Special Weather Statement, NWS Blacksburg, VA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
355 PM EDT FRI AUG 24 2012

.SYNOPSIS...
HIGH PRESSURE WILL BE SITUATED FROM NEW ENGLAND SOUTHWEST TO THE
SOUTHERN APPALACHIANS THROUGH THE WEEKEND...WHILE A FRONT LINGERS
OFF THE COAST OF NORTH CAROLINA. A WEAK UPPER LEVEL IMPULSE WILL
RIDE UP ALONG THE FRONT OVERNIGHT THROUGH SATURDAY NIGHT BRINGING
A BETTER CHANCE OF SHOWERS TO EASTERN SECTIONS INTO SUNDAY. ANOTHER
FRONT SHIFTS SOUTHEAST INTO THE REGION BY TUESDAY WELL NORTH OF
ISAAC THAT MAY BRING INCREASING MOISTURE TO THE AREA LATER IN THE
WEEK.
&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 1048 AM EDT FRIDAY...

FOG JUST ABOUT GONE WITH CU POPPING ALREADY ALONG THE SOUTHERN
BLUE RIDGE AND WESTERN GREENBRIER COUNTY. MORE OF A DUE EASTERLY
COMPONENT TODAY MIGHT ALLOW FOR MORE DEVELOPMENT INTO GRAYSON AND
SMYTH COUNTIES TODAY. TWO AREAS OF FOCUS FOR STORMS TODAY WILL BE
NW NC AND WESTERN GREENBRIER COUNTY THIS AFTERNOON. SHRTWV MOVING
DUE NORTH GENERATING A SHIELD OF VIRGA MOSTLY THROUGH CENTRAL NC.
MID CLOUDS ASSOC WITH THIS SHIELD WILL MOVE ACROSS PIEDMONT AND
SOUTHSIDE THIS AFTERNOON. MIGHT ACTUALLY BE A FEW SPRINKLES ACROSS
THOSE PARTS TODAY TOO. ELSEWHERE SHOWERS SHOULD REMAIN ISOLATED
LIKE THE PAST COUPLE OF DAYS.

AS OF 640 AM EDT FRIDAY...

MADE SOME ADJUSTMENTS TO SKY COVER AND FOG BASED ON LATEST SAT/SFC
OBS TRENDS. FOG WILL HOLD ON INTO 900 AM...THEN DISSIPATE ACROSS
THE MTNS. MAINLY SEEING SCT/BKN CS OUT EAST...BUT ENOUGH TO KEEP
50-70 PERCENT SKY COVER WITH SOME MID CLOUDS TO THE SOUTH IN NC
MOVING NWD. SLOWED DOWN ONSET OF PRECIP BUT STILL LOOKS LIKE AREAS
ALONG THE BLUE RIDGE INTO SRN WV ARE IN THE BETTER ENVIRONMENT FOR
SHOWER OR TSRA DEVELOPMENT.

PREVIOUS DISCUSSION...

THIS MORNING...DENSE FOG WILL BE AFFECTING PORTIONS OF
SOUTHEAST WEST VIRGINIA...SOUTH INTO THE NORTH CAROLINA MOUNTAINS.
THIS DUE TO WET GROUND FROM RAIN ON THURSDAY AND LIGHT EAST FLOW.
THE FOG WILL BE SLOW TO BURN OFF BUT WILL BE GONE AROUND 9-10 AM.

TODAYS FORECAST STILL LOOKS TO BE SOMEWHAT SIMILAR TO WHAT OCCURRED
THURSDAY. MODELS SHOWING BEST CONVERGENCE AND HIGHER THETA-E
SITUATED ACROSS THE WV MTNS AND SOUTHERN BLUE RIDGE. WILL KEEP THE
HIGHER POPS IN THESE AREAS WITH LOWER CHANCES BORDERING...WITH
LITTLE TO NO POPS EAST OF THE FOOTHILLS.

THE SHORTWAVE AND ASSOCIATED LOW ALONG THE COAST APPEARS TO KEEP THE
DEEPER MOISTURE ACROSS THE COASTAL AREAS TODAY WITH INCREASING CLOUD
COVER CREEPING INTO THE PIEDMONT AT TIMES. THIS SHORTWAVE PER MODEL
SOLUTIONS SHIFTS NNW INTO THE VA PIEDMONT LATE THIS EVENING AND WILL
BE CLOSE ENOUGH THAT SHOWERS MAY SHIFT TOWARD LYH/DAN AND POINTS
EAST BY DAWN SATURDAY. FOR NOW...WILL GO SLIGHT CHANCE VERY LATE
ACROSS THE EXTREME ERN EDGE OF THE FORECAST AREA. THINK THE
SHRA/TSRA IN THE WEST WILL BEGIN TO FADE ONCE AGAIN BY LATE EVENING.
WITH WEAK FLOW...STILL LOOKING AT POTENTIAL FOR ISOLATED FLOODING
PROBLEMS...ESPECIALLY IF STORMS MOVE OVER THE SAME AREA AS THURSDAY.

