Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 012101
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
401 PM EST SUN FEB 1 2015

.SYNOPSIS...
LOW PRESSURE CENTERED NEAR SPRINGFIELD ILLINOIS THIS EVENING WILL
MOVE EAST BE CENTERED NEAR PITTSBURGH BY DAYBREAK MONDAY BEFORE
MOVING OFF THE NEW ENGLAND COAST MONDAY AFTERNOON. A STRONG COLD
FRONT WILL TRAIL SOUTH FROM THE LOW...SWEEPING ACROSS THE OHIO AND
TENNESSEE VALLEYS TONIGHT...CROSSING THE APPALACHIANS MOUNTAINS
MONDAY MORNING. WIDESPREAD PRECIPITATION WILL ACCOMPANY THIS STORM
SYSTEM WITH SNOW NORTH OF INTERSTATE 70 AND RAIN TO THE SOUTH.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 330 PM EST SUNDAY...

AN AREA OF LOW PRESSURE OVER ILLINOIS WILL DEEPEN AS IT TRACKS EAST-
NORTHEAST INTO THE OHIO VALLEY THIS EVENING. ONCE THIS SYSTEM ENTERS
THE OHIO VALLEY LIGHT RAIN WILL BEGIN TO OVERSPREAD THE FORECAST
AREA OVERNIGHT. LOW LEVELS HAVE BEEN SLOW TO SATURATE TODAY WITH DEW
POINTS STILL IN THE TEENS TO LOWER 20S AT 300 PM. SINCE MODELS ARE
RUNNING FAST WITH RAIN THIS AFTERNOON AND TO ACCOUNT FOR DRY LOW
LEVELS...WILL SLOW DOWN THE ARRIVAL OF PRECIPITATION UNTIL THIS
EVENING. REST ASSURE...IT WILL RAIN TONIGHT INTO MONDAY MORNING WITH
TOTALS RANGING FROM A HALF /0.50/ TO THREE-QUARTERS /0.75/ OF AN
INCH.

THE SURFACE LOW TRACKS INTO WESTERN PENNSYLVANIA MONDAY MORNING WITH
THE COLD FRONT JUST ENTERING THE WESTERN APPALACHIANS AROUND SUNRISE.
BY EARLY AFTERNOON...THE COLD FRONT IS ACROSS THE COASTAL PIEDMONT
WITH THE SURFACE LOW OFF THE NEW JERSEY SHORE. COLD AIR WILL BEGIN
TO ENTER THE AREA IN THE MORNING WITH HIGHER ELEVATIONS
TRANSITIONING TO SNOW EARLY. BY THE TIME THE COLDER AIR ARRIVES IN
NORTHWEST FLOW...BULK OF THE MOISTURE IS OUT OF THE AREA. WESTERN
SLOPES COULD SEE 2-3 INCHES ACROSS WESTERN GREENBRIER TO UP TO 2
INCHES ALONG WESTERN GRAYSON TO WESTERN WATAUGA. HIGH PRESSURE MOVES
OVER THE OHIO VALLEY QUICKLY AND UPSLOPE SNOW SHOWERS MAY NOT LAST
TO LONG INTO THE EVENING.

QUICK PRESSURE RISES BEHIND THE FRONT WILL BRING WINDY AND GUSTY
CONDITIONS TO THE AREA MONDAY INTO MONDAY EVENING. MODELS HAVE
BACKED OFF ON THE STRENGTH OF THE LOW LEVEL JET...THEREFORE WILL
ONLY CARRY AN ADVISORY FOR COUNTIES ALONG AND WEST OF THE BLUE RIDGE
TO INCLUDE THE SOUTHWESTERN VIRGINIA FOOTHILLS FOR GUST OF 40 TO 50
MPH. ALONG WITH THE STRONG NORTHWEST WINDS...TEMPERATURES WILL BE
FALLING...ESPECIALLY ACROSS THE MOUNTAINS THROUGH THE DAY MONDAY.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 315 PM EST SUNDAY...

