Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 251206
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
706 AM EST SUN JAN 25 2015

.SYNOPSIS...
AN ALBERTA CLIPPER WILL MOVE FROM THE UPPER MIDWEST INTO THE
TENNESSEE VALLEY TODAY...THEN CROSS THE CENTRAL APPALACHIANS
TONIGHT AND MONDAY. THIS WILL USHER IN COLDER AIR BEHIND IT AND
SNOW SHOWERS ON THE WESTERN SLOPES OF THE APPALACHIANS LASTING
INTO TUESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 705 AM EST SUNDAY...

WINDS HAVE SETTLED DOWN QUICK A BIT THIS MORNING AND ARE LESS THAN
10 KTS ACROSS THE ENTIRE FCST AREA...EVEN AT HIGHER ELEVATIONS.
SOME GUSTS INTO THE TEENS AT TIMES BUT HAVE DECREASED WINDS IN THE
FCST MORE QUICKLY NOW THIS MORNING. LOW-TO-MID CLOUD DECK HAS
SHIFTED ACROSS NORTHERN PORTION OF AREA AND SHOULD DISSIPATE AS IT
CONTINUES TO SHIFT NORTHEAST...MEANWHILE SCATTERED HIGH CLOUDS ARE
BEGINNING TO DRIFT ACROSS THE APPALACHIANS WITH A LITTLE
OROGRAPHICALLY-INDUCED CIRRUS AREAS EAST OF THE BLUE RIDGE. HAVE
ADJUSTED NEAR TERM FCST FOR SKY COVER A BIT. SOME OF THE 06Z
GUIDANCE SUGGESTING A SLIGHT ADDITIONAL SLOW DOWN TO TIME OF
ARRIVAL OF ANY MEASURABLE PRECIP TONIGHT...BUT HAVE NOT ADJUSTED
THAT YET.

PREV DISCUSSION AS OF 420 AM EST SUNDAY...

WINDS DIMINISHING STEADILY NOW IN HIGHER ELEVATIONS OF NORTH
CAROLINA MOUNTAINS...AS SURFACE RIDGE OF HIGH PRESSURE BEGINS TO
BUILD IN FROM THE OHIO VALLEY. WIND ADVISORY WAS THUS DROPPED.
BEGINNING TO LOSE THE THE UPPER LEVEL CYCLONIC COMPONENT TO THE
FLOW AS WELL...AND AS SUCH...LOW CLOUDS COVER IN MTNS BEGINNING TO
BREAK UP SOMEWHAT.

AS WARM ADVECTION INCREASES WITH LOW LEVEL FLOW TURNING SW AHEAD
OF ADVANCING CLIPPER SYSTEM AND ASSOCIATED SFC LOW AND COLD FRONT
DROPPING INTO THE CENTRAL MISSISSIPPI AND LOWER OHIO
VALLEYS...TEMPS TODAY SHOULD BE QUITE MILD DESPITE INCREASING MID
AND HIGH LEVEL CLOUD COVER. WENT WITH WARMEST GUIDANCE OF 40S IN
MTNS AND LOWER 50S IN PIEDMONT. MAYBE EVEN MID 50S FOR SOUTHSIDE
AND NORTH CENTRAL NC THIS AFTERNOON. THIS IS BUMPED UP A COUPLE
DEGREES FROM PREVIOUS FCST.

