Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 181703
AFDRNK

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

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN ACROSS THE NORTHEAST U.S. THROUGH
SATURDAY...WHILE AN AREA OF LOW PRESSURE DEVELOPS AND MOVES SLOWLY
EAST THROUGH THE SOUTHEAST STATES...MOVING OFF THE SOUTHEAST U.S.
COAST MONDAY. THIS SYSTEM WILL BRING LIGHT RAIN TO THE SOUTHERN
PORTIONS OF THE FORECAST AREA TONIGHT AND SATURDAY. AN UPPER
TROUGH AND ASSOCIATED COLD FRONT WILL MOVE THROUGH THE REGION FROM
THE WEST EARLY NEXT WEEK WITH THE NEXT CHANCE FOR SHOWERS AND
POSSIBLY THUNDERSTORMS.
&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1025 AM EDT FRIDAY...

THICK CANOPY OF HIGH CLOUDS CONTINUES TO SHEAR NE ACROSS MUCH OF
THE REGION THIS MORNING WITH SOME LINGERING LOW CLOUDS ALONG/EAST
OF THE BLUE RIDGE UNDER THE WEDGE. PRECIP REACHING THE GROUND WITH
THE STRONG SE UPPER LOW REMAINS WELL TO THE SOUTH ATTM WITH MOST
SHORT TERM MODELS AND THE LATEST NAM KEEPING MOST OUT OF THE CWA
UNTIL THIS EVENING. THEREFORE GIVEN DRY MID LEVELS OFF MORNING
SOUNDINGS TRIMMED BACK POPS OVER THE FAR SOUTH THIS AFTERNOON
WHILE KEEPING EXTENSIVE CLOUD COVER GIVEN GOING ADVECTION OF
MOISTURE FROM THE SOUTH. THIS ALONG WITH AN OVERALL EAST/NE
TRAJECTORY WILL LIKELY KEEP HIGH TEMPS EVEN COOLER SO LOWERED A
FEW DEGREES MOST AREAS OUTSIDE OF THE FAR WESTERN SLOPES WITH MOST
AGAIN STUCK IN THE 50S THIS AFTERNOON.

PREVIOUS DISCUSSION AS OF 445 AM EDT FRIDAY...

INCREASINGLY COMPLICATED FORECAST THROUGH THE NEAR TERM THANKS TO
DEEPENING LOW PRESSURE AREA ALOFT ACROSS THE SOUTHEAST STATES.
MODELS IN GENERAL AGREEMENT ON SYNOPTIC PATTERN...BUT QPF AND
NORTHWARD EXTENT OF PCPN PROBLEMATIC. GFS BRINGS OVER AN INCH OR
RAIN AS FAR NORTH AS SOUTHERN VA OVERNIGHT...WHILE
NAM/ECMWF/CANADIAN KEEP PCPN AMOUNTS TO AROUND 1/4 INCH IN
SOUTHERN VA AND PERHAPS UP TO 1/2 INCH IN NC COUNTIES. GFS HAS
BEEN CONSISTENT LAST SEVERAL RUNS IN DEVELOPING A BAND OF HEAVIER
RAIN ACROSS SW/SC VA...BUT THIS HAS NEVER BEEN INDICATED BY THE
OTHER MODELS. WPC INDICATES GFS IS ODD SOLUTION AND AS A RESULT
HAVE CHOSEN TO DISCARD HEAVIER RAINFALL AND FURTHER NORTHWARD
EXTENT...EVEN INTO WV...INDICATED BY GFS. NONETHELESS...ALL MODELS
HAVE TRENDED WETTER...FURTHER NORTH...WITH -RA POSSIBLY BEGINNING
IN WESTERN NC EVEN LATE THIS AFTERNOON. EXTENSIVE HIGH CLOUD COVER
HAS ALREADY OVERSPREAD THE REGION...AND SOME LOW CLOUDS CREEPING
INTO EASTERN PIEDMONT COUNTIES.

TEMPERATURES WILL RISE VERY LITTLE TODAY AND BE QUITE UNIFORM
ACROSS THE REGION THROUGH THE NEAR TERM...MAINLY 50S FOR HIGHS
TODAY AND 40S FOR LOW TONIGHT...WITH A FEW LOW 60S POSSIBLE IN FAR
SW VA. E-NE FLOW WILL TEND TO KEEP AREAS EAST OF THE ALLEGHANY
FRONT COOLER THAN NORMALLY COLDER WESTERN AREAS. MODEL GUIDANCE
SIMILAR AND INTERESTING TO NOTE THAT ECMWF GRIDDED OVERNIGHT TEMPS
NEAR 45 ACROSS ENTIRE CWA.

WITH RESPECT TO FROST ADVISORY...HAVE CANCELLED ALL EXCEPT FOR A
FEW OF THE ORIGINAL INCLUDED COUNTIES AS CLOUDS AND EAST FLOW HAVE
PREVENTED DECOUPLING. IT NEVER EVEN GOT BELOW 40 AT DAN/LYH AS A
RESULT. OPTED TO KEEP THE SOUTHERN SHENANDOAH VALLEY COUNTIES IN
THROUGH 8 AM AS MESO OBS SHOW READINGS IN THE LOW 30S THERE
YET WITH CALM WINDS...SO FROST QUITE LIKELY THERE.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
AS OF 230 AM EDT FRIDAY...

SATURDAY MORNING...ONSHORE FLOW IN ASSOCIATION WITH A SLOW MOVING
AREA OF LOW PRESSURE OVER GEORGIA IS STILL EXPECTED TO BE BRINGING
PATCHY LIGHT RAIN TO THE SOUTHERN THIRD OF THE FORECAST AREA. AS THE
DAY PROGRESSES...THE LOW WILL SHIFT SLOWLY EASTWARD...AND LIKEWISE
WILL THE PRECIPITATION. CLOUD COVER ALSO WILL DECREASE IN COVERAGE
FROM NORTHWEST TO SOUTHEAST. BY EARLY SATURDAY EVENING...THE
PRECIPITATION IS EXPECTED TO OUT OF THE AREA...WITH THE CLOUD COVER
CONTINUING TO EXIT. FOR HIGHS ON SATURDAY...HAVE FAVORED NUMBERS
AROUND OR SLIGHTLY COOLER THAN THAT OF THE MAV MOS GIVEN THE NAM HAS
SOLUTION WITH LESS CLOUD COVER AND PRECIPITATION. LIKEWISE FOR
SATURDAY NIGHT...HAVE LEANED MORE TOWARD THE MAV MOS GUIDANCE.

HEADING INTO SUNDAY...THE CLOSED LOW OVER THE SOUTHEAST U.S.
CONTINUES ITS PROGRESSION EASTWARD INTO THE ATLANTIC. OVER OUR
REGION...HIGH PRESSURE WILL BUILD OVERHEAD CONCURRENT TO AN UPPER
RIDGE DEVELOPING OVER THE EASTERN U.S. THE RESULT WILL BE A
PRECIPITATION-FREE FORECAST ON SUNDAY AND MONDAY WITH A TREND TOWARD
MODERATING TEMPERATURES.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 330 PM EDT WEDNESDAY...

MONDAY LOOKS TO BE DRY WITH THE ATLANTIC SYSTEM WELL OUT
TO SEA AND A WEAK RIDGE OF HIGH PRESSURE ALONG THE EASTERN
SEABOARD AND SEASONAL TEMPERATURES. MODELS BRING A FAIRLY
STRONG FRONT THROUGH THE CWA ON TUESDAY WITH GOOD CHANCES FOR
SHOWERS AND POSSIBLE THUNDERSTORMS DEPENDING ON MESOSCALE
FORCING IN PLACE AT THAT TIME. SKIES SHOULD CLEAR TUESDAY
NIGHT INTO WEDNESDAY WITH NORTHWEST FLOW AND COOLER TEMPS BEHIND
THE FRONT.

&&

.AVIATION /18Z 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...RAB
NEAR TERM...JH/KK/KM/RAB
SHORT TERM...DS
LONG TERM...PC
AVIATION...JH/RAB



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