Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 251457 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 955 AM EST TUE NOV 25 2014 .SYNOPSIS...A STATIONARY FRONT WILL LINGER OVER EASTERN NORTH CAROLINA TODAY. LOW PRESSURE IS EXPECTED TO TRACK NE ALONG THE CAROLINA AND MIDATLANTIC COAST TONIGHT AND WEDNESDAY. HIGH PRESSURE WILL BUILD IN FROM THE WEST FROM THANKSGIVING DAY AND REMAIN IN CONTROL OF OUR WEATHER THROUGH THE HOLIDAY WEEKEND. && .NEAR TERM /THROUGH WEDNESDAY/... AS OF 955 AM TUESDAY... REST OF TODAY: LIGHT TO MDT RAIN CONTINUES TO FALL OVER OUR SE CWA EASTWARD THROUGH THE COASTAL AREA THIS MORNING... FUELED BY HIGH PW VALUES (OVER 150% OF NORMAL) ALONG A TROPICAL-SOURCE MOISTURE PLUME... WEAK MID LEVEL DPVA... AND WAVES OF ENHANCED UPPER DIVERGENCE WITHIN THE RIGHT ENTRANCE REGION OF A STRONG (160+ KT) JET RUNNING FROM THE NRN GULF STATES TO THE ST LAWRENCE VALLEY. HI- RES NEAR TERM MODEL OUTPUT AS WELL AS EXTRAPOLATION OF UPSTREAM ECHOES SUGGESTS THAT THE WESTERN EDGE OF THE STEADY RAIN SHIELD WILL BRIEFLY NUDGE EASTWARD AND HOLD OVER THE NEXT FEW HOURS... RESULTING IN A RELATIVE LULL IN THE TRIANGLE AREA... ALTHOUGH ISOLATED PATCHES OF VERY LIGHT RAIN WILL PERSIST OVER THE EASTERN PIEDMONT... WHILE STEADY RAIN WILL HOLD OVER ERN CUMBERLAND CO THROUGH SAMPSON AND WAYNE COUNTIES. BUT BY LATE THIS AFTERNOON... WE SHOULD SEE ANOTHER WESTWARD BULGING OF THE RAIN SHIELD... ALREADY SEEN MOVING INTO EAST- CENTRAL GA... AND CURRENT FORECAST TRENDS OF POPS BACK UP TO CATEGORICAL FROM SOUTH TO NORTH STARTING MID-LATE AFTERNOON LOOKS VERY GOOD. THE COLD FRONT CONTINUES TO PLOD ESE THROUGH CENTRAL NC... HAVING JUST PASSED THROUGH WARRENTON / SILER CITY / ALBEMARLE... CHARACTERIZED BY A WIND SHIFT TO NW AND DROP IN DEWPOINTS. GIVEN THE THICK CLOUD SHIELD AND IMMINENT COLD AIR ADVECTION... TEMPS SHOULD MOVE UP JUST A FEW DEGREES FROM THE THEIR CURRENT READINGS... AND IN FACT THE WRN CWA MAY HAVE ALREADY SEEN ITS DAYTIME HIGH. EXPECT AREAWIDE HIGHS TO BE IN THE LOW 60S... BUT WITH STEADY OR SLOWLY FALLING READINGS POSSIBLE THIS AFTERNOON. -GIH TONIGHT...STRENGTHENING MID LEVEL TROUGH CROSSING/LIFTING E-NE ACROSS THE DEEP SOUTH WILL INDUCE A SURFACE WAVE TO FORM ON THE FRONT THIS EVENING. THIS STRENGTHENING SURFACE LOW WILL INCREASE LOW LEVEL CONVERGENCE ALONG THE STALLED FRONT OVER THE COASTAL PLAIN. ALOFT...A 805MB LOW IS EXPECTED TO LIFT NE FROM THE SAVANNAH RIVER VALLEY NEWD UP ALONG THE I-95 CORRIDOR. THIS FEATURE WILL ALSO AID TO INCREASE LOW LEVEL CONVERGENCE. LIFT WILL BE RATHER DEEP THROUGH THE COLUMN THANKS TO 160+KT JET LIFTING NE ALONG THE SPINE OF THE APPALACHIANS. FINALLY...ATMOSPHERE EXPECTED TO BE QUITE MOIST FOR THIS TIME OF YEAR WITH PRECIP WATER VALUES AROUND 1.5 INCHES OVER THE SANDHILLS AND COASTAL PLAIN. THESE