Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 290558 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 158 AM EDT FRI AUG 29 2014 .SYNOPSIS...A SLOW MOVING BACK DOOR COLD FRONT IN SOUTHERN VIRGINIA WILL STALL OUT NEAR OR JUST SOUTH OF THE NORTH CAROLINA BORDER TODAY. THE FRONT WILL GRADUALLY DISSIPATE OVER THE WEEKEND AS A LIGHT SOUTHERLY RETURN FLOW DEVELOPS ACROSS THE REGION. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1015 PM THURSDAY... THE BACKDOOR SEGMENT OF THE COLD FRONT ORIENTED FROM NW TO SE ACROSS SOUTH-CENTRAL VA HAS MAINTAINED A BAND OF WEAK CONVECTION CENTERED NEAR FARMVILLE...VA FOR THE PAST SEVERAL HOURS. A PRECEDING...PRE- FRONTAL TROUGH DRAPED ACROSS CENTRAL NC HAS BEEN DEVOID OF ANY SUCH ACTIVITY...HOWEVER...DESPITE A RIBBON OF LOW-MID LEVEL MOISTURE CONVERGENCE AND WEAK AND SEEMINGLY UNINHIBITED ML INSTABILITY PER 00Z GSO AND MHX RAOB DATA. RECENT RUNS OF THE HRRR CONTINUE TO SUGGEST THE CONVECTION OVER SOUTH-CENTRAL VA WILL DRIFT SOUTH ACROSS THE NORTHEAST PIEDMONT AND NORTHERN COASTAL PLAIN...AND SUCH A SCENARIO SEEMS PLAUSIBLE GIVEN THE ENVIRONMENT DESCRIBED ABOVE. WILL CONSEQUENTLY MAINTAIN A SLIGHT-SMALL CHANCE OF A SHOWER OR STORM THERE OVERNIGHT. THE OTHER...AND HIGHER PROBABILITY...CONCERNS INCLUDE THE DEVELOPMENT OF AREAS OF FOG...OWING TO SAID LOW LEVEL MOISTURE POOLING ALONG THE PRE-FRONTAL TROUGH AXIS...AND LOW CLOUDS IN POST-FRONTAL NE LOW LEVEL FLOW ONCE THE FRONT SETTLES SOUTH INTO THE SANDHILLS AND SOUTHERN PIEDMONT BY EARLY FRI. IN FACT...A LOW OVERCAST IS APT TO DEVELOP GENERALLY ALONG AND NORTH OF HWY 64 VERY LATE TONIGHT THROUGH EARLY FRI. IF THE LOW CLOUDS INDEED MATERIALIZE...THEIR DISPERSION THROUGHOUT THE DAY FRI WOULD BE SLOW OWING A TRAPPING FRONTAL INVERSION BEHIND THE SOUTHWARD-SETTLING FRONT...WHICH COULD IMPACT HIGH TEMPS FRI. LOWS TONIGHT IN THE MID 60S TO LOW 70S. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 200 PM THURSDAY... FRIDAY AND FRIDAY NIGHT: THE UPPER LEVEL RIDGE WILL AMPLIFY OVER THE MID-ATLANTIC ON FRIDAY. AT THE SURFACE...THE FRONT WILL BE STALLED IN THE VICINITY OF THE NC/VA BORDER DURING THE DAY BEFORE SLOWLY RETREATING TO THE NE OVERNIGHT. MUCH OF THE WEATHER WILL DEPEND ON THE LOCATION OF THE FRONTAL BOUNDARY THROUGHOUT THE DAY. THE LOWER TEMPS WILL BE ALONG AND NORTH OF THE FRONT...WITH HIGHER HIGHS ACROSS THE SOUTH. ANY CONVECTION THAT DEVELOPS WILL BE MAINLY ALONG AND SOUTH OF THE FRONT...BUT EXPECT COVERAGE TO BE ISOLATED AT BEST AND CONFIDENCE THAT IT WILL DEVELOP IS NOT TERRIBLY HIGH AT THIS TIME. CONTINUED MID LEVEL MOISTURE ADVECTION SHOULD RESULT IN CLOUDY CONDITIONS THROUGH A GOOD PART OF THE DAY. NORTHEASTERLY WINDS ALONG AND NORTH OF THE FRONT AND SOUTHWESTERLY SOUTH OF IT DURING THE DAY/EVENING SHOULD BECOME GENERALLY SOUTHEASTERLY ACROSS THE AREA OVERNIGHT. HIGHS EXPECTED TO RANGE FROM THE MID 80S NORTH TO LOW 90S SOUTH. LOWS IN THE UPPER 80S TO AROUND 70 DEGREES. -KC SATURDAY AND SATURDAY NIGHT: NORTH CAROLINA WILL STILL BE UNDER THE INFLUENCE OF A STRONG UPPER LEVEL RIDGE AND AN EXITING SURFACE HIGH PRESSURE TO THE NORTHEAST. THIS WILL KEEP WEATHER DRY AND SETTLED ON SATURDAY AND SATURDAY AFTERNOON. CONDITIONS WILL BE STABLE AND A SLIGHT DECREASE IN MOISTURE MAY HELP HIGH TEMPERATURES TO REACH THE LOWER 90S IN MOST LOCATIONS WITH UPPER 80S ACROSS THE NORTHERN COUNTIES. WINDS WILL BE OUT OF THE SOUTH AT AROUND 5 KTS GUSTING TO 10 KTS. THE HIGH WILL CONTINUE TO MOVE OFFSHORE SATURDAY NIGHT...ALLOWING MOISTURE TRANSPORT OUT OF THE GULF OF MEXICO TO INCREASE AS A DISSIPATING LOW PRESSURE SYSTEM MOVES EASTWARD OUT OF THE NORTHERN PLAINS AND INTO THE GREAT LAKES REGION. THIS WILL SET THE STAGE FOR A MORE UNSETTLED PATTERN BEGINNING ON SUNDAY. LOWS SATURDAY NIGHT UPPER 60S TO LOWER 70S. -ELLIS && .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...MWS SHORT TERM...KC/ELLIS LONG TERM...ELLIS AVIATION...VINCENT

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