Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 230614 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 214 AM EDT TUE SEP 23 2014 .SYNOPSIS...
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AN UPPER LEVEL LOW WILL STALL AND PERSIST OVER THE CAROLINAS THROUGH MID-WEEK.
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&& .NEAR TERM /TODAY AND TONIGHT/...
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AS OF 200 AM TUESDAY... OVERVIEW: A POTENT UPPER LEVEL LOW CENTERED OVER EAST-CENTRAL GA AT 06Z WILL TRACK INTO SC THIS MORNING...THEN STALL OUT OVER THE CAROLINAS THROUGH TONIGHT. SHORTWAVE ENERGY ROTATING AROUND THE UPPER LOW WILL AID IN CYCLOGENESIS IN VICINITY OF A COASTAL FRONT SITUATED ALONG OR JUST OFFSHORE THE SOUTHEAST COAST TONIGHT AS HIGH PRESSURE OVER THE MID-ATLANTIC EXTENDS SOUTHWARD THROUGH CENTRAL AND WESTERN PORTIONS OF THE CAROLINAS. PRECIPITATION: FORECAST UNCERTAINTY PERSISTS W/REGARD TO THE PRECISE EVOLUTION OF THE CUT-OFF LOW OVER THE REGION...ESPECIALLY W/REGARD TO THE TIMING/STRENGTH/LOCATION OF SHORTWAVE ENERGY ROTATING AROUND THE LOW AND THE INFLUENCE OF CONVECTIVE PRECIPITATION EXPECTED TO DEVELOP IN VICINITY OF THE COASTAL FRONT ALONG THE SOUTHEAST COAST TODAY/TONIGHT. THE LATEST 00Z GFS/NAM GUIDANCE INDICATE A POTENTIAL FOR ELEVATED CONVECTION UNDER THE COLD POOL ALOFT IN CENTRAL/WESTERN NC TODAY...IN ADDITION TO A POTENTIAL FOR ELEVATED CONVECTION ON THE COOL SIDE OF THE COASTAL FRONT IN THE SE COASTAL PLAIN...WITH THE BEST CHANCE LATE TONIGHT IN THE COASTAL PLAIN AS THE COASTAL FRONT SHARPENS AND EDGES CLOSER TO THE COAST IN ADVANCE OF A DEVELOPING WAVE OF LOW PRESSURE. UNTIL ADDITIONAL GUIDANCE AND OBSERVATIONAL DATA CAN BE ASSESSED...WILL INDICATE PRECIPITATION CHANCES AS MENTIONED ABOVE. TEMPS: CHALLENGING TEMPERATURE FORECAST. BROKEN TO OVERCAST MID- LEVEL CEILINGS OVER THE BULK OF CENTRAL NC WILL INHIBIT INSOLATION AND KEEP TEMPS COOLER THAN YESTERDAY...THOUGH EXACTLY HOW COOL WILL HIGHLY DEPEND ON THE TIMING/LOCATION OF PRECIPITATION THAT DEVELOPS. IF THE GFS SOLUTION VERIFIES...I.E. ELEVATED PRECIPITATION INLAND OVER THE WESTERN PIEDMONT...TEMPS WOULD HAVE DIFFICULTY EXCEEDING THE 50S TODAY. HOWEVER...IF THE NAM SOLUTION VERIFIES...I.E. NO INLAND PRECIPITATION...TEMPS IN THE TRIAD WOULD RISE INTO THE UPPER 60S. AT THIS TIME WILL INDICATE HIGHS IN THE 60S OVER ALL OF CENTRAL NC. EXPECT RELATIVELY LITTLE DIURNAL VARIATION IN TEMPS WITH LOWS TONIGHT IN THE 50S TO LOWER 60S. -VINCENT
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 230 PM MONDAY... FORECAST CONFIDENCE REMAINS SOMEWHAT BELOW NORMAL FOR THE MIDDLE OF THE WEEK AS THERE CONTINUES TO BE SOME DISAGREEMENT AMONG THE MODELS...ALTHOUGH THERE IS SOME MODEL CONVERGENCE TOWARDS A MORE UNSETTLED PERIOD. THE LOW LEVEL FLOW AROUND THE HIGH WILL INCREASE AND BEGIN TO GRADUALLY TAKE ON MORE OF AN EAST OF NORTHERLY COMPONENT (AS HIGH PRESSURE SHIFTS OFF THE NORTHEAST COAST) ALLOWING MOISTURE TO RETURN TO THE AREA. IN