Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 251820 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 120 PM EST TUE NOV 25 2014 .SYNOPSIS...
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A STATIONARY FRONT WILL HOLD ALONG THE CAROLINA COAST TONIGHT THROUGH WEDNESDAY MORNING... AS LOW PRESSURE TRACKS NORTHEAST ALONG THE FRONT NEAR THE SOUTHEAST AND CAROLINA COAST. THIS LOW WILL MOVE NORTHEAST AWAY FROM THE AREA WEDNESDAY AFTERNOON. ANOTHER LOW PRESSURE CENTER WILL CROSS THE REGION FROM WEST TO EAST WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING. THEN... HIGH PRESSURE WILL BUILD IN FROM THE WEST FROM THANKSGIVING AFTERNOON THROUGH THE HOLIDAY WEEKEND.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 120 PM TUESDAY... REST OF TODAY: LIGHT TO MDT RAIN CONTINUES TO FALL OVER OUR SE AND FAR SRN CWA EASTWARD THROUGH THE COASTAL AREA... 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. WHILE THE BACK (NW) EDGE OF THE STEADY RAIN WILL CONTINUE TO WAVER BACK AND FORTH ONE TO TWO ROWS OF COUNTIES... HI-RES NEAR TERM MODEL OUTPUT (INCLUDING THE WRF-NMM/ARW AND HRRR) SUPPORTS HIGH RAIN CHANCES CONTINUING OVER THE SOUTHEAST CWA (SE OF HIGHWAY 1) FOR THE REST OF THE AFTERNOON WITH MORE PATCHY OR SPORADIC LIGHT RAIN A BIT FURTHER INLAND... AND NEXT TO NOTHING OVER THE TRIAD. THE COLD FRONT... NOW POSITIONED FROM JUST EAST OF ROCKY MOUNT TO SANFORD TO JUST SE OF MONROE... CONTINUES TO PLOD ESE THROUGH CENTRAL/ERN NC... CHARACTERIZED BY A WIND SHIFT TO NW AND DROP IN DEWPOINTS. THIS FRONT WILL CONTINUE ITS SOUTHEASTWARD PROGRESS BEFORE SETTLING AT THE COAST BEFORE 00Z. TEMPS IN THE MID 50S TO LOW 60S WILL REMAIN STEADY OR FALL SLOWLY THROUGH SUNSET. FOR TONIGHT: THE LARGE SCALE MEAN TROUGH COVERING THE CENTRAL/ERN CONUS WILL KEEP THE WEATHER UNSETTLED. THE FRONTAL ZONE WILL HOLD OVER COASTAL CAROLINAS OVERNIGHT... AS SURFACE LOW PRESSURE FORMS OVER THE FAR NE GULF AND TRACKS NNE ACROSS NE FL AND ALONG THE SE COAST OVERNIGHT... TO A POSITION NEAR THE SRN NC COAST BY 12Z WED (THE GFS IS A TAD FASTER THAN THE NAM/ECMWF). A SECONDARY INVERTED TROUGH WILL EXTEND FROM THE DEVELOPING LOW THIS EVENING UP THROUGH WRN NC... AND THIS WILL HELP FOSTER RAINFALL DEVELOPMENT FARTHER WEST AND A BIT EARLIER THAN IT WOULD OTHERWISE WITH JUST A COASTAL LOW IN PLAY. WIDESPREAD RAIN IS EXPECTED TO SPREAD INTO SRN PARTS OF CENTRAL NC STARTING SOON AFTER SUNSET BEFORE SPREADING NORTHWARD OVER THE ENTIRE CWA... PERSISTING FROM MID EVENING THROUGH THE OVERNIGHT HOURS. THIS RAIN WILL BE INSTIGATED BY THIS TROUGH AND THE APPROACH OF THE LOW... IN CONJUNCTION WITH DEEP MOISTENING AND STRENGTHENING FORCING FOR ASCENT VIA DPVA (AS STRONG VORTICITY NEAR EL PASO DIVES THROUGH THE BASE OF THE MEAN TROUGH AND TOWARD THE SRN APPALACHIANS LATE TONIGHT)... STRONG HEIGHT FALLS (~150 M)... STRENGTHENING MOIST UPGLIDE (ESPECIALLY EAST HALF)... POTENTIAL BANDED PRECIP IN THE WEST... AND INTENSIFYING UPPER DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A STRENGTHENING JET FROM THE GULF STATES TO THE CANADIAN MARITIMES. LATEST MODELS AND UPSTREAM PRECIP SUPPORT THE PREVIOUS TRENDS TOWARD CATEGORICAL PRECIP STARTING MID TO LATE EVENING... AND SEE NO REASON TO DEVIATE FROM THIS. LOW TEMPS ARE TOUGH AS DEWPOINTS HAVE YET TO FALL IN THE EAST (STILL IN LOW 60S) BUT HAVE SLIPPED INTO THE 30S IN THE NW CWA. WILL LEAN TOWARD STATISTICAL GUIDANCE WHICH SUPPORTS LOWS OF 39-48... CLOSE TO THE EARLIER FORECAST. -GIH
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&& .SHORT TERM /WEDNESDAY THROUGH THANKSGIVING DAY/...
