Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 191415 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1010 AM EDT TUE AUG 19 2014 .SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES WILL CROSS THE REGION THROUGH MID-WEEK IN ASSOCIATION WITH A NORTHWEST FLOW ALOFT. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1010 AM TUESDAY... VISIBLE SATELLITE IMAGERY SHOWS A FAIRLY WELL DEFINED CIRCULATION OVER THE TIDEWATER REGION IN THE WAKE OF THE SHORTWAVE OFF THE COAST. NORTHERLY LOW-LEVEL FLOW BEHIND THIS WEAK LOW IS HELPING TO PUSH A LARGE AREA OF STRATUS SOUTH ACROSS THE NORTHERN PIEDMONT AND NORTHERN COASTAL PLAIN. THE STRATUS APPEARS TO BE LIFTING ON THE SOUTHERN EDGES AS WE HEAT UP...SO AREAS SOUTH OF RALEIGH TO GOLDSBORO SHOULD STAY MOSTLY SUNNY THIS MORNING. DESPITE THE SLOWLY LIFTING STRATUS..STILL EXPECT FULL HEATING BY THE AFTERNOON FOR ALL AREAS AND HIGHS IN THE UPPER 80S AND LOWER 90S. UPSTREAM...WATER VAPOR INDICATES A DISTURBANCE OVER UPSTATE SC...WHICH WILL PROPAGATE ALONG THE NC/SC BORDER THIS MORNING AND BE POSITIONED SOUTH OF FAYETTEVILLE BY 18Z. THIS SHOULD FAVOR THE SOUTHERN COASTAL PLAIN FOR BEST POPS THIS AFTERNOON. THERMODYNAMICALLY...LITTLE HAS CHANGED COMPARED TO MONDAY...EXCEPT FOR SLIGHTLY WARMER H7-H5 TEMPS...WHICH MAY EXPLAIN WHY MODELS INDICATE ONLY 1000-1500 J/KG ACROSS THE SOUTHERN CWA. SHEAR WILL BE MUCH WEAKER TODAY...ESSENTIALLY 20KT OR LESS AND WEAKEST TO THE SOUTH. MOST OF THE CAMS SHOW ONLY SCATTERED CONVECTION...ALSO FAVORING THE SOUTH...ALONG WITH SOME ACTIVITY MOVING OFF THE HIGHER TERRAIN TO THE SOUTHEAST AND INTO THE WESTERN PIEDMONT. WITH ALL OF THIS IN MIND..WILL ONLY BE MAKING SOME MINOR CHANGES TO THE FORECAST...MAINLY TO UPDATE FOR THE STRATUS AND FOCUS POPS A LITTLE MORE TOWARD THE SOUTHERN PIEDMONT. SEEING A LARGE AREA OF STRATUS CONTINUE TO DRIFT SOUTH ACROSS THE NORTHERN PIEDMONT AND NORTHERN COASTAL PLAIN DUE TO A REMNANT CIRCULATION OVER THE TIDEWATER REGION. -BLS MUCH LIKE THIS PAST EVENING...PERIOD OF SYNOPTIC SCALE SUBSIDENCE TUESDAY EVENING/NIGHT IN THE WAKE OF THE UPPER WAVE MOVING OFF THE SE COAST SHOULD RESULT IN MOSTLY DRY CONDITIONS OVERNIGHT. HIGHS IN THE UPPER 80S TO LOWER 90S. LOWS TONIGHT IN THE UPPER 60S TO LOWER 70S. -CBL && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 300 AM TUESDAY... THE POTENTIAL FOR WEAK SHORTWAVE DISTURBANCES IN THE LOW-AMPLITUDE W- NW FLOW ALOFT... BETWEEN AN UPPER LEVEL RIDGE BUILDING FROM THE WESTERN GULF OF MEXICO INTO THE NRN PLAINS AND UPPER LEVEL LOW OVER THE GREAT LAKES WILL CONTINUE TO POSE AT LEAST AN ISOLATED CONVECTIVE CHANCES FOR WEDNESDAY. HIGHS IN THE 89 TO 94. LOWS IN THE UPPER 60S TO LOWER 70S. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 300 AM TUESDAY... THE LONG TERM PERIOD WILL BE CHARACTERIZED BY A BUILDING UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY WITH A CLOSED UPPER LOW OFF THE NORTHEAST COAST...LEAVING CENTRAL NC UNDER A NORTHWESTERLY UPPER FLOW REGIME. DIFFERENCES REMAIN AMONG THE MODELS WITH RESPECT TO THE AMPLITUDE OF THE UPPER AIR PATTERN...ESPECIALLY BY THE WEEKEND (ALTHOUGH THERE APPEARS TO BE SLIGHTLY BETTER OVERALL AGREEMENT TONIGHT). AS SUCH...PRECISE TIMING OF ANY DISTURBANCES ALOFT THIS FAR OUT IS NEARLY IMPOSSIBLE AND THEREFORE CONFIDENCE IN THE EXACT DETAILS OF PRECIP CHANCES ARE RATHER LOW. TO BEGIN ON THURSDAY...A SHORTWAVE TROUGH WILL BE TRACKING ACROSS THE EASTERN GREAT LAKES...EVENTUALLY TRANSITIONING INTO A CLOSED LOW/DEEP TROUGH JUST OFF THE EAST COAST THROUGH EARLY NEXT WEEK. THIS SHORTWAVE TROUGH IS PROGGED TO PUSH A BACKDOOR COLD FRONT THROUGH THE AREA THURSDAY NIGHT INTO FRIDAY. THIS SHOULD LEAD TO SOLID CHANCE POPS. THEN MODELS REALLY DIVERGE...WITH THE ECMWF SHUNTING THE FRONT WELL TO OUR SOUTH...ALLOWING COOLER AND DRIER AIR TO FILTER IN AS A HIGH BUILDS DOWN THE MOUNTAINS FOR THE LATTER PART OF THE WEEKEND AND INTO EARLY NEXT WEEK AND RESULTANTLY DRYING US OUT. THE GFS IS WEAKER WITH THE HIGH OVER OUR AREA...WITH A VERY MOIST AIR MASS PERSISTING (PWAT VALUES HOVERING NEAR 2 INCHES). THEREFORE... IT IS THE WETTER SOLUTION GIVEN THE SERIES OF DISTURBANCES ALOFT LIKELY TO CROSS THE AREA IN THE NORTHWESTERLY UPPER LEVEL FLOW. WILL KEEP POPS IN THROUGH THE FORECAST PERIOD... BUT WILL SHOW A DOWNWARD TREND FOR THE WEEKEND/EARLY NEXT WEEK. TEMPS ON THURSDAY ARE EXPECTED TO BE IN THE LOW TO MID 90S...WITH SLIGHTLY "COOLER" TEMPS FOR THE REMAINDER OF THE PERIOD GIVEN EITHER THE COOLER DRIER AIR (PER THE ECMWF) OR THE INCREASED CLOUDS AND PRECIP CHANCES (PER THE GFS)...WITH MAINLY 80S EXPECTED OVER THE WEEKEND AND EARLY NEXT WEEK. OVERNIGHT LOWS WILL GENERALLY IN THE UPPER 60S TO LOWER 70S THROUGHOUT THE PERIOD. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 730 AM TUESDAY... 24-HR TAF PERIOD: EARLY MORNING PATCHY FOG AND STRATUS SHOULD IMPROVE TO VFR BY 14 TO 15Z. ISOLATED TO SCATTERED SHOWERS AND STORMS ARE EXPECTED THIS AFTERNOON AS ANOTHER UPPER LEVEL DISTURBANCES TRACKS THROUGH THE AREA. SOME OF THE MODEL GUIDANCE INDICATE THE HIGHEST PROBABILITY OF SHOWERS AND STORMS WILL BE ACROSS SOUTHERN PORTIONS OF CENTRAL NC. THUS... HAVE ONLY INCLUDED TEMPO GROUP FOR THUNDER AT KFAY FOR THE AFTERNOON. LOOKING AHEAD: EXPECT A CLIMATOLOGICAL POTENTIAL FOR AFT/EVE SHOWERS AND STORMS THROUGH MID TO LATE WEEK...ALONG WITH A POTENTIAL FOR FOG AND/OR LOW CEILINGS DURING THE EARLY MORNING HOURS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...CBL/BLS SHORT TERM...CBL LONG TERM...KRD AVIATION...CBL/VINCENT

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