Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 201500
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1000 AM EST THU NOV 20 2014

.SYNOPSIS...
ASIDE FROM A FEW FLURRIES AND SNOW SHOWERS WEST OF THE
BLUE RIDGE...HIGH PRESSURE BUILDING IN FROM THE WEST WILL BRING
QUIET BUT BREEZY CONDITIONS...WITH CONTINUED BELOW NORMAL
TEMPERATURES...THROUGH THE END OF THE WORKWEEK AND INTO THE FIRST
PART OF THE WEEKEND. AS THE HIGH SLIPS OFF TO OUR EAST ON SUNDAY...A
STRONG LOW PRESSURE SYSTEM WILL MOVE UP THE MISSISSIPPI VALLEY AND
PUSH A WARM FRONT THROUGH THE AREA. THIS WILL BRING A GOOD CHANCE OF
RAIN TO OUR FORECAST ON SUNDAY...BUT ALSO SOME WARMER TEMPERATURES AS
WE HEAD INTO NEXT WEEK. HOWEVER...THE WARM UP WILL BE SHORT LIVED AS
COLD HIGH PRESSURE BUILDS IN AGAIN FROM THE WEST.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 959 AM EST THURSDAY...

MADE SOME MINOR ADJUSTMENTS IN TEMPERATURES AND DEW POINTS WITH
CURRENT OBS AND MODEL TRENDS. AS SEEN IN HIRESW-ARW AND
NAM...KEPT THE MENTION OF ISOLATED SNOW SHOWERS OR SNOW FLURRIES
IN THE NORTHWEST MOUNTAINS.



AS OF 355 AM EST THURSDAY...

SFC LOW MOVING THROUGH THE GREAT LAKES WILL BE PUSHING A WEAK COLD
FRONT THROUGH THE REGION THIS MORNING. THIS WILL EVENTUALLY SHIFT
WINDS AROUND TO A WND DIRECTION. THERE MAY BE SOME UPSLOPE
FLURRIES/SNOW SHOWERS FOR THE FAR WESTERN SLOPES IN WV BUT WOULD
LIKE TO SEE FLOW MORE NEWLY AND A BIT MORE MOISTURE THAN IS
CURRENTLY AVAILABLE TO GET ANYTHING APPRECIABLE. SOME CLOUDS MAY
ALSO SPILL EWE PAST THE RIDGE SINCE DOWNSLOPE WILL NOT BE
MAXIMIZED. IN ANY EVENT...OVERALL FLAVOR OF THE DAY WILL BE FAIR
EAST OF THE RIDGE...IMPROVING TO THE WEST AS THE DAY WEARS
ON...AND BECOMING WINDY EVERYWHERE AS DIURNAL MIXING TAPS SOME OF
THE BRISK LOW LEVEL WINDS. TEMPS WILL CONTINUE TO MODERATE
AND...WHILE STILL REMAINING WELL BELOW NORMAL...LOCATIONS EAST OF
THE RIDGE SHOULD RISE ABOVE 50F FOR THE FIRST TIME IN A WHILE.

HIGH PRESSURE PUSHES IN FROM THE NORTHWEST TONIGHT. THIS WILL BRING
WINDS AROUND TO A MORE NEWLY DIRECTION AND GET UPSLOPE
FLURRIES/SNOW SHOWERS GOING AGAIN FOR THE FAR WESTERN SLOPES.
MAYBE A DUSTING FOR THE HIGHER ELEVATIONS. MODEL SOUNDINGS ALSO
INDICATE A PERIOD OF BETTER DOWNWARD MOMENTUM TRANSFER TONIGHT SO
WINDS LOOK TO STAY A BIT GUSTY ESPECIALLY FOR THE RIDGES.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS OF 345 AM EST THURSDAY...

