Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 301039
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
640 AM EDT MON MAR 30 2015

.SYNOPSIS...A COLD FRONT WILL MOVE THROUGH THE REGION TODAY. HIGH
PRESSURE WILL BRIEFLY MOVE ACROSS THE REGION ON TUESDAY...AND WILL
BE FOLLOWED BY ANOTHER COLD FRONT THAT WILL MOVE ACROSS THE
CAROLINAS TUESDAY NIGHT. HIGH PRESSURE WILL BUILD BACK OVER THE
REGION FOR WEDNESDAY.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 315 AM MONDAY...

LATEST SFC ANALYSIS SHOWS A COLD FRONT CROSSING THE MIDWEST AND MID
MISSISSIPPI REGIONS. NATIONAL RADAR COMPOSITE SHOWS A PREFRONTAL
BAND OF SHOWERS EXTENDING FROM CENTRAL NY...SOUTHWEST TO THE TN
VALLEY WHERE A FEW TSTMS ARE EMBEDDED WITHIN THIS ACTIVITY. LATEST
HRRR SEEMS TO HAVE A GOOD HANDLE ON THIS ACTIVITY...AND SHOWS RAIN
SHOWERS MOVING EAST AND REACHING OUR TRIAD ZONES BY 8 AM OR SO...THE
TRIANGLE REGION BY 10 AM...AND THE I-95 CORRIDOR AROUND 11 AM.  IT
WILL BE FAIRLY SHORT-LIVED...THANKS TO THE PROGRESSIVE NATURE OF THE
ASSOC MID-LEVEL SHORT WAVE...SO LOOK FOR THE RAIN TO END ACROSS THE
TRIAD BY NOON...TRIANGLE BY 2 PM...AND THE I-95 CORRIDOR BY 4 PM.
THE ACTUAL COLD FRONT WILL LAG BEHIND BY A FEW HOURS...MOVING ACROSS
CENTRAL NC DURING THE MID AFTERNOON HOURS. IN TERMS OF SHOWER
INTENSITY...SINCE THE LOW LEVEL AIRMASS WON`T HAVE MUCH TIME TO
RECOVER BEFORE WE CLOUD UP AND THE RAIN ARRIVES...FORECAST SOUNDINGS
DURING PRECIP TIME ARE STABLE IN THE LOW LEVELS...SO WE`RE NOT
EXPECTING ANY THUNDER ATTM. GIVEN THE LACK OF NOTABLE PREFRONTAL
MOISTURE ADVECTION...COMBINED WITH THE SPEED OF THE SYSTEM...QPF
VALUES EXPECTED TO BE LESS THAN A THIRD INCH. OTHERWISE...IT WILL
TURN BREEZY FROM THE SOUTHWEST THIS MORNING AS THE PRES GRADIENT
INCREASES WITH THE COLD FRONT APPROACHING. AS FOR TEMPS...AFTER A
CHILLY START TO THE DAY WITH TEMPS IN THE MID-UPR 30S ACROSS PARTS
OF OUR CWA...AND RAIN KEEPING THINGS COOL THROUGH MID-DAY...HIGHS
WILL OCCUR FAIRLY LATE IN THE DAY...PERHAPS EVEN IN THE WAKE OF THE
COLD FRONT...AS FORECAST SOUNDINGS SHOW POST-FRONTAL W-TO-NW WINDS
ACTUALLY WARMING THE LOW LEVEL AIRMASS AND HELPING TO WARM TEMPS
INTO THE LOWER 60S BEFORE SUNSET.

FAIR WEATHER WITH MAINLY CLEAR SKIES TONIGHT IN THE WAKE OF THE COLD
FRONT...ALTHOUGH SOME MID AND HIGH CLOUDS IN ADVANCE OF THE NEXT
NORTHERN STREAM WAVE MAY MOVE ACROSS LATE TONIGHT OR EARLY TUESDAY
MORNING...PERHAPS IN THE FORM OF SOME OROGRAPHIC CIRRUS. AS FOR
TEMPS...CAA WILL BE FAIRLY SUBTLE AS DEMONSTRATED BY LOW LEVEL
THICKNESSES DROPPING ONLY ABOUT 10-15M FROM PRE-FRONTAL VALUES.
STILL BELOW NORMAL THOUGH...WITH LOWS TONIGHT EXPECTED TO RANGE FROM
THE UPPER 30S ACROSS THE TRIAD TO LOWER 40S ACROSS THE SANDHILLS.

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 315 AM MONDAY...

THE ACTIVE NW FLOW WILL CONTINUE...WITH THE NEXT SHORT WAVE MOVING
SE ACROSS THE GREAT LAKES AND NORTHERN MID-ATLANTIC REGIONS DURING
THIS TIME. ITS ATTENDANT SFC FRONT...WHICH WILL BE MOVING ACROSS THE
OHIO VALLEY AROUND MID-DAY...WILL PROGRESS EAST AND SOUTHWARD...
CROSSING CENTRAL NC DURING THE EVENING TUESDAY. SINCE THERE WILL BE
LITTLE OR NO OPPORTUNITY FOR MOISTURE RECOVERY BEHIND TODAY`S
FRONT...THE FROPA TUESDAY EVENING IS EXPECTED TO BE DRY.
OTHERWISE...850MB FLOW IS PROGGED TO SHIFT FROM NW TO SW AND
INCREASE AHEAD OF THE APPROACHING WAVE...SO LOOK FOR TEMPS TO TREND
WARMER...WITH HIGHS IN THE UPPER 60S TO AROUND 70.

