Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 200536
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
136 AM EDT MON OCT 20 2014

.SYNOPSIS...
THE CENTER OF AN AREA OF HIGH PRESSURE WILL MOVE OVER...AND THEN
EAST OF THE REGION OVERNIGHT. A DEEPENING TROUGH OF LOW PRESSURE
WILL APPROACH THE AREA ON MONDAY...CROSS THE REGION ON
TUESDAY...AND THEN STALL AND TRANSITION INTO AN UPPER LOW
PRESSURE SYSTEM ACROSS THE MID-ATLANTIC REGION BY WEDNESDAY. FOR
OUR REGION THIS SERIES OF EVENTS WILL RESULT IN INCREASED CHANCES
OF SHOWERS...ESPECIALLY ACROSS THE MOUNTAINS AND GUSTY NORTHWEST
WINDS.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 100 AM EDT MONDAY...

MADE SOME MINOR ADJUSTMENTS IN TEMPERATURES AND LOW TEMPERATURES
FOR THIS MORNING. SLOWED THE ADVANCE EAST OF THE HIGH CLOUDS WITH
DRY AIRMASS ACROSS OUR REGION. FREEZE WARNINGS AND FROST
ADVISORIES REMAIN IN EFFECT UNTIL 9 AM THIS MORNING.

AS OF 1035 PM EDT SUNDAY...

GIVEN QUICK TEMP FALLS ACROSS THE WEST INCLUDING THE NW NC
MOUNTAINS HAVE GONE AHEAD AND INCLUDED ALL OF GREENBRIER COUNTY
WITHIN THE FREEZE WARNING AS WELL AS TAZEWELL COUNTY. ALSO
INCLUDING MERCER CTY ALONG WITH GRAYSON...ASHE AND WATAUGA INTO
THE FROST ADVISORY SINCE MOST CIRRUS TO THE WEST APPEAR TO BE
FADING WITH WINDS REMAINING QUITE LIGHT. OTRW OTHER THAN LOWERING
TEMPS FEW OTHER CHANGES.

PREVIOUS DISCUSSION AS OF 815 PM EDT SUNDAY...

MAIN CONCERN CONTINUES WITH EXTENT OF FROST/FREEZE POTENTIAL
OVERNIGHT GIVEN VERY DRY AIR IN PLACE PER 00Z RAOB AND SURFACE
HIGH PRESSURE BUILDING ACROSS. THIS HAS ALREADY ALLOWED A QUICK
DROP IN EVENING TEMPS AND EXPECT READINGS TO CHASE THE DEWPOINT
ESPCLY VALLEYS AND OUTLYING AREAS FOR MUCH OF NIGHT. HOWEVER
APPROACH OF HIGH CLOUDS FROM THE WEST OF CONCERN IN CAUSING
READINGS TO STEADY OUT SOME MOUNTAINS WHILE THINKING LESS OUT EAST
WHERE THE AXIS OF THE RIDGE WILL END UP OVERNIGHT. MIXING ALSO TO
INCREASE ON THE RIDGES AS WARM ADVECTION QUICKLY PICKS UP ALOFT
MAKING THINGS TRICKY FOR COVERAGE OF FROST OR FREEZING CONDITIONS
ACROSS MANY OF THE COUNTIES. ACTUALLY THINK PARTS OF THE EAST HAVE
THE BEST SHOT AT SEEING MORE FROST DESPITE DRYNESS SO ADDED A FEW
MORE COUNTIES TO THE ADVISORY WHILE KEEPING ROANOKE AND BLUEFIELD
OUT WITH MORE PATCHY VALLEY COVERAGE THERE. ALSO ADDED MORE FROST
INTO SOUTHSIDE VA AS WELL AS THE HIGHER VALLEYS ACROSS THE NW
NORTH CAROLINA MOUNTAINS. OTRW LITTLE CHANGE TO THE HEADLINES WEST
OF THE BLUE RIDGE WHERE MAY ACTUALLY SEE READINGS ON THE RIDGES
RISE LATE. THUS BUMPED UP LOWS AT ELEVATION WHILE LOWERING VALLEYS
WHERE SOME BRIEF 20S POSSIBLE.

