Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 011152
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
752 AM EDT WED OCT 1 2014

.SYNOPSIS...
BACK DOOR FRONT SINKS SOUTH INTO THE CAROLINAS BY TONIGHT BEFORE
ERODING. HIGH PRESSURE TO THE NORTH WILL AGAIN WEDGE SOUTH ALONG
THE EASTERN SLOPES OF THE APPALACHIANS THURSDAY. A STRONG COLD
FRONT ARRIVES LATER FRIDAY FOLLOWED BY MUCH COOLER AIR FOR THE
WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 730 AM EDT WEDNESDAY...

UPDATED FORECAST TO ACCOUNT FOR LACK OF PRECIP ON RADAR BUT TAKING
INTO ACCOUNT UPSTREAM SHORTWAVE AND ASSOCIATED FRONT OVER THE SRN
GREAT LAKES INTO NRN VA...AND STILL THINK SHOWERS MAY DIVE SE
TOWARD LYH/BUCKINGHAM BY MIDDAY/EARLY AFTERNOON.

NO OTHER SIGNIFICANT CHANGES MADE TO THE FORECAST.

PREVIOUS VALID DISCUSSION...

KEEPING A STRATUS DECK OVER THE PIEDMONT/FOOTHILLS OF VA INTO
PORTIONS OF NC EARLY THIS MORNING ALONG WITH FOG...LOCALLY DENSE
ESPECIALLY IN THE VALLEYS AND ON THE EDGE OF THE STRATUS.

THE MODELS ARE IN AGREEMENT IN THE BACK DOOR FRONT WITH ISOLATED TO
SCATTERED SHOWERS AFFECTING THE NRN TIER OF THE CWA THROUGH THIS
AFTERNOON...AS A COUPLE OF VORT SPOKES MOVE ACROSS. THE ISSUE THIS
MORNING WILL BE THE CLOUD COVER. THE 00Z NAM/CMC AVERAGED OUT SEEMS
TO BE A BETTER SOLUTION ON SKY COVER AND THINK THE NRN AND ERN CWA
WILL SEE BKN TO OVC SKIES EARLY THEN SOME SUNSHINE TOWARD LATER IN
THE DAY WHILE THE SW CWA STAYS MAINLY SUNNY. SOME LOW LVL
CONVERGENCE MAY ALLOW MORE CU TO FORM OVER THE SRN BLUE RIDGE IN THE
AFTERNOON AS WELL...SO HAVE A FEW MORE CLOUDS IN THE NC FOOTHILLS.

HIGHS WILL BE WARM WITH MID TO UPPER 70S MOST LOCATIONS...TO LOWER
80S OVER THE NC FOOTHILLS/PIEDMONT.

TONIGHT...THE FRONT DISSIPATES LEAVING BEHIND HIGH PRESSURE AND
SEMBLANCE OF ANOTHER WEDGE. NAM/CMC AGAIN FOCUSING MORE CLOUDS IN
THE ERN CWA OVERNIGHT. FORECAST SOUNDINGS ARE NOT AS AGGRESSIVE WITH
DZ BUT WILL KEEP SOME TOWARD MORNING IN THE EAST ALONG WITH FOG.

LOWS TONIGHT WITH NOT MUCH CHANGE IN AIRMASS WILL RANGE FROM THE
UPPER 40S ACROSS THE VALLEYS IN THE WEST WITH LOWER TO MID 50S
ELSEWHERE.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 240 AM EDT WEDNESDAY...

