Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 300528
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1228 AM EST FRI JAN 30 2015

.SYNOPSIS...
LOW PRESSURE WILL MOVE RAPIDLY EAST ACROSS THE OHIO VALLEY
TONIGHT AND INTO NEW ENGLAND BY FRIDAY MORNING. A SURFACE COLD
FRONT WILL TRAIL SOUTH FROM THE LOW...AND WILL SWEEP SOUTHEAST
ACROSS THE OHIO VALLEY TONIGHT...THEN THROUGH THE MID ATLANTIC
REGION FRIDAY MORNING. HIGH PRESSURE WILL THEN BUILD ACROSS THE
REGION FOR FRIDAY NIGHT 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 TODAY/...
AS OF 1124 PM EST THURSDAY...
MADE SOME MINOR ADJUSTMENTS IN TEMPERATURES AND DEW POINT
TEMPERATURES FOR TONIGHT. SFC TEMPERATURES WERE RUNNING A LITTLE
WARMER IN A FEW LOCATIONS...BUT WILL DROP BEHIND THE COLD FRONT.
THE COLD FRONT HAS REACH THE MOUNTAINS TONIGHT AND WILL MOVE EAST
ACROSS THE REGION FRIDAY MORNING. KFCX 88D SHOWING LIGHT RETURNS
ALONG THE WESTERN SLOPES. BOTH THE NAM AND HRRR SUPPORT CURRENT
FORECAST WITH UPSLOPE SNOW SHOWERS AND SNOW FLURRIES LATER
TONIGHT. INITIALLY EXPECTED SOME RAIN SHOWERS BEFORE TRANSITION
OVER TO SNOW TONIGHT. WINTER WEATHER ADVISORIES CONTINUES FOR
WESTERN GREENBRIER INTO FRIDAY. WIND ADVISORIES REMAIN ALONG AND
WEST OF THE BLUE RIDGE INTO FRIDAY NIGHT.

AS OF 715 PM EST THURSDAY...

CURRENT FORECAST IS ON TRACK WITH ALL OF THE ACTION YET TO COME A
LITTLE BIT LATER THIS EVENING. APPROACHING COLD FRONT IS CURRENTLY
ENTERING WEST VIRGINIA AND EASTERN KENTUCKY WHERE WINDS HAVE COME
AROUND TO NW AND RADAR SHOWS SOME LIGHT RETURNS BEHIND THE FRONT.
TEMPS WILL BE FALLING BEHIND THE FRONT AND EXPECT WE WILL FALL
ABOUT 10F BELOW CURRENT VALUES FOR LOWS OF LOWER 30S EAST OF THE
RIDGE WITH LOW/MID 20S WEST.

THE FRONT SHOULD REACH THE WESTERN SLOPES OF THE APPALACHIANS
AROUND 9PM AND START TO KICK OFF UPSLOPE SNOW SHOWERS. CURRENT
SNOW ACCUMULATION FORECAST LOOKS GOOD BASED ON MESO MODELS WITH 2
TO 4 INCH ADVISORY CRITERIA SNOW FOR WESTERN GREENBRIER INTO
FRIDAY MORNING AND LIGHTER AMOUNTS FURTHER SOUTH ALONG THE WESTERN
SLOPES. THE NC MOUNTAINS ARE LOOKING GOOD FOR AROUND 2 INCHES.

WINDS ARE CURRENTLY QUITE TAME BUT THAT WILL CHANGE BEHIND THE
FRONT. WINDS WILL BECOME NW AND REALLY START TO BLOW AFTER
MIDNIGHT WHEN THE WIND ADVISORIES START TO GO INTO EFFECT. GUSTS
OF 50 MPH TO 55 MPH CAN BE EXPECTED FOR THE NC MOUNTAINS INTO THE
GRAYSON HIGHLANDS...AND 40 MPH TO 50 MPH GUSTS WILL SPREAD NORTH
INTO THE BLUE RIDGE OVERNIGHT. THE WINDY CONDITIONS WILL CONTINUE
THROUGH FRIDAY BEFORE GRADUALLY SUBSIDING TOMORROW NIGHT.

