Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 271531 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1030 AM EST FRI FEB 27 2015 .SYNOPSIS... COLD HIGH PRESSURE OVER THE CENTRAL PLAINS WILL BUILD INTO THE MID ATLANTIC TODAY THROUGH SATURDAY. && .NEAR TERM /THROUGH SATURDAY NIGHT/... AS OF 1030 AM FRIDAY... TEMPERATURES HAVE RISEN ABOVE FREEZING ACROSS MOST OF OUR FORECAST AREA...WITH THE ONLY EXCEPTION BEING ACROSS OUR WESTERN ZONES WHERE SOME STRATUS IS DELAYING WARMING. EVEN IN THAT AREA...THERE ARE ONLY A FEW SITES STILL REPORTING 31 OR 32 DEGREES...THUS WE LET THE WSW FOR BLACK ICE EXPIRE ON TIME AT 10 AM. LATEST VIS SATELLITE SHOWS STATUS ACROSS OUR WESTERN ZONES AND MAINLY CLEAR SKIES ACROSS OUR EASTERN ZONES. WHERE SKIES ARE CLEAR...THE TEMP QUICKLY CLIMBED AFTER SUNRISE...AND HAS ALREADY REACHED THE LOWER 40S ACROSS OUR SE ZONES. AS SUCH...FOR OUR NEXT PRODUCT UPDATE WE`LL BUMP UP TEMPS A FEW DEGREES FOR THIS AFTERNOON ACROSS OUR SE ZONES...AND PERHAPS LOWER A DEGREE OR SO ACROSS OUR WESTERN ZONES DEPENDING ON THE EVOLUTION OF THE AFOREMENTIONED STRATUS. OTHERWISE...THE REST OF THE FORECAST IS ON TRACK AND THE PREV NEAR-TERM DISC PROVIDED BELOW FOR REFERENCE. PREV NEAR TERM DISC AS OF 300 AM...FAST SW FLOW ALOFT WILL MAINTAIN A DECK OF HIGH LEVEL CLOUDS OVER THE REGION WHILE THE APPROACH OF A S/W CROSSING THE LOWER OH VALLEY WILL CAUSE PERIODS OF MID CLOUDS AS WELL. LIFT APPEARS TO BE ENOUGH TO GENERATE CLOUDS BUT NOT ENOUGH TO GENERATE PRECIPITATION THOUGH COULD SEE A POCKET OF DRIZZLE OR SNOW FLURRIES THIS AFTERNOON WHEN THE TAIL END OF THE S/W CROSSES OUR REGION. LOW LEVEL THICKNESSES THIS AFTERNOON AVERAGE 50-60M BELOW AVERAGE...SUPPORTIVE OF MAX TEMPS WELL BELOW NORMAL FOR LATE FEBRUARY. FAVOR MAX TEMPS ON THE COOL SIDE OF MOS GUIDANCE. EXPECT MAX TEMPS IN THE UPPER 30S TO AROUND 40 NORTH TO THE LOW-MID 40S SOUTH. THE AFOREMENTIONED S/W WILL USHER A SFC COLD FRONT ACROSS CENTRAL NC LATE THIS AFTERNOON/EARLY THIS EVENING. THE AIR MASS BEHIND THIS SFC FEATURE WILL BE NOTICEABLY DRIER AND COOLER. EXPECT SOME MINOR DECREASE IN CLOUDINESS OVERNIGHT BUT NOT EXPECTING TOTALLY CLEAR SKIES. THICKNESSES IN THE 1260-1265M RANGE HISTORICALLY SUGGEST MIN TEMPS CLOSE TO 20 DEGREES. FAVOR THE COOLER MAV GUIDANCE VERSUS THE WARMER MET. SATURDAY...1040+MB HIGH CENTERED OVER SOUTHERN NEW ENGLAND WILL NOSE SOUTHWARD INTO THE CAROLINAS. THIS DRY AIR RIDGE AND ACCOMPANYING 850MB THERMAL TROUGH WILL RESULT IN ANOTHER DAY OF WELL BELOW NORMAL TEMPS. FAVOR THE COOLER MAV GUIDANCE THOUGH IF PEEKS OF SUN MORE PREVALENT THEN CURRENT THINKING...AFTERNOON TEMPS COULD END UP BEING 3-4 DEGREES WARMER THAN FORECAST. THE NEXT LOW PRESSURE SYSTEM WILL BE DEVELOPING/APPROACHING FROM THE WEST-SW SATURDAY NIGHT. MEANWHILE DRY AIR SFC RIDGE WILL BEGIN TO SHIFT OFFSHORE BUT STILL MAINTAIN A PRESENCE ACROSS OUR REGION. MOS GUIDANCE...MAINLY THE MAV...APPEARS TOO COLD CONSIDERING THE INCREASING/THICKENING CLOUD COVERAGE. WHILE ISENTROPIC UPGLIDE WILL BE ON THE INCREASE TOWARD DAYBREAK SUNDAY...LIFT APPEARS