Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 271145 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 645 AM EST TUE JAN 27 2015 .SYNOPSIS...STRONG LOW PRESSURE OFF NEW ENGLAND THIS MORNING WILL LIFT NORTHEAST AWAY FROM OUR AREA TODAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST THIS AFTERNOON THROUGH EARLY THURSDAY. ANOTHER CLIPPER LOW PRESSURE SYSTEM WILL SWING BY JUST TO OUR NORTH LATE THURSDAY THROUGH THURSDAY NIGHT... THEN HIGH PRESSURE WILL AGAIN BUILD INTO OUR AREA FROM THE NORTHWEST ON FRIDAY. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... AS OF 240 AM TUESDAY... TODAY AND TONIGHT: FRONTAL SYSTEM IS CURRENTLY MOVING THROUGH THE AREA AS LOW PRESSURE CONTINUES TO DEEPEN ACROSS THE DELMARVA. THE CWA IS CURRENTLY SPLIT BETWEEN DRIER AIR TO THE WEST OF ROUTE 1 AND MORE MOISTURE TO THE EAST. A BAND OF PRECIPITATION HAS SET UP ALONG WHAT APPEARS TO BE THE FRONTAL BOUNDARY AND HAS BROUGHT SOME SCATTERED REPORTS OF A RAIN/SNOW MIX FROM PERSON COUNTY DOWN THROUGH WAKE COUNTY WITH MOSTLY RAIN OR DRIZZLE SOUTH OF THERE. THIS BAND WILL MOVE GRADUALLY EASTWARD THROUGH THE EARLY MORNING HOURS TOWARDS TEH I-95 CORRIDOR AND THE EASTERN TIER OF COUNTIES. SCATTERED REPORTS OF LIGHT SNOW OR RAIN WILL CONTINUE THROUGH THE MORNING BEFORE MOST LOCALES DRY OUT. THE THREAT FOR SNOW SHOULD END AFTER 12Z AS RAP FORECAST SOUNDINGS INDICATE SIGNIFICANT DRYING IN THE SNOW GROWTH ZONE. NO ACCUMULATION IS EXPECTED OR ANY IMPACTS FROM THE SNOW ASIDE FROM A POTENTIAL DUSTING ON ELEVATED SURFACES AT BEST AS SOIL TEMPERATURES ARE STILL NEAR 40 DEGREES. THIS SETUP HAS ALSO CAUSED A SPLIT IN CLOUD COVER WITH AREAS UNDER AND EAST OF THE PRECIPITATION BAND EXPERIENCING MAINLY MVFR CEILINGS WITH VFR CONDITIONS BACK TO THE WEST. A FEW WIND GUSTS STILL OUT THERE UP TO 20 KTS OR SO OUT OF THE NORTHWEST. GUSTS MAY DIE OFF TOWARDS SUNRISE BUT WILL PICK UP AGAIN LATER THIS AFTERNOON. TEMPERATURES THIS AFTERNOON IN THE LOW TO MID 40S NE TO SW AS CLOUDS LINGER LONGER AND COLD AIR ADVECTION IS MORE PRONOUNCED IN THE NORTHEAST. EXPECT DRYING TO CONTINUE INTO TONIGHT WITH CLEARING SKIES BUT WINDS REMAINING 5-10 KTS SO NOT EXACTLY GREAT FOR RADIATIONAL COOLING BUT TEMPS WILL STILL MANAGE TO DROP INTO THE MIDDLE 20S WITH THE CHANGE IN AIRMASS. WEDNESDAY AND WEDNESDAY NIGHT: A DRY DAY EXPECTED FOR WEDNESDAY AS CENTRAL NC IS SANDWICHED BETWEEN THE EXITING BLIZZARD TO THE NORTHEAST AND INCOMING HIGH PRESSURE TO THE NORTHWEST. SURFACE PRESSURE GRADIENT WILL RELAX A LITTLE BUT STILL A GOOD COLD AIR ADVECTION REGIME BOTH AT THE SURFACE AND ALOFT ON THE BACK SIDE OF THE UPPER LEVEL TROUGH. THIS WILL KEEP TEMPS DOWN IN THE LOW TO MID 40S...ABOUT 10 DEGREES BELOW NORMAL FOR THIS TIME OF YEAR. WINDS 5- 10 KTS OUT OF THE NORTH VEERING TO NORTHEASTERLY LATER IN THE DAY. CLOUDS WILL GRADUALLY INCREASE IN THE NORTHWEST ON WEDNESDAY NIGHT AS THE NEXT LOW PRESSURE SYSTEM MOVES INTO THE OHIO VALLEY. THIS WILL HELP TO KEEP LOW TEMPERATURES UP IN THE TRIAD. GENERALLY MID 20S BUT POSSIBLY SOME LOWER 20S IN OUR EASTERN NORMALLY COLD ZONES. