Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 020832 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 332 AM EST MON MAR 2 2015 .SYNOPSIS...HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTH THIS AFTERNOON THROUGH TONIGHT...IN THE WAKE OF A COLD FRONTAL PASSAGE THIS MORNING. HIGH PRESSURE WILL SHIFT OFFSHORE DURING THE DAY TUESDAY AS A LOW PRESSURE SYSTEM TRACKS NORTHEAST FROM THE CENTRAL PLAINS INTO THE GREAT LAKES. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 130 AM MONDAY... TODAY: A COLD FRONT...APPROACHING THE WESTERN SLOPES OF THE SOUTHERN APPALACHIANS PER 06Z OBSERVATIONS...WILL PROGRESS SOUTHEAST AND THEN SOUTHWARD ACROSS CENTRAL NC LATER THIS MORNING THROUGH EARLY THIS AFTERNOON. DRYING ALOFT ASSOC/W SPEEDY WESTERLY FLOW (30+ KT DOWN TO 950 MB) HAS REDUCED CLOUD COVER ALOFT AND INCREASED RADIATIONAL COOLING AT THE SURFACE OVER CENTRAL NC. DECREASING CLOUD COVER ALOFT...IN THE PRESENCE OF LINGERING SURFACE MOISTURE FROM RECENT RAINFALL AND RESIDUAL SNOWPACK...HAS LED TO THE DEVELOPMENT OF LOW STRATUS AND FOG AREA-WIDE...WITH CEILINGS 100-300 FT AGL AND VISBYS FALLING INTO THE 1/4SM TO 2 SM RANGE AS PF 06Z. IF CURRENT TRENDS PERSIST...A DENSE FOG ADVISORY MAY BE NEEDED SHORTLY FOR MOST IF NOT ALL OF CENTRAL NC. EXPECT CLEARING OF FOG AND LOW STRATUS TO TAKE A WHILE TODAY...NOT UNTIL THE DRIER/COOLER AIRMASS BEHIND THE COLD FRONT ADVECTS SOUTHWARD INTO THE REGION (AFTER NOON)...AND FULL CLEARING MAY NOT BE ACHIEVED IN ALL LOCATIONS BY SUNSET. EXPECT HIGHS IN THE LOW TO MID 50S. TONIGHT: THOUGH DECREASED CLOUD COVER SHOULD BE PRESENT FOR A PERIOD THIS EVENING...LOW CEILINGS WILL RE-DEVELOP AFTER MIDNIGHT IN ASSOC/W SOUTHERLY RETURN FLOW /WARM ADVECTION/ AS THE LOW-LEVEL RIDGE SHIFTS QUICKLY OFFSHORE. IN ADDITION TO STRENGTHENING WARM ADVECTION...DPVA IN THE FORM OF FAST-MOVING/SMALL AMPLITUDE SHORTWAVE ENERGY IS EXPECTED TO BE PRESENT BETWEEN 06-12Z TUE... AND LIGHT PRECIP WILL BE POSSIBLE IN THE WESTERN PIEDMONT AND WESTERN PORTIONS OF THE SANDHILLS BY SUNRISE TUE. DUE TO THE PROGRESSIVE NATURE OF THE HIGH BUILDING INTO THE REGION LATER TODAY...THE AIRMASS IN PLACE TUE MORNING WILL BE LESS CAPABLE OF SUPPORTING MIXED PTYPE THAN IN THE PREVIOUS EVENT. NEVERTHELESS...A NUISANCE PERIOD OF LIGHT PL/FZRA CANNOT BE RULED OUT ACROSS ALONG AND WEST OF THE HWY 1 CORRIDOR AROUND SUNRISE TUE MORNING. GIVEN ABOVE NORMAL UNCERTAINTY WITH REGARD TO THE QUALITY OF THE ANTECEDENT AIRMASS AND EVOLUTION OF PRECIPITATION TUE MORNING...THE FORECAST WILL SIMPLE REFLECT A CHANCE OF LIGHT RAIN BETWEEN MIDNIGHT-SUNRISE FROM THE TRIANGLE WESTWARD. EXPECT LOWS IN THE LOWER TO MID 30S. -VINCENT && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... AS