Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 030809 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 408 AM EDT MON AUG 3 2015 .SYNOPSIS... AN AREA OF LOW PRESSURE NEAR THE BIG BEND OF FL THIS MORNING WILL TRACK SLOWLY NORTHEAST IN THE VICINITY OF A NEARLY STATIONARY FRONT OVER THE SOUTHEASTERN US THROUGH TUE NIGHT. WEAK HIGH PRESSURE WILL OTHERWISE REMAIN SITUATED OVER THE SOUTHERN APPALACHIANS. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 345 AM MONDAY... MOIST SOUTHERLY FLOW ON THE NE PERIPHERY OF AN AREA OF LOW PRESSURE NEAR THE BIG BEND OF FL THIS MORNING WILL SUPPORT THE CONTINUED NORTHWARD DEVELOPMENT/EXPANSION OF AN AREA OF SCATTERED TO BROKEN MVFR RANGE/LOW CLOUDS INTO CENTRAL AND SOUTHEASTERN NC THIS MORNING. THE LOW CLOUDS ARE EXPECTED TO LIFT AND SCATTER TO PARTLY TO OCCASIONALLY MOSTLY CLOUDY OVER THE COASTAL PLAIN...PARTICULARLY THE SOUTHERN AND CENTRAL HALF...WHILE PARTLY TO MOSTLY SUNNY SKIES ARE EXPECTED ELSEWHERE. RICHER LOW LEVEL MOISTURE ALONG AND EAST OF A QUASI-STATIONARY FRONT OVER THE EASTERN PART OF THE STATE... CHARACTERIZED BY SURFACE DEWPOINT TEMPERATURES IN THE LOWER 70S...WILL ALSO SUPPORT SCATTERED SHOWERS AND STORMS OVER THE FAR EASTERN SANDHILLS AND SOUTHERN AN CENTRAL COASTAL PLAIN FROM LATE MORNING ONWARD. HIGH TEMPERATURES IN THE UPPER 80S TO MIDDLE 90S...COOLEST FROM CTZ TO GSB WHERE CLOUDS WILL BE MOST PREVALENT...AND WARMEST OVER THE SOUTHERN PIEDMONT AND SANDHILLS. GIVEN LITTLE CHANGE IN THE OVERALL PATTERN...ASIDE FROM THE SLOW APPROACH OF THE AREA OF LOW PRESSURE FROM FL...LOW CLOUDS ARE APT TO REDEVELOP AMIDST CONTINUED MOIST SOUTHERLY FLOW TONIGHT...WITH A CONTINUED CHANCE OF SHOWERS AND STORMS OVER THE FAR EASTERN AND SOUTHEASTERN FRINGES OF THE RAH COASTAL PLAIN. LOWS 68 TO 74.
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&& .SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
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AS OF 400 AM MONDAY... CENTRAL NC WILL REMAIN LARGELY SANDWICHED BETWEEN THE NEARLY STATIONARY FRONTAL ZONE OVER THE EASTERN CAROLINAS AND NORTHEAST DRIFTING AREA OF LOW PRESSURE ACROSS THE COASTAL CAROLINAS...AND A COLD FRONT FORECAST TO APPROACH FROM THE NORTHWEST AND STALL NEAR THE NC/VA STATE BORDER BY WED MORNING. THE RESULT WILL BE A CONTINUED CHANCE OF SHOWERS AND STORMS OVER THE COASTAL PLAIN...IN CLOSEST PROXIMITY TO THE STATIONARY FRONT. AND ELSEWHERE...THERE WILL BE A SLIGHT CHANCE OF A LATE AFTERNOON AND EVENING STORM FROM ACTIVITY THAT COULD EITHER DEVELOP IN-SITU INVOF A PIEDMONT SURFACE TROUGH AND/OR THAT WILL INITIATE UPSTREAM OVER THE MOUNTAINS AND INVOF THE AFOREMENTIONED FRONT...WHICH WOULD THEN PROPAGATE AWAY FROM THOSE FORCING MECHANISMS AND INTO THE NC PIEDMONT. FORECAST LOW LEVEL THICKNESS VALUES RISE ABOUT 5-10 METERS PER A CONSENSUS OF MODEL GUIDANCE...SUPPORTIVE OF LOWER TO MIDDLE 90S AREA-WIDE...WITH A FEW 97-98 DEGREE READINGS POSSIBLE FROM AFP TO FAY. LOWS GENERALLY 70 TO 75.