500MB HEIGHTS RISE ON MONDAY NIGHT. ZONAL PATTERN ON TUESDAY WITH A
NORTHERN STREAM SHORT WAVE CROSSING THE OHIO VALLEY AND MID ATLANTIC
STATES. THE -5 TO -15 850 MB AIR THAT WAS OVER THE NORTHERN PLAINS
REACHES THE FORECAST AREA ON MONDAY NIGHT. 850MB TEMPERATURES
MODERATE TUESDAY AND TUESDAY NIGHT AND BY WEDNESDAY AREA AROUND
ZERO.

STARTING OFF MONDAY NIGHT WITH STRONG PRESSURE RISES. BUFKIT
FORECAST DOES NOT HAVE WIND GUSTS DROPPING BELOW 20 MPH UNTIL AFTER
MIDNIGHT ON MONDAY NIGHT. DEEP MOISTURE WILL BE WELL TO THE EAST ON
MONDAY NIGHT WITH REMAINING MOISTURE CONFINED TO BELOW 800MB.
UPSLOPE SNOW SHOWERS WILL BE ENDING DURING THE EVENING BUT THE
CLOUD COVER MAY LINGER THROUGH TUESDAY MORNING.

SURFACE HIGH PRESSURE MOVES IN TO THE FORECAST AREA ON TUESDAY THEN
OFFSHORE TUESDAY NIGHT. NOT MUCH SURFACE REFLECTION WITH THE SHORT
WAVE COMING THROUGH ON TUESDAY. ARCTIC COLD FRONT PASSES THROUGH
REGION ON WEDNESDAY NIGHT. LOW CLOUDS FILL IN BEHIND THE FRONT ON
WEDNESDAY NIGHT WITH AN INCREASING CHANCE OF UPSLOPE SNOW SHOWERS BY
THURSDAY MORNING WITH THE LOW LEVEL JET BECOMING STRONGER OUT OF THE
NORTHWEST.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 300 PM EST SUNDAY...

LATEST WEATHER FORECAST MODELS ARE IN SLIGHTLY BETTER AGREEMENT
CONCERNING DEVELOPMENT OF A COASTAL LOW ON THURSDAY...AND HOW IT
WILL AFFECT OUR WEATHER. EXPECT TO START THE DAY WITH A COLD FRONT
MAKING ITS WAY ACROSS THE PIEDMONT...WITH LIGHT UPSLOPE SNOW SHOWER
ACTIVITY ALONG THE WESTERN RIDGES...AND PERHAPS A FEW SNOW SHOWERS
ACROSS THE PIEDMONT IN THE VICINITY OF THE FRONT. PROGRESSING INTO
THE AFTERNOON...THE LOW WILL DRIFT NORTH...THOUGH FARTHER OFF THE
COAST THAN FORECAST MODELS WERE PREVIOUSLY CALLING FOR. WITH THE LOW
TRACKING FURTHER AWAY FROM OUR AREA...DO NOT SEE MOISTURE BEING
PUSHED AS FAR INLAND...AND THEREFORE EXPECT THE HIGHER PRECIPITATION
AMOUNTS TO BE CONFINED MORE TO THE COAST. MODELS AGREE THAT
ATMOSPHERIC TEMPERATURES ARE COLD ENOUGH THAT ANY PRECIPITATION WILL
REMAIN EXCLUSIVELY SNOW AS NORTHERLY WINDS DRAW SUB FREEZING AIR
FROM THE GREAT LAKES REGION.

RIGHT NOW...HAVE ONLY MODERATE CONFIDENCE IN THIS FORECAST. THE
WEATHER FORECAST MODELS HAVE HAD NOT ONLY SIGNIFICANT DIFFERENCES
WITH ONE ANOTHER CONCERNING THE TRACK AND THE IMPACTS OF THE
LOW...THEY HAVE ALSO BEEN FLIP FLOPPING FROM THEIR PREVIOUS RUNS AS
TO HOW THE LOW WILL BEHAVE. SO WILL STILL NOT HAZARD A GUESS AS TO
HOW MUCH SNOW WE CAN EXPECT...EXCEPT TO SAY THAT THE WORST CASE
SCENARIO PUTS ACCUMULATIONS AROUND THE LOW END OF ADVISORY CRITERIA.

