Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 210858
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
458 AM EDT TUE OCT 21 2014

.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE AREA TODAY. FLOW BEHIND THE FRONT
WILL REMAIN GUSTY FROM THE NORTHWEST THROUGH THURSDAY BETWEEN THE
DEPARTING PARENT LOW PRESSURE SYSTEM...AND A BUILDING RIDGE ACROSS
THE CENTRAL UNITED STATES. THIS RIDGE OF HIGH PRESSURE WILL
GRADUALLY BUILD IN OUR DIRECTION...PROVIDING FOR MODERATING
TEMPERATURES AND DRY CONDITIONS HEADING INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 400 AM EDT TUESDAY...

UPPER LEVEL TROUGH AND SURFACE COLD FRONT WILL MOVE EAST TODAY INTO
TONIGHT. SURFACE COLD FRONT WILL MOVE ACROSS THE MOUNTAINS THIS
MORNING AND TRAVEL INTO THE PIEDMONT THIS AFTERNOON INTO TONIGHT.
REGIONAL WSR-88D IMAGES THIS MORNING SHOWED SCATTERED CONVECTION
ACROSS WEST VIRGINIA SOUTHWARD TO KENTUCKY MOVING EAST THIS MORNING.
INCREASED POPS FOR THIS MORNING ESPECIALLY IN THE NORTHWEST
MOUNTAINS. ANTICIPATE A RESURGENCE OF UPSLOPE SHOWERS IN THE
WEST...WITH A BIT MORE COVERAGE EAST OF THE BLUE RIDGE BY MIDDAY. A
REINFORCING PIECE OF ENERGY WILL BUILD INTO THE AREA IN THE WAKE OF
THE COLD FRONT. KEPT THE HIGHEST POPS IN THE WEST TO NORTHWEST AND
TAPER CHANCES IN THE SOUTHEAST. NORTHWEST WINDS WILL BECOME QUITE
GUSTY THIS AFTERNOON ESPECIALLY ACROSS THE HIGHER TERRAIN.  HIGH
TEMPERATURES THIS AFTERNOON WILL RANGE FROM THE LOWER 50S IN THE
NORTHWEST MOUNTAINS TO THE LOWER 70S IN THE PIEDMONT WITH DOWNSLOPE
COMPRESSIONAL WARMING IN THIS REGION. UPPER LOW WILL PIVOT DOWN INTO
THE AREA TONIGHT AND TO THE MID ATLANTIC COAST ON WEDNESDAY. PLAYED
POPS CLOSE TO THE SUPERBLEND WITH BEST CHANCE IN THE NORTHWEST
TONIGHT. LOW TEMPERATURES TONIGHT WILL GENERALLY RANGE FROM THE MID
30S IN THE MOUNTAINS TO THE MID 40S IN THE PIEDMONT.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
AS OF 415 AM EDT TUESDAY...

THROUGH THURSDAY...THE FOCUS FOR THIS PERIOD WILL BE ON A DEEP
CLOSED UPPER LOW PROGGED TO DIVE DOWN INTO THE DELMARVA
REGION...THEN SLOWLY LIFT INTO NEW ENGLAND FOR THE WEEKEND. THE
LOW WILL KEEP A PERSISTENT CYCLONIC FLOW OVER THE REGION WITH
VARIABLE CLOUD COVER...ESPECIALLY ACROSS THE MOUNTAINS...SCATTERED
LIGHT RAIN SHOWERS...AND COOL TEMPERATURES. WITH THE REGION
REMAINING ON THE WEST TO SOUTHWEST...DRIER SIDE OF THE
SYSTEM...QPF WILL BE MINIMAL...MAINLY A FEW SPRINKLES OR
HUNDREDTHS OF AN INCH NORTH OF U.S. 460...AND PERHAPS UP TO 1/4
INCH OVER THE THREE DAY PERIOD EASTERN WV MOUNTAIN UPSLOPE AREAS.
IN ADDITION...WITH A DEEP SFC LOW DEVELOPING OFF THE DELMARVA IN
ASSOCIATION WITH THE UPPER LOW...GUSTY NW WINDS WILL DEVELOP WED-
THU. SO...WHILE THE PRECIPITATION AMOUNTS WILL BE
SCANT...CONDITIONS WED-THU WILL BE FAR FROM IDEAL WITH ABUNDANT
CLOUDS...CHILLY WINDS...AND SCATTERED LIGHT RAIN SHOWERS. THE
WORST CONDITIONS WILL BE ACROSS THE MOUNTAINS...WITH BETTER
CONDITIONS...LESS CLOUDS AND WARMER TEMPERATURES...ACROSS THE NC
PIEDMONT COUNTIES.