ON MONDAY...ANY FROST WILL QUICKLY MELT AFTER SUNRISE. SOUTHWEST
WINDS WILL START TO INCREASE AROUND NOON...AND BE NEAR 10 MPH AT
MOST LOCATIONS BY THE AFTERNOON. HIGH LEVEL CLOUD COVER WILL BE ON
THE INCREASE DURING THE AFTERNOON FROM WEST TO EAST ACROSS THE
REGION WITH THE APPROACH OF THE UPPER TROUGH. WE ARE EXPECTING
SOME ISOLATED SHOWERS ACROSS THE MOUNTAINS BY THE LATE AFTERNOON.
COVERAGE MAY BE SCATTERED OVER SOUTHEAST WEST VIRGINIA. HIGHS ON
MONDAY WILL RANGE FROM THE UPPER 50S TO LOWER 60S ACROSS THE
MOUNTAINS WITH MID TO UPPER 60S COMMON ACROSS THE PIEDMONT.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 200 PM EDT SUNDAY...

SHOWER ACTIVITY WILL INCREASE MONDAY NIGHT ACROSS THE MOUNTAINS AS
ANOTHER WEAK UPPER LEVEL DISTURBANCE PASSES ALONG THE APPALACHIAN
CHAIN IN ADVANCE OF OUR NEXT COLD FRONT. SHOWERS WILL INITIALLY KICK
OFF IN THE MOUNTAINS DURING THE EVENING...WITH SOME OF THIS ACTIVITY
THEN PASSING EAST ACROSS THE PIEDMONT BY MIDNIGHT. THE SOUTHWESTERLY
WIND FLOW AND INCREASED CLOUD COVER WILL MAKE FOR WARMER OVERNIGHT
TEMPERATURES COMPARED TO SUNDAY NIGHT...WITH LOWS GENERALLY HOLDING
IN THE 40S MOST LOCATIONS...ALTHOUGH A FEW OF THE HIGHER RIDGES WILL
REMAIN IN THE LOW 50S.

WITH THE PASSAGE OF THE UPPER LEVEL DISTURBANCE LATE MONDAY NIGHT...
WINDS WILL SHIFT WESTERLY AND MORE DOWNSLOPE. THIS WILL CAUSE SHOWER
ACTIVITY TO BRIEFLY DIMINISH FOR MUCH OF THE AREA...UNTIL THE COLD
FRONT BEGINS TO ENTER AROUND SUNRISE TUESDAY. WINDS WILL SHIFT
NORTHWESTERLY BEHIND THE FRONT...WITH THE FLOW OFF THE GREAT LAKES
BRINGING LOW LEVEL MOISTURE THAT WILL ALLOW UPSLOPE RAIN SHOWERS TO
DEVELOP ALONG OUR WESTERN RIDGES...AND SPILL INTO THE PIEDMONT
DURING THE AFTERNOON. SHOWER ACTIVITY WILL BE MOST WIDESPREAD DURING
THE AFTERNOON...AND WILL THEN GRADUALLY BEGIN TO DIMINISH FROM EAST
TO WEST DURING THE EVENING...WITH ONLY RESIDUAL SHOWERS REMAINING
ACROSS SOUTHEAST WEST VIRGINIA AND THE MOUNTAIN EMPIRE TUESDAY
NIGHT. 850 MB TEMPERATURES WILL FALL BELOW FREEZING OVERNIGHT...SO
MAY SEE A FEW SNOWFLAKES MIXED IN WITH THE RAIN BEFORE TEMPERATURES
WARM AGAIN WEDNESDAY MORNING.

WINDS WILL REMAIN OUT OF THE NORTHWEST ON WEDNESDAY THANKS TO UPPER
LEVEL LOW PRESSURE DRIFTING ACROSS NEW ENGLAND. HOWEVER...SHOWERS
WILL FINALLY COME TO AN END...WITH CLEARING SKIES...AS SURFACE HIGH
PRESSURE BUILDS IN FROM THE WEST

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 215 PM EDT SUNDAY...

