Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 231710
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
110 PM EDT WED APR 23 2014

.SYNOPSIS...
COOL HIGH PRESSURE OVER THE SOUTHERN GREAT LAKES WILL BUILD
QUICKLY EAST PASSING OVERHEAD TONIGHT AND THURSDAY. ANOTHER COLD
FRONT WILL CROSS THE AREA FROM THE WEST ON FRIDAY.
&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 945 AM EDT WEDNESDAY...

HIGH PRESSURE CONTINUES TO BUILD IN WITH ONGOING COOL ADVECTION TO
PREVAIL INTO THIS AFTERNOON WITH THE COLDEST AIR AT 85H PASSING
ACROSS THIS MORNING. THE AIR REMAINS VERY DRY PER ARID PWATS OFF
MORNING SOUNDINGS WHICH SHOULD MIX DOWN WITH HEATING AND THE
LINGERING NW JET ALOFT. THIS WILL ERODE ANY REMAINING LOW CLOUDS
OVER THE FAR NW BY MIDDAY ALLOWING FOR ABUNDANT SUNSHINE UNDER
GUSTY NW WINDS THROUGH THE AFTERNOON. FORECAST HIGH TEMPS LOOK ON
TRACK WITH DOWNSLOPE WARMING OF DRY AIR AN OFFSET TO COOL
ADVECTION OUT EAST WITH HIGHS MOSTLY IN THE 60S TO AROUND 70. COOL
POOL ALOFT UNDER STRONGER NW WINDS SHOULD KEEP MUCH OF THE WEST AT
OR BELOW 60 FOR THE MOST PART ESPCLY HIGHER ELEVATIONS WHERE 50-55
MOST LIKELY.

PREVIOUS DISCUSSION 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 /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 1255 PM EDT WEDNESDAY...

WIDESPREAD VFR CONDITIONS UNDER MAINLY CLEAR SKIES WILL PREVAIL
DURING THE NEXT 24 HOURS INTO THURSDAY AFTERNOON. GUSTY NW WINDS
WILL CONTINUE THIS AFTERNOON...WITH SUSTAINED 12-17 KTS INCLUDING
GUSTS TO 20-25 KTS. WINDS WILL DIMINISH AND BECOME LIGHT TONIGHT
WITH RETURN OF LIGHT SOUTH TO SOUTHWESTERLY FLOW THURSDAY AS HIGH
PRESSURE PASSES OVERHEAD 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 ACROSS SUNDAY WITH FAIR DRY WEATHER. MOISTURE
WILL START TO RETURN NORTH SUNDAY NIGHT AS A BOUNDARY LIFTS NE
AHEAD OF LOW PRESSURE ACROSS THE CENTRAL U.S. THIS WILL LIKELY
BRING SUB-VFR CONDITIONS LATER SUNDAY NIGHT AND ESPCLY ON MONDAY.
&&

.FIRE WEATHER...
AS OF 950 AM EDT WEDNESDAY...

RED FLAG WARNING IN EFFECT FROM THE VIRGINIA BLUE RIDGE NORTHWARD
INTO NORTH CENTRAL VA FOR STRONG NORTHWEST WINDS AND LOW HUMIDITY.
FIRE DANGER STATEMENT ELSW THIS AFTERNOON FOR INCREASED FIRE
DANGER WHERE WINDS WONT BE QUITE AS STRONG AND FUELS A BIT WETTER.
MOST CRITICAL AREA OUTSIDE THE RED FLAG HEADLINE WILL BE OVER THE
NW NC MOUNTAINS GIVEN THAT STRONGER WINDS ARE LIKELY TO PERSIST
WITH VERY LOW HUMIDITY. HOWEVER AFTER COORDINATION WITH NC
FORESTRY OFFICIALS WILL KEEP THE STATEMENT GOING GIVEN SLIGHTLY
HIGHER FUEL MOISTURE LEVELS IN THAT AREA.

OTRW WINDS WILL RANGE FROM 15 TO 20 MPH SUSTAINED...WITH GUSTS OF
25 TO 30 MPH THROUGH THIS AFTERNOON. HUMIDITY MINIMUMS NEAR 20
PERCENT WILL ALSO BE COMMON. IN ADDITION...IT HAS BEEN 7 DAYS
SINCE MEASURABLE RAINFALL HAS OCCURRED IN ROANOKE VALLEY AND THE
IMMEDIATE BLUE RIDGE 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 DROPPING
TO AROUND 7 PERCENT OR LOWER.

CONCERN IS FOR RAPID FIRE SPREAD IF A WILDFIRE OCCURS.

&&

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

&&

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



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