-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 250438
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1138 PM EST TUE FEB 24 2015

.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL MOVE FROM THE GULF TOWARD THE
CAROLINA COAST LATE WEDNESDAY INTO THURSDAY BRINGING MORE
SNOWFALL FOR MUCH OF THE AREA...WITH THE HIGHEST AMOUNTS EXPECTED OVER
THE SOUTHERN COUNTIES. HIGH PRESSURE WITH MORE COLD AIR WILL
FOLLOW BEHIND THIS SYSTEM FOR LATE IN THE WEEK.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
-- Changed Discussion --
AS OF 1125 PM EST TUESDAY...

WE ARE SEEING LESS CLOUD COVER NOW THAT DRIER AIR HAS PUSHED
FURTHER IN FROM THE NORTH...BUT STILL SOME STRATUS/STRATOCU OVER
THE MTN EMPIRE AND EAST OF THE MOUNTAINS IN NC. WILL SEE THESE
WITHER AWAY OVERNIGHT WITH NEXT UPSTREAM CLOUDS ARRIVING TOWARD SE
WV BY 4 AM WITH A FEW SNOW SHOWERS. NOT TOO MANY MAJOR
MODIFICATIONS WERE NEEDED TO THE FORECAST OVERNIGHT.

PREVIOUS VALID DISCUSSION...

LOW TEMPERATURES WILL BE MILDER THAN THOSE OF THIS MORNING...BUT
WE WILL STILL STAY ON THE LOW SIDE OF GUIDANCE...IF NOT SLIGHTLY
LOWER THAN GUIDANCE. A MIX OF UPPER TEENS TO LOW 20S ARE FORECAST
FOR THE MOUNTAINS WITH LOW TO MID 20S ACROSS THE PIEDMONT.

ON WEDNESDAY...THE UPSLOPE SNOW SHOWERS WILL DECREASE IN COVERAGE AS
850 MB WINDS SLOW AND BECOME SOUTHERLY BY THE AFTERNOON. CLOUD COVER
WILL INCREASE IN ADVANCE OF LOW PRESSURE MOVING THROUGH THE GULF
COAST STATES. OVERRIDING PRECIPITATION FROM THIS SYSTEM MAY REACH
THE FAR SOUTHWEST PART OF THE FORECAST AREA LATE IN THE DAY. WILL
CONTINUE WITH A MENTION OF A SLIGHT CHANCE OF SNOW ACROSS THE
NORTHERN MOUNTAINS OF NORTH CAROLINA AND NEIGHBORING FOOTHILLS. HIGH
TEMPERATURES WILL RANGE FROM THE LOW TO MID 30S ACROSS THE MOUNTAINS
AND UPPER 30S TO LOWER 40S ACROSS THE PIEDMONT.
-- End Changed Discussion --

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
-- Changed Discussion --
AS OF 1125 PM EST TUESDAY...

BASED ON THE TRENDS IN THE 21Z SREF/00Z NAM...REGARDING QPF AND
THE MEAN OF THE SREF SHOWING A DEFINITE THREAT OF WARNING SNOW
WENT AHEAD OF UPGRADED THE WATCH TO A WARNING FOR HEAVY SNOW FOR
THE NC MTNS/FOOTHILLS...NORTH TO GRAYSON/CARROLL/PATRICK. THIS IS
MAINLY DUE TO AN ARRIVAL TIME SHORTLY AFTER DUSK WED
EVENING...WITH HEAVIER SNOW ARRIVING PRIOR TO MIDNIGHT. PER
COORDINATION WITH OTHER OFFICES WILL LEAVE OUR EASTERN EXTENT OF
THE WATCH WILL REMAIN IN A WATCH AS WELL AS SMYTH/WYTHE. THINK
THE NC PIEDMONT AND SOUTHSIDE VA NORTHWEST TOWARD
FLOYD/FRANKLIN/HENRY WILL LIKELY GET WARNING AMOUNTS BUT ITS
TOO CLOSE. REST OF THE FORECAST WILL LIKELY BE IN ADVISORY LEVEL
AMOUNTS.

PREVIOUS DISCUSSION AT 645 PM...

18Z NAM/GFS...12Z ECMWF STILL ARE KEEPING A SHARP ENOUGH GRADIENT
TO THE TOTAL QPF FOR THIS WINTER EVENT WED EVENING THROUGH
THURSDAY SUCH THAT CONFIDENCE IS BORDERLINE ON WATCH VS WARNING
IN SOUTHSIDE VA/NW NC. WILL TAKE A GANDER AT THE 21Z SREF THEN
SOME 00Z MODELS BEFORE DECIDING ON WHETHER TO UPGRADE WATCH TO A
WARNING. THE 15Z SREF DOES SHOW PROBABILITY OF 4" OR GREATER
SNOWFALL BEING OVER 60 PERCENT OR MORE IN THE SOUTHSIDE VA
PIEDMONT INTO THE NC PIEDMONT...WHICH IN 12 HRS FITS WARNING
CRITERIA. FOR NOW WILL KEEP THE WATCH IN PLACE AS IS.

