TO HOW QUICKLY TO BRING IN A MORE PERMANENT CLEARING. RAP AND 18Z NAM ARE NOW IN FAVOR OF HANGING BACK A PERIOD OF LOWER CLOUDS LATER INTO THE NIGHT NEAR/WEST OF THE JAMES RIVER AND THEN DRIFTING EAST AS FLOW ALOFT STARTS TO TURN A BIT MORE WESTERLY. THIS ALSO PRESENTS A LARGE CHALLENGE TO TEMPERATURES...WHICH WILL PROVE ALMOST IMPOSSIBLE TO GET CLOSE ON AN HOURLY TIME FRAME WITH IN AND OUT CLOUD TRENDS. EXPECT A BETTER PUSH OF CLEARING THROUGH THE EASTERN CWA BY LATER EVENING...BUT ENOUGH WIND OR A FEW MORE CLOUDS LIKELY TO KEEP TEMPS FROM PLUNGING TOO FAR ANYWHERE. GENERALLY LOOKING FOR QUITE A FEW SINGLE DIGITS...WITH READINGS AROUND 10 WEST AS WARMER AIR SHUNTS EAST FAIRLY QUICKLY. SUNDAY AGAIN PRESENTS A SMALL CHALLENGE TO TEMPS...WITH A VERY WEAK GRADIENT THROUGH MIDDAY OR EVEN EARLY AFTERNOON IN THE FAR SOUTHEAST. LOWER ELEVATION LOCATIONS COULD EASILY ONCE AGAIN FIND THEMSELVES MIRED IN CHILLIER AIR...WITH THE INCREASING SOUTHERLY GRADIENT MAINLY ACROSS SOUTHEAST SOUTH DAKOTA AND INTO SOUTHWEST MINNESOTA DURING THE AFTERNOON. HIGH CLOUDS PUSHING ACROSS WOULD ONLY ENHANCE THE POTENTIAL FOR THIS TO OCCUR...SO WAS CAREFUL TO NOT WARM CONDITIONS IN THE EAST TOO MUCH...AND DID NUDGE SOME TEMPERATURES DOWN ACROSS PARTS OF NW IA. THE WEST WILL BE OPEN TO SOME BETTER WARMING...BUT EVEN THERE THE INVERSION WILL PRESENT A BIT OF A CHALLENGE TO LOWER ELEVATION WARMING. /CHAPMAN THE PATTERN OF MILD WEATHER WILL CONTINUE THROUGH MUCH OF THE WEEK AS A MORE ZONAL PATTERN SETS UP FOR THE FIRST HALF OF THE WORK WEEK. MILDER WEST TO SOUTHWEST FLOW WILL MAKE TEMPERATURES QUITE TRICKY TO PINPOINT...PARTICULARLY REGARDING OVERNIGHT LOWS. FOR SUNDAY NIGHT...BREEZY SOUTH TO SOUTHWEST WINDS WILL LIKELY RESULT IN A NON-DIURNAL TEMPERATURE TREND WITH LOWS EXPECTED IN THE EVENING OR SHORTLY AFTER MIDNIGHT...THEN SLOWLY RISING LATE. THE QUESTION IS HOW COOL WE WILL BE ABLE TO FALL OFF IN THE EVENING. OTHERWISE... HIGH TEMPERATURES FOR TUESDAY AND WEDNESDAY WILL LIKELY BE NEAR OR JUST ABOVE FREEZING...WITH THE HIGHS IN THE LOW 40S POSSIBLE IN SOUTH CENTRAL SD WHERE THE GREATEST POTENTIAL MIXING OF THE MILD LOW LEVEL TEMPERATURES COULD OCCUR. LATEST MODEL RUNS SHOWING A LITTLE BETTER AGREEMENT FOR THE SYSTEM ON WEDNESDAY NIGHT AND THURSDAY...BUT DIVERGE A BIT LEADING INTO NEXT WEEKEND. ALSO OF NOTE ARE SOME PRETTY BIG CHANGES FROM EARLIER MODELS RUNS. LATEST 12Z RUNS OF GFS AND ECMWF ARE MUCH SLOWER AND FURTHER SOUTH WITH THE CLOSED LOW SYSTEM...RESULTING IN LITTLE TO NO IMPACT ACROSS OUR FORECAST AREA. WENT AHEAD AND REMOVED MENTION OF POPS FOR WEDNESDAY GIVEN THE SLOWER TIMING. DECIDED TO KEEP MENTION OF LOW CHANCE POPS MAINLY IN NORTHWEST IOWA ON THURSDAY GIVEN THE RECENT INCONSISTENCIES BETWEEN MODEL RUNS...BUT DID TRIM BACK COVERAGE AND QUITE A BIT FROM THE ALL BLEND...WHICH WAS BIASED FROM THE 00Z ECMWF RUN. TEMPERATURES REMAIN QUITE MILD INTO THURSDAY... BRINGING THE QUESTION OF PRECIPITATION TYPE IF THIS SYSTEM DOES GRAZE OUR SOUTHEAST CWA. GIVEN WHAT LOOKS LIKE VERY MILD LOW/MID LEVELS...PRECIPITATION TYPE MAY BECOME A CONCERN EARLY THURSDAY... BUT WITH MANY FACTORS UP IN THE AIR...WILL KEEP IT SIMPLE WITH A RAIN AND SNOW MIX. THE NEXT AREA OF UNCERTAINTY IS REGARDING A STORM SYSTEM AROUND THE SATURDAY TIME FRAME. MODELS CONTINUE TO FLIP FLOP WITH SOLUTIONS...RESULTING IN LARGE TEMPERATURE AND POP DIFFERENCES. NOT A WHOLE LOT OF CONFIDENCE...ESPECIALLY WITH THE VERY EXTREME GFS SOLUTION. IT DOES LOOK LIKE A BIT OF A COOL DOWN FRIDAY AND SATURDAY COMPARED TO EARLIER IN THE WEEK...BUT NOTHING TOO EXTREME. DID NOT ALTER MUCH FROM THE ALLBLEND. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1138 PM CST SAT JAN 5 2013 .SHORT TERM...TONIGHT 645 PM CST SAT JAN 5 2013 HAVE MADE SOME UPDATES TO THE FORECAST THIS EVENING WITH THE PROSPECTS FOR DRIZZLE/FREEZING DRIZZLE. FIRST...TEMPERATURES HAVE REMAINED ABOVE FREEZING IN THE WARM SECTOR AHEAD OF THE COLD FRONT THAT CURRENTLY RUNS THROUGH NORTHEAST IOWA UP TO A TRIPLE POINT IN WESTERN WISCONSIN WITH A WARM FRONT EXTENDING EAST ACROSS WISCONSIN TOWARD GREEN BAY. CEILINGS FROM NORTHEAST IOWA INTO SOUTHWEST WISCONSIN HAVE NOT BEEN AS LOW AS YOU WOULD WANT FOR DRIZZLE TO OCCUR WITH THEM BEING AT 2-4KFT. OBSERVATIONS FROM DOWN IN THIS REGION ALL SHOW VISIBILITY UP AT GREATER THAN 6SM WITH NO REPORTS OF DRIZZLE THIS AFTERNOON/EARLY EVENING. 05.22Z RAP SOUNDINGS OUT OF DBQ SEEM TO PAINT THE PICTURE WELL WITH A SATURATED...PROBABLY OVERLY SATURATED...LOW LEVEL WITH NO VERTICAL MOTIONS. BASED ON THESE FACTORS...HAVE REMOVED THE FREEZING DRIZZLE/DRIZZLE MENTION FOR THIS EVENING. THE SECOND WAVE THEN COMES IN AS A SECONDARY COLD FRONT WHICH CURRENTLY IS DROPPING SOUTH ON THE BACK SIDE OF THE SURFACE LOW ACROSS SOUTHERN MINNESOTA. THERE IS A BRIEF PERIOD OF CLEARING...BUT THEN THERE IS A PATCH OF LOW LEVEL CLOUD COVER TRACKING TO THE SOUTHEAST FROM SOUTH DAKOTA INTO CENTRAL IOWA. MODELS HAVE BEEN OVER-DOING THE LOW LEVEL MOISTURE WITH THIS FEATURE AND SHOW THAT WE SHOULD BE COMPLETELY OVERCAST AT THIS POINT. HAVE LEFT SKY CONDITIONS AS MOSTLY CLOUDY TO CLOUDY TONIGHT...BUT THAT MAY BE ON THE PESSIMISTIC SIDE GIVEN CURRENT UPSTREAM CONDITIONS. 05.22Z RAP SOUNDINGS DO SHOW THAT IF THE LOW LEVEL DECK DOES OCCUR THAT IT SHOULD BECOME COLDER THAN -8C THAT ICE WOULD BE INTRODUCED. WITH WEAK FORCING...SHOULD SEE SOME FLURRIES/SNOW SHOWERS WITH IT. THE LOW VISIBILITIES CURRENTLY OCCURRING IN WEST CENTRAL MINNESOTA ARE FROM SNOW SHOWERS THOUGH THEY ARE NOT SHOWING UP ON RADAR BECAUSE THE CLOUD DECK IS JUST A FEW HUNDRED FEET OFF THE GROUND AND BELOW THE RADAR BEAM. THIS AREA APPEARS TO BE RUNNING SOUTH OF THE FORECAST AREA...BUT WILL HAVE TO MONITOR IT FOR WHETHER SOME SMALL ACCUMULATIONS NEED TO BE ADDED OVERNIGHT. .LONG TERM...TUESDAY THROUGH SATURDAY 201 PM CST SAT JAN 5 2013 MEDIUM RANGE MODELS HAVE STARTED TO COME INTO BETTER AGREEMENT WITH THE SYSTEM EXPECTED TO IMPACT THE GREAT LAKES FOR THE LATTER HALF OF THE WEEK. THE 05.00Z ECMWF HAS REMAINED CONSISTENT WITH ITS PREVIOUS RUNS ON THE TRACK OF THE SYSTEM WHILE THE 05.12Z GFS HAS SHIFTED CONSIDERABLY TOWARD THE ECMWF SOLUTION. THE MODELS ARE NOW VERY SIMILAR IN TIMING BUT THE GFS STILL DOES NOT BRING THE SYSTEM AS FAR NORTH AS THE ECMWF. BY 11.00Z /FRIDAY EVENING/ THE ECMWF PLACES THE UPPER LEVEL LOW NEAR THE WISCONSIN-ILLINOIS BORDER BETWEEN KDBQ AND KRST WHILE THE GFS IS FARTHER SOUTH NEAR KSTL. THE AGREEMENT THAT WAS IN PLACE HAS BEEN THROWN OUT THE WINDOW BY THE 05.12Z ECMWF HAS IT HAS COME IN SLOWER AND FARTHER SOUTH AND IS NOT SIMILAR WITH ITS TRACK TO THE GFS. WITH THE DISPARITY BETWEEN THE MODELS...THE ONLY CHANGE MADE TO THE MODEL CONSENSUS GRIDS WAS TO WEDNESDAY NIGHT. WITH THE ECMWF NOW BEING SLOWER...IT SUGGESTS THE PRECIPITATION WILL NOT MOVE IN UNTIL THURSDAY...SO WILL NOW GO WITH A DRY WEDNESDAY NIGHT. THE PRECIPITATION FROM THIS SYSTEM SHOULD START TO MOVE OUT THURSDAY NIGHT OR FRIDAY BUT WILL QUICKLY BE FOLLOWED BY THE NEXT SYSTEM. THE MODELS MAINTAIN A SOUTHWEST FLOW ALOFT BEHIND THIS SYSTEM AND QUICKLY EJECT OUT ANOTHER SYSTEM FROM THE SOUTHERN ROCKIES. THE ECMWF IS QUICKER AND FARTHER NORTH THAN THE GFS IN THE UPPER LEVELS...BUT THE SURFACE TRACKS LOOK TO BE SIMILAR GOING FROM NEAR KMCI TOWARD KMKE EITHER SATURDAY OR SATURDAY NIGHT. THE ECMWF SUGGESTS THE FIRST SYSTEM WILL BRING ENOUGH WARM AIR NORTH TO PRODUCE PRIMARILY RAIN OR A RAIN/SNOW MIX. HOWEVER...THE BAROCLINIC ZONE LEFT BEHIND MAY BE JUST TO THE SOUTHEAST GIVING THE SECOND SYSTEM ENOUGH COLD AIR TO WORK WITH TO PRODUCE MAINLY SNOW. && .AVIATION...THROUGH 06Z MONDAY 1138 PM CST SAT JAN 5 2013 CONFIDENCE IS NOT HIGH WITH THE SKY CONDITIONS OVERNIGHT AS THE LOW LEVEL CLOUD DECK HAS NOT FILLED IN AS ANTICIPATED ACROSS THE REGION. HOWEVER...ANOTHER ROUND OF MVFR 1-2.5KFT STRATUS APPEARS TO BE DROPPING SOUTH OF OUT NORTHWEST WISCONSIN AND NORTHEAST MINNESOTA PER THE LATEST IR SATELLITE IMAGERY/SURFACE OBSERVATIONS. WILL CARRY SOME LOWER CEILINGS THROUGH THE OVERNIGHT HOURS TO ACCOUNT FOR THIS WHICH SHOULD HOLD ON INTO THE MORNING HOURS AND POSSIBLY INTO THE EARLY AFTERNOON. CAN NOT RULE OUT A FEW FLURRIES AS THIS CLOUD DECK MOVES IN...BUT THEY SHOULD NOT BE STRONG ENOUGH TO DROP VISIBILITY DOWN BELOW 6SM. SKIES SHOULD CLEAR INTO THE AFTERNOON ON SUNDAY AS THE SYSTEM PULLS OFF TO THE EAST AND DRIER AIR MOVES IN BEHIND IT. && .ARX WATCHES/WARNINGS/ADVISORIES... 201 PM CST SAT JAN 5 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH LONG TERM...04 AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
336 AM CST Tue Jan 8 2013 .DISCUSSION... In the short term, concerns are focused on temperatures along with rainfall potential Wednesday night into Thursday. Early this morning, a large upper level low continued to spin over northern Mexico as a progressive upper trough crosses the Northern Plains. Due to an enhanced area of cirrus moving across the region, temperatures have remained in the 30s in most locations. Today: Upper troughing in the Northern Plains will establish weak surface troughing across portions of east central Kansas through northwestern Missouri. Winds ahead of this surface trough will again become breezy by afternoon, with abnormally warm 950:850 temperatures supporting temperatures into the 50s in many areas. Again, have followed short term RAP guidance for temperatures this afternoon which did an excellent job on Monday. The warmest temperatures may pool just ahead of this surface trough where readings could spike into the middle 50s. Tonight: The weak surface trough will move into the region washing out as it does so. A bit less cirrus may be possible given the northwesterly upper level flow. The resultant temperatures will fall into the upper 20s in most locations. Wednesday: The upper level low over northern Mexico will finally become dislodged as troughing enters the Pacific Northwest. Locally, an elongated west to east ridge of high pressure will remain over the area throughout the daytime hours, keeping winds light and variable. Temperatures, given the weak boundary and low level flow, will not be quite as warm as on Tuesday but should still climb near 50. Wednesday night: The upper level low will quickly begin to surge north by Wednesday evening with strong low-level moisture advection headed into the area. Showers and even embedded thunderstorms will overspread the area through the overnight hours. Models in reasonable agreement (less the NAM) that rain will reach the Interstate 70 corridor by midnight and northern Missouri by daybreak. Thursday: Tricky forecast as models indicate the deep upper low will lift across the CWA during the daytime hours. Rain should quickly lift northward in the morning, replaced with low cloud cover and periods of showers/drizzle. Temperatures will be rather difficult and highly dependent on the track of surface low pressure and surge of warm air ahead of the surface low. Model guidance suggests a weak surface low tracking north along with the upper low through eastern Kansas by Thursday afternoon. NAM is the most aggressive bringing near 60 degree readings into the CWA, but it is also the deepest and most progressive solution of all guidance. Prefer the weaker solutions of the GFS/SREF which still bring low 50s by the late afternoon hours. Dux Medium Range (Friday through Monday)... The medium range should start out very warm especially for the climatologically coldest week of the year for Kansas City (January 10-17). With 850mb temps between 12C-14C, if we can mix out enough, temperatures could easily range into the mid 50s to mid 60s. However, those warm temperatures will be short-lived as a cold front is forced into the forecast area Friday night in association with a broad and deep upper level trough that will be traversing the Rockies. This frontal passage looks to be dry as models are in good agreement that the best moisture transport is south and east of the forecast area. As such have lowered chance POPs inherited by the initialization to silent slight chance POPs for Saturday. The main effect of this cold front will be the marked change in temperatures. High temperatures across the CWA Saturday will experience a 20 degree range from near 30 across northern Missouri where cold air advection will be ongoing by day break...to near 50 across central Missouri where cold air doesn`t begin to advect in until later in the day. The upper level trough moves through the area on Sunday as high pressure builds in at the surface with highs in the mid 20s to lower 30s. Surface high pressure strengths over the area on Monday and with abundant sunshine highs will return to near normal for the coldest climatological week of the year with highs in the 30s. 73 && .AVIATION... No changes for the 06Z TAFs. Other than periods of broken cirrus, TAFs will feature rather benign conditions over the next 24 hours. Winds will remain 8-10 knots at MCI, but should decouple at MKC/STJ. With the eastern edge of a modest nocturnal jet brushing across STJ overnight, significant low level turning (40-50 degrees) and speed shear (30-35 knots) has resulted in the introduction of LLWS for STJ from midnight through late morning when sufficient mixing depth will eliminate the abrupt inversion. Surface winds should increase to 10-14 knots with a gradual veering toward the southwest during the day, and then toward the west-southwest during the evening. Bookbinder && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1108 PM CST MON JAN 7 2013 .AVIATION... 06Z TAFS FOR KOMA...KLNK...KOFK. FOG HAD DEVELOPED OVER PARTS OF THE AREA...MAINLY WHERE THERE WAS MELTING DURING THE DAY AND SIGNIFICANT SNOW COVER REMAINED IN PLACE. DID MAKE SOME ADJUSTMENTS TO THE TAFS FOR THE OVERNIGHT HOURS AND INTO TUESDAY MORNING. SOME IFR VISIBILITIES WILL BE POSSIBLE...ESPECIALLY FROM BETWEEN 09Z AND 14Z. WILL CONTINUE TO MONITOR FOR DENSE FOG DEVELOPMENT AND AMEND AS NEEDED. LIGHT WINDS TONIGHT WILL BECOME SOUTHERLY TUESDAY MORNING THEN SHIFT TO WEST OR SOUTHWEST IN THE AFTERNOON. MILLER && .PREV DISCUSSION... /ISSUED 1013 PM CST MON JAN 7 2013/ UPDATE... PUBLIC FORECASTS WERE AMENDED TO INCLUDE SOME MENTION OF DENSE FOG OVER AREAS THAT HAVE SNOW COVER. ALSO DECREASED LOWS A BIT IN SOME LOCATIONS. MILLER && PREV DISCUSSION... /ISSUED 234 PM CST MON JAN 7 2013/ SHORT TERM...TONIGHT THROUGH THURSDAY. MAIN FORECAST CONCERNS WILL DEAL WITH TEMPERATURES AND TIMING OF SYSTEM MOVING OUT OF THE SOUTHERN PLAINS WEDNESDAY NIGHT INTO THURSDAY. DESPITE THICK CIRRUS LAYER ACROSS PARTS OF THE AREA AND LIGHT SURFACE WINDS ALONG A WEAK TROUGH INTO EAST CENTRAL NEBRASKA... TEMPERATURES HAVE MANAGED TO CLIMB INTO THE MID AND UPPER 30S IN SNOW COVERED PORTION OF THE CWA WITH MID 40S TO LOWER 50S IN SNOW FREE PARTS OF SOUTHEAST NEBRASKA AND SOUTHWEST IOWA THIS AFTERNOON. INITIAL CONCERN FOR TONIGHT WILL BE POTENTIAL FOG DEVELOPMENT IN THE SNOW AREAS WHERE SOME MELTING TODAY HAS ADDED MOISTURE TO THE BOUNDARY LAYER. SHORT RANGE RAP HINTS AT DEVELOPMENT AFTER 06Z IN AREA WHERE MENTION OF PATCHY FOG IS ALREADY IN CURRENT FORECAST. FOR TUESDAY AND WEDNESDAY QUESTION WILL BE HOW WARM WILL TEMPERATURES BE ABLE TO REACH. BASED ON TODAYS READINGS CLIMBING TO AROUND 50 IN THE SOUTHEAST PART OF THE CWA...HAVE WENT A WARMER THAN GUIDANCE IN THE SNOW FREE AREAS WITH SNOW FIELD STILL EXPECTED TO KEEP TEMPERATURES TO THE NORTH CLOSE TO GUIDANCE. TIMING ISSUES AMONG THE MODELS STILL IN PLAY FOR WEDNESDAY NIGHT AND THURSDAY WITH NAM THE FASTEST AND LEAST REGARDED AT THIS TIME FRAME. GFS AND EURO HAVE BETTER AGREEMENT BUT EURO REMAINS SLOWER IN MOVING THE SYSTEM ACROSS THE AREA. FORECAST SOUNDINGS FOR WEDNESDAY NIGHT SUGGEST TEMPERATURES SHOULD BE WARM ENOUGH ACROSS THE SOUTH HALF OF THE AREA FOR PRECIP TO BE ALL LIQUID WITH TEMPERATURES REMAINING ABOVE FREEZING ON THURSDAY ACROSS ALL THE AREA AS RAIN CONTINUES. FOBERT LONG TERM...THURSDAY NIGHT THROUGH MONDAY. THE GFS AND ECM ARE IN RELATIVELY GOOD AGREEMENT WITH REGARDS TO LARGE SCALE IN THE EXTENDED PD. BOTH ALSO SUGGESTING LITTLE CHANGE NEEDED TO GOING FCST. HEADING INTO NEXT WEEKEND...MODELS ADVERTISE SHORTWAVE ENERGY OVER IA QUICKLY LIFTING TO THE GREAT LAKES REGION LATE THURSDAY NIGHT. MEANWHILE UPSTREAM...A DEEP LONGWAVE TROF IS PROGGED TO EXTEND FROM CNTRL CANADA ALL THE WAY TO THE SWRN CONUS. ON FRIDAY AS THE WRN TROF GRADUALLY MIGRATES EAST...INTENSE BAROCLINIC ZONE BEGINS SWEEPING ACROSS THE NRN/CNTRL PLAINS WITH THE LEADING EDGE OF THE BOUNDARY REACHING THE CWA BY EARLY AFTN. COMBINATION OF INCREASING MOISTURE AND STOUT AGEOSTROPHIC LIFT ALONG DEEP FRONTOGENETIC LYR SHOULD BE ENOUGH TO INDUCE LIGHT SNOW ACTIVITY DURING THE FROPA FRIDAY NIGHT. ON SATURDAY...APPEARS TO BE A SMALL CHANCE FOR LIGHT POST-FRONTAL SNOW ACTIVITY PER THE ECM. 300-500MB QVEC CONVERGENCE IMPLYING LIFT VIA DPVA WHEN POTENT OR MAX ROUNDS THE BASE OF THE WRN TROF AND LIFTS ACROSS THE CNTRL PLAINS. ON THE OTHER HAND...GFS AND CMC BOTH SUGGESTING THE DEEP CAA WILL BE ADEQUATE TO SUPPRESS ANY LIFT VIA DPVA. WILL OPTED FOR TOKEN 20S JUST IN CASE ECM SOLUTION WOULD VERIFY. OTHERWISE...TEMPS WILL PLUMMET OVER THE PLAINS NEXT WEEKEND INTO EARLY NEXT WEEK. EXPECT HIGHS SAT-MON WILL STRUGGLE TO REACH THE LOWER/MID 20S. DEE && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS OMAHA/VALLEY NE