WITH THE DEPARTURE OF THE LOW OUT TO SEA THURSDAY EVENING...HIGH
PRESSURE ACROSS THE SOUTHERN GREAT LAKES WILL BECOME OUR DOMINANT
WEATHER FEATURE. THE HIGH WILL SHIFT ACROSS OUR AREA ON THURSDAY
NIGHT AND FRIDAY...RESULTING IN TEMPERATURES IN THE TEENS AND SINGLE
DIGITS TO START THE DAY. THE HIGH WILL THEN SETTLE ALONG THE
ATLANTIC COAST FRIDAY NIGHT INTO SATURDAY...ALLOWING SOUTHWESTERLY
WINDS TO TAKE OVER FOR OUR AREA. THIS WILL RESULT IN A GRADUAL
WARMUP FOR THE WEEKEND...AHEAD OF OUR NEXT COLD FRONT APPROACHING
FROM THE NORTH.

&&

.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
AS OF 1230 PM EST SUNDAY...

VFR TODAY WILL DETERIORATE TO IFR AFTER SUNSET.

EXTENSIVE MID/UPPER LEVEL MOISTURE HAS BEEN CAST OVER THE CENTRAL
APPALACHIANS IN ADVANCE OF AN APPROACHING MID CONUS STORM.
PRECIPITATION FROM THESE HIGHER LEVEL CLOUDS IS EVAPORATING BEFORE
REACHING THE GROUND...WITH RADAR SHOWING VIRGA OVER THE ENTIRE AREA
INTO EARLY THIS AFTERNOON. HOLES IN A VFR STRATO-CUMULUS FIELD
EXPECTED THROUGH THE REST OF THE AFTERNOON...THEN WILL FILL BACK IN
AND CEILINGS LOWER AS PRECIPITATION SHIELD ENTERS FROM THE WEST LATE
THIS AFTERNOON/EARLY EVENING. FLIGHT CONDITIONS WILL DETERIORATE TO
MVFR BETWEEN 22Z/5PM AND 03Z/10PM THIS EVENING THEN TO IFR BETWEEN
03Z/10PM AND 07Z/2AM. CONDITIONS WILL THEN REMAIN IFR UNTIL A
FRONTAL PASSAGE MONDAY MORNING. STRONG SOUTHWEST WINDS ALOFT THIS
EVENING WILL RESULT IN WARMING TEMPERATURES. THIS WILL KEEP ALL OF
THE PRECIPITATION IN THE LIQUID FORM AS IT REACHES THE SURFACE
TONIGHT WITH NO P-TYPE ISSUES FOR ANY OF THE TERMINALS WITHIN THE
BLACKSBURG/ROANOKE SERVICE AREA.

LOW PRESSURE WILL BE CENTERED OVER PENNSYLVANIA EARLY MONDAY WITH
A COLD FRONT TRAILING SOUTH ALONG THE SPINE OF THE APPALACHIANS.
A SWEEPING COLD FRONT WILL CROSS ALL OF THE FLIGHT TERMINALS IN
THE CENTRAL APPALACHIANS EARLY IN THE DAY...WINDS SHIFTING TO THE
NORTHWEST AND BECOMING GUSTY FOR THE AFTERNOON. PASSAGE OF THE
FRONT WILL BRING AN END TO THE RAIN WITH IMPROVING CIGS/VSBYS.
THE MAIN WEATHER HAZARD WILL THEN BE THE 25 TO 40 KT WIND GUSTS.

EXTENDED DISCUSSION...
MONDAY NIGHT...SKIES CLEAR AND WINDS DIMINISH...RETURN OF VFR.

TUESDAY AND WEDNESDAY...HIGH PRESSURE PASSES OVERHEAD WITH VFR.

THURSDAY...LOW PRESSURE MOVING ACROSS THE SOUTHEAST U.S. MAY
BRING SUB-VFR CONDITIONS AND PRECIPITATION...POSSIBLY SNOW TO THE
REGION. SINCE THIS STORM IS TAKING A GULF COAST TRACK...WINTRY
PRECIPITATION MAY IMPACT SOUTHERN TERMINAL ROUTES INCLUDING
CHARLOTTE AND ATLANTA.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WIND ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT EST MONDAY
     NIGHT FOR VAZ009>020-022>024-032>035.
NC...WIND ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT EST MONDAY
     NIGHT FOR NCZ001-002-018.
WV...NONE.

&&

$$
SYNOPSIS...RCS
NEAR TERM...RCS
SHORT TERM...AMS
LONG TERM...NF
AVIATION...RCS


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