Special Weather Statement, NWS Blacksburg, VA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
418 PM EDT THU AUG 9 2012

.SYNOPSIS...
A STRONG UPPER LEVEL TROUGH WILL PASS ACROSS THE GREAT LAKES OF
FRIDAY...DRAGGING A COLD FRONT ACROSS OUR AREA DURING THE
AFTERNOON AND EVENING. THUNDERSTORM ACTIVITY WITH THIS SYSTEM WILL
BE WIDESPREAD ACROSS OUR AREA...WITH A FEW STORMS BECOMING STRONG
TO SEVERE. ONCE THE COLD FRONT MOVES EAST OF THE AREA LATE FRIDAY
EVENING...HIGH PRESSURE WILL BUILD IN...BRINGING COOLER AND DRIER
AIR IN FOR THE REMAINDER OF THE WEEKEND AND THE EARLY PART OF NEXT
WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 400 PM EDT THURSDAY...

CLOUD COVER MOVING ACROSS THE AREA THIS MORNING AND AFTERNOON
PROVED HELPFUL IN LIMITING INSTABILITY...AND THEREFORE THUNDERSTORM
DEVELOPMENT ACROSS THE MOUNTAINS THIS AFTERNOON. HOWEVER WILL BE
KEEPING AN EYE ON A THUNDERSTORM COMPLEX MOVING ACROSS EASTERN
TENNESSEE THROUGH THE EARLY HALF OF THE EVENING AS SHORT RANGE
MODELS ARE EXPECTING SOME OF THIS ACTIVITY TO MOVE INTO THE NORTH
CAROLINA MOUNTAINS...AS WELL AS PARTS OF THE MOUNTAIN EMPIRE. THAT
STATED...LATEST RADAR IMAGERY INDICATES THAT THESE STORMS ARE
WEAKENING...AND CAPE VALUES ACROSS THE MOUNTAINS APPEAR TO BE
MORE MODEST COMPARED TO PREVIOUS DAYS...AND BELIEVE THAT MOST OF
THESE STORMS WILL REMAIN BELOW SEVERE LIMITS FOR THE EVENING.

FOR FRIDAY...SHOWER AND THUNDERSTORM ACTIVITY WILL INCREASE DURING
THE MORNING AND AFTERNOON FROM WEST TO EAST AS A STRONG UPPER
LEVEL TROUGH SWINGS INTO THE LOWER GREAT LAKES...BRINGING A
STRONG COLD FRONT TOWARD OUR AREA. BELIEVE THAT THUNDERSTORMS WILL
DEVELOP ACROSS THE MOUNTAINS IN BATCHES DURING THE EARLY HALF OF
THE AFTERNOON...AND WILL SOLIDIFY INTO MORE OF A LINE AS THE
TROUGH PUSHES INTO THE PIEDMONTS DURING THE EVENING. STILL LOOKING
AT THE MAIN THREAT WITH THESE STORMS TO BE LOCALLY STRONG
WINDS...HOWEVER HEAVY RAIN WILL ALSO BE POSSIBLE WHERE STORMS
BEGIN TO TRAIN.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 400 PM EDT THURSDAY...

QUITE A CHANGE IN AIRMASS COMING THIS PERIOD...BUT WILL BE DEALING
WITH LINGERING STORMS FRIDAY EVENING AS FRONT PUSHES EAST WITH
STRONG UPPER SUPPORT SHIFTING TO OUR NW. GFS SEEMS TO BE QUICKER IN
CLEARING THINGS AWAY FROM OUR AREA BY FRIDAY NIGHT WHILE THE
ECMWF/NAM/SREF HOLD ONTO THE CONVECTION A LITTLE LONGER. WENT WITH
CATEGORICAL POPS IN THE PIEDMONT FRIDAY EVENING TAPERING TO CHANCE
IN THE WEST...THEN LOWER POPS TO SLIGHT/LOW CHANCE OVERNIGHT GIVEN
THAT THE UPPER SHORTWAVE/TROUGH REMAINS WEST OF US INTO SATURDAY.