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... AS OF 200 AM TUESDAY... THU/THU NIGHT: THE GREAT LAKES SHORTWAVE TROUGH WILL TRACK ESE THEN EASTWARD ACROSS THE NORTHEAST/MIDATLANTIC STATES... TRACKING THROUGH THE BASE OF THE POLAR LOW OVER HUDSON BAY... WHILE ITS CORRESPONDING SURFACE LOW CROSSES THE OH VALLEY AND MIDATLANTIC COAST. AFTER A CHILLY MORNING WITH THE SURFACE RIDGE OVERHEAD... INCREASING SOUTHERLY LOW LEVEL FLOW AS THE HIGH SHIFTS SSE WILL ALLOW FOR A MODEST RECOVERY IN THICKNESSES... BUT STILL BELOW NORMAL... AND THE TEMP RISE WILL BE HINDERED BY THICKENING AND LOWERING CLOUDS WITH APPROACHING WEAK MID LEVEL DPVA AND LOW LEVEL FRONTAL ZONE. BUT MODELS STILL SHOW PW VALUES JUST BARELY REACHING ABOVE NORMAL... AND GFS/NAM BUFR FORECAST SOUNDINGS SHOW A DRY SUBCLOUD LAYER BELOW 850 MB THROUGH THU. MODEL QPF IS ALSO SCANT WITH THE GFS/NAM/SREF MEAN STAYING DRY OVER CENTRAL NC THROUGH THU NIGHT. AFTER 00Z THE COLUMN STARTS TO DRY OUT ALOFT BEHIND THE 700 MB TROUGH... AND JUST AHEAD OF THE SURFACE FRONT WHICH IS EXPECTED TO SWEEP EAST THROUGH CENTRAL NC AFTER MIDNIGHT. WILL TRIM BACK EXISTING SLIGHT CHANCE POPS A BIT... FOCUSING THEM LATE THU AFTERNOON UNTIL SHORTLY AFTER MIDNIGHT... HOWEVER AM RELUCTANT TO REMOVE THEM ENTIRELY AS THE ECMWF CONTINUES TO GENERATE LIGHT PRECIP LATE THU AFTERNOON AND THU EVENING. EXPECT HIGHS THU IN THE MID 40S TO AROUND 50. LOWS THU NIGHT 32-38. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 200 AM TUESDAY... FRI-SAT: THE MID LEVEL TROUGH AXIS WILL BE SWINGING TO OUR EAST FRI MORNING WITH THE SURFACE COLD FRONT PUSHING OFF THE NC COAST. NW LOW LEVEL FLOW WILL BRING IN COOLER AIR AS HIGH PRESSURE INITIALLY CENTERED OVER NRN MINN DRIFTS SOUTHEAST... BUILDING INTO AND OVER THE MIDATLANTIC THROUGH VA/ERN NC THROUGH SAT. SHOULD SEE MOSTLY CLEAR SKIES FRI/FRI NIGHT... FOLLOWED BY INCREASING HIGH THIN CLOUDS SAT AS WE START TO SEE INITIAL ENERGY EJECTING FROM THE DESERT SW LOW TRACK EASTWARD WITHIN CONFLUENT NW MID LEVEL FLOW. WITH FALLING THICKNESSES FRI... EXPECT BELOW-NORMAL HIGHS IN THE MID 40S TO LOWER 50S. LOWS FRI NIGHT IN THE MID 20S... THEN WITH SUCH A CHILLY START AND THE CANADIAN-SOURCE AIR MASS BUILDING IN YIELDING THICKNESSES AT LEAST 30 M BELOW NORMAL... HIGHS SAT SHOULD ONLY BE IN THE 40-45 RANGE. SAT NGT-MON: A LOT OF UNCERTAINTY IN THE DETAILS PERSISTS THIS MORNING... HOWEVER IT`S LOOKING MORE LIKELY THAT WE`RE ENTERING INTO A PERIOD OF MORE ACTIVE WEATHER DOMINATED BY SOUTHERN STREAM ENERGY BUT WITH POTENTIAL INJECTIONS OF COOLER AIR FROM THE NORTHERN STREAM. A NRN STREAM WAVE