WITH RESPECT TO WINTER WEATHER CONCERNS...THERE REALLY ARE NONE.
THERE IS A POCKET OF NEAR 0C AIR WHICH DEVELOPS ON THE BACK SIDE
OF THE UPPER LOW LATE WED INTO THU...BUT MOVES ACROSS RAIN FREE
AREAS OF EASTERN KY/EASTERN TN/FAR SW VA...AND NW NC. AT THIS
POINT...NO PRECIPITATION IS INDICATED IN THESE AREAS.
OTHERWISE...LOW-LEVEL THICKNESS VALUES ACROSS THE COLDER WESTERN
MOUNTAIN AREAS REMAIN MOSTLY IN THE 1330-1340 RANGE...MUCH TOO
WARM FOR ANY CONCERN WITH WINTER PRECIPITATION. IN ADDITION...SFC
TEMPS WILL REMAIN ABOVE FREEZING...SO HAVE NOT INCLUDED ANY WINTER
PCPN IN THE GRIDS AND REMOVED THE FEW PIXELS OF SNOW PREVIOUSLY
INDICATED ACROSS NW GREENBRIER. THE BIGGER CONCERN WITH THESE
TEMPERATURES WILL BE THE FROST/FREEZE POTENTIAL IN AREAS THAT
CLEAR...BUT TURBULENT MIXING/WIND MAY PREVENT THAT ONCE AGAIN.
NEAR NORMAL MIN TEMPS AND BELOW NORMAL MAX TEMPS ARE EXPECTED
THROUGH MID-WEEK IN NORTHERN AREAS...WITH READINGS CLOSER TO
NORMAL IN SOUTHERN AREAS WHERE MORE SUNSHINE IS EXPECTED.

FOR FRIDAY...THE MODELS HAVE BEEN AT ODDS AS TO WHAT TO DO WITH A
NORTHERN STREAM TROUGH THAT FOLLOWS IMMEDIATELY BEHIND THE CLOSED
LOW. WHILE A COUPLE OF RUNS BACK...THIS WAS SLATED TO STAY IN THE
SOUTHERN STATES...A HIGH AMPLITUDE...SLOWLY PROGRESSIVE UPPER RIDGE
THROUGH THE CENTRAL U.S. WILL KEEP THIS FEATURE FURTHER NORTH. IN
ESSENCE...IT IS SOMEWHAT OF AN ALBERTA CLIPPER...BUT HAS PRECIOUS
MOISTURE WITH WHICH TO WORK. GFS/ECMWF WANT TO GENERATE SOME -RA
WITH THIS ACROSS THE MOUNTAINS...BUT FOR NOW WILL KEEP ALL POPS
BELOW 15 PERCENT.

USED A MODEL BLEND OF MAX/MIN TEMPS THROUGHOUT THE PERIOD...MAX
TEMPS ABOUT 10 DEGREES BELOW NORMAL THROUGH MUCH OF THE WEEK...AND
MIN TEMPS NEAR NORMAL.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 445 AM EDT TUESDAY...