AS CLOUDS THICKEN BY TONIGHT...SHOULD KEEP TEMPERATURES FROM
DROPPING TOO QUICKLY AND QUESTION IS WILL BOUNDARY LAYER TEMPS GET
COLD ENOUGH FOR ANY PRECIP TO FALL AS SNOW THAT COMES IN AHEAD OF
SFC LOW...GENERALLY TIMED FOR MIDNIGHT OR LATER IN THE WEST.
WHILE THIS CLASSIFIES AS A CLIPPER SYSTEM...IT HAS BEEN TRENDING
TO DIG A LITTLE DEEPER AND SLOW DOWN A BIT WITH NEW MODEL
CYCLES...SO MEASURABLE PRECIP MIGHT NOT REACH EAST OF THE BLUE
RIDGE UNTIL CLOSER TO DAWN MONDAY MORNING. THERMAL PROFILES OF NAM
AND OTHER HIGH RESOLUTION MODELS SUGGEST MOST AREAS WILL NOT SEE
SNOW TONIGHT EXCEPT FOR HIGHEST ELEVATIONS...3000 FT OR EVEN
HIGHER. I MAY EVEN HAVE TEMPS TOO COLD AT THESE HIGHEST ELEVATIONS
AND CHANGING TO SOME ACCUMULATING LIGHT SNOW TOO EARLY. AN INCH OR
SO IS CERTAINLY POSSIBLE BY MONDAY MORNING AT PLACES LIKE BEECH
MTN NC...MT ROGERS VA...TO WESTERN GREENBRIER COUNTY WV AND
HIGHER RIDGES IN THE ALLEGHANY HIGHLANDS OF VIRGINIA...BUT MUCH OF
THIS DEPENDS ON IF PRECIP RATES CAN BRIEFLY GET HIGH ENOUGH TO
START STICKING...WITH THE GROUND GETTING FAIRLY WARM SUNDAY. BY
12Z MONDAY THE SFC LOW IS STILL IN THE FAR SW PART OF THE FCST
AREA AND COLDER AIR NOT EXPECTED TO FILTER IN BEHIND WITH BETTER
UPSLOPE FLOW UNTIL LATER IN THE DAY MONDAY. FOR MONDAY MORNING
LOWS...GOING WITH MILDER MET GUIDANCE GIVEN WARM ADVECTION
CONTINUING AND SOLID CLOUD COVER.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 340 AM EST SUNDAY...

AS THE CLIPPER APPROACHES THE SOUTHERN APPALACHIANS MONDAY
MORNING...A SECONDARY LOW WILL DEVELOP OFF THE CAROLINA COAST.
DURING THE DAY MONDAY...THE CLIPPER WILL BECOME A COASTAL LOW. AS
THE COASTAL LOW BECOMES DOMINATE BY LATE MORNING...LOW LEVEL FLOW
WILL TURN EASTERLY...THEN NORTHERLY IN THE AFTERNOON...DROPPING
TEMPERATURES ACROSS THE NORTHERN HALF OF RNK CWA. THE COLD FRONT
SHOULD STALL ACROSS THE SOUTHERN OHIO VALLEY MONDAY MORNING...THEN
RACE ACROSS THE REGION EARLY AFTERNOON. MOUNTAIN TEMPERATURES WILL
PEAK BY MID MORNING THEN FALL IN THE AFTERNOON. MODELS CONTINUE TO
RUN WARM MONDAY BUT LOWERED THEM WITH INCREASING EASTERLY FLOW IN
THE MORNING AND THE COLD FRONT ZIPPING ACROSS THE AREA IN THE
AFTERNOON. THE RESULTING P-TYPE WOULD BE MOSTLY RAIN IN THE MORNING
TURNING TO SNOW ACROSS THE HIGHER ELEVATIONS AROUND NOON THEN ACROSS
THE REST OF THE MOUNTAINS BY RUSH HOUR MONDAY EVENING.
ADDITIONAL ACCUMULATIONS MONDAY AROUND AN INCH.

MONDAY NIGHT...THE ONCE CLIPPER TURNED COASTAL LOW TRACKS NORTH AND
BECOMES A BONAFIDE NOR-EASTER. WITH THE TRACK CLOSE TO THE
COAST...WRAP-AROUND MOISTURE MAY KEEP RAIN ACROSS THE PIEDMONT
THROUGH MIDNIGHT...WHILE THE MOUNTAINS HAVE SCATTERED SNOW SHOWERS.
LATE MONDAY NIGHT...A SIGNIFICANT SHORT WILL DROP SOUTH OUT OF THE
GREAT LAKES...BRING MORE ACCUMULATING SNOW TO THE MOUNTAINS TUESDAY
MORNING. THIS WAVE WILL BE STRONG ENOUGH TO OVER COME DOWNSLOPING
AND PUSH SNOW EAST OF THE BLUE RIDGE TUESDAY MORNING. ACCUMULATIONS
ACROSS THE MOUNTAINS COULD RANGE 1-3 INCHES AND UNDER AN INCH EAST
OF THE BLUE RIDGE INTO THE FOOTHILLS. BY TUESDAY AFTERNOON...THE
SNOW STOPS WITH THE EXCEPTION OF WESTERN SLOPES WHERE SNOW SHOWERS
WILL CONTINUE INTO TUESDAY NIGHT. NOT LOOKING AT MUCH UPSLOPE WITH
NORTHERLY WINDS AND HIGH PRESSURE BUILDING IN BY WEDNESDAY MORNING.