DROPPING SOUTHEAST FROM MT THROUGH THE CENTRAL PLAINS WILL MERGE WITH SOUTHERN STREAM ENERGY EMANATING FROM THE LOW OVER NRN MEX SAT NIGHT/SUN... BRINGING MID LEVEL DPVA INTO NC SUN/SUN NIGHT. THE SHIFTING OF THE SURFACE HIGH ESE OFF THE COAST WILL ALLOW A MOIST RETURN FLOW OFF THE GULF INTO THE GULF/MIDSOUTH AND SOUTHEAST STATES... AS SURFACE LOW PRESSURE DEVELOPS ALONG THE BAROCLINIC ZONE NEAR THE NW GULF COAST AND TRACKS NORTHEAST TOWARD NC. THE GFS/ECMWF BRING PRECIP INTO WRN NC BY MIDDAY SUN... THEN SPREAD IT EASTWARD THROUGH CENTRAL NC SUN NIGHT INTO EARLY MON MORNING. BOTH THE GFS/ECMWF SHOW A MILLER TYPE-B CYCLOGENESIS PATTERN BUT WITH VARIED LOW PLACEMENT... WITH THE ECMWF DEPICTING A FURTHER-SOUTH TRIPLE POINT LOW TRACK VERSUS THE GFS. THE LATEST RUNS SHOWS SUFFICIENTLY WARM LOW- AND MID-LEVEL THICKNESSES TO SUPPORT AN ALL-RAIN EVENT... BUT GIVEN THIS PATTERN... WILL NEED TO WATCH MODEL TRENDS CAREFULLY IN THE COMING DAYS. WITH OTHERWISE GOOD MODEL AGREEMENT ON TIMING AND THE MID-LEVEL PATTERN... WILL BUMP UP POPS... FOCUSING THE HIGHER CHANCES SUN AFTERNOON THROUGH SUN NIGHT... TAPERING DOWN WEST-TO-EAST MON MORNING AS THE DAMPENING MID LEVEL SHORTWAVE TROUGH SHIFTS EAST OVER THE MIDATLANTIC/ NORTHEAST WITH SURFACE FRONTAL PASSAGE THROUGH NC. EXPECT IMPROVING WEATHER LATE MON WITH ANOTHER CANADIAN HIGH CENTERED OVER THE MIDWEST BUILDING INTO OUR AREA. EXPECT BELOW NORMAL TEMPS THROUGH SUN NIGHT... WITH MORE UNCERTAINTY FOR HIGHS ON MON AS MUCH WILL DEPEND ON WHETHER OR NOT WE GET INTO THE WARM SECTOR BEFORE FRONTAL PASSAGE. WILL KEEP TEMPS BELOW NORMAL FOR NOW BUT IF MODEL WARMING TRENDS HOLD... MAY NEED TO BUMP UP MON HIGHS QUITE A BIT IN LATER FORECASTS. -GIH && .AVIATION /12Z TUESDAY THROUGH SATURDAY/...
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AS OF 645 AM TUESDAY... 24 HOUR TAF PERIOD: LIGHT SNOW OVERSPREADING NORTHEASTERN AREAS OF THE CWA THIS MORNING. SNOW IS CURRENTLY MOVING OUT OF THE KRWI AREA AND IS NOW CONFINED NORTH AND EAST. ELSEWHERE PRECIPITATION HAS LARGELY ENDED OUTSIDE OF A FEW SNOW FLURRIES. WINDS ARE LIGHT AND VARIABLE AT THIS HOUR BUT WILL BE PICKING BACK UP TO 5-10 KTS OUT OF THE NORTHWEST THIS MORNING AND THEN GUSTING TO 20 KTS THIS AFTERNOON. SOME MVFR CEILINGS STILL IN PLACE IN AREAS WHERE LIGHT SNOW IS STILL FALLING. ELSEWHERE VFR CEILINGS ARE PREVAILING AND SKIES WILL CONTINUE TO CLEAR AS THE DAY PROGRESSES WITH THE EXCEPTION OF THE NORTHEASTERN AREAS WHERE CLOUDS WILL LINGER. LONG TERM: THE NEXT THREAT TO AVIATION CONDITIONS WILL BE THURSDAY NIGHT INTO FRIDAY MORNING AS A FRONTAL SYSTEM CROSSES THE AREA AND THEN ANOTHER SYSTEM SUNDAY INTO MONDAY.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...ELLIS SHORT TERM...HARTFIELD LONG TERM...HARTFIELD AVIATION...ELLIS

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