Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 290628 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 228 AM EDT FRI AUG 29 2014 .SYNOPSIS...
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A SLOW MOVING BACK DOOR COLD FRONT WILL STALL OUT NEAR OR JUST SOUTH OF THE NORTH CAROLINA AND VIRGINIA BORDER TODAY. THE FRONT WILL GRADUALLY DISSIPATE OVER THE WEEKEND AS A LIGHT SOUTHERLY RETURN FLOW DEVELOPS ACROSS THE REGION.
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&& .NEAR TERM /TODAY AND TONIGHT/...
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AS OF 220 AM FRIDAY... OVERVIEW: AN UPPER LEVEL RIDGE CENTERED OVER THE SOUTHEAST STATES WILL EXTEND N/NE INTO THE MID-ATLANTIC TODAY/TONIGHT. A WEST-EAST ORIENTED BACK DOOR COLD FRONT LOCATED IN SOUTHERN VA AT 06Z THIS MORNING IS EXPECTED TO MAKE LITTLE ADDITIONAL PROGRESS PRIOR TO STALLING OUT ALONG OR JUST SOUTH OF THE NC/VA BORDER TODAY...UNLESS THE POSITION/ORIENTATION OF THE BOUNDARY IS AUGMENTED BY CONVECTION. BELOW AVERAGE CONFIDENCE IN THE FORECAST THROUGH TONIGHT. MODEL GUIDANCE CONTINUES TO VARY WITH THE PRECISE POSITION AND ORIENTATION OF THE STALLED FRONT TODAY...IN ADDITION TO THE PRECISE ORIENTATION OF THE LOW-LEVEL HEIGHT GRADIENT. AS A RESULT... POSSIBLE SOLUTIONS RANGE FROM A HYBRID COLD AIR DAMMING WEDGE AND ELEVATED CONVECTION DEVELOPING BETWEEN 12-18Z TODAY NORTH OF HWY 64 TO NO WEDGE DEVELOPMENT AND A SOMEWHAT TYPICAL POTENTIAL FOR ISOLD TO SCT SFC- BASED CONVECTION. GIVEN THE SUBTLE NATURE OF THE PATTERN IN PLACE AND THAT CONVECTION COULD LARGELY DICTATE THE EVOLUTION OF THE LOW- LEVEL PATTERN...WILL LEAVE THE FORECAST ROUGHLY AS-IS WITH A SLIGHT TO LOW CHANCE (20-30%) OF CONVECTION AND HIGHS RANGING FROM THE MID 80S NORTH TO LOWER 90S SOUTH. LOWS TONIGHT NEAR 70F. -VINCENT
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&& .SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
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AS OF 220 AM FRIDAY... CENTRAL NC WILL REMAIN UNDER THE INFLUENCE OF AN UPPER LEVEL RIDGE SAT/SAT NIGHT AS THE CENTER OF THE RIDGE CURRENTLY OVER THE SOUTHEAST STATES SHIFTS SLIGHTLY EAST TOWARD THE COAST. THE LINGERING FRONTAL ZONE OVER PORTIONS OF CENTRAL NC SHOULD WASH OUT DURING THE DAY AS A LIGHT S/SE RETURN FLOW DEVELOPS ACROSS THE REGION. GIVEN A PROTOTYPICAL SUMMER PATTERN...EXPECT SLIGHTLY ABOVE NORMAL TEMPS IN THE LOWER 90S WITH A SLIGHT CHANCE OF CONVECTION DURING THE AFT AND EARLY EVE HOURS AND NEAR NORMAL LOWS SAT NIGHT IN THE UPPER 60S TO LOWER 70S. -VINCENT