BENIGN...DRY WEATHER CONDITIONS EXPECTED TO DOMINATE THE REGION
THROUGH THE WEEKEND AS THE AFOREMENTIONED BROAD UPPER RIDGE DRIFTS
FROM THE CENTRAL U.S. INTO THE EASTERN U.S. THIS RIDGE WILL
EFFECTIVELY SHUT OFF ANY INFLUX OF GULF MOISTURE...ACTUALLY
SUPPRESSED WELL SOUTH OF THE GULF COAST EVEN...AND LOCK THE COLD
CANADIAN AIR WELL NORTH OF THE BORDER WITH A STRONG ZONAL FLOW
ACROSS THAT REGION. THE 850MB 0C ISOTHERM IS PROGGED TO REMAIN
MOSTLY NORTH OF THE CANADIAN BORDER THROUGH THE END OF OCTOBER.
THROUGH THE WEEKEND...850MB TEMPS ARE PROGGED TO RISE INTO THE
+12C TO +14C...SO TEMPERATURES ARE EXPECTED TO BE ABOVE
NORMAL...ESPECIALLY MAX TEMPS...WITH MIN TEMPS CREEPING TO
SLIGHTLY ABOVE NORMAL LEVELS BY SUNDAY AS WELL. SHOULD BE A
FANTASTIC WEEKEND TO VIEW THE BRILLIANT FALL FOLIAGE AROUND THE
REGION...WHICH IS AT ITS PEAK NOW IN MANY PARTS OF THE CWA AND
SURROUNDING AREAS.

&&

.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
AS OF 145 AM EDT TUESDAY...

SHORTWAVE WILL PIVOT EAST ACROSS THE REGION THIS MORNING. MVFR
CIGS ARE EXPECTED IN THE WEST WITH THE UPSLOPE FLOW AND COLD
ADVECTION. VFR CONDITIONS WILL CONTINUE IN THE EAST.

VERY LIGHT RAIN IS POSSIBLE AT BLF...LWB...AND BCB THIS MORNING.
POCKETS OF FOG ARE ALSO POSSIBLE WHERE HEAVIER RAIN HAS FALLEN.
THE TAF SITE WITH THE BEST CHANCE FOR FOG IS LWB WHERE LATEST
GUIDANCE SUGGESTING IFR/LIFR MAY BE POSSIBLE.

STRONGEST UPPER WAVE WILL NOT ARRIVE UNTIL AFTER DAYBREAK WITH
BETTER CHANCE FOR SHWRS AND LOWERING CIGS TO THE LOW END OF MVFR.
CANNOT RULE OUT BRIEF IFR IN SOME SHOWERS AT BLF AND LWB...WITH
LOWER CONFIDENCE IN THESE CONDITIONS AT BCB.

EXPECT GUSTY WEST NORTHWEST WINDS TODAY TO SLOWLY TURNING MORE
NORTHWEST BY THIS AFTERNOON AND INTO THE EVENING WITH SOME
SHOWERS CONTINUING WESTERN SLOPES.

HIGH CONFIDENCES IN CEILINGS...VISIBILITIES AND WINDS DURING THE
PERIOD.


EXTENDED AVIATION DISCUSSION...

THE UPPER LEVEL TROUGH WILL SLOW DOWN AND DEEPEN THROUGH MID WEEK
AND ONLY SLOWLY BEGIN TO SHIFT TOWARD THE NORTHEAST BY THURSDAY. THE
MAIN IMPACT WITH BE A PERSISTENT NORTHWEST GUSTY WIND AND
SCATTERED RAIN SHOWERS THAT WILL IMPACT PRIMARILY THE PREFERRED
UPSLOPE REGION OF SOUTHEAST WEST VIRGINIA INTO WED NIGHT OR EVEN
THURS MORNING. MVFR CLOUDS WILL THUS BE COMMON ACROSS THE
MOUNTAINS DURING THIS TIME PERIOD...BUT FROM ROA TO LYH TO DAN
CONDITIONS ARE LIKELY TO REMAIN VFR THROUGH THIS PERIOD. THE
PERSISTENT TROUGH WITH NORTHWEST FLOW AND LOW- LEVEL UPSLOPE
CLOUDS IN WEST WILL SLOWLY BE REPLACED BY AN UPPER LEVEL RIDGE BY
FRIDAY AND INTO THE WEEKEND...FOR DRY AND WARM CONDITIONS.

&&

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

&&

$$
SYNOPSIS...KK
NEAR TERM...KK
SHORT TERM...RAB
LONG TERM...PM/RAB
AVIATION...KK


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