Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 271350 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 950 AM EDT FRI MAR 27 2015 .SYNOPSIS...
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A COLD FRONT WILL MOVE OFF THIS COAST THIS MORNING. TRAILING THE FRONT...A POTENT UPPER LEVEL TROUGH WILL MOVE TROUGH THE REGION THIS EVENING AND OVERNIGHT. DRY HIGH PRESSURE WILL BUILD INTO THE REGION OVER THE WEEKEND.
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&& .NEAR TERM /TODAY AND TONIGHT/...
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AS OF 950 AM FRIDAY... TODAY: COLD FRONT IS IN THE PROCESS OF PUSHING SOUTH OF THE AREA...AND WILL MOVE OFF THE SE NC COAST AOA MIDDAY...SLOWING DOWN IN THE PROCESS OWING TO THE APPROACH OF THE AMPLIFYING UPPER LEVEL TROUGH DIGGING SOUTHWARD INTO THE SOUTHERN APPALACHIANS. GIVEN PLENTIFUL MOISTURE...MARGINAL ELEVATED INSTABILITY...AND INCREASING DEEP-LAYER FORCING IN ADVANCE OF THE AMPLIFYING TROUGH...LARGE BAND OF ANAFRONTAL SHOWERS WILL PROGRESS SLOWLY EASTWARD ACROSS THE FORECAST AREA FOR MUCH OF THE DAY...ESP IN THE COASTAL PLAIN WHERE PRECIP IS EXPECTED TO LINGER INTO THE 21-00Z TIME FRAME. TEMPERATURES BEHIND THE FRONT DROP A GOOD 15 DEGREES...AND GIVEN OVERCAST SKIES... CONTINUED COLD ADVECTION...AND PRECIPITATION/EVAP COOLING/...MOST AREAS HAVE ALREADY SEEN THEIR HIGH FOR TODAY...WITH RATHER UNIFORM TEMPERATURES THIS AFTERNOON IN THE MID 40S. THE EXCEPTION COULD BE ACROSS THE WESTERN PIEDMONT WHERE CLOUD COVER MAY THIN ENOUGH FOR TEMPS TO RISE SEVERAL DEGREES TO NEAR 50 DEGREES. TONIGHT: THE AMPLIFYING UPPER LEVEL TROUGH WILL PROGRESS ACROSS THE CAROLINAS LATE THIS EVENING INTO TONIGHT. STRONG DPVA /LAYER LIFTING/ AND COLD ADVECTION ALOFT (H7 TEMPS FALLING 10C BETWEEN 21Z- 03Z IN THE TRIAD) WILL RESULT IN MARGINAL NOCTURNAL DESTABILIZATION AND A POTENTIAL FOR ISOLD TO SCT LOW-TOPPED SHOWERS FROM WEST-EAST IN THE 02-08Z TIME FRAME. THE LATEST GUIDANCE SUGGESTS THAT LOW-LEVEL THERMAL PROFILES WILL BE EXCLUSIVELY SUPPORTIVE OF RAIN DURING THE TIME-FRAME IN WHICH SHOWER ACTIVITY WILL BE POSSIBLE. LOWS WILL BE DRIVEN BY A COMBINATION OF COLD ADVECTION AND RADIATIONAL COOLING BETWEEN 06-12Z AS SYNOPTIC SUBSIDENCE /CLEARING/ COMMENCES IN THE WAKE OF THE UPPER LEVEL TROUGH AND THE MSLP GRADIENT TIGHTENS. EXPECT LOWS RANGING FROM 33-36F IN THE NW PIEDMONT TO NEAR 40F IN THE SE COASTAL PLAIN.