THE FINAL ARCTIC HIGH IN THE SERIES OF FOUR OVER THE PAST WEEK
WILL BE CENTERED OVER THE REGION EARLY FRI. ONE MORE FINAL COLD
DAY WITH TEMPERATURES WELL BELOW NORMAL...ON THE ORDER OF 10 TO 15
DEGREES BELOW NORMAL...NOTHING LIKE THE COLD TEMPERATURES
YESTERDAY AND THE DAY BEFORE. CANNOT COMPLETELY RULE OUT A FEW
LINGERING SNOW FLURRIES ALONG UPSLOPE AREAS OF THE ALLEGHANYS IN
WESTERN GREENBRIER...BUT OTHERWISE...A DRY AND BECOMING MOSTLY
SUNNY DAY. A MODEL BLEND YIELDED A VERY REASONABLE SOLUTION FOR
TEMPERATURES.

FOR SATURDAY...THE REMNANT ARCTIC SFC HIGH WILL MOVE ELSE-SE OF
THE REGION UNDER INCREASINGLY CONFLUENT FLOW ALOFT ACROSS THE MID-
ATLANTIC REGION IN RESPONSE TO A VIGOROUS SOUTHERN STREAM SHORT
WAVE COMING OUT OF THE SW U.S. THE HIGH WILL INITIALLY INTENSIFY
AND SHIFT TO THE SE OF THE REGION BY SAT EVENING. WHILE CERTAINLY
NOT A FAVORABLE POSITION FOR A CLASSIC WEDGE...IT WILL THEN MOVE
EAST OFFSHORE SUN INTO A MORE TYPICAL IN-SIT WEDGE POSITION. A
SHORT WAVE RIDGE WILL BUILD OVER THE REGION BRIEFLY SATURDAY AS
THE INCREASINGLY VIGOROUS SOUTHERN STREAM SHORT WAVE DIGS INTO
TX/LAW AND TAKES ON A SIGNIFICANT NEGATIVE TILT. CLOUDS WILL BE
ON THE INCREASE SATURDAY...BUT THE CWA WILL REMAIN PRECIPITATION
FREE WITH A VERY DRY AIR MASS TO START RESIDING OVER THE REGION.
THIS WILL ALLOW FOR ONE MORE COLD MORNING BEFORE A NOTABLE WARMING
TREND BEGINS SATURDAY AFTERNOON AS SFC WINDS COME AROUND TO THE
SOUTH.

FOR SUN THE STRONGLY NEGATIVE TILTED SHORT WAVE ROTATES QUICKLY
THROUGH THE REGION. THE CONCERNS THAT ARISE WITH THIS SYSTEM ARE
WINTER WEATHER THREAT...SEVERE WEATHER THREAT...AND RAINFALL
AMOUNTS. FOR THE WINTER WEATHER THREAT...THIS APPEARS TO
ESSENTIALLY BE NIL. CLOUDS INCREASE ENOUGH IN SOUTHWEST PARTS OF
THE CWA TO PREVENT MUCH RADIATIONAL COOLING. IN ADDITION...A
STRONG 60KT+ LAW TRAVERSES THE AREA BRINGING WARM/GULF AIR TO
NORMALLY COLDER HIGHER ELEVATIONS EVEN SOONER. THE GREENBRIER
VALLEY AND SOUTHERN SHENANDOAH VALLEY WILL SEE TEMPERATURES JUST
BELOW FREEZING EARLY SUN. THUS...IF PRECIPITATION CAN REACH THESE
AREAS...THERE MAY BE A FEW BRIEF POCKETS OF FREEZING RAIN EARLY
SUN MORNING...BUT SIGNIFICANT PRECIPITATION IS NOT EXPECTED IN
THESE AREAS UNTIL LATE MORNING OR AFTERNOON WHEN TEMPERATURES WILL
BE WELL ABOVE FREEZING. OTHERWISE...AS NOTED...THE WINTER WEATHER
THREAT WITH THIS SYSTEM IS NEAR ZERO.

FOR THE SEVERE WEATHER THREAT...THE DYNAMICS ARE CERTAINLY THERE.
HOWEVER...THERE IS STRONG ENOUGH EVIDENCE OF THE IN-SIT WEDGE AND
A STABLE...COOLER AIR MASS...ALSO ANTECEDENT DRY AIR
MASS/30-DEGREE DEWPOINTS...TO PRECLUDE MUCH THREAT OF SEVERE. NO
THUNDER WAS INHERITED IN THE GRIDS AND NONE WAS ADDED WITH THIS
PACKAGE. THE MAIN CONCERN WOULD BE STRONG SOUTHEAST GRADIENT WINDS
THAT AFFECT THE HIGHER ELEVATIONS OF SE WV/SW VA IN THE TYPICALLY
FAVORED LOCATIONS...E.G...TAZEWELL...MERCER...SMYTH COUNTY REGION.

