Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 270222
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1022 PM EDT THU MAR 26 2015

.SYNOPSIS...A COLD FRONT WILL TRACK SOUTHEAST THROUGH CENTRAL NORTH
CAROLINA LATE TONIGHT. THE COLD FRONT WILL BRIEFLY STALL OFFSHORE
THE CAROLINA COAST ON FRIDAY AS A POTENT UPPER LEVEL DISTURBANCE
APPROACHES FROM THE WEST.

&&

.NEAR TERM /TONIGHT/...
AS OF 1015 PM THURSDAY...

THE SURFACE COLD FRONT MOVING THROUGH THE MOUNTAINS IS BEING
PRECEDED BY A NARROW LINE OF SHOWERS...THOUGH THE BETTER COVERAGE IS
NORTH OF THE NC/VA BORDER NEAR BLACKSBURG.  MODELS STILL SHOW A
RELATIVELY SLOW PROGRESSION OF THE FRONT THROUGH THE CWA
TONIGHT...ONLY REACHING THE SANDHILLS AND SOUTHERN COASTAL PLAIN BY
SUNRISE... WHILE THE UPPER TROUGH AXIS LAGS WELL TO THE WEST.  THERE
 HAVE BEEN NO SHOWERS OVER CENTRAL NC THIS EVENING...MOSTLY OWING TO
A GOOD CAP AT 700MB AND NO INSTABILITY.   SOME COOLING AT 700MB IS
EXPECTED OVER THE NEXT FEW HOURS...AND ALONG WITH A DISTURBANCE
UPSTREAM OVER GA NOTED ON WATER VAPOR...SHOULD HELP TO ENHANCE THE
COVERAGE OF SHOWERS  AS THE FRONT MOVES THROUGH THE AREA.  THE MOST
RECENT HRRR SHOWS THE CURRENT PREFRONTAL SHOWERS MAKING LITTLE
PROGRESS INTO THE PIEDMONT...WITH SOME REDEVELOPMENT ALONG THE FRONT
AFTER 06Z.  EVEN THEN THE COVERAGE IS NOT THAT GREAT...SO WILL BE
REDUCING POPS A BIT OVERNIGHT...EXPECTING THE BEST COVERAGE TO COME
POST-FRONTAL MORE TOWARD 12Z AS THE UPPER TROUGH NEARS THE AREA AND
PW RISES TO 1 TO 1.25 INCHES.  MOST GUIDANCE IS ALSO TOUCH WARMER
WITH TEMPS THROUGH 12Z...LIKELY DUE TO THE COOLER AIR BEING SLOWED
BY THE MOUNTAINS.  USING SOME OF THE MOST RECENT HI-RES GUIDANCE
YIELDS UPPER 40S NORTH TO UPPER 50S SOUTH.

 &&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 315 PM THURSDAY...

FRIDAY...WIDESPREAD SHOWERS IN THE MORNING WILL DIMINISH BY EARLY
AFTERNOON...COINCIDING WITH THE PASSAGE OF THE 850-700MB TROUGHS.
STRONG LOW LEVEL NLY FLOW WILL ADVECT COLDER AIR INTO THE REGION
THROUGHOUT THE DAY. TEMPS WILL CONTINUE TO FALL THROUGH THE MORNING
AND EARLY AFTERNOON HOURS...POSSIBLY STABILIZING BY MID AFTERNOON.

FRIDAY NIGHT...UPPER LEVEL TROUGH CROSSES THE REGION...ACCOMPANIED
BY A FEW SHOWERS. MODEL CROSS SECTIONS OF LIFT/MOISTURE DO DEPICT
ENOUGH SATURATION IN THE ICE NUCLEATION REGION TO CAUSE SNOW TO FORM
ALOFT. HOWEVER THE LOWER LAYERS ARE DRYING OUT TO SUCH A DEGREE THAT
ANY SNOW THAT FALLS WILL LIKELY MELT AND/OR EVAPORATE BEFORE
REACHING THE SURFACE. THUS WILL CONFINE MENTION OF PRECIP TO RAIN
SHOWERS FOR NOW. LOWER LAYERS OF THE ATMOSPHERE REMAIN WELL MIXED
THROUGH FRIDAY NIGHT. THIS MIXING ALONG WITH VARIABLY CLOUDY SKIES
MAY AID TO KEEP TEMPS UP A BIT IN SPITE OF THE COLD AIR ADVECTION.
SOME MOS GUIDANCE HAS MIN TEMPS BY EARLY SATURDAY IN THE UPPER 20S
TO AROUND 30 OVER THE PIEDMONT. THIS SEEMS A LITTLE EXTREME SO AM
MORE IN FAVOR OF MIN TEMPS NEAR FREEZING NW TO THE MID-UPPER 30S
ELSEWHERE. IF SKIES ARE ABLE TO CLEAR AND SFC WINDS DECOUPLE...COULD
SEE AN ARGUMENT FOR MIN TEMPS IN THE UPPER 20S-LOWER 30S.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
AS OF 245 PM THURSDAY...

