Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 030640 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 240 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/... AS OF 1045 PM SUNDAY... A FEW ISOLATED SHOWERS HAVE DEVELOPED ALONG THE SEA BREEZE THIS EVENING. WITH LOW-LEVEL LAPSE RATES AROUND 6.5 C/KM...THERE IS JUST ENOUGH CAPE THAT THE SEA BREEZE IS A SUFFICIENT FORCING MECHANISM FOR CONVECTION. ALTHOUGH A LIGHTNING STRIKE IS POSSIBLE...THESE SHOWERS WILL GENERALLY BE FAIRLY BENIGN...WITH JUST SOME BRIEF LOCALLY HEAVY RAIN. OTHERWISE...MOST LOCATIONS TONIGHT SHOULD REMAIN DRY AND CLEAR WITH LOWS IN THE MID 60S NORTH TO LOW 70S SOUTH. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 330 PM SUNDAY... MONDAY AND MONDAY NIGHT... A WELL-DEFINED LOW LEVEL CIRCULATION OVER THE FAR NE GULF WILL DRIFTING NEWD MONDAY AND MONDAY NIGHT IN RESPONSE TO A S/W CROSSING THE LOWER OH AND TN VALLEYS. THIS SFC LOW WILL INCREASES CONVERGENCE ALONG A STALLED SFC BOUNDARY IN VICINITY OF THE NC COAST. THIS SFC FEATURE EXPECTED TO DRIFT INTO THE COASTAL PLAIN BUT NOT LIKELY AS FAR WEST AS I-95. REGIONAL WRF MODELS OFFERING VARYING SOLUTIONS WITH SOME DEPICTING VERY LITTLE OVER OUR CWA...WHILE SOME SUGGEST SCATTERED CONVECTION AS FAR WEST AS THE EASTERN PIEDMONT ON MONDAY AFTERNOON. THE TRUTH IS LIKELY SOMEWHERE IN BETWEEN. WILL INCREASE RAIN CHANCE TO SOLIDLY CHANCE/LOW END LIKELY OVER SECTIONS OF SAMPSON COUNTY...WITH POPS QUICKLY DWINDLING TO THE WEST-NW OVER THE REMAINDER OF THE SOUTHERN COASTAL PLAIN AND SANDHILLS. APPEARS THAT ANY CONVECTION THAT DEVELOPS OVER THE PIEDMONT WILL BE ISOLATED (IF IT FORMS AT ALL) AS ATMOSPHERE PROJECTED TO REMAIN RELATIVELY DRY (FOR EARLY AUGUST) AND CONDITIONALLY STABLE. FAIRLY CONFIDENT THAT A MIXTURE OF CLOUDS/SUN WILL PREVAIL OVER THE PIEDMONT MONDAY...RESULTING IN AFTERNOON TEMPS NEAR 90-LOWER 90S. OVER THE SE THIRD...CONFIDENCE NOT AS HIGH AS MAY SEE A DECENT VEIL OF CLOUDS...LIMITING INSOLATION. AND IF CONVECTIVE COVERAGE IS MORE THAN ANTICIPATED...AFTERNOON TEMPS IN THE MID 80S MAY BE ALL SHE WROTE. USED ADJUSTED MAV MOS GUIDANCE FOR HIGH TEMPS MONDAY WITH GENEROUS SMOOTHING/EDITING. MAY SEE A FEW SHOWERS/STORMS PERSIST WELL INTO THE EARLY EVENING HOURS MONDAY...MAINLY OVER THE CENTRAL-SOUTHERN COASTAL PLAIN. ELSEWHERE EXPECT VARYING DEGREES OF CLOUDINESS...MORE SO SE VERSUS NW. MIN TEMPS NEAR 70-LOWER 70S. TUESDAY AND TUESDAY NIGHT... LOW LEVEL BECOMES MORE SLY AND USHER A MOIST AIR MASS INTO CENTRAL NC. ALOFT...FLOW MAINLY WLY BUT STILL RATHER STABLE. STRONG HEATING OF THE MOIST AIR IN THE LOWER LEVELS SHOULD SUPPORT THE DEVELOPMENT OF ISOLATED CONVECTION..MAINLY IN THE MID AFTERNOON THROUGH THE EARLY EVENING HOURS. A LEE-SIDE TROUGH WILL INDUCE A SW FLOW OVER OUR REGION WHILE AIR MASS REMAINS WARM/DRY ALOFT. THICKNESSES TOP OUT AROUND 1440M OVER THE PIEDMONT...SUPPORTIVE OF AFTERNOON TEMPS IN THE MID 90S. MOIST LOW LEVEL AIR MASS WILL LIKELY CAUSE AREAS OF STRATUS TO DEVELOP LATE TUESDAY NIGHT. MIN TEMPS NEAR 70-LOWER 70S. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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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.
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&& .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...RAH SHORT TERM...WSS LONG TERM...ELLIS AVIATION...26

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