RAINFALL ALSO DOES NOT APPEAR TO BE A SIGNIFICANT CONCERN. THE
PERIOD OF ANY MODERATE TO HEAVY RAINFALL SHOULD BE LIMITED TO THE
12Z-18Z PERIOD SUN IN THE SOUTHWEST PART OF THE CWA AND 18Z-00Z IN
THE NORTHEAST PART OF THE CWA. CURRENTLY ADVERTISED RAINFALL FOR
SUN IS 1/3RD INCH NORTH TO 2/3RD INCH SOUTH. THIS IS CONSISTENT
WITH PCS LATEST DECREASE IN RAINFALL ACROSS THE REGION FROM LESS
THAN AN INCH NORTH TO AROUND AN INCH NC/VA PIEDMONT COUNTIES.
OVERALL...IT APPEARS THAT THERE COULD BE A SPLIT IN THE HEAVIER
PRECIPITATION ASSOCIATED WITH THE LARGE SCALE SYNOPTIC
SYSTEM...ONE AREA OF HEAVIER RAINFALL ACROSS THE OH VALLEY WITH
THE MAIN SFC LOW TRACK...AND ANOTHER TO THE SOUTHEAST OF THE
REGION CLOSER TO THE COAST...ALTHOUGH SOME ENHANCEMENT OF RAINFALL
ALONG SOUTHEAST FACING SLOPES OF THE BLUE RIDGE SEEMS PROBABLE
WITH INCREASING SOUTHEAST SFC WINDS. HAVE KEPT TEMPERATURES ON THE
COLD SIDE OF GUIDANCE SUN WITH A WEDGE IN PLACE AND SIGNIFICANT
 LIKELY AS THE PRECIPITATION OVERSPREADS THE ANTECEDENT DRY AIR
MASS.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 420 AM EST THURSDAY...

MON WILL BRING THE WARMEST TEMPERATURES THE CWA HAS SEEN IN OVER A
WEEK...WITH 50S POSSIBLE IN THE MOUNTAINS TO AROUND 70 TOWARD
DANVILLE/CASWELL AREA AS THE AREA MOVES INTO A DRY SLOT BETWEEN A
BAROCLINIC ZONE...NOW SHIFTED CLEARLY OFF THE EAST COAST...AND THE
MAIN UPPER TROUGH/COLD FRONT...STILL WELL TO THE WEST OF THE
REGION. SCT SHOWERS APPEAR POSSIBLE WITHIN THE LARGE WARM SECTOR
ACROSS THE REGION...BUT MODELS ARE INCONSISTENT ON PLACEMENT OF
THE BETTER PRECIPITATION. COVERAGE LOOKS SPOTTY ON ALL MODELS...SO
HAVE JUST ADVERTISED MOSTLY CHANCE POPS FOR NOW. IF ANY THUNDER
WERE TO OCCUR...MONDAY WOULD BE THE DAY FOR IT...BUT MID-LEVEL
WARMING AND LACK OF FOCUSED DYNAMICS SHOULD INHIBIT MUCH IF
ANY...THUS IT HAS NOT BEEN ADVERTISED AT THIS POINT.

