Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 270710 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 210 AM EST TUE JAN 27 2015 .SYNOPSIS...
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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.
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&& .NEAR TERM /THROUGH WEDNESDAY NIGHT/...
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AS OF 905 PM MONDAY... COLD FRONT MAKING SLOW BUT STEADY PROGRESS ACROSS THE WESTERN PIEDMONT THIS EVENING AS EVIDENT OF BLUSTERY NW SFC WINDS IN THE TRIAD AND DEWPOINTS IN THE 20S. COLD FRONT WILL CROSS THE RALEIGH DURHAM AREA THROUGH 10 PM...AND ROCKY MOUNT/WILSON...AND FAYETTEVILLE AROUND MIDNIGHT. INCREASING LOW LEVEL CONVERGENCE AIDING TO INITIATE/SUSTAIN A BAND OF SHOWERS AHEAD OF THE FRONT FROM THE RDU AREA SOUTHWARD TO FORT BRAGG. THESE SHOWERS WILL CONTINUE TO GLIDE SEWD INTO THE COASTAL PLAIN. 00Z UPPER AIR ANALYSIS DEPICTS A STRONG JET (NEAR 150KTS) DIGGING DOWN THE BACK SIDE OF THE UPPER TROUGH. THIS ENERGY WILL CAUSE THE UPPER TROUGH TO DEEPEN FURTHER ACROSS THE EASTERN SEABOARD OVERNIGHT...LEADING TO DEEP SFC CYCLOGENESIS OFF THE SOUTHERN NEW ENGLAND COAST. THIS DEEPENING SFC LOW WILL PULL COLDER AIR FARTHER SOUTH INTO CENTRAL NC OVERNIGHT. PATCHY LIGHT RAIN ROTATING SOUTHWARD FROM VA INTO NE NC WILL EVENTUALLY MIX WITH OR CHANGE TO SNOW FLURRIES OR SNOW SHOWERS ACROSS THE FAR NE PIEDMONT AND THE NORTHERN COASTAL PRIOR TO DAYBREAK. CANNOT RULE OUT A LIGHT DUSTING ON THE TOP OF CARS OR WOODEN DECKS...BUT THE EXPECTED LIGHT PRECIP INTENSITY AND RELATIVELY WARM GROUND SUGGEST NO ACCUMULATION ON THE GROUND OR ROAD SURFACES. BLUSTERY NW WINDS OVERNIGHT WILL ADVECT A DRIER COLDER AIR MASS INTO CENTRAL NC. THIS WIND SHOULD EVAPORATE THE BULK OF RESIDUAL MOISTURE LEFTOVER FROM RECENT RAINFALL. THUS AS TEMPS DROP TO NEAR OR SLIGHTLY BELOW FREEZING IN THE PIEDMONT TOWARD DAYBREAK...NOT EXPECTING WIDESPREAD BLACK ICE SCENARIO THOUGH COULD SEE A SLICK SPOT OR TWO ON LESS TRAVELED ROADS...ESPECIALLY WHERE RAINWATER NORMALLY COLLECTS AND IS SHELTERED FROM THE WIND. -WSS THERE MAY BE A LINGERING SNOW FLURRY OR SHOWER MAINLY NORTH AND EAST OF RDU THROUGH LATE MORNING... THEN HIGH PRESSURE WILL SLOWLY BUILD IN FROM THE WEST. HOWEVER... THE MID/UPPER TROUGH WILL MAINTAIN INFLUENCE ON MUCH OF THE REGION AS IT WILL BE SLOW TO PULL OUT TO THE NE. THE SKIES WILL BECOME PARTLY CLOUDY NE TO MOSTLY SUNNY SW AND WEST WITH BREEZY CONDITIONS IN THE AFTERNOON. HIGHS IN THE 40S. NORTHWEST WINDS 10-20 MPH WILL PRODUCE A CHILLY WIND CHILL IN THE 20S AND 30S THROUGHOUT THE DAY. CLEAR AND COLD CONDITIONS UNDER HIGH PRESSURE ARE EXPECTED TUESDAY NIGHT WITH LIGHT WINDS. LOWS IN THE 20S. -BADGETT WED/WED NIGHT: CLEAR SKIES...DRY CONDITIONS AND BELOW NORMAL TEMPS WILL PREVAIL IN THE WAKE OF THE NEW ENGLAND NOR`EASTER AS A SHORTWAVE RIDGE /SFC HIGH/ BUILDS EASTWARD ACROSS THE APPALACHIANS (WED) AND CAROLINAS (WED NIGHT). EXPECT HIGHS 40-45F...COOLEST NE COASTAL PLAIN. STRONG RADIATIONAL COOLING WOULD SUGGEST LOWS IN THE LOWER/MID 20S WED NIGHT...THOUGH ADDITIONAL SHORTWAVE ENERGY WILL DIG SOUTHEAST INTO THE OHIO VALLEY IN NW FLOW ALOFT AND SCATTERED TO BROKEN UPPER LEVEL CEILINGS WILL BE POSSIBLY BY SUNRISE...ESP N/NW PORTIONS OF CENTRAL NC. IF UPPER LEVEL CEILINGS ARRIVE EARLY AND/OR THICK ENOUGH...LOWS COULD BE A FEW DEGREES WARMER THAN WOULD OTHERWISE BE THE CASE. -BV
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&& .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
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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.
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&& .LONG TERM /FRIDAY THROUGH MONDAY/...
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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
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&& .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 100 AM TUESDAY... 24 HOUR TAF PERIOD: CONDITIONS AT THIS HOUR ARE GENERALLY SPLIT BETWEEN VFR IN THE WEST WHERE IT IS CONSIDERABLY DRIER AND MVFR IN THE EAST WHERE MORE MOISTURE IS PRESENT IN THE LOWER LEVELS. MVFR CONDITIONS ARE DUE TO LOWER CEILINGS WITH VISIBILITIES EVERYWHERE COMING IN AT 10 SM. THERE CONTINUE TO BE A FEW WIND GUSTS OUT THERE UP TO 20 KTS...PARTICULARLY IN THE NORTHEAST WHICH MAKES SINCE AS THE PRESSURE GRADIENT THERE INCREASES CLOSER TO THE LOW OFFSHORE. WINDS ARE GENERALLY OUT OF THE NORTHWEST AND WILL STAY THAT WAY THROUGH THE TAF PERIOD. GUSTS ARE EXPECTED TO RELAX AFTER 9Z. AS DRIER AIR CONTINUES TO WORK IN FROM THE WEST CONDITIONS WILL IMPROVE BACK TO VFR AND REMAIN THERE THROUGH THE PERIOD. GUSTS OF 15-20 KTS WILL BE PREVALENT AGAIN LATER IN THE AFTERNOON. THERE IS A CHANCE FOR A LINGERING RAIN SHOWER OR EVEN A FEW SNOW FLURRIES AS WE CONTINUE THROUGH THE MORNING WITH THE MOST LIKELY LOCATION BEING THE NORTHEAST. ONE OTHER NOTE...PILOT REPORTS HAVE BEEN COMING IN AROUND KRDU AND POINTS NORTH FOR LIGHT TO MODERATE ICING FROM 4-12 KFT. 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. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...WSS/BADGETT/VINCENT SHORT TERM...HARTFIELD LONG TERM...HARTFIELD AVIATION...ELLIS

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