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&& .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 300 AM FRIDAY... SATURDAY: STRONG SYNOPTIC SUBSIDENCE AND LOW-LEVEL COLD ADVECTION IN THE WAKE OF THE UPPER LEVEL TROUGH WILL ENSURE MOSTLY CLEAR SKIES AND WELL BELOW NORMAL HIGHS ON SAT...RANGING FROM THE LOWER 40S IN THE N/NW PIEDMONT TO NEAR 50F IN THE SE COASTAL PLAIN. -VINCENT COLD DRY AIRMASS IN PLACE WILL HAVE IDEAL RADIATIONAL CONDITIONS FOR A TEMPERATURE CRASH SATURDAY NIGHT...AND THE PROGRESSIVELY COLDER MODEL TREND NOW SPORTS LOW LEVEL THICKNESSES BELOW 1280 METERS. LOCAL STUDIES SUGGEST THAT WE NEED ANOTHER MINOR TWEAK DOWNWARD INTO THE LOWER 20S ACROSS THE NORTH TO MID 20S ACROSS THE SOUTH. THE SURFACE HIGH SHIFTS SOUTHEAST AND OFFSHORE WITH THE ENSUING RETURN FLOW INITIATING A MODEST WARMUP ON SUNDAY INTO MOSTLY THE MID 50S. ANOTHER FAST MOVING SYSTEM WILL BE DIVING INTO THE AREA LATER SUNDAY NIGHT...WITH ASSOCIATED CLOUDINESS ARRIVING LATE TO AID LIGHT SOUTHERLY WARM AIR ADVECTION TO LIMIT THE DIURNAL TEMP CRASH TO THE MID AND UPPER 30S. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 335 AM FRIDAY... A FAST MOVING UPPER TROF AND ASSOCIATED FRONT WILL MOVE SOUTHEAST ACROSS THE AREA EARLY ON MONDAY. THE PARENT SYSTEM IS NORTH OF THE GREAT LAKES SO WE WILL HAVE WESTERLY FLOW ACROSS THE SOUTHERN TIER OF THE EASTERN CONUS...HENCE NO MOISTURE ADVECTION. WILL THUS HAVE SMALL CHANCE POPS WEST WHERE THE WEAKENING SYSTEMS CHANCE OF SQUEEZING OUT SOME LIGHT SHOWERS WILL BE AIDED BY TOPOGRAPHY... TAPERED TO ONLY A SLIGHT CHANCE IN THE EAST. ONLY A FEW HUNDREDTHS OF AN INCH ARE EXPECTED. HIGHS ON MONDAY WILL ACTUALLY BE WARMING DUE TO THE WESTERLY DOWNSLOPE FLOW...WITH HIGHS RANGING FROM 60 TO 65. GRADUAL MODIFICATION IN TEMPERATURES WILL CONTINUE INTO MID WEEK AS WE REMAIN BETWEEN THE NORTHERN AND SOUTHERN JET STREAMS WITH GENERALLY WESTERLY FLOW AND MORE ABUNDANT INSOLATION. HIGHS ON TUESDAY WILL BE MOSTLY IN THE UPPER 60S...WITH SOME LOWER 70S SHOWING UP ACROSS THE SOUTHERN HALF OF THE AREA ON WEDNESDAY. A SOUTHERN STREAM SYSTEM WILL BE EVOLVING OVER THE LOWER MIDWEST BY MID WEEK...AND THE TIMING OF ITS PROGRESS EAST ACROSS THE GULF STATES AND THE EVENTUAL ARRIVAL OF RAIN IS SOMEWHAT LOWER CONFIDENCE...WITH POPS INTRODUCED EARLY ON THURSDAY IN THE WEST...GRADUALLY INCREASING INTO THE OVERNIGHT. THIS SYSTEM COULD LINGER INTO FRIDAY AS WELL...AND WILL INTRODUCE DAY 7 WITH SLIGHT CHANCE POPS. HIGHS THURSDAY AND FRIDAY WILL RANGE FROM 70 TO 75. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... AS OF 735 AM FRIDAY... 24-HR TAF PERIOD: MVFR/IFR CEILINGS AND WIDESPREAD SHOWERS WILL AFFECT ALL TERMINALS BY 12-14Z THIS MORNING...IN THE WAKE OF A COLD FRONTAL PASSAGE. WINDS WILL BECOME N/NE AT 10-15 KT WITH GUSTS UP TO 25 KT BETWEEN 12-18Z AS THE MSLP GRADIENT TIGHTENS BEHIND THE FRONT. MVFR/IFR CEILINGS AND SHOWERS WILL PERSIST FOR MUCH OF THE DAY... PARTICULARLY AT EASTERN TERMINALS (RDU/FAY/RWI) WHERE IMPROVEMENT MAY NOT OCCUR UNTIL 21-00Z. AT WESTERN TERMINALS (INT/GSO)...SOME IMPROVEMENT TO HIGH-END MVFR OR VFR WILL BE POSSIBLE BY 18-21Z. HOWEVER...CONDITIONS WILL DETERIORATE TO MVFR/IFR ALONG WITH A POTENTIAL FOR ISOLD/SCT SHOWERS LATE THIS EVENING INTO TONIGHT (02- 08Z) AS A POWERFUL UPPER LEVEL TROUGH TRACKS ACROSS THE REGION. CONDITIONS WILL RETURN TO VFR AS SKIES RAPIDLY CLEAR FROM WEST-EAST ON THE BACK SIDE OF THE TROUGH BETWEEN 06-12Z SAT MORNING. LOOKING AHEAD: VFR CONDITIONS WILL RULE OVER THE WEEKEND AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE WEST/NW. THE NEXT POTENTIAL FOR ADVERSE CONDITIONS WILL BE ASSOC/W AN UPPER LEVEL DISTURBANCE MONDAY AFTERNOON...WITH VFR CONDITIONS EXPECTED THEREAFTER. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL/VINCENT NEAR TERM...CBL/VINCENT SHORT TERM...VINCENT/MLM LONG TERM...MLM AVIATION...VINCENT

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