Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 261935 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 335 PM EDT TUE APR 26 2016 .SYNOPSIS... A WEAKENING FRONTAL ZONE WILL APPROACH THE AREA FROM THE NORTH TONIGHT...THEN STALL OVER PORTIONS OF THE CAROLINAS ON WEDNESDAY AND THURSDAY. && .NEAR TERM /TODAY AND TONIGHT/...
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AS OF 315 PM TUESDAY... OVERVIEW: SHEARING SHORTWAVE ENERGY MOVING EASTWARD THROUGH THE NORTHERN MID-ATLANTIC STATES WILL PUSH A STATIONARY FRONTAL ZONE SOUTHWARD INTO THE SOUTHERN MID-ATLANTIC STATES LATE TONIGHT...PROGGED TO STALL NEAR THE VIRGINIA STATE LINE ON WEDNESDAY. IN THE MEANTIME...THE SE US...INCLUDING CENTRAL NC WILL REMAIN UNDERNEATH LOW-AMPLITUDE RIDGING WITH LATEST SFC ANALYSIS INDICATING THE DEVELOPMENT OF A LEE SIDE SFC TROUGH OVER THE NC/VA FTHLS. FORCING FOR CONVECTION THIS AFTERNOON WILL BE WEAK WITH AFOREMENTIONED LOW-AMPLITUDE RIDGE DEFLECTING ANY SUBSTANTIAL DISTURBANCES OFF TO THE NORTH. INSTEAD...WEAK SFC CONVERGENCE INVOF THE LEE SIDE SURFACE TROUGH...ALONG WITH DIFFERENTIAL HEATING OVER THE HIGHER TERRAIN WILL SERVE AS THE PRIMARY FOCUS FOR ISOLATED SHOWERS AND STORMS...WITH BEST CHANCES FOR THESE STORMS TO DRIFT INTO THE FAR NW PIEDMONT COUNTIES. WHILE INSTABILITY WILL BE BETTER THAN RECENT DAYS...WEAK TO MARGINALLY MODERATE INSTABILITY WITH MLCAPE VALUES ON THE ORDER OF 750-1000J/KG AND BULK SHEAR VALUES ~25KTS MAY SUPPORT AN ISOLATED STRONG TO SEVERE STORM. TONIGHT: CONVECTION AHEAD AND ALONG THE FRONT WILL ATTEMPT TO HOLD TOGETHER AS IT PUSHES SOUTH TOWARDS THE AREA OVERNIGHT... PARTICULARLY IF ANY REMNANTS OF THE ONGOING MCS OVER MISSOURI CAN HOLD TOGETHER AND TRACK ALONG THE FRONT. MODELS INDICATE SIGNIFICANT WEAKENING OF THIS FEATURE AS IT EJECTS SOUTHEASTWARD TOWARDS THE AREA WITH LINGERING ELEVATED INSTABILITY SUFFICIENT ENOUGH TO SUPPORT SMALL CHANCE POPS AND THUNDER OVERNIGHT NORTH OF HIGHWAY 64. LOWS IN THE LOWER TO MID 60S.
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&& .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
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AS OF 330 PM TUESDAY... THERE IS STILL CONSIDERABLE DIFFERENCES BETWEEN THE GFS AND ECMWF WRT TO CONVECTION CHANCES/POPS WEDNESDAY AND WEDNESDAY NIGHT. THE ECMWF REMAINS SIGNIFICANTLY DRIER AS IT KEEPS THE FRONT JUST SLIGHTLY NORTH OVER SOUTHERN VIRGINIA WHILE THE GFS SAGS THE FRONT DOWN INTO NORTHERN PIEDMONT AND COASTAL PLAIN OF NC. SENSIBLE WEATHER IMPACTS WILL BE STRONGLY CONTINGENT ON THE EXACT LOCATION OF THE FRONT...WITH DIFFICULT TO RESOLVE MESOSCALE FEATURES SUCH AS CONVECTIVE OUTFLOW AND/OR DIFFERENTIAL HEATING LIKELY TO PLAY A KEY ROLE IN THE EVENTUAL LOCATION. STATIONARY FRONT NEAR THE NC/VA LINE SHOULD SERVE AS A SUFFICIENT FOCUS FOR AT LEAST ISOLATED TO SCATTERED CONVECTIVE DEVELOPMENT DURING PEAK HEATING AND RESULTANT MODERATE DESTABILIZATION(1500- 1700J/KG OF MUCAPE)...WITH HIGHS POPS/COVERAGE EXPECTED ACROSS THE NORTH INVOF THE FRONT. CONVECTION COULD HAVE A DIURNAL SIGNAL...BUT GIVEN THE POTENTIAL FOR SOME WEAK SHORTWAVE DISTURBANCES TO EJECT EASTWARD OUT AHEAD OF THE NEGATIVELY-TILTED SHORTWAVE TROUGH LIFTING SLOWLY NORTHWARD ACROSS THE CENTRAL PLAINS...CONVECTION ALONG THE FRONT COULD REMAIN FAIRLY ACTIVE THROUGH THE EVENING AND WELL INTO THE OVERNIGHT HOURS. DEEP LAYER SHEAR 20-30KTS...STRONGEST INVOF THE FRONT...WILL BE SUFFICIENT TO SUPPORT ISOLATED HAIL AND/OR DAMAGING WIND GUSTS. AGAIN...TEMPERATURES WILL DEPEND ON THE EXACT LOCATION OF THE FRONT. HIGHS RANGING FROM UPPER 70S TO LOWER 80S ACROSS THE NORTH TO MID/UPPER 80S SOUTH. LOWS WEDNESDAY NIGHT RANGING FROM UPPER 50S/LOWER 60S NORTH TO MID 60S SOUTH.