Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 270541 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 141 AM EDT WED MAY 27 2015 .SYNOPSIS...THE WESTERN EXTENT OF UPPER LEVEL RIDGE OVER THE WESTERN ATLANTIC...AND A SEASONABLY MOIST AIR MASS...WILL PREVAIL OVER THE REGION FOR THE WORK WEEK. && .NEAR TERM /OVERNIGHT/... AS OF 920 PM TUESDAY... AN AREA OF CONVECTION LIFTING NE ACROSS UPSTATE SC AND SW NC BEING MAINTAINED BY A MID LEVEL TROUGH AND ATTENDANT SPEED CONVERGENCE ALONG WITH UPPER DIVERGENCE...CENTERED MAINLY OVER THE SOUTHERN APPALACHIANS. THE 00Z GSO SOUNDING DEPICTS A FAIRLY SUBSTANTIAL CAP BETWEEN 750-700MB...A BIT STRONGER THAN PREDICTED BY THE NEAR TERM MODELS. EXPECT THIS AREA OF CONVECTION TO GRADUALLY WEAKEN AS IT ENCOUNTERS THE SLIGHTLY MORE STABLE AIR MASS OVER THE WESTERN PIEDMONT...BUT COULD STILL SEE A FEW SHOWERS LATE THIS EVENING INTO THE OVERNIGHT IN VICINITY OF THE TRIAD. OTHERWISE VARIABLY CLOUDY SKIES AND A LIGHT BUT PERSISTENT SLY SFC WIND WILL RESULT IN A MILD (THOUGH SLIGHTLY HUMID) NIGHT. MIN TEMPS MAINLY IN THE UPPER 60S. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 305 PM TUESDAY... INSTABILITY OVERALL INCREASES ACROSS CENTRAL NORTH CAROLINA WEDNESDAY...WITH SURFACE-BASED CAPE RISING TO JUST OVER 1000J/KG WHILE MLCAPE THROUGH THE LOWEST 3KM IS GENERALLY 500J/KG OR SO. LIFTED INDICES ARE FORECAST TO BE SLIGHTLY LOWER COMPARED TO TODAY... TO NEAR -5C WEDNESDAY AFTERNOON VERSUS ABOUT -3C. ALOFT...THERE IS FORECAST WEAK AND BROAD DIFFLUENCE AND WEAK CONVERGENCE AT 850MB...ALTHOUGH CERTAINLY THE NAM AND TO A LESSER EXTENT THE GFS FORECAST MODEST LIFT OVER CENTRAL NORTH CAROLINA FOR WEDNESDAY AFTERNOON. WINDS ALOFT ARE WEAK...AND ANY PIEDMONT TROUGH SHOULD BE SOMEWHAT WEAK AS WELL...LEADING TO A DAY WHERE SCATTERED MOSTLY DISORGANIZED SHOWERS AND THUNDERSTORMS SHOULD OCCUR AS THE DAY PROGRESSES. ONCE AGAIN...0-3KM SHEAR IS LOW AND 850MB AND 925MB WINDS ARE RELATIVELY LIGHT BY AFTERNOON...10 TO 20KT. HIGHS IN THE 80S. OVERNIGHT...BUFR SOUNDINGS FROM BOTH THE NAM AND GFS SHOW INCREASING STABILITY AS SURFACE HIGH PRESSURE IS FORECAST TO BUILD SOMEWHAT BACK WEST. FOR THIS FORECAST WILL DIMINISH CHANCES EAST TO WEST AND RETAIN A SLIGHT CHANCE OF SHOWERS IN THE OVERNIGHT HOURS ONLY TOWARD THE YADKIN RIVER ESPECIALLY FOR FORECAST CONSISTENCY...BUT IF THE NAM BUFR SOUNDINGS VERIFY IN PARTICULAR CENTRAL NORTH CAROLINA SHOULD HAVE BELOW SLIGHT CHANCE POPS AFTER 06Z. LOWS IN THE MID TO UPPER 60S. && .LONG TERM /THURSDAY