ONCE THE NOR-EASTER BOMBS OFF THE MID ATLANTIC COAST MONDAY
NIGHT...A PRESSURE GRADIENT WILL REMAIN OVER THE REGION UNTIL HIGH
PRESSURE BUILDS IN WEDNESDAY MORNING. THIS GRADIENT WILL KEEP BREEZY
CONDITIONS OVER THE REGION. PRESSURE RISES BEHIND THE FRONT ON
MONDAY AND AGAIN TUESDAY AFTERNOON AND EVENING WILL INCREASE WINDS
AND GUSTS BUT SHOULD NOT EXCEED ADVISORY CRITERIA. WIND CHILLS DROP
INTO THE TEENS MONDAY MORNING AND TO NEAR 10F ABOVE WEDNESDAY
MORNING.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 230 PM EST SATURDAY...

A HIGH AMPLITUDE UPPER TROF ALONG THE EAST COAST WILL LIFT OUT BY
WEDNESDAY EVENING INTO WEDNESDAY NIGHT. MEANWHILE...A 1026 MB SFC
HIGH PRESSURE WILL SLIDE EAST ACROSS THE REGION WEDNESDAY INTO
WEDNESDAY NIGHT. AS HIGH PRESSURE MOVES EAST ACROSS THE AREA...THE
LOW LEVEL WINDS BACK AROUND WEDNESDAY...BRINGING AN END TO ANY
LINGERING UPSLOPE SNOW SHOWERS OR SNOW FLURRIES WITH TEMPERATURES
MODERATING.

HIGH TEMPERATURES WEDNESDAY WILL RANGE FROM THE UPPER 20S IN THE
MOUNTAINS TO THE LOWER 40S IN THE PIEDMONT. ON WEDNESDAY NIGHT...THE
HIGH CENTER WILL BE LOCATED ACROSS EASTERN NORTH CAROLINA...AND A
LOW PRESSURE CENTER IN THE CHICAGO AREA WITH AN APPROACHING TRAILING
COLD FRONT IN THE OHIO VALLEY. LOW TEMPERATURES WEDNESDAY NIGHT WILL
GENERALLY BE FROM THE UPPER TEENS TO THE UPPER 20S.

A COLD FRONT WILL MOVE EAST ACROSS OUR AREA THURSDAY AFTERNOON INTO
FRIDAY. HIGH TEMPERATURES THURSDAY WILL WARM INTO THE UPPER 30S IN
THE NORTHWEST MOUNTAINS TO THE UPPER 40S IN THE PIEDMONTS. WILL KEEP
PTYPE AS RAIN/SNOW MIXTURE WITH HIGHEST PROBABILITIES IN THE
NORTHWEST...AS INDICATED BY THICKNESS AND TEMPERATURE PROFILES.
ENOUGH COLD AIR ARRIVES BY THURSDAY NIGHT FOR MAINLY SNOW SHOWERS OR
SNOW FLURRIES. LOW TEMPERATURES THURSDAY NIGHT WILL VARY FROM THE
MID 20S IN THE MOUNTAINS TO THE LOWER 30S IN THE PIEDMONT.

THE COLD FRONT PUSHES INTO THE ATLANTIC OCEAN ON FRIDAY AS THE UPPER
TROUGH SETUPS ALONG THE EAST COAST. A WEAK SHORTWAVE WILL ROTATE
EAST ACROSS OUR AREA WITH SOME SCATTERED SHOWERS FOR THE EAST. HIGHS
FRIDAY WILL RANGE FROM NEAR THE FREEZING MARK IN THE NORTHWEST
MOUNTAINS TO THE UPPER 40S IN THE PIEDMONT. WITH THE NORTHWEST FLOW
ALOFT MAY BE SOME SNOW FLURRIES IN THE NORTHWEST UPSLOPE LOCATIONS
FRIDAY NIGHT...BUT MODELS LOOKED RELATIVELY DRY. LOW TEMPERATURES
FRIDAY NIGHT WILL GENERALLY BE IN THE MID TEENS TO THE MID 20S. THE
UPPER FLOW BECOMES WESTERLY SATURDAY...WITH HIGHS IN THE MID 20S IN
THE NORTHWEST MOUNTAINS TO THE MID 40S IN THE SOUTHEAST. MOISTURE
SLOWLY APPROACHES FROM THE WEST SATURDAY EVENING INTO SUNDAY
MORNING.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AS OF 650 AM EST SUNDAY...

