Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 270210 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1010 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 /TONIGHT/...
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AS OF 1000 PM TUESDAY... OFFSHORE HIGH PRESSURE WILL CAUSE CONTINUED LIGHT SOUTHWESTERLY FLOW AT THE SURFACE...COUPLED WITH SLIGHT RIDGING AND NORTHWESTERLY FLOW ALOFT. A COLD FRONT SITUATED TO THE NORTH FROM SOUTHERN NEW JERSEY WESTWARD TO NORTHERN KENTUCKY WILL BE SLOWLY MOVING SOUTHWARD...BUT WILL REMAIN WELL NORTH OF CENTRAL NC THROUGH TONIGHT. A LINE OF PRE- FRONTAL CONVECTION AND ASSOCIATED OUTFLOW OVER WEST VIRGINIA IS BEING ADVECTED S/SE WITH THE MEAN FLOW...AND THIS ACTIVITY MAY MAKE ITS WAY INTO THE NORTHERN PIEDMONT LATE TONIGHT (BETWEEN 08-12Z). LASTLY...AN MCS UPSTREAM STRETCHING FROM SOUTHERN INDIANA INTO NORTHEAST ARKANSAS...AND ASSOCIATED MCV OVER SOUTH-CENTRAL INDIANA...IS ALSO MOVING TOWARD OUR AREA...BUT THESE FEATURES ARE NOT EXPECTED TO HAVE ANY IMPACT ON OUR FORECAST AREA UNTIL TOMORROW. LOW TEMPERATURES WILL BE IN THE LOW 60S.
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&& .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... 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. && .LONG TERM /THURSDAY THROUGH TUESDAY/... 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. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... AS OF 810 PM TUESDAY... WITH A FRONTAL ZONE DRAPED ACROSS THE OH VALLEY AND MID-ATLANTIC STATES...SOUTHERLY FLOW WILL CONTINUE TONIGHT WITH PREDOMINATELY VFR CONDITIONS. MULTIPLE AREAS OF STORMS IN THE VICINITY OF THE FRONT WILL MOVE INTO CENTRAL AND WESTERN VA THIS EVENING...WHICH COULD SPAWN AN OUTFLOW BOUNDARY THAT MOVES INTO NORTHERN NC AFTER MIDNIGHT. IT REMAINS VERY UNCERTAIN WHETHER OR NOT THIS WOULD TRIGGER ANY ADDITIONAL SHOWERS...BUT IF SO...THEY WOULD BE MOST LIKELY NORTH OF KRDU AND KRWI. IMPACTS AT THESE TAF SITES WOULD BE MINIMAL AND LIMITED TO A BRIEF PERIOD OF MVFR CEILINGS. THE FRONT...ALONG WITH ONE OR MORE OUTFLOW BOUNDARIES WILL MOVE NEAR THE NC/VA BORDER EARLY WEDNESDAY AND SHOULD BE THE FOCUS FOR SHOWERS AND STORMS BY WEDNESDAY AFTERNOON. WHILE CONFIDENCE IN THE TIMING OF ANY SHOWERS OF STORMS IS LOW...THEY WILL BRING THE CHANCE OF SUB- VFR CONDITIONS TO PRIMARILY KGSO/KINT/KRDU/KRWI. OUTLOOK... THE PRESENCE OF THE FRONTAL ZONE ACROSS THE REGION WILL SUPPORT PERIODS OF SHOWERS AND STORMS THROUGH WEDNESDAY AND POSSIBLE INTO FRIDAY. 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...DND/26 SHORT TERM...CBL LONG TERM...KRD AVIATION...22

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