HIGH PRESSURE WILL BEGIN BUILDING INTO OUR AREA BEHIND THE FRONT
TUESDAY NIGHT...SO LOOK FOR CLEARING SKIES. DESPITE POST-FRONT CAA
AS NOTED BY DOWNWARD TREND IN LOW LEVEL THICKNESS VALUES...IT WILL
BE BREEZY TUESDAY NIGHT WITH HIGH PRESSURE IS BUILDING
SOUTHWARD...SO LOOK FOR LOWS IN THE LOW TO MID 40S.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 355 AM MONDAY...

DEEP LAYER RIDGING...INCLUDING A RELATIVELY COOL CANADIAN SFC
HIGH...WILL BUILD EAST ACROSS THE CAROLINAS WED AND WED NIGHT. THE
RESULT WILL BE MAINLY CLEAR AND COOLER THAN AVG CONDITIONS...WITH
TEMPERATURES MOSTLY IN THE 60S FOR HIGHS...AND MIDDLE 30S TO LOWER
40S FOR LOWS...BASED ON GOOD TO EXCELLENT RADIATIONAL COOLING AND
PROJECTED LL THICKNESS VALUES AROUND 1340 METERS AT 12Z THU.

RETURN FLOW AND A DEVELOPING LL WAA REGIME WILL DEVELOP THU AND THU
NIGHT...BUT BOTH MOISTURE AND LIFT APPEAR MORE MEAGER THAN
PREVIOUSLY FORECAST IN PART DUE TO A MORE SHEARED SOLUTION FOR A
SOUTHERN STREAM SHORTWAVE TROUGH FORECAST TO CROSS THE AREA THU...
SO ANY ASSOCIATED RAIN CHANCES WOULD APPEAR TO BE SLIGHT AT BEST.
WARMER WITH HIGHS IN THE 70S...AND LOWS MOSTLY IN THE UPPER
50S...WITH INCREASING HUMIDITY LEVELS AS SFC DEWPOINTS CLIMB INTO
THE 50S.

TIMING DIFFERENCES REMAIN IN MODEL SOLUTIONS REGARDING THE APPROACH
OF A NORTHERN STREAM TROUGH AND ASSOCIATED SFC COLD FRONTAL PASSAGE
DURING THE END OF THE WEEK AND INTO THE WEEKEND. THE GFS REMAINS ON
THE SLOW SIDE OF MODEL SOLUTIONS...WITH FROPA ON SAT...WHILE THE
ECMWF...WITH SUPPORT OF THE EC ENSEMBLES...INDICATES FROPA FRI
NIGHT. WILL FOLLOW WPC PREFERENCE TOWARD THE EC CAMP AND INDICATE
THE BEST CHANCE OF SHOWERS FRI NIGHT...WITH UNFAVORABLE DIURNAL
TIMING FOR ANY THUNDER. WARM IN ADVANCE OF THE FRONT...WITH HIGHS
AROUND 80 DEGREES OR BETTER FRI...BUT TURNING COOLER AND TRENDING
CLOSER TO AVG FOR THE WEEKEND...WITH SOME UPPER 30S PROBABLE SUN
MORNING.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AS OF 640 AM MONDAY...

PREFRONTAL SHOWERS ARE MOVING EAST ACROSS THE NC MOUNTAINS AND
FOOTHILLS ATTM.  AHEAD OF THESE SHOWERS...MID CLOUDS HAVE INCREASED
ACROSS THE PIEDMONT AND WILL CONTINUE LOW LOWER AS THE SHOWERS
APPROACH. FLT CONDITIONS EXPECTED TO BECOME MVFR WITH LOCAL IFR AS
THE LIGHT RAIN ARRIVES OVER THE NEXT FEW HOURS.  RAIN IS STILL
EXPECTED TO BEGIN AT INT/GSO BY 12Z...RDU BY 1330Z...AND RWI/FAY BY
1430Z. THE RAIN SHOULD BE FAIRLY SHORT-LIVED...WITH VFR CONDITIONS
TO RETURNING TO INT/GSO BY 18Z...AND RDU/RWI/FAY BY 21-22Z. CURRENT
KRAX VWP IS STILL INDICATING SW WINDS OF 50-55KT AT 1 TO 2 K
FT...WHILE SFC WINDS ARE AROUND 10-12KT. AS SUCH...WILL CONTINUE TO
INCLUDE LLWS IN THE TAFS THROUGH AT LEAST LATE MORNING. WHILE THE
LLWS MAY DECREASE LATER THIS MORNING...SFC WINDS ARE EXPECTED TO
INCREASE WITH 20+KT GUSTS THROUGH 30/23Z. FOR TONIGHT (AFT
30/23Z)...VFR CONDITIONS ARE EXPECTED WITH MAINLY MID-HIGH CLOUDS.

BEYOND TONIGHT...LOOK FOR MAINLY VFR CONDITIONS THROUGH THURSDAY.
CONDITIONS MAY BRIEFLY DETERIORATE THURSDAY NIGHT THROUGH
FRIDAY...AND AGAIN ON SATURDAY ASSOC WITH INCREASED CLOUDS AND
PRECIP CHANCES WITH AN APPROACHING COLD FRONT.

&&

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

&&

$$

SYNOPSIS...RAH
NEAR TERM...RAH
SHORT TERM...RAH
LONG TERM...RAH
AVIATION...RAH


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