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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AS OF 315 PM TUESDAY... ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THURSDAY AND THURSDAY NIGHT AS ANOTHER WAVE TRACKS FROM THE OHIO VALLEY TOWARDS THE MID ATLANTIC. THIS SYSTEM WILL PULL A COLD FRONT THROUGH THE REGION LATE THURSDAY INTO EARLY FRIDAY. CONVECTION COULD BE ONGOING OVER PARTS OF CENTRAL NC TO BEGIN THE DAY ON THURSDAY...BUT SHOULD BECOME MORE WIDESPREAD AND ORGANIZED DURING THE AFTERNOON AND EVENING HOURS. THE AMOUNT OF INSTABILITY WILL DEPEND ON HOW MUCH HEATING IS ABLE TO OCCUR GIVEN THE INCREASING CLOUD COVERAGE/PRECIP. FOR NOW IT LOOKS LIKE UPPER 70S TO LOW/MID 80S WILL BE LIKELY AND GIVEN DEWPOINTS IN THE 60S...AMPLE INSTABILITY SHOULD DEVELOP. HOWEVER...IF LESS HEATING IS REALIZED...OUR INSTABILITY MAY BE LACKING. REGARDLESS...BULK SHEAR VALUES ARE PROGGED TO BE IN THE 30- 35 KNOT RANGE AND THUS...THE SPC HAS PLACED THE ENTIRE REGION IN A MARGINAL RISK AND THE SEVERE THREAT WILL CONTINUE TO BE MONITORED. CONDITIONS SHOULD BEGIN TO CLEAR OUT BEHIND THE FRONT THROUGHOUT THE DAY ON FRIDAY...ALTHOUGH A TRAILING UPPER LEVEL DISTURBANCE COULD TRIGGER SOME STORMS DURING THE AFTERNOON HOURS...MAINLY ACROSS THE NORTHEAST. SATURDAY SHOULD BE MOSTLY DRY AS HIGH PRESSURE AND SHORTWAVE RIDGING BRIEFLY BUILD OVER THE AREA. TEMPS WILL ALSO COOL DOWN...WITH HIGHS GENERALLY IN THE 70S. OUR NEXT SYSTEM IS THEN PROGGED TO APPROACH THE AREA SUNDAY INTO MONDAY. ALTHOUGH THERE ARE PLENTY OF DIFFERENCES WITH THE DETAILS...ALL MODELS ARE HINGING ON AN ACTIVE PERIOD DURING THE SECOND HALF OF THE WEEKEND AND INTO EARLY NEXT WEEK. THERE WILL LIKELY BE SEVERAL ROUNDS OF PRECIP AND THEN RELATIVELY DRIER PERIODS...BUT TRYING TO TIME THOSE OUT THIS FAR OUT IN NEARLY IMPOSSIBLE. THEREFORE WILL JUST SHOW A TREND OF INCREASING CLOUDS AND PRECIP STARTING SUNDAY AND CONTINUING INTO NEXT WEEK.
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&& .AVIATION /18Z TUESDAY THROUGH SUNDAY/... AS OF 130 PM TUESDAY... 24-HOUR TAF PERIOD: EXPECT PREDOMINATELY VFR CONDITIONS TO PREVAIL THROUGH THE TAF PERIOD IN MOST LOCATIONS. THE EXCEPTION WILL BE AT KINT AND KGSO WHERE AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE LATE THIS AFTERNOON AND EVENING. OTHERWISE...IT SHOULD REMAIN DRY WITH BREEZY SWLY WINDS DIMINISHING THIS EVENING. LOOKING AHEAD: UPPER DISTURBANCES TRACKING ATOP A FRONTAL ZONE STALLED OVER THE REGION WILL SUPPORT SCATTERED SHOWERS AND STORMS THROUGH MID TO LATE WEEK. AS A RESULT...SUB-VFR CONDITIONS ASSOC/W CONVECTION WILL BE POSSIBLE AT ALL TERMINALS...ESPECIALLY ON THURSDAY AS IT LOOKS TO BE THE MOST ACTIVE DAY. PRE-DAWN FOG/STRATUS WILL BE POSSIBLE EACH MORNING...ESPECIALLY IN AREAS AFFECTED BY AFT/EVE CONVECTION. DRIER CONDITIONS BRIEFLY RETURN ON SATURDAY WITH THE NEXT SYSTEM BRINGING INCREASING CHANCES FOR SHOWERS AND RAIN LATE SUNDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...CBL SHORT TERM...CBL LONG TERM...KRD AVIATION...CBL

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