THE MAIN COLD FRONT BEGINNING A LONG TERM COOLING TREND AGAIN
WILL MOVE THROUGH THE REGION MON NIGHT/EARLY TUE. AN INCREASE IN
FRONTAL ASSOCIATED SHOWERS APPEARS LIKELY WITHIN THIS TIME FRAME
AS THE MAIN UPPER TROUGH LAGS BACK TO THE WEST. COLDER AIR WILL
BEGIN TO FILTER INTO THE REGION THEN THROUGH MID-WEEK. IT SHOULD
THEN BE COLD ENOUGH BY WED NIGHT FOR SNOW SHOWERS IN THE USUAL
UPSLOPE AREAS OF THE ALLEGHANYS AS A CLIPPER SYSTEM COMES THROUGH.
ANOTHER LARGE ARCTIC HIGH APPEARS DESTINED FOR THE REGION FOR
THANKSGIVING TOWARD THE WEEKEND. HOWEVER...THE ECMWF AND GFS
DIVERGE SIGNIFICANTLY TOWARD THE END OF THE WEEK WITH THE ECMWF
INDICATING MUCH MORE POTENTIAL FOR A WESTERN U.S. TROUGH/EASTERN
U.S. RIDGE RS. THE GFS WITH A DEEP EASTERN U.S. TROUGH. THE 00Z
ECMWF CONTINUED THE MARKED DISCREPANCY IN THE LATER PORTIONS OF
THE EXTENDED.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
AS OF 650 AM EST THURSDAY...

ANOTHER ARCTIC SURGE...ALBEIT LESS SIGNIFICANT THAN THE
LAST...HEADED TOWARD THE REGION TODAY. ASSOCIATED CLOUD COVER
BANKED UP AGAINST THE WESTERN SLOPES AND SPILLING INTO THE NEW
RIVER VALLEY EXPECTED TO CONTINUE THROUGH MUCH OF THE DAY.
OVERNIGHT...AS WINDS BECOME MORE NORTHWEST AND UPSLOPE FLOW IS
ENHANCED...CIGS WILL LIKELY LOWER TO MVFR ALONG UPSLOPE AREAS OF
THE ALLEGHANYS. THE NEW RIVER VALLEY AREA AND THE ALLEGHANY
HIGHLANDS WILL SEE SCT MVFR LEVEL CLOUDS...OCCASIONALLY BKN. EAST
OF THE BLUE RIDGE IT SHOULD REMAIN VFR THROUGHOUT THE TAF VALID
PERIOD. A FEW -SHSN OR FLURRIES WILL BE POSSIBLE AFTER MIDNIGHT
INTO THE EARLY MORNING HOURS ALONG UPSLOPE AREAS OF THE
ALLEGHANYS...BUT NO VISIBILITY RESTRICTIONS ARE EXPECTED. WINDS

MAIN CONCERN THROUGH THE TAF VALID PERIOD WILL BE THE WIND. GUSTY
WSW-WND WINDS EXPECTED THROUGH THE TAF VALID PERIOD AS THE
GRADIENT TIGHTENS UP IN RESPONSE TO THE APPROACHING ARCTIC HIGH.
SPEEDS INCREASING TO 1O TO 15KTS WITH GUSTS TO 25KTS POSSIBLE
THROUGH THE LATE MORNING AND AFTERNOON.

MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH THE TAF VALID PERIOD.
HIGH CONFIDENCE IN VSBY THROUGH THE TAF VALID PERIOD. MEDIUM TO
HIGH CONFIDENCE IN WIND SPD/DIR THROUGH THE TAF VALID PERIOD.

EXTENDED DISCUSSION...

FRIDAY THROUGH SATURDAY WILL AGAIN BE VFR...WITH HIGH PRESSURE IN
THE REGION. A MORE SIGNIFICANT SYSTEM WILL APPROACH THE AREA WITH
RAIN AND SUB-VFR CONDITIONS SUNDAY INTO SUNDAY NIGHT. MAY SEE A
BRIEF RETURN TO VFR DURING MONDAY OUTSIDE OF THE MOUNTAINS AS A
DRY SLOT DEVELOPS BETWEEN THE EXITING FRONT FROM SUNDAY AND THE
NEXT UPSTREAM COLD FRONT.

&&

.EQUIPMENT...
AS OF 355 AM EST WEDNESDAY...

THE VISIBILITY SENSOR AT CLAY...LYNCHBURG AIRPORT...WILL BE OUT
OF SERVICE UNTIL PARTS ARRIVE TO REPLACE THE SENSOR. UNTIL THEN
THE VISIBILITY WILL ONLY BE REPORTED WHEN THE CONTROL TOWER IS
STAFFED.

&&

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

&&

$$
SYNOPSIS...MBS
NEAR TERM...KK/MBS
SHORT TERM...RAB
LONG TERM...NF
AVIATION...MBS/PC
EQUIPMENT...RAB



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