ADDITION...MODELS CONTINUE TO HINT AT A WEAKNESS ALOFT AND ASSOCIATED INVERTED TROUGH DEVELOPING NEAR THE SOUTHEAST COAST (ALTHOUGH TO VARYING DEGREES AMONG THE MODELS). THIS WOULD INCREASE CLOUDS AND PRECIP CHANCES (ESPECIALLY ACROSS EASTERN NC). THE MORE CONSISTENT ECMWF SHOWS A CLOSED LOW ALOFT ACROSS THE SOUTHEAST WHICH IN TURN RESULTS IN A STRONGER INVERTED TROUGH AND THEREFORE MORE ENHANCED PRECIP/CLOUD COVER. THE GFS NOW ALSO SHOWS A CLOSED LOW ALOFT OVER THE AREA...BUT IT IS FURTHER OFFSHORE (AND MORE PROGRESSIVE) WITH THE INVERTED TROUGH...THUS IT IS STILL THE DRIER SOLUTION. WILL CONTINUE TO FOLLOW MORE CLOSELY TO THE MORE CONSISTENT ECMWF (AND EC ENSEMBLE MEAN). REGARDLESS...CLOUDY AND COOLER CONDITIONS WILL PERSIST... WITH RAIN CHANCES INCREASING (ESPECIALLY ACROSS THE EAST). HIGHS ARE EXPECTED TO STAY IN THE LOW TO MID 70S (WITH SOME UPPER 60S POSSIBLE) AND OVERNIGHT LOWS MOSTLY IN THE MID/UPPER 50S TO LOWER 60S. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 230 PM MONDAY... SOME DRYING IS EXPECTED BEGINNING FRIDAY...BUT ESPECIALLY INTO THE WEEKEND AS THE UPPER LOW FILLS IN WHILE RIDGING TRIES TO BUILD EAST. THIS WILL CAUSE THE INVERTED TROUGH TO WEAKEN/DISSIPATE. HOWEVER... WILL NOT REMOVE POPS ALTOGETHER AS THERE WILL BE STILL BE A WEAKNESS ALOFT OVER THE AREA AND MOISTURE WILL NOT DECREASE SIGNIFICANTLY. WITH THE ABOVE IN MIND...TEMPS WILL UNDERGO SOME MODERATION...AND ARE EXPECTED TO RETURN TO NEAR NORMAL VALUES. OUR NEXT SYSTEM MAY APPROACH THE AREA EARLY NEXT WEEK...BUT AS CAN BE EXPECTED (GIVEN THE LOW CONFIDENCE IN THE MEDIUM RANGE FORECAST)...THERE IS A LOT OF UNCERTAINTY IN THE EXTENDED RANGE. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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AS OF 200 AM TUESDAY... 24-HR TAF PERIOD: EXPECT VFR CONDITIONS TO PREVAIL THROUGH THE TAF PERIOD WITH CEILINGS GENERALLY NO LOWER THAN 5-8 KFT AND A NORTHEAST BREEZE AT 5-10 KT...EXCEPT 10-15 KT AT THE FAY TERMINAL LATER TODAY INTO TONIGHT AS THE MSLP GRADIENT TIGHTENS ALONG THE SOUTHEAST COAST. ANY CHANCE FOR SUB-VFR CONDITIONS SHOULD BE CONFINED TO THE FAY/RWI TERMINALS AT THE END OF THE TAF PERIOD WHEN PRECIPITATION AND MVFR CEILINGS MAY SPREAD INLAND IN ADVANCE OF A WAVE OF LOW PRESSURE TRACKING NE ALONG THE FRONTAL ZONE STALLED IN VICINITY OF THE SE COAST. LOOKING AHEAD: SUB-VFR CONDITIONS ASSOC/W RAIN WILL BE POSSIBLE AT THE RDU/FAY/RWI TERMINALS ON WEDNESDAY AS THE AFOREMENTIONED WAVE OF LOW PRESSURE TRACKS NORTHWARD ALONG THE MID-ATLANTIC COAST...THOUGH UNCERTAINTY PERSISTS WITH REGARD TO HOW FAR WEST PRECIPITATION WILL DEVELOP AND THE RELATIVE BEST CHANCE FOR SUB-VFR CONDITIONS WILL BE AT THE FAY/RWI TERMINALS. OTHERWISE...EXPECT VFR CONDITIONS TO PREVAIL THROUGH THE REMAINDER OF THE WEEK AS HIGH PRESSURE EXTENDS INTO THE CAROLINAS FROM THE NORTH. -VINCENT
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...KRD LONG TERM...KRD AVIATION...VINCENT

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