PREVIOUS DISCUSSION AT 345 PM...
WILL BE DEALING WITH IMPENDING SOUTHERN STREAM SYSTEM FROM LATE
WEDNESDAY THROUGH A GOOD PART OF THURSDAY. PLENTY OF UNCERTAINTY
EXISTS AMONG VARIOUS MODELS WITH SREF/NAM CONSIDERABLY MORE
BULLISH ON QPF/SNOW THAN GLOBAL MODELS WHICH ARE CONSISTENTLY LESS
AGGRESSIVE WITH THIS SYSTEM. ONE THING THAT DOES APPEAR CERTAIN IS
P- TYPE WITH ALL THICKNESS PARAMETERS AND H85 TEMPS SUFFICIENTLY
COLD FOR ALL SNOW EVEN ACROSS PIEDMONT. HENCE IT BECOMES A QPF
FORECAST AND AT THIS POINT WE HAVE QPF RANGING FROM LESS THAN 0.10
INCHES NORTH OF ABOUT ROANOKE WITH INCREASING AMOUNTS SOUTHWARD
REACHING ABOUT CLOSE TO 0.50 INCHES IN SOUTHERN PARTS OF OUR NORTH
CAROLINA COUNTIES. THE TENDENCY OF THE LAST SEVERAL SYSTEMS TO SEE
A LATE SHIFT NORTHWARD IN QPF HAS BEEN NOTED BY SEVERAL
FORECASTERS AND THAT POTENTIAL CANNOT BE RULED OUT FOR THIS STORM.
AT THIS POINT WILL GO WITH WINTER STORM WATCH INTO PARTS OF
SOUTHERN VIRGINIA WHERE CURRENT FORECAST QPF/SNOW DOES NOT SUGGEST
MEETING WINTER STORM CRITERIA BUT THIS ACCOUNTS FOR THE
UNCERTAINTY OF A NORTHWARD SHIFT IN THE TRACK AND HIGHER SNOWFALL.
FORECASTING CLOSE TO 6 INCHES OR POSSIBLY A LITTLE MORE IN FAR
SOUTHERN COUNTIES...WITH HIGHEST OVER THE MOUNTAINS...DIMINISHING
TO AROUND 3-5 INCHES ALONG THE NC/VA BORDER AND PERHAPS 2 TO 3
INCHES INTO THE NEW RIVER VALLEY AND INTO ROANOKE METRO AREA. SOME
UPSLOPE CAN BE EXPECTED IN THE USUAL AREAS AS MORE COLD AIR MOVES
IN BEHIND THIS LATEST WINTER STORM.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 355 PM EST TUESDAY...

LOOKING TO FRIDAY MORNING...MAY SEE A FEW LINGERING SNOW SHOWERS
ACROSS SOUTHEAST WEST VIRGINIA INTO THE NORTH CAROLINA HIGHLANDS AS
ANOTHER SHOT OF ARCTIC HIGH PRESSURE BUILDS EAST FROM THE CENTRAL
PLAINS...PUSHING TOWARD THE APPALACHIAN CHAIN THROUGH THE DAY. THE
APPROACH OF THE HIGH WILL GRADUALLY CAUSE WINDS TO SHIFT
NORTHEASTERLY...INCREASING THE FETCH OF COLD AIR FROM THE NORTH INTO
OUR AREA. AS SUCH...DO NOT EXPECT AFTERNOON HIGHS ACROSS THE
MOUNTAINS TO RISE ABOVE FREEZING...WHILE AREAS EAST OF THE BLUE
RIDGE WILL ONLY REACH INTO THE LOW TO MID 30S. HIGH PRESSURE WILL
REACH NEW ENGLAND FRIDAY EVENING...AND THEN BUILD SOUTH ACROSS THE
MID ATLANTIC FRIDAY NIGHT. FRIDAY NIGHT WILL BE ESPECIALLY FRIGID
DUE TO STRONG RADIATIONAL COOLING ASSOCIATED WITH MOSTLY CLEAR SKIES
AND LIGHT WINDS...WITH OVERNIGHT LOWS RANGING FROM NEAR ZERO ACROSS
SOUTHEAST WEST VIRGINIA...TO THE UPPER TEENS ACROSS THE SOUTHSIDE.