TOO WEAK TO GENERATE PRECIPITATION. THUS WILL MAINTAIN A DRY FORECAST. MIN TEMPS UPPER TEENS TO AROUND 20 NE TO THE MID 20S FAR SOUTH AND WEST. && .SHORT TERM /SUNDAY THROUGH MONDAY/... AS OF 300 AM FRIDAY... SURFACE HIGH PRESSURE OVER THE AREA SUNDAY MORNING WILL QUICKLY SHIFT OFFSHORE BY SUNDAY AFTERNOON AS A QUICK MOVING S/W DISTURBANCE MOVES EASTWARD FROM THE NORTHERN PLAINS INTO THE GREAT LAKES REGION... WITH AND ASSOCIATED COLD FRONT APPROACHING THE AREA FROM THE NORTHWEST. IN RESPONSE TO THE APPROACHING SYSTEM... A MOIST SOUTH/SOUTHWESTERLY LOW LEVEL FLOW ATOP A DEPOSITED COLD SURFACE AIRMASS WILL INCREASE THROUGHOUT THE DAY ON SUNDAY... WITH PRECIP POSSIBLY DEVELOPING ACROSS WESTERN PORTIONS OF THE CWA. THE LATEST NAM CONTINUES TO BE AN OUTLIER IN BRING PRECIP IN DURING THE EARLY MORNING HOURS ON SUNDAY. IF THIS INDEED OCCURRED THEN WE MAY HAVE SOME P-TYPE ISSUES (GENERALLY SLEET AND/OR FREEZING RAIN) ACROSS MAINLY WESTERN PORTIONS OF THE AREA. HOWEVER... WITH BOTH THE GFS AND ECMWF REMAINING DRY UNTIL THE AFTERNOON ACROSS THE WESTERN PORTION OF THE AREA... WILL ONLY SHOW A CHANCE OF RAIN ACROSS THE WESTERN PIEDMONT DURING THE AFTERNOON HOURS (CHILLY RAIN THOUGH). NONETHELESS... WITH THE SURFACE RIDGE AXIS EXTENDING BACK INTO THE AREA AFTER IT MOVES OFFSHORE ALONG WITH SOME PRECIP POSSIBLE ACROSS AT LEAST WESTERN PORTIONS OF THE AREA BY AFTERNOON EXPECT SKIES WILL BE CLOUDY WITH HIGHS EXPECTED TO BE WELL BELOW NORMAL AGAIN. FOR NOW WILL ONLY LOWER PREVIOUS HIGH TEMPS BY A COUPLE OF DEGREES. THIS YIELDS HIGHS RANGING FROM THE UPPER 30S NW TO THE MID TO UPPER 40S SE. THE SURFACE COLD FRONT WILL APPROACH AND MOVE THROUGH CENTRAL NC ON SUNDAY NIGHT INTO MONDAY... HELPING TO SOUR OUT ANY COLD AIR DAMMING AIRMASS THAT IS ABLE TO DEVELOP. HOWEVER... AHEAD OF THE FRONT EXPECT WE WILL SEE POCKETS OF LIGHT RAIN AND DRIZZLE TO DEVELOP ON SUNDAY NIGHT... WITH POSSIBLY A BAND OF LIGHT SHOWERS ON MONDAY ALONG AND AHEAD OF THE COLD FRONT. LOWS AND HIGHS WILL BE TRICKY AND DEPEND ON THE EXTENT OF THE CAD AND HOW QUICKLY THE FRONT MOVES THROUGH. FOR NOW WILL TREND TEMPS COOLER. LOW TEMPS MONDAY MORNING RANGING FROM THE MID 30S NORTH/NORTHWEST TO THE LOWER 40S SE. HIGHS MONDAY IN THE LOWER TO MID 50S (WITH A HIGH BUST POTENTIAL... ESPECIALLY IF THERE IS A LINGERING CAD BOUNDARY ACROSS THE AREA). && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... AS OF 320 AM FRIDAY... STRONG SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA FROM THE NORTHWEST ON MONDAY NIGHT INTO TUESDAY... WITH THE AFOREMENTIONED SURFACE FRONT SETTLING TO THE SOUTH OF THE AREA. MEANWHILE... MID LEVEL RIDING WILL BUILD ACROSS THE AREA AS THE MID LEVEL FLOW ACROSS THE CONUS BECOMES MORE AMPLIFIED. THE LATEST GFS AND ECMWF CONTINUE TO DISAGREE WITH HOW QUICKLY WE WILL SEE A MOISTENING SOUTHERLY RETURN FLOW DEVELOP ACROSS THE AREA... POSSIBLY RESULTING IN THE DEVELOPMENT OF ANOTHER CAD AIRMASS. GIVEN WPC CONTINUES TO TREND TOWARDS THE WETTER SIDE OF THE GUIDANCE... WILL CONTINUE TO KEEP SKIES CLOUDY... WITH A CONTINUED CHANCES