KEPT HIGHS SIMILAR TO THURSDAY...EXCEPT COOLER AT DANVILLE THINKING
MORE CLOUDS. NOT MUCH CHANGE FOR FRI NIGHT TEMPS EITHER WITH LOWER
TO MID 60S EAST TO MID TO UPPER 50S MOUNTAINS.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 230 PM EDT FRIDAY...

RESIDUAL UPPER VORT THAT ORIGINATED OFF THE SE COAST WILL BE SLOW TO
EXIT SAT NIGHT AND WILL LIKELY CONTINUE TO PRODUCE A FEW BANDS OF
SHRA/TSRA ESPCLY NE HALF THRU THE OVERNIGHT. MAY NEED TO GO WITH
HIGHER POPS LATER ON PENDING HOW FAST THIS FEATURE MOVES BUT FOR NOW
KEEPING MOSTLY LOW CHANCE COVERAGE. WAVE EXITS SLOWLY TO THE NORTH
SUNDAY WHILE THE LEFTOVER WEAKNESS REMAINS ACROSS THE REGION WITH
DEEPER MOISTURE STILL IN PLACE. THINK COMBO OF THIS ALONG WITH
HEATING AND WEAK SOUTH/SE FLOW WILL AGAIN SPARK MORE SHRA/TSRA
ESPCLY BLUE RIDGE AND ACROSS THE NE SECTIONS PER LATEST NAM. UPPER
TROF FINALLY EXITS BY SUNDAY NIGHT WITH SURFACE HIGH PRESSURE
WORKING IN UNDER A RIBBON OF HIGHER 5H HEIGHTS BY MONDAY. THIS
SHOULD BRING A PERIOD OF DRIER WEATHER SUNDAY NIGHT/MONDAY WITH ONLY
AN ISOLATED MOUNTAIN SHOWER POSSIBLE DUE TO HEATING/OROGRAPHICS AND
MORE SW FLOW LATER MONDAY AFTERNOON. OTRW THINKING MORE CLOUDS SAT
NIGHT...TURNING PC SUNDAY...THEN PC TO MOSTLY SUNNY ON MONDAY AS
DRIER AIR ALOFT ADVECTS IN. THIS CLDNS SHOULD KEEP TEMPS UP A BIT
SAT NIGHT AND A LITTLE COOLER...MAINLY UPPER 70S-MID 80S SUNDAY...
BEFORE 85H WARMING TO NEAR 19-20C PUSHES HIGHS WELL INTO THE 80S AND
CLOSE TO 90 SE MONDAY.
&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...

AS OF 1215 PM EDT FRIDAY...

UPPER TROF WILL CONTINUE TO DIG SE MONDAY NIGHT...WITH ITS
ASSOCIATED COLD FRONT WORKING INTO THE AREA LATER TUESDAY BEFORE
BASICALLY DISSIPATING. THIS MAY BRING AN ISOLATED SHOWER OR STORM TO
THE WEST MONDAY NIGHT WITH LOW CHANCE POPS FOR MOST OF THE AREA
TUESDAY AFTERNOON ATLHOUGH MOISTURE ALONG THE BOUNDARY LIMITED. THIS
SHOULD STILL BE NORTH OF ANY TROPICAL MOISTURE THAT WILL LIKELY BE
HEADING BACK INLAND FROM THE SE BY TUESDAY NIGHT.

AFTER TUESDAY FORECAST HIGHLY DEPENDENT UPON TRACK OF ISAAC WITH A
MORE WESTERN SCENARIO PER THE OVERNIGHT EURO BRINGING LESS SHRA AND
MORE DIURNAL SCATTERED NATURE PRECIP UNDER A MOISTENING SOUTH/SE
FLOW...WHILE AN EASTWARD TREND...PENDING THE DEGREE OF SUBSIDENCE
FARTHER NORTH...WOULD ENHANCE CONVECTION ALONG THE OLD FRONT ESPCLY
SE SECTIONS BY WED/THU PER THE GFS...AND HAVE ONLY ISOLATED POPS FOR
WEEKS END. GIVEN UNCERTAINTY IN THE DEGREE OF INTERACTION OF ISSAC
AND THE 5H TROF TO THE NORTH/NE WILL COMPROMISE AND FOLLOW CLOSE TO
THE LATEST HPC SOLUTION IN BRINGING THE REMNANT SYSTEM UP TO THE
WEST BY FRIDAY...AND THUS HAVING A SCATTERING OF CHANCE POPS EACH
DAY UNDER THE ONSHORE FLOW. TEMPS PRETTY WARM AHEAD OF THE FRONT ON
TUESDAY WITH HIGHS MOSTLY 80S...THEN COOLING WED/THU AS MOISTURE AND
SE FLOW INCREASES...BEFORE REBOUNDING BACK INTO THE 80S FRIDAY AS
DEEPER MOISTURE LIKELY STARTS TO EXIT.
&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
AS OF 136 PM EDT FRIDAY...