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AS OF 310 AM TUESDAY... 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 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. -BSD
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&& .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 /18Z TUESDAY THROUGH SUNDAY/... AS OF 1200 PM TUESDAY... EXPECTED AVIATION CONDITIONS: POOR AT EASTERN TERMINALS... FAIR EARLY THEN BECOMING POOR TONIGHT AT WESTERN TERMINALS. PRIMARY AVIATION CONCERNS OVER THE NEXT 24 HRS: MVFR TO IFR CIGS PERSISTING AT FAY/RDU/RWI AND SPREADING FROM SE TO NW AFFECTING ALL CENTRAL NC TAF SITES STARTING 21Z-23Z AND PERSISTING OVERNIGHT. ALSO... MVFR/ IFR VSBYS IN RAIN ESPECIALLY RDU/RWI/FAY TONIGHT-WED... AND BRISK GUSTY SURFACE WINDS FROM NORTH TONIGHT 05Z-11Z AND FROM THE NW 11Z- 18Z WED AT ALL SITES. CONFIDENCE: MEDIUM THROUGH 00Z... THEN HIGH AFTER 00Z. A COLD FRONT PUSHING SLOWLY ESE THROUGH CENTRAL NC WILL SETTLE OVER COASTAL NC BY EVENING. LOW PRESSURE WILL FORM OVER NRN FL AND TRACK NE ALONG THE FRONT ALONG THE SE AND CAROLINA COAST TONIGHT THROUGH WED MORNING WHILE STRENGTHENING... THEN MOVE NORTH TOWARD NEW ENGLAND WED AFTERNOON. STEADY RAIN WITH VFR OR BRIEFLY MVFR VSBYS WILL PERSIST OVER AND NEAR FAY/RWI WITH MORE ON-AND-OFF RAIN AT RDU AND LITTLE TO NO RAIN AT INT/GSO THE REST OF THIS AFTERNOON. STEADY RAIN WITH MVFR TO IFR VSBYS WILL THEN OVERSPREAD CENTRAL NC SOUTH TO NORTH FROM LATER THIS AFTERNOON THROUGH TONIGHT. WINDS WILL START TO STRENGTHEN 04Z-06Z TONIGHT... RISING TO SUSTAINED 10-15 KTS FREQUENTLY GUSTING TO AROUND 20 KTS. LOOKING BEYOND 18Z WED... CIGS MAY BRIEFLY IMPROVE TO MVFR OR VFR 18Z-03Z... WITH DIMINISHING WINDS LIKELY. ANOTHER FAST-MOVING LOW PRESSURE SYSTEM MOVING IN FROM THE WEST WILL CROSS SRN VA AND NRN NC WED EVENING/NIGHT... BRINGING POTENTIAL IFR CIGS AND LIGHT PRECIP WED NIGHT THROUGH EARLY THU MORNING. VFR CONDITIONS EXPECTED TO RETURN AFTER 15Z THU... LASTING THROUGH SUN... AS HIGH PRESSURE BUILDS IN. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...WSS/BSD LONG TERM...BSD AVIATION...HARTFIELD

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