Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 032009
AFDRAH

FXUS62 KRAH DDHHMM
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
308 PM EST TUE MAR 3 2015

.SYNOPSIS...A WARM FRONT WILL LIFT NORTH THROUGH THE CAROLINAS LATE
TONIGHT AND EARLY WEDNESDAY. A STRONG OLD FRONT WILL APPROACH FROM
THE NORTHWEST WEDNESDAY NIGHT...AND WILL DROP SOUTH THROUGH THE
CAROLINAS ON THURSDAY. ARCTIC HIGH PRESSURE WILL BUILD INTO THE AREA
ON FRIDAY.

&&

.NEAR TERM /TONIGHT/...
AS OF 300 PM TUESDAY...

PATCHES OF LIGHT RAIN/DRIZZLE IN ASSOCIATION WITH SURGE OF WAA
ALOFT...WILL CONTINUE ACROSS THE AREA THROUGH THE REMAINDER OF THE
AFTERNOON AND EARLY EVENING. AFTER 03Z...MODELS INDICATE THE LOW TO
MID-LEVEL WAA WILL WANE...WITH NOTED LOSS IN SATURATION ABOVE 850MB
AFTER 06Z...WHICH WILL LEAD TO DRIZZLE AND THE ENHANCED POTENTIAL
FOR THE DEVELOPMENT OF DENSE FOG OVERNIGHT.

CONFIDENCE REMAINS LOW WRT TEMPERATURES OVERNIGHT...AND THE
WESTERN/INLAND EXTENT OF CAD EROSION  VIA SFC WARM FRONT LIFTING
NORTHWARD INTO CENTRAL NC. GIVEN THE LACK OF A WELL DEFINED UPSTREAM
CYCLONE...ONE WOULD TYPICALLY BE SKEPTICAL OF SIGNIFICANT CAD
EROSION DURING THE OVERNIGHT HOURS AS DEPICTED BY THE GFS WHICH
BLOWS AWAY THE DAMMING REGIME EVEN INTO THE HEART OF THE WEDGE
ACROSS THE NW PIEDMONT. HOWEVER...GIVEN THE POTENTIAL LACK OF
SIGNIFICANT PRECIP TO HELP LOCK IN THE WEDGE...THE GFS SCENARIO
REMAINS PLAUSIBLE. IN CONTRAST...THE HIGHER RESOLUTION NAM...WHICH
TYPICALLY HANDLES CAD EVOLUTION BETTER ACROSS THE CAROLINAS...KEEPS
THE WEDGE IN PLACE ACROSS THE PIEDMONT WITH TEMPS NEARLY STEADY AND
GRADUALLY/MARGINALLY INCREASE BY SUNRISE...PARTICULARLY NORTH OF HWY
64. WILL ERR TOWARDS THE COOLER GUIDANCE AND CAD CLIMATOLOGY...BUT
THERE REMAINS HIGH BUST POTENTIAL THAT TEMPERATURES OVERNIGHT ACROSS
THE EASTERN PIEDMONT...SANDHILLS AND COASTAL PLAIN COULD BE SEVERAL
DEGREES WARMER.

&&

.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 300 PM TUESDAY...

WEDNESDAY:

INSOLATION FROM THE HIGHER SOLAR SUN ANGLE AND BL MIXING VIA STRONG
40-45KT H8 SOUTHWEST FLOW WILL SCOUR OUT ANY LINGERING SHALLOW WEDGE
AIRMASS WITH CENTRAL NC FIRMLY IN THE WARM SECTOR...SOUTH OF THE
COLD FRONT SETTLING INTO THE TN VALLEY. GUIDANCE
OVERCAST LOW CLOUDS WILL BECOME SCT/BKN BY AFTERNOON...WITH BREEZY
SOUTHWESTERLY WINDS DEVELOPING AS THE BL WARMS AND DEEPENS.
SUSTAINED WINDS OF 15 TO 20KTS WITH GUSTS AS HIGH AS 30-35KTS ARE
EXPECTED AS TEMPERATURES RISE INTO THE UPPER 60S NW TO MID 70S
ACROSS THE SOUTH. ONCE THE WEDGE MIXES OUT...FORCING LOOKS LARGELY
ABSENT UNTIL THE ARRIVAL OF THE BACK-DOOR COLD FRONT INTO THE AREA
BETWEEN 06 TO 12Z WITH VERY LITTLE DESTABILIZATION INDICATED...SO
EXPECT MOSTLY DRY CONDITIONS WEDNESDAY AFTERNOON.