THE NEXT SHORTWAVE PIVOTS ACROSS THE CENTRAL APPALACHIANS INTO THE
MID ATLANTIC SAT AFTERNOON. THIS MAY KEEP THE THREAT OF SHOWERS OR
ISOLATED STORMS GOING IN THE EAST WITH COOL POOL ALOFT. 8H TEMPS
COOL TO +14C...SO WITH SOME CLOUD COVER FROM THE COLDER AIR
ALOFT...LOOK FOR HIGHS IN THE 70S MTNS TO MID 80S OUT EAST.

DRIER AIR WILL FINALLY SEEP IN FROM THE NW SAT NIGHT INTO SUNDAY
WITH DEWPOINTS DROPPING INTO THE UPPER 40S/LOWER 50S IN THE HIGHER
ELEVATIONS WITH MID 50S VALLEYS. THE PIEDMONT COULD SEE SOME 50S
DEWPOINTS BUT HARD TO DISPLACE THE HUMID AIRMASS ACROSS THE
CAROLINAS AS THE FLOW ALOFT STAYS WSW.

FOR LOWS SAT NIGHT WENT WITH LOCAL MOS WHICH GIVES LOWER TO MID 50S
MTNS TO LOWER 60S EAST.

SUNDAY...THE SFC FLOW BACKS AROUND TO THE WSW AGAIN AND WILL SEE
TEMPS START TO CREEP UP WITH MORE SUNSHINE. HEIGHTS/8H TEMPS
INCREASE AGAIN...SO LOOKING AT HIGHS GETTING BACK TOWARD 80 MTNS AND
MID TO UPPER 80S EAST.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 400 PM EDT THURSDAY...

DRIER AIRMASS WILL BE DISPLACED DURING THIS PERIOD AS THE FRONT FROM
THE SHORT TERM PERIOD STALLS ACROSS THE CAROLINAS/TN VALLEY THEN
SHIFTS SLOWLY NORTH BY TUESDAY AS ANOTHER WAVE OF LOW PRESSURE
SHIFTS ACROSS IT FROM THE LOWER MISSOURI VALLEY INTO THE VA
TIDEWATER FROM MON-TUE. THIS FRONT WILL BE CLOSE ENOUGH THAT
SHOWER/TSRA CHANCES INCREASE AGAIN BY TUESDAY. ONCE THE
SHORTWAVE/ASSOCIATED SFC LOW PASS TUESDAY AFTERNOON...WEAK HIGH
PRESSURE WILL PUSH THE FRONT BACK SOUTH INTO THE GA/SC BY WEDNESDAY
AND THE AIRMASS DRIES OUT SOME...BUT THE UPPER TROUGH IS NOT AS DEEP
AS THIS WEEKENDS. OVERALL...THE TEMPS NEXT WEEK WILL AVERAGE
80S/LOWER 90S FOR HIGHS AND 60S FOR LOWS.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
AS OF 215 PM EDT THURSDAY...

MID AND HIGH CLOUDS HAVE SO FAR HELPED TO DELAY THE ONSET OF
AFTERNOON SHOWERS AND THUNDERSTORMS..HOWEVER A BREAK IN THE CLOUD
COVER ENTERING WESTERN VIRGINIA IS ALLOWING FOR STRONGER CU
DEVELOPMENT...AND SHOULD NOT BE LONG BEFORE POP UP SHOWER AND
THUNDERSTORM ACTIVITY MAKES ITS WAY NEAR BLF AND LWB. AS
SUCH...HAVE ADDED VCTS INTO THE TAFS FOR THESE TWO AIRPORTS FOR
THE 09/20Z TO 10/00Z TIMEFRAME...WHILE BELIEVE COVERAGE FURTHER
EAST WILL BE TOO ISOLATED TO MAKE MENTION AT OTHER AIRPORTS.
WEATHER FORECAST MODELS APPEAR IN DECENT AGREEMENT THAT THE
APPROACHING SHORTWAVE DISTURBANCE/THUNDERSTORM COMPLEX ACROSS
TENNESSEE WILL HOLD MAINLY IN THE NORTH CAROLINA MOUNTAINS AND
POSSIBLY ENTER VIRGINIA JUST SOUTH OF BLF...BEFORE WEAKENING.