PREVIOUS AFD...

NORTHWEST WINDS WILL BEGIN TO INCREASE AND THE UPSLOPE RAIN/SNOW
MACHINE WILL INITIATE OVER SOUTHEAST WEST VIRGINIA...SOUTH INTO
THE NORTHERN MOUNTAINS OF NORTH CAROLINA. OUR LATEST SNOWFALL
TOTALS DO NOT DIFFER GREATLY FROM OUR PRIOR FORECAST. ADVISORY
LEVEL SNOWS STILL LOOK PROMISING ACROSS WESTERN GREENBRIER COUNTY
IN THE TWO TO FOUR RANGE. HAVE INCREASED WESTERN PARTS OF
GRAYSON...ASHE...AND WATAUGA COUNTIES INTO THE ONE TO TWO INCH
RANGE. LOW TEMPERATURES TONIGHT WILL RANGE FROM THE LOW TO MID 20S
ACROSS THE MOUNTAINS WITH READINGS AROUND 30 TO THE LOWER 30S
ACROSS THE PIEDMONT.

WIND GUSTS ARE EXPECTED TO REACH ADVISORY LEVEL TONIGHT...FIRST
ACROSS THE NORTHERN MOUNTAINS NORTH CAROLINA AND THE GRAYSON
HIGHLANDS A LITTLE AFTER MIDNIGHT. AS THE NIGHT
PROGRESSES...ADVISORY LEVEL GUSTS WILL SPREAD NORTH ACROSS THE
HIGHER RIDGES OF SOUTHWEST VIRGINIA...AND THE WESTERN PORTIONS OF
WESTERN GREENBRIER COUNTY. THE HIGHER TERRAIN OF
GRAYSON...ASHE...AND WATAUGA MAY BE APPROACH GUSTS WITH SPEEDS AT
HIGH WIND WARNING CRITERIA FRIDAY MORNING. THE GUSTS WILL WEAKEN
JUST SLIGHTLY DURING FRIDAY AFTERNOON...PRIOR TO AN EXPECTED BRIEF
INCREASE FRIDAY EVENING. SNOW WILL GRADUALLY COME TO AN END DURING
THE DAY...BUT LINGER THE LONGEST ACROSS SOUTHEAST WEST VIRGINIA.
HIGH TEMPERATURES WILL RANGE FROM THE MID 20 TO LOWER 30S ACROSS
THE MOUNTAINS...WITH MANY OF THESE READINGS OCCURRING EARLY IN THE
DAY WITH FALLING TEMPERATURES THEREAFTER. THE PIEDMONT WILL
EXPERIENCE HIGHS IN THE UPPER 30S TO LOWER 40S.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
AS OF 240 PM EST THURSDAY...

LOW PRESSURE OFF THE NEW ENGLAND COAST AND HIGH PRESSURE SLIDING
ACROSS THE OHIO VALLEY WILL KEEP A PRESSURE GRADIENT AND WINDY/GUSTY
CONDITIONS ACROSS THE REGION INTO MONDAY EVENING. THROUGH THE NIGHT
HIGH PRESSURE EDGES INTO THE AREA WITH SOME LOCATIONS BEING ABLE TO
DECOUPLE WHILE BREEZY/GUSTY CONDITIONS REMAIN ACROSS THE MOUNTAINS.
MORNING LOWS WITHOUT THE WIND WILL RANGE FROM 5F TO 15F ACROSS THE
MOUNTAINS TO AROUND 20F EAST OF THE BLUE RIDGE. IF MIXING CONTINUES
INTO SATURDAY MORNING...WIND CHILLS NEAR ZERO ACROSS THE HIGHER
ELEVATIONS TO AROUND 10F ABOVE IN THE LOWER ELEVATIONS. IN THE
EAST...UPPER TEEN WIND CHILLS LIKELY. HIGH PRESSURE BUILDS OVER THE
REGION SATURDAY...THEN SLIDES TO THE SOUTHEAST SATURDAY NIGHT.
MOSTLY SUNNY SKIES SATURDAY WITH TEMPERATURES WARMING INTO THE UPPER
30S WEST TO MID 40S EAST. THE NEXT PRECIPITATION MAKER WILL PUSH
CLOUDS OVER THE AREA SATURDAY NIGHT WITH LOWS DROPPING JUST BELOW
FREEZING.

