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000
FXUS61 KRNK 120846
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
446 AM EDT WED JUN 12 2013

.SYNOPSIS...
WEAK HIGH PRESSURE WILL BE OVER OUR AREA TONIGHT. ONE COLD FRONT
WILL MOVE SOUTH INTO WEST VIRGINIA AND NORTHERN VIRGINIA WEDNESDAY
WITH A SECOND FRONT SWEEPING THROUGH OUR AREA FROM THE WEST
THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 420 AM EDT WEDNESDAY...

REGION OF HIGHER SURFACE DEW POINTS ND MORE UNSTABLE AIR RESIDED
FROM CENTRAL ILLINOIS INTO WESTERN KENTUCKY AND TENNESSEE THIS
MORNING. SOME WARM AIR ADVECTION ON THE EASTERN EDGE OF THIS AIR
MASS MAY BE THE INITIATION POINT FOR SHOWERS AND THUNDERSTORMS
THIS MORNING. ALTHOUGH NOT SHOWING UP WELL IN THE WATER VAPOR
LOOP...THE GFS/NAM/SREF/RUC ALL PICK UP AN A SHORT WAVE OVER THE
TENNESSEE VALLEY THIS MORNING THAT MAY HELP TRIGGER THUNDERSTORMS
AS IT TRACKS INTO GEORGIA AND SOUTH CAROLINA THIS EVENING. THIS
SOLUTION WOULD KEEP THE FORECAST ARE MOSTLY DRY. AS SPC MENTIONED
IN THEIR DAY1 DISCUSSION...ENOUGH HEATING AND INSTABILITY BY THIS
AFTERNOON FOR ISOLATED THUNDERSTORMS ALONG THE LEE TROF.

OTHER HIGH RESOLUTION SHORT TERM MODELS SHOWED OTHER POSSIBILITIES
OF PRECIPITATION FOR TODAY AND TONIGHT. THE 00Z RUN OF THE LOCAL
WRF HAD TWO CLUSTERS OF SHOWERS AND THUNDERSTORMS MOVING SOUTH
THROUGH THE FOOTHILLS AND PIEDMONT...ONE THIS AFTERNOON AND THE
SECOND BATCH THIS EVENING. NSSL WRF AND OTHER MODELS HAVE LITTLE
TO NO PRECIPITATION THIS AFTERNOON. FOR NOW HAVE A SLIGHT CHANCE
FOR THE ENTIRE COUNTY WARNING AREA TODAY.

SHOWERS AND THUNDERSTORMS ALONG AND JUST AHEAD OF A STRONG COLD
FRONT APPROACH THE WESTERN COUNTY WARNING AREA LATE TONIGHT. HAVE
THE HIGHEST PROBABILITY OF SHOWERS AND THUNDERSTORMS IN SOUTHEAST
WEST VIRGINIA WELL AFTER MIDNIGHT.

STAYED ON THE WARM SIDE OF GUIDANCE FOR MAXIMUM TEMPERATURES THIS
AFTERNOON. HIGHS CLOUDS MAY BRIEFLY LIMIT HEATING THIS
MORNING...BUT STILL EXPECTING A DECENT WARMING WITH A WEST TO
SOUTHWEST DOWNSLOPE SURFACE TO 850 MB WINDS AND 850 MB
TEMPERATURES FORECAST TO REACH +21. LITTLE CHANGE NEEDED TO LOW
TEMPERATURE FORECAST FOR TONIGHT.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
AS OF 345 AM EDT WEDNESDAY...

TIMING OF COLD FRONT AND THUNDERSTORMS SIMILAR TO LAST NIGHT`S RUNS.
DON`T THINK I HAVE EVER SEEN MOMENTUM TRANSFER OF 50 KTS AT THE TOP
OF THE MIXED LAYER IN THE MIDDLE OF JUNE AROUND THESE PARTS. LLVL
WINDS FROM MODEL SOUNDINGS ARE IMPRESSIVE WITH 60 KTS RIGHT AT 5KFT.
H85 WIND SPEEDS ARE 3 TO 5 STANDARD DEVIATIONS ABV NORMAL FROM THE
GFS TO THE NAM 18Z/2P THURSDAY. H7 HEIGHTS ARE ALSO SEVERAL STANDARD
DEVIATIONS BELOW NORMAL AS THE LOW MOVES THROUGH PA. THIS SYSTEM IS
NOT RUN OF THE MILL BY ANY STRETCH. HOWEVER...THE FLIP SIDE TO
STRONG WESTERLY H85 WINDS IS THE RAIN SHADOW/DOWNSLOPING EFFECT THAT
SHOULD OCCUR ACROSS THE NEW RIVER VALLEY. THUS...KEPT THE HIGHEST
POPS ACROSS SE WEST VA AND SOUTHSIDE VA/NC PIEDMONT. WITH STEEP LLVL
LAPSE RATES AND 2K J/G OF CAPE...SHOULDN`T BE THAT TOUGH TO GET DMGG
WINDS TO THE SURFACE WITH BOWING LINE SEGMENTS. STORMS THAT DO
DEVELOP SHOULD BE MOVING VERY FAST WITH THE EVENT ENDING PERHAPS
BEFORE DARK. SPC HAS INCLUDED PRETTY MUCH THE ENTIRE CWA IN A SLT
RISK. ALSO...FAT CAPE IN THE GROWTH ZONE MAY PRODUCE LARGE HAIL TOO.

