Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 302012
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
312 PM EST FRI JAN 30 2015

.SYNOPSIS...
COLD HIGH PRESSURE WILL GRADUALLY BUILD EAST INTO THE AREA TONIGHT
AND ABOUT OVERHEAD ON SATURDAY. THIS WILL ALLOW FOR DRIER WEATHER
UNDER DIMINISHING WINDS LATER TONIGHT INTO SATURDAY. ANOTHER AREA
OF LOW PRESSURE WILL MOVE OUT OF THE SOUTHWESTERN UNITED STATES ON
SATURDAY...CROSSING THE CENTRAL PART OF THE NATION SUNDAY...AND
REACHING THE EAST COAST BY MONDAY MORNING.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 215 PM EST FRIDAY...

FINAL WAVE ALOFT WITHIN THE BASE OF THE 5H TROUGH WILL PIVOT EAST OF
THE REGION THIS EVENING ALLOWING FOR A QUICK DECREASE IN MOISTURE AS
BETTER SUBSIDENCE ARRIVES AHEAD OF HIGH PRESSURE TO THE WEST. THIS
SHOULD BRING AN END TO MOST ACCUMULATING UPSLOPE SNOW ACROSS THE FAR
NW EARLY ON ESPCLY GIVEN THE PASSING OF THE COLDEST AIR AT 85H AND
SOME GRADUAL DECREASE IN THE JET ALOFT THROUGH MIDNIGHT. HOWEVER
WILL LIKELY STILL SEE SOME SNOW SHOWERS OR FLURRIES GIVEN LINGERING
LOW LEVEL MOISTURE SO KEEPING SO LOW POPS OR FLURRY MENTION GOING NW
THIRD THROUGH ABOUT MIDNIGHT FOR NOW. OTHERWISE APPEARS THE
STRONGEST OF THE SURFACE WINDS WILL EXIT AFTER DARK WITH PERHAPS A
SECOND SURGE ACROSS THE NORTH CAROLINA MOUNTAINS THIS EVENING BEFORE
SPEEDS DROP BELOW CRITERIA OVERNIGHT. HOWEVER STILL GUSTY ON THE
RIDGES GIVEN THE SLOWNESS OF THE SURFACE HIGH TO SHIFT EAST AND THE
FORECAST REMAINING PRESSURE GRADIENT OFF MOST MODELS. SHOULD FINALLY
SEE SKIES CLEAR FROM THE BLUE RIDGE EAST THIS EVENING AND ALL EXCEPT
THE FAR NW SLOPES LATE GIVEN LINGERING MOISTURE OFF THE NAM. EXPECT
ENOUGH COLD ADVECTION TO CAUSE TEMPS TO FALL INTO THE TEENS WITH A
FEW SINGLE DIGITS MOUNTAINS...AND UPPER TEENS TO LOW 20S EAST
DESPITE CONTINUED MIXING FOR MUCH OF THE AREA. THIS MAY BRING A FEW
AREAS INCLUDING THE HIGHER ELEVATIONS OF GREENBRIER AND BATH INTO
WIND CHILL ADVISORY CRITERIA BY MORNING.

SURFACE HIGH BUILDS OVERHEAD SATURDAY UNDER DEVELOPING ZONAL FLOW
ALOFT ALLOWING FOR LIGHTER WINDS AND WARMER TEMPS GIVEN 85H WARMING.
SOME INCREASE IN WARM ADVECTION MID/HIGH CLOUDS LIKELY BY MID/LATE
AFTERNOON UNDER THE FAST FLOW ALOFT FROM THE WEST BUT OVERALL
MOSTLY SUNNY. WITH WEAK DOWNSLOPE/DRY AIR...WENT ON THE WARMER
SIDE OF MOST ESPCLY EAST WHERE LOW/MID 40S LIKELY WHILE KEEPING THE
WEST MAINLY 30S TO AROUND 40 GIVEN THE 85H NW TRAJECTORY.
&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 240 PM EST FRIDAY...

A LARGE AREA OF HIGH PRESSURE WILL MOVE SOUTH ACROSS THE REGION
SATURDAY AND BE CENTERED NEAR THE SOUTH CAROLINA COAST SUNDAY
MORNING. THIS HIGH PRESSURE WILL STILL HAVE AN INFLUENCE ON OUR
WEATHER KEEPING DRY AIR...DEW POINTS IN THE TEENS...IN THE REGION. A
WARM FRONT ALOFT WILL TRACK ACROSS THE OHIO VALLEY EARLY SUNDAY
MORNING. ISENTROPIC LIFT MAY GENERATE PRECIPITATION ACROSS THE
GREENBRIER VALLEY TO THE ALLEGHANY HIGHLANDS SUNDAY MORNING AS THIS
WARM FRONT TRACKS NORTH TO THE MASON-DIXON LINE DURING THE DAY
SUNDAY. ANY PRECIPITATION FALLING INTO THIS DRY AIR WILL KEEP THE
AIR COLUMN COLD ENOUGH FOR LIGHT SNOW TO FALL IN THE MORNING. THIS
PRECIPITATION WILL MOVE NORTH OF THE AREA BY NOON. THE ENTIRE AREA
WILL BE IN THE WARM SECTOR SUNDAY AFTERNOON WITH TEMPERATURES
WARMING INTO THE 40S WEST AND LOWER 50S EAST.

ALSO ON SUNDAY...A NORTHERN STREAM TROUGH WILL COME OUT OF THE
ROCKIES SPAWNING A SURFACE LOW OVER THE RED RIVER VALLEY. THIS LOW
WILL THEN TRACK TO THE OZARKS SUNDAY MORNING...THEN OVER THE
SOUTHERN OHIO VALLEY IN THE AFTERNOON. THE CURRENT TRACK OF THIS LOW
WILL KEEP THE AREA IN A WARM AIRMASS THROUGH THE DAY SUNDAY. SHORT
WAVES AND SOUTHEAST FLOW WILL BRING LIGHT SHOWERS INTO THE AREA
DURING THE AFTERNOON. PRECIPITATION FALLING IN THE AFTERNOON SHOULD
KEEP TEMPERATURES MILD WHILE DEW POINTS AND WET BULB INCREASE INTO
THE 30S. DEPENDING ON HOW FAST PRECIPITATION MOVES INTO THIS DRY AIR
...IT MAY START OUT AS A BRIEF PERIOD OF A SNOW/SLEET MIX...BUT WILL
TRANSITION OVER TO A COLD RAIN.

MODELS CONTINUE TO TRACK THE SURFACE LOW NORTH OF THE AREA AND
ACROSS NORTHERN VIRGINIA/MARYLAND SUNDAY NIGHT. SOUTHERLY FLOW WILL
CONTINUE TO BRING WARM AIR INTO THE REGION WITH 85H TEMPERATURES 4C
OR WARMER. THE COLD FRONT DOES NOT ENTER RNK MOUNTAIN COUNTIES UNTIL
EARLY MONDAY MORNING. THEREFORE WILL DELAY CHANGE-OVER TO SNOW UNTIL
AFTER MIDNIGHT ACROSS SOUTHEASTERN WEST VIRGINIA. THE SURFACE LOW
TRACKS OFF THE MID ATLANTIC COAST MONDAY MORNING WITH PRECIPITATION
ENDING OVER THE PIEDMONT BY NOON. THE UPPER LEVEL PORTION OF THIS
SYSTEM WILL TRACK OVER THE FORECAST AREA DURING THE AFTERNOON. THE
DEFORMATION ZONE AND BRIEF UPSLOPE WILL BRING SCATTERED SNOW SHOWERS
TO THE MOUNTAINS THROUGH THE AFTERNOON...THEN HIGH PRESSURE MOVES
OVER THE OHIO VALLEY SHUTTING OFF MOISTURE FEED.

FOLLOWING THE FRONT...A SURGE OF ARCTIC AIR WILL SEND TEMPERATURES
DOWN THROUGH THE DAY MONDAY. MORNING HIGHS IN THE 30F-35F RANGE IN
THE WEST TO A LATE MORNING MAX IN THE EAST IN THE M/U 40S. ALSO
BEHIND THE FRONT...STRONG PRESSURE RISES AND COLD AIR ADVECTION WILL
BRING HIGH WINDS AND GUSTY CONDITIONS TO THE AREA. ONLY THING
LACKING FOR A HIGH CONFIDENCE HIND WIND WATCH/WARNING IS A STRONG
LOW LEVEL JET. MODELS ARE ONLY DISPLAYING A 40KT JET OVER THE BLUE
RIDGE WITH HIGHER SPEEDS TO THE NORTH.
&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 330 PM EST THURSDAY...

TEMPERATURES BELOW NORMAL THROUGH THE EXTENDED...TRENDING TO MUCH
BELOW NORMAL TOWARD THE END OF NEXT WEEK.

MODELS KEEP THINGS PROGRESSIVE AND ARE CONSISTENT IN PHASING THE
UPPER LEVEL SPLIT FLOW PATTERN INTO A LONG WAVE WESTERN
TROF/EASTERN RIDGE PATTERN. THIS WILL OPEN THE DOOR FOR A SHOT OF
ARCTIC AIR AS WE GET TOWARD THE END OF THE PERIOD.

WE START THE PERIOD WITH A COASTAL LOW OFF THE MIDDLE ATLANTIC
COAST PULLING AWAY FROM THE REGION...LEAVING US WITH COLDER AIR
MOVING IN AND RESIDUAL NORTHWEST UPSLOPE FLOW SNOW SHOWERS WEST OF
THE BLUE RIDGE. THE SNOW SHOWERS COME TO AN END MONDAY NIGHT AS
HIGH PRESSURE BUILDS IN FROM THE OHIO VALLEY AND BRINGS US QUIET
AND COLD WEATHER FOR TUESDAY AND TUESDAY NIGHT.

THE NEXT CHANCE FOR PRECIPITATION COMES ON WEDNESDAY AS DEEPENING
LOW PRESSURE SYSTEM IS DRIVEN BY A VIGOROUS SHOT WAVE THROUGH THE
GREAT LAKES REGION AND INTO CANADA. THIS WILL SWING A COLD FRONT
THROUGH THE REGION...OPENS THE DOOR TO ARCTIC HIGH PRESSURE
BUILDING IN FROM THE MIDWEST. MODEL RUN TO RUN VARIABILITY IN THE
EXTENDED HAS BEEN QUITE HIGH RECENTLY AND WHILE EVOLUTION OF THE
OVERALL SYNOPTIC PATTERN SEEMS SOLID...DO NOT HAVE A LOT OF
CONFIDENCE IN SPECIFICS FROM ANY OF THE INDIVIDUAL SOLUTIONS. THE
EURO IS QUITE AGGRESSIVE IN DIGGING THE EASTERN TROF AND DEVELOPS
A COASTAL LOW MOVING OUT OF THE GULF WITH A CHANCE OF WINTRY
PRECIPITATION FOR OUR NORTH AND WEST AREAS...WHILE THE GFS/NAEFS
IS LESS AMPLIFIED AND DOES NOT ADVERTISE A COASTAL LOW AND KEEPS
US MOSTLY DRY. WILL HAVE TO WAIT AND SEE HOW THIS ALL PLAYS OUT IN
LATER MODEL RUNS BUT FOR NOW WILL SHADE THE FORECAST TOWARD THE
DRIER GFS/NAEFS.
&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
AS OF 1210 PM EST FRIDAY...

MAIN CONCERN CONTINUES WITH STRONG NORTHWEST WINDS THIS AFTERNOON
AND EVENING. WITH A 50KT NORTHWESTERLY JET ALOFT OVER THE
REGION... EXPECT 25-40KT SURFACE WIND GUSTS...ESPECIALLY THIS
AFTERNOON. WINDS WILL DIMINISH SOMEWHAT AFTER SUNSET...BUT WILL
NOT COMPLETELY DIMINISH UNTIL HIGH PRESSURE MOVES OVERHEAD
SATURDAY.

MOUNTAIN SNOW SHOWERS WILL PERSIST AS WELL INTO LATE THIS
AFTERNOON WITH MVFR/OCNL IFR LIKELY ACROSS THE
MOUNTAINS...IMPACTING KBLF/KLWB/KBCB. FLURRIES MAY DRIFT AS FAR
EAST AS THE BLUE RIDGE...BUT OVERALL VFR WITH LATE AFTERNOON
CLEARING IS EXPECTED EAST OF THE BLUE RIDGE PER STRONG SUBSIDENCE
AND DRYING.

WINDS WILL DIMINISH FOR SATURDAY AS HIGH PRESSURE MOVES INTO THE
REGION FROM THE WEST. ANY REMAINING LOW CLOUDS LINGERING ACROSS
EASTERN WEST VA SHOULD DISSIPATE...WITH MAINLY VFR REGION WIDE
FOR SATURDAY.

EXTENDED DISCUSSION...

THE NEXT LOW PRESSURE SYSTEM HEADING OUT OF THE SW STATES WILL
BRING A RETURN OF CLOUDS AND PRECIPITATION ON SUNDAY WITH
WIDESPREAD MVFR TO IFR CIGS/VSBYS LIKELY WITHIN THIS TIME FRAME.
THE NORTHERN SECTIONS OF THE CWA WILL LIKELY SEE SOME WINTER
PRECIPITATION WITH THIS EVENT...WHILE THE SOUTHERN AREAS SHOULD
SEE MOSTLY RAIN. IN BETWEEN...LOCATIONS SUCH AS
KBCB/KROA/KLYH...COULD SEE A BRIEF MIX OF RAIN AND SNOW AT THE
ONSET WITH MOSTLY A RAIN EVENT OVERALL. MOUNTAIN SNOW SHOWERS WITH
MVFR CIGS/VSBYS WILL CONTINUE INTO MONDAY...WITH STRONG AND GUSTY
WINDS ALL AREAS BY MONDAY AFTERNOON. IMPROVING CONDITIONS ARE
EXPECTED BY TUESDAY WITH VFR RETURNING FOR ALL LOCATIONS UNDER
HIGH PRESSURE.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WIND ADVISORY UNTIL 9 PM EST THIS EVENING FOR VAZ009>014-
     016>020-022>024-032>035.
     WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR VAZ015.
     WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EST SATURDAY
     FOR VAZ020.
NC...WIND ADVISORY UNTIL 9 PM EST THIS EVENING FOR NCZ002.
     WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NCZ001-018.
WV...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EST SATURDAY
     FOR WVZ507-508.

&&

$$
SYNOPSIS...JH/PM
NEAR TERM...JH
SHORT TERM...RCS
LONG TERM...MBS
AVIATION...JH/PM


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