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 245 PM THURSDAY... SUNDAY THROUGH TUESDAY NIGHT: A MORE UNSETTLED PERIOD OF WEATHER WILL BEGIN ON SUNDAY WITH HIGH PRESSURE OFFSHORE SETTING UP A RETURN FLOW REGIME OVER CENTRAL NC THAT WILL TRANSPORT MOISTURE INTO THE AREA FROM THE GULF OF MEXICO AND SOUTHWESTERN ATLANTIC. AS PW VALUES CREEP UP OVER TWO INCHES THE CHANCES FOR CONVECTION WILL INCREASE...MAINLY DRIVEN BY INSTABILITY DURING THE DIURNALLY FAVORABLE TIMES AS SHEAR WILL REMAIN VERY WEAK. HIGH TEMPERATURES ARE EXPECTED TO RISE INTO THE LOWER 90S EACH DAY WITH LOWS IN THE LOWER 70S. WEDNESDAY AND THURSDAY: A MORE DEFINED FRONTAL SYSTEM WILL MOVE IN ON WEDNESDAY AS LOW PRESSURE MOVES THROUGH SOUTHERN QUEBEC AND A STRONG SURFACE HIGH BUILDS IN OVER THE GREAT LAKES AND EXTENDING DOWN INTO THE OHIO VALLEY. WITH THE LOW RAPIDLY MOVING OFF TO THE NORTHEAST...FORCING ALONG THE ATTENDANT COLD FRONT WILL REMAIN WEAK AS SHOWN BY SMALL STRAIGHT HODOGRAPHS THROUGH THE LOWEST 6KM ON MODEL FORECAST SOUNDINGS. TIMING OF THE FRONT AND ASSOCIATED PRECIPIATION IS IN QUESTION AT THIS TIME WITH MODELS HINTING AT A LATE WEDNESDAY/EARLY THURSDAY ARRIVAL AND THEN STALLING OUT SOMEWHERE OVER THE AREA FOR LATE WEEK. MOST CONVECTIVE ACTIVITY WILL REMAIN DIURNAL WITH THE SLIGHT CHANCES OVERNIGHT. TEMPERATURES SLIGHTLY COOLER WITH MORE ANTICIPATED CLOUD COVER AND SLIGHT AIRMASS CHANGE. UPPER 80S TO NEAR 90 FOR HIGHS WITH LOWS UPPER 60S TO NEAR 70 DEGREES. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 150 AM FRIDAY... 24-HR TAF PERIOD: BELOW AVERAGE CONFIDENCE IN THE FORECAST THROUGH TONIGHT. A BACK DOOR COLD FRONT ORIENTED WEST-EAST ACROSS SOUTHERN VA AT 06Z WILL MOVE SLOWLY SOUTH TOWARD THE NC BORDER TODAY... EVENTUALLY STALLING OUT NEAR OR JUST SOUTH OF THE BORDER ACROSS THE NORTHERN PIEDMONT. MODEL GUIDANCE CONTINUES TO VARY CONSIDERABLY WITH REGARD TO CEILINGS AND PRECIP CHANCES TODAY INTO TONIGHT. THE 00Z NAM INDICATES A HYBRID COLD AIR DAMMING WEDGE WITH MVFR/IFR CEILINGS AND ELEVATED SHOWER ACTIVITY DEVELOPING BETWEEN 12-18Z AT ALL OF THE NORTHERN TERMINALS (INT/GSO/RDU/RWI)...WHILE THE GFS INDICATES VFR CONDITIONS PREVAILING OUTSIDE OF MVFR CONDITIONS ASSOC/W ISOLD SFC-BASED CONVECTION. WITH LITTLE INDICATION ONE WAY OR THE OTHER...WILL SPLIT THE DIFFERENCE AND INTRODUCE A TEMPO GROUP FOR BKN015 BETWEEN 12-16Z EVERYWHERE EXCEPT THE FAY TERMINAL. LOOKING AHEAD: EXPECT A NEAR CLIMATOLOGICAL PATTERN THROUGH EARLY NEXT WEEK WITH A SLIGHT CHANCE OF AFTERNOON/EVENING CONVECTION AND A POTENTIAL FOR EARLY MORNING FOG/STRATUS. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...VINCENT LONG TERM...ELLIS AVIATION...VINCENT

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