1013 PM CST MON JAN 7 2013 .UPDATE... PUBLIC FORECASTS WERE AMMENDED TO INCLUDE SOME MENTION OF DENSE FOG OVER AREAS THAT HAVE SNOW COVER. ALSO DECREASED LOWS A BIT IN SOME LOCATIONS. MILLER && .PREV DISCUSSION... /ISSUED 522 PM CST MON JAN 7 2013/ AVIATION... 00Z TAFS FOR KOMA...KLNK...KOFK. WILL HAVE TO MONITOR FOR DEVELOPMENT OF STRATUS AND FOG TONIGHT. DID MENTION SOME MVFR VISIBILITIES LATER TONIGHT BUT DID NOT WANT TO GET TOO PESSIMISTIC. GFS MODEL DOES NOT DEVELOP FOG...WHILE THE NAM DOES. GENERALLY FELT THE NAM LOW LEVEL MOISTURE WAS OVERDONE BUT WILL MONITOR AND AMEND TAFS THROUGH THE EVENING AS NEEDED. MILLER PREV DISCUSSION... /ISSUED 234 PM CST MON JAN 7 2013/ SHORT TERM...TONIGHT THROUGH THURSDAY. MAIN FORECAST CONCERNS WILL DEAL WITH TEMPERATURES AND TIMING OF SYSTEM MOVING OUT OF THE SOUTHERN PLAINS WEDNESDAY NIGHT INTO THURSDAY. DESPITE THICK CIRRUS LAYER ACROSS PARTS OF THE AREA AND LIGHT SURFACE WINDS ALONG A WEAK TROUGH INTO EAST CENTRAL NEBRASKA... TEMPERATURES HAVE MANAGED TO CLIMB INTO THE MID AND UPPER 30S IN SNOW COVERED PORTION OF THE CWA WITH MID 40S TO LOWER 50S IN SNOW FREE PARTS OF SOUTHEAST NEBRASKA AND SOUTHWEST IOWA THIS AFTERNOON. INITIAL CONCERN FOR TONIGHT WILL BE POTENTIAL FOG DEVELOPMENT IN THE SNOW AREAS WHERE SOME MELTING TODAY HAS ADDED MOISTURE TO THE BOUNDARY LAYER. SHORT RANGE RAP HINTS AT DEVELOPMENT AFTER 06Z IN AREA WHERE MENTION OF PATCHY FOG IS ALREADY IN CURRENT FORECAST. FOR TUESDAY AND WEDNESDAY QUESTION WILL BE HOW WARM WILL TEMPERATURES BE ABLE TO REACH. BASED ON TODAYS READINGS CLIMBING TO AROUND 50 IN THE SOUTHEAST PART OF THE CWA...HAVE WENT A WARMER THAN GUIDANCE IN THE SNOW FREE AREAS WITH SNOW FIELD STILL EXPECTED TO KEEP TEMPERATURES TO THE NORTH CLOSE TO GUIDANCE. TIMING ISSUES AMONG THE MODELS STILL IN PLAY FOR WEDNESDAY NIGHT AND THURSDAY WITH NAM THE FASTEST AND LEAST REGARDED AT THIS TIME FRAME. GFS AND EURO HAVE BETTER AGREEMENT BUT EURO REMAINS SLOWER IN MOVING THE SYSTEM ACROSS THE AREA. FORECAST SOUNDINGS FOR WEDNESDAY NIGHT SUGGEST TEMPERATURES SHOULD BE WARM ENOUGH ACROSS THE SOUTH HALF OF THE AREA FOR PRECIP TO BE ALL LIQUID WITH TEMPERATURES REMAINING ABOVE FREEZING ON THURSDAY ACROSS ALL THE AREA AS RAIN CONTINUES. FOBERT LONG TERM...THURSDAY NIGHT THROUGH MONDAY. THE GFS AND ECM ARE IN RELATIVELY GOOD AGREEMENT WITH REGARDS TO LARGE SCALE IN THE EXTENDED PD. BOTH ALSO SUGGESTING LITTLE CHANGE NEEDED TO GOING FCST. HEADING INTO NEXT WEEKEND...MODELS ADVERTISE SHORTWAVE ENERGY OVER IA QUICKLY LIFTING TO THE GREAT LAKES REGION LATE THURSDAY NIGHT. MEANWHILE UPSTREAM...A DEEP LONGWAVE TROF IS PROGGED TO EXTEND FROM CNTRL CANADA ALL THE WAY TO THE SWRN CONUS. ON FRIDAY AS THE WRN TROF GRADUALLY MIGRATES EAST...INTENSE BAROCLINIC ZONE BEGINS SWEEPING ACROSS THE NRN/CNTRL PLAINS WITH THE LEADING EDGE OF THE BOUNDARY REACHING THE CWA BY EARLY AFTN. COMBINATION OF INCREASING MOISTURE AND STOUT AGEOSTROPHIC LIFT ALONG DEEP FRONTOGENETIC LYR SHOULD BE ENOUGH TO INDUCE LIGHT SNOW ACTIVITY DURING THE FROPA FRIDAY NIGHT. ON SATURDAY...APPEARS TO BE A SMALL CHANCE FOR LIGHT POST-FRONTAL SNOW ACTIVITY PER THE ECM. 300-500MB QVEC CONVERGENCE IMPLYING LIFT VIA DPVA WHEN POTENT OR MAX ROUNDS THE BASE OF THE WRN TROF AND LIFTS ACROSS THE CNTRL PLAINS. ON THE OTHER HAND...GFS AND CMC BOTH SUGGESTING THE DEEP CAA WILL BE ADEQUATE TO SUPPRESS ANY LIFT VIA DPVA. WILL OPTED FOR TOKEN 20S JUST IN CASE ECM SOLUTION WOULD VERIFY. OTHERWISE...TEMPS WILL PLUMMET OVER THE PLAINS NEXT WEEKEND INTO EARLY NEXT WEEK. EXPECT HIGHS SAT-MON WILL STRUGGLE TO REACH THE LOWER/MID 20S. DEE && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ 99/99
AREA FORECAST DISCUSSION
NWS RALEIGH NC
305 AM EST TUE JAN 8 2013 .SYNOPSIS... HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH WEDNESDAY. A BACKDOOR COLD FRONT WILL PUSH INTO THE REGION THURSDAY... THEN RETURN NORTH AS A WARM FRONT LATE FRIDAY. && .NEAR TERM /THROUGH WEDNESDAY/... AS OF 305 AM TUESDAY... TODAY... A 1030MB SURFACE HIGH CENTERED OVER THE VA TIDEWATER AREA EXTENDS SOUTHWEST ACROSS CENTRAL NC THIS MORNING. ALOFT...A WEAK DISTURBANCES WITHIN THE BROAD SUBTROPICAL RIDGE IS MOVING OVER THE CWA...WITH THE ASSOCIATED CIRRUS CURRENTLY EXITING THE NORTHERN COASTAL PLAIN. BENEATH A STRONG AND DRY SUBSIDENCE INVERSION AT 900MB...INCREASINGLY VEERED LOW LEVEL FLOW IS BEGINNING TO ADVECT MOISTURE INLAND. IR IMAGERY SHOWS STRATUS EXPANDING FROM COASTAL CAROLINA NORTHWESTWARD INTO THE SOUTHERN COASTAL PLAIN AND SANDHILLS. THE HRRR MOISTURE FIELDS...WHICH APPEAR TO HAVE A GOOD HANDLE ON THIS CLOUD COVER...SHOW MOISTURE SPREADING NORTH THROUGH THE PIEDMONT THIS MORNING. IF THE CLOUD COVER IS AS THICK AND WIDESPREAD AS THE NAM AND RAP FORECAST SOUNDINGS SHOW....HIGHS WILL BE A GOOD 5-7 DEGREES BELOW FULL SUN THICKNESS VALUES TODAY. PREFER THE COOLER MET MOS BASED ON CURRENT TRENDS...51-58 WEST TO EAST. OTHERWISE..NO SENSIBLE WEATHER IMPACTS TODAY AS MOISTURE IS MUCH TOO SHALLOW AND THE MID LEVELS TOO DRY FOR ANY PRECIP. TONIGHT... CONTINUATION OF THE RETURN FLOW AROUND OF THE ELONGATING SURFACE RIDGE AXIS WILL LEAD TO STRATUS AGAIN OVERNIGHT. FORECAST SOUNDINGS ARE SUPPORTED BY HIGH SREF PROBABILITIES OF LOW CEILINGS OVER THE WESTERN PIEDMONT. HIGH CLOUDS SHOULD ALSO BE ON THE INCREASE AS MOISTURE STREAMS IN FROM THE SOUTHWEST AHEAD OF AN UPPER LOW MOVING SLOWLY ACROSS THE TX/MEXICO BORDER. MOSTLY CLOUDY SKIES SHOULD LIMIT ANY FOG POTENTIAL...BUT WITH DEWPOINTS CREEPING UP INTO THE LOWER 40S AND WEAK WINDS WITHIN THE SURFACE RIDGE AXIS...THERE COULD BE SOME PATCHY FOG IN THE SOUTH AND EAST LATE TONIGHT. LOWS 37-42. WEDNESDAY... THE AIRMASS OVER CENTRAL NC WILL CONTINUE TO MOISTEN WEDNESDAY AS HIGH PRESSURE LINGERS OFF THE COAST AND RETURN FLOW PERSISTS. AN UNSEASONABLY STRONG SUBTROPICAL RIDGE WILL HOLD OVER THE SOUTHEAST US...WHILE ONE SHORTWAVE CROSSES THE GREAT LAKES REGION AND THE AFOREMENTIONED UPPER LOW OVER TX BEGINS TO LIFT NORTH THROUGH THE SOUTHERN PLAINS. MODELS GENERATE SOME VERY LIGHT QPF LATE IN THE DAY ACROSS THE SOUTHERN CWA...BUT THIS APPEARS TO BE OVERDONE GIVEN THE LACK OF FORCING. WILL MAINTAIN A DRY FORECAST FOR WEDNESDAY. LOW LEVEL THICKNESSES APPROACH 1370M BY WEDNESDAY AFTERNOON..BUT AS PW VALUES RISE TO NEAR ONE INCH... THERE SHOULD AGAIN BE SOME IMPACT OF CLOUD COVER ON HEATING. HIGHS 61-66. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 300 AM TUESDAY... A HYBRID COLD AIR DAMMING EVENT LIKELY LATE THURSDAY INTO FRIDAY... THE EVOLVING PATTERN CONSISTING OF A DEEP WEST-CENTRAL U.S. TROUGH AND STRONGLY RISING UPPER HEIGHTS FROM THE CARIBBEAN THROUGH THE SOUTHEAST U.S. LATE WEEK INTO THE WEEKEND WILL EVENTUALLY MEAN A WARM AND MOSTLY DRY PERIOD FOR OUR REGION THIS WEEKEND. BEFORE THAT OCCURS... A HYBRID CAD EVENT IS EXPECTED TO DEVELOP OVER THE PIEDMONT DAMMING REGION THURSDAY AND LAST INTO FRIDAY. THE WARMING ASSOCIATED WITH RISING HEIGHTS ALOFT WILL INITIALLY BE OFFSET BY THE STRONG (1035+ MB) SURFACE HIGH THAT IS EXPECTED TO BUILD EAST FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST THURSDAY INTO EARLY FRIDAY. THE STRENGTH AND POSITION OF THIS HIGH PRESSURE IS VERY FAVORABLE FOR CAD DEEP INTO OUR REGION. THE HIGH IS FORECAST TO BE PROGRESSIVE AS THE MID/UPPER FLOW OVER THE NE US BECOMES CONFLUENT BY THE WEEKEND... MAKING THIS A HYBRID CAD EVENT... AND ONE THAT WILL ERODE A BIT MORE QUICKLY THAN CLASSICAL CAD EPISODES. INITIALLY ON THURSDAY... THE HIGH IS EXPECTED TO BUILD SOUTH... DOWN THE EASTERN SEABOARD... WHEN THE SOUTHERN PLAINS STORM SYSTEM IS FORECAST TO TRACK NE THROUGH THE OHIO VALLEY THU NIGHT. WARM MOIST AIR IS EXPECTED TO OVERRUN THE COOL STABLE LAYER EAST OF THE MOUNTAINS THU NIGHT AND FRIDAY... WITH AREAS OF RAIN DEVELOPING/OVERSPREADING THE REGION. THIS WILL ALLOW THE CAD EVENT TO SHAPE UP THURSDAY NIGHT INTO FRIDAY. THE EVENTUAL DEPTH AND DURATION OF THE CAD SHOULD LARGELY BE DRIVEN BY THE AMOUNT OF QPF THOSE PERIODS INTO THE COOL STABLE AIR... LOCKING THE CAD IN PLACE. THE CURRENT FAVORED BLEND OF THE LATEST GFS/EC OPERATIONAL MODELS AND EC ENSEMBLES INDICATE THE QPF TO REACH THE CRITICAL 0.12 TO 0.25 THRESHOLD IN THE PIEDMONT DAMMING REGION... SUFFICIENT TO LOCK IN THE CAD THURSDAY NIGHT INTO EARLY FRIDAY. IF THIS IS REALIZED... THIS WILL DELAY THE THE WARM FRONT FROM SURGING THROUGH CENTRAL NC ON FRIDAY MORNING. IT WOULD TAKE MUCH OF THE DAY FOR THE DAMMING (PARTICULARLY THE RESIDUAL AFFECTS - LOWS CLOUDS/FOG/DRIZZLE) TO ERODE. CURRENT THINKING IS THAT THE PIEDMONT TRIAD REGION MAY VERY WELL HAVE CAD AFFECTS INTO SAT MORNING. SENSIBLE WEATHER... PARTLY CLOUDY WEDNESDAY NIGHT WITH LOWS IN THE UPPER 30S TO MID 40S. THURSDAY... INCREASING CLOUDS NE... MOSTLY CLOUDY TO CLOUDY WEST. WINDS BECOMING ENE. HIGHS IN THE 50S TO LOWER 60S SE. THURSDAY NIGHT AND EARLY FRIDAY... RAIN LIKELY NW AND A CHANCE SE. COOL IN THE DAMMING REGION. LOWS IN THE 40S. LINGERING LOW CLOUDS AND LIGHT RAIN/DRIZZLE FRIDAY IN THE DAMMING REGION. BECOMING MOSTLY CLOUDY SE/WARMER. HIGHS 55 NW TO UPPER 60S SE. PARTLY CLOUDY TO CLOUDY FRIDAY NIGHT. WARMER. LOWS 45-55. AREAS OF FOG/LOW CLOUDS AGAIN LIKELY NW. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 300 TUESDAY... THE LATEST MODELS SUPPORT THE SLOWER TIMING OF THE COLD FRONT BY EARLY NEXT WEEK. THIS WILL ENSURE A WEEKEND OF WARM DRY WEATHER WITH TEMPS 20 TO 30 DEGREES ABOVE NORMAL. WE WILL HOLD OFF MENTION OF ANY SHOWERS UNTIL SUNDAY NIGHT OR MONDAY. BECOMING PARTLY CLOUDY SATURDAY. BREEZY AND WARMER. HIGHS IN THE UPPER 60S TO MID 70S. LOWS SAT NIGHT IN THE 50S (AVERAGE HIGHS ARE 48-53). SUNDAY... PARTLY SUNNY. HIGHS LOWER TO MID 70S. MONDAY... MOSTLY CLOUDY WITH A CHANCE OF SHOWERS. HIGHS IN THE 60S TO LOWER 70S SE. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 1240 AM TUESDAY... WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE CAROLINAS. STRATUS HAS DEVELOPED OVER THE SC COASTAL AREAS AND IS STARTING TO SPREAD INLAND TO THE WEST-NORTHWEST. SATELLITE TRENDS WOULD SUGGEST THIS MOISTURE COULD REACH KFAY BY 12Z...AND HRRR MODEL CEILING FORECASTS SUPPORT THIS. THUS...THERE IS INCREASING CONFIDENCE THAT MVFR...OR NEAR MVFR CEILINGS WILL MOVE DEVELOP AT KFAY BY AROUND 12 AND KRDU/KRWI BY 15Z. WILL ALSO CONTINUE A LOW CONFIDENCE CHANCE OF LOCALIZED FOG/STRATUS AT KRWI THROUGH 12Z. DAYTIME HEATING MAY CAUSE THE CLOUD DECK TO SCATTER A BIT BY THIS AFTERNOON...BUT THERE SHOULD STILL BE ENOUGH MOISTURE BELOW A STRONG SUBSIDENCE INVERSION TO KEEP CONDITIONS ON AT LEAST THE THE EDGE OF MVFR. FURTHER WEST AT KGSO/KINT...MVFR CONDITIONS ARE NOT RULED OUT...BUT CONFIDENCE IS MUCH LOWER. TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT) OUTLOOK... AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT APPROACHES FROM THE SOUTH-SOUTHWEST. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...SMITH SHORT TERM...BADGETT LONG TERM...BADGETT AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
300 AM EST TUE JAN 8 2013 .SYNOPSIS... HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH WEDNESDAY. A BACKDOOR COLD FRONT WILL PUSH INTO THE REGION THURSDAY... THEN RETURN NORTH AS A WARM FRONT LATE FRIDAY. && .NEAR TERM /THROUGH TUESDAY/... AS OF 850 PM MONDAY... TONIGHT: HIGH PRESSURE WILL CONTINUE TO SHIFT EASTWARD OVERNIGHT KEEPING SKIES MOSTLY CLEAR. CURRENT SATELLITE AND WATER VAPOR TRENDS SHOW AN AREA OF HIGH LEVEL MOISTURE BRAINING SOME CLOUDS OVER UPSTATE SOUTH CAROLINA THAT MAY AFFECT CENTRAL NC OVER THE NEXT SEVERAL HOURS. ANY LINGERING CLOUDINESS ASIDE...LOW TEMPERATURE SHOULD BE ABLE TO DROP INTO THE UPPER 20S IN MOST LOCATIONS TO NEAR 30 IN THE SOUTH WHERE SOME MID LEVEL STRATUS MAY CREEP IN FROM THE SOUTHEAST JUST BEFORE SUNRISE. FOR THE MOST PART DEWPOINT DEPRESSIONS SHOULD BE LARGE ENOUGH TO KEEP FOG OR LOW STRATUS FROM FORMING BUT THERE IS AN OUTSIDE CHANCE THAT IT COULD FORM AT KRWI DURING THE EARLY MORNING HOURS. WINDS WILL BE LARGELY CALM OVERNIGHT BUT WILL GRADUALLY SHIFT TO A SOUTHWESTERLY DIRECTION AS THE HIGH PUSHES OUT TO SEA. -ELLIS TUESDAY: LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA ALONG WITH A WEAK UPPER LEVEL DISTURBANCE MOVING ACROSS THE AREA IN THE SW FLOW. NOT EXPECTING ANY PRECIP AS WE WILL HAVE A LOT OF DRY MID LEVEL AIR AND NOT ENOUGH ISENTROPIC LIFT AND MOISTURE IN THE LOW LEVELS. LOW LEVEL MOISTURE RETURN SHOULD ALLOW FOR AT LEAST PARTLY SUNNY TO EVEN MOSTLY CLOUDY SKIES ACROSS A GOOD PORTION OF THE AREA TUESDAY... WITH THE EARLIEST AND MOST CLOUDS ACROSS THE WEST AND SOUTH/SOUTHWEST... WITH THE LEAST IN THE NORTHEAST. AFTERNOON LOW LEVEL THICKNESS VALUES ARE PROGGED TO BE AROUND 15 METERS HIGHER THAN TODAY. HOWEVER... THANKS TO THE INCREASE IN CLOUD COVER HIGH TEMPS OVER MOST OF THE AREA WILL NOT BE ABLE TO REACH THEIR FULL SUN HIGHS.... ESPECIALLY IN THE WEST... WHICH IS SHOWN IN THE STATISTICAL GUIDANCE WELL. THUS... WILL GO WITH HIGH TEMPS RANGING FROM THE LOWER 50S WEST TO UPPER 50S/NEAR 60 EAST/SOUTHEAST. -BSD && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... AS IF 300 AM TUESDAY... A HYBRID COLD AIR DAMMING EVENT LIKELY LATE THURSDAY INTO FRIDAY... THE EVOLVING PATTERN CONSISTING OF A DEEP WEST-CENTRAL U.S. TROUGH AND STRONGLY RISING UPPER HEIGHTS FROM THE CARIBBEAN THROUGH THE SOUTHEAST U.S. LATE WEEK INTO THE WEEKEND WILL EVENTUALLY MEAN A WARM AND MOSTLY DRY PERIOD FOR OUR REGION THIS WEEKEND. BEFORE THAT OCCURS... A HYBRID CAD EVENT IS EXPECTED TO DEVELOP OVER THE PIEDMONT DAMMING REGION THURSDAY AND LAST INTO FRIDAY. THE WARMING ASSOCIATED WITH RISING HEIGHTS ALOFT WILL INITIALLY BE OFFSET BY THE STRONG (1035+ MB) SURFACE HIGH THAT IS EXPECTED TO BUILD EAST FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST THURSDAY INTO EARLY FRIDAY. THE STRENGTH AND POSITION OF THIS HIGH PRESSURE IS VERY FAVORABLE FOR CAD DEEP INTO OUR REGION. THE HIGH IS FORECAST TO BE PROGRESSIVE AS THE MID/UPPER FLOW OVER THE NE US BECOMES CONFLUENT BY THE WEEKEND... MAKING THIS A HYBRID CAD EVENT... AND ONE THAT WILL ERODE A BIT MORE QUICKLY THAN CLASSICAL CAD EPISODES. INITIALLY ON THURSDAY... THE HIGH IS EXPECTED TO BUILD SOUTH... DOWN THE EASTERN SEABOARD... WHEN THE SOUTHERN PLAINS STORM SYSTEM IS FORECAST TO TRACK NE THROUGH THE OHIO VALLEY THU NIGHT. WARM MOIST AIR IS EXPECTED TO OVERRUN THE COOL STABLE LAYER EAST OF THE MOUNTAINS THU NIGHT AND FRIDAY... WITH AREAS OF RAIN DEVELOPING/OVERSPREADING THE REGION. THIS WILL ALLOW THE CAD EVENT TO SHAPE UP THURSDAY NIGHT INTO FRIDAY. THE EVENTUAL DEPTH AND DURATION OF THE CAD SHOULD LARGELY BE DRIVEN BY THE AMOUNT OF QPF THOSE PERIODS INTO THE COOL STABLE AIR... LOCKING THE CAD IN PLACE. THE CURRENT FAVORED BLEND OF THE LATEST GFS/EC OPERATIONAL MODELS AND EC ENSEMBLES INDICATE THE QPF TO REACH THE CRITICAL 0.12 TO 0.25 THRESHOLD IN THE PIEDMONT DAMMING REGION... SUFFICIENT TO LOCK IN THE CAD THURSDAY NIGHT INTO EARLY FRIDAY. IF THIS IS REALIZED... THIS WILL DELAY THE THE WARM FRONT FROM SURGING THROUGH CENTRAL NC ON FRIDAY MORNING. IT WOULD TAKE MUCH OF THE DAY FOR THE DAMMING (PARTICULARLY THE RESIDUAL AFFECTS - LOWS CLOUDS/FOG/DRIZZLE) TO ERODE. CURRENT THINKING IS THAT THE PIEDMONT TRIAD REGION MAY VERY WELL HAVE CAD AFFECTS INTO SAT MORNING. SENSIBLE WEATHER... PARTLY CLOUDY WEDNESDAY NIGHT WITH LOWS IN THE UPPER 30S TO MID 40S. THURSDAY... INCREASING CLOUDS NE... MOSTLY CLOUDY TO CLOUDY WEST. WINDS BECOMING ENE. HIGHS IN THE 50S TO LOWER 60S SE. THURSDAY NIGHT AND EARLY FRIDAY... RAIN LIKELY NW AND A CHANCE SE. COOL IN THE DAMMING REGION. LOWS IN THE 40S. LINGERING LOW CLOUDS AND LIGHT RAIN/DRIZZLE FRIDAY IN THE DAMMING REGION. BECOMING MOSTLY CLOUDY SE/WARMER. HIGHS 55 NW TO UPPER 60S SE. PARTLY CLOUDY TO CLOUDY FRIDAY NIGHT. WARMER. LOWS 45-55. AREAS OF FOG/LOW CLOUDS AGAIN LIKELY NW. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 300 TUESDAY... THE LATEST MODELS SUPPORT THE SLOWER TIMING OF THE COLD FRONT BY EARLY NEXT WEEK. THIS WILL ENSURE A WEEKEND OF WARM DRY WEATHER WITH TEMPS 20 TO 30 DEGREES ABOVE NORMAL. WE WILL HOLD OFF MENTION OF ANY SHOWERS UNTIL SUNDAY NIGHT OR MONDAY. BECOMING PARTLY CLOUDY SATURDAY. BREEZY AND WARMER. HIGHS IN THE UPPER 60S TO MID 70S. LOWS SAT NIGHT IN THE 50S (AVERAGE HIGHS ARE 48-53). SUNDAY... PARTLY SUNNY. HIGHS LOWER TO MID 70S. MONDAY... MOSTLY CLOUDY WITH A CHANCE OF SHOWERS. HIGHS IN THE 60S TO LOWER 70S SE. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 1240 AM TUESDAY... WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE CAROLINAS. STRATUS HAS DEVELOPED OVER THE SC COASTAL AREAS AND IS STARTING TO SPREAD INLAND TO THE WEST-NORTHWEST. SATELLITE TRENDS WOULD SUGGEST THIS MOISTURE COULD REACH KFAY BY 12Z...AND HRRR MODEL CEILING FORECASTS SUPPORT THIS. THUS...THERE IS INCREASING CONFIDENCE THAT MVFR...OR NEAR MVFR CEILINGS WILL MOVE DEVELOP AT KFAY BY AROUND 12 AND KRDU/KRWI BY 15Z. WILL ALSO CONTINUE A LOW CONFIDENCE CHANCE OF LOCALIZED FOG/STRATUS AT KRWI THROUGH 12Z. DAYTIME HEATING MAY CAUSE THE CLOUD DECK TO SCATTER A BIT BY THIS AFTERNOON...BUT THERE SHOULD STILL BE ENOUGH MOISTURE BELOW A STRONG SUBSIDENCE INVERSION TO KEEP CONDITIONS ON AT LEAST THE THE EDGE OF MVFR. FURTHER WEST AT KGSO/KINT...MVFR CONDITIONS ARE NOT RULED OUT...BUT CONFIDENCE IS MUCH LOWER. TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT) OUTLOOK... AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT APPROACHES FROM THE SOUTH-SOUTHWEST. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BSD NEAR TERM...ELLIS/BSD SHORT TERM...KC LONG TERM...KC AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1240 AM EST TUE JAN 8 2013 .SYNOPSIS... HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH MIDWEEK. && .NEAR TERM /THROUGH TUESDAY/... AS OF 850 PM MONDAY... TONIGHT: HIGH PRESSURE WILL CONTINUE TO SHIFT EASTWARD OVERNIGHT KEEPING SKIES MOSTLY CLEAR. CURRENT SATELLITE AND WATER VAPOR TRENDS SHOW AN AREA OF HIGH LEVEL MOISTURE BRAINING SOME CLOUDS OVER UPSTATE SOUTH CAROLINA THAT MAY AFFECT CENTRAL NC OVER THE NEXT SEVERAL HOURS. ANY LINGERING CLOUDINESS ASIDE...LOW TEMPERATURE SHOULD BE ABLE TO DROP INTO THE UPPER 20S IN MOST LOCATIONS TO NEAR 30 IN THE SOUTH WHERE SOME MID LEVEL STRATUS MAY CREEP IN FROM THE SOUTHEAST JUST BEFORE SUNRISE. FOR THE MOST PART DEWPOINT DEPRESSIONS SHOULD BE LARGE ENOUGH TO KEEP FOG OR LOW STRATUS FROM FORMING BUT THERE IS AN OUTSIDE CHANCE THAT IT COULD FORM AT KRWI DURING THE EARLY MORNING HOURS. WINDS WILL BE LARGELY CALM OVERNIGHT BUT WILL GRADUALLY SHIFT TO A SOUTHWESTERLY DIRECTION AS THE HIGH PUSHES OUT TO SEA. -ELLIS TUESDAY: LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA ALONG WITH A WEAK UPPER LEVEL DISTURBANCE MOVING ACROSS THE AREA IN THE SW FLOW. NOT EXPECTING ANY PRECIP AS WE WILL HAVE A LOT OF DRY MID LEVEL AIR AND NOT ENOUGH ISENTROPIC LIFT AND MOISTURE IN THE LOW LEVELS. LOW LEVEL MOISTURE RETURN SHOULD ALLOW FOR AT LEAST PARTLY SUNNY TO EVEN MOSTLY CLOUDY SKIES ACROSS A GOOD PORTION OF THE AREA TUESDAY... WITH THE EARLIEST AND MOST CLOUDS ACROSS THE WEST AND SOUTH/SOUTHWEST... WITH THE LEAST IN THE NORTHEAST. AFTERNOON LOW LEVEL THICKNESS VALUES ARE PROGGED TO BE AROUND 15 METERS HIGHER THAN TODAY. HOWEVER... THANKS TO THE INCREASE IN CLOUD COVER HIGH TEMPS OVER MOST OF THE AREA WILL NOT BE ABLE TO REACH THEIR FULL SUN HIGHS.... ESPECIALLY IN THE WEST... WHICH IS SHOWN IN THE STATISTICAL GUIDANCE WELL. THUS... WILL GO WITH HIGH TEMPS RANGING FROM THE LOWER 50S WEST TO UPPER 50S/NEAR 60 EAST/SOUTHEAST. -BSD && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... AS OF 300 PM MONDAY... ELONGATED AREA OF HIGH PRESSURE AT THE SURFACE EXTENDING WNW TO ESE OVER NC THROUGH THE PERIOD. RETURN FLOW AROUND THE HIGH WILL ADVECT MOISTURE INTO THE CAROLINAS FROM THE ATLANTIC. WILL LIKELY SEE AN INCREASE IN LOW CLOUDS TUESDAY NIGHT. GOOD ISENTROPIC UPGLIDE SHOULD YIELD SOME LOW STRATUS ACROSS CENTRAL NC WEDNESDAY MORNING. HIGH CLOUDS WILL SPREAD EASTWARD ACROSS THE AREA AHEAD OF A LOW PRESSURE SYSTEM TO THE WEST. THIS PART OF THE FORECAST SHOULD REMAIN MOSTLY DRY...WITH THE CHANCE OF A FEW SPRINKLES ACROSS THE SOUTH THURSDAY MORNING. EXPECT HIGHS ON WEDNESDAY IN THE LOW TO MID 60S...WITH LOWS INCREASING FROM MID 30S TO NEAR 40 TUESDAY NIGHT TO THE LOW TO UPPER 40S WEDNESDAY NIGHT. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 310 PM MONDAY... THURSDAY THROUGH SATURDAY NIGHT: LOW PRESSURE OVER TX WEDNESDAY NIGHT WILL GET ABSORBED IN THE LONGWAVE TROUGH AS IT MOVE NORTHEAST ON THURSDAY. GOOD INFLUX OF GULF MOISTURE AHEAD OF THE SYSTEM WILL HELP GENERATE PRECIP AHEAD OF IT. THE MAJORITY OF THE PRECIP WILL RIDE NE OVER THE H85 HIGH MEANDERING OFF THE SC COAST. BEST CHANCES FOR PRECIP OVER CENTRAL NC WILL BE A RESULT OF ISENTROPIC UPGLIDE FROM THE MOIST RETURN FLOW AROUND THE HIGH. A HYBRID COLD AIR DAMMING EVENT IS LIKELY LATE THIS WEEK AND POSSIBLY INTO THE WEEKEND AS THE SURFACE HIGH PRESSURE BUILDS INTO THE NC PIEDMONT FROM THE NE...BEGINNING LATE THURSDAY. THE FORECASTED PRECIP IN THE NORTHWEST THURSDAY AND FRIDAY WILL HELP TO MOISTEN AND COOL THE LOW LEVELS AND LOCK IN THE COLD AIR. WITH THE DAMMING IN PLACE AND THE WARM MOIST AIR EXPECTED TO OVERRUN THE COOL STABLE LAYER IN THE NW...WILL LIKELY SEE AN EXTENDED PERIOD OF OVERCAST SKIES...LIGHT RAIN IN THE FAVORED DAMMING REGION...AND A STRONG GRADIENT IN TEMPERATURE FROM THE NW TO SE PORTION OF THE AREA. THERE IS SIGNIFICANT UNCERTAINTY WITH REGARD TO WHEN THE CAD WILL ERODE...WHICH WILL GREATLY IMPACT TEMPERATURES DURING THAT TIME. AT THIS TIME...HAVE KEPT THE WEDGE OF COLD AIR IN THROUGH SATURDAY. HIGH TEMPS ON THURSDAY SHOULD BE IN THE MID 50S TO LOW 60S AND OVERNIGHT LOWS NEAR 40 IN THE NE TO UPPER 40S SW. WITH THE COLD AIR IN PLACE ACROSS THE NW...CURRENTLY HAVE HIGHS ON FRIDAY IN THE MID 50S NW TO MID 60S SE INCREASING ON SATURDAY TO MID 60S NW TO LOW 70S SE. OVERNIGHT LOWS FRIDAY AND SATURDAY NIGHTS IN THE MID 40S NW TO LOW 50S SE. SUNDAY THROUGH MONDAY: ASSUMING THE WEDGE ERODES ON SATURDAY...WILL SEE IMPROVING WEATHER CONDITIONS ON SUNDAY. MODELS CURRENTLY SHOW THE NEXT WEATHER SYSTEM MOVING INTO THE WEST MONDAY MORNING...WITH THE BEST CHANCES FOR PRECIP ACROSS THE AREA LATE MONDAY MORNING AND INTO THE AFTERNOON. HIGH TEMPS ON SUNDAY ARE FORECAST IN THE UPPER 60S TO LOW 70S. WITH INCREASING CLOUDINESS AND CHANCES FOR SHOWERS...HIGHS ON MONDAY MAY BE A FEW DEGREES COOLER...LOW 60S TO NEAR 70. OVERNIGHT LOWS UPPER 40S TO LOW 50S. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 1240 AM TUESDAY... WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE CAROLINAS. STRATUS HAS DEVELOPED OVER THE SC COASTAL AREAS AND IS STARTING TO SPREAD INLAND TO THE WEST-NORTHWEST. SATELLITE TRENDS WOULD SUGGEST THIS MOISTURE COULD REACH KFAY BY 12Z...AND HRRR MODEL CEILING FORECASTS SUPPORT THIS. THUS...THERE IS INCREASING CONFIDENCE THAT MVFR...OR NEAR MVFR CEILINGS WILL MOVE DEVELOP AT KFAY BY AROUND 12 AND KRDU/KRWI BY 15Z. WILL ALSO CONTINUE A LOW CONFIDENCE CHANCE OF LOCALIZED FOG/STRATUS AT KRWI THROUGH 12Z. DAYTIME HEATING MAY CAUSE THE CLOUD DECK TO SCATTER A BIT BY THIS AFTERNOON...BUT THERE SHOULD STILL BE ENOUGH MOISTURE BELOW A STRONG SUBSIDENCE INVERSION TO KEEP CONDITIONS ON AT LEAST THE THE EDGE OF MVFR. FURTHER WEST AT KGSO/KINT...MVFR CONDITIONS ARE NOT RULED OUT...BUT CONFIDENCE IS MUCH LOWER. TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT) OUTLOOK... AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT APPROACHES FROM THE SOUTH-SOUTHWEST. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BSD NEAR TERM...ELLIS/BSD SHORT TERM...KC LONG TERM...KC AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1206 AM EST TUE JAN 8 2013 .SYNOPSIS... A DEVELOPING OFFSHORE COASTAL TROUGH WILL PARALLEL THE CAROLINA COAST THROUGH TUESDAY...THEN DISSIPATE ON WEDNESDAY. A STORM SYSTEM...MOVING NORTHEAST OUT OF THE PLAIN STATES...WILL BRING A WARM FRONT ACROSS THE AREA LATE WEEK. HIGH PRESSURE WILL BRING WARM TEMPERATURES AND DRY WEATHER FOR THE WEEKEND. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... AS OF 1035 PM MONDAY...MID TO HIGH LEVEL CLOUDS CONTINUE TO EXPAND NORTHWARD ACROSS THE FA THIS EVENING AND OVERNIGHT...WITH A LOW DECK POSSIBLE ALONG THE IMMEDIATE COAST AS LATEST HRRR MODEL INDICATES AN INVERTED SFC TROF TO DEVELOP JUST OFFSHORE LATE TONIGHT. OVERNIGHT TEMPS/DEWPOINTS CONTINUE TO BE MASSAGED...MOSTLY TOWARD THE UPWARD SIDE DUE TO INCREASING OPAQUE SKY COVER. WINDS ACROSS THE INLAND COUNTIES WILL HAVE THE POTENTIAL TO DECOUPLE AS THE CENTER OF THE SFC HIGH EXTENDS ACROSS THIS AREA. COULD OBSERVE NEAR FREEZING READINGS IF RAD COOLING CONDITIONS PERSIST THROUGH THE OVERNIGHT. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...AS WEDGE OF HIGH PRESSURE HANGS ON AT THE SURFACE IN A WEDGE-LIKE SCENARIO THE MAIN FORECAST ISSUE ON TUES SEEMS TO BE THE EXTENT OF CLOUD COVER THAT MANAGES TO DEVELOP. E TO NE WINDS BENEATH WARM ADVECTION/SW FLOW AT 850 MB LEADS TO A NEARLY ISOTHERMAL LAYER FROM VERY ROUGHLY 950-850MB WITH FAIRLY HIGH RH. ABOVE THIS LAYER IS VERY DRY AIR ASSOCIATED WITH SUBSIDENCE INVERSION. ACTUAL MIXING IS FORECAST TO BE QUITE SHALLOW SO THIS DRY AIR MAY NOT COME TO BEAR TOO MUCH WITH RESPECT TO CLOUD COVER OBSERVED AT THE SURFACE...I JUST WONDER IF GUIDANCE IS BRINGING IN TOO MUCH MOISTURE OFF OF THE ATLANTIC. THE ACTUAL FRONTAL BAND SHOULD NOT MAKE IT THIS FAR NORTH AND WEST AND GUIDANCE IS IN FAIRLY GOOD AGREEMENT THAT LOW LEVEL ISENTROPIC UPGLIDE IS VERY SLOW OR EVEN NOT FORECAST TO DEVELOP UNTIL NIGHTTIME. SHOW A GRADUAL UPWARD TREND IN SKY COVER BUT WILL CAP VALUES NEAR UPPER RANGES OF PARTLY CLOUDY SAVE FOR SOUTHERN ZONES WHICH WILL REGISTER MOSTLY CLOUDY IN TEXT PRODUCTS IN ALL LIKELIHOOD. SMALL POPS HINTED AT IN GUIDANCE SEEMS IMPLAUSIBLE DUE TO AFOREMENTIONED DRY AIR. DRIZZLE SEEMS LIKE WORST CASE. BY WEDNESDAY THE HIGH SHOWS VERY LITTLE MOVEMENT BUT WEAKENS SUFFICIENTLY TO NO LONGER IMPLY COOL AIR WEDGING. MIXING IS FORECAST TO REMAIN QUITE SHALLOW AND SO SOME OF THE LOW LEVEL WARM AIR ADVECTION MAY NOT BE REALIZED AT THE SURFACE (ESPECIALLY IF THE CLOUD COVER CONTINUES TO INCREASE). BASED UPON THIS AND SIMILAR CONCERN NOTED BY SOME NEIGHBORS HAVE TRIMMED WED HIGHS A FEW DEGREES BELOW GUIDANCE. MOISTURE PROFILE A LITTLE DEEPER IN FORECAST SOUNDINGS BUT RAIN CHANCES WILL STAY CAPPED AT SLIGHT CHANCE IN THE ABSENCE OF ANY REAL FORCING MECHANISM. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 3 PM MONDAY...MAIN DETAILS OF THE SYNOPTIC PATTERN FOR THE EXTENDED REMAIN IN PLACE THIS AFTERNOON AS A STRONG CLOSED LOW WILL MOVE QUICKLY THROUGH THE MIDWEST AND SHEAR OUT. THE FLOW BETWEEN THIS FEATURE AND AN ANOMALOUS RIDGE TO THE SOUTHEAST WILL CREATE A VERY WARM AND PERSISTENT FLOW. THE LOW...BEFORE SHEARING OUT AND FILLING IS 3-4 STAND DEVIATIONS BELOW NORMAL AND THE RIDGE IS 1-2 ABOVE. 850MB TEMPERATURES OF 13-15 DEGREES C WILL ADVECT INTO THE AREA FOR THE WEEKEND. MEX GUIDANCE IS ADVERTISING WIDESPREAD 70S FOR THE THIRD DAY IN A ROW AND THE FORECAST HAS BEEN ADJUSTED UPWARD AS EVEN THE COOLER HPC NUMBERS ARE MOSTLY IN THE 70S FOR THE WEEKEND. THE ONLY RECORD THAT APPEARS IN JEOPARDY AT THIS TIME IS FLORENCE FOR SATURDAY WHICH IS 73 DEGREES. THE KICKER SYSTEM...THE ONE THAT FORCES THE INITIAL DEEP LOW TO MOVE OUT BEGINS TO IMPACT THE REGION MONDAY WITH INCREASED CLOUDINESS AND SLIGHT CHANCE POPS HENCE...SLIGHTLY COOLER TEMPERATURES. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 06Z...CLOUDS WILL LOWER WITH TIME AND WILL FORECAST CEILINGS LOWERING FROM VFR TO MVFR AT ALL THE TERMINALS THROUGH DAYBREAK AS A COASTAL TROUGH CONTINUES TO DEVELOP. MOIST RETURN FLOW AROUND HIGH PRESSURE CENTERED OFFSHORE WILL KEEP BKN TO AT TIMES OVC CONDITIONS AFTER DAYBREAK AS WELL. CEILINGS ARE EXPECTED TO LIFT TO VFR 12-14Z. EXTENDED OUTLOOK...POSSIBLE MVFR CIGS/VSBYS WEDNESDAY ASSOCIATED WITH A COASTAL TROUGH. SLIGHT CHANCE OF SHOWERS WEDNESDAY AND THURSDAY. VFR DEVELOPING FRIDAY AND PERSISTING THROUGH SATURDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF MIDNIGHT TUESDAY...HEADLINED SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH 11 AM TUE. A DEVELOPING COASTAL TROUGH WAS TIGHTENING THE PRESSURE GRADIENT ACROSS THE WATERS...RESULTING IN WINDS OF NEAR 20 KT WITH GUSTS NEAR 25 KT. THESE HIGHER WINDS WERE PRODUCING SEAS OF 4 TO 5 FT ACROSS THE MAJORITY OF THE OUTER WATERS. THESE CONDITIONS ARE EXPECTED TO PERSIST THROUGH MUCH OF THE MORNING. THE WIND DIRECTION WILL REMAIN NE OVERNIGHT AS THE TROUGH REMAINS TO OUR E. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...WEDGE-LIKE HIGH PRESSURE IN PLACE ON TUESDAY TO BRING A LIGHT NE FLOW...GENERALLY IN THE 10 TO 15 KT RANGE. SEAS 2 TO 3 FT IN A PREDOMINANT 5 SECOND WIND CHOP. ON WEDNESDAY THE HIGH BOTH WEAKENS AND MOVES EVER SO SLIGHTLY TO THE N. WINDS MAY VEER TO EASTERLY WHILE THEY DROP TO ABOUT 10 KT. THIS WILL CUT OUT THE 3 FT SEAS AND MOST PLACES WILL BE CAPPED AT 2 FT. DOMINANT PERIOD LIKELY STAYS ABOUT 5 OR 6 SECONDS BUT A VERY SMALL 10 SECOND EASTERLY SWELL IS ALSO FORECAST. LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 3 PM MONDAY...MAIN EVENT FOR THE MARINE COMMUNITY WILL BE THE WIND SHIFT OCCURRING FRIDAY MORNING AS A WARM FRONT MOVES ACROSS. CONFIDENCE IS NOT ALL THAT GREAT AT LEAST IN REGARDS TO TIMING AS MEDIUM RANGE GUIDANCE HAS BEEN JUMPING AROUND SOMEWHAT. EXPECT A GRADUAL VEERING FROM NORTHEAST THURSDAY AFTERNOON TO SOUTH BY FRIDAY AT 1200 UTC. SPEEDS REMAIN MARGINAL WITH 10-15 KNOTS. EXPECT MORE WESTERLY WINDS SATURDAY COURTESY OF A GLANCING SHOT FROM A BACKDOOR FRONT. SIGNIFICANT SEAS LOOK FAIRLY CONSISTENT WITH THE WAVEWATCH STILL A BIT ON THE HIGH SIDE. THERE COULD STILL BE A SCEC HEADLINE ESPECIALLY EARLY BUT THE WIND SHIFT SHOULD PRECLUDE A SMALL CRAFT ADVISORY WITH 3-5 FEET EXPECTED. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...DCH/RJD SHORT TERM...MBB LONG TERM...SHK AVIATION...RJD/DL
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1103 PM CST MON JAN 7 2013 .DISCUSSION... SEEING SOME PATCHY FOG ACROSS TYPICAL COOL SPOTS IN NORTHWEST IOWA THIS EVENING. MODELS STILL SHOW AN INCREASE IN MID-HIGH CLOUDS OVER NORTHERN HALF OF THE CWA THROUGH THE NIGHT...WITH SOME THIN CIRRUS ACROSS THE SOUTH. NOT EXPECTING FOG TO GET TOO OUT OF HAND...BUT DID ADD MENTION OF PATCHY DENSE FOG BASED ON VISIBILITY REPORTS FROM SHELDON/SPENCER AREAS. SHELDON AWOS ALSO REPORTING DRIZZLE...BUT CALL TO SHERIFF IN THAT AREA REVEALED ONLY SPOTTY FOG AND NO ICING. HAVE MADE MINOR ADJUSTMENTS TO SOME HOURLY TEMPERATURES THROUGH THE EVENING...BUT OVERALL LOWS SEEM REASONABLE AND SEE NO REASON FOR ANY MAJOR CHANGES THERE AT THIS TIME. UPDATED GRIDS HAVE BEEN SENT. && .AVIATION.../FOR THE 06Z TAF ISSUANCE/ MAIN AVIATION CONCERN THIS PERIOD IS RESIDUAL LOW LEVEL MOISTURE FROM MELTING SNOW...MAINLY IN SOUTHEAST PARTS OF THE AREA WHERE WEAK WINDS AND MINIMAL SKY COVER ARE EXPECTED THROUGH THE EARLY MORNING. HAVE ALREADY SEEN SPOTTY IFR-LIFR VISIBILITY/CEILINGS IN PARTS OF NORTHWEST IOWA AND WITH FAVORABLE DRAINAGE WIND OUT OF THE MISSOURI VALLEY INTO KSUX AIRPORT COULD BRING SIMILAR CONDITIONS TO THAT SITE THROUGH SUNRISE. LIGHT SOUTHERLY WINDS WILL INCREASE A BIT AHEAD OF BOUNDARY SET TO PUSH THROUGH THE REGION TUESDAY AFTERNOON/EVENING. WINDS WILL INCREASE FURTHER BEHIND BOUNDARY...AND MODELS APPEAR TO HANG ON TO TOO COOL SURFACE LAYER TEMPS AND DO NOT ALLOW FOR THE BETTER MIXING THAT PROGGED SURFACE READINGS WOULD ALLOW...SO PUT IN SOME WIND GUSTS DURING THE AFTERNOON EXCEEDING 25 KNOTS AROUND KHON...AND CLOSE TO THRESHOLD FOR KFSD/KSUX A BIT LATER INTO THE AFTERNOON. STRONG WINDS REMAIN JUST OFF THE SURFACE THROUGH THE EVENING...AND WITH VERY SHALLOW INVERSION WILL HANG ONTO THE GUSTY WINDS INTO EVENING. && .PREV DISCUSSION.../ISSUED AT 343 PM CST/ MULTIPLE PLAYERS IN TODAY/S FORECAST FOR TONIGHT INTO TOMORROW. CURRENTLY...MOSTLY CLEAR SKIES ACROSS THE AREA WITH A FEW HIGH CLOUDS ACROSS CENTRAL SOUTH DAKOTA. THE SUNSHINE HAS PROMOTED SNOW MELT...BUT WITH WEAK WINDS AND STRONG INVERSION...MOISTURE REMAINS IN THE NEAR SURFACE LAYER. COULD SEE FOG DEVELOP OVERNIGHT TONIGHT...BUT TRICKY TO PIN POINT WHERE EXACTLY. HRRR CONTINUES TO SUGGEST THAT PATCHY FOG WILL BE POSSIBLY ACROSS THE NORTH...WHILE NAM FOCUSES ON THE SOUTH AND EAST. HAVE SIDED CLOSER TO NAM...BUT WITH WEAK WINDS...COULD GET RADIATIONAL FOG NEARLY ANYWHERE CLEAR SKIES REMAIN FOR A FEW HOURS. AS MENTIONED IN THE MORNING DISCUSSION...AMPLIFYING WAVE MOVING ACROSS THE AREA LATE TONIGHT WITH UPPER LEVEL DIV Q INCREASING AFTER 06Z MAINLY ACROSS THE NORTHERN HALF OF THE FORECAST AREA. WITH FAIRLY DRY AIR THROUGH THE MID LEVELS OF THE ATMOSPHERE...AM NOT EXPECTING ANY PRECIPITATION AND DROPPED MENTION OF SPRINKLES/FLURRIES FROM THE FORECAST. IF FOG DEVELOPS IN THE SOUTHEAST...WILL NEED TO KEEP AN EYE ON DRIZZLE POTENTIAL WITH WEAK LIFT IN THE LOW LEVELS OF THE ATMOSPHERE. COLD FRONT IS POISED TO MOVE THROUGH THE AREA ON TUESDAY. SOUTHERLY WINDS WILL BECOME WEST AND SOMEWHAT GUSTY BEHIND THE FRONT WITH 20-30 KNOTS OF FLOW AT 925 HPA. NOT MUCH IN THE WAY OF COLD AIR ADVECTION BEHIND THE FRONT...AND WITH ONLY MEAGER PRESSURE RISES AND STRONG INVERSION REMAINING ALOFT...WILL STRUGGLE TO GET A LOT OF THE MOMENTUM DOWN THE SURFACE. STRONGEST WINDS WILL LIKELY BE ACROSS THE NORTHERN EDGE OF THE FORECAST AREA WITH STRONGEST GRADIENT WINDS THERE...BUT STILL LOOK TO REMAIN BELOW ADVISORY CRITERIA. UPPER LEVEL TROUGH IS EXPECTED TO DIG ACROSS THE DESERT SOUTHWEST MID WEEK...WHICH PUSHES THE RIDGE AXIS OVER THE FORECAST AREA ON WEDNESDAY. EXPECT ANOTHER RELATIVELY MILD DAY WITH MOSTLY SUNNY SKIES AND ABOVE NORMAL TEMPERATURES. EXPECT HIGHS TO REACH JUST ABOVE FREEZING IN SOUTHWEST MINNESOTA AND ADJACENT AREAS...NUDGING INTO THE UPPER 30S IN NORTHWEST IOWA. THE WARMEST READINGS WILL BE FOUND IN SOUTH CENTRAL SOUTH DAKOTA WITH THE MID OR UPPER 40S IN AREAS WHERE MUCH OF THE SNOWPACK HAS MELTED. FOR THURSDAY...A CUT OFF LOW IS EXPECTED TO FORM IN THE SOUTHWEST PLAINS AND TRACK NORTHEAST INTO THE NORTHERN GREAT LAKES EARLY SATURDAY. SOME MODEL DIFFERENCES STILL EXIST...WITH THE ECMWF AND GEM STILL FOLLOWING A SLOWER AND SLIGHTLY MORE SOUTHERLY TRACK. ALL MODELS DO CLIP OUR SOUTHEASTERN COUNTIES AS THE SURFACE LOW TRACKS INTO IOWA THURSDAY EVENING. TEMPERATURES WILL BE PARTICULARLY TRICKY WITH READINGS EXPECTED TO RISE UP ABOVE FREEZING BY THE AFTERNOON. WITH VERY WARM LOW LEVELS...EXPECT PRECIPITATION TO BE ENTIRELY LIQUID FOR THIS SYSTEM...BUT WITH SURFACE READINGS POTENTIALLY BELOW FREEZING IN THE MORNING AND AGAIN THURSDAY NIGHT...FREEZING RAIN WILL ALSO BE POSSIBLE. BUT GIVEN THAT THESE TEMPERATURES WILL ONLY BE A DEGREE OR TWO BELOW FREEZING...ICE ACCUMULATION DOES NOT LOOK TO BE SIGNIFICANT. BUT WILL STILL CONTINUE TO MONITOR FOR ANY CHANGES IN THIS OUTLOOK. TEMPERATURES ON FRIDAY WILL LIKELY BE SOMEWHAT STEADY OR BEGIN TO FALL IN THE AFTERNOON AS COOLER TEMPERATURES BEGIN TO FILTER INTO THE AREA BEHIND THIS SYSTEM. THE BROAD POSITIVELY TILTED TROUGH DIGGING ACROSS THE SOUTHWEST PUSHES INTO THE WESTERN PLAINS FRIDAY EVENING...BRINGING THE NEXT POTENTIAL FOR WET WEATHER TO REGION FRIDAY NIGHT AND SATURDAY. AGAIN...THE ECMWF IS A BIT SLOWER AND SHOWS MORE OF A CLOSED UPPER LEVEL FEATURE. A SLIGHT CHANCE FOR SOME LIGHT SNOW OR FLURRIES WILL BE POSSIBLE AHEAD OF THE MAIN WAVE ON FRIDAY. THE DETAILS ARE STILL QUITE UNCERTAIN AT THIS POINT...BUT THE GFS APPEARS TO TAKE THE BEST DYNAMICS WEST AND NORTH OF THE FORECAST AREA...WHILE THE ECMWF HAS A BIT MORE ORGANIZATION WITH A DECENT BAND OF MID LEVEL FRONTOGENESIS MOVING THROUGH THE FORECAST AREA. WILL KEEP MENTION OF POPS AS A HIGH CHANCE FOR SOME LIGHT SNOWFALL FRIDAY NIGHT AND SATURDAY. PRELIMINARY AMOUNTS LOOK LIKE A FEW INCHES WOULD BE POSSIBLE ACROSS THE CWA. THE LOW EXITS THE AREA SATURDAY NIGHT WITH A STRONGER SHOT OF COLD AIR ADVECTION ARRIVING IN ITS WAKE. TEMPERATURES WILL BE MUCH COOLER FOR THE START OF NEXT WEEK WITH HIGHS MAINLY IN THE TEENS AND LOWS AROUND ZERO. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$