SURFACE RIDGE WILL BE WEDGED SOUTH ALONG THE EASTERN SLOPES OF THE BLUE
RIDGE EARLY THURSDAY LIKELY RESULTING IN AREAS OF LOW CLOUDS ALONG WITH
SOME SPOTTY DRIZZLE AND FOG. HOWEVER GUIDANCE AGAIN LESS OPTIMISTIC
ABOUT DRIZZLE GIVEN VERY SHALLOW NATURE TO THE MOISTURE AND EARLY
MORNING TIMING OF BRINGING IN THE LOW DECK. THUS TRIMMED BACK
DRIZZLE/FOG COVERAGE TO MAINLY THE BLUE RIDGE IN VIRGINIA AND POINTS
EAST EARLY ON. INCREASING SHORTWAVE RIDGING ALOFT SHOULD ACT TO BUMP
THE SURFACE RIDGE FARTHER EAST DURING THURSDAY AFTERNOON ALLOWING
MIXING TO SCOUR OUT MOST OF THE WEDGE AS WARMING ALOFT KICKS IN. THIS
SHOULD ALSO PUSH HIGHS INTO THE 75-80 RANGE WEST AND LOW/MID 80S EAST
EXCEPT COOLER NE PENDING CLOUDS.

RIDGING BOTH SURFACE AND ALOFT WILL REMAIN IN PLACE THURSDAY NIGHT
AHEAD OF THE STRONG UPSTREAM 5H TROF AND ITS ASSOCIATED COLD FRONT THAT
SHOULD REMAIN WELL TO THE WEST THROUGH EARLY FRIDAY. COULD SEE SOME
ISOLATED PRE-FRONTAL -SHRA WORK INTO THE FAR SW LATE THURSDAY NIGHT
WITH POTENTIAL FOR THE LOW LEVEL WEDGE TO REDEVELOP OUT EAST WHERE SOME
SPOTTY DRIZZLE EVEN POSSIBLE LATE. OTRW ANY LIFT PER RIDGING LOOKS TOO
WEAK TO PRODUCE MUCH SO RUNNING BASICALLY DRY WITH LOWS 50S TO LOWER
60S.

STRONG COLD FRONT APPROACHES FROM THE WEST FRIDAY BUT LOOKS TO SLOW
UPON ENCOUNTERING THE EASTERN RIDGE WHILE THE BEST DYNAMICS PASS WELL
OFF TO THE NORTH. LATEST ECMWF REMAINS THE SLOWEST GIVEN A BIT MORE
NEGATIVE TILT AS MOST OTHER SOLUTIONS BRING THE BOUNDARY INTO THE WEST
LATE FRIDAY BUT DONT CLEAR THE PIEDMONT UNTIL LATE FRIDAY NIGHT. THIS
SUGGESTS A NEED TO SLOW ONSET OF HIGHER POPS DOWN A FEW HOURS WITH THE
HIGHER LIKELY/CAT POPS OVER THE MOUNTAINS DURING THE AFTERNOON...THEN
SLOWLY WORKING/DEVELOPING EAST UPON GETTING BOOTED ALONG BY THE
APPROACH OF THE MIDWEST 5H COLD POOL/SPEED MAX. HOWEVER APPEARS SHOWERS
MAY LINGER OUT EAST WELL INTO THE OVERNIGHT WITH POPS FINALLY TAPERING
OFF IN THE PIEDMONT TOWARD DAYBREAK WHILE REDEVELOPING WESTERN RIDGES
PER INCREASING POST FRONTAL UPSLOPE. OVERALL LOW TOPPED SEVERE THREAT
LOOKS MARGINAL ALTHOUGH A SLOWER SOLUTION COULD ACT TO ENHANCE WESTERN
INSTABILITY FRIDAY AFTERNOON PER BETTER NAM CAPE VALUES. HOWEVER WIND
FIELDS ALOFT AND LAPSES APPEAR WEAKER OVER THE WEST AND STRONGER EAST
WHERE LIKELY OFFSET VIA SOMEWHAT OF A RESIDUAL WEDGE UNTIL LATE.
THEREFORE KEPT SOME THUNDER MENTION MOST SPOTS AND MORE IN LINE WITH
THE STRONGER GFS SOLUTION. SLOWER TIMING SHOULD MEAN A BOUNCE IN HIGH
TEMPS ESPCLY EAST FRIDAY WHERE AROUND 80 POSSIBLE WITH MOST OTHER SPOTS
IN THE 70S GIVEN A FEW MORE HOURS OF INSOLATION FOR NOW.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 310 PM EDT TUESDAY...