MAINLY VFR CLOUDS TODAY UNDER INFLUENCE OF A RIDGE AND IN ADVANCE
OF APPROACHING CLIPPER-TYPE FRONT. WINDS RELATIVELY LIGHT WITH
SHIFT TO SOUTH OR AT TIMES SOUTHEAST LATER TODAY..BUT LESS THAN 10
KTS. CLOUDS HIGH CLOUDS THICKEN LATE IN THE DAY BUT REMAIN VFR
UNTIL AFTER DARK WHEN THEY WILL QUICLY LOWER TO IFR IN LIGHT RAIN
AHEAD OF THE CLIPPER SYSTEM...STARTING AT WESTERN SITES BY 0300
UTC OR 2200 LOCAL TIME...AND AFTER 0600 UTC AT EASTERN SITES. THE
LOWER LEVEL SOUTHERLY FLOW SHOULD HELP LOWER CEILINGS MAY RESULT
IN CONDITIONS NEAR OR BELOW LIFR CATEGORY BEFORE 12Z...BUT
PRECIPITATION SHOULD REMAIN LIGHT. AT BLF AND LWB THERE MAY BE
SNOW MIXED IN AT TIMES...AND EVEN MAY START BRIEFING AS SNOW...AND
THEN CLOSER TO 1200 UTC MONDAY MAY SWITCH OVER TO ALL SNOW BUT
CONFIDENCE LOW IN THIS CHANGE OVER AS LOW LEVEL ATMOSPHERE WILL BE
VERY CLOSE TO RAIN/SNOW LINE. VERY UNLIKELY TO STICK ON PLANES OR
RUNWAY SURFACES HOWEVER THROUGH 1200 UTC MONDAY.

MONDAY...EXPECT MVFR TO IFR CEILINGS AND VISIBILITIES TO PERSIST WITH
THE CLIPPER AND THE ASSOCIATED LIGHT SNOW. FLOW TURNS MORE
WESTERLY BY MIDDAY AND COLDER AIR FILTER IN BEHIND SURFACE
FRONT...AND RAIN OR RAIN SHOWERS WILL CHANGE OVER TO SNOW AT BLF
ADN LWB...AND INTERMITTENT SNOW SHOWERS AT BCB...PERHAPS ROA AS
WELL. LATE MONDAY AND MONDAY NIGHT SOME VERY LIGHT ACCUMULATIONS
OF SNOW ARE MORE LIKELY AT BLF AND LWB AND NW WINDS INCREASE AS
WELL. MVFR TO VFR CONDITIONS SHOULD RETURN AT ROA, LYH, AND DAN
DURING THE DAY MONDAY.

TUESDAY...A REINFORCING SHOT OF ENERGY COMES IN THROUGH THE
NORTHWEST UPPER FLOW. HIGH CONFIDENCE FOR MVFR CONDITIONS IN THE
MOUNTAINS BOTH MONDAY AND TUESDAY WITH OCNL IFR DUE TO SCATTERED
SNOW SHOWERS. LOWER CONFIDENCE THE MVFR CIGS WILL SPILL OVER THE
MOUNTAINS INTO THE ROANOKE VALLEY AND SOUTHSIDE VIRGINIA.

BY MONDAY NIGHT...ANY PTYPE WILL BE SNOW DUE TO COLDER
TEMPERATURES. WINDS WILL ALSO BE GUSTY MONDAY NIGHT AND TUESDAY
BEHIND THE REINFORCING SURGE OF COLD AIR.

BY WEDNESDAY...HIGH PRESSURE WILL PROVIDE A DAY OF TRANQUIL
WEATHER AND REGION-WIDE VFR CONDITIONS.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.

&&

$$
SYNOPSIS...SK
NEAR TERM...SK
SHORT TERM...RCS
LONG TERM...KK
AVIATION...AMS/PM/SK


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