Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 250337 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1030 PM EST MON NOV 24 2014 .SYNOPSIS...A COLD FRONT WILL TRACK SLOWLY EAST ACROSS THE REGION TONIGHT BEFORE STALLING NEAR THE SOUTHEAST COAST ON TUESDAY. A LOW PRESSURE SYSTEM WILL DEVELOP ON THE FRONT TUESDAY NIGHT... THEN TRACK NORTHEAST ALONG THE CAROLINA AND MID ATLANTIC COAST ON WEDNESDAY AS AN UPPER LEVEL DISTURBANCE APPROACHES FROM THE WEST. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM MONDAY... THE ACTIVE SUBTROPICAL JET COMBINED WITH THE NEARLY STATIONARY BOUNDARY LOCATED OVER THE PIEDMONT HAVE NECESSITATED BOOSTING RAIN CHANCES OVERNIGHT. THE WV SATELLITE DATA INDICATES ANOTHER WAVE APPROACHING NC FROM THE SSW WHICH HAS BACKED THE MID LEVEL FLOW AND MOISTURE BACK TO THE APPALACHIANS. IF THE LATEST GFS/NAM VERIFY... RAIN WILL HAVE TO BE ADDED TO THE FORECAST FOR TUESDAY AS THE MODELS PLAY CATCH UP WITH THE EVOLVING PATTERN. LOWS TONIGHT MAINLY IN THE 50S TO NEAR 60 SE. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... AS OF 315 PM MONDAY... THE FRONT IS EXPECTED TO STALL NEAR COASTAL NC THROUGH TUE... AS THE STEERING FLOW BECOMES PARALLEL TO THE FRONTAL ZONE AND CEASES ITS EASTWARD PUSH. THE BEST LOW LEVEL MOISTURE TRANSPORT SHIFTS JUST OFF THE COAST TUE MORNING... WHILE THE ELEVATED PW VALUES ACCORDINGLY GET BUMPED EASTWARD AS WELL. MUCH OF THE AREA SHOULD HAVE A QUIET AND DRY DAY WITH JUST SOME MID CLOUDS STREAKING NORTHEASTWARD OVER THE AREA ESPECIALLY OVER THE EASTERN HALF. THE TRADITIONAL MODELS AS WELL AS THE HI-RES WRF NMM/ARW AND THE SREF PROBABILITIES SUGGEST THAT OUR FAR SE CWA WILL STILL SEE SOME PATCHY LIGHT RAIN THROUGH THE DAY... LIKELY FALLING FROM AN ELEVATED CLOUD BASE WHICH WILL CUT DOWN ON QPF AS ANY RAIN SHOULD FALL THROUGH A SOMEWHAT DRY LAYER FROM 800-925 MB. WILL KEEP A LOW CHANCE OF RAIN OVER THE SOUTHEAST THROUGH TUE... WITH SAMPSON AND SE WAYNE COUNTIES SEEING THE BEST CHANCE OF MEASURABLE RAIN. EXPECT HIGHS OF AROUND 60 TO 66... WITH THE WEST HALF SEEING MUCH MORE SUN THAN THE EASTERN HALF. SURFACE LOW PRESSURE WILL FORM ALONG THE FRONT OVER THE NE GULF AND NRN FL LATE TUE... THEN TRACK TO THE NNE TO A POSITION OFF THE SRN NC COAST BY 12Z WED AS CENTRAL PRESSURES DROP 5 MB. STRENGTHENING UPPER DIVERGENCE IN THE RIGHT ENTRANCE REGION OF AN INTENSIFYING UPPER JET CORE (TO AROUND 200 KTS) FROM CENTRAL NC TO THE CANADIAN MARITIMES WILL CONTRIBUTE TO INCREASE LIFT FURTHER INLAND... AND WE`LL BEGIN TO SEE DECENT HEIGHT FALLS LATE. THIS ALONG WITH RE-MOISTENING OF THE COLUMN WILL SUPPORT INCREASING POPS TUE EVENING/NIGHT... UP TO CATEGORICAL EAST WITH GOOD CHANCE TO LIKELY WEST OVERNIGHT... ALTHOUGH THE MID LEVEL DPVA WILL BE RATHER MEAGER. THE COOLER AIR ADVECTING IN ALOFT WITH THE APPROACHING TROUGH AXIS BRINGS ABOUT A CONCERN FOR POSSIBLE NON-LIQUID PRECIP LATE TONIGHT. EXAMINING FORECAST SOUNDINGS HOWEVER... IT APPEARS THAT THE CLOUD BASES WILL BE RATHER HIGH INITIALLY WITH SURFACE TEMPS (AND WET BULBS) WELL ABOVE FREEZING... AND THAT BY THE TIME THE LOW LEVELS MOISTEN SUFFICIENTLY... THE LOWEST THOUSAND FEET IN THE TRIAD SHOULD REMAIN ABOVE FREEZING. AND BY THE TIME THE MARKED COOLING ARRIVES IN THE LOW LEVELS... WE WILL HAVE ALREADY DRIED OUT ALOFT. SO WHILE WE MAY SEE A FEW WET FLAKES IN THE NW PIEDMONT LATE TUE NIGHT... IT WILL BE OF ZERO CONSEQUENCE. EXPECT LOWS FROM 36 NW TO 44 SE. -GIH && .LONG TERM /WEDNESDAY THROUGH MONDAY/... AS OF 250 PM MONDAY... WEDNESDAY AND WEDNESDAY NIGHT: A STRENGTHENING SURFACE LOW WILL TRACK ALONG THE EASTERN U.S. COAST ON