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000
FXUS62 KRAH 220202
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1002 PM EDT MON APR 21 2014

.SYNOPSIS...
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HIGH PRESSURE WILL EXTEND OVER THE REGION OVERNIGHT THEN
SHIFT OFFSHORE TUESDAY MORNING. A COLD FRONT WILL MOVE ACROSS THE
STATE TUESDAY AFTERNOON AND EVENING. HIGH PRESSURE WILL BUILD BACK
IN BEHIND THE FRONT FOR WEDNESDAY THROUGH THURSDAY.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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AS OF 1002 PM MONDAY...

A RIDGE OF HIGH PRESSURE AT THE SURFACE AND ALOFT OVER NC THIS
EVENING WILL WEAKEN AS IT DRIFTS EWD OVERNIGHT INTO TUESDAY MORNING.
W-SW FLOW ALOFT IN THE WAKE OF THE DEPARTING RIDGE WILL ADVECT
MOISTURE INTO OUR REGION...RESULTING IN PATCHES OF MID-HIGH LEVEL
CLOUDINESS. SFC DEWPOINTS ARE AVERAGING SEVERAL DEGREES BELOW MOS
GUIDANCE...MAINLY ACROSS THE NORTHWEST PIEDMONT....INDICATIVE OF HOW
DRY THE AIR MASS IS UNDERNEATH THIS RIDGE AND HOW MODELS MAY BE
WEAKENING ITS INFLUENCE OVER CENTRAL NC TOO QUICKLY

PER SATELLITE IMAGERY AND TRENDS...BULK OF HIGH CLOUDS PATCHY WITH
MORE SOLID OVERCAST WELL WEST OF CENTRAL NC. PER THIS TREND AND
CHARACTER OF AIR MASS TO BE DRIER THAN PREDICTED...SKIES SHOULD BE
NO WORSE THAN PARTLY CLOUDY THROUGH MOST OF THE NIGHT WITH JUST AN
HOUR OR TWO OF MOSTLY CLOUDY SKIES POSSIBLE...MAINLY IN THE WEST.

AIR MASS CONTINUES TO MODIFY AND WITH HIGH LEVEL MOISTURE ON THE
INCREASE...EXPECT TEMPS OVERNIGHT TO AVERAGE 5-8 DEGREES WARMER THAN
LAST NIGHT. EXPECT A DECENT RANGE BETWEEN URBAN AND RURAL AREAS WITH
MIN TEMPS IN THE URBANIZED AREAS NEAR 50-LOWER 50S WHILE MORE
SHELTERED LOCATIONS SHOULD SEE MIN TEMPS IN THE MID-UPPER 40S.
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&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
AS OF 1258 PM MONDAY...

SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED TO DEVELOP
ALONG THE COLD FRONT AS IT PUSHES EAST OFF THE BLUE RIDGE EARLY
AFTERNOON. THESE SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS SHOULD
PROGRESS ACROSS OUR REGION DURING PEAK HEATING. HOWEVER... WEAK
CONVERGENCE ALONG THE FRONT... MEAN WESTERLY FLOW... LIMITED
INSTABILITY (SURFACE DEW POINT RECOVERY ONLY IN THE LOWER TO MID
50S)... AND WEAK LAPSE RATES SUGGESTS THAT ONLY ISOLATED TO
SCATTERED THUNDERSTORM OF THE GENERAL VARIETY. QPF OF LESS THAN 0.25
OF AN INCH IS EXPECTED. SW SURFACE WINDS SHOULD INCREASE AFTER
SUNRISE WITH MIXING TO 10-20 MPH... WITH GUSTS TO 25-30 MPH IN THE
AFTERNOON. THE WINDS WILL GRADUALLY BECOME WESTERLY AS THE FRONT
SLIPS THROUGH DURING THE AFTERNOON. IN GENERAL... SKIES ARE EXPECTED
TO BE PARTLY SUNNY... THEN BECOME MOSTLY CLOUDY. HIGHS IN THE MID TO
UPPER 70S EXPECTED NW... TO AROUND 80-82 OR SO ELSEWHERE. THE SKIES
WILL CLEAR TUESDAY NIGHT AS THE WINDS BECOME NW AND DIMINISH TO 10
MPH OR LESS LATE. TURNING COOLER WITH LOWS IN THE 40S.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 245 PM MONDAY...

WED-THU: DRY CONDITIONS WILL RULE IN THIS PERIOD DUE TO SYNOPTIC
SUBSIDENCE ASSOC/W RISING HEIGHTS ATTENDANT AN UPPER LEVEL RIDGE
BUILDING EAST FROM THE CENTRAL CONUS TO THE EASTERN SEABOARD. EXPECT
TEMPS SEVERAL DEGREES BELOW NORMAL FOR THIS TIME OF YEAR...RANGING
FROM THE UPPER 60S TO LOWER 70S ON WED AND LOWER TO MID 70S ON THU
IN ASSOC/W SFC HIGH PRESSURE BUILDING INTO THE REGION FROM THE NORTH.