OVERNIGHT...MID AND HIGH CLOUDS WILL MAKE THE DIFFERENCE AS TO HOW
MUCH FOG DEVELOPS ACROSS THE AREA. AT THIS POINT...WILL EXPECT
SCATTERED TO BROKEN MID AND HIGH CLOUDS TO LINGER ACROSS THE
AREA...HELPING TO REDUCE THE AMOUNT OF FOG WHICH DEVELOPS...ALTHOUGH
HIGHER CLOUDS MAY THIN RIGHT AROUND SUNRISE...MAKING FOR A BRIEF
PERIOD OF DENSE FOG BEFORE DISSIPATING WITH DAYTIME HEATING.

SHOWER AND THUNDERSTORM ACTIVITY WILL INCREASE LATE FRIDAY MORNING
AND EARLY AFTERNOON AS A DEEP UPPER LEVEL TROUGH APPROACHES THE
AREA...WITH AN ASSOCIATED COLD FRONT ENTERING THE WESTERN PART OF
THE FORECAST AREA TOWARD THE END OF THE TAF PERIOD. WILL BE LOOKING
AT A FEW STRONG STORMS TO START THE AFTERNOON...AND EXPECT THAT
THESE STORMS WILL FORM INTO A LINE JUST AHEAD OF THE COLD FRONT AS
IT ENTERS THE PIEDMONT REGION DURING EARLY EVENING. THUNDERSTORM
ACTIVITY IS EXPECTED TO END ACROSS THE AREA AS THE FRONT EXITS TO
THE EAST DURING LATE EVENING...AT WHICH POINT DRIER AIR ASSOCIATED
WITH HIGH PRESSURE WILL RESULT IN VFR CONDITIONS HEADING INTO THE
EARLY PART ON NEXT WEEK.

&&

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

&&

SYNOPSIS...JH/NF
NEAR TERM...NF
SHORT TERM...WP
LONG TERM...WP
AVIATION...JH/NF

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
437 PM EDT THU AUG 9 2012

NCZ003>006-020-VAZ011-013-014-016>020-022>024-032>035-043>047-058-
059-WVZ042>045-102045-
SURRY-STOKES-ROCKINGHAM-CASWELL-YADKIN-GILES-PULASKI-MONTGOMERY-
CARROLL-FLOYD-CRAIG-ALLEGHANY VA-BATH-ROANOKE-BOTETOURT-ROCKBRIDGE-
PATRICK-FRANKLIN-BEDFORD-AMHERST-HENRY-PITTSYLVANIA-CAMPBELL-
APPOMATTOX-BUCKINGHAM-HALIFAX-CHARLOTTE-MERCER-SUMMERS-MONROE-
GREENBRIER-
437 PM EDT THU AUG 9 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL NORTH
CAROLINA...NORTHWEST NORTH CAROLINA...CENTRAL VIRGINIA...SOUTH
CENTRAL VIRGINIA...SOUTHWEST VIRGINIA...WEST CENTRAL VIRGINIA AND
SOUTHEAST WEST VIRGINIA.

.DAY ONE...TONIGHT.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER LOW AT THIS TIME.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FRIDAY AFTERNOON
AND EVENING AS BANDS OR CLUSTERS OF THUNDERSTORMS DEVELOP AND
MOVE EAST AHEAD OF A STRONG COLD FRONT. DAMAGING WINDS WILL BE THE
PRIMARY THREAT WITH VERY HEAVY RAINFALL ALSO LIKELY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

NCZ001-002-018-019-VAZ007-009-010-012-015-102045-
ASHE-ALLEGHANY NC-WATAUGA-WILKES-TAZEWELL-SMYTH-BLAND-WYTHE-GRAYSON-
437 PM EDT THU AUG 9 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHWEST NORTH CAROLINA AND
SOUTHWEST VIRGINIA.

.DAY ONE...TONIGHT.

SLOW MOVING THUNDERSTORMS WITH HEAVY RAINFALL COULD LEAD TO
LOCALIZED FLASH FLOODING LATE THIS AFTERNOON AND THIS EVENING.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FRIDAY AFTERNOON
AND EVENING AS BANDS OR CLUSTERS OF THUNDERSTORMS DEVELOP AND
MOVE EAST AHEAD OF A STRONG COLD FRONT. DAMAGING WINDS WILL BE THE
PRIMARY THREAT WITH VERY HEAVY RAINFALL ALSO LIKELY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
215 PM EDT THU AUG 9 2012

VAZ009-012-015-091845-
GRAYSON VA-SMYTH VA-WYTHE VA-
215 PM EDT THU AUG 9 2012

...A STRONG THUNDERSTORM WILL AFFECT GRAYSON...SMYTH AND WYTHE
COUNTIES...