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&& .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 240 AM MONDAY... REALLY NO CHANGES TO THE UPPER LEVEL PATTERN DURING THE LONG TERM WHICH WILL FEATURE AN UPPER LEVEL RIDGE OVER THE SOUTHWESTERN CONUS AND A WEAK UPPER TROUGH OVER THE EAST COAST. SEVERAL SHORT WAVES WILL MAKE THEIR WAY THROUGH THE UPPER LEVEL FLOW DURING THIS PERIOD AND THERE IS QUITE A BIT OF UNCERTAINTY REMAINING IN THE FORECAST WITH REGARD TO TIMING OF THESE FEATURES. PRIOR SIMULATIONS HAD SHOWED THE FIRST IMPULSE MOVING THROUGH ON THURSDAY...BUT THIS FEATURE ALTHOUGH STILL THERE...HAS WEAKENED CONSIDERABLY AND MAY BE OF LITTLE CONSEQUENCE OTHER THAN A FEW SHOWERS BY THE TIME IT MOVES ACROSS THE AREA THURSDAY MORNING INTO EARLY AFTERNOON. IT APPEARS MODELS ARE HONING IN ON A SHORTWAVE ON EARLY FRIDAY TO BE THE MOST VIGOROUS OF THE PERIOD. WHILE THIS FEATURE REMAINS DISORGANIZED IN THE GFS SIMULATION...THE ECMWF MODEL IS WRAPPING IT UP INTO QUITE A STRONG LOW THAT PASSES ACROSS VIRGINIA BEFORE EXITING OFF OF THE DELMARVA COAST. DIURNAL TIMING LOOKS A LITTLE OFF WITH THE BEST SHEAR ARRIVING PRIOR TO THE BEST INSTABILITY...WHICH SHOULD HELP CUT BACK SEVERE CHANCES. THAT BEING SAID...TIMING HAS CHANGED SO MUCH WITH THE SUCCESSIVE RUNS OF THE MODELS THAT TO THINK THIS RUN IS ACCURATE WITHIN 6-12 HOURS WOULD BE NAIVE SO WE WILL HAVE TO WAIT AND SEE HOW THE TIMING LINES UP IN LATER RUNS. IF SUCCESSIVE RUNS COME IN A LITTLE LATER AND THE ECMWF IS RIGHT WITH THE INTENSITY...THEN SEVERE CHANCES COULD INCREASE QUITE A BIT FOR FRIDAY AFTERNOON EVENING. AT THIS POINT WILL JUST CARRY CHANCE OF THUNDER FRIDAY MORNING INTO THE AFTERNOON HOURS. FOR THE WEEKEND...BOTH DAYS SHOULD BE RELATIVELY DRY COMPARED TO FRIDAY...BUT SOME LINGERING WEAK ENERGY IN THE NORTHERN STREAM COULD CAUSE SOME SHOWERS...ESPECIALLY IN THE NW PIEDMONT AND VA BORDER COUNTIES. ON SATURDAY NIGHT INTO SUNDAY...THE ECMWF DEVELOPS THE ACTIVITY NOW IN THE NORTHEAST GULF OF MEXICO AS IT EMERGES OF OF THE NE FLORIDA COAST. THIS SURFACE LOW TRAVELS UP THE CAROLINA COAST AND COULD BE OFF OF THE OUTER BANKS BY SUNDAY NIGHT BUT AT THIS TIME APPEARS SHOWER ACTIVITY SHOULD BE TOO FAR EAST TO THREATEN ANY OF THE EASTERN COUNTIES. TEMPERATURES WILL BEGIN THIS PERIOD IN THE MID 90S BUT CONTINUE TO FALL INTO THE MID 80S BY THE END OF THE WEEKEND. LOWS WILL ALSO DROP OFF FROM THE LOW TO MID 70S TO THE MID TO UPPER 60S BY THE END OF THE PERIOD. && .AVIATION /06Z MONDAY THROUGH THURSDAY/... AS OF 220 AM MONDAY... MOIST SOUTHERLY FLOW ON THE NE PERIPHERY OF AN AREA OF LOW PRESSURE NEAR THE BIG BEND OF FL THIS MORNING WILL SUPPORT THE CONTINUED NORTHWARD DEVELOPMENT/EXPANSION OF AN AREA OF SCATTERED TO BROKEN MVFR RANGE CLOUDS INTO CENTRAL NC THIS MORNING...WITH THE RELATIVE HIGHEST PROBABILITY OF OCCURRENCE AND LONGEST DURATION AT FAY...WHERE FLEETING MVFR CEILINGS HAVE ALREADY BEEN REPORTED IN THE PAST COUPLE OF HOURS. THE LOW CLOUDS ARE EXPECTED TO LIFT AND SCATTER TO VFR BETWEEN 13-15Z...THOUGH PERIODS OF CUMULUS CEILINGS BETWEEN 3500-6000 FT ARE APT CONTINUE AT EASTERN TAF SITES THROUGHOUT THE DAY. THE INCREASED CLOUD COVER AT EASTERN SITES WILL ALSO SUPPORT A RELATIVE HIGHER PROBABILITY OF A SHOWER OR STORM FROM LATE MORNING ONWARD. CONTINUED MOIST SOUTHERLY LOW LEVEL AROUND THE AFOREMENTIONED LOW PRESSURE AREA OVER FL WILL RESULT IN A MEDIUM CHANCE...40-50 PERCENT...OF THE REDEVELOPMENT OF IFR-MVFR CEILINGS THROUGHOUT CENTRAL NC TONIGHT. ASIDE FROM AN ISOLATED TO WIDELY SCATTERED AFTERNOON AND EVENING STORM...GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH MID-WEEK. A FRONT WILL SETTLE INTO NC BY THE END OF THE WEEK...AT WHICH TIME THE PROBABILITY OF SHOWERS AND STORMS...AND SUB-VFR CONDITIONS...ARE EXPECTED TO INCREASE. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...26 NEAR TERM...26 SHORT TERM...26 LONG TERM...ELLIS AVIATION...26

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