Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 230844
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
444 AM EDT WED APR 23 2014

.SYNOPSIS...
A COLD FRONT OVER EASTERN VIRGINIA WILL MOVE OFF THE COAST
TODAY. HIGH PRESSURE OVER THE GREAT LAKES AND OHIO VALLEY
WILL QUICKLY BUILD EAST PASSING OVERHEAD TONIGHT AND THURSDAY.
ANOTHER COLD FRONT WILL CROSS THE AREA FROM THE WEST ON FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 430 AM EDT WEDNESDAY...

DEWPOINTS ARE ON THE WAY DOWN COURTESY OF A COLD FRONT WHICH
PASSED THROUGH THE AREA LAST NIGHT. THIS FRONT WILL MOVE OFF
THE MID ATLANTIC COAST TODAY...PRESSURE GRADIENT BETWEEN THE
DEPARTING FRONT AND HIGH PRESSURE OVER THE GREAT LAKES AND OHIO
VALLEY...RESULTING IN BREEZY CONDITIONS THROUGHOUT THE DAY.

THE 1022MB SURFACE HIGH OVER THE GREAT LAKES AND OHIO VALLEY IS OF
CANADIAN ORIGIN...A COOL DRY CONTINENTAL AIRMASS. IN SPITE OF ITS
COOL NATURE...THE LATE APRIL SUN ANGLE SHOULD HELP BALANCE SOME
OF THE COLD AIR ADVECTION...YIELDING HIGHS IN THE 60S WITH THE
EXCEPTION OF THE HIGHER ELEVATIONS WHICH MAY STRUGGLE TO GET ABOVE
50 DEG F.

THIS COOL AIRMASS WILL SET THE STAGE FOR A CRISP NIGHT TONIGHT.
WINDS WILL DIMINISH AFTER SUNSET...AND DECOUPLE AFTER MIDNIGHT AS
THE SURFACE HIGH BUILDS OVERHEAD. MODEL GUIDANCE SUGGESTS THE
ENTIRE CWA WILL DIP INTO THE 30S OVERNIGHT...LOWS RANGING FROM 30
DEGREES IN THE SHELTERED MOUNTAIN VALLEYS TO THE MID/UPPER 30S IN
THE PIEDMONT. THIS ALSO SUGGESTS POSSIBILITY OF FROST...BUT BASED
ON THE DRYNESS OF THE AIRMASS...DEWPOINTS IN THE 20S...LACK OF
MOISTURE MAY PROHIBIT MUCH FROST. ATTM WILL ADVERTISE PATCHY
FROST...BUT THINK THIS WILL ONLY OCCUR IN AREAS WHERE THE WINDS
COMPLETELY DECOUPLE AND THERE IS ENOUGH MOISTURE TO PROMOTE
FROST...SUCH AS CREEK BOTTOMS...ETC.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM EDT WEDNESDAY...

SURFACE HIGH PRESSURE WILL QUICKLY MOVE OVER THE REGION AND OFF THE
SOUTHEAST COAST ON THURSDAY. BY THE AFTERNOON...AN UPPER LEVEL RIDGE
AND SOUTHERLY FLOW WILL BRING NEAR NORMAL TEMPERATURES TO THE
FORECAST AREA. CLOUDS WILL INCREASE THURSDAY NIGHT WITH PREFRONTAL
SHOWERS ENTERING THE WEST BY SUNRISE FRIDAY MORNING. THESE SHOWERS
AND POSSIBLE A FEW THUNDERSTORMS...WILL MOVE EAST OF THE BLUE RIDGE
BY EARLY AFTERNOON AND EXIT THE AREA BY SUNSET. MODELS ARE IN FAIRLY
GOOD AGREEMENT WITH START/ENDING PRECIP TIMING WITH THE GFS A COUPLE
OF HOURS FAST AND THE ECM AN HOUR OR SO SLOWER. DESPITE THE
RAIN...TEMPERATURES WILL BE A FEW DEGREES WARMER ON FRIDAY. NOT MUCH
COLD AIR BEHIND THE FRONT WITH LOWS FRIDAY NIGHT IN THE 40S ACROSS
THE WEST AND LOWER 50S EAST.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 345 PM EDT TUESDAY...

MODELS START TO BECOME DIVERGENT ON SATURDAY AS TO HOW FAR SOUTH A
COLD FRONT WILL PUSH FROM THE GREAT LAKES. THE GFS IS MORE AGGRESSIVE
IN TAKING THE COLD FRONT ACROSS OUR REGION DURING THE AFTERNOON...
WHILE THE ECMWF HAS FLIP-FLOPPED FROM ITS PREVIOUS FORECAST
SOLUTION...STALLING THE FRONT NORTH OF THE OHIO RIVER. THIS REMAINS
A LOW CONFIDENCE PORTION OF THE FORECAST BUT...IN EITHER CASE...BOTH
MODELS HAVE OUR AREA RELATIVELY DRY THROUGH THE REMAINDER OF THE
WEEKEND...WITH RAIN CHANCES INCREASING SUNDAY NIGHT AS OUR NEXT LOW
PRESSURE SYSTEM DEVELOPS ACROSS THE PLAINS... BRINGING RAIN TO THE
AREA ON MONDAY. EXPECT HIGHS IN THE UPPER 60S AND 70S FOR SATURDAY
AND SUNDAY...WITH RAIN BRINGING COOLER TEMPERATURES IN THE LOW TO
MID 60S FOR MONDAY. THE OVERNIGHTS ARE EXPECTED TO REMAIN ABOVE
FREEZING MOST LOCATIONS EXCEPT PERHAPS THE DEEPER VALLEY BOTTOMS.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
AS OF 200 AM EDT WEDNESDAY...

COLD FRONT WILL BE EAST OF THE AREA BY DAYBREAK WEDNESDAY. ASIDE
FOR SOME SCT MID CLOUD...VFR CONDITIONS PREVAIL. BIGGEST BY-
PRODUCT OF THE FRONTAL PASSAGE WILL BE THE GUSTY SURFACE WINDS.
WINDS TODAY WILL BE OUT OF THE NORTHWEST...SUSTAINED 12-18KTS WITH
GUSTS OF 22-28KTS. WINDS WILL DIMINISH TONIGHT WITH RETURN OF
LIGHT SOUTHWESTERLY FLOW THURSDAY AS HIGH PRESSURE PASSES OVHD AND
OFF THE MID ATLANTIC COAST.

EXTENDED AVIATION DISCUSSION...

A COLD FRONT WILL CROSS THE AREA EARLY FRIDAY...WITH A BRIEF
PERIOD OF MVFR RESTRICTIONS POSSIBLE AS SHOWERS/ISOLATED STORMS
MOVE EAST WITH THE FRONT THROUGH THE AREA. STRONG HIGH PRESSURE
BUILDS IN FRIDAY NIGHT INTO SATURDAY WITH VFR EXPECTED UNDER GUSTY
NORTHWEST WINDS. WINDS DIMINISH SATURDAY NIGHT FOLLOWED BY HIGH
PRESSURE PASSING OVHD SUNDAY WITH FAIR DRY WEATHER.

&&

.FIRE WEATHER...
RED FLAG WARNING IN EFFECT FROM THE VIRGINIA BLUE RIDGE NORTHWARD
INTO NORTH CENTRAL VA FOR STRONG NORTHWEST WINDS AND LOW HUMIDITY.
WINDS TODAY WILL RANGE FROM 15 TO 20 MPH SUSTAINED...WITH GUSTS
OF 25 TO 30 MPH. HUMIDITY MINIMUMS NEAR 20 PERCENT WILL BE COMMON
THIS AFTERNOON. IN ADDITION...IT HAS BEEN 7 DAYS SINCE MEASURABLE
RAINFALL HAS OCCURRED IN ROANOKE VALLEY AND THE IMMEDIATE BLUE
COUNTIES...INCLUDING THE NEW RIVER AND SHENANDOAH VALLEYS. THIS
HAS ALLOWED LEAVES AND BRUSH TO BECOME DRY AND VERY RECEPTIVE TO
FIRE...10 HOUR FUEL MOISTURE NEAR 7 PERCENT.

CONCERN TODAY IS FOR RAPID FIRE SPREAD IF A WILDFIRE OCCURS.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...RED FLAG WARNING FROM 11 AM THIS MORNING TO 8 PM EDT THIS
     EVENING FOR VAZ007-009>020-022>024-032>035-047.
NC...NONE.
WV...NONE.

&&

$$
SYNOPSIS...PM
NEAR TERM...PM
SHORT TERM...RCS
LONG TERM...NF
AVIATION...PM
FIRE WEATHER...PM



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