AT 214 PM EDT...A STRONG THUNDERSTORM WAS LOCATED OVER TROUTDALE...
MOVING NORTHEAST AT 10 MPH.

WIND GUSTS TO 40 MPH AND SMALL HAIL ARE POSSIBLE WITH THIS STORM.

THIS STORM WILL BE NEAR SUGAR GROVE AROUND 235 PM...MOUNT ROGERS
NATIONAL RECREATION AREA AROUND 240 PM AND FLATRIDGE AROUND 245 PM.

LAT...LON 3703 8118 3682 8100 3681 8101 3682 8103
      3680 8104 3676 8100 3674 8100 3658 8143
      3658 8152 3672 8160

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BLACKSBURG VA
254 PM EDT THU AUG 09 2012

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0200 PM     HAIL             5 N EAST BEND           36.29N 80.52W
08/08/2012  E1.00 INCH       SURRY              NC   PUBLIC

            QUARTER SIZE HAIL...HAIL LASTED FOR ABOUT 30 MINUTES

0200 PM     HAIL             5 SSW PILOT MOUNTAIN    36.31N 80.51W
08/08/2012  E1.00 INCH       SURRY              NC   PUBLIC

            QUARTER SIZE HAIL...HAIL LASTED FOR ABOUT 15 MINUTES

0210 PM     HAIL             5 SSW PILOT MOUNTAIN    36.32N 80.52W
08/08/2012  E1.00 INCH       SURRY              NC   PUBLIC

            QUARTER SIZE HAIL...HAIL LASTED FOR ABOUT 20 MINUTES

&&

PW

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
342 PM EDT THU AUG 9 2012

NCZ001-018-092015-
ASHE NC-WATAUGA NC-
342 PM EDT THU AUG 9 2012

...A STRONG THUNDERSTORM WILL AFFECT ASHE AND WATAUGA COUNTIES...

AT 339 PM EDT...A STRONG THUNDERSTORM WAS LOCATED 5 MILES WEST OF
BOONE...MOVING NORTHEAST AT 15 MPH.

WIND GUSTS TO 40 MPH AND PEA-SIZED HAIL ARE POSSIBLE WITH THIS STORM.
VERY HEAVY RAIN WILL FALL FROM THIS STORM...AND WILL CAUSE WATER TO
POND ON ROADS AND QUICKLY FILL ROADSIDE DITCHES AND SMALL STREAMS.

THIS STORM WILL BE NEAR LOVILL AROUND 350 PM...BOONE AROUND 355 PM...
SILVERSTONE AROUND 405 PM...SANDS AROUND 410 PM AND MEAT CAMP AROUND
415 PM.

LAT...LON 3619 8189 3635 8175 3635 8173 3636 8173
      3643 8167 3629 8146 3612 8167 3611 8179
      3614 8183 3616 8183 3619 8185

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
452 PM EDT THU AUG 9 2012

NCZ018-092145-
WATAUGA NC-
452 PM EDT THU AUG 9 2012

...A STRONG THUNDERSTORM WILL AFFECT WATAUGA COUNTY...

AT 448 PM EDT...A STRONG THUNDERSTORM WAS LOCATED OVER BLOWING
ROCK...MOVING NORTH AT 15 MPH.

WIND GUSTS TO 40 MPH AND PEA-SIZED HAIL ARE POSSIBLE WITH THIS STORM.
VERY HEAVY RAIN WILL FALL FROM THIS STORM...AND WILL CAUSE WATER TO
POND ON ROADS AND QUICKLY FILL ROADSIDE DITCHES AND SMALL STREAMS.

THIS STORM WILL BE NEAR AHO AROUND 500 PM...BOONE AROUND 510 PM...
LOVILL AROUND 515 PM...SANDS AROUND 520 PM...SILVERSTONE AROUND 530
PM AND MEAT CAMP AROUND 535 PM.

LAT...LON 3635 8184 3636 8179 3635 8177 3635 8173
      3638 8173 3639 8172 3635 8164 3627 8156
      3611 8160 3612 8171 3611 8181 3617 8184