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AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1046 AM EST TUE JAN 8 2013 .SYNOPSIS... A WEDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION AND PREVAIL THROUGH WEDNESDAY...WHILE A COASTAL TROUGH STRENGTHENS OFFSHORE. A WEAK WARM FRONT WILL LIFT NORTH OF THE AREA THURSDAY AS A STORM SYSTEM PASSES WELL TO THE WEST. ATLANTIC HIGH PRESSURE WILL THEN PREVAIL INTO EARLY NEXT WEEK BEFORE A COLD FRONT APPROACHES FROM THE WEST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LATE THIS MORNING...SURFACE ANALYSIS SHOWS THE REGION SOLIDLY WITHIN THE LOW LEVEL RIDGE EXTENDING FROM THE 1032 MB HIGH LOCATED NEAR THE CHESAPEAKE. ALOFT...NEARLY ZONAL FLOW DOMINATES WITHIN THE SLIGHTLY ANTICYCLONICALLY CURVED SW FLOW. THE MAIN FORECAST ISSUES FOR TODAY REVOLVE AROUND THE EXPECTED INCREASING CLOUD COVER AND THE POTENTIAL FOR SHOWER DEVELOPMENT OVER THE COASTAL WATERS CLOSER TO THE OFFSHORE COASTAL TROUGH. CURRENT CLOUD COVER IS PRIMARILY COMPRISED OF MID/HIGH LEVEL CLOUDS...WITH SOME PATCHES OF LOWER OVERCAST SPREAD AROUND PORTIONS OF GA AND SC. I HAVE SLOWED THE PROGRESSION OF TOTALLY OVERCAST SKIES AND RAISED TEMPS A DEGREE OR SO BASED ON MORE SUNSHINE THAN ORIGINALLY THOUGHT. THIS STILL KEEPS HIGHS IN THE LOW 60S...EXCEPT FOR UPPER 50S FAR INLAND. BUT MODELS STILL SHOW CONSIDERABLE LOW LEVEL MOISTURE SO AT SOME POINT LATER TODAY AND INTO THE EVENING WE SHOULD BEGIN TO SEE A SOLID BLANKET OF STRATUS START TO DEVELOP. REGARDING THE COASTAL TROUGH...IT IS NOT VERY SHARPLY DEFINED AT THIS POINT AND ANY RESULTING SHOWER ACTIVITY IS QUITE WEAK AND LOCATED WELL OFFSHORE. RECENT RUNS OF THE RUC SHOW A BROADER COASTAL TROF THROUGH THE DAY WITH LESS COVERAGE OF SHOWERS WITHIN THE WEAKER LOW LEVEL CONVERGENCE. AS SUCH...I HAVE KEPT POPS IN THE SLIGHT CHANCE RANGE AND LIMITED THEM TO JUST THE COASTAL WATERS. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... TONIGHT...PRETTY MUCH THE SAME PATTERN WILL CONTINUE WITH INLAND HIGH PRESSURE AND OFFSHORE LOW PRESSURE. EXPECT MOST OF THE SHOWERS TO REMAIN OFFSHORE BUT COASTAL AREAS...ESPECIALLY ACROSS SOUTHEAST GEORGIA...LOOK TO HAVE THE BEST SHOT AT SEEING A FEW. WILL LIKELY SEE MORE IN THE WAY OF LOW CLOUDS AND SPRINKLES WITH SOME FOG AS WELL. LOWS SHOULD RANGE FROM THE MID TO UPPER 40S INLAND TO LOWER TO MID 50S ALONG THE COAST. WEDNESDAY AND WEDNESDAY NIGHT...THERE IS INCREASING CONFIDENCE THAT THE IN-SITU WEDGE OF HIGH PRESSURE WILL REMAIN ENTRENCHED OVER THE AREA AS THE PARENT SURFACE HIGH SHIFTS OFF THE MID-ATLANTIC COAST ALLOWING THE COASTAL TROUGH JUST OFFSHORE TO STRENGTHEN. ABUNDANT LOW LEVEL MOISTURE AND MODEST ISENTROPIC ASCENT WILL BE ENOUGH TO KEEP SKIES NEARLY OVERCAST WITH RATHER LOW CEILINGS EXPECTED. THE BEST FOCUS FOR ANY SHOWERS WILL MAINLY BE NEAR THE COASTAL TROUGH DUE TO ENHANCED LOW LEVEL CONVERGENCE...BUT ISENTROPIC ASCENT WILL SUPPORT ADDITIONAL LIGHT PRECIPITATION INLAND AS WELL WHICH WILL ONLY HELP TO REINFORCE THE WEDGE. THE FORECAST WILL INDICATE A CHANCE OF SHOWERS FOR MOST OF THE AREA BY WEDNESDAY AFTERNOON...THEN A SLIGHT CHANCE OF SHOWERS WEDNESDAY NIGHT. ALSO EXPECT AREAS OF FOG AND POSSIBLY DRIZZLE TO TO FORM WEDNESDAY NIGHT...AND THE FOG COULD BECOME DENSE AT TIMES. DESPITE MOST OF THE GUIDANCE BEING ON BOARD INDICATING LOW CEILINGS AND NORTH/NORTHEASTERLY WINDS ON WEDNESDAY...THEY ALL SHOW HIGHS REACHING INTO AT LEAST THE LOWER 70S WITH LOW LEVEL THICKNESS VALUES EVEN WARMER THAN THAT. THIS IS HARD TO BELIEVE GIVEN THIS SCENARIO...AND FEEL THE MODELS MAY NOT HAVE A GOOD HANDLE ON THE LOW LEVEL ENVIRONMENT. WILL THEREFORE CONTINUE TO FORECAST HIGHS ON WEDNESDAY WELL BELOW GUIDANCE...RANGING FROM THE MID 60S INLAND TO NEAR 70 ACROSS NORTH COASTAL GEORGIA AND NEAR THE ALTAMAHA RIVER. THURSDAY AND THURSDAY NIGHT...A COMBINATION OF A WARM FRONT AND COASTAL TROUGH WILL BEGIN TO LIFT NORTHWARD AS UPPER LEVEL RIDGING BUILDS OVER THE SOUTHEASTERN U.S. IN RESPONSE TO A STORM SYSTEM LIFTING NORTHEAST INTO THE MISSISSIPPI VALLEY. THIS WILL ALLOW FOR THE GRADUAL EROSION OF THE IN-SITU WEDGE. LOW CLOUDS AND FOG WILL LINGER INTO AT LEAST THE MORNING HOURS...BEFORE SOME PARTIAL CLEARING OCCURS LATER IN THE DAY. SEA FOG COULD FORM JUST OFF THE COAST AND POSSIBLY ADVECT INLAND AT JUST ABOUT ANY TIME. THERE COULD BE SOME ISOLATED TO SCATTERED SHOWERS AROUND...WITH THE GREATEST COVERAGE ACROSS SOUTHEAST SOUTH CAROLINA IN CLOSER PROXIMITY TO THE WARM FRONT MAINLY DURING THE DAY THURSDAY. THE BUILDING RIDGE AND LIFTING WARM FRONT WILL ALLOW TEMPERATURES TO SOAR TO HIGHS IN THE LOWER 70S ON THURSDAY...WITH ANOTHER WARM NIGHT EXPECTED THURSDAY NIGHT. FRIDAY...A PASSING SHORT WAVE DISTURBANCE WILL CAUSE THE UPPER RIDGE TO FLATTEN SOME IN THE MORNING...BUT A DEEP SOUTHERLY FLOW AROUND ATLANTIC HIGH PRESSURE WILL ALLOW FOR TEMPERATURES TO CONTINUE TO CLIMB. HIGHS ARE FORECAST TO BE IN THE MID TO UPPER 70S ACROSS MUCH OF THE AREA AWAY FROM THE COAST. SUFFICIENT LOW LEVEL MOISTURE AND THE PASSAGE OF THE SHORT WAVE COULD SUPPORT ISOLATED SHOWERS ACROSS THE AREA. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... MEDIUM RANGE GUIDANCE IS IN EXCELLENT AGREEMENT THROUGH THE WEEKEND INDICATING A STRONG UPPER LEVEL RIDGE OVER THE REGION...WHILE ATLANTIC HIGH PRESSURE PREVAILS AT THE SURFACE. STRONG SUBSIDENCE AND A LACK OF DEEP MOISTURE WILL KEEP CONDITIONS RAIN-FREE. THE BIGGER STORY WILL BE THE UNSEASONABLY WARM...IF NOT HOT FOR THIS TIME OF YEAR...TEMPERATURES. HIGHS OVER THE WEEKEND SHOULD BE WELL INTO THE UPPER 70S AWAY FROM THE COAST...WITH SOME 80 DEGREE READINGS CERTAINLY POSSIBLE. THESE HIGHS WILL BE APPROACHING RECORD TERRITORY. GUIDANCE BEGINS TO DIVERGE A BIT EARLY NEXT WEEK WITH RESPECT TO THE TIMING OF A COLD FRONT AS IT APPROACHES FROM THE WEST AND SLOWS AS IT ENCOUNTERS THE UPPER RIDGE. THE FORECAST WILL INDICATE A SLIGHT CHANCE OF SHOWERS ON MONDAY WITH PROBABILITIES INCREASING INTO THE CHANCE CATEGORY ON TUESDAY AS THE FRONT NEARS. TEMPERATURES SHOULD MODERATE SOME...BUT OVERALL REMAIN WELL ABOVE NORMAL. && .AVIATION /16Z TUESDAY THROUGH SATURDAY/... A WEDGE OF HIGH PRESSURE WILL BECOME BETTER ESTABLISHED TODAY AS A COASTAL TROUGH STRENGTHENS OFFSHORE. THIS WILL ALLOW ABUNDANT LOW LEVEL MOISTURE TO BECOME TRAPPED BENEATH AN INVERSION...RESULTING IN STRATUS THROUGH MOST OF THE FORECAST PERIOD. CEILINGS SHOULD BORDER THE VFR AND MVFR CATEGORIES FOR MOST OF THE AFTERNOON...BUT PREFER TO KEEP IT PREVAILING VFR UNTIL THERE IS A BETTER INDICATION TO WHEN LOWER CEILINGS WILL DEVELOP. THE POTENTIAL FOR LOWER CEILINGS WILL INCREASE THIS EVENING AS THE INVERSION LOWERS. WILL INDICATE MVFR CEILINGS AT BOTH TERMINALS AFTER ABOUT 23Z...WITH IFR CEILINGS AT KSAV AFTER 07Z. PATCHY FOG COULD ALSO REDUCE VISIBILITIES OVERNIGHT. EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS ARE LIKELY INTO THURSDAY. FOG COULD ALSO REDUCE VISIBILITIES TO MVFR OR LOWER LEVELS AT TIMES DURING THE LATE NIGHT/EARLY MORNING HOURS INTO THE WEEKEND. && .MARINE... TODAY AND TONIGHT...A TROUGH OF LOW PRESSURE IS EXPECTED TO REMAIN OVER THE LOCAL WATERS THROUGH TONIGHT WHICH WILL LEAD TO A VARYING WIND DIRECTION/SPEED FORECAST AS THE WESTERN SIDE OF THE TROUGH NEAR THE COAST WILL SEE ENHANCED NORTHEAST WINDS WHILE THE EASTERN SIDE SEES LIGHTER EASTERLY WINDS. DO NOT ANTICIPATE ANY HEADLINES OTHER THAN THE EXISTING ADVISORY FOR THE WATERS BEYOND 20 NM UNTIL EARLY AFTERNOON WHERE SEAS REMAIN ELEVATED IN THE NORTHEAST FLOW. MARINERS SHOULD ALSO BE ALERT FOR SOME FOG DEVELOPING LATE TONIGHT...ESPECIALLY ACROSS THE COOLER NEARSHORE WATERS ALONG THE GEORGIA COAST...AS A MORE HUMID AIRMASS SPREADS INTO THE AREA. WEDNESDAY THROUGH SUNDAY...A COASTAL TROUGH WILL PERSIST OVER OR NEAR THE WATERS ON WEDNESDAY...BEFORE LIFTING NORTH AS A WARM FRONT ON THURSDAY. THERE COULD BE SOME PINCHING OF THE GRADIENT EARLY WEDNESDAY KEEPING THE NORTHEAST FLOW SOMEWHAT ELEVATED...HOWEVER THE GRADIENT WILL WEAKEN AS THE FLOW VEERS TO THE SOUTHEAST THROUGH THURSDAY. A SOUTH-SOUTHWEST FLOW WILL THEN PREVAIL THROUGH THE WEEKEND DUE TO THE INFLUENCE OF ATLANTIC HIGH PRESSURE. WINDS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA THROUGH THE PERIOD...ALTHOUGH A FAVORABLE FETCH COULD BUILD SEAS TO 6 FT OVER A PORTION OF THE OUTER GEORGIA WATERS LATE THURSDAY AND FRIDAY. THERE IS A RISK OF SEA FOG OVER THE COOL NEARSHORE WATERS BEGINNING WEDNESDAY ACROSS THE GEORGIA NEARSHORE WATERS AND SPREADING NORTH LATE IN THE WEEK AND POSSIBLY INTO THE WEEKEND...AS A WARM AND MORE HUMID AIRMASS ADVECTS INTO THE AREA. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR AMZ374. && $$ NEAR TERM...BSH SHORT TERM...RJB/JAQ LONG TERM...JAQ AVIATION...JAQ MARINE...RJB/JAQ
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
535 AM CST TUE JAN 8 2013 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... In the short term, concerns are focused on temperatures along with rainfall potential Wednesday night into Thursday. Early this morning, a large upper level low continued to spin over northern Mexico as a progressive upper trough crosses the Northern Plains. Due to an enhanced area of cirrus moving across the region, temperatures have remained in the 30s in most locations. Today: Upper troughing in the Northern Plains will establish weak surface troughing across portions of east central Kansas through northwestern Missouri. Winds ahead of this surface trough will again become breezy by afternoon, with abnormally warm 950:850 temperatures supporting temperatures into the 50s in many areas. Again, have followed short term RAP guidance for temperatures this afternoon which did an excellent job on Monday. The warmest temperatures may pool just ahead of this surface trough where readings could spike into the middle 50s. Tonight: The weak surface trough will move into the region washing out as it does so. A bit less cirrus may be possible given the northwesterly upper level flow. The resultant temperatures will fall into the upper 20s in most locations. Wednesday: The upper level low over northern Mexico will finally become dislodged as troughing enters the Pacific Northwest. Locally, an elongated west to east ridge of high pressure will remain over the area throughout the daytime hours, keeping winds light and variable. Temperatures, given the weak boundary and low level flow, will not be quite as warm as on Tuesday but should still climb near 50. Wednesday night: The upper level low will quickly begin to surge north by Wednesday evening with strong low-level moisture advection headed into the area. Showers and even embedded thunderstorms will overspread the area through the overnight hours. Models in reasonable agreement (less the NAM) that rain will reach the Interstate 70 corridor by midnight and northern Missouri by daybreak. Thursday: Tricky forecast as models indicate the deep upper low will lift across the CWA during the daytime hours. Rain should quickly lift northward in the morning, replaced with low cloud cover and periods of showers/drizzle. Temperatures will be rather difficult and highly dependent on the track of surface low pressure and surge of warm air ahead of the surface low. Model guidance suggests a weak surface low tracking north along with the upper low through eastern Kansas by Thursday afternoon. NAM is the most aggressive bringing near 60 degree readings into the CWA, but it is also the deepest and most progressive solution of all guidance. Prefer the weaker solutions of the GFS/SREF which still bring low 50s by the late afternoon hours. Dux Medium Range (Friday through Monday)... The medium range should start out very warm especially for the climatologically coldest week of the year for Kansas City (January 10-17). With 850mb temps between 12C-14C, if we can mix out enough, temperatures could easily range into the mid 50s to mid 60s. However, those warm temperatures will be short-lived as a cold front is forced into the forecast area Friday night in association with a broad and deep upper level trough that will be traversing the Rockies. This frontal passage looks to be dry as models are in good agreement that the best moisture transport is south and east of the forecast area. As such have lowered chance POPs inherited by the initialization to silent slight chance POPs for Saturday. The main effect of this cold front will be the marked change in temperatures. High temperatures across the CWA Saturday will experience a 20 degree range from near 30 across northern Missouri where cold air advection will be ongoing by day break...to near 50 across central Missouri where cold air doesn`t begin to advect in until later in the day. The upper level trough moves through the area on Sunday as high pressure builds in at the surface with highs in the mid 20s to lower 30s. Surface high pressure strengths over the area on Monday and with abundant sunshine highs will return to near normal for the coldest climatological week of the year with highs in the 30s. 73 && .AVIATION... For the 12Z TAFs...conditions will remain VFR through the TAF period with just cirrus expected through the day before clearing skies tonight. Winds out of the south this morning around 10kts will veer to the southwest this afternoon. A weak surface trough will move through the terminals tonight veering winds to the west at MCI while winds and MKC and STJ become light and variable. 73 && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1016 AM EST TUE JAN 8 2013 .SYNOPSIS... HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH WEDNESDAY. A BACKDOOR COLD FRONT WILL PUSH INTO THE REGION THURSDAY... THEN RETURN NORTH AS A WARM FRONT LATE FRIDAY. && .NEAR TERM /THROUGH WEDNESDAY/... AS OF 305 AM TUESDAY... REST OF TODAY: SOUTHWEST FLOW ALOFT WILL PREVAIL TODAY...DOWNSTREAM OF A POTENT UPPER LEVEL LOW MEANDERING EASTWARD ACROSS NORTHERN MEXICO. SMALL AMPLITUDE DISTURBANCES WILL PROGRESS INTO THE CAROLINAS VIA SW FLOW ALOFT THIS AFTERNOON...THOUGH NO APPRECIABLE DPVA IS ANTICIPATED. A RELATIVELY WEAK 925-850 MB RETURN FLOW IS IN PLACE TODAY...ON THE WESTERN PERIPHERY OF A LOW-LEVEL RIDGE CENTERED JUST OFFSHORE IN THE ATLANTIC. AT THE SURFACE...LITTLE OR NO ADVECTION WILL OCCUR IN THE PRESENCE OF A SFC RIDGE AXIS EXTENDING NORTHEAST FROM UPSTATE SC TO SOUTHEAST VA. BROKEN TO OVERCAST LOW-LEVEL CLOUD COVER THIS MORNING MAY PERSIST INTO THE AFTERNOON IN ASSOC/W LOW-LEVEL WARM ADVECTION...ESP OVER THE NORTHERN PIEDMONT AND NE COASTAL PLAIN. UNCERTAINTY IN CLOUD COVER AND RESULTING TEMPERATURES ARE THE PRIMARY FCST PROBLEM. GIVEN CURRENT OBS/SAT IMAGERY AND REASONABLE FORCING FOR CLOUD COVER TO PERSIST THROUGH MUCH OF DIURNAL HEATING...HAVE OPTED TO LOWER HIGH TEMPS A FEW DEGREES...RANGING FROM 50-54F (WARMEST FAR S/SE AND COOLEST N/NE). THOUGH LOW-LEVEL FORCING SHOULD BE SUFFICIENT TO SUPPORT BROKEN TO OVERCAST CLOUD COVER...OVERALL FORCING AND MOISTURE WILL BE INSUFFICIENT TO SUPPORT PRECIPITATION. -VINCENT TONIGHT... CONTINUATION OF THE RETURN FLOW AROUND OF THE ELONGATING SURFACE RIDGE AXIS WILL LEAD TO STRATUS AGAIN OVERNIGHT. FORECAST SOUNDINGS ARE SUPPORTED BY HIGH SREF PROBABILITIES OF LOW CEILINGS OVER THE WESTERN PIEDMONT. HIGH CLOUDS SHOULD ALSO BE ON THE INCREASE AS MOISTURE STREAMS IN FROM THE SOUTHWEST AHEAD OF AN UPPER LOW MOVING SLOWLY ACROSS THE TX/MEXICO BORDER. MOSTLY CLOUDY SKIES SHOULD LIMIT ANY FOG POTENTIAL...BUT WITH DEWPOINTS CREEPING UP INTO THE LOWER 40S AND WEAK WINDS WITHIN THE SURFACE RIDGE AXIS...THERE COULD BE SOME PATCHY FOG IN THE SOUTH AND EAST LATE TONIGHT. LOWS 37-42. WEDNESDAY... THE AIRMASS OVER CENTRAL NC WILL CONTINUE TO MOISTEN WEDNESDAY AS HIGH PRESSURE LINGERS OFF THE COAST AND RETURN FLOW PERSISTS. AN UNSEASONABLY STRONG SUBTROPICAL RIDGE WILL HOLD OVER THE SOUTHEAST US...WHILE ONE SHORTWAVE CROSSES THE GREAT LAKES REGION AND THE AFOREMENTIONED UPPER LOW OVER TX BEGINS TO LIFT NORTH THROUGH THE SOUTHERN PLAINS. MODELS GENERATE SOME VERY LIGHT QPF LATE IN THE DAY ACROSS THE SOUTHERN CWA...BUT THIS APPEARS TO BE OVERDONE GIVEN THE LACK OF FORCING. WILL MAINTAIN A DRY FORECAST FOR WEDNESDAY. LOW LEVEL THICKNESSES APPROACH 1370M BY WEDNESDAY AFTERNOON..BUT AS PW VALUES RISE TO NEAR ONE INCH... THERE SHOULD AGAIN BE SOME IMPACT OF CLOUD COVER ON HEATING. HIGHS 61-66. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 300 AM TUESDAY... A HYBRID COLD AIR DAMMING EVENT LIKELY LATE THURSDAY INTO FRIDAY... THE EVOLVING PATTERN CONSISTING OF A DEEP WEST-CENTRAL U.S. TROUGH AND STRONGLY RISING UPPER HEIGHTS FROM THE CARIBBEAN THROUGH THE SOUTHEAST U.S. LATE WEEK INTO THE WEEKEND WILL EVENTUALLY MEAN A WARM AND MOSTLY DRY PERIOD FOR OUR REGION THIS WEEKEND. BEFORE THAT OCCURS... A HYBRID CAD EVENT IS EXPECTED TO DEVELOP OVER THE PIEDMONT DAMMING REGION THURSDAY AND LAST INTO FRIDAY. THE WARMING ASSOCIATED WITH RISING HEIGHTS ALOFT WILL INITIALLY BE OFFSET BY THE STRONG (1035+ MB) SURFACE HIGH THAT IS EXPECTED TO BUILD EAST FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST THURSDAY INTO EARLY FRIDAY. THE STRENGTH AND POSITION OF THIS HIGH PRESSURE IS VERY FAVORABLE FOR CAD DEEP INTO OUR REGION. THE HIGH IS FORECAST TO BE PROGRESSIVE AS THE MID/UPPER FLOW OVER THE NE US BECOMES CONFLUENT BY THE WEEKEND... MAKING THIS A HYBRID CAD EVENT... AND ONE THAT WILL ERODE A BIT MORE QUICKLY THAN CLASSICAL CAD EPISODES. INITIALLY ON THURSDAY... THE HIGH IS EXPECTED TO BUILD SOUTH... DOWN THE EASTERN SEABOARD... WHEN THE SOUTHERN PLAINS STORM SYSTEM IS FORECAST TO TRACK NE THROUGH THE OHIO VALLEY THU NIGHT. WARM MOIST AIR IS EXPECTED TO OVERRUN THE COOL STABLE LAYER EAST OF THE MOUNTAINS THU NIGHT AND FRIDAY... WITH AREAS OF RAIN DEVELOPING/OVERSPREADING THE REGION. THIS WILL ALLOW THE CAD EVENT TO SHAPE UP THURSDAY NIGHT INTO FRIDAY. THE EVENTUAL DEPTH AND DURATION OF THE CAD SHOULD LARGELY BE DRIVEN BY THE AMOUNT OF QPF THOSE PERIODS INTO THE COOL STABLE AIR... LOCKING THE CAD IN PLACE. THE CURRENT FAVORED BLEND OF THE LATEST GFS/EC OPERATIONAL MODELS AND EC ENSEMBLES INDICATE THE QPF TO REACH THE CRITICAL 0.12 TO 0.25 THRESHOLD IN THE PIEDMONT DAMMING REGION... SUFFICIENT TO LOCK IN THE CAD THURSDAY NIGHT INTO EARLY FRIDAY. IF THIS IS REALIZED... THIS WILL DELAY THE THE WARM FRONT FROM SURGING THROUGH CENTRAL NC ON FRIDAY MORNING. IT WOULD TAKE MUCH OF THE DAY FOR THE DAMMING (PARTICULARLY THE RESIDUAL AFFECTS - LOWS CLOUDS/FOG/DRIZZLE) TO ERODE. CURRENT THINKING IS THAT THE PIEDMONT TRIAD REGION MAY VERY WELL HAVE CAD AFFECTS INTO SAT MORNING. SENSIBLE WEATHER... PARTLY CLOUDY WEDNESDAY NIGHT WITH LOWS IN THE UPPER 30S TO MID 40S. THURSDAY... INCREASING CLOUDS NE... MOSTLY CLOUDY TO CLOUDY WEST. WINDS BECOMING ENE. HIGHS IN THE 50S TO LOWER 60S SE. THURSDAY NIGHT AND EARLY FRIDAY... RAIN LIKELY NW AND A CHANCE SE. COOL IN THE DAMMING REGION. LOWS IN THE 40S. LINGERING LOW CLOUDS AND LIGHT RAIN/DRIZZLE FRIDAY IN THE DAMMING REGION. BECOMING MOSTLY CLOUDY SE/WARMER. HIGHS 55 NW TO UPPER 60S SE. PARTLY CLOUDY TO CLOUDY FRIDAY NIGHT. WARMER. LOWS 45-55. AREAS OF FOG/LOW CLOUDS AGAIN LIKELY NW. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 300 TUESDAY... THE LATEST MODELS SUPPORT THE SLOWER TIMING OF THE COLD FRONT BY EARLY NEXT WEEK. THIS WILL ENSURE A WEEKEND OF WARM DRY WEATHER WITH TEMPS 20 TO 30 DEGREES ABOVE NORMAL. WE WILL HOLD OFF MENTION OF ANY SHOWERS UNTIL SUNDAY NIGHT OR MONDAY. BECOMING PARTLY CLOUDY SATURDAY. BREEZY AND WARMER. HIGHS IN THE UPPER 60S TO MID 70S. LOWS SAT NIGHT IN THE 50S (AVERAGE HIGHS ARE 48-53). SUNDAY... PARTLY SUNNY. HIGHS LOWER TO MID 70S. MONDAY... MOSTLY CLOUDY WITH A CHANCE OF SHOWERS. HIGHS IN THE 60S TO LOWER 70S SE. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 645 AM TUESDAY... WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE CAROLINAS. STRATOCU HAS SPREAD FROM SC NORTH ACROSS ALMOST ALL OF CENTRAL NC. CEILINGS GENERALLY VARY FROM 5000FT NORTH TO 3000FT SOUTH. BASED ON SATELLITE TRENDS AND HRRR MODEL MOISTURE FIELDS...MVFR CEILINGS ARE MOSTLY LIKELY IN THE NEXT 3-6 HOURS AT KFAY/KGSO/KINT. MVFR CEILINGS CANNOT BE RULED OUT AT KRDU AND/OR KRWI..BUT CONFIDENCE IS MUCH LOWER AT THESE SITES. WHILE SOME IMPROVEMENT IS FORECAST THIS AFTERNOON...THIS MOISTURE IS TRAPPED BENEATH A STRONG SUBSIDENCE INVERSION LOCATED NEAR 5000FT...SO CEILINGS ARE LIKELY TO REMAIN NEAR MVFR LEVELS THROUGHOUT THE DAY. TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT). OUTLOOK... AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT APPROACHES FROM THE SOUTH-SOUTHWEST. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...VINCENT/SMITH SHORT TERM...BADGETT LONG TERM...BADGETT AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