FOR PRECIP (WHICH IS MORE IN LINE WITH THE LATEST GFS). GIVEN THIS WILL KEEP TEMPS ON THE COOLER SIDE OF GUIDANCE AND GO WITH HIGH TEMPS ON TUESDAY RANDING FROM THE LOWER TO MID 40S NW TO THE LOWER TO MID 50S SE... WITH LOW TEMPS TUESDAY MORNING IN THE MID 30S NORTH TO AROUND 40 SOUTH. AS THE NEXT SURFACE FRONT BEGINS TO APPROACH THE REGION FROM THE WEST... EXPECT ANY LINGERING CAD AIRMASS TO BEGIN TO ERODE. THUS... LOW TEMPS ON TUESDAY NIGHT/WEDNESDAY MORNING COULD OCCUR EARLY IN THE NIGHT... WITH POSSIBLE RISING TEMPS OVERNIGHT. WILL NOT GET THAT DETAILED IN THE GRIDDED FORECAST AT THAT TIME GIVEN UNCERTAINTY OVER IF WE WILL SEE A CAD AIRMASS EVEN DEVELOP. LOWS TUESDAY NIGHT/WEDNESDAY MORNING IN THE LOWER 40S NW TO THE LOWER 50S SE. THE AFOREMENTIONED NEXT SURFACE COLD FRONT WILL SLOWLY MOVE ACROSS THE REGION WEDNESDAY INTO THURSDAY MORNING AS THE SURFACE FRONT BECOMES MORE PARALLE TO THE MID LEVEL FLOW. GIVEN THE SLOW MOVING FRONT WITH ALONG WITH A GOOD TAP OF MOISTURE FROM THE GULF OF MEXICO WE COULD SEE DECENT RAINFALL TOTALS WEDNESDAY (MAINLY NORTHWEST PIEDMONT WEDNESDAY DURING THE DAY... AT THIS TIME) INTO THURSDAY. IN ADDITION... TEMPS AHEAD OF THE FRONT ARE EXPECTED TO REBOUND QUITE NICELY (WITH THE CAD AIRMASS EXPECTED TO ERODE PRIOR TO PASSAGE OF THE COLD FRONT EVEN IN THE NW) TO AROUND 60/LOWER 60S NW TO THE LOWER TO MAYBE EVEN MID 70S SE. HIGHS AND LOWS ON THURSDAY WILL DEPEND ON HOW QUICKLY THE FRONT MOVES THROUGH THE REGION. FOR NOW WILL GO WITH LOWS THURSDAY MORNING IN THE MID 40S TO LOWER 50S... WITH HIGHS IN THE 50S TO LOWER 60S. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... AS OF 708 AM FRIDAY... MAIN AVIATION HAZARD THROUGH MID MORNING WILL BE IFR/LIFR VISIBILITY DUE TO FREEZING FOG. THE PROBABILITY OF LIFR VISIBILITY IS HIGHEST IN THE COASTAL PLAIN AND THE NORTHERN PIEDMONT INCLUDING IN VICINITY OF KRWI...KINT...KGSO...AND KRDU. VISIBILITIES WILL IMPROVE BETWEEN 12Z-14Z. OTHERWISE...EXPECT A DECK OF HIGH END MVFR/LOW END VFR CEILINGS AROUND MID DAY THROUGH AFTERNOON AS AN UPPER LEVEL DISTURBANCE SKIRTS ACROSS THE REGION. SFC WINDS WILL GO FROM LIGHT AND VARIABLE EARLY TO NORTHERLY NEAR 10KTS BY LATE MORNING-EARLY AFTERNOON. MOISTURE TRAPPED BELOW A DEVELOPING SUBSIDENCE INVERSION MAY CAUSE A DECK OF STRATUS TO MOVE ACROSS CENTRAL NC OVERNIGHT...RESULTING IN A PERIOD OF MVFR/IFR CEILINGS. OTHERWISE VFR CONDITIONS WILL RETURN SATURDAY AND RETURN SATURDAY NIGHT AS HIGH PRESSURE BECOMES ESTABLISHED ACROSS THE AREA. AS THE HIGH SHIFTS EAST SUNDAY...SOUTHERLY RETURN FLOW WILL ADVECT A WARMER MOIST AIR MASS INTO OUR AREA...RESULTING IN AN INCREASED PROBABILITY OF MVFR CEILINGS ALONG WITH PATCHES OF RAIN. THE ADVERSE AVIATION WEATHER CONDITIONS ARE EXPECTED TO PERSIST INTO TUESDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY IN EFFECT THROUGH 10 AM EST THIS MORNING FOR NCZ007>011-021>028-038>043- 073>078-083>086-088-089. && $$ SYNOPSIS...BADGETT NEAR TERM...WSS SHORT TERM...BSD LONG TERM...BSD AVIATION...WSS

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