WEDNESDAY. ALL MODELS INDICATE PRECIPITATION SPREADING OVER THE ENTIRE AREA DURING THE DAY WHILE THE LOW IS IN CLOSEST PROXIMITY TO THE NORTH CAROLINA COAST. TIMING AND INTENSITY OF THE PRECIPITATION WILL BE KEY IN DETERMINING WHETHER THERE WILL BE ANY SNOW MIXING IN WITH THE RAIN. FOR NOW... EXPECT THE PRECIP TO BE ALL LIQUID...BUT CANNOT RULE OUT THE CHANCE FOR A FEW WET SNOWFLAKES TO MIX IN...MAINLY THE FAR NORTHWEST FOR THE HOURS AROUND DAYBREAK WHEN TEMPERATURES AND DEWPOINTS WILL BE IN THE MID 30S. CONFIDENCE THAT SNOW WILL FALL IS VERY LOW AT THIS POINT AND IF IT DOES OCCUR IT WILL BE OF LITTLE CONSEQUENCE. DRY AIR WILL BEGIN ADVECTING IN ALOFT AND MIXING DOWN AS THE LOW MOVES AWAY FROM THE REGION...HOWEVER SKIES WILL LIKELY REMAIN MOSTLY CLOUDY AS LOW LEVEL MOISTURE LINGERS. HIGHS WEDNESDAY WILL ALSO BE IMPACTED BY THE PRECIP AND CLOUD COVER...BUT EXPECT MAINLY AROUND 40 DEGREES NORTH TO MID 40S SOUTH. THANKSGIVING DAY/NIGHT: THE BETTER CHANCE OF SEEING SNOW WILL COME ON THURSDAY AS A SHORTWAVE APPROACHES FROM THE NW. THE MODELS INDICATE PRECIPITATION BEING GENERATED WITH THIS DISTURBANCE...AND IF IT OCCURS AFTER MIDNIGHT WHEN TEMPERATURES DROP INTO THE LOW TO MID 30S...SNOW FLURRIES WOULD BE POSSIBLE. WHATEVER PRECIPITATION IS GENERATED SHOULD BE LIGHT...WITH LITTLE IF ANY ACCUMULATION. THE FASTER GFS SOLUTION WOULD FAVOR FLURRIES...WHILE THE SLOWER ECMWF WOULD FAVOR SPRINKLES. OTHERWISE...EXPECT CLOUDY SKIES UNTIL THE S/W EXITS THE REGION...RAPIDLY CLEARING BEHIND IT. WITH PLENTY OF SUN EXPECTED ON THANKSGIVING...EXPECT HIGHS IN THE UPPER 40S NORTH TO MID 50S SOUTH. CONTINUED CLEAR SKIES OVERNIGHT WITH LIGHT NW WINDS WILL YIELD LOWS IN THE MID 20S TO LOW 30S. FRIDAY THROUGH MONDAY: THE UPPER LEVEL FLOW WILL BECOME MORE ZONAL LATE IN THE WEEK AND INTO THE WEEKEND...WITH HIGH PRESSURE TO OUR SOUTH. SURFACE HIGH PRESSURE WILL BUILD IN FROM THE NW ON FRIDAY AND LINGER OVER THE AREA SATURDAY. THE CENTER OF THE HIGH WILL MOVE OUT OVER THE ATLANTIC AND AWAY FROM THE REGION LATE IN THE WEEKEND... HOWEVER IT WILL CONTINUE TO RIDGE WESTWARD INTO THE CAROLINAS THROUGH EARLY NEXT WEEK. MEANWHILE...A COLD FRONT IS EXPECTED TO BECOME STALLED WELL TO OUR NORTH MONDAY AND TUESDAY...HOWEVER NO RAINFALL IS EXPECTED OVER OUR AREA THROUGH THE REMAINDER OF THE PERIOD. MODERATING TEMPERATURES ARE EXPECTED...FROM MID 40S TO AROUND 50 DEGREES ON FRIDAY...TO UPPER 50S TO LOW 60S BY THE END OF THE WEEKEND. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... AS OF 710 PM MONDAY... 24-HR TAF PERIOD: VFR CONDITIONS AND LIGHT/VARIABLE WINDS WILL PREVAIL AT THE INT/GSO TERMINALS THROUGH THE TAF PERIOD. FURTHER EAST IN CLOSE VICINITY TO A STALLED FRONTAL ZONE...SHOWERS AND MVFR/IFR CEILINGS WILL PREVAIL THROUGH THE TAF PERIOD...PARTICULARLY AT THE FAY/RWI TERMINALS. A SOUTHERLY BREEZE AT 5-10 KT THIS EVENING WILL BECOME LIGHT/VARIABLE LATE TONIGHT INTO TUESDAY. LOOKING AHEAD: DETERIORATING CONDITIONS (MVFR/IFR CEILINGS AND RAIN) ARE EXPECTED ACROSS THE ENTIRE AREA TUESDAY NIGHT/WEDNESDAY AS A LOW PRESSURE SYSTEM DEVELOPS ALONG THE STALLED FRONTAL ZONE AND TRACKS NORTHEAST ALONG THE CAROLINA/MID-ATLANTIC COAST. IMPROVEMENT WILL BE DELAYED BY THE APPROACH OF A SECOND UPPER LEVEL DISTURBANCE AND ATTENDANT CHANCE FOR LOW CEILINGS/RAIN WED NIGHT. VFR CONDITIONS WILL RETURN TO THE ENTIRE AREA THU AN PERSIST THROUGH FRI/SAT AS DRY HIGH PRESSURE BUILDS INTO THE REGION FROM THE WEST. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...PWB SHORT TERM...HARTFIELD LONG TERM...KC AVIATION...VINCENT

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