STILL THINKING STRONG STORMS ARRIVE JUST BEFORE LUNCH TIME ACROSS SE
WEST VA...JUST AFTER LUNCH ACROSS THE NEW RIVER VALLEY AND CLOSER TO
THE AFTERNOON RUSH EAST OF THE BLUE RIDGE. EVEN BEFORE ALL THIS
OCCURS...REMNANTS FROM AN MCS ACROSS THE OHIO VALLEY MAY SCRAPE THE
EXTREME NORTHERN TIER CLOSE TO 12Z/8A THURSDAY.

IMPRESSIVE CHUNK OF RELATIVELY CHILLY AIR ARRIVES WITH H85 TEMPS
DOWN TO +8C ACROSS SE WEST VA BY FRIDAY MORNING. DID GO A FEW
DEGREES BELOW THE LIKELY CLIMATOLOGICALLY STAINED GUIDANCE WHICH
COULD PUT THE COLDEST WEST VA VALLEYS IN THE UPPER 40S. GOING TO
BE A REAL STRUGGLE TO 70F FOR PARTS OF SE WEST VA FRIDAY
ESPECIALLY IF CLOUDS HOLD FOR SEVERAL HOURS. MORE RESEMBLING
FALL...WINDS MAY GUST TO 30 MPH AT TIMES BEHIND THE FRONT FRIDAY
AFTERNOON. SATURDAY MORNING STARTS OF VERY COOL WITH MODERATION
STARTING AS HIGHS ARE A FEW DEGREES WARMER THAN FRIDAY.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 300 PM EDT TUESDAY...

HIGH PRESSURE WILL TRACK FROM THE GREAT LAKES REGION FRIDAY TO OVER
THE MID ATLANTIC REGION SATURDAY. THIS RIDGE OF HIGH PRESSURE WILL
KEEP AFTERNOON TEMPERATURES NEAR NORMAL. THE NOTICEABLE DIFFERENCE
WITH THIS RIDGE WILL BE THE LOWER HUMIDITY LEVELS. THIS RIDGES
SLIDES OFF THE SOUTHEAST COAST SUNDAY...ALLOWING A WARM FRONT TO
MOVE NORTH. HEAT AND HUMIDITY WILL RETURN SUNDAY AND MONDAY...AS
WELL AS THE CHANCE FOR AFTERNOON SHOWERS AND THUNDERSTORMS.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
AS OF 125 AM EDT WEDNESDAY...

A CLUSTER OF SHOWERS AND THUNDERSTORMS MAY DEVELOP ALONG A WARM
FRONT TONIGHT OVER THE OHIO VALLEY AND MOVE INTO WEST VIRGINIA
DURING THE MORNING...THEN ACROSS THE APPALACHIANS THIS AFTERNOON.
AT THIS TIME THE CHANCE IS LOW ENOUGH TO KEEP OUT OF THE TAFS.

A FRONT WILL BRING A PERIOD OF SUB-VFR CONDITIONS TO THE AREA
LATE WEDNESDAY NIGHT AND THURSDAY MORNING...ASSOCIATED WITH AN
ORGANIZED AREA OF SHOWERS/THUNDERSTORMS. STRONG GUSTY WINDS ARE
POSSIBLE WITH THE THUNDERSTORMS.

HIGH PRESSURE WILL BUILD IN FRIDAY AND SATURDAY RESULTING IN VFR
WEATHER. COULD SEE FOG AT THE TYPICAL LOCATIONS SUNDAY MORNING...
LWB/BCB...OTHERWISE VFR. SEEING RETURN FLOW OFF THE ATLANTIC
SUNDAY WITH A FRONT MOVING INTO THE MIDWEST/GREAT LAKES. A 20
PERCENT CHANCE OF THUNDERSTORMS SUNDAY AFTERNOON IN THE AREA AS
WELL.

&&

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

&&

$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...KM
LONG TERM...RCS
AVIATION...AMS