THIS WEEKEND: THE MAIN WEATHER STORY THIS WEEKEND WILL BE THE COLD
TEMPERATURES... IN THE WAKE OF THE TROUGH THAT IS PROGGED TO PUSH
ACROSS OUR AREA EARLY IN THE PERIOD. COLD HIGH PRESSURE WILL BUILD
ACROSS OUR AREA FROM THE NW OVER THE WEEKEND...BRINGING AN AIRMASS
THAT FEATURES LOW LEVEL THICKNESSES ABOUT 60M BELOW NORMAL. DESPITE
MAINLY CLEAR SKIES AND AMPLE SUNSHINE DURING THE DAY...HIGHS
SATURDAY WILL ONLY CLIMB TO THE UPPER 40S NORTH TO LOWER 50S SOUTH.
SATURDAY NIGHT...LOOK FOR SUB-FREEZING LOW TEMPS ACROSS ALL OF
CENTRAL NC...THANKS TO THE COMBINATION OF THE AFOREMENTIONED
AIRMASS...MAINLY CLEAR SKIES AND CALM WIND UNDER THE HIGH PRESSURE
CENTER. RIGHT NOW WE`RE SHOWING LOWS RANGING FROM THE MID 20S ACROSS
THE TRIAD TO AROUND 30 ACROSS THE SOUTHERN COASTAL PLAIN...BUT WITH
THE HIGH CENTERED OVER US BY 12Z SUN...THOSE TEMPS MAY END UP EVEN
COLDER IN SPOTS. WE`LL BEGIN TO SEE SOME MODERATION ON SUNDAY AS THE
HIGH CENTER SHIFTS TO OUR SOUTHEAST...BUT STILL ABOUT 10 DEG BELOW
NORMAL...HIGHS IN THE MID 50S.

SUNDAY NIGHT THROUGH THURSDAY: A SHORT WAVE IS PROGGED TO QUICKLY
MOVE ACROSS OUR AREA SUNDAY NIGHT INTO MONDAY MORNING...BUT ASIDE
FROM A FEW PASSING SPRINKLES...RIGHT NOW IT APPEARS THAT FEATURE
WILL MOVE ACROSS MOSTLY DRY. HIGH PRESSURE WILL BRIEFLY BUILD ACROSS
OUR AREA LATE MONDAY INTO TUESDAY...PRIOR TO THE NEXT COLD FRONT
THAT IS PROGGED TO CROSS THE CAROLINAS ON WEDNESDAY. RIGHT NOW THAT
FRONT APPEARS TO COME THROUGH DRY AS WELL...GIVEN THAT THE DEEPER
MOISTURE AHEAD OF IT IS FORECAST TO REMAIN MOSTLY TO OUR SOUTH. RAIN
CHANCES MAY INCREASE ON THURSDAY AS THE FRONT LIFTS BACK TO OUR
NORTH AS A WARM FRONT AHEAD OF A FAST-MOVING SOUTHERN STREAM SHORT
WAVE. AS FOR TEMPERATURES DURING THIS TIME....LOOK FOR A GRADUAL
WARMUP...WITH READINGS CLOSER TO NORMAL THANKS TO THE PATTERN
DEAMPLIFYING AND BECOMING MORE ZONAL WITH TIME ACROSS OUR AREA.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 1020 PM THURSDAY...

TAFS HAVE BEEN AMMENDED TO REFLECT A SLOWER PROGRESSION OF A FRONTAL
PASSAGE AND SUBSEQUENT WEATHER CONDITIONS OUTLINED BELOW.

VFR CONDITIONS WILL PREVAIL IN ADVANCE OF A COLD FRONT THAT WILL
MOVE SOUTHEAST ACROSS CENTRAL NC TONIGHT...WITH TIMING THROUGH INT
AND GSO BETWEEN 05-08Z; RDU AND RWI BETWEEN 08-10Z; AND FAY BETWEEN
10-13Z. THE PASSAGE OF THE FRONT WILL RESULT IN A SHARP WIND SHIFT
FROM SSW TO NW AND BE ACCOMPANIED BY A NARROW BAND OF LOW-TOPPED
SHOWERS (AND POSSIBLY AN ISOLATED THUNDERSTORM) WITH GUSTY NW WINDS.
POST-FRONTAL RAIN AND MVFR-IFR CONDITIONS WILL FOLLOW THE FRONT...
THOUGH IT MAY TAKE SEVERAL HOURS BEHIND THE FRONT FOR ANY SUCH SUB-
VFR CONDITIONS TO BECOME PREVAILING CONDITIONS. WINDS WILL THEN
GRADUALLY VEER TO A MORE NORTHERLY TO NORTHEASTERLY COMPONENT
BETWEEN 12-18Z...AT WHICH TIME BLUSTERY SUSTAINED WINDS AND GUSTS
WILL BE PROBABLE - HIGHEST AT EASTERN TAF SITES. RAIN WILL END FROM
WEST TO EAST AFTER 18Z FRI...WITH AN ACCOMPANYING IMPROVEMENT IN
FLIGHT CATEGORY TO MVFR...OR LIFTING AND SCATTERING TO VFR...BY LATE
AFTERNOON - SLOWEST AT EASTERN TERMINALS.

OUTLOOK: A BRIEF PERIOD OF SUB-VFR CONDITIONS MAY REDEVELOP WITH THE
PASSAGE OF AN UPPER LEVEL DISTURBANCE FRI NIGHT...PARTICULARLY AT
EASTERN TAF SITES. OTHERWISE...THERE WILL BE A THREAT OF MVFR
CEILINGS WITH THE PASSAGE OF ANOTHER COLD FRONT SUN NIGHT.

&&

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

&&

$$

SYNOPSIS...WSS
NEAR TERM...WSS/22
SHORT TERM...WSS
LONG TERM...RAH
AVIATION...RAH



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