COMPLICATED WEATHER PATTERN WILL BRING PRECIPITATION INTO THE AREA
SUNDAY. AN UPPER LEVEL LOW OVER THE SOUTHWEST UNITED STATES WILL
THROW ENERGY AND MOISTURE INTO THE PLAINS. AN UPPER LEVEL NORTHERN
STREAM TROUGH WILL SWING OUT OF THE ROCKIES SATURDAY NIGHT. A SERIES
OF SHORT WAVES WILL TRACK ACROSS THE MID WEST AND EVENTUALLY SPIN UP
A SURFACE WAVE OVER THE TENNESSEE VALLEY. ALL THIS ENERGY/MOISTURE
WILL TRACK IN ZONAL FLOW AND INTO THE DEPARTING SURFACE RIDGE. THE
FIRST SIGNS OF MEASURABLE PRECIPITATION MAY HOLD OFF UNTIL THE
AFTERNOON. THE SURFACE LOW AND UPPER LEVEL DYNAMICS COMES ACROSS THE
AREA SUNDAY NIGHT AND HAVE RAISED POPS INTO THE HIGH LIKELY CATEGORY.

THE TOUGH QUESTION NOW DEALS WITH P-TYPE. TEMPERATURES AND
THICKNESSES START COLD ACROSS THE MOUNTAINS FOR PRECIPITATION TO
FALL AS SNOW. IF DRY AIR IS LEFT-OVER FROM DEPARTING
HIGH...PRECIPITATION FALLING COULD SEND WET BULB TEMPERATURES DOWN
BELOW FREEZING (NAM)...KEEPING MOUNTAIN PRECIPITATION AS SNOW AND A
COLD RAIN IN THE EAST. IF THE SURFACE LOW BECOMES STRONGER...MORE
WARM AIR WILL SURGE INTO THE AREA (GFS) CHANGING SNOW OVER TO RAIN
THROUGH THE DAY SUNDAY...THEN COLD AIR ENTERS LATE SUNDAY NIGHT TO
CHANGE RAIN BACK TO SNOW. BEING RIGHT IN THE TRACK OF THE LOW AND
LIMITED DENDRITE GROWTH NOT SUPPORTING STAYING ALL SNOW...WE WILL
LEAN TO A MOSTLY RAIN EVENT SUNDAY...CHANGING OVER TO SNOW WHEN THE
COLD FRONT PASSES SUNDAY NIGHT. ALSO...WE ARE NOT LOOKING AT A WEDGE
LINGERING IN THE REGION...THEREFORE HIGHLY CONFIDENT PRECIPITATION
WILL BE RAIN OR SNOW...NOT A MIXTURE OR CHANGE OVER TO FREEZING
RAIN/SLEET.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
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 /05Z FRIDAY THROUGH TUESDAY/...
AS OF 1215 AM EST FRIDAY...