952 AM EST TUE JAN 8 2013 .SYNOPSIS... A COASTAL TROUGH JUST OFFSHORE WILL WEAKEN TONIGHT AS A RIDGE OF HIGH PRESSURE TO OUR NORTH EXPANDS. LOW PRESSURE MOVING NORTHEAST OUT OF THE PLAIN STATES WILL BRING A WARM FRONT ACROSS THE EASTERN CAROLINAS ON FRIDAY. HIGH PRESSURE WILL BRING AN END TO THE UNSETTLED WEATHER WITH WARM AND DRY CONDITIONS FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 930 AM TUESDAY...HIGH PRESSURE ALONG THE MID-ATLANTIC COAST AND A WEAK COASTAL TROUGH ROUGHLY 30-40 MILES OFFSHORE ARE PRODUCING A COOL NORTHEAST WIND ACROSS THE EASTERN CAROLINAS. SATELLITE SHOWS LOW AND MID-LEVEL CLOUD COVER ASSOCIATED WITH MOIST ATLANTIC AIR OVERRIDING THE SHALLOW COLD AIRMASS INLAND. THERE ARE SOME SIZABLE HOLES IN THESE CLOUD DECKS MAINLY ACROSS EASTERN SOUTH CAROLINA...AND THIS IS COMPLICATING OUR FORECAST FOR TODAY. CONFIDENCE WITH RESPECT TO OUR HIGH TEMPERATURE FORECAST REMAINS RATHER LOW. THE BULK OF MODEL GUIDANCE INCLUDING THE LATEST RUC AND HRRR MODELS ARE SIGNIFICANTLY WARMER THAN OUR FORECAST TODAY. IN FACT...BLENDING THE RUC AND HRRR GIVES LOW TO MID 60S ACROSS MOST OF OUR AREA WITH 50S ONLY HANGING AROUND NEAR THE BEACHES AND AROUND LUMBERTON. THIS MAY BE UNREASONABLY WARM GIVEN THE WEDGE-LIKE CONFIGURATION TO LOW-LEVEL WINDS...MOSTLY CLOUDY SKIES...AND THE COASTAL TROUGH REMAINING OFFSHORE. THE ONLY AREA WHERE LOW 60S ARE CURRENTLY FORECAST IS IN THE NARROW ZONE OF EASTERN SOUTH CAROLINA EAST OF I-95 BUT AWAY FROM THE BEACHES INCLUDING CONWAY...SOUTHERN MARION COUNTY...INLAND GEORGETOWN COUNTY AND WILLIAMSBURG COUNTY. ELSEWHERE...MID 50S SHOULD PREDOMINATE. RADAR IMAGERY SHOWS A PATCH OF LIGHT RAIN SITUATED IN THE ZONE OF STRONGEST ISENTROPIC LIFT NEAR AND JUST EAST OF BALD HEAD ISLAND. THIS SHOULD SHIFT NORTH OVER THE NEXT FEW HOURS BUT WILL LARGELY DISSIPATE THIS AFTERNOON. OTHERWISE DRY CONDITIONS SHOULD CONTINUE. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 330 AM TUESDAY...DEVELOPING LOW PRESSURE SYSTEM OVER THE TEXAS GULF COAST WILL TRACK NORTH TOWARD THE GREAT LAKES THROUGH THE PERIOD. AS THE MID TO UPPER LOW DEEPENS OVER THE MID WEST...THE RIDGE BECOMES MORE AMPLIFIED UP THROUGH THE SOUTHEAST COAST. MODELS STILL SHOWING H5 HEIGHTS REACHING UP NEAR 588 DEM BY THURS MORNING. WAA WILL BRING 850 TEMPS UP CLOSE TO 12C BY THURS BUT A SHALLOW COOLER ON SHORE FLOW WILL EXIST AT THE SURFACE THROUGH MID WEEK. INTERESTING SCENARIO AS COASTAL TROUGH WILL EXIST UP THROUGH THE COASTAL CAROLINAS WITH COOLER NE FLOW INLAND AND SOUTHEAST FLOW OFF SHORE REACHING THE COAST. THIS COASTAL TROUGH WILL PROVIDE FOCUS FOR CLOUDS AND SOME PCP MAINLY TO THE SOUTH THROUGH WEDNESDAY WHILE HIGH PRESSURE TO THE NORTH WILL PUSH A BACKDOOR COLD FRONT INTO NORTH CAROLINA OVERNIGHT WED. THE GFS SHOWS THIS BOUNDARY MAKING IT INTO LOCAL CWA BY THURS MORNING BUT THEN RETURNING NORTH AS WARM FRONT. THIS MAY REINFORCE SHALLOW COOLER AIR BRIEFLY AT THE SURFACE WHILE WINDS ALOFT INCREASE OUT OF THE SOUTH AS STORM SYSTEM OVER THE MID WEST STRENGTHENS. EXPECT DECENT AMOUNT OF LOW LEVEL CLOUDS THROUGH WED BUT SUBSIDENCE AND DRY AIR THROUGH THE MID LEVELS SHOULD PREVENT MUCH IN THE WAY OF PCP UNTIL LATE WED INTO THURS WHEN COASTAL TROUGH/WARM FRONT MAKES PROGRESS INLAND AND NORTH. WILL KEEP BEST CHC OF MEASURABLE PCP AND HIGHEST QPF DURING THURS. SHOULD SEE AN END TO MOST OF THE PCP HEADING INTO THURS EVENING AS BEST LIFT SHIFTS NORTH OF AREA AS WARM FRONT GETS PULLED NORTH AS STORM SYSTEM MOVES UP INTO THE GREAT LAKES. OVERALL WILL SEE CLOUDS THROUGH MOST OF THE PERIOD AND BEST CHC OF PCP OVERNIGHT WED INTO EARLY THURS. TEMPS MAY BE A BIT TRICKY WITH CLOUDS AND PCP BEING OFFSET BY WAA AND RIDGE BUILDING ALOFT WITH H5 HEIGHT INCREASES. THEN THE BACKDOOR COLD FRONT MAY PROVIDE ANOTHER BURST OF VERY SHALLOW COOL AIR FOR THURS MORNING BEFORE WARM FRONT MOVES NORTH OF AREA. EXPECT MAX TEMPS UP INTO THE 60S AND LOWS REMAINING CLOSE TO 50 OR ABOVE. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 3 AM TUESDAY...STRONG RIDGE BUILDING UP FROM THE BAHAMAS UP THROUGH THE SOUTHEAST WILL BECOME TEMPORARILY DISRUPTED EARLY FRIDAY AS IT TRACKS ACROSS THE CAROLINAS. ONCE THIS SHORTWAVE CLEARS THE COAST IT WILL PUSH A COLD FRONT FARTHER EAST AWAY FROM AREA ALLOWING HIGH PRESSURE TO DOMINATE THROUGH THE WEEKEND INTO EARLY NEXT WEEK. THE RIDGE AXIS WILL RIDE UP RIGHT ALONG THE SOUTHEAST COAST WITH CENTER OF THE SURFACE HIGH DISPLACED TO THE EAST. THIS WILL PRODUCE A DEEP W-SW RETURN FLOW THROUGH MOST OF THE PERIOD WITH PLENTY OF SUBSIDENCE AND DRY AIR THROUGH THE MID LEVELS OF THE ATMOSPHERE. SOME LOW LEVEL MOISTURE SHOULD PRODUCE SOME CLOUDS THROUGH THE PERIOD. H5 HEIGHTS REMAIN AROUND 585 DEM AS RIDGE HOLDS ON TIGHT THROUGH THE WEEKEND. 850 TEMPS HOLD UP TO 13 TO 14 C IN WAA INTO EARLY NEXT WEEK. OVERALL EXPECT TEMPS TO BE WELL ABOVE NORMAL WITH AFTERNOON HIGHS INTO THE 70S AND OVERNIGHT LOWS CLOSE TO NORMAL HIGHS FOR THIS TIME OF YEAR...IN THE MID 50S. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 12Z...VFR/MVFR CIGS ACROSS THE AREA THIS MORNING AS SATELLITE IMAGERY DEPICTS PLENTY OF LOW-LEVEL CLOUD COVER ASSOCIATED WITH A COASTAL TROUGH. MOIST RETURN FLOW AROUND THE HIGH PRESSURE CENTERED OFFSHORE WILL KEEP THE LOW CLOUDS AROUND THROUGH THIS TAF PERIOD. IT APPEARS THAT LOW VFR CIGS WILL BE MOST PREVALENT ACROSS THE AREA TODAY...ALTHOUGH SOME MVFR CIGS ARE POSSIBLE AS WELL. COULD SEE SOME ISOLATED DRIZZLE ALONG THE COAST...BUT DECIDED IT WAS NOT WORTH MENTIONING IN TAFS. EXPECT EAST WINDS AOB 8 KNOTS TODAY...BECOMING LIGHT/CALM OVERNIGHT. MODEL SOUNDINGS AND GUIDANCE BOTH SUPPORT A FOG/STRATUS EVENT OVERNIGHT WITH ABUNDANT LOW-LEVEL MOISTURE IN PLACE ACROSS THE REGION. INCLUDED MVFR CIGS/VSBYS AFTER MIDNIGHT AT ALL TERMINALS...AND IFR CONDITIONS COULD DEVELOP TOWARDS THE END OF THE TAF PERIOD. EXTENDED OUTLOOK...POSSIBLE MVFR/IFR CIGS WEDNESDAY AND THURSDAY. SLIGHT CHANCE OF SHOWERS LATE WEDNESDAY INTO THURSDAY. VFR DEVELOPING FRIDAY AND PERSISTING THROUGH SATURDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 930 AM TUESDAY...BASED ON DATA FROM THE FRYING PAN SHOALS BUOY SHOWING A SOUTHEAST WIND AND 66 DEGREE AIR TEMPERATURES...THE COASTAL TROUGH LIES JUST TO THEIR WEST. ALL OTHER BUOY AND COASTAL LOCATIONS HAVE MUCH COLDER AIR TEMPERATURES WITH NORTH TO NORTHEAST WINDS. MODEL CONSENSUS IS THIS TROUGH SHOULD WEAKEN THIS AFTERNOON AND ESPECIALLY TONIGHT AS THE HIGH ALONG THE MID-ATLANTIC COAST NUDGES BACK TO THE SOUTH. RADAR SHOWS SOME PATCHY LIGHT RAIN JUST EAST OF CAPE FEAR CURRENTLY. THIS PRECIPITATION SHOULD MOVE SLOWLY NORTH THIS MORNING POTENTIALLY AFFECTING THE COASTAL WATERS NEAR CAROLINA BEACH BEFORE DISSIPATING THIS AFTERNOON. THE SURGE OF STRONG NORTH-NORTHEAST WINDS EARLIER THIS MORNING IS DIMINISHING AND BY THIS AFTERNOON WIND SPEEDS SHOULD REMAIN BELOW 15 KNOTS. SEAS HAVE ALSO STARTED DIMINISHING WITH 5 FT SEAS AT THE FRYING PAN SHOALS BUOY AND 4 FT AT THE NEARSHORE WRIGHTSVILLE BEACH BUOY. THE EXERCISE CAUTION HEADLINE WILL CONTINUE FOR THE NC WATERS THROUGH 11 AM. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...COASTAL TROUGH ON WED BECOMES DAMPENED AS HIGH PRESSURE PUSHES A BACK DOOR COLD FRONT SOUTH. SHOULD SEE LIGHT E-SE FLOW THROUGH WED 10 KTS OR LESS. FLOW MAY SHIFT AROUND TO THE NE BRIEFLY EARLY THURS AS WEAK BACKDOOR FRONT MOVES INTO AREA BUT THIS WILL MOVE BACK NORTH AS WARM FRONT ON THURSDAY WITH AN INCREASING SOUTHERLY FLOW DEVELOPING THURS NIGHT. SEAS WILL BASICALLY REMAIN 3 FT OR LESS THROUGH THURS MORNING AND THEN WILL RISE UP TO 3 TO 5 FT IN INCREASING SOUTHERLY PUSH LATE THURS INTO FRI. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3 AM TUESDAY...SOUTHERLY FLOW AROUND 15 KTS WILL VEER TO THE SOUTHWEST AND LIGHTEN THROUGH THE FIRST HALF OF THE WEEKEND AS HIGH PRESSURE OVER THE LOCAL WATERS SHIFTS SOUTH AND WEST. OVERALL GRADIENT WILL RELAX THROUGH SATURDAY. EXPECT WINDS TO LIGHTEN TO 10 KTS OR LESS BY LATE SAT WITH SEAS DIMINISHING FROM 3-5 FEET ON FRI DOWN TO 2 TO 3 FT BY SAT NIGHT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...RGZ AVIATION...BJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
645 AM EST TUE JAN 8 2013 .SYNOPSIS... HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH WEDNESDAY. A BACKDOOR COLD FRONT WILL PUSH INTO THE REGION THURSDAY... THEN RETURN NORTH AS A WARM FRONT LATE FRIDAY. && .NEAR TERM /THROUGH WEDNESDAY/... AS OF 305 AM TUESDAY... TODAY... A 1030MB SURFACE HIGH CENTERED OVER THE VA TIDEWATER AREA EXTENDS SOUTHWEST ACROSS CENTRAL NC THIS MORNING. ALOFT...A WEAK DISTURBANCES WITHIN THE BROAD SUBTROPICAL RIDGE IS MOVING OVER THE CWA...WITH THE ASSOCIATED CIRRUS CURRENTLY EXITING THE NORTHERN COASTAL PLAIN. BENEATH A STRONG AND DRY SUBSIDENCE INVERSION AT 900MB...INCREASINGLY VEERED LOW LEVEL FLOW IS BEGINNING TO ADVECT MOISTURE INLAND. IR IMAGERY SHOWS STRATUS EXPANDING FROM COASTAL CAROLINA NORTHWESTWARD INTO THE SOUTHERN COASTAL PLAIN AND SANDHILLS. THE HRRR MOISTURE FIELDS...WHICH APPEAR TO HAVE A GOOD HANDLE ON THIS CLOUD COVER...SHOW MOISTURE SPREADING NORTH THROUGH THE PIEDMONT THIS MORNING. IF THE CLOUD COVER IS AS THICK AND WIDESPREAD AS THE NAM AND RAP FORECAST SOUNDINGS SHOW....HIGHS WILL BE A GOOD 5-7 DEGREES BELOW FULL SUN THICKNESS VALUES TODAY. PREFER THE COOLER MET MOS BASED ON CURRENT TRENDS...51-58 WEST TO EAST. OTHERWISE..NO SENSIBLE WEATHER IMPACTS TODAY AS MOISTURE IS MUCH TOO SHALLOW AND THE MID LEVELS TOO DRY FOR ANY PRECIP. TONIGHT... CONTINUATION OF THE RETURN FLOW AROUND OF THE ELONGATING SURFACE RIDGE AXIS WILL LEAD TO STRATUS AGAIN OVERNIGHT. FORECAST SOUNDINGS ARE SUPPORTED BY HIGH SREF PROBABILITIES OF LOW CEILINGS OVER THE WESTERN PIEDMONT. HIGH CLOUDS SHOULD ALSO BE ON THE INCREASE AS MOISTURE STREAMS IN FROM THE SOUTHWEST AHEAD OF AN UPPER LOW MOVING SLOWLY ACROSS THE TX/MEXICO BORDER. MOSTLY CLOUDY SKIES SHOULD LIMIT ANY FOG POTENTIAL...BUT WITH DEWPOINTS CREEPING UP INTO THE LOWER 40S AND WEAK WINDS WITHIN THE SURFACE RIDGE AXIS...THERE COULD BE SOME PATCHY FOG IN THE SOUTH AND EAST LATE TONIGHT. LOWS 37-42. WEDNESDAY... THE AIRMASS OVER CENTRAL NC WILL CONTINUE TO MOISTEN WEDNESDAY AS HIGH PRESSURE LINGERS OFF THE COAST AND RETURN FLOW PERSISTS. AN UNSEASONABLY STRONG SUBTROPICAL RIDGE WILL HOLD OVER THE SOUTHEAST US...WHILE ONE SHORTWAVE CROSSES THE GREAT LAKES REGION AND THE AFOREMENTIONED UPPER LOW OVER TX BEGINS TO LIFT NORTH THROUGH THE SOUTHERN PLAINS. MODELS GENERATE SOME VERY LIGHT QPF LATE IN THE DAY ACROSS THE SOUTHERN CWA...BUT THIS APPEARS TO BE OVERDONE GIVEN THE LACK OF FORCING. WILL MAINTAIN A DRY FORECAST FOR WEDNESDAY. LOW LEVEL THICKNESSES APPROACH 1370M BY WEDNESDAY AFTERNOON..BUT AS PW VALUES RISE TO NEAR ONE INCH... THERE SHOULD AGAIN BE SOME IMPACT OF CLOUD COVER ON HEATING. HIGHS 61-66. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 300 AM TUESDAY... A HYBRID COLD AIR DAMMING EVENT LIKELY LATE THURSDAY INTO FRIDAY... THE EVOLVING PATTERN CONSISTING OF A DEEP WEST-CENTRAL U.S. TROUGH AND STRONGLY RISING UPPER HEIGHTS FROM THE CARIBBEAN THROUGH THE SOUTHEAST U.S. LATE WEEK INTO THE WEEKEND WILL EVENTUALLY MEAN A WARM AND MOSTLY DRY PERIOD FOR OUR REGION THIS WEEKEND. BEFORE THAT OCCURS... A HYBRID CAD EVENT IS EXPECTED TO DEVELOP OVER THE PIEDMONT DAMMING REGION THURSDAY AND LAST INTO FRIDAY. THE WARMING ASSOCIATED WITH RISING HEIGHTS ALOFT WILL INITIALLY BE OFFSET BY THE STRONG (1035+ MB) SURFACE HIGH THAT IS EXPECTED TO BUILD EAST FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST THURSDAY INTO EARLY FRIDAY. THE STRENGTH AND POSITION OF THIS HIGH PRESSURE IS VERY FAVORABLE FOR CAD DEEP INTO OUR REGION. THE HIGH IS FORECAST TO BE PROGRESSIVE AS THE MID/UPPER FLOW OVER THE NE US BECOMES CONFLUENT BY THE WEEKEND... MAKING THIS A HYBRID CAD EVENT... AND ONE THAT WILL ERODE A BIT MORE QUICKLY THAN CLASSICAL CAD EPISODES. INITIALLY ON THURSDAY... THE HIGH IS EXPECTED TO BUILD SOUTH... DOWN THE EASTERN SEABOARD... WHEN THE SOUTHERN PLAINS STORM SYSTEM IS FORECAST TO TRACK NE THROUGH THE OHIO VALLEY THU NIGHT. WARM MOIST AIR IS EXPECTED TO OVERRUN THE COOL STABLE LAYER EAST OF THE MOUNTAINS THU NIGHT AND FRIDAY... WITH AREAS OF RAIN DEVELOPING/OVERSPREADING THE REGION. THIS WILL ALLOW THE CAD EVENT TO SHAPE UP THURSDAY NIGHT INTO FRIDAY. THE EVENTUAL DEPTH AND DURATION OF THE CAD SHOULD LARGELY BE DRIVEN BY THE AMOUNT OF QPF THOSE PERIODS INTO THE COOL STABLE AIR... LOCKING THE CAD IN PLACE. THE CURRENT FAVORED BLEND OF THE LATEST GFS/EC OPERATIONAL MODELS AND EC ENSEMBLES INDICATE THE QPF TO REACH THE CRITICAL 0.12 TO 0.25 THRESHOLD IN THE PIEDMONT DAMMING REGION... SUFFICIENT TO LOCK IN THE CAD THURSDAY NIGHT INTO EARLY FRIDAY. IF THIS IS REALIZED... THIS WILL DELAY THE THE WARM FRONT FROM SURGING THROUGH CENTRAL NC ON FRIDAY MORNING. IT WOULD TAKE MUCH OF THE DAY FOR THE DAMMING (PARTICULARLY THE RESIDUAL AFFECTS - LOWS CLOUDS/FOG/DRIZZLE) TO ERODE. CURRENT THINKING IS THAT THE PIEDMONT TRIAD REGION MAY VERY WELL HAVE CAD AFFECTS INTO SAT MORNING. SENSIBLE WEATHER... PARTLY CLOUDY WEDNESDAY NIGHT WITH LOWS IN THE UPPER 30S TO MID 40S. THURSDAY... INCREASING CLOUDS NE... MOSTLY CLOUDY TO CLOUDY WEST. WINDS BECOMING ENE. HIGHS IN THE 50S TO LOWER 60S SE. THURSDAY NIGHT AND EARLY FRIDAY... RAIN LIKELY NW AND A CHANCE SE. COOL IN THE DAMMING REGION. LOWS IN THE 40S. LINGERING LOW CLOUDS AND LIGHT RAIN/DRIZZLE FRIDAY IN THE DAMMING REGION. BECOMING MOSTLY CLOUDY SE/WARMER. HIGHS 55 NW TO UPPER 60S SE. PARTLY CLOUDY TO CLOUDY FRIDAY NIGHT. WARMER. LOWS 45-55. AREAS OF FOG/LOW CLOUDS AGAIN LIKELY NW. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 300 TUESDAY... THE LATEST MODELS SUPPORT THE SLOWER TIMING OF THE COLD FRONT BY EARLY NEXT WEEK. THIS WILL ENSURE A WEEKEND OF WARM DRY WEATHER WITH TEMPS 20 TO 30 DEGREES ABOVE NORMAL. WE WILL HOLD OFF MENTION OF ANY SHOWERS UNTIL SUNDAY NIGHT OR MONDAY. BECOMING PARTLY CLOUDY SATURDAY. BREEZY AND WARMER. HIGHS IN THE UPPER 60S TO MID 70S. LOWS SAT NIGHT IN THE 50S (AVERAGE HIGHS ARE 48-53). SUNDAY... PARTLY SUNNY. HIGHS LOWER TO MID 70S. MONDAY... MOSTLY CLOUDY WITH A CHANCE OF SHOWERS. HIGHS IN THE 60S TO LOWER 70S SE. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 645 AM TUESDAY... WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE CAROLINAS. STRATOCU HAS SPREAD FROM SC NORTH ACROSS ALMOST ALL OF CENTRAL NC. CEILINGS GENERALLY VARY FROM 5000FT NORTH TO 3000FT SOUTH. BASED ON SATELLITE TRENDS AND HRRR MODEL MOISTURE FIELDS...MVFR CEILINGS ARE MOSTLY LIKELY IN THE NEXT 3-6 HOURS AT KFAY/KGSO/KINT. MVFR CEILINGS CANNOT BE RULED OUT AT KRDU AND/OR KRWI..BUT CONFIDENCE IS MUCH LOWER AT THESE SITES. WHILE SOME IMPROVEMENT IS FORECAST THIS AFTERNOON...THIS MOISTURE IS TRAPPED BENEATH A STRONG SUBSIDENCE INVERSION LOCATED NEAR 5000FT...SO CEILINGS ARE LIKELY TO REMAIN NEAR MVFR LEVELS THROUGHOUT THE DAY. TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT). OUTLOOK... AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT APPROACHES FROM THE SOUTH-SOUTHWEST. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...SMITH SHORT TERM...BADGETT LONG TERM...BADGETT AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1006 AM MST TUE JAN 8 2013 .UPDATE... && .SHORT TERM...MID LEVEL SHORT WAVE MOVING ACROSS EASTERN COLORADO AT THIS TIME. WEAK SUBSIDENCE BEHIND WAVE ALONG WITH CROSS MOUNTAIN FLOW OF 35 KTS COMBINED TO PRODUCE GUSTS AROUND 50 MPH ALONG THE FOOTHILLS OF BOULDER AND JEFFERSON COUNTIES WITH THE GJT-DEN 1500M PRESSURE GRADIENT AROUND 10.21 MB. WINDS STILL EXPECTED TO DECREASE BY THE AFTERNOON AS NORTHWEST FLOW ALOFT WEAKENS AND CROSS MOUNTAIN FLOW DECREASES TO AROUND 20 KTS. CURRENT FORECAST TRENDS OF DECREASING WINDS STILL LOOKING REASONABLE. A FEW LIGHT SNOW SHOWERS STILL POSSIBLE ALONG WEST FACING SLOPES OF THE GORE AND PARK RANGES AS RAP CROSS SECTIONS KEEP SOME MOISTURE TRAPPED IN THAT AREA. OTHERWISE...CLOUDS TO BE ON THE DECREASE AS SUBSIDENCE AND DRIER AIR DOMINATES. TEMPERATURES SLIGHTLY COOLER TODAY AS COLD AIR ADVECTION SPREADS OVER AREA. CURRENT TEMPERATURE GRIDS STILL SEEM REASONABLE. PERSISTANT SURFACE BASED INVERSIONS TO KEEP MOUNTAIN VALLEYS QUITE COLD...ESPECIALLY OVERNIGHT. .AVIATION...SOUTHWEST TO WEST WINDS ACROSS AREA AIRPORTS AT THIS TIME. LATEST RAP AND HRRR INDICATING WINDS TO WEAKEN AND GO CLOCKWISE DURING THE AFTERNOON...WITH NORTHEAST TO EAST WINDS AT DEN AND APA. WINDS SHOULD REMAIN MORE NORTHWEST AT BJC. SPEEDS SHOULD REMAIN BELOW 10 KTS...THOUGH SOME GUSTS TO 20 KTS WILL BE POSSIBLE AT BJC. WILL BE MAKING ADJUSTMENTS TO THE DIRECTION TO FOLLOW THE RAP/HRRR SOLUTIONS. VFR TO PREVAIL WITH CEILINGS ABOVE 10000 FEET. && .PREV DISCUSSION... /ISSUED 355 AM MST TUE JAN 8 2013/ SHORT TERM...A COUPLE MID/HIGH LEVEL CLOUD BANDS PASSING OVER THE FORECAST AREA AT THIS HOUR ASSOCIATED WITH A PASSING SHORTWAVE TROUGH. NEXT FEW HOURS SHOULD SEE NORTHWESTERLY WINDS ALOFT INCREASING WITH COLD ADVECTION. MODEL CROSS SECTIONS INDICATE A 30-35 KT WEST-NORTHWEST MTN TOP WIND COMPONENT NOW THROUGH 15Z THIS MORNING. COULD SEE GUSTY WESTERLY SFC WINDS OF 25-35 KTS DEVELOPING IN THE NEXT HOUR OR SO ON THE RIDGETOPS AND EAST SLOPES OF THE FRONT RANGE. AREAS ALONG THE BASE OF THE FOOTHILLS IN NRN JEFFERSON...BOULDER AND LARIMER COUNTIES COULD ALSO SEE OCCASIONAL GUSTS OF 25-30 KTS THRU 15Z THIS MORNING. DO NOT SEE MUCH IF ANY PRECIPITATION WITH THIS PASSING DISTURBANCE AS THE SUB-CLOUD LAYER APPEARS QUITE DRY. LATER THIS MORNING WITH THE TROUGH EXITING THE AREA...SHOULD SEE CLEARING AS WELL AS A DECREASE IN WIND SPEEDS WITH THE FLOW ALOFT WEAKENING AND WITH THE CROSS STATE PRESSURE GRADIENT RELAXING. LOOKING FOR HIGH TEMPERATURES TODAY TO GENERALLY BE 2-3C ABOVE AVERAGE FOR THE DATE...WITH MID 40S-LOWER 50S ON THE PLAINS...AND 20S-30S IN THE HIGH COUNTRY. ALTHOUGH LOW LYING AREA IN THE HIGH MOUNTAIN VALLEYS SUCH AS ALONG THE COLORADO RIVER IN MIDDLE PARK AND AROUND ANTERO AND ELEVENMILE CANYON RESERVOIRS IN SOUTH PARK WILL ONCE AGAIN STRUGGLE TO CLIMB ABOVE THE SINGLE DIGITS DUE TO A STRONG AND PERSISTENT SFC BASED TEMPERATURE INVERSION. OVERNIGHT NORTHWEST FLOW ALOFT IN THE EVENING TURNS ZONAL/WESTERLY AFTER MIDNIGHT WITH HEIGHT RISES ACROSS UTAH AND WESTERN COLORADO. TEMPERATURES TONIGHT WILL BE SLIGHTLY WARMER ON THE PLAINS AND AT HIGHER ELEVATIONS. ALTHOUGH A STRONG NOCTURNAL INVERSION WILL ONCE AGAIN RESULT IN ANOTHER NIGHT OF BITTER COLD TEMPERATURES... AS MUCH AS 15 TO 20 F BELOW ZERO...FOR THOSE SAME MTN VALLEY LOCATIONS MENTIONED ABOVE. LONG TERM...WLY FLOW ALOFT WILL BE OVER THE AREA ON WED AND THEN BECOME MORE SWLY ON THU AS AN