WEDNESDAY NIGHT: A STRONG COLD FRONT WILL DROP SOUTH INTO THE AREA
IN BACK-DOOR FASHION DURING THE PREDAWN HOURS. AS A WAVE DEVELOPS
ALONG THE FRONT...ANA-FRONTAL PRECIP WILL SPREAD SOUTH INTO THE
AREA. THERE IS STILL SOME MINOR TIMING ISSUES WITH THE TIMING OF THE
FRONT AND PRECIP INTO THE NORTHERN AREAS...WITH THE NAM BEING A BIT
SLOWER THAN THE GFS AND EC...BUT EXPECT CATEGORICAL POPS BY DAYBREAK
FROM HIGHWAY 64 NORTH...MAKING FOR A MESSY MORNING COMMUTE FOR THE
TRIAD AND TRIANGLE. EXPECT QUITE A SHARP NORTH-SOUTH CONTRAST IN
TEMPERATURES...RANGING FROM LOWER 40S TO LOWER 60S.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...

THURSDAY AND THURSDAY NIGHT: BY 12Z ON THURSDAY...PRECIPIATION
ASSOCIATED WITH THE APPROACHING COLD FRONT WILL HAVE WORKED INTO
NORTHERN SECTIONS OF THE CWA. AT THIS TIME ALL MODELS ARE HINTING AT
THE FORMATION OF A SMALL MESO-LOW FORMING OVER UPSTATE SOUTH
CAROLINA. THIS COULD ACT TO TEMPORARILY INCREASE PRECIPITATION OVER
CENTRAL NC DURING THE DAYTIME HOURS AS FLOW BECOMES MORE
SOUTHEASTERLY AND LOW LEVEL CONVERGENCE INCREASES. THIS FEATURE WILL
QUICKLY ADVECT AWAY BY THURSDAY NIGHT. THE MAIN COLD FRONT HOWEVER
WILL LINGER OVER THE AREA WITH A SOUTHWEST TO NORTHEAST ORIENTATION
AS THE UPPER LEVEL TROUGH REALLY LAGS BACK OVER THE CENTRAL PLAINS
ON THURSDAY AND THE REAL DRIVING FORCE PUSHING IT THROUGH WILL BE A
SURFACE HIGH BACK ACROSS THE TENNESSEE VALLEY. THE EXTREMELY WARM
TEMPERATURES FROM WEDNESDAY WILL QUICKLY COME CRASHING BACK TO
REALITY AS TEMPERATURES DROP THROUGH THE DAY IN THE NORTH AND ONLY
RISE BRIEFLY IN THE SOUTH BEFORE THE FRONT PASSES AND TEMPERATURES
EVENTUALLY DROP BACK BELOW FREEZING THURSDAY NIGHT.

THE COLD AIRMASS WILL BE CHASING THE PRECIPITATION AND AT LEAST IN
SECTION NORTH OF HIGHWAY 64 THERE IS A GOOD CHANCE FOR A WINTRY MIX
OF PRECIPITATION AT THE END OF THE EVENT THURSDAY NIGHT. PRIMARY
TIMING WOULD BE BETWEEN 00Z AND 06Z WITH SLEET THE MOST LIKELY
FROZEN PRECIPITATION TYPE. NORTHEASTERN COUNTIES MAY ALSO SEE A
BRIEF PERIOD OF FREEZING RAIN AT THE INITIAL TRANSITION AROUND 00Z
BUT THEN ALSO CHANGING OVER TO SLEET. FORECAST SOUNDINGS SUPPORT
THIS WITH A VERY WARM NOSE INITIALLY AS TEMPERATURES AT THE SURFACE
DROP BELOW FREEZING AT THE SURFACE. THIS WARM NOSE WILL ERODE RATHER
QUICKLY AND JUST BELOW THAT AN EQUALLY STRONG COLD NOSE
DEVELOPS...SUGGESTING THAT ANY REMAINING PRECIPITATION WILL REFREEZE
PRIOR TO HITTING THE SURFACE. THE GOOD NEWS IS THAT MOST SREF
MEMBERS POINTING TO THE VAST MAJORITY OF PRECIPITATION ENDING PRIOR
TO THE CHANGEOVER TO FREEZING P-TYPES. AS A RESULT NO ICE
ACCUMULATION AND VERY LITTLE SLEET ACCUMULATION IS
EXPECTED...ESPECIALLY WHEN FACTORING IN VERY WARM GROUND
TEMPERATURES FROM WEDNESDAY. MOST PRECIPITATION SHOULD WORK ITS WAY
OUT OF THE AREA AROUND OR JUST AFTER 6Z.