FOR SATURDAY...HIGH PRESSURE WEDGED AGAINST THE EASTERN FACE OF THE
APPALACHIANS WILL MAINTAIN CHILLY TEMPERATURES AREAWIDE...WITH
AFTERNOON HIGHS RANGING FROM THE UPPER 20S NORTH TO THE MID 30S
SOUTH. CLOUD COVER WILL INCREASE DURING THE EVENING HOWEVER...AS OUR
NEXT UPPER LEVEL DISTURBANCE APPROACHES FROM THE WEST...SO EXPECT
SATURDAY NIGHT LOWS TO HOLD IN THE TEENS AND LOW 20S.

THE CHANCE FOR SNOW WILL INCREASE TOWARD DAWN SUNDAY AS A WEAK LOW
PRESSURE SYSTEM PASSES UP THE ATLANTIC COAST...POTENTIALLY SPREADING
PRECIPITATION AS FAR WEST AS THE NEW RIVER VALLEY. WITH COLD HIGH
PRESSURE STILL IN PLACE ACROSS THE MID ATLANTIC...BELIEVE THE
WEATHER MODELS ARE CALLING FOR TEMPERATURES THAT ARE FAR TOO WARM...
AND THEREFORE WENT WITH HIGHS THAT ARE SEVERAL DEGREES COOLER. AS
SUCH...DO NOT HAVE MUCH CONFIDENCE IN WHAT TYPE OF PRECIPITATION TO
EXPECT...IF ANY. WILL JUST CONTINUE TO WATCH THE EVOLUTION OF THIS
SYSTEM OVER THE NEXT DAY OR TWO.

WITH THE PASSAGE OF THE COASTAL LOW PRESSURE SYSTEM...WINDS ACROSS
OUR AREA WILL SHIFT WESTERLY AND DOWNSLOPE...WHICH WILL ALLOW FOR
WARMER TEMPERATURES ON MONDAY. EARLY INDICATIONS ARE THAT HIGH
TEMPERATURES NEXT MONDAY WILL BE THE WARMEST IN OVER A WEEK...WITH
AFTERNOON TEMPERATURES RANGING FROM THE UPPER 40S ACROSS THE
MOUNTAINS...TO THE MID 50S ACROSS THE SOUTHSIDE. RAIN CHANCES WILL
INCREASE DURING THE AFTERNOON AS ANOTHER COLD FRONT APPROACHES FROM
THE WEST.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 630 PM EST TUESDAY...

MVFR CIGS WILL DIMINISH THIS EVENING OVER MOST OF THE AREA AS
DRIER MOVES IN BEHIND STORM SYSTEM OFF THE COAST. LOOKING AT VFR
THROUGH WEDNESDAY EXCEPT INCREASING MVFR CIGS TOWARD BLF LATER IN
THE DAY AHEAD OF OUR NEXT WEATHER MAKER.

THERE WILL BE A BRIEF PERIOD OF GUSTY WINDS OVERNIGHT...IN THE
MTNS.

NEXT STORM IS EXPECTED TO MOVE ACROSS THE DEEP SOUTH WEDNESDAY
INTO THURSDAY. POTENTIAL FOR SUB- VFR CONDITIONS WILL EXIST ACROSS
THE AREA WEDNESDAY NIGHT INTO THURSDAY ALONG WITH MEASURABLE
SNOWFALL...HIGHER THREAT FOR SOUTHERN AREAS LIKE BCB-LYH-DAN...BUT
THINK ALL TAF SITES WILL SEE SUB VFR CIGS.

YET ANOTHER CLIPPER MAY CROSS THE AREA THURSDAY NIGHT INTO
FRIDAY.

WHILE LESS PROBABLE...THE WESTERN EXTENT OF A COASTAL SYSTEM
COULD TEAM UP WITH THE CLIPPER AND BRING THE EASTERN PORTION OF
THE FORECAST REGION A GREATER COVERAGE OF WINTRY PRECIPITATION FOR
THE END OF THE WEEKEND.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
VA...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
     AFTERNOON FOR VAZ009-012-017-033-043-044-058-059.
     WINTER STORM WARNING FROM 7 PM WEDNESDAY TO 9 AM EST THURSDAY
     FOR VAZ015-016-032.
NC...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
     AFTERNOON FOR NCZ005-006.
     WINTER STORM WARNING FROM 7 PM WEDNESDAY TO 9 AM EST THURSDAY
     FOR NCZ001>004-018>020.
WV...NONE.
-- End Changed Discussion --

&&

$$
SYNOPSIS...PC
NEAR TERM...DS/WP
SHORT TERM...PC/WP
LONG TERM...NF
AVIATION...DS/WP