EXPECT A PERIOD OF MOSTLY CLEAR SKIES FOR THE SECOND HALF OF THE
WEEK AS HIGH PRESSURE RESIDES OVER THE LOWER OHIO RIVER VALLEY...
MAINTAINING A LIGHT NORTHWESTERLY WIND FLOW ACROSS OUR AREA. MAIN
CONCERNS THROUGH THE PERIOD WILL BE POCKETS OF FROST IN SOME OF THE
DEEPER MOUNTAIN VALLEYS THURSDAY NIGHT AS WINDS DECOUPLE...AND
POSSIBLY RIVER VALLEY FOG FRIDAY AND SATURDAY NIGHTS. TEMPERATURES
WILL GO THROUGH A GRADUAL WARMING TREND TOWARDS THE WEEKEND AS UPPER
LEVEL LOW PRESSURE MOVES AWAY FROM THE AREA.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 130 AM EDT MONDAY...

SURFACE HIGH PRESSURE WILL MOVE OVER THE CENTRAL APPALACHIANS
OVERNIGHT AND TO THE COAST OF VIRGINIA AND NORTH CAROLINA
LATER THIS MORNING. SURFACE WINDS WILL REMAIN LIGHT OVERNIGHT
INTO MONDAY MORNING. THIN CIRRUS WILL SPREAD IN FROM THE WEST
THIS MORNING...AND COMBINED WITH VERY DRY AIR IN THE LOWER LEVELS
PREVENTING ANY FOG FROM FORMATION IN TYPICAL FAVORED VALLEYS...SO
VFR CONDITIONS WILL CONTINUE INTO THIS MORNING. A LIGHT COATING
OF FROST IS POSSIBLE ON PARKED AIRCRAFT EXPOSED TO THE ELEMENTS
OVERNIGHT INTO THIS MORNING...ESPECIALLY IN THE MOUNTAINS OF
SOUTHWEST VIRGINIA AND SOUTHEAST WEST VIRGINIA.

AS THE HIGH SHIFTS EAST TODAY AND DAYTIME HEATING
BEGINS...SOUTHWEST FLOW WILL START TO INCREASE IN ADVANCE OF OUR
NEXT APPROACHING UPPER TROUGH. OCCASIONAL CIRRUS WILL STILL DRIFT
ACROSS THE REGION INITIALLY...AND THEN BY AFTERNOON AN INCREASE IN
SOME MID LEVEL CLOUDS CAN BE EXPECTED IN THE FAR WEST. STILL VFR
CONDITIONS. THERE IS SOME HINT OF VERY LIGHT SHOWERS OR SPRINKLES
WITH AN UPPER LEVEL WAVE AHEAD OF THE SURFACE FRONT SNEAKING INTO
THE WESTERN SLOPES OF THE APPALACHIANS BY LATE AFTERNOON OR
EVENING. ANY SCATTERED SHOWERS ARE LIKELY TO HOLD OFF AT THE
SOUTHEAST WEST VIRGINIA AIRPORTS UNTIL MONDAY NIGHT. EVEN SO...A
VERY LOW PROBABILITY OF RESULTING IN SUB-VFR CONDITIONS.

HIGH CONFIDENCE IN CEILING...VISIBILITIES AND WIND FORECASTS
DURING THE TAF PERIOD.

EXTENDED AVIATION DISCUSSION...

AN UPPER LEVEL TROUGH WILL CROSS THE AREA TUESDAY MORNING AND
DEEPEN INTO A NEARLY STATIONARY CLOSED LOW OVER THE MID-ATLANTIC
REGION BY WEDNESDAY. THE SYSTEM WILL MAKE SLOW MOVEMENT NORTHEAST
THROUGH THURSDAY. FOR OUR REGION...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. MVFR CLOUDS WILL ALSO 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 LIKELY BE REPLACED BY AN UPPER LEVEL RIDGE BY
FRIDAY OR SATURDAY...FOR DRY AND WARM CONDITIONS.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR VAZ009>015-
     018>020-023-024-034-035-045>047.
     FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR VAZ007.
NC...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NCZ001-018.
WV...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR WVZ042>044.
     FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR WVZ507-508.

&&

$$
SYNOPSIS...DS
NEAR TERM...DS/JH/KK
SHORT TERM...NF
LONG TERM...NF
AVIATION...DS/KK/SK



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