OF 200 AM MONDAY... TUE: A PRONOUNCED COLD AIR DAMMING WEDGE WILL BE IN PLACE TUE...WITH PERIODS OF DRIZZLE OR LIGHT RAIN POSSIBLE THROUGHOUT THE DAY IN ASSOC/W MODEST (ALBEIT STEADY) WARM ADVECTION...THOUGH LITTLE IF ANY UPPER LEVEL FORCING IS ANTICIPATED AT THIS TIME. EXPECT HIGHS WELL BELOW NORMAL IN THE LOWER/MID 30S (NW) TO MID/UPPER 30S ELSEWHERE. TEMPS COULD VARY A GOOD 4-7F FROM THIS FORECAST IF LIGHT PRECIP (AND ASSOC EVAP COOLING) DO NOT OCCUR AS ANTICIPATED. TUE NIGHT: LOWS WED MORNING WILL LIKELY OCCUR AT MIDNIGHT IN MOST AREAS. A WARM FRONT IS EXPECTED TO LIFT NORTHWARD TOWARD CENTRAL NC TUE NIGHT...HOWEVER...GIVEN AN UNAMPLIFIED PATTERN...RELATIVELY WEAK MSLP/HEIGHT GRADIENT AND THE LACK OF A WELL DEFINED UPSTREAM CYCLONE...IT SHOULD BE DIFFICULT FOR THE WARM FRONT TO MAKE MUCH PROGRESS THROUGH THE CAD WEDGE IN PLACE ACROSS CENTRAL NC. SLOW/STEADY PROGRESS INTO THE SANDHILLS AND COASTAL PLAIN SHOULD RESULT IN RISING TEMPS AFTER MIDNIGHT IN MOST LOCATIONS...THOUGH PERHAPS REMAINING STEADY IN THE MID/UPPER 30S ACROSS THE N/NW PIEDMONT WITH ONLY A SLIGHT RISE TO NEAR 40F IN THE TRIANGLE BY SUNRISE WED. SOUTHERN PORTIONS OF THE SANDHILLS AND COASTAL PLAIN ARE MOST LIKELY TO SEE TEMPERATURES RISING INTO THE MID/UPPER 40S AND PERHAPS LOWER 50S BY SUNRISE WED. -VINCENT && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 323 AM MONDAY... THE LATEST MODEL RUNS AND CURRENT TRENDS IN THE MODELS SUGGEST THAT THE NEXT ARCTIC FRONT WILL BE DELAYED SOMEWHAT FROM PREVIOUS FORECASTS. THIS DOES HAVE IMPLICATIONS ON THE CURRENT FORECAST FOR WEDNESDAY INTO FRIDAY. WEDNESDAY IS STILL EXPECTED TO BE THE WARMEST DAY WITH A BROAD SOUTHWEST FLOW OUT AHEAD OF THE FRONT THAT WILL LIKELY BECOME STALLED ALONG THE WESTERN SLOPES OF THE MOUNTAINS LATE WEDNESDAY INTO WEDNESDAY NIGHT. AT LEAST PARTIAL SUNSHINE IN THE SW FLOW IN THE WARM SECTOR WOULD YIELD HIGHS IN THE UPPER 60S TO MID 70S NW TO SOUTH ON WEDNESDAY. FOR WEDNESDAY NIGHT AND THURSDAY... THE ARCTIC FRONT IS FORECAST TO SLIP THROUGH CENTRAL NORTH CAROLINA LATE WEDNESDAY NIGHT AND THURSDAY FROM THE NORTH. THE PARENT HIGH IS PROGGED TO BE STRONG (1035 MB OR SO)... BUT OVER THE UPPER MIDWEST... THUS THE COLD AIR SHOULD BE SHALLOW AND INITIALLY BLOCKED BY THE CENTRAL APPALACHIANS. IT WOULD NOT BE UNTIL THURSDAY (AND POSSIBLY DELAYED EVEN MORE) BEFORE A POTENTIAL LINGERING FRONTAL WAVE WOULD FOCUS RAIN BEHIND THE FRONT... WHICH COULD POSSIBLY CHANGE TO A WINTERY MIXTURE ACROSS THE NORTHWEST OR NORTHERN PIEDMONT. REGARDLESS... WHAT IS DIFFERENT FROM THIS WINTER P-TYPE POTENTIAL IS AT LEAST TWO FOLD... 1) THE CHANGE OVER (IF IT OCCURS AT ALL - WOULD BE AFTER RAIN FALLS FOR A GOOD LONG PERIOD OF TIME LATE WEDNESDAY NIGHT AND THURSDAY... 