THROUGH TUESDAY/... AS OF 210 PM TUESDAY... THE REMNANT MOISTURE AND SHEAR AXIS FROM THE SYSTEM CURRENTLY OVER THE MISS RIVER VALLEY WILL MOVE EAST AND BECOME CENTERED OVER CENTRAL NC BY THURSDAY. WHILE THE BEST MID/UPR ENERGY WILL HAVE LIFTED WELL TO OUR NORTH...THERE SHOULD BE ENOUGH MOISTURE AND FORCING FOR AT LEAST SCATTERED AFTERNOON/EVENING SHOWERS/TSTMS. INSTABILITY AND SHEAR VALUES SUGGEST SUB-SEVERE ACTIVITY. THE UPPER RIDGE OFF THE EAST COAST WILL THEN REBUILD OVER THE SOUTHEAST COASTAL REGION FRIDAY THROUGH THE WEEKEND...AND SHOULD HELP LIMIT THE COVERAGE OF SHOWER/TSTM ACTIVITY OVER OUR AREA FRIDAY AND SATURDAY. A COLD FRONT CROSSING THE MIDWEST ON FRIDAY IS PROGGED BY THE LATEST GFS TO DROP SOUTH ACROSS OUR AREA BY SUNDAY AND DISSIPATE OVER US BY MONDAY. DESPITE THE LIFT PROVIDED BY THIS FRONT...MODELS SUGGEST THE AFOREMENTIONED RIDGE OVER THE SOUTHEAST WILL KEEP THE BULK OF THE MOISTURE JUST TO OUR NORTH. NEVERTHELESS...THERE`S ENOUGH FORCING AND MOISTURE TO WARRANT A DECENT CHANCE POP ACROSS OUR AREA LATE IN THE WEEKEND INTO EARLY NEXT WEEK. AS FOR TEMPS...PERSISTENCE IS THE BEST FORECAST AT THIS POINT WITH LITTLE CHANGE IN THE AIRMASS. HIGHS IN THE MID TO UPPER 80S AND LOWS IN THE MID 60S EACH DAY DURING THE PERIOD. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... AS OF 140 AM WEDNESDAY... CONVECTION ACROSS THE WESTERN PIEDMONT CONTINUES TO WEAKEN...AND SHOULD DIMINISH OVER THE NEXT HOUR OR TWO WITH NO FURTHER AVIATION IMPACTS AT KGSO...KINT OR KRDU. SOUTH-SOUTHEASTERLY RETURN FLOW AROUND BERMUDA HIGH PRESSURE OVER THE WESTERN ATLANTIC WILL MAINTAIN A MOIST LOW-LEVEL FEED OVER THE AREA...CREATING FAVORABLE CONDITIONS FOR THE DEVELOPMENT OF SUB-VFR STRATUS AT ALL TAF SITES BETWEEN 06 TO 14Z. BY 15 TO 16Z...ANY SUB-VFR CEILINGS SHOULD LIFT TO VFR. MAINLY DIURNAL ISOLATED TO SCATTERED SHOWERS AND STORMS ARE EXPECTED THIS AFTERNOON. BUT THIS PROBABILITY APPEARS TOO LOW TO MENTION IN THE TERMINAL FORECAST AT THIS TIME. BEYOND THE 00Z VALID TAF PERIOD...THE THREAT FOR RESTRICTIONS IN EARLY MORNING FOG/STRATUS WILL CONTINUE THE WEEKEND AS BERMUDA HIGH PRESSURE HOLDS OVER THE AREA. ISOLATED TO SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS ARE EXPECTED AGAIN ON THURSDAY. RAIN CHANCES WILL BEGIN TO INTO THE WEEKEND AS UPPER LEVEL RIDGE RETROGRADES WEST OVER THE AREA. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...WSS SHORT TERM...DJF LONG TERM...RAH AVIATION...CBL

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