A COLD FRONT WILL BE ALONG THE EAST COAST SATURDAY MORNING WITH
DRIER COOLER AIR MOVING IN ON WEST-NORTHWEST FLOW. HIGH PRESSURE
ALONG THE GULF AND LOW PRESSURE OVER NEW ENGLAND WILL PLACE A
PRESSURE GRADIENT OVER THE AREA SATURDAY. BREEZY AND GUSTY
CONDITIONS THROUGH SATURDAY EVENING...THEN HIGH PRESSURE BUILDS
NORTH INTO THE REGION. HIGH PRESSURE WILL CONTINUE TO TRACK EAST
ALONG THE GULF OVER THE WEEKEND...SHUTTING DOWN ANY MOISTURE
RETURNING INTO THE REGION. MODELS ARE MOVING A MID LEVEL DISTURBANCE
ACROSS THE OHIO VALLEY MONDAY NIGHT INTO TUESDAY. AS THIS
DISTURBANCE APPROACHES THE AREA...IT WILL BE HARD-PRESSED TO PRODUCE
WIDESPREAD SHOWERS DUE TO A LACK OF MOISTURE RECOVERY.

TEMPERATURES WILL RUN 5F-10F COOLER THAN NORMAL OVER THE WEEKEND.
TEMPERATURES BEGIN TO MODERATE TOWARDS NORMAL MONDAY AND TUESDAY.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AS OF 738 AM EDT WEDNESDAY...

LOW STRATUS/FOG WILL LIFT TOWARD 13-15Z AT ALL SITES AND EXPECT TO
SEE VFR AT ALL SITES BY MIDDAY/LATER AT LYH AND DAN AROUND 18-19Z.

NOT REALLY SEEING A GOOD THREAT FOR SHOWERS AT THE TAF
SITES...ALTHOUGH NOT OUT OF THE QUESTION TO HAVE A SHOWER OR TWO
MOVE NEAR LYH THIS AFTERNOON.


TONIGHT...WEDGE EXPECTED TO SET UP AND LOOKING AT MVFR/IFR
CIGS/VSBYS AT LYH/DAN OVERNIGHT WITH FOG AGAIN AT BCB/LWB IN THE
IFR/LIFR RANGE LATE.

EXTENDED AVIATION DISCUSSION...

ANY FOG...LOW CLOUDS WILL START TO ERODE IN THE WEST BY 13-15Z THU
BUT COULD SEE SUB VFR CIGS OUT EAST INTO MIDDAY AT LYH...BEFORE
SCATTERING OUT.

EXPECT VFR THU AFTERNOON INTO THU NIGHT. FRONTAL BOUNDARY AND
ASSOCIATED SHOWERS TO IMPACT THE MOUNTAINS BY LATE FRIDAY MORNING
AND THE PIEDMONT IN THE AFTERNOON. SUB VFR EXPECTED IN HEAVIER
SHOWERS OR ISOLATED TSRA. HAVE SHOWERS EXITING THE MTNS BY LATE
FRIDAY EVENING AND THE PIEDMONT TOWARD DAWN SATURDAY. TIMING IS
STILL TRICKY. SATURDAY SHOULD BE CLEARING OUT IN THE PIEDMONT TO
ROANOKE/BLACKSBURG BUT UPSLOPE MVFR CIGS AT BLF/LWB MAY OCCUR INTO
SAT AFTERNOON...WITH BREEZY NW WINDS.

VFR SUNDAY WITH SW WINDS TAKING SHAPE BY AFTERNOON AHEAD OF THE
NEXT FRONTAL SYSTEM.



&&

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

&&

$$
SYNOPSIS...WP
NEAR TERM...WP
SHORT TERM...JH
LONG TERM...RCS
AVIATION...WP


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