WIDELY SCATTERED SHOWERS WITH A FEW STORM WILL MOSTLY BUBBLE UP
ALONG THE HIGHER ELEVATIONS. OUTSIDE CHC THAT LWB/ROA/BCB GET HIT
WITH A STORM THIS AFTERNOON. AREA OF LOW PRESSURE MOVING UP THE
COAST IS SPREADING A SCT/BKN 12KFT DECK INTO LYH/DAN AT TIMES. A
FEW SPRINKLES REMAIN WELL EAST. THE MID DECK SHOULD DISALLOW STORMS
FROM FIRING AT THESE SITES UNLESS THE CLOUDS BREAK THIS AFTERNOON.
EXPECTING SIMILAR FOG AT LWB/BCB TONIGHT...TOUGH CALL WHETHER EAST
WIND WILL BE STRONG ENOUGH TO MOVE FOG INTO KBLF. WILL REALLY NEED
SOME SHOWERS NEARBY THIS EVENING TO GENERATE THE LIFR VIS/CIG OF
THIS MORNING. NOT VERY CONFIDENT ABOUT THOSE CONDITIONS HAPPENING
AGAIN TONIGHT. AS THE AREA OF LOW PRESSURE MOVES UP THE COAST
SATURDAY A SHIELD OF LIGHT TO MODERATE RAIN MAY EVENTUALLY
OVERSPREAD DAN/LYH BY SATURDAY AFTERNOON WITH MVFR CIGS.

THE UPPER TROUGH WILL REMAIN FIXED ACROSS THE AREA ALBEIT IN A
WEAKENED STATE THROUGH THE WEEKEND. THERE WILL BE A DAILY THREAT
FOR STORMS BUT ISOLATED IN COVERAGE. A COLD FRONT WILL BE CROSSING
THROUGH THE REGION ON TUESDAY WITH A BETTER CHANCE OF MORE
WIDESPREAD SHOWERS AND THUNDERSTORMS. WILL HAVE TO WATCH WHERE TS
ISAAC GOES AS THIS COULD IMPACT CONDITIONS OVER THE ENTIRE
SOUTHEAST NEXT WEEK.

&&

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

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
338 PM EDT FRI AUG 24 2012

NCZ001-002-018-VAZ007-009>012-015-WVZ042>045-251945-
ASHE-ALLEGHANY NC-WATAUGA-TAZEWELL-SMYTH-BLAND-GILES-WYTHE-GRAYSON-
MERCER-SUMMERS-MONROE-GREENBRIER-
338 PM EDT FRI AUG 24 2012

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SLOW MOVING SHOWERS AND THUNDERSTORMS CONTAINING VERY HEAVY
RAINFALL COULD RESULT IN LOCALIZED FLOODING OF SMALL STREAMS AND
POOR DRAINAGE AREAS INTO THIS EVENING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

NCZ003>006-019-020-VAZ013-014-016>020-022>024-032>035-043>047-058-
059-251945-
SURRY-STOKES-ROCKINGHAM-CASWELL-WILKES-YADKIN-PULASKI-MONTGOMERY-
CARROLL-FLOYD-CRAIG-ALLEGHANY VA-BATH-ROANOKE-BOTETOURT-ROCKBRIDGE-
PATRICK-FRANKLIN-BEDFORD-AMHERST-HENRY-PITTSYLVANIA-CAMPBELL-
APPOMATTOX-BUCKINGHAM-HALIFAX-CHARLOTTE-
338 PM EDT FRI AUG 24 2012

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
236 PM EDT FRI AUG 24 2012

VAZ009-012-015-241930-
GRAYSON VA-SMYTH VA-WYTHE VA-
236 PM EDT FRI AUG 24 2012

...A STRONG THUNDERSTORM WITH HEAVY RAIN WILL AFFECT GRAYSON...SMYTH
AND WYTHE COUNTIES...

AT 234 PM EDT...A STRONG THUNDERSTORