Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 291001
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
501 AM EST THU JAN 29 2015

.SYNOPSIS...

LOW PRESSURE NEAR CHICAGO THIS MORNING WILL MOVE RAPIDLY EAST ACROSS
SOUTHERN MICHIGAN TODAY AND INTO NEW ENGLAND TONIGHT.  A SURFACE
COLD FRONT WILL TRAIL SOUTH FROM THE LOW...AND WILL SWEEP SOUTHEAST
ACROSS THE OHIO VALLEY TODAY...THEN THROUGH THE MID ATLANTIC REGION
TONIGHT. HIGH PRESSURE WILL THEN BUILD ACROSS THE REGION FOR FRIDAY
AND SATURDAY...FOLLOWED BY AN AREA OF LOW PRESSURE WHICH WILL MOVE
FROM TEXAS SUNDAY...TO THE MID ATLANTIC COAST BY MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 430 AM EST THURSDAY...

ANOTHER COLD START WITH TEMPERATURES IN THE 20S THIS MORNING. A FEW
LOCATIONS DIPPED INTO THE TEENS DURING THE NIGHT BUT INCREASING
CLOUD COVER HAS PUT A HALT TO THE FALLING TEMPERATURES. IN SPITE OF
THE INCREASING UPPER LEVEL CLOUD COVER...THE BOUNDARY LAYER REMAINS
VERY DRY WITH DEWPOINTS IN THE TEENS AND SINGLE DIGITS.

FOR TODAY...WATCHING AN AREA OF LOW PRESSURE VCNTY OF CHICAGO. THIS
CLIPPER LIKE SYSTEM WILL MOVE RAPIDLY EAST TODAY...REACHING BUFFALO
NEW YOUR BY THIS EVENING.  A COLD FRONT TRAILS SOUTH FROM THE LOW
AND IS ASSOCIATED WITH A NARROW CORRIDOR OF LOW LEVEL MOISTURE WHICH
IS RESULTING IN SOME LIGHT PRECIPITATION FROM INDIANA TO WESTERN KY.
SURFACE OBS INDICATE MOST OF THIS PRECIP TO BE LIGHT RAIN OR VIRGA
YIELDING TRACE AMOUNTS TO AS MUCH AS 2 HUNDREDTHS OF AN INCH /0.02/.
THIS BAND OF LIGHT PRECIPITATION IS FORECAST TO PROGRESS EAST THIS
MORNING...CROSSING OHIO AND KENTUCKY.

MODELS INDICATE THE LEADING EDGE OF THE PRECIPITATION WILL REACH OUR
FAR WESTERN CWA AROUND 18Z/1PM TODAY...THEN DRY UP AS IT ENCOUNTERS
THE VERY DRY BOUNDARY LAYER AIR ON THE EAST SIDE OF THE MOUNTAINS
THIS AFTERNOON.  THIS SEEMS REASONABLE...AND HAVE PRETTY MUCH
FOLLOWED GUIDANCE WITH RESPECT TO POPS CONFINING THE HIGHEST POPS
AND BEST CHANCE FOR MEASURABLE PRECIPITATION TO OUR WESTERN
COUNTIES...WITH ONLY A SLIGHT CHANCE ANYTHING MAKES IT EAST OF THE
MOUNTAINS THIS AFTERNOON. AS FAR AS P-TYPE...IT LOOKS LIKE THE
BOUNDARY LAYER WILL BE TOO WARM TO SUPPORT SNOW... SO WILL GO WITH
MAINLY RAIN OR SPRINKLES. SINCE THE BOUNDARY LAYER IS SO DRY AND
THE WETBULB WILL BE NEAR FREEZING...CAN`T RULE OUT SOME SLEET
MIXING IN AT THE ONSET. BEST CHANCE FOR SEEING SLEET WOULD BE
ALONG AND NORTH OF INTERSTATE 64. WITH TEMPERATURES CLIMBING ABOVE
FREEZING THIS SHOULD HAVE NO IMPACT...AT LEAST DURING THE DAY
LIGHT HOURS.

FOR TONIGHT...PASSAGE OF THE COLD FRONT DURING THE EVENING WILL
BRING FALLING TEMPERATURES.  ANY LINGERING MOISTURE WILL THEN CHANGE
BACK OVER TO SNOW.  MAIN FOCUS FOR SNOW WILL BE OVER THE WESTERN CWA
WHERE PERSISTENT LOW LEVEL MOISTURE WILL REMAIN ON THE WESTERN
SLOPES OF THE APPALACHIANS...YIELDING OCCASIONAL SNOW SHOWERS AND
FLURRIES. HIGHEST ACCUMULATIONS ARE EXPECTED TO BE OVER THE WV
HIGHLANDS... WITH 2 TO 4 INCHES POSSIBLE FOR WESTERN GREENBRIER.
AN INCH OR TWO IS ALSO POSSIBLE FROM BLUEFIELD SOUTHWARD INTO THE
NORTH CAROLINA HIGH COUNTRY...BUT AGAIN...FOCUS FOR THE GREATEST
ACCUMULATIONS WILL BE ACROSS THE HIGHER TERRAIN. ON THE EAST SIDE
OF THE MOUNTAINS... DOWNSLOPE FLOW WILL RESULT IN DRYING...WITH
LITTLE OR NO PRECIP. A FEW FLURRIES MAY BE ENCOUNTERED AS FAR EAST
AS THE BLUE RIDGE.

IT WILL BECOME BREEZY THIS AFTERNOON AHEAD OF THE FRONT...SOUTHWEST
WINDS INCREASING TO 10 TO 15 MPH. PASSAGE OF THE FRONT WILL BRING
A WIND SHIFT TO THE WEST...THEN TRENDING MORE TO THE NORTHWEST
LATE TONIGHT. THE INCREASING PRESSURE GRADIENT ASSOCIATED WITH THE
STRENGTHENING AREA OF LOW PRESSURE OVER NEW ENGLAND WILL RESULT IN
INCREASING WIND SPEEDS OVERNIGHT WITH SURFACE GUSTS APPROACHING 40
MPH ACROSS THE RIDGES BY DAYBREAK FRIDAY.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS OF 400 AM EST THURSDAY...

WINDY AND COLD IS ON THE WAY FOR FRIDAY AS A COLD FRONT PUSH OUT
INTO THE ATLANTIC OCEAN. SERIES OF SHORT WAVES SHARPENS UPPER TROF
WITH A 500MB LOW CLOSING OFF OVER LONG ISLAND BY LATE FRIDAY. THE
SECOND RE-ENFORCING SHOT OF MUCH COLDER 850MB AIR ARRIVES ON FRIDAY
WITH A PUNCH.  ALONG WITH THE COLD AIR ADVECTION...LOW LEVEL JET
COMES AROUND TO THE NORTHWEST STARTING LATE THURSDAY NIGHT WITH
SPEEDS OF AROUND 50 KNOTS INTO FRIDAY NIGHT. STRONG WINDS WILL BE
ALONG THE SOUTHERN APPALACHIANS FRIDAY...THEN ROTATE TO THE NORTHERN
APPALACHIANS ON FRIDAY NIGHT AS THE SURFACE LOW DEEPENS OFF THE NEW
ENGLAND COAST. 6 HOUR PRESSURE RISES...BUFKIT SOUNDINGS...AND LOW
LEVEL JET SUPPORT THE POTENTIAL FOR ADVISORY LEVEL WINDS ALONG THE
BLUE RIDGE BEHIND THE COLD FRONT FRIDAY INTO FRIDAY EVENING. WITH
TIMING BEING THE THIRD AND FOURTH PERIODS...THIS WIND THREAT WILL
REMAIN HIGHLIGHTED IN HAZARDOUS WEATHER OUTLOOK AS COORDINATED WITH
WBC AND GSP.

WITH THE STRONG NORTHWEST FLOW...SNOW SHOWERS AND SNOW FLURRIES WILL
CONTINUE FRIDAY IN THE WEST ESPECIALLY DURING THE MORNING. INCREASED
POPS ALONG THE WESTERN SLOPES IN GREENBRIER COUNTY FRIDAY MORNING.
CLEARING EXPECTED EAST OF THE BLUE RIDGE FRIDAY. THE REMAINING LOW
LEVEL MOISTURE ON THE WESTERN SLOPES ON FRIDAY ERODES AS THE DAY
PROGRESSES. USED A NON-DIURNAL TEMPERATURE CURVE FOR FRIDAY WITH
HIGHS FROM THE LOWER 20S IN THE NORTHWEST TO THE LOWER 40S IN THE
SOUTHEAST. HIGH PRESSURE SLOWLY BUILDS EAST INTO OUR AREA FRIDAY
NIGHT. LOW TEMPERATURES FRIDAY NIGHT INTO SATURDAY MORNING WILL
RANGE FROM THE SINGLE DIGITS IN THE MOUNTAINS TO THE LOWER 20S IN
THE PIEDMONT.

A WEAK SURFACE HIGH PRESSURE SLIDE SOUTHEAST SATURDAY. THIS WILL
ALLOW SURFACE AND LOW LEVEL WINDS TO DIMINISH AND BACK MORE TO THE
WEST. LOOK FOR INCREASING CLOUDS SATURDAY AS MOISTURE SPREAD EAST
FROM THE SOUTHERN PLAINS SYSTEM. HIGH TEMPERATURES SATURDAY WILL
RANGE FROM THE MID 20S IN THE NORTHWEST TO THE LOWER AND MID 40S IN
THE SOUTHEAST. WITH BOTH THE GFS AND ECMWF A LITTLE SLOWER WITH
MOISTURE...DECIDE TO HOLD BACK LIGHT POPS TO LATE SATURDAY NIGHT.
LOWS SATURDAY NIGHT WILL GENERALLY BE FROM AROUND 20 DEGREES TO
AROUND THE FREEZING MARK.

AS THE HIGH PRESSURE PUSHES TO OUR EAST AND WAVES OF LOW PRESSURE
RIDE ALONG AN APPROACHING COLD FRONT...EXPECT OUR CHANCES FOR
PRECIPITATION TO INCREASE FOR SUNDAY AND SUNDAY NIGHT. PTYPE WILL BE
WINTRY MIXTURE AT THE START THEN EXPECT A MOSTLY RAIN EVENT...THEN
BACK TO SOME UPSLOPE SNOW SHOWERS WEST OF THE BLUE RIDGE AS WE GET
ON THE BACK SIDE OF THE LOW INTO MONDAY. THE PLACEMENT OF THE LOW
CENTER AND ITS TRACK WHETHER SOUTH OR WEST OF US HAS BEEN
PROBLEMATIC FOR OUR FORECAST WITH MODEL DIFFERENCES.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 400 AM EST THURSDAY...

COLD HIGH PRESSURE THEN BUILDS AS UPSLOPE SNOW SHOWERS WIND DOWN
MONDAY INTO MONDAY NIGHT AND...AFTER A VERY COLD MORNING...QUIET
WEATHER SHOULD BE THE RULE FOR TUESDAY. HEADING INTO WEDNESDAY...THE
REMNANTS OF THE CLOSED UPPER LOW WILL BE EJECTING TOWARD US AS THE
NRN AND SRN STREAMS PHASE. LONG RANGE MODELS ARE INDICATING THE
POTENTIAL FOR A /MILLER A/ TYPE LOW TO DEVELOP OVER THE GULF COAST
WEDNESDAY AND TRACK THROUGH THE SOUTHEAST US AND OFF THE MIDDLE
ATLANTIC COAST WEDNESDAY NIGHT. TEMPERATURES ARE CURRENTLY EXPECTED
TO BE BORDERLINE AT BEST ACROSS OUR AREA FOR WINTRY WEATHER. NOTHING
TO GET EXCITED ABOUT AT THIS POINT...BUT WE WILL BE WATCHING TO SEE
HOW LATER MODEL RUNS HANDLE THE EVOLUTION OF THIS SYSTEM.

&&

.AVIATION /10Z THURSDAY THROUGH MONDAY/...
AS OF 430 AM EST THURSDAY...

HIGH CLOUDS WILL INCREASE FROM THE WEST THIS MORNING...MAINLY
ACROSS NORTHERN PORTIONS OF THE CWA...IN ADVANCE OF AN ALBERTA
CLIPPER...THE MAIN DYNAMICS OF WHICH WILL REMAIN NORTH OF OUR CWA.
ALL CLOUD BASES SHOULD REMAIN VFR THROUGH NOON TODAY. NOT
EXPECTING ANY PROBLEMS WITH VISIBILITY THIS MORNING AS THE SFC
AIR MASS IS VERY DRY.

BY THIS EVENING...THE CLIPPER WILL RACE ACROSS THE GREAT LAKES
INTO WESTERN NEW YORK/QUEBEC. A NARROW BAND OF PRECIPITATION
WILL ACCOMPANY THE COLD FRONT WHICH TRAILS SOUTH FROM THE AREA OF
LOW PRESSURE. THE MOISTURE IS EXPECTED TO DRY UP AS IT CROSSES THE
MOUNTAINS THIS AFTERNOON. SHOWERS WILL BE FOUND MAINLY NORTH OF
U.S. 460 AND WEST OF I-81...WITH ONLY SPRINKLES EXPECTED TO THE
SOUTH AND EAST. PRECIPITATION WILL BE FALLING FROM MID-BASED
CLOUDS AND LIGHT...SO VISIBILITY WILL NOT BE AN ISSUE...EXCEPT
POSSIBLY AT BLF/LWB WHERE DYNAMICS/LIFT ARE BETTER AND CLOUD CIGS
COULD LOWER TO LOW END VFR OR HIGH END MVFR DURING THIS
ACTIVITY...POTENTIALLY REDUCING VSBY THEN TO MVFR CATEGORY IN
-SHRA. SFC/850MB TEMPS SHOULD REMAIN WARM ENOUGH FOR ALL LIQUID
THROUGH 00Z/7PM THIS EVENING.

BEHIND THE COLD FRONT...ROUGHLY FROM 02Z/9PM FAR WEST TO AFT
06Z/1AM FRIDAY FAR EASTERN PIEDMONT...THERE WILL BE AN INCREASING
THREAT FOR MOUNTAIN SNOW SHOWERS AND FLURRIES...INCLUDING
LWB/BLF. CIGS WILL ALSO DROP INTO THE MVFR RANGE AND VISIBILITY
POTENTIALLY INTO THE MVFR RANGE AT TIMES IN THE MOUNTAINS. EAST OF
THE MOUNTAINS...DOWNSLOPE DRYING WILL RESULT IN LESS CLOUD COVER
AND LITTLE OR NO PRECIP.

WINDS WILL BECOME THE MAIN CONCERN BY FRIDAY AS THE CLIPPER MOVES
EAST OF THE REGION AND VERY STRONG NORTHWEST WINDS DEVELOP IN ITS
WAKE. WINDS BY FRIDAY MORNING ARE EXPECTED TO BE OUT OF THE WNW
12-18KTS WITH GUSTS 25-30KTS THROUGHOUT THE DAY FRIDAY.

EXTENDED DISCUSSION...

MVFR CIGS MAY LINGER OVER THE MOUNTAINS INTO FRIDAY NIGHT WITH
STRONG NW WINDS...AFTER WHICH LOOK FOR IMPROVING CONDITIONS WITH
VFR EXPECTED SATURDAY AND SATURDAY NIGHT COURTESY OF HIGH PRESSURE
PASSING OVERHEAD THE FIRST HALF OF THE WEEKEND.

THE NEXT LOW PRESSURE SYSTEM HEADING OUT OF THE SW STATES WILL
BRING A RETURN OF CLOUDS AND SOME PRECIPITATION ON SUNDAY AND
MONDAY WITH WIDESPREAD MVFR TO IFR LIKELY.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO NOON EST
     FRIDAY FOR WVZ508.

&&

$$
SYNOPSIS...PM
NEAR TERM...PM
SHORT TERM...KK
LONG TERM...MBS
AVIATION...PM


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