THE STRONG ADVERTISED ALBERTA CLIPPER COLD FRONT MOVING RAPIDLY
THROUGH THE WESTERN PART OF THE CWA AT THIS HOUR...NEAR BCB AND
ALREADY THROUGH LWB/BLF. VERY QUICKLY CIGS DROP INTO THE MVFR/IFR
RANGE BEHIND THE FRONT WITH MIXED PCPN...WHICH SHOULD RAPIDLY
CHANGE TO SNOW WITH STRONG LOW-LEVEL COLD ADVECTION. ALONG AND
EAST OF THE BLUE RIDGE...WINDS LIGHT AND VARIABLE WITH MOSTLY LOW
END VFR CIGS AT THIS HOUR. MODELS NOW DEPICTING A WAVE THAT WILL
RIDE ALONG THE FRONT...WHICH COULD SLIGHTLY DELAY ITS PROGRESS
INTO THE PIEDMONT AND FURTHERMORE BRING A WAVE OF -SHRA TO BCB/ROA
BEFORE THE COLD FRONT ARRIVES OR SHORTLY THEREAFTER. HAVE THUS INTRODUCED
THESE CHANGES TO THE TAFS...SLIGHTLY DELAYING THE ARRIVAL OF THE
FRONT INTO ROA/LYH/DAN AND ALSO INTRODUCING -SHRA TO BCB/ROA THAT
WERE NOT IN THE 00Z TAFS. UPSLOPE -SHSN SHOULD CONTINUE TO BE
ENHANCED WEST OF THE BLUE RIDGE OVERNIGHT INTO EARLY FRI...WITH
OCCASIONAL MVFR TO BRIEFLY IFR VSBYS AND IFR-LIFR CIGS. CONDITIONS
SHOULD BEGIN TO IMPROVE AFT 14Z WITH JUST FLURRIES OR OCCASIONAL
-SHSN THROUGH THE EARLY AFTERNOON WEST OF THE BLUE RIDGE. EXPECT
MVFR CIGS TO HOLD MUCH OF THE DAY WEST OF THE BLUE RIDGE...BUT
CLOUDS SHOULD SCATTER OUT TO THE EAST. EXPECT VFR CIGS AROUND 22Z
BLF/LWB/BCB...BECOMING MOSTLY SKC OR JUST SCT ALL SITES AFT 22Z.

MAIN CONCERN THROUGH THE TAF VALID PERIOD WILL BE STRONG...GUSTY
NORTHWEST WINDS. WITH A 50KT NORTHWESTERLY LLJ OVER THE REGION
LATE TONIGHT/EARLY FRI AS A TIGHT PRESSURE GRADIENT DEVELOPS
BETWEEN THE ADVANCING CANADIAN HIGH AND THE DEPARTING SFC LOW
NORTHEAST U.S...30-40KT WIND GUSTS WILL BE POSSIBLE LATE TONIGHT
AND THROUGH EARLY AFTERNOON FRI. SUSTAINED WINDS SHOULD BE MAINLY
IN THE 15-25KT RANGE. WINDS REMAIN GUSTY EVEN INTO FRI
EVENING...BUT SHOULD DROP BELOW 25KTS FAIRLY QUICKLY AFT 02Z.
WINDS OVERALL WILL AVERAGE 10KTS LESS ACROSS THE PIEDMONT.

MEDIUM CONFIDENCE IN CIGS AND VSBYS THROUGH 14Z...THEN MEDIUM TO
HIGH CONFIDENCE.
MEDIUM TO HIGH CONFIDENCE IN WIND SPD/DIR THROUGH THE TAF VALID
PERIOD.

EXTENDED DISCUSSION...

WINDS WILL DIMINISH FRIDAY NIGHT AS HIGH PRESSURE MOVES INTO THE
REGION FROM THE WEST. ANY REMAINING LOW CLOUDS LINGERING ACROSS
EASTERN WV SHOULD DISSIPATE...WITH VFR CIGS EXPECTED FRI NIGHT AND
SAT. 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 MOSTLY WINTER
PRECIPITATION WITH THIS EVENT...WHILE THE SOUTHERN AREAS SHOULD
SEE MOSTLY RAIN. IN BETWEEN...LOCATIONS SUCH AS
BCB/ROA/LYH...COULD SEE A MIX OF RAIN AND SNOW. MOUNTAIN SNOW
SHOWERS WITH MVFR CIGS/VSBYS WILL CONTINUE INTO MON...WITH STRONG
AND GUSTY WINDS ALL AREAS BY MONDAY AFTERNOON. IMPROVING
CONDITIONS ARE EXPECTED BY TUESDAY.

&&

.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.
NC...WIND ADVISORY UNTIL 9 PM EST THIS EVENING FOR NCZ002.
     WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NCZ001-018.
WV...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR WVZ508.

&&

$$
SYNOPSIS...DS
NEAR TERM...DS/KK/MBS
SHORT TERM...RCS
LONG TERM...MBS
AVIATION...DS/RAB


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