2) THE TEMPERATURES WOULD START IN THE 50S/60S WEDNESDAY NIGHT... BEFORE FALLING INTO THE 30S/40S THURSDAY... AND 3) THE WARMTH PRECEDING THE POTENTIAL EVENT (HIGHS IN THE 70S WEDNESDAY)... WILL BE ANYTHING BUT WHAT WE HAVE SEEN LEADING UP TO THE RECENT (COLD) WINTER WEATHER EVENTS. THEREFORE... THIS SYSTEM APPEARS THAT IT WOULD LIKELY NOT POSE A SIGNIFICANT THREAT AT THE CURRENT TIME. SENSIBLE WEATHER AS IT CURRENTLY LOOKS... WARM AND PARTLY SUNNY WEDNESDAY. HIGHS GENERALLY 70-77. BECOMING CLOUDY EAST WITH RAIN LIKELY WEST WEDNESDAY NIGHT. LOWS 50S/60S... FALLING INTO THE 40S NORTHERN PIEDMONT TOWARD 12Z/THU. THURSDAY... RAIN LIKELY. TEMPERATURES FALLING INTO THE MID 30S TO MID 40S. RAIN ENDING POSSIBLY BRIEFLY AS A WINTERY MIXTURE IN THE NORTH AND NORTHEAST THURSDAY NIGHT. LOWS IN THE 20S. FRIDAY THROUGH SUNDAY... PARTLY CLOUDY. COLDER. LOWS IN THE 20S. HIGHS IN THE 30S TO LOWER 40S FRIDAY... AND IN THE 40S SAT... THEN 50S SUNDAY. THIS IS STILL A LOW CONFIDENCE FORECAST FOR PRECIPIATION TYPE THURSDAY INTO THURSDAY NIGHT. IF THE ARCTIC FRONT CAN PUSH THROUGH EARLY THURSDAY... AND A MORE SIGNIFICANT WAVE CAN DEVELOP ALONG THE FRONT AS THE COLD AIR IS PUSHING IN FROM THE NORTH... THEN MORE IN THE WAY OF SNOW/SLEET MAY FALL THAN IS CURRENTLY THOUGHT... MAINLY ACROSS THE NORTHERN PIEDMONT. HOWEVER... CONFIDENCE IS LOWERED IN ACCUMULATIONS THAT WOULD BE ANTICIPATED DUE TO TIMING (MAINLY AFTERNOON)... THE EXPECTED WARMTH AND RAIN PRECEDING THE FRONT... AND THE WARMING SOIL TEMPS. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 200 AM MONDAY... 24-HR TAF PERIOD: LIFR/VLIFR CONDITIONS WITH DENSE FOG AND/OR LOW CEILINGS WILL PREVAIL THROUGH ~15Z...IMPROVING TO IFR/MVFR BY 18Z AND MVFR TO POSSIBLY VFR BY 21-00Z AS DRY HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTH. IMPROVEMENT WILL BE SHORT-LIVED... HOWEVER...WITH MVFR/IFR CEILINGS RETURNING BETWEEN MIDNIGHT AND SUNRISE TUE MORNING AS THE SFC HIGH MOVES QUICKLY OFFSHORE... SOUTHERLY RETURN FLOW DEVELOPS IN THE LOWER LEVELS...AND AN UPPER LEVEL DISTURBANCE APPROACHES FROM THE WEST. LOOKING AHEAD: ADVERSE AVIATION CONDITIONS (IFR/LIFR CEILINGS AND RAIN) ASSOC/W A PRONOUNCED COLD AIR DAMMING WEDGE WILL PREVAIL TUE... WITH SOME IMPROVEMENT IN CEILINGS POSSIBLE AT SOUTHERN TERMINALS LATE TUE NIGHT AS A WARM FRONT LIFTS NORTHWARD THROUGH THE CAROLINAS. ADVERSE AVIATION CONDITIONS ARE LIKELY TO PREVAIL THE REMAINDER OF THE WEEK. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR NCZ007>011-021>028-038>043-073>078-083>086-088- 089. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...VINCENT LONG TERM...BADGETT AVIATION...VINCENT

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