UPPER LEVEL TROUGH DEVELOPS OVER THE WRN US. OVERALL IT SHOULD BE DRY OVER THE RGN THRU THU WITH ABV NORMAL TEMPS ACROSS NERN CO. HIGHS BOTH DAYS SHOULD BE IN THE 50S ALONG THE FRONT RANGE WITH SLIGHTLY COOLER READINGS OVER THE FAR NERN PLAINS. FOR FRI INTO FRI NIGHT BOTH THE GFS AND ECMWF WANT TO MOVE THE UPPER LEVEL TROUGH OVER THE WRN US QUICKLY EASTWARD ACROSS THE AREA. SOME OF THE ENSEMBLE MEMBERS ARE SLOWER BUT FOR NOW WILL TREND FCST WITH FASTER SOLUTION. MEANWHILE THERE WILL BE A STG CDFNT MOVING INTO NERN CO DURING THE DAY ON FRI. BOTH THE GFS AND ECMWF HAVE THIS FNT ACROSS MOST OF THE PLAINS BY AFTN SO WILL HAVE HIGHS RANGING FM THE MID TO UPPER 20S NR THE CO-WY BORDER WITH LOWER TO MID 40S ACROSS SRN LINCOLN COUNTY. AS FAR AS SNOW RIGHT NOW IF THE CURRENT TIMING OF THE TROUGH IS CORRECT THERE WILL BE A PERIOD OF DECENT QG ASCENT FRI AFTN INTO FRI NIGHT WITH FAVORABLE LAPSE RATES. THUS SHOULD SEE SNOW IN THE MTNS THRU THE DAY ON FRI INTO FRI NIGHT. OVER NERN CO WITH UPSLOPE COMPONENT IN PLACE BEST CHC OF SNOW LOOKS TO BE FRI AFTN INTO FRI FRI EVENING WITH ACCUMULATIONS CERTAINLY POSSIBLE. BY SAT THE UPPER LEVEL TROUGH MOVES ENE OF THE AREA LEAVING NW FLOW ALOFT OVER THE AREA. ENOUGH MOISTURE WILL LINGER IN THE MTNS FOR A CHC OF LIGHT SNOW ALTHOUGH OROGRAPHIC COMPONENT IS VERY WEAK. OVER NERN CO WEAK UPSLOPE COMPONENT IS SHOWN ALONG THE FRONT RANGE THRU THE DAY WITH LINGERING LOW LEVEL MOISTURE AND DECENT LAPSE RATES. THUS COULD SEE A CHC OF LIGHT SNOW MAINLY IN AND NR THE FOOTHILLS THRU THE AFTN HOURS. TEMPS WILL BE MUCH COLDER ON SAT AND IT WOULD NOT SURPRISE ME IF HIGHS DID NOT GET OUT OF THE TEENS ACROSS NERN CO. FOR SUN NNW FLOW ALOFT WILL REMAIN OVER THE AREA WITH STILL A CHC OF LIGHT SNOW IN THE MTNS. OVER NERN CO IT SHOULD BE DRY WITH TEMPS REMAINING WELL BLO NORMAL AS READINGS MAY STILL HAVE A HARD TIME GETTING ABV 20 DEGREES ESPECIALLY IF THERE IS SNOW COVER. BY MON THE FLOW ALOFT WILL BECOME MORE NWLY. ENOUGH MOISTURE MAY STILL LINGER IN THE MTNS FOR A SLIGHT CHC OF LIGHT SNOW. OVER NERN CO IT WILL BE DRY WITH TEMPS REMAINING WELL BLO NORMAL AS 850-700 MB TEMPS CHANGE VERY LITTLE. AVIATION...MID AND UPPER LEVEL CLOUDS PASSING OVER THE DENVER METRO AREA AT THIS EARLY HOUR MARK THE PASSAGE OF A WEAK UPPER LEVEL LOW PRESSURE TROUGH. DO NOT EXPECT TO SEE CLOUD BASES LOWERING MUCH BELOW 10 THOUSAND FT AGL NOW THROUGH 16Z THIS MORNING. AFTER THAT...SHOULD SEE SKIES GRADUALLY CLEARING AS CLOUD BASES RISE WITH DRIER NORTHWESTERLY FLOW ALOFT SPREADING OVER THE AREA. WINDS NEAR THE FOOTHILLS SUCH AS AT BJC WILL BE WEST-SOUTHWEST AT 10-15KT FOR MUCH OF THE DAY...WITH POSSIBLE GUSTS TO AROUND 25 KTS NOW THROUGH 15Z. OTHERWISE SOUTH- SOUTHWEST WINDS OF 8-13KTS WILL PREVAIL AT DIA AND APA TODAY... ALTHOUGH MAY SEE A SHORT PERIOD OF WESTERLY WINDS OF 13-18 KTS EARLY THIS MORNING WITH PASSAGE OF THE UPPER LEVEL TROUGH AXIS. FOR TONIGHT UNDER CLEAR/MOSTLY CLEAR SKIES...DENVER AREA AIRPORTS SHOULD SEE THE TYPICAL DRAINAGE WIND PATTERN SET UP WITH SUNSET WITH SPEEDS GENERALLY UNDER 12KTS. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....RPK AVIATION...D-L
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
344 PM CST TUE JAN 8 2013 .SHORT TERM... ISSUED AT 335 PM CST TUE JAN 8 2013 (TONIGHT) A NRN STREAM SHORTWAVE WILL PASS NORTH OF THE AREA TONIGHT ALTHOUGH IT WILL DRAG A WEAK CDFNT THROUGH THE CWA. ATTM NO PCPN IS EXPECTED WITH THE CDFNT DUE TO THE INITIALLY DRY AIR MASS PER 12Z SGF SOUNDING...LIMITED MOISTURE ACCOMPANYING THE NRN STREAM SHORTWAVE...AND UNFAVORABLE DYNAMICS THIS FAR SOUTH OF THE VORT MAX. THE PRIMARY EFFECT OF THE CDFNT WILL BE TO CAUSE WINDS TO VEER FM SLY TO WLY OVERNIGHT. ALTHOUGH THE NAM/SREF SEEM TO BE OVERDOING THE LOW LEVEL MOISTURE BASED ON THE LATEST OBS...MID-LEVEL MOISTURE SHOULD BEGIN MOVING NWD TONIGHT IN RESPONSE TO A STRONG LOW PRESSURE SYSTEM IN NRN MEXICO/SRN TX. SOME PCPN HAS ALREADY DVLPD OVER AR AHEAD OF THE SRN SYSTEM AND IT IS POSSIBLE THAT THERE MAY BE ENOUGH LIFT TO SUPPORT A FEW SPRINKLES ACROSS THE SRN CWA. KANOFSKY && .LONG TERM... ISSUED AT 335 PM CST TUE JAN 8 2013 (WEDNESDAY THROUGH TUESDAY) A GOOD POTENTIAL FOR SIGNIFICANT QPF IS EXPECTED FOR WED NGT THROUGH THU NGT AS THE UPPER LEVEL LOW OVER OLD MEXICO MOVES SLOWLY NEWD THROUGH THE SRN PLAINS WED AND WED NGT...THEN EVENTUALLY MOVES NEWD THROUGH MO THU NGT. PREFER THE MORE NRN SOLUTION OF THE 500 MB LOW TRACK OF THE NAM AND ECMWF MODELS OVER THE GFS. MOST OF THE PRECIPITATION SHOULD REMAIN S OF OUR FORECAST AREA ON WED...BUT THEN SPREAD NEWD INTO MUCH OF THE REGION WED NGT AS A STRONG SLY LOW LEVEL JET BRINGS LOW LEVEL MOISTURE NWD INTO MUCH OF MO AND SRN IL. SHOWERS AND AT LEAST A FEW THUNDERSTORMS CAN BE EXPECTED ON THU AS A WEAK SFC LOW AND WARM FRONT LIFT NWD INTO SRN MO...WITH INCREASING UPPER LEVEL DIVERGENCE OVER OUR AREA AHEAD OF THE APPROACHING UPPER LEVEL TROUGH. MUCH OF THE PRECIPITATION SHOULD SHIFT E OF OUR AREA BY LATE THU NGT AS THE UPPER LEVEL LOW OPENS UP AND WEAKENS AS IT MOVES TOWARDS THE GREAT LAKES REGION. UNSEASONABLY WARM WEATHER WILL CONTINUE ON FRI WITH S-SWLY LOW LEVEL WINDS ALONG WITH A CLEARING SKY. BOTH THE NAM AND ECMWF MODELS FORECAST 850 MB TEMPERATURES OF AROUND 12 DEGREES C BY 00Z SAT ACROSS MUCH OF OUR AREA. WILL LIKELY HAVE HIGHS IN THE LOWER 60S ACROSS MOST OF THE AREA ON FRI. SAT WILL BE THE LAST DAY OF ABOVE NORMAL TEMPERATURES AS A COLD FRONT DROPS SOUTHEASTWARD THROUGH OUR FORECAST AREA LATE FRI NGT AND SAT. ALTHOUGH THE FRONT SHOULD MOVE THROUGH DRY THE MODELS DO GENERATE POST FRONTAL PRECIPITATION SAT NGT AS A WEAK SFC WAVE MOVES ALONG THE FRONT WITH AN APPROACHING POSITIVELY TILTED UPPER LEVEL TROUGH WELL WEST OF THE AREA. LOOKS LIKE MOST OF THE PRECIPITATION WILL BE ACROSS SERN MO AND SWRN IL IN THE WARMER AIR...BUT COULD NOT RULE OUT A LITTLE LIGHT SNOW N AND W OF STL IN THE COLDER AIR. THE POTENTIAL FOR AT LEAST LIGHT PRECIPITATION MAY CONTINUE ACROSS SERN MO AND SWRN IL UNTIL MON WHEN A STRONG SFC RIDGE OVER THE NRN PLAINS FINALLY BUILDS SEWD INTO MO WITH THE COLD FRONT SHIFTING WELL SE OF OUR AREA. MUCH COLDER...MORE SEASONAL TEMPERATURES CAN BE EXPECTED SUN THROUGH TUE. GKS && .AVIATION... ISSUED AT 1124 AM CST TUE JAN 8 2013 VFR THROUGH THE PD WITH MID AND HIGH LEVEL CLOUDS. INITIALLY SLY WINDS WILL VEER SWLY AHEAD OF A WEAK COLD FRONT THEN BECOME WLY AFTER FROPA. GENERALLY FOLLOWED THE RAP/ECMWF FOR CIG TRENDS SINCE NAM/SREF APPEAR TO BE TOO MOIST AT LOW LEVELS. IF SFC WINDS DECOUPLE TONIGHT THEN LLWS MAY BECOME A CONCERN BETWEEN 03-09Z BASED ON RAP FCSTS OF WINDS ALOFT. SPECIFICS FOR KSTL...VFR THROUGH THE PD WITH MID AND HIGH LEVEL CLOUDS. INITIALLY SLY WINDS WILL VEER SWLY AHEAD OF A WEAK COLD FRONT THEN BECOME WLY AFTER FROPA. KANOFSKY && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1138 AM CST TUE JAN 8 2013 .SHORT TERM... ISSUED AT 356 AM CST TUE JAN 8 2013 (TODAY) SOUTHERLY FLOW TO PERSIST ACROSS THE REGION TODAY AHEAD OF A WEAK COLD FRONT. IN THE MEANTIME...HIGH THIN CLOUDS TO SLIDE NORTHEAST ACROSS AREA...BUT DESPITE THE CLOUDS...WILL SEE TEMPS WARM UP INTO THE UPPER 40S TO MID 50S WITH THE WARMEST TEMPERATURES OVER CENTRAL MO. BYRD && .LONG TERM... ISSUED AT 356 AM CST TUE JAN 8 2013 (TUESDAY NIGHT - WEDNESDAY) THE WARMTH WILL PERSIST THRU THE PERIOD AS COLD AIR REMAINS LOCKED NORTH OF THE POLAR JET STREAM ALONG THE CANADIAN BORDER. SPLIT FLOW STHRN STREAM CUT OFF LOW CONTINUES E ACROSS NTHRN MEXICO. DECENT SHORT WAVE WILL PASS NORTH OF THE AREA TUESDAY NIGHT. THIS WILL ALLOW A WEAK COLD FRONT TO DROP INTO THE CWA OVERNIGHT. THE BNDRY DOESN`T HAVE MUCH PUSH TO IT SO IT STALLS AND WASHES OUT WEDNESDAY MORNING. THE ATMOSPHERE IS FAIRLY DRY SO THE SHORT WAVE AND ASSOC FRONT SHOULDN/T PRODUCE MUCH MORE THAN ENHANCED MID/HIGH LEVEL CLOUDINESS. HIGH PRESSURE QUICKLY MOVES EAST ON WEDNESDAY. WINDS BECOME EASTERLY IN THE WAKE OF THE HIGH AND IN ADVANCE OF THE STORM SYSTEM DUE IN FOR WEDNESDAY NIGHT. THE CUT-OFF LOW MAKES A NE TURN AND CROSSES THE RIO GRNADE INTO TX LATE IN THE PERIOD. MOS WAS IN DECENT AGREEMENT FOR TUESDAY NIGHT SO WENT WITH A BLEND. WENT ABOVE THE WARMER MAV ACROSS THE NTRHN CWA WEDNESDAY. FOR THE SOUTH...USED A BLEND AS THE GUIDANCE WAS NOT IN VERY GOOD AGREEMENT. SOME PLACES THE MAV WAS WARMER...LIKE KFAM...WHILE OTHERS IT WAS THE MET...KSAR AND KSLO. THIS IS DUE TO THE NAMS FASTER SOLUTION AND QUICKER ONSET OF PRECIP ACROSS THE SOUTH. (WEDNESDAY NIGHT - THURSDAY NIGHT) UPPER LOW MOVES FROM TX WEDNESDAY NIGHT AND TRANSITIONS TO AN OPEN WAVE ACROSS THE GRT LKS BY FRIDAY MORNING. THE MODELS HAVE COME INTO BETTER AGREEMENT IN THE PAST 24 HRS AS TO LOCATION. THE NAM SOLUTION WRT THE 500MB LOW MOVING FURTHER EAST. THIS GROUP OF SOLUTIONS...NAM/SREF/LOCAL WRF...ARE CONSIDERABLY FASTER THAN THE ECMWF/GEM WHILE GFS BASICALLY SPLITS THE DIFFERENCE. THIS FEATURE IS AGAIN LIKELY NOT BEING SAMPLED WELL DUE TO HOW FAR INTO MEXICO IT HAS PROGRESSED. THE ENERGY COMING INTO THE NW COAST OBVIOUSLY ISN/T BEING SAMPLED WELL EITHER. UNTIL THEY ARE...THESE DIFFERENCES ARE LIKELY NOT TO BE RESOLVED. DO NOT HAVE A STRONG OPINION ON EITHER SCENARIO...BUT IF HAD TO MAKE A CHOICE...WOULD GO WITH THE GFS AS A GOOD COMPROMISE. THE ECMWF SEEMS TOO SLOW OF AN OUTLIER ATM. THAT BEING SAID...I INHERITED A FASTER ONSET TO PRECIP THAN LAST NIGHT. CERTAINLY CAN/T RULE OUT THAT SCENARIO...SO DIDN/T CHANGE MUCH WITH REGARDS TO TIMING. I DID BUMP POPS UP FOR THE MIDNIGHT TO NOON THURSDAY TIME FRAME. DUE TO HOW FAR SOUTH THIS SYSTEM IS FCST TO DIG...IT IS EXPECTED TO PULL A REMARKABLE AMOUNT OF MOISTURE NORTH WITH IT. 850 MB DPS OF NEAR 10C AS FAR NORTH AS KSTL. THIS EQUATES TO PWATS OF 1-1.5 INCHES...WHICH IS 2+ SD ABOVE CLIMO. THUNDER STILL LOOKS POSSIBLE WITH THE AREAS ALONG AND S OF I44 IN MO AND I70 IN IL WITH THE BEST CHANCES. THESE SAME AREAS MAY SEE 1-2 INCHES OF PRECIP. DEPENDING ON THE EXACT TRACK OF THE LOW AND THE EVOLUTION OF THE DRY SLOT...A PORTION OF THE CNTRL CWA MAY SEE SOME SUN...MIX AND REALLY WARM UP. TRIED TO CONVEY THIS WITH LOWER 60S SOUTH OF I70. PRECIP SHOULD COME TO AN END THURSDAY EVENING. THE WARM CONVEYOR AHEAD OF THE FRONT SHOULD PUSH EAST WHILE PRECIP TIED TO THE UPPER LOW LIFTS NE. (FRIDAY - MONDAY) THE REGION REMAINS IN SPLIT FOR FOR ONE MORE DAY. AS THE LOW PULLS AWAY...THE CWA IS LEFT IN SW FLOW AT THE SFC AND ALOFT. FCST 850 TEMPS ARE FAIRLY REMARKABLE AT +10 TO +14 FRIDAY AFTN. IF WE ONLY MIX TO 925MB...CLIMO INDICATES HIGH OF AT LEAST 60-65. THE GFS HINTS THAT NW PORTIONS OF THE CWA MAY MIX TO GREATER THAN 900 MB. IF THIS OCCURS...THEN MAX TEMPS MAY REACH 65-70. NOT READY TO JUMP ON THAT YET...BUT IS CERTAINLY SOMETHING TO WATCH IN THE COMING DAYS AS THOSE TEMPS COME CLOSE IF NOT EXCEED EXISTING RECORDS FOR THE DATE. THE ENERGY THAT PUSHED THE CLOSED LOW INTO OUR AREA IS FCST TO EFFECTIVELY PHASE THE JET STREAMS. THIS WILL ALLOW A STRONG COLD FRONT INTO THE REGION OVER THE WKND. THE ARCTIC FRONT IS STILL ON TRACK TO PLOW THRU THE AREA SATURDAY. THE FRONT STALLS JUST TO OUR SE AS A WAVE OF LOW PRESSURE SLIDES NE ALONG THE FRONT SATURDAY AFTN AND SATURDAY NIGHT. PRECIP SHOULD OVERSPREAD THE SERN HALF OF THE CWA SATURDAY AFTN...CONTINUE SATURDAY NIGHT AND THEN END BY SUNDAY MORNING. ATTM IT APPEARS THAT THE MAJORITY OF THE PRECIP WILL BE LIQUID...BUT CAN/T RULE OUT WNTRY PRECIP ON THE WRN FRINGE OF THE PRECIP SHIELD. THE BNDRY DOESN/T SEEM TO MOVE MUCH THRU THE BEGINNING OF THE WEEK. THE GFS AND ECMWF HAVE RIPPLES OF LOW PRESSURE THAT CONTINUE TO MOVE ALONG THE FRONT PRODUCING WAVES OF PRECIP. TIMING AND PLACEMENT OF THESE PRECIP EVENTS VARY...BUT THE PATTERN BEARS WATCHING. THE ARCTIC FRONT CERTAINLY APPEARS TO HAVE INITIATED A PATTERN SHIFT AS THE MEAN LONG WAVE TROUGH SLOWLY WORKS ACROSS THE CONUS THRU THE WEEK KEEPING THINGS SEASONABLY COOL. THE ECMWF HINTS AT SPLIT FLOW AGAIN FOR NEXT WEEK WITH A CUT OFF LOW OFF THE CA COAST BY MONDAY. THANKFULLY THERE ARE SEVERAL DAYS TO WATCH THE WKND WX AND BEYOND. MILLER && .AVIATION... ISSUED AT 1124 AM CST TUE JAN 8 2013 VFR THROUGH THE PD WITH MID AND HIGH LEVEL CLOUDS. INITIALLY SLY WINDS WILL VEER SWLY AHEAD OF A WEAK COLD FRONT THEN BECOME WLY AFTER FROPA. GENERALLY FOLLOWED THE RAP/ECMWF FOR CIG TRENDS SINCE NAM/SREF APPEAR TO BE TOO MOIST AT LOW LEVELS. IF SFC WINDS DECOUPLE TONIGHT THEN LLWS MAY BECOME A CONCERN BETWEEN 03-09Z BASED ON RAP FCSTS OF WINDS ALOFT. SPECIFICS FOR KSTL...VFR THROUGH THE PD WITH MID AND HIGH LEVEL CLOUDS. INITIALLY SLY WINDS WILL VEER SWLY AHEAD OF A WEAK COLD FRONT THEN BECOME WLY AFTER FROPA. KANOFSKY && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1129 AM CST TUE JAN 8 2013 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... In the short term, concerns are focused on temperatures along with rainfall potential Wednesday night into Thursday. Early this morning, a large upper level low continued to spin over northern Mexico as a progressive upper trough crosses the Northern Plains. Due to an enhanced area of cirrus moving across the region, temperatures have remained in the 30s in most locations. Today: Upper troughing in the Northern Plains will establish weak surface troughing across portions of east central Kansas through northwestern Missouri. Winds ahead of this surface trough will again become breezy by afternoon, with abnormally warm 950:850 temperatures supporting temperatures into the 50s in many areas. Again, have followed short term RAP guidance for temperatures this afternoon which did an excellent job on Monday. The warmest temperatures may pool just ahead of this surface trough where readings could spike into the middle 50s. Tonight: The weak surface trough will move into the region washing out as it does so. A bit less cirrus may be possible given the northwesterly upper level flow. The resultant temperatures will fall into the upper 20s in most locations. Wednesday: The upper level low over northern Mexico will finally become dislodged as troughing enters the Pacific Northwest. Locally, an elongated west to east ridge of high pressure will remain over the area throughout the daytime hours, keeping winds light and variable. Temperatures, given the weak boundary and low level flow, will not be quite as warm as on Tuesday but should still climb near 50. Wednesday night: The upper level low will quickly begin to surge north by Wednesday evening with strong low-level moisture advection headed into the area. Showers and even embedded thunderstorms will overspread the area through the overnight hours. Models in reasonable agreement (less the NAM) that rain will reach the Interstate 70 corridor by midnight and northern Missouri by daybreak. Thursday: Tricky forecast as models indicate the deep upper low will lift across the CWA during the daytime hours. Rain should quickly lift northward in the morning, replaced with low cloud cover and periods of showers/drizzle. Temperatures will be rather difficult and highly dependent on the track of surface low pressure and surge of warm air ahead of the surface low. Model guidance suggests a weak surface low tracking north along with the upper low through eastern Kansas by Thursday afternoon. NAM is the most aggressive bringing near 60 degree readings into the CWA, but it is also the deepest and most progressive solution of all guidance. Prefer the weaker solutions of the GFS/SREF which still bring low 50s by the late afternoon hours. Dux Medium Range (Friday through Monday)... The medium range should start out very warm especially for the climatologically coldest week of the year for Kansas City (January 10-17). With 850mb temps between 12C-14C, if we can mix out enough, temperatures could easily range into the mid 50s to mid 60s. However, those warm temperatures will be short-lived as a cold front is forced into the forecast area Friday night in association with a broad and deep upper level trough that will be traversing the Rockies. This frontal passage looks to be dry as models are in good agreement that the best moisture transport is south and east of the forecast area. As such have lowered chance POPs inherited by the initialization to silent slight chance POPs for Saturday. The main effect of this cold front will be the marked change in temperatures. High temperatures across the CWA Saturday will experience a 20 degree range from near 30 across northern Missouri where cold air advection will be ongoing by day break...to near 50 across central Missouri where cold air doesn`t begin to advect in until later in the day. The upper level trough moves through the area on Sunday as high pressure builds in at the surface with highs in the mid 20s to lower 30s. Surface high pressure strengths over the area on Monday and with abundant sunshine highs will return to near normal for the coldest climatological week of the year with highs in the 30s. 73 && .AVIATION... For the 18Z TAFs...VFR conditions will persist. South-southwest winds will veer to the west this evening with the passage of a weak surface trough. Winds will continue to veer to the north Wednesday morning in response to the cut-off low approaching from the south. MJ && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1231 PM EST TUE JAN 8 2013 .SYNOPSIS... A COASTAL TROUGH JUST OFFSHORE WILL WEAKEN TONIGHT AS A RIDGE OF HIGH PRESSURE TO OUR NORTH EXPANDS. LOW PRESSURE MOVING NORTHEAST OUT OF THE PLAIN STATES WILL BRING A WARM FRONT ACROSS THE EASTERN CAROLINAS ON FRIDAY. HIGH PRESSURE WILL BRING AN END TO THE UNSETTLED WEATHER WITH WARM AND DRY CONDITIONS FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM TUESDAY...WELL WELL...THE COMBO OF THE HRRR/RUC MENTIONED EARLIER AS UNLIKELY APPEARS TO HAVE BEEN THE WAY TO GO. DESPITE THE SYNOPTIC PATTERN AND LOW LEVEL WINDS FAVORING A CONTINUATION OF THE WEDGE-LIKE CONDITIONS SKIES HAVE AT LEAST TEMPORARILY BECOME MOSTLY SUNNY ACROSS MOST OF OUR FORECAST AREA WEST OF THE IMMEDIATE NORTH CAROLINA COAST AND TEMPERATURES ARE ROCKETING THROUGH THE 50S. DENSER MID-LEVEL CLOUDS ACROSS SOUTHERN AND CENTRAL SOUTH CAROLINA WILL MOVE INTO THE REGION IN THE NEXT COUPLE OF HOURS WHICH SHOULD STOP THE TEMPERATURES FROM RISING...BUT UNTIL THEN BASED ON CURRENT DATA I AM EXPANDING THE AREA EXPECTED TO REACH 60-62 DEGREES TO COVER MOST OF OUR SOUTH CAROLINA FORECAST AREA EAST OF I-95 AND AWAY FROM THE BEACHES. ACROSS SE NORTH CAROLINA MOST PLACES SHOULD REACH THE UPPER 50S...EXCEPT WITHIN 5-10 MILES OF THE NEW HANOVER AND PENDER COUNTY COAST WHERE STUBBORN CLOUDS AND THE REMNANT OF THIS MORNING`S CHILLY LOW-LEVEL AIRMASS WILL HOLD TEMPERATURES SEVERAL DEGREES COOLER. PREVIOUS DISCUSSION FROM 930 AM FOLLOWS... HIGH PRESSURE ALONG THE MID-ATLANTIC COAST AND A WEAK COASTAL TROUGH ROUGHLY 30-40 MILES OFFSHORE ARE PRODUCING A COOL NORTHEAST WIND ACROSS THE EASTERN CAROLINAS. SATELLITE SHOWS LOW AND MID-LEVEL CLOUD COVER ASSOCIATED WITH MOIST ATLANTIC AIR OVERRIDING THE SHALLOW COLD AIRMASS INLAND. THERE ARE SOME SIZABLE HOLES IN THESE CLOUD DECKS MAINLY ACROSS EASTERN SOUTH CAROLINA...AND THIS IS COMPLICATING OUR FORECAST FOR TODAY. CONFIDENCE WITH RESPECT TO OUR HIGH TEMPERATURE FORECAST REMAINS RATHER LOW. THE BULK OF MODEL GUIDANCE INCLUDING THE LATEST RUC AND HRRR MODELS ARE SIGNIFICANTLY WARMER THAN OUR FORECAST TODAY. IN FACT...BLENDING THE RUC AND HRRR GIVES LOW TO MID 60S ACROSS MOST OF OUR AREA WITH 50S ONLY HANGING AROUND NEAR THE BEACHES AND AROUND LUMBERTON. THIS MAY BE UNREASONABLY WARM GIVEN THE WEDGE-LIKE CONFIGURATION TO LOW-LEVEL WINDS...MOSTLY CLOUDY SKIES...AND THE COASTAL TROUGH REMAINING OFFSHORE. THE ONLY AREA WHERE LOW 60S ARE CURRENTLY FORECAST IS IN THE NARROW ZONE OF EASTERN SOUTH CAROLINA EAST OF I-95 BUT AWAY FROM THE BEACHES INCLUDING CONWAY...SOUTHERN MARION COUNTY...INLAND GEORGETOWN COUNTY AND WILLIAMSBURG COUNTY. ELSEWHERE...MID 50S SHOULD PREDOMINATE. RADAR IMAGERY SHOWS A PATCH OF LIGHT RAIN SITUATED IN THE ZONE OF STRONGEST ISENTROPIC LIFT NEAR AND JUST EAST OF BALD HEAD ISLAND. THIS SHOULD SHIFT NORTH OVER THE NEXT FEW HOURS BUT WILL LARGELY DISSIPATE THIS AFTERNOON. OTHERWISE DRY CONDITIONS SHOULD CONTINUE. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 330 AM TUESDAY...DEVELOPING LOW PRESSURE SYSTEM OVER THE TEXAS GULF COAST WILL TRACK NORTH TOWARD THE GREAT LAKES THROUGH THE PERIOD. AS THE MID TO UPPER LOW DEEPENS OVER THE MID WEST...THE RIDGE BECOMES MORE AMPLIFIED UP THROUGH THE SOUTHEAST COAST. MODELS STILL SHOWING H5 HEIGHTS REACHING UP NEAR 588 DEM BY THURS MORNING. WAA WILL BRING 850 TEMPS UP CLOSE TO 12C BY THURS BUT A SHALLOW COOLER ON SHORE FLOW WILL EXIST AT THE SURFACE THROUGH MID WEEK. INTERESTING SCENARIO AS COASTAL TROUGH WILL EXIST UP THROUGH THE COASTAL CAROLINAS WITH COOLER NE FLOW INLAND AND SOUTHEAST FLOW OFF SHORE REACHING THE COAST. THIS COASTAL TROUGH WILL PROVIDE FOCUS FOR CLOUDS AND SOME PCP MAINLY TO THE SOUTH THROUGH WEDNESDAY WHILE HIGH PRESSURE TO THE NORTH WILL PUSH A BACKDOOR COLD FRONT INTO NORTH CAROLINA OVERNIGHT WED. THE GFS SHOWS THIS BOUNDARY MAKING IT INTO LOCAL CWA BY THURS MORNING BUT THEN RETURNING NORTH AS WARM FRONT. THIS MAY REINFORCE SHALLOW COOLER AIR BRIEFLY AT THE SURFACE WHILE WINDS ALOFT INCREASE OUT OF THE SOUTH AS STORM SYSTEM OVER THE MID WEST STRENGTHENS. EXPECT DECENT AMOUNT OF LOW LEVEL CLOUDS THROUGH WED BUT SUBSIDENCE AND DRY AIR THROUGH THE MID LEVELS SHOULD PREVENT MUCH IN THE WAY OF PCP UNTIL LATE WED INTO THURS WHEN COASTAL TROUGH/WARM FRONT MAKES PROGRESS INLAND AND NORTH. WILL KEEP BEST CHC OF MEASURABLE PCP AND HIGHEST QPF DURING THURS. SHOULD SEE AN END TO MOST OF THE PCP HEADING INTO THURS EVENING AS BEST LIFT SHIFTS NORTH OF AREA AS WARM FRONT GETS PULLED NORTH AS STORM SYSTEM MOVES UP INTO THE GREAT LAKES. OVERALL WILL SEE CLOUDS THROUGH MOST OF THE PERIOD AND BEST CHC OF PCP OVERNIGHT WED INTO EARLY THURS. TEMPS MAY BE A BIT TRICKY WITH CLOUDS AND PCP BEING OFFSET BY WAA AND RIDGE BUILDING ALOFT WITH H5 HEIGHT INCREASES. THEN THE BACKDOOR COLD FRONT MAY PROVIDE ANOTHER BURST OF VERY SHALLOW COOL AIR FOR THURS MORNING BEFORE WARM FRONT MOVES NORTH OF AREA. EXPECT MAX TEMPS UP INTO THE 60S AND LOWS REMAINING CLOSE TO 50 OR ABOVE. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 3 AM TUESDAY...STRONG RIDGE BUILDING UP FROM THE BAHAMAS UP THROUGH THE SOUTHEAST WILL BECOME TEMPORARILY DISRUPTED EARLY FRIDAY AS IT TRACKS ACROSS THE CAROLINAS. ONCE THIS SHORTWAVE CLEARS THE COAST IT WILL PUSH A COLD FRONT FARTHER EAST AWAY FROM AREA ALLOWING HIGH PRESSURE TO DOMINATE THROUGH THE WEEKEND INTO EARLY NEXT WEEK. THE RIDGE AXIS WILL RIDE UP RIGHT ALONG THE SOUTHEAST COAST WITH CENTER OF THE SURFACE HIGH DISPLACED TO THE EAST. THIS WILL PRODUCE A DEEP W-SW RETURN FLOW THROUGH MOST OF THE PERIOD WITH PLENTY OF SUBSIDENCE AND DRY AIR THROUGH THE MID LEVELS OF THE ATMOSPHERE. SOME LOW LEVEL MOISTURE SHOULD PRODUCE SOME CLOUDS THROUGH THE PERIOD. H5 HEIGHTS REMAIN AROUND 585 DEM AS RIDGE HOLDS ON TIGHT THROUGH THE WEEKEND. 850 TEMPS HOLD UP TO 13 TO 14 C IN WAA INTO EARLY NEXT WEEK. OVERALL EXPECT TEMPS TO BE WELL ABOVE NORMAL WITH AFTERNOON HIGHS INTO THE 70S AND OVERNIGHT LOWS CLOSE TO NORMAL HIGHS FOR THIS TIME OF YEAR...IN THE MID 50S. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... AS OF 18Z...VISIBLE SATELLITE IMAGERY SHOWS SCT/BKN LOW TO MID LEVEL CLOUDS ACROSS THE CWA ASSOCIATED WITH A WEAK COASTAL TROUGH. THIS CLOUD COVER IS EXPECTED TO LINGER INTO THE OVERNIGHT HOURS. MOIST RETURN FLOW AROUND THE HIGH PRESSURE CENTERED OFFSHORE HAS INCREASED DEWPOINTS ACROSS THE AREA. FORECAST SOUNDINGS SHOW A PRONOUNCED LOW-LEVEL INVERSION DEVELOPING OVERNIGHT...WHICH SHOULD TRAP THIS MOISTURE NEAR THE SURFACE AND SUPPORT FOG/STRATUS DEVELOPMENT EARLY WEDNESDAY. BASED ON THE LATEST MODEL GUIDANCE...HAVE INCREASING CONFIDENCE FOR MVFR CIGS/VSBYS AT ALL TERMS AFTER 06Z...BECOMING IFR IN THE EARLY MORNING HOURS. CONDITIONS SHOULD IMPROVE TO MVFR BY LATE WEDNESDAY MORNING. EXPECT EAST WINDS AOB 8 KNOTS TODAY WITH LIGHT AND VARIABLE WINDS OVERNIGHT. EXTENDED OUTLOOK...SLIGHT CHANCE OF SHOWERS LATE WEDNESDAY INTO THURSDAY. POSSIBLE MVFR/IFR CIGS/VSBYS THURSDAY MORNING. VFR DEVELOPING FRIDAY AND PERSISTING THROUGH SUNDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM TUESDAY...COOL NORTHEAST WINDS CONTINUE ACROSS THE COASTAL WATERS...ALTHOUGH WITH WIND SPEEDS NOTABLY LESS THAN OBSERVED 3-6 HOURS AGO. THIS IS INLINE WITH OUR PREVIOUS FORECAST AND NO SIGNIFICANT CHANGES ARE NEEDED THROUGH THIS EVENING. PREVIOUS DISCUSSION FROM 930 AM FOLLOWS... BASED ON DATA FROM THE FRYING PAN SHOALS BUOY SHOWING A SOUTHEAST WIND AND 66 DEGREE AIR TEMPERATURES...THE COASTAL TROUGH LIES JUST TO THEIR WEST. ALL OTHER BUOY AND COASTAL LOCATIONS HAVE MUCH COLDER AIR TEMPERATURES WITH NORTH TO NORTHEAST WINDS. MODEL CONSENSUS IS THIS TROUGH SHOULD WEAKEN THIS AFTERNOON AND ESPECIALLY TONIGHT AS THE HIGH ALONG THE MID-ATLANTIC COAST NUDGES BACK TO THE SOUTH. RADAR SHOWS SOME PATCHY LIGHT RAIN JUST EAST OF CAPE FEAR CURRENTLY. THIS PRECIPITATION SHOULD MOVE SLOWLY NORTH THIS MORNING POTENTIALLY AFFECTING THE COASTAL WATERS NEAR CAROLINA BEACH BEFORE DISSIPATING THIS AFTERNOON. THE SURGE OF STRONG NORTH-NORTHEAST WINDS EARLIER THIS MORNING IS DIMINISHING AND BY THIS AFTERNOON WIND SPEEDS SHOULD REMAIN BELOW 15 KNOTS. SEAS HAVE ALSO STARTED DIMINISHING WITH 5 FT SEAS AT THE FRYING PAN SHOALS BUOY AND 4 FT AT THE NEARSHORE WRIGHTSVILLE BEACH BUOY. THE EXERCISE CAUTION HEADLINE WILL CONTINUE FOR THE NC WATERS THROUGH 11 AM. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...COASTAL TROUGH ON WED BECOMES DAMPENED AS HIGH PRESSURE PUSHES A BACK DOOR COLD FRONT SOUTH. SHOULD SEE LIGHT E-SE FLOW THROUGH WED 10 KTS OR LESS. FLOW MAY SHIFT AROUND TO THE NE BRIEFLY EARLY THURS AS WEAK BACKDOOR FRONT MOVES INTO AREA BUT THIS WILL MOVE BACK NORTH AS WARM FRONT ON THURSDAY WITH AN INCREASING SOUTHERLY FLOW DEVELOPING THURS NIGHT. SEAS WILL BASICALLY REMAIN 3 FT OR LESS THROUGH THURS MORNING AND THEN WILL RISE UP TO 3 TO 5 FT IN INCREASING SOUTHERLY PUSH LATE THURS INTO FRI. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3 AM TUESDAY...SOUTHERLY FLOW AROUND 15 KTS WILL VEER TO THE SOUTHWEST AND LIGHTEN THROUGH THE FIRST HALF OF THE WEEKEND AS HIGH PRESSURE OVER THE LOCAL WATERS SHIFTS SOUTH AND WEST. OVERALL GRADIENT WILL RELAX THROUGH SATURDAY. EXPECT WINDS TO LIGHTEN TO 10 KTS OR LESS BY LATE SAT WITH SEAS DIMINISHING FROM 3-5 FEET ON FRI DOWN TO 2 TO 3 FT BY SAT NIGHT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...RGZ AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1210 PM EST TUE JAN 8 2013 .SYNOPSIS... A COASTAL TROUGH JUST OFFSHORE WILL WEAKEN TONIGHT AS A RIDGE OF HIGH PRESSURE TO OUR NORTH EXPANDS. LOW PRESSURE MOVING NORTHEAST OUT OF THE PLAIN STATES WILL BRING A WARM FRONT ACROSS THE EASTERN CAROLINAS ON FRIDAY. HIGH PRESSURE WILL BRING AN END TO THE UNSETTLED WEATHER WITH WARM AND DRY CONDITIONS FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM TUESDAY...WELL WELL...THE COMBO OF THE HRRR/RUC MENTIONED EARLIER AS UNLIKELY APPEARS TO HAVE BEEN THE WAY TO GO. DESPITE THE SYNOPTIC PATTERN AND LOW LEVEL WINDS FAVORING A CONTINUATION OF THE WEDGE-LIKE CONDITIONS SKIES HAVE AT LEAST TEMPORARILY BECOME MOSTLY SUNNY ACROSS MOST OF OUR FORECAST AREA WEST OF THE IMMEDIATE NORTH CAROLINA COAST AND TEMPERATURES ARE ROCKETING THROUGH THE 50S. DENSER MID-LEVEL CLOUDS ACROSS SOUTHERN AND CENTRAL SOUTH CAROLINA WILL MOVE INTO THE REGION IN THE NEXT COUPLE OF HOURS WHICH SHOULD STOP THE TEMPERATURES FROM RISING...BUT UNTIL THEN BASED ON CURRENT DATA I AM EXPANDING THE AREA EXPECTED TO REACH 60-62 DEGREES TO COVER MOST OF OUR SOUTH CAROLINA FORECAST AREA EAST OF I-95 AND AWAY FROM THE BEACHES. ACROSS SE NORTH CAROLINA MOST PLACES SHOULD REACH THE UPPER 50S...EXCEPT WITHIN 5-10 MILES OF THE NEW HANOVER AND PENDER COUNTY COAST WHERE STUBBORN CLOUDS AND THE REMNANT OF THIS MORNING`S CHILLY LOW-LEVEL AIRMASS WILL HOLD TEMPERATURES SEVERAL DEGREES COOLER. PREVIOUS DISCUSSION FROM 930 AM FOLLOWS... HIGH PRESSURE ALONG THE MID-ATLANTIC COAST AND A WEAK COASTAL TROUGH ROUGHLY 30-40 MILES OFFSHORE ARE PRODUCING A COOL NORTHEAST WIND ACROSS THE EASTERN CAROLINAS. SATELLITE SHOWS LOW AND MID-LEVEL CLOUD COVER ASSOCIATED WITH MOIST ATLANTIC AIR OVERRIDING THE SHALLOW COLD AIRMASS INLAND. THERE ARE SOME SIZABLE HOLES IN THESE CLOUD DECKS MAINLY ACROSS EASTERN SOUTH CAROLINA...AND THIS IS COMPLICATING OUR FORECAST FOR TODAY. CONFIDENCE WITH RESPECT TO OUR HIGH TEMPERATURE FORECAST REMAINS RATHER LOW. THE BULK OF MODEL GUIDANCE INCLUDING THE LATEST RUC AND HRRR MODELS ARE SIGNIFICANTLY WARMER THAN OUR FORECAST TODAY. IN FACT...BLENDING THE RUC AND HRRR GIVES LOW TO MID 60S ACROSS MOST OF OUR AREA WITH 50S ONLY HANGING AROUND NEAR THE BEACHES AND AROUND LUMBERTON. THIS MAY BE UNREASONABLY WARM GIVEN THE WEDGE-LIKE CONFIGURATION TO LOW-LEVEL WINDS...MOSTLY CLOUDY SKIES...AND THE COASTAL TROUGH REMAINING OFFSHORE. THE ONLY AREA WHERE LOW 60S ARE CURRENTLY FORECAST IS IN THE NARROW ZONE OF EASTERN SOUTH CAROLINA EAST OF I-95 BUT AWAY FROM THE BEACHES INCLUDING CONWAY...SOUTHERN MARION COUNTY...INLAND GEORGETOWN COUNTY AND WILLIAMSBURG COUNTY. ELSEWHERE...MID 50S SHOULD PREDOMINATE. RADAR IMAGERY SHOWS A PATCH OF LIGHT RAIN SITUATED IN THE ZONE OF STRONGEST ISENTROPIC LIFT NEAR AND JUST EAST OF BALD HEAD ISLAND. THIS SHOULD SHIFT NORTH OVER THE NEXT FEW HOURS BUT WILL LARGELY DISSIPATE THIS AFTERNOON. OTHERWISE DRY CONDITIONS SHOULD CONTINUE. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 330 AM TUESDAY...DEVELOPING LOW PRESSURE SYSTEM OVER THE TEXAS GULF COAST WILL TRACK NORTH TOWARD THE GREAT LAKES THROUGH THE PERIOD. AS THE MID TO UPPER LOW DEEPENS OVER THE MID WEST...THE RIDGE BECOMES MORE AMPLIFIED UP THROUGH THE SOUTHEAST COAST. MODELS STILL SHOWING H5 HEIGHTS REACHING UP NEAR 588 DEM BY THURS MORNING. WAA WILL BRING 850 TEMPS UP CLOSE TO 12C BY THURS BUT A SHALLOW COOLER ON SHORE FLOW WILL EXIST AT THE SURFACE THROUGH MID WEEK. INTERESTING SCENARIO AS COASTAL TROUGH WILL EXIST UP THROUGH THE COASTAL CAROLINAS WITH COOLER NE FLOW INLAND AND SOUTHEAST FLOW OFF SHORE REACHING THE COAST. THIS COASTAL TROUGH WILL PROVIDE FOCUS FOR CLOUDS AND SOME PCP MAINLY TO THE SOUTH THROUGH WEDNESDAY WHILE HIGH PRESSURE TO THE NORTH WILL PUSH A BACKDOOR COLD FRONT INTO NORTH CAROLINA OVERNIGHT WED. THE GFS SHOWS THIS BOUNDARY MAKING IT INTO LOCAL CWA BY THURS MORNING BUT THEN RETURNING NORTH AS WARM FRONT. THIS MAY REINFORCE SHALLOW COOLER AIR BRIEFLY AT THE SURFACE WHILE WINDS ALOFT INCREASE OUT OF THE SOUTH AS STORM SYSTEM OVER THE MID WEST STRENGTHENS. EXPECT DECENT AMOUNT OF LOW LEVEL CLOUDS THROUGH WED BUT SUBSIDENCE AND DRY AIR THROUGH THE MID LEVELS SHOULD PREVENT MUCH IN THE WAY OF PCP UNTIL LATE WED INTO THURS WHEN COASTAL TROUGH/WARM FRONT MAKES PROGRESS INLAND AND NORTH. WILL KEEP BEST CHC OF MEASURABLE PCP AND HIGHEST QPF DURING THURS. SHOULD SEE AN END TO MOST OF THE PCP HEADING INTO THURS EVENING AS BEST LIFT SHIFTS NORTH OF AREA AS WARM FRONT GETS PULLED NORTH AS STORM SYSTEM MOVES UP INTO THE GREAT LAKES. OVERALL WILL SEE CLOUDS THROUGH MOST OF THE PERIOD AND BEST CHC OF PCP OVERNIGHT WED INTO EARLY THURS. TEMPS MAY BE A BIT TRICKY WITH CLOUDS AND PCP BEING OFFSET BY WAA AND RIDGE BUILDING ALOFT WITH H5 HEIGHT INCREASES. THEN THE BACKDOOR COLD FRONT MAY PROVIDE ANOTHER BURST OF VERY SHALLOW COOL AIR FOR THURS MORNING BEFORE WARM FRONT MOVES NORTH OF AREA. EXPECT MAX TEMPS UP INTO THE 60S AND LOWS REMAINING CLOSE TO 50 OR ABOVE. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 3 AM TUESDAY...STRONG RIDGE BUILDING UP FROM THE BAHAMAS UP THROUGH THE SOUTHEAST WILL BECOME TEMPORARILY DISRUPTED EARLY FRIDAY AS IT TRACKS ACROSS THE CAROLINAS. ONCE THIS SHORTWAVE CLEARS THE COAST IT WILL PUSH A COLD FRONT FARTHER EAST AWAY FROM AREA ALLOWING HIGH PRESSURE TO DOMINATE THROUGH THE WEEKEND INTO EARLY NEXT WEEK. THE RIDGE AXIS WILL RIDE UP RIGHT ALONG THE SOUTHEAST COAST WITH CENTER OF THE SURFACE HIGH DISPLACED TO THE EAST. THIS WILL PRODUCE A DEEP W-SW RETURN FLOW THROUGH MOST OF THE PERIOD WITH PLENTY OF SUBSIDENCE AND DRY AIR THROUGH THE MID LEVELS OF THE ATMOSPHERE. SOME LOW LEVEL MOISTURE SHOULD PRODUCE SOME CLOUDS THROUGH THE PERIOD. H5 HEIGHTS REMAIN AROUND 585 DEM AS RIDGE HOLDS ON TIGHT THROUGH THE WEEKEND. 850 TEMPS HOLD UP TO 13 TO 14 C IN WAA INTO EARLY NEXT WEEK. OVERALL EXPECT TEMPS TO BE WELL ABOVE NORMAL WITH AFTERNOON HIGHS INTO THE 70S AND OVERNIGHT LOWS CLOSE TO NORMAL HIGHS FOR THIS TIME OF YEAR...IN THE MID 50S. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 12Z...VFR/MVFR CIGS ACROSS THE AREA THIS MORNING AS SATELLITE IMAGERY DEPICTS PLENTY OF LOW-LEVEL CLOUD COVER ASSOCIATED WITH A COASTAL TROUGH. MOIST RETURN FLOW AROUND THE HIGH PRESSURE CENTERED OFFSHORE WILL KEEP THE LOW CLOUDS AROUND THROUGH THIS TAF PERIOD. IT APPEARS THAT LOW VFR CIGS WILL BE MOST PREVALENT ACROSS THE AREA TODAY...ALTHOUGH SOME MVFR CIGS ARE POSSIBLE AS WELL. COULD SEE SOME ISOLATED DRIZZLE ALONG THE COAST...BUT DECIDED IT WAS NOT WORTH MENTIONING IN TAFS. EXPECT EAST WINDS AOB 8 KNOTS TODAY...BECOMING LIGHT/CALM OVERNIGHT. MODEL SOUNDINGS AND GUIDANCE BOTH SUPPORT A FOG/STRATUS EVENT OVERNIGHT WITH ABUNDANT LOW-LEVEL MOISTURE IN PLACE ACROSS THE REGION. INCLUDED MVFR CIGS/VSBYS AFTER MIDNIGHT AT ALL TERMINALS...AND IFR CONDITIONS COULD DEVELOP TOWARDS THE END OF THE TAF PERIOD. EXTENDED OUTLOOK...POSSIBLE MVFR/IFR CIGS WEDNESDAY AND THURSDAY. SLIGHT CHANCE OF SHOWERS LATE WEDNESDAY INTO THURSDAY. VFR DEVELOPING FRIDAY AND PERSISTING THROUGH SATURDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM TUESDAY...COOL NORTHEAST WINDS CONTINUE ACROSS THE COASTAL WATERS...ALTHOUGH WITH WIND SPEEDS NOTABLY LESS THAN OBSERVED 3-6 HOURS AGO. THIS IS INLINE WITH OUR PREVIOUS FORECAST AND NO SIGNIFICANT CHANGES ARE NEEDED THROUGH THIS EVENING. PREVIOUS DISCUSSION FROM 930 AM FOLLOWS... BASED ON DATA FROM THE FRYING PAN SHOALS BUOY SHOWING A SOUTHEAST WIND AND 66 DEGREE AIR TEMPERATURES...THE COASTAL TROUGH LIES JUST TO THEIR WEST. ALL OTHER BUOY AND COASTAL LOCATIONS HAVE MUCH COLDER AIR TEMPERATURES WITH NORTH TO NORTHEAST WINDS. MODEL CONSENSUS IS THIS TROUGH SHOULD WEAKEN THIS AFTERNOON AND ESPECIALLY TONIGHT AS THE HIGH ALONG THE MID-ATLANTIC COAST NUDGES BACK TO THE SOUTH. RADAR SHOWS SOME PATCHY LIGHT RAIN JUST EAST OF CAPE FEAR CURRENTLY. THIS PRECIPITATION SHOULD MOVE SLOWLY NORTH THIS MORNING POTENTIALLY AFFECTING THE COASTAL WATERS NEAR CAROLINA BEACH BEFORE DISSIPATING THIS AFTERNOON. THE SURGE OF STRONG NORTH-NORTHEAST WINDS EARLIER THIS MORNING IS DIMINISHING AND BY THIS AFTERNOON WIND SPEEDS SHOULD REMAIN BELOW 15 KNOTS. SEAS HAVE ALSO STARTED DIMINISHING WITH 5 FT SEAS AT THE FRYING PAN SHOALS BUOY AND 4 FT AT THE NEARSHORE WRIGHTSVILLE BEACH BUOY. THE EXERCISE CAUTION HEADLINE WILL CONTINUE FOR THE NC WATERS THROUGH 11 AM. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...COASTAL TROUGH ON WED BECOMES DAMPENED AS HIGH PRESSURE PUSHES A BACK DOOR COLD FRONT SOUTH. SHOULD SEE LIGHT E-SE FLOW THROUGH WED 10 KTS OR LESS. FLOW MAY SHIFT AROUND TO THE NE BRIEFLY EARLY THURS AS WEAK BACKDOOR FRONT MOVES INTO AREA BUT THIS WILL MOVE BACK NORTH AS WARM FRONT ON THURSDAY WITH AN INCREASING SOUTHERLY FLOW DEVELOPING THURS NIGHT. SEAS WILL BASICALLY REMAIN 3 FT OR LESS THROUGH THURS MORNING AND THEN WILL RISE UP TO 3 TO 5 FT IN INCREASING SOUTHERLY PUSH LATE THURS INTO FRI. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3 AM TUESDAY...SOUTHERLY FLOW AROUND 15 KTS WILL VEER TO THE SOUTHWEST AND LIGHTEN THROUGH THE FIRST HALF OF THE WEEKEND AS HIGH PRESSURE OVER THE LOCAL WATERS SHIFTS SOUTH AND WEST. OVERALL GRADIENT WILL RELAX THROUGH SATURDAY. EXPECT WINDS TO LIGHTEN TO 10 KTS OR LESS BY LATE SAT WITH SEAS DIMINISHING FROM 3-5 FEET ON FRI DOWN TO 2 TO 3 FT BY SAT NIGHT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...RGZ AVIATION...BJR
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1036 AM CST TUE JAN 8 2013 .DISCUSSION... MAIN CHANGE FOR THIS MORNING WAS TO ADD SOME FZDL MENTION FOR THE REST OF THE MORNING INTO THE EARLY AFTERNOON. PRECIP HAS ENTERED THE CWA MAINLY FROM THE RED RIVER VALLEY WESTWARD. NOT MUCH SNOW ACCUMULATION SO FAR...BUT WE HAVE HAD A FEW REPORTS OF SLICK ROADS DUE TO FZDL AROUND FARGO TOWARDS CASSELTON. MODEL SOUNDINGS HAVE A SHALLOW MOIST LAYER WITH A DRY WARM LAYER ABOVE THROUGH MID AFTERNOON. TEMPS HAVE BEEN QUICK TO WARM UP THIS MORNING OVER THE WESTERN CWA EVEN WITH WINDS STILL FROM THE SOUTH. RAP SEEMS TO HAVE A GOOD HANDLE ON THE WARMING AND WENT CLOSE TO THAT MODEL SOLUTION FOR THE REST OF THE DAY. CONTINUE TO THINK THAT TEMPS WILL WARM TO CLOSE TO THE FREEZING MARK BY THIS AFTERNOON. MOST OF THE PRECIP SHOULD BE OVER THE NORTHEASTERN CWA BY LATE THIS POINT...AND THAT AREA SHOULD BE A BIT COLDER SO KEPT TYPE AS SNOW FOR NOW BUT WILL HAVE TO KEEP AN EYE ON IT. WINDS WILL ALSO BE AN ISSUE FROM LATE THIS AFTERNOON INTO THE EVENING. SOME OF THE MODEL GUIDANCE HAS THE NORTHWESTERN TO NORTH CENTRAL CWA FLIRTING WITH ADVISORY CRITERIA. ON THE OTHER HAND...MIXING WILL BE AT A MINIMUM AND THERE IS NO COLD AIR ADVECTION TO HELP BRING HIGHER LEVEL WINDS TO THE SFC. WILL HOLD OFF ON ANY HEADLINES FOR NOW AND REEVALUATE FOR THE AFTERNOON PACKAGE. && .AVIATION... WILL SEE INCREASING CLOUD COVER WITH PERIODS OF LIGHT SNOW FROM WEST TO EAST TODAY AS A LOW PRESSURE SYSTEM MOVES ACROSS THE REGION. VFR CEILINGS SHOULD DOMINATE...BUT MAY BRIEFLY DIP INTO THE MVFR RANGE WITH LIGHT SNOW AND REDUCTIONS IN VISIBILITY DOWN TO 1-5 SM. SOUTH-SOUTHWEST WIND WILL SHIFT TO THE WEST LATER THIS AFTERNOON AND EVENING BEHIND COLD FRONT WITH FREQUENT GUSTS AT OR ABOVE 30 KTS. && .PREV DISCUSSION... /ISSUED 353 AM CST TUE JAN 8 2013/ SHORT TERM...TODAY THROUGH THURSDAY NIGHT FORECAST CHALLENGES INCLUDE SNOW CHANCES/AMOUNTS AND WIND TODAY... FOLLOWED BY PRECIPITATION CHANCES AGAIN ON THURSDAY. GFS/NAM/ECMWF/ GEM ARE IN GOOD OVERALL AGREEMENT AND WILL USE A BLENDED SOLUTION. FOR TODAY...EASTERN PACIFIC SHORT-WAVE WILL MOVE ACROSS SOUTHERN CANADA AND THE NORTHERN PLAINS. SURFACE LOW WILL REMAIN NORTH OF THE BORDER...BUT THE COLD FRONT/TROUGH AXIS WILL MOVE ACROSS THE ND/MN BORDER AND INTO NORTHWEST MN BY 00 UTC TONIGHT. MID-LEVEL FRONTOGENESIS AND MOISTURE NOT ALL TOO IMPRESSIVE...BUT 300 HPA JET STREAK...COMBINED WITH MID-LEVEL CONVERGENCE WILL RESULT IN LIGHT SNOW MOVING ACROSS THE FORECAST AREA TODAY. WILL BE A HIGH POP/LOW QPF SCENARIO WITH THE BEST CHANCES FOR ACCUMULATING SNOWFALL ALONG AND NORTH OF THE HIGHWAY 2 CORRIDOR. MOST AREAS WILL SEE AN INCH OR LESS THROUGH WEDNESDAY MORNING...BUT UP TO 2 INCHES ARE POSSIBLE ACROSS THE LAKE OF THE WOODS AREA. WITH LESS FAVORABLE SOUTHERLY SURFACE WIND AHEAD OF THE FRONT AND MODEST COLD AIR ADVECTION IN ITS WAKE...EXPECT HIGH TEMPERATURES TODAY AT OR SLIGHTLY COOLER THAN YESTERDAY. MODELS STILL SHOW 40 TO 50 KTS AT 925 HPA ALONG AND WEST OF THE VALLEY BY 06 UTC TONIGHT. PREFER NAM/S DEPICTION OF MIXED BOUNDARY LAYER...WHICH DEEPENS IT TO AROUND 950 HPA OVERNIGHT. THIS PROVIDES AROUND 30 KTS TO MIX TO THE SURFACE IN AREA OF STRONGEST PRESSURE GRADIENT. AS A RESULT...LEANED TOWARDS HIGHEST LOCAL WRF GUIDANCE FOR WIND SPEED...BUT THIS STILL KEEPS IT JUST BELOW WIND ADVISORY CRITERIA (SUSTAINED 30 MPH). COULD SEE A FEW HOURS GREATER THAN 30 MPH WEST OF THE VALLEY...BUT CONFIDENCE NOT HIGH ENOUGH TO ISSUE ANY HEADLINES AT THIS TIME. WILL ALLOW DAY SHIFT TO RE-EVALUATE SINCE THE STRONGEST WIND WOULD BE DELAYED UNTIL AFTER 21 UTC THIS AFTERNOON. ALTHOUGH MAJORITY OF FALLING SNOW WILL END AFTER 00 UTC...DID INCLUDE AREAS OF BLOWING SNOW THIS EVENING INTO THE EARLY MORNING HOURS WEDNESDAY ALONG AND WEST OF THE VALLEY. REMAINING SNOW WILL MOVE OUT OF THE REGION BY WEDNESDAY MORNING WITH A SURFACE RIDGE MOVING ACROSS THE FORECAST AREA. EXPECT PLENTY OF SUNSHINE WEDNESDAY...BUT TEMPERATURES WILL BE A BIT COOLER WITH AFTERNOON HIGHS IN THE MID 20S ALONG THE CANADIAN BORDER TO NEAR 30 DEGREES ACROSS THE SOUTHERN VALLEY. WINDS WILL BE LIGHT FROM THE WEST-SOUTHWEST. MOST OF THURSDAY WILL BE DRY...BUT MODELS DO HINT THAT THE NORTHWEST FLANK OF A PRECIPITATION SHIELD ASSOCIATED WITH A GREAT LAKES LOW PRESSURE SYSTEM WILL CLIP PORTIONS OF THE SOUTHEAST FORECAST AREA THURSDAY EVENING. WILL KEEP 40 TO 60 POPS FOR THIS PERIOD ALONG AND EAST OF THE VALLEY. BIGGER STORY FOR THURSDAY WILL BE WARM TEMPERATURES WITH 850 HPA VALUES CLIMBING TO +6 C. THIS SHOULD TRANSLATE TO SURFACE TEMPERATURES IN THE MID 30S. IF PRECIPITATION DOES TRACK FARTHER NORTH...MAY NEED TO WATCH P-TYPE GIVEN WARM MID-LEVELS. LONG TERM...FRIDAY THROUGH MONDAY NIGHT MODELS ARE COMING INTO BETTER AGREEMENT WITH AN ACTIVE WEATHER PATTERN FOR FRI-SAT...WITH SW FLOW ALOFT. THERE ARE DIFFERENCES IN THE DETAILS AND EXACT TIMING...BUT ALL INDICATIONS POINTING TO ACCUMULATING SNOW POSSIBLE FRIDAY INTO SATURDAY...MUCH COLDER TEMPS AND NORTHERLY WINDS INCREASING. FOR NOW HAVE KEPT WITH CHANCE POPS FOR LIGHT SNOW FRI INTO SAT...BUT WE MAY NEED TO INCREASE THESE POPS WITH SEVERAL SHORTWAVES MOVING THROUGH. THE BEST CHANCE FOR ACCUMULATING SNOW AND POTENTIAL WINTER WEATHER HEADLINES WOULD BE FRI AFTERNOON INTO SATURDAY...ALTHOUGH TIMING OF THIS MAY CHANGE WITH PLENTY OF TIME TO RESOLVE MODEL DIFFERENCES. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ JR
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1158 AM CST TUE JAN 8 2013 .AVIATION... /18Z TAFS/ CONCERNS...ONGOING LOW CIGS/VSBY AND THUNDER POTENTIAL. INITIAL MASS OF LIGHT RAIN ASSOCIATED WITH LARGE UPPER LEVEL STORM SYSTEM OVER NORTHERN MEXICO HAS MOVED INTO N TEXAS THIS MORNING...BRINGING WIDESPREAD MVFR/AREAS OF IFR TO ALL SITES. AS MOISTURE INFLOW AND LIFT INCREASE AHEAD OF THIS SYSTEM LATER TODAY/TONIGHT...EXPECT WIDESPREAD RAIN AND IFR CONDITIONS TO DEVELOP AND PERSIST THROUGH AT LEAST MIDDAY WED. LIMITED INSTABILITY EXISTS ALOFT...INCREASING TO THE S AND E OF THE METROPLEX TAF SITES. GIVEN THIS...EXPECT OCCASIONAL THUNDER AT ALL TAF SITES THROUGH TONIGHT. SURFACE WINDS SHOULD CONTINUE TO BACK TO A NE-N DIRECTION TONIGHT AND INCREASE AS SURFACE LOW DEVELOPS OVER S TEXAS. 66 && .UPDATE... CURRENT FORECAST IS IN GOOD SHAPE AND ONLY MADE SOME MINOR CHANGES TO THE SKY/POP GRIDS TO ACCOUNT FOR CURRENT OBSERVATIONS. CURRENT ANALYSIS OF AVAILABLE 12Z GUIDANCE CONTINUES TO SHOW THAT WIDESPREAD HEAVY RAINFALL IS LIKELY THROUGH WEDNESDAY. INITIAL ACTIVITY HAS BEEN SOMEWHAT SCATTERED AS BROAD ISENTROPIC ASCENT OVERSPREADS THE AREA. LATEST RAP SOUNDINGS FROM ACROSS NORTH TEXAS INDICATE ABOUT 100-200J/KG OF ELEVATED INSTABILITY WHICH HAS BEEN SUFFICIENT FOR ISOLATED THUNDERSTORMS CAPABLE OF PRODUCING SMALL HAIL. AS DEEPER LARGE SCALE FORCING OVERSPREADS CENTRAL AND NORTH TEXAS TONIGHT...A WELL DEFINED WARM CONVEYOR BELT WILL BECOME ESTABLISHED AND AREAL COVERAGE OF PRECIPITATION IS EXPECTED TO INCREASE. HEAVIEST RAINS STILL EXPECTED OVERNIGHT TONIGHT INTO EARLY WEDNESDAY...SO NO CHANGES NEEDED ATTM TO THE FLASH FLOOD WATCH. THE THREAT FOR SEVERE WEATHER STILL APPEARS FAIRLY LOW AND SHOULD BE CONFINED TO THE SOUTHEAST COUNTIES LATE TONIGHT INTO WEDNESDAY. DUNN && .PREV DISCUSSION... /ISSUED 427 AM CST TUE JAN 8 2013/ MODEL GUIDANCE IS IN GOOD AGREEMENT AND NOW OFFERS A REASONABLE TRACK FEATURING MORE OF A SMOOTH PENDULUM SWING OF THE UPPER LOW THROUGH NORTHERN MEXICO TONIGHT BEFORE EJECTING NORTHEAST AND OVER NORTH CENTRAL TEXAS WEDNESDAY EVENING. THE MODELS HAVE BACKED OFF THE SLOWER/WOBBLY TRACK THAT TOOK THE LOW WELL WEST OF THE CWA. THIS MEANS THE SYSTEM WILL BE IN AND OUT MORE QUICKLY...AND TIMING FOR THE HEAVIEST RAINFALL AND MOST ROBUST CONVECTION NOW LOOKS LIKE TONIGHT AND WEDNESDAY MORNING. THIS ALSO MEANS THE WARM SECTOR WILL HAVE LESS TIME TO PENETRATE THE CWA WITH THE SEVERE THREAT RELEGATED TO THE FAR SE ZONES BETWEEN 3 AM AND 9 AM WED. ISENTROPIC LIFT HAS BEGUN ACROSS NORTH TEXAS AND CLOUDS WILL CONTINUE TO THICKEN AND LOWER THROUGH THE DAY. SHOWERS AND AREAS OF DRIZZLE HAVE ALREADY DEVELOPED ACROSS CENTRAL TEXAS. MODEL SOUNDINGS REVEAL MUCAPE VALUES OF 100 J/KG NORTH TO 500 J/KG SOUTH FOR PARCELS NEAR 800MB. THIS MEANS A FEW THUNDERSTORMS WILL DEVELOP ONCE THE ISENTROPIC LIFT BEGINS ON THE 325K SURFACE WHICH SHOULD OCCUR AFTER 9AM. SHOWERS/STORMS WILL BECOME NUMEROUS DURING THE DAY AND SPREAD N/NE. IN THE MEANTIME A DEVELOPING INVERTED SURFACE TROUGH AND LOW CENTER IN SOUTH TEXAS WILL CAUSE WINDS TO BACK TO THE NORTHEAST. COLD ADVECTION...CLOUDS AND RAIN WILL KEEP HIGHS IN THE UPPER 40S WEST TO LOW 50S EAST. ISENTROPIC LIFT INTENSIFIES SUBSTANTIALLY TONIGHT AS LOW LEVEL WIND FIELDS INCREASE AND BACK TO THE SOUTHEAST. MOISTURE FLUX AND THETA-E ADVECTION VALUES ARE VERY HIGH. CONSIDERING THE WARM CONVEYOR BELT WILL BE TAPPING INTO UNSEASONABLY HIGH PRECIPITABLE WATER VALUES OF ALMOST 2 INCHES IN THE GULF...THIS WILL ALLOW A WIDESPREAD AREA OF RAIN TO DEVELOP TONIGHT AND PERSIST INTO WEDNESDAY MORNING ACROSS NORTH TEXAS IN THE COLD SECTOR. WHILE RAINFALL RATES WILL LIKELY NOT EXCEED AN INCH PER HOUR...THE CONTINUOUS RAINS SHOULD HELP GENERATE EXCESSIVE RUNOFF. HEAVY RAIN EVENTS IN THE COLD SEASON TEND TO PRODUCE MORE RUNOFF THAN IN THE WARM SEASON. MOST VEGETATION IS DORMANT AND THEREFORE IT DOES NOT TAKE MUCH OF THE RAIN WATER OUT OF THE SOILS. WE ARE OUTLOOKED IN SLIGHT RISK FOR EXCESSIVE RAINFALL BY HPC AND HAVE ISSUED A FLASH FLOOD WATCH FOR AREAS WHERE WE EXPECT 2 TO 4 INCHES OF RAIN. THE METROPLEX IS ON THE EDGE OR JUST NORTHWEST OF THE HEAVY RAIN AXIS BUT WE BROUGHT THE WATCH INTO TARRANT/DALLAS/COLLIN COUNTIES BECAUSE THE URBANIZATION IS MORE SENSITIVE TO HEAVY RAINFALL. CONCERNING THE SEVERE WEATHER THREAT...A LINE OF STORMS SHOULD FORM IN SOUTH CENTRAL TEXAS THIS EVENING AND MOVE RATHER SLOWLY TO THE E/NE INTO OUR FAR SOUTH/SOUTHEAST ZONES AFTER 3 AM. ALTHOUGH THE WARM SECTOR DOES MAKE IT INTO THE SOUTHEAST ZONES AHEAD OF THE LINE...IT IS AT THE COOLEST TIME OF THE DAY. THIS WILL LIKELY LIMIT SURFACE BASED CAPE TO LESS THAN 100 J/KG IF ANYTHING AT ALL. BECAUSE SHEAR WILL BE HIGH...WE WILL HAVE TO MONITOR THIS CLOSELY...BUT AT THIS TIME THE SEVERE WEATHER THREAT LOOKS MORE CONDITIONAL THAN PREVIOUS FORECASTS WHICH HAD THE LINE MOVING IN DURING THE WARMER AFTERNOON HOURS. PASSAGE OF THE SURFACE TROUGH WILL BE SUCCEEDED BY DRY SLOT ALOFT WHICH SHOULD END MOST OF THE RAIN FROM WEST TO EAST DURING THE DAY WEDNESDAY. A FEW ELEVATED SHOWERS WILL REMAIN POSSIBLE WEDNESDAY EVENING BUT HAVE LOWERED POPS DUE TO THE FASTER TIMING. SOME WRAP AROUND CLOUDS WILL AFFECT THE NW ZONES THURSDAY...BUT OTHERWISE GENERALLY FAIR WEATHER WITH WARMER TEMPS DUE TO SW WINDS. FRIDAY WILL BE SUNNY AND WARMER WITH HIGHS NEAR 70. THE NEXT FRONT WILL ARRIVE SATURDAY AND BRING A SLIGHT CHANCE OF CONVECTION OVER THE EASTERN HALF OF THE AREA. TEMPS WILL COOL INTO THE 30S FOR LOWS SAT NIGHT...WITH THE UPPER LEVEL PATTERN FAVORABLE FOR SEVERAL DAYS OF COLD ADVECTION INTO NEXT WEEK. HIGH TEMPS WILL BE CHILLY SUNDAY INTO MID WEEK...GENERALLY IN THE LOW-MID 40S. GFS HAS BACKED OFF ON PRECIPITATION SUNDAY WHICH IS WHAT THE OTHER MODELS WERE FORECASTING...HOWEVER THERE IS A LITTLE MORE EVIDENCE THAT WE WILL CONTEND WITH POSSIBLE WINTRY PRECIPITATION FOR THE MIDDLE OF NEXT WEEK WHEN THE UPPER LEVEL PATTERN BECOMES MORE FAVORABLE. TR.92 && .CLIMATE... IN THE DALLAS/FORT WORTH METROPLEX...24-HOUR RAINFALL (MIDDAY TODAY TO MIDDAY WEDNESDAY) MAY REACH 3 INCHES. WHEN WAS THE LAST TIME DFW AIRPORT SAW THAT MUCH PRECIPITATION IN A 24 HOUR PERIOD? APRIL 8, 2012 (EASTER SUNDAY) - 2.23 MARCH 19-20, 2012 - 4.04 JANUARY 24-25, 2012 - 4.27 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 51 47 56 46 60 / 100 100 100 50 10 WACO, TX 52 49 57 45 64 / 100 100 100 30 10 PARIS, TX 52 47 57 51 60 / 90 100 100 80 10 DENTON, TX 50 45 54 45 59 / 100 100 90 60 10 MCKINNEY, TX 51 47 56 47 59 / 100 100 100 60 10 DALLAS, TX 51 47 56 46 60 / 100 100 100 50 10 TERRELL, TX 52 49 57 50 61 / 100 100 100 60 10 CORSICANA, TX 53 51 58 49 63 / 100 100 100 40 10 TEMPLE, TX 53 49 58 45 65 / 100 100 100 30 10 MINERAL WELLS, TX 48 44 54 42 60 / 90 100 80 50 10 && .FWD WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH FROM 6 PM CST THIS EVENING THROUGH WEDNESDAY AFTERNOON FOR TXZ094-095-104>107-118>123-133>135-145>148-158>162- 174-175. && $$ /
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1108 AM CST TUE JAN 8 2013 .UPDATE... CURRENT FORECAST IS IN GOOD SHAPE AND ONLY MADE SOME MINOR CHANGES TO THE SKY/POP GRIDS TO ACCOUNT FOR CURRENT OBSERVATIONS. CURRENT ANALYSIS OF AVAILABLE 12Z GUIDANCE CONTINUES TO SHOW THAT WIDESPREAD HEAVY RAINFALL IS LIKELY THROUGH WEDNESDAY. INITIAL ACTIVITY HAS BEEN SOMEWHAT SCATTERED AS BROAD ISENTROPIC ASCENT OVERSPREADS THE AREA. LATEST RAP SOUNDINGS FROM ACROSS NORTH TEXAS INDICATE ABOUT 100-200J/KG OF ELEVATED INSTABILITY WHICH HAS BEEN SUFFICIENT FOR ISOLATED THUNDERSTORMS CAPABLE OF PRODUCING SMALL HAIL. AS DEEPER LARGE SCALE FORCING OVERSPREADS CENTRAL AND NORTH TEXAS TONIGHT...A WELL DEFINED WARM CONVEYOR BELT WILL BECOME ESTABLISHED AND AREAL COVERAGE OF PRECIPITATION IS EXPECTED TO INCREASE. HEAVIEST RAINS STILL EXPECTED OVERNIGHT TONIGHT INTO EARLY WEDNESDAY...SO NO CHANGES NEEDED ATTM TO THE FLASH FLOOD WATCH. THE THREAT FOR SEVERE WEATHER STILL APPEARS FAIRLY LOW AND SHOULD BE CONFINED TO THE SOUTHEAST COUNTIES LATE TONIGHT INTO WEDNESDAY. DUNN && .AVIATION... /12Z TAFS/ CONCERNS...RAIN WITH DETERIORATING CIGS/VSBY...THUNDER POTENTIAL. CIGS/VSBY... AT 12Z TAF ISSUANCE TIME...SCATTERED SHOWERS HAVE ALREADY REACHED AREAS NORTH OF THE I-20 CORRIDOR. AS UPGLIDE INTENSIFIES FURTHER THIS MORNING...THE ACTIVITY WILL INCREASE IN INTENSITY AND AREAL COVERAGE. THE RESULTING TOP-DOWN SATURATION WILL RAPIDLY LOWER CEILINGS...WHICH SHOULD FALL INTO THE IFR CATEGORY BY EARLY AFTERNOON. VISIBILITY WILL DETERIORATE IN TANDEM BUT WILL REMAIN VARIABLE WITH INTERMITTENT PRECIPITATION. IFR CONDITIONS WILL PREVAIL THROUGHOUT THE REMAINDER OF THE EVENT...POTENTIALLY IMPROVING LATE WEDNESDAY. THUNDER... ALTHOUGH INITIAL CONVECTION HAS BEEN LOW-TOPPED SHOWERS... ENHANCEMENT ACROSS THE HILL COUNTRY IS INDICATIVE OF INCREASING INSTABILITY THAT WILL SPREAD NORTHWARD TODAY IN WARM ADVECTION REGIME. TIMING IN TAFS IS BASED ON EARLIER ARRIVAL/IMPACTS AT WACO THIS MORNING...THEN AFTERNOON THUNDER POTENTIAL AT METRO TERMINALS. 25 && .PREV DISCUSSION... /ISSUED 427 AM CST TUE JAN 8 2013/ MODEL GUIDANCE IS IN GOOD AGREEMENT AND NOW OFFERS A REASONABLE TRACK FEATURING MORE OF A SMOOTH PENDULUM SWING OF THE UPPER LOW THROUGH NORTHERN MEXICO TONIGHT BEFORE EJECTING NORTHEAST AND OVER NORTH CENTRAL TEXAS WEDNESDAY EVENING. THE MODELS HAVE BACKED OFF THE SLOWER/WOBBLY TRACK THAT TOOK THE LOW WELL WEST OF THE CWA. THIS MEANS THE SYSTEM WILL BE IN AND OUT MORE QUICKLY...AND TIMING FOR THE HEAVIEST RAINFALL AND MOST ROBUST CONVECTION NOW LOOKS LIKE TONIGHT AND WEDNESDAY MORNING. THIS ALSO MEANS THE WARM SECTOR WILL HAVE LESS TIME TO PENETRATE THE CWA WITH THE SEVERE THREAT RELEGATED TO THE FAR SE ZONES BETWEEN 3 AM AND 9 AM WED. ISENTROPIC LIFT HAS BEGUN ACROSS NORTH TEXAS AND CLOUDS WILL CONTINUE TO THICKEN AND LOWER THROUGH THE DAY. SHOWERS AND AREAS OF DRIZZLE HAVE ALREADY DEVELOPED ACROSS CENTRAL TEXAS. MODEL SOUNDINGS REVEAL MUCAPE VALUES OF 100 J/KG NORTH TO 500 J/KG SOUTH FOR PARCELS NEAR 800MB. THIS MEANS A FEW THUNDERSTORMS WILL DEVELOP ONCE THE ISENTROPIC LIFT BEGINS ON THE 325K SURFACE WHICH SHOULD OCCUR AFTER 9AM. SHOWERS/STORMS WILL BECOME NUMEROUS DURING THE DAY AND SPREAD N/NE. IN THE MEANTIME A DEVELOPING INVERTED SURFACE TROUGH AND LOW CENTER IN SOUTH TEXAS WILL CAUSE WINDS TO BACK TO THE NORTHEAST. COLD ADVECTION...CLOUDS AND RAIN WILL KEEP HIGHS IN THE UPPER 40S WEST TO LOW 50S EAST. ISENTROPIC LIFT INTENSIFIES SUBSTANTIALLY TONIGHT AS LOW LEVEL WIND FIELDS INCREASE AND BACK TO THE SOUTHEAST. MOISTURE FLUX AND THETA-E ADVECTION VALUES ARE VERY HIGH. CONSIDERING THE WARM CONVEYOR BELT WILL BE TAPPING INTO UNSEASONABLY HIGH PRECIPITABLE WATER VALUES OF ALMOST 2 INCHES IN THE GULF...THIS WILL ALLOW A WIDESPREAD AREA OF RAIN TO DEVELOP TONIGHT AND PERSIST INTO WEDNESDAY MORNING ACROSS NORTH TEXAS IN THE COLD SECTOR. WHILE RAINFALL RATES WILL LIKELY NOT EXCEED AN INCH PER HOUR...THE CONTINUOUS RAINS SHOULD HELP GENERATE EXCESSIVE RUNOFF. HEAVY RAIN EVENTS IN THE COLD SEASON TEND TO PRODUCE MORE RUNOFF THAN IN THE WARM SEASON. MOST VEGETATION IS DORMANT AND THEREFORE IT DOES NOT TAKE MUCH OF THE RAIN WATER OUT OF THE SOILS. WE ARE OUTLOOKED IN SLIGHT RISK FOR EXCESSIVE RAINFALL BY HPC AND HAVE ISSUED A FLASH FLOOD WATCH FOR AREAS WHERE WE EXPECT 2 TO 4 INCHES OF RAIN. THE METROPLEX IS ON THE EDGE OR JUST NORTHWEST OF THE HEAVY RAIN AXIS BUT WE BROUGHT THE WATCH INTO TARRANT/DALLAS/COLLIN COUNTIES BECAUSE THE URBANIZATION IS MORE SENSITIVE TO HEAVY RAINFALL. CONCERNING THE SEVERE WEATHER THREAT...A LINE OF STORMS SHOULD FORM IN SOUTH CENTRAL TEXAS THIS EVENING AND MOVE RATHER SLOWLY TO THE E/NE INTO OUR FAR SOUTH/SOUTHEAST ZONES AFTER 3 AM. ALTHOUGH THE WARM SECTOR DOES MAKE IT INTO THE SOUTHEAST ZONES AHEAD OF THE LINE...IT IS AT THE COOLEST TIME OF THE DAY. THIS WILL LIKELY LIMIT SURFACE BASED CAPE TO LESS THAN 100 J/KG IF ANYTHING AT ALL. BECAUSE SHEAR WILL BE HIGH...WE WILL HAVE TO MONITOR THIS CLOSELY...BUT AT THIS TIME THE SEVERE WEATHER THREAT LOOKS MORE CONDITIONAL THAN PREVIOUS FORECASTS WHICH HAD THE LINE MOVING IN DURING THE WARMER AFTERNOON HOURS. PASSAGE OF THE SURFACE TROUGH WILL BE SUCCEEDED BY DRY SLOT ALOFT WHICH SHOULD END MOST OF THE RAIN FROM WEST TO EAST DURING THE DAY WEDNESDAY. A FEW ELEVATED SHOWERS WILL REMAIN POSSIBLE WEDNESDAY EVENING BUT HAVE LOWERED POPS DUE TO THE FASTER TIMING. SOME WRAP AROUND CLOUDS WILL AFFECT THE NW ZONES THURSDAY...BUT OTHERWISE GENERALLY FAIR WEATHER WITH WARMER TEMPS DUE TO SW WINDS. FRIDAY WILL BE SUNNY AND WARMER WITH HIGHS NEAR 70. THE NEXT FRONT WILL ARRIVE SATURDAY AND BRING A SLIGHT CHANCE OF CONVECTION OVER THE EASTERN HALF OF THE AREA. TEMPS WILL COOL INTO THE 30S FOR LOWS SAT NIGHT...WITH THE UPPER LEVEL PATTERN FAVORABLE FOR SEVERAL DAYS OF COLD ADVECTION INTO NEXT WEEK. HIGH TEMPS WILL BE CHILLY SUNDAY INTO MID WEEK...GENERALLY IN THE LOW-MID 40S. GFS HAS BACKED OFF ON PRECIPITATION SUNDAY WHICH IS WHAT THE OTHER MODELS WERE FORECASTING...HOWEVER THERE IS A LITTLE MORE EVIDENCE THAT WE WILL CONTEND WITH POSSIBLE WINTRY PRECIPITATION FOR THE MIDDLE OF NEXT WEEK WHEN THE UPPER LEVEL PATTERN BECOMES MORE FAVORABLE. TR.92 && .CLIMATE... IN THE DALLAS/FORT WORTH METROPLEX...24-HOUR RAINFALL (MIDDAY TODAY TO MIDDAY WEDNESDAY) MAY REACH 3 INCHES. WHEN WAS THE LAST TIME DFW AIRPORT SAW THAT MUCH PRECIPITATION IN A 24 HOUR PERIOD? APRIL 8, 2012 (EASTER SUNDAY) - 2.23 MARCH 19-20, 2012 - 4.04 JANUARY 24-25, 2012 - 4.27 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 51 47 56 46 60 / 100 100 100 50 10 WACO, TX 52 49 57 45 64 / 100 100 100 30 10 PARIS, TX 52 47 57 51 60 / 90 100 100 80 10 DENTON, TX 50 45 54 45 59 / 100 100 90 60 10 MCKINNEY, TX 51 47 56 47 59 / 100 100 100 60 10 DALLAS, TX 51 47 56 46 60 / 100 100 100 50 10 TERRELL, TX 52 49 57 50 61 / 100 100 100 60 10 CORSICANA, TX 53 51 58 49 63 / 100 100 100 40 10 TEMPLE, TX 53 49 58 45 65 / 100 100 100 30 10 MINERAL WELLS, TX 48 44 54 42 60 / 90 100 80 50 10 && .FWD WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH FROM 6 PM CST THIS EVENING THROUGH WEDNESDAY AFTERNOON FOR TXZ094-095-104>107-118>123-133>135-145>148-158>162- 174-175. && $$