Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 181941
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
341 PM EDT FRI APR 18 2014

.SYNOPSIS...
AN AREA OF LOW PRESSURE MOVING THROUGH THE SOUTHEASTERN UNITED
STATES WILL PUSH SOME PRECIPITATION INTO NORTHWEST NORTH
CAROLINA...AND INTO VIRGINIA UP TO ROUTE 460...TONIGHT AND TOMORROW.
HIGH PRESSURE WILL THEN BUILD ALONG THE EASTERN SEABOARD AND
BRING FAIR WEATHER TO THE REGION INTO THE FIRST PART OF NEXT
WEEK. HOWEVER...A COLD FRONT WILL MOVE THROUGH ON TUESDAY WITH
SHOWERS AND THUNDERSTORMS...FOLLOWED BY BREEZY CONDITIONS AND DRY
WEATHER FOR MIDWEEK.
&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 230 PM EDT FRIDAY...

MAIN CONCERN CONTINUES WITH NORTHWARD PROGRESSION OF CLOUDS/RAINFALL
OVER THE NEXT 24 HOURS ASSOCIATED WITH THE VERTICALLY STACKED
COASTAL LOW THAT WILL DRIFT EAST ACROSS NRN FLORIDA TONIGHT AND OFF
THE SE COAST SATURDAY. THIS SYSTEM WILL PUSH DEEPER MOISTURE
NORTH OVERNIGHT WITH A DEVELOPING UPSLOPE COMPONENT INTO THE NW NC
MOUNTAINS LATE. HOWEVER MODELS REMAIN IN SIMILAR CAMPS AS BEFORE
WITH THE NAM KEEPING MOST PRECIP TO THE SOUTH...WHILE THE GFS HAS
A DEFORMATION BAND ACROSS SRN VA/NW NC BY MORNING...LEAVING THE
CANADIAN AND NEW EC BASICALLY IN BETWEEN WITH MOST RAINFALL ACROSS
THE SOUTH/EAST BY EARLY SAT. LATEST CONSENSUS INCLUDING WPC
OUTPUT SUGGESTS A SLOWER SOLUTION IN ORDER TONIGHT GIVEN DRY
ADVECTION FROM HIGH PRESSURE TO THE NORTH AND GRADUAL DEVELOPMENT
OF DEEP CONVECTION ALONG THE COAST EARLY SAT. THUS HAVE CUT BACK
ON POPS ENTERING THE SOUTH THIS EVENING WITH BETTER LIFT AND
COLUMN SATURATION AFTER MIDNIGHT NW NC INTO SOUTHERN VA EARLY SAT
WHERE MAINTAINED LOW LIKELYS FOR LIMITED QPF. NORTHWARD EXTENT
ALSO IFFY AS APPEARS THE BLUE RIDGE TO SERVE AS A BACKBOARD WITH
MID LEVEL DRY HOLDING ANY PRECIP ALONG/SOUTH OF HIGHWAY 460...SO
MAINLY CHANCE POPS IN THESE SPOTS. OTRW MAINLY CLOUDY AND DRY ELSW
WITH UNIFORM LOWS MOSTLY IN THE UPPER 30S TO MID 40S.

GUIDANCE SHOWS THE DEFORMATION AXIS STRETCHING OUT ALONG OR SOUTH
OF THE VA/NC BORDER SAT UNDER CONFLUENCE ALOFT AND SOUTH OF HIGH
PRESSURE BUILDING IN FROM THE NORTH. AGAIN LOOKS LIKE MOST -RA/DZ
ALONG AND SOUTH OF THE BORDER BUT A TIGHT GRADIENT LIKELY FROM LOW
CLOUDS/PRECIP SOUTH TO HIGH/MID CLOUDS AND LITTLE -RA NORTH AND
WEST. ENSEMBLES SHOW PRECIP PIVOTING ACROSS THE EAST THROUGH MUCH
OF SATURDAY BUT SEEMS OVERDONE WITH THE LOW LEVEL FLOW MORE NE
THAN EAST WHICH SOMETIMES ACTS TO LIMIT PRECIP INTO AN ENHANCED
WEDGE. THEREFORE MAINTAINED CONTINUITY WITH LINGERING LIKELY POPS
FAR SOUTH/SE DURING THE MORNING AND CHANCES UP TO 460...THEN
DRYING FROM NW TO SE SAT AFTERNOON WITH MOST RAINFALL EXITING
LATE. HIGH TEMPS VERY TRICKY WITH LARGE MOS SPREADS ATTM PENDING
DEGREE OF CLOUDS AND RAIN WHICH COULD KEEP SOME SPOTS IN THE 40S
TO AROUND 50 IF PRECIP IS MORE WIDESPREAD. OTRW STAYING CLOSER TO
THE COOLER MAV MOS SOUTH/EAST BUT SLIGHTLY WARMER NORTH WHERE SOME
SUN POSSIBLE.
&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 300 PM EDT FRIDAY...

BY SATURDAY NIGHT...THE LOW WHICH AFFECTED US ON SATURDAY SHOULD
SINK FAR ENOUGH SEWD TO PULL THE PCPN SHIELD OUT OF OUR AREA.
THEN...HIGH PRESSURE RIDGING DOWN THE COAST COMBINED WITH NELY
FLOW AROUND THE LOW WILL KEEP A BRISK WIND OVER THE PIEDMONT.
NEXT SYSTEM BEGINS TO APPROACH ON MONDAY AND MODELS SPIT OUT SOME
LIGHT QPF WITH WEAK DYNAMIC SUPPORT. WILL OPT TO KEEP MONDAY DRY
AND LEAVE POPS JUST BELOW THRESHOLD.
&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 200 PM EDT FRIDAY...

MAIN WEATHER MAKER THOUGH THE EXTENDED WILL BE CFROPA ON TUESDAY.
THE FRONT LOOKS TO HAVE GOOD SUPPORT...AND AREAS EAST OF THE BLUE
RIDGE LOOK TO DESTABILIZE A BIT AHEAD OF THE FRONT TUESDAY
AFTERNOON. WILL GO WITH LLIKELY POPS AND CONFINE CHC THUNDER TO
ERN AREAS. NOT SEEING MUCH IN THE DATA TO INDICATE MORE THAN
GENERAL THUNDERSTORMS ATTM.

BELIEVE THERE WILL BE A CHC FOR SOME UPSLOPE RAIN SHOWERS IN CAA
WEST OF THE BLUE RIDGE AND WILL INDICATE THIS FOR WEDNESDAY
NIGHT...AND WEDNESDAY LOOKS BREEZY AS HIGH PRESSURE BUILDS IN WITH
QUIET WX FOR THURSDAY.
&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
AS OF 1240 PM EDT FRIDAY...

HAVE BROKEN INTO OVERALL VFR EARLY THIS AFTERNOON AND SHOULD
MAINTAIN INTO EARLY THIS EVENING WITH EXTENSIVE HIGH CLOUDS ON TOP
OF SCTD LOW CLOUDS. STILL EXPECT CIGS TO LOWER OVERNIGHT BUT
DEPTH OF MOISTURE REMAINS IN QUESTION UNDER DRY MID LEVELS AND
DEVELOPING NE FLOW LATER ON. MODELS REMAIN VARIED ON HOW FAR NORTH
TO TAKE LOWER CIGS AND RAINFALL AFTER MIDNIGHT WITH AN ENSEMBLE
BLEND PROVIDING A RANGE FROM MOSTLY VFR OVERNIGHT AT LWB TO
DEVELOPING IFR ALONG AND EAST OF THE BLUE RIDGE BY DAYBREAK
SATURDAY. APPEARS MVFR TO OCNL IFR MOST LIKELY FROM ROA-LYH SOUTH
TO DAN WHILE A PERIOD OF MVFR LIKELY AT BCB AND POSSIBLE AT BLF
ALTHOUGH LOW CONFIDENCE AT THIS POINT. RAINFALL INDUCED VSBY
REDUCTIONS ALSO IFFY WITH MVFR LIKELY AT DAN AND PERHAPS ROA/LYH
IF THINGS SATURATE ENOUGH BY EARLY SATURDAY WHICH APPEARS
POSSIBLE. ELSW INCLUDING SOME -RA/DZ MENTION AT BCB AND BLF LATE
BASED ON LATEST NON NAM GUIDANCE TRENDS.

LIGHT/VRBL WINDS TO PERSIST THIS AFTERNOON...THEN BECOMING
NORTH/NE TONIGHT WITH SPEEDS INCREASING...PUSHING GUSTS TO 20 KTS
OUT EAST BY MORNING.

POOR FLYING CONDITIONS COULD PERSIST OVER THE SOUTH AND EAST INTO
SATURDAY AFTERNOON WITH THE BELT OF DEEPER MOISTURE UNDER THE
UPPER LOW SLOW TO EXIT. PERIODS OF -RA/DZ MAY ALSO LINGER EAST OF
THE BLUE RIDGE WHERE ROA/LYH/DAN COULD GET STUCK IN MVFR TO IFR
CIGS AND SOME LIMITED VSBY REDUCTION PENDING NORTHWARD EXTENT OF
THE RAINFALL ESPCLY THROUGH MIDDAY.

EXTENDED AVIATION DISCUSSION...
THE UPPER LOW SLOWLY EXITS TO THE EAST SUNDAY AND HIGH PRESSURE
RETURNS BRINGING A RETURN TO VFR CONDITIONS INTO EARLY NEXT WEEK.
THE NEXT COLD FRONT APPROACHES MONDAY NIGHT WITH MORE SHOWERS AND
POSSIBLE THUNDERSTORMS INCLUDING PERIODS OF MVFR. FRONT EXITS
TUESDAY NIGHT RESULTING IN A RETURN TO VFR WEDNESDAY EXCEPT FOR
MVFR CIGS OVER THE FAR WESTERN SITES IN SE WEST VA.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.

&&

$$
SYNOPSIS...MBS
NEAR TERM...JH
SHORT TERM...MBS
LONG TERM...MBS
AVIATION...JH/RAB



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