FRIDAY THROUGH SUNDAY NIGHT: THE WEEKEND WILL FEATURE DRIER WEATHER
WITH THE FRONTAL ZONE LOOMING JUST TO OUR SOUTH. A TRANSITORY
SURFACE HIGH WILL CONTROL THE WEATHER PATTERN INITIALLY FOSTERING
COLD TEMPERATURES ON THE EASTERN SIDE OF THE HIGH AND THEN
MODERATING NICELY THROUGH THE WEEKEND. INITIALLY HIGHS IN THE UPPER
30S/LOW 40S ON FRIDAY RISING TO MID TO UPPER 50S BY THE END OF THE
WEEKEND. LOWS SLIGHTLY BELOW FREEZING FRIDAY TO SLIGHTLY ABOVE ON
SUNDAY NIGHT.

MONDAY THROUGH TUESDAY: SOLUTIONS DIVERGE EARLY NEXT WEEK IN REGARDS
TO THE STRENGTH OF THE UPPER LEVEL TROUGH AND A LOW PRESSURE SYSTEM
COMING OUT OF THE GULF OF MEXICO THAT COULD AFFECT OUR AREA EARLY
NEXT WEEK. TEMPERATURES LOOK WARM ENOUGH THAT ANY PRECIPITATION
SHOULD BE LIQUID. HIGHS IN THE UPPER 50S TO LOW 60S. LOWS IN THE MID
TO UPPER 30S.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AS OF 122 PM TUESDAY...

24-HR TAF PERIOD: EXPECT WIDESPREAD MVFR CONDITIONS THIS
AFTERNOON...LOWERING TO IFR IN POCKETS OF LIGHT RAIN AND
DRIZZLE. CEILINGS WILL LOWER TO IFR/LIFR AFTER SUNSET...QUICKLY
FOLLOWED BY VISBYS FALLING TO LIFR/VLIFR WITH WIDESPREAD DENSE FOG
AS A WARM FRONT PROGRESSES NORTHWARD INTO THE COLD AIR DAMMING WEDGE
IN PLACE OVER CENTRAL NC AFTER 05-06Z. CEILINGS ARE EXPECTED TO
IMPROVE FROM SE TO NW AS STRONG SWLY FLOW HELPS TO LIFT AND
SCOUR OUT LINGERING WEDGE AIRMASS IN PLACE...POSSIBLY IMPROVING TO
VFR AT KFAY...KRWI AND KRDU...WHILE MVFR CEILINGS MAY PERSIST
AT KINT AND KGSO. BREEZY SOUTHWEST WINDS ARE EXPECTED TO DEVELOP BY
THE AFTERNOON AS TEMPERATURES START TO WARM INTO THE 60S AND
70S. SUSTAINED WINDS OF 15 TO 20KTS WITH GUSTS AS HIGH AS 30-35 KT
...DEPENDING ON CLOUD COVER/MIXING.


LOOKING AHEAD:  ADVERSE AVIATION CONDITIONS ARE EXPECTED TO RETURN
WEDNESDAY NIGHT AND WILL PERSIST THROUGH THURSDAY IN ASSOC/W A
STRONG COLD FRONTAL PASSAGE AND ATTENDANT ANA-FRONTAL PRECIP BAND
THROUGH THE THE AREA. PRECIPITATION COULD END AS A BRIEF PERIOD
OF SLEET AND FREEZING RAIN THURSDAY AFTERNOON AND EVENING.
VFR CONDITIONS ARE EXPECTED TO RETURN ON FRIDAY...AND SHOULD REMAIN
PREDOMINATELY VFR THROUGH THE WEEKEND.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...CBL/VINCENT
NEAR TERM...CBL
SHORT TERM...CBL
LONG TERM...ELLIS
AVIATION...CBL


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