COMBINED VALUES SUGGEST WIDESPREAD MODERATE RAIN LATE THIS EVENING INTO EARLY WEDNESDAY MORNING WITH THE MOST PERSISTENT MODERATE-BRIEFLY HEAVY RAINFALL IN VICINITY OF TEH 850MB LOW TRACK (I-95). PLAN TO HAVE CATEGORICAL POPS MOST LOCATIONS WITH RAINFALL AMOUNTS TONIGHT VARYING FROM AROUND A HALF INCH IN THE NW PIEDMONT TO MORE THAN AN INCH ALONG AND EAST OF HIGHWAY 1. CIRCULATION AROUND THE DEEPENING SFC LOW WILL RESULT IN A NLY FLOW OVER CENTRAL NC. THS FLOW WILL ADVECT COOLER AIR INTO OUR REGION...WITH TEMPS FALLING INTO THE 40S. WEDNESDAY...WIDESPREAD RAIN WILL GRADUALLY DIMINISH FROM THE SW LATE MORNING-AFTERNOON AS THE SFC-850MB LOW LIFTS OFF TO THE NE. RESULTANT NW FLOW IN THE WAKE OF THE DEPARTING LOW WILL AID TO DIMINISH RAIN AND GRADUALLY DECREASE CLOUD COVERAGE. CLEARING WILL BE TEMPORARY AS FAST APPROACHING UPPER LEVEL DISTURBANCE WILL CAUSE AN UPTICK IN CLOUDS ACROSS THE NORTHERN PIEDMONT PRIOR TO SUNSET. MAX TEMPS WILL JUST BE A FEW DEGREES WARMER THAN PREVIOUS NIGHTS LOWS DUE TO RAIN AND CLOUD COVERAGE. MAX TEMPS MID 40S NORTH TO AROUND 50 SE. -WSS && .SHORT TERM /WEDNESDAY NIGHT AND THANKSGIVING DAY/... AS OF 310 AM TUESDAY... S/W ENERGY CURRENTLY MOVING INTO THE NORTHWEST U.S. WILL DIVE SOUTHEASTWARD AND ACROSS OUR AREA ON WEDNESDAY NIGHT INTO THURSDAY. MODELS HAVE TRENDED A BIT FURTHER SOUTHWARD WITH THE CORE OF THE VORT MAX... NOW TRACKING ACROSS CENTRAL NC. A PREFERRED TRACK FOR PRECIP WOULD BE JUST TO THE SOUTH OF CENTRAL NC. HOWEVER... STILL EXPECT WE MAY SEE SOME PRECIP ACROSS THE NORTHERN HALF OF THE CWA NOW... WEDNESDAY NIGHT/INTO THURSDAY MORNING. WITH A LACK OF ANY GOOD COLD AIR IN PLACE THOUGH... SURFACE TEMPS ARE EXPECTED TO REMAIN ABOVE FREEZING... WITH THE NAM/GFS/ECMWF SHOWING SURFACE WETBULB TEMPS ABOVE FREEZING EVEN... GENERALLY IN THE MID 30S AT THE WORST WHEN THE CHANCE FOR PRECIP IS. GIVEN THIS ALONG WITH THE LOWEST SEVERAL THOUSAND FEET OF THE ATMO IS FORECAST TO BE ABOVE FREEZING THE CHANCE FOR ANY ACCUMULATING SNOW IS QUITE LOW. HOWEVER... GIVEN THE STRENGTH OF THE DISTURBANCE AND RESULTANT STEEP MID LEVEL LAPSE RATES... THINK WE COULD SEE SOME SNOW MIX IN ACROSS OUR FAR NORTHERN PIEDMONT WITH THE MOST INTENSE PRECIP. THUS... ANY SNOWFALL WOULD BE DRIVEN BY INTENSITY/RATES. GIVEN THE EXPECTED ABOVE NORMAL TEMPS AND RECENT WARM TEMPS DO NOT EXPECT ANY PROBLEMS FROM ANY SNOW. FOR GO WITH A CHANCE FOR RAIN ACROSS THE NORTHERN PIEDMONT/SLIGHT CHANCE FURTHER SOUTH NEAR THE U.S. 64 CORRIDOR... WITH ONLY A SLIGHT CHANCE FOR SNOW ACROSS THE FAR NORTHERN PIEDMONT. THE DISTURBANCE IS EXPECTED TO QUICKLY MOVE ACROSS THE AREA... ANY PRECIP TO THE EAST OF THE AREA BY EARLY AFTERNOON. EXPECT LOW TEMPS WILL GENERALLY BE IN THE MID TO UPPER 30S... THANKS TO THE EXPECTED CLOUD COVER WITH THE APPROACHING SYSTEM. HIGH TEMPS ON THURSDAY WILL DEPEND ON THE HOW MUCH IF ANY PRECIP WE GET AND HOW QUICKLY WE THE SYSTEM DEPARTS/SCATTERING CLOUDS AND SEEING SOME SUN. HAVE TRENDED THE HIGHS ACROSS THE NORTH TO THE LOWER SIDE OF GUIDANCE THOUGH GIVEN THE TRACK OF THE DISTURBANCE. FOR NOW WILL GO WITH HIGH TEMPS THURSDAY RANGING FROM THE MID TO UPPER 40S NORTH/NORTHEAST TO THE MID 50S FAR SOUTH. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... AS OF 310 AM TUESDAY... SURFACE HIGH PRESSURE WILL BUILD EASTWARD AND INTO THE AREA LATE WEEK... BEFORE SHIFTING TO THE SOUTH AND EAST OF CENTRAL NC BY THE WEEKEND. MID LEVEL HEIGHTS ARE FORECAST TO RISE BY LATE WEEK INTO THE WEEKEND... AS FLOW BECOMES MORE ZONAL ACROSS THE SOUTHERN HALF OF THE COUNTRY. MEANWHILE... A MID LEVEL RIDGE IS FORECAST TO BUILD NORTHWARD AND NUDGE INTO OUR AREA... WHICH WILL HELP TO KEEP ANY NORTHERN STREAM S/W ENERGY TO THE NORTH OF THE AREA NEAR THE U.S/CANADIAN BORDER. A TRAILING DRY COLD FRONT HOWEVER... IS EXPECTED TO APPROACH THE AREA BY LATE IN THE FORECAST PERIOD... IN BACKDOOR FASHION ON MONDAY. EXPECT TEMPS WILL BE BELOW NORMAL AND CHILLY UNTIL WE SEE A WARMING RETURN FLOW ON SATURDAY. THUS... EXPECT HIGHS IN THE 40S ON FRIDAY WITH LOWS FRIDAY AND SATURDAY MORNING IN THE 20S TO LOWER 30S. HIGHS FOR THE REMAINDER OF THE MEDIUM RANGE ARE EXPECTED TO BE IN THE 50S AND 60S WITH LOWS IN THE UPPER 30S TO 40S. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 635 AM TUESDAY... A NEARLY STATIONARY SURFACE FRONT ACROSS THE PIEDMONT OF CENTRAL NC COUPLED WITH A MOIST SW FLOW ALOFT WILL CAUSE EXTENSIVE CLOUDINESS AND PATCHES OF LIGHT RAIN ACROSS BASICALLY THE EASTERN HALF OF CENTRAL NC THROUGH EARLY THIS AFTERNOON. CLOUD HEIGHTS WILL VARY BETWEEN MVFR AND VFR CATEGORIES THOUGH WIDESPREAD MVFR CEILINGS EXPECTED LATE THIS AFTERNOON. AN AREA OF LOW PRESSURE WILL DEVELOP OFF THE GA COAST LATE TODAY AND TRACK NE ALONG THE CAROLINA COAST LATE TONIGHT AND WEDNESDAY. THIS WEATHER SYSTEM WILL SPREAD ADDITIONAL MOISTURE INTO CENTRAL NC... RESULTING IN WIDESPREAD IFR/MVFR CEILINGS AND AREAS OF RAIN...ESPECIALLY ALONG AND EAST OF HIGHWAY 1 AFFECTING THE KRDU...KFAY...AND KRWI TERMINALS. THIS LOW PRESSURE SYSTEM WILL PULL AWAY FROM OUR REGION WEDNESDAY NIGHT...PROMPTING A SLOW IMPROVEMENT IN CEILINGS. A FAST MOVING UPPER LEVEL SYSTEM WILL TRAVERSE ACROSS NORTHERN NC LATE WEDNESDAY NIGHT THROUGH EARLY THURSDAY...PROLONGING MVFR CEILINGS A BIT LONGER AT KGSO/KINT/KRDU. THIS SYSTEM WILL EXIT CENTRAL NC AROUND MID DAY THURSDAY. HIGH PRESSURE WILL BUILD INTO THE CAROLINAS THURSDAY NIGHT INTO FRIDAY...INITIATING A PROLONGED PERIOD OF VFR CONDITIONS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...HARTFIELD/WSS SHORT TERM...BSD LONG TERM...BSD AVIATION...WSS

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