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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