FRI/FRI NIGHT: LOW-LEVEL MOISTURE ADVECTION WILL STRENGTHEN ACROSS
THE CAROLINAS ON FRIDAY AS UPPER LEVEL RIDGING GIVES WAY TO BROAD
CYCLONIC FLOW ALOFT OVER THE REGION. MARGINAL DIURNAL
DESTABILIZATION (500-1000 J/KG MLCAPE) APPEARS LIKELY GIVEN
RELATIVELY STEEP MID-LEVEL LAPSE RATES (~7 C/KM) ATOP AN
INCREASINGLY MOIST BOUNDARY LAYER (CHARACTERIZED BY SFC DEWPOINTS AT
OR SLIGHTLY ABOVE 60F). ALTHOUGH DEEP LAYER SHEAR WILL BE MORE THAN
SUFFICIENT FOR ORGANIZED CONVECTION...DEAMPLIFYING SHORTWAVE ENERGY
IS PROGGED TO TRACK ACROSS THE NORTHERN MID-ATLANTIC AND THE BEST
FORCING /DCVA/ IS EXPECTED TO REMAIN FAR REMOVED FROM CENTRAL NC. AS
A RESULT...UNCERTAINTY PERSISTS WITH REGARD TO WHETHER OR NOT DEEP
CONVECTION (I.E. THUNDERSTORMS) WILL EVEN DEVELOP. WITH THE ABOVE IN
MIND...WILL KEEP PRECIP CHANCES IN THE 30-40% RANGE. HIGHS FRI UPPER
70S TO LOWER 80S...LOWS FRI NIGHT MID/UPPER 50S.

SAT-MON: UNCERTAINTY INCREASES DRAMATICALLY THIS WEEKEND INTO EARLY
NEXT WEEK WITH REGARD TO THE EVOLUTION OF THE UPPER LEVEL PATTERN
OVER THE EASTERN CONUS. THE 12Z ECMWF INDICATES A HIGHER THETA-E
AIRMASS IN PLACE ACROSS THE CAROLINAS WITH AN OCCASIONAL CHANCE FOR
CONVECTION...ESP SUN/MON...WHILE THE GFS INDICATES A COOLER/DRIER
AIRMASS WITH LITTLE CHANCE FOR PRECIPITATION. AT THIS TIME WILL
CONTINUE TO INDICATE A DRY FORECAST WITH NEAR NORMAL MAX/MIN
TEMPERATURES. -VINCENT

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
AS OF 800 PM MONDAY...

MOSTLY VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE CURRENT
TAF PERIOD. LIGHT AND VARIABLE WINDS OVERNIGHT WILL GIVE WAY TO
WESTERLY/SOUTHWESTERLY WINDS ON TUESDAY...WITH SOME GUSTS INTO THE
UPPER TEENS. A COLD FRONT WILL APPROACH AND CROSS THE REGION TUESDAY
AFTERNOON. AHEAD OF THE FRONT...MID/HIGH CLOUDS WILL INCREASE
OVERNIGHT AND THEN THICKEN AND LOWER THROUGHOUT THE DAY ON
TUESDAY...BUT OVERALL SHOULD STAY IN THE VFR RANGE. THE EXCEPTION
MAY BE A PERIOD OF MVFR CIGS/VSBYS...ASSOCIATED WITH A CHANCE OF
SHOWERS AND ISOLATED THUNDERSTORMS...GENERALLY BETWEEN 18-00Z. WINDS
WILL SHIFT TO A MORE NORTHWESTERLY DIRECTION BEHIND THE FRONT...BUT
THIS MAY OCCUR JUST BEYOND THE CURRENT TAF PERIOD (AFTER 00Z/23)...
MAYBE SLIGHTLY BEFORE IN THE TRIAD.

OUTLOOK...VFR CONDITIONS WILL THEN PREVAIL THROUGH AT LEAST THURSDAY
AS HIGH PRESSURE DOMINATES. THE NEXT CHANCE FOR ADVERSE AVIATION
CONDITIONS WILL BE THURSDAY NIGHT/FRIDAY MORNING AS THE HIGH SHIFTS
OFFSHORE AHEAD OF AN APPROACHING FRONT AND MOIST RETURN FLOW SETS UP
OVER THE REGION. THE FRONT IS PROGGED TO CROSS THE REGION FRIDAY
INTO FRIDAY NIGHT...BRINGING WITH IT ANOTHER CHANCE OF SHOWERS
AND/OR STORMS AND ASSOCIATED ADVERSE AVIATION CONDITIONS.

&&

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

&&

$$

SYNOPSIS...BADGETT
NEAR TERM...WSS
SHORT TERM...BADGETT
LONG TERM...VINCENT
AVIATION...KRD