Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 040721 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 315 AM EDT MON MAY 4 2015 .SYNOPSIS....SYNOPSIS... HIGH PRESSURE OFF THE MID ATLANTIC COAST WILL EXTEND INTO THE REGION THROUGH MID WEEK. AN AREA OF LOW PRESSURE WILL FORM NEAR THE BAHAMAS DURING THE MIDDLE OF THE WEEK AND MOVE SLOWLY NORTH TOWARD THE SOUTHEAST COAST. && .NEAR TERM /TODAY/...
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AS OF 300 AM MONDAY... LATEST SURFACE ANALYSIS SHOWS HIGH PRESSURE CENTERED JUST OFF THE CAROLINA COAST WITH A LIGHT SOUTHERLY SURFACE FLOW ACROSS CENTRAL NC. WATER VAPOR IMAGERY SHOWS A SHORT WAVE TROUGH LOCATED OVER SOUTHWESTERN VA EARLY THIS MORNING DRIFTING SLOWLY SOUTHEAST. THE WEAK VORTEX HAS VERY LITTLE MOISTURE TO WORK WITH AT MID LEVELS ATOP A DRY AND INCREASINGLY WELL MIXED BOUNDARY LAYER TODAY. THE RESULT SHOULD BE MOSTLY SUNNY SKIES THIS MORNING THAT GIVE WAY TO PARTLY AND PERHAPS BRIEFLY OCCASIONALLY MOSTLY CLOUDY SKIES THIS AFTERNOON. THE HIGH-BASED CUMULUS FIELD WILL BE THICKEST ACROSS THE WESTERN PIEDMONT AND TRIAD. GUIDANCE INCLUDING SOME HIGH RES CONVECTION ALLOWING MODELS SUGGEST A FEW SHOWERS ACROSS THE MOUNTAINS TODAY. THE SAME GUIDANCE WAS A LITTLE TOO BULLISH ON THIS POTENTIAL FOR SUNDAY WITH VERY LITTLE IF ANY SHOWERS DEVELOPING. SO HAVE DECIDED TO HOLD ONTO THE SLIGHT CHANCE OF SHOWERS ACROSS THE FAR WESTERN ZONES NEAR THE YADKIN VALLEY AS A FEW SHOWERS MAY DRIFT EAST INTO THESE AREAS LATE IN THE DAY BEFORE DISSIPATING. HIGHS TODAY SHOULD BE A COUPLE OF DEGREES WARMER THAN ON SUNDAY GIVEN LOW LEVEL THICKNESS VALUES THAT START OFF 5-10M WARMER. WILL FORECAST HIGHS OF 79 NORTHWEST TO 83 SOUTHEAST. -BLAES
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&& .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
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AS OF 315 AM MONDAY... GENERALLY FAIR WEATHER IS EXPECTED THROUGH THE PERIOD AS SURFACE HIGH PRESSURE EXTENDS INTO THE AREA FROM THE ATLANTIC AND WEAK RIDGING DEVELOPS OVER THE REGION. THE MAIN FORECAST PROBLEM IS ASSOCIATED WITH THE SCATTERED DIURNAL CONVECTION THAT WILL LIKELY DEVELOP ACROSS THE MOUNTAINS AGAIN ON TUESDAY AFTERNOON. WHILE THE MIXED LAYER TUESDAY AFTERNOON IS NOT AS DEEP AS TODAY AND BOUNDARY LAYER MOISTURE INCREASES SLIGHTLY...STILL BELIEVE THE POTENTIAL FOR MOUNTAIN CONVECTION REACHING CENTRAL NC IS LIMITED. THE FLOW THROUGH THE CLOUD DEPTH IS WEAKER AND MORE NORTHERLY SUGGESTING CONVECTION MAY HAVE A HARD TIME PUSHING EAST AND IN FACT MAIN DRIFT SOUTH OR REMAIN ANCHORED TO THE TERRAIN. WITH THIS IN MIND WILL OMIT POPS FOR OUR WESTERN ZONES FOR TUESDAY AFTERNOON. EXPECT MAINLY CLEAR SKIES MONDAY NIGHT WITH PARTLY CLOUDY SKIES ON TUESDAY. MAINLY CLEAR SKIES ARE EXPECTED AGAIN TUESDAY NIGHT ALTHOUGH THE NAM AND A FEW SREF MEMBERS SUGGEST SOME SHALLOW STRATUS MAY APPROACH THE SANDHILLS AND SOUTHERN COASTAL PLAIN TOWARD DAYBREAK WEDNESDAY. LOWS ON TUESDAY MORNING WILL RANGE IN THE LOWER TO MID 50S WITH HIGHS AGAIN IN THE 79-84 RANGE. LOWS TUESDAY NIGHT WILL RANGE IN THE MID TO UPPER 50S. -BLAES
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&& .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 220 AM MONDAY... ...MID TO LATE WEEK FORECAST STILL CLOUDED BY POTENTIAL FOR COASTAL LOW DEVELOPMENT... THERE IS HIGH CONFIDENCE IN THE EXPECTED TROUGH OVER THE SOUTHWESTERN UNITED STATES THIS WEEK... WITH RIDGING OVER THE EASTERN STATES... WITH THE POTENTIAL FOR THE CUT OFF LOW DEVELOPMENT OFFSHORE OF THE SOUTH ATLANTIC COAST. THE LATEST MODEL GUIDANCE CONTINUED TO INDICATE A COUPLE OF CAMPS STILL EXIST ON THE POTENTIAL LOW PRESSURE DEVELOPMENT OFF THE SOUTHEAST COAST. THE TRENDS OF RECENT GFS RUNS AND ENSEMBLE MEANS ALONG WITH THE GEFS/ECENS/CANADIAN ALL FAVOR AT LEAST A MORE WESTWARD POSITION OF THE LOW PRESSURE... WHILE AT LEAST THE 12Z/03 ECMWF/CANADIAN GLOBAL/UKMET LIE FARTHER EAST. THE LATEST OPERATIONAL GFS ACTUALLY PULLS THE LOW PRESSURE WELL WESTWARD AND INLAND OVER SC LATE THURSDAY INTO FRIDAY. HPC CONTINUED TO FAVOR USING THE ENSEMBLES WHICH WOULD BE A COMPROMISE SOLUTION AND KEEPING THE LOW PRESSURE OFF THE SC COAST. THE HURRICANE CENTER IS MONITORING AND HAS INDICATED THAT THE SYSTEM... IF IT DEVELOPS... MAY HAVE SUBTROPICAL CHARACTERISTICS. IT APPEARS THAT THE FARTHER NORTH THE SYSTEM TRACKS... THE LESS IN THE WAY OF TROPICAL SUPPORT IT WOULD HAVE GIVEN THE LESS THAN FAVORABLE WATER TEMPERATURES OFF THE CAROLINA COAST. OBVIOUSLY... THE ULTIMATE DEVELOPMENT AND SUBSEQUENT TRACK OF THE SYSTEM WILL GO A GREAT WAY IN DETERMINING IF OUR REGION WILL GET SIGNIFICANT RAINFALL THIS PERIOD GIVEN THE UPPER RIDGING IN PLACE. FINALLY... THE EAST COAST UPPER RIDGE AND POSSIBLY THE MID/UPPER SOUTHEASTERN US CUT OFF LOW MAY FINALLY GET A BIT OF A KICKER LATE IN THE WEEKEND AS THE TROUGH OUT WEST FINALLY PULLS OUT INTO THE PLAINS AND MIDWEST INCREASING OUR SW FLOW ALOFT. FOR NOW... WE WILL MAINTAIN A MOSTLY DRY FORECAST WITH A SLIGHT CHANCE OF MAINLY AFTERNOON AND EARLY EVENING SHOWERS AND THUNDERSTORMS THURSDAY THROUGH THE WEEKEND GIVEN THE UNCERTAINTY. REGARDLESS... WITH THE UPPER RIDGE IN PLACE... TEMPERATURES WILL BE MUCH WARMER THIS WEEK. LOWS LATER IN THE WEEK SHOULD BE AT OR ABOVE 60 OR EVEN 65. HIGHS GENERALLY 80-85. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 200 AM MONDAY... MODERATE CONFIDENCE OF VFR CONDITIONS THROUGH THE 24 HOUR TAF PERIOD AS HIGH PRESSURE CENTERED TO OUR SOUTH SLOWLY SLIPS OFF THE COAST BUT EXTENDS INTO THE REGION THROUGH TUESDAY. AN UPPER LEVEL SHORT WAVE TROUGH WILL SLOWLY MOVE ACROSS CENTRAL NC TODAY AND OFF THE COAST TONIGHT. WHILE A FEW SHOWERS ARE LIKELY TO DEVELOP ACROSS MOUNTAINS TODAY AND DRIFT EAST...THE PROBABILITY OF ANY OF THESE SHOWERS REACHING THE TRIAD REMAINS VERY SMALL AND WILL BE OMITTED FROM THE TAF. THE ONLY OTHER POTENTIALLY ADVERSE WEATHER COULD BE A BRIEF PERIOD OF MVFR RADIATION FOG AT KRWI TOWARD DAYBREAK TODAY. OTHERWISE SCT CLOUDS AT 6-10KFT THIS MORNING WILL GIVE WAY TO A MORE PROMINENT CLOUD DECK OF SCT-BKN CUMULUS THIS AFTERNOON AT AROUND 6-8KFT. A LIGHT MAINLY SOUTHERLY WIND FROM 190- 220 DEGREES AT 5-10 KTS IS EXPECTED TODAY. OUTLOOK...GENERALLY FAIR WEATHER IS EXPECTED FOR LATE TONIGHT INTO TUESDAY NIGHT WITH SHOWERS DEVELOPING ACROSS THE MOUNTAINS TUESDAY AND WEDNESDAY AFTERNOONS. AN ONSHORE FLOW WILL INCREASE AND PERSIST DURING THE MID AND LATE WEEK AS LOW PRESSURE DEVELOPS NEAR THE BAHAMAS AND DRIFTS NORTH. A WEAK FRONT WILL ALSO DROP INTO THE REGION LATE WEDNESDAY INTO THURSDAY. MOISTURE IS EXPECTED TO INCREASE DURING THE WEEK ALONG WITH THE THREAT OF EARLY MORNING STRATUS/FOG. THERE IS THE POTENTIAL FOR MORE WIDESPREAD ADVERSE AVIATION CONDITIONS ASSOCIATED WITH THE COASTAL STORM SYSTEM TO ARRIVE LATE IN THE WORK WEEK. -BLAES && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...WSS SHORT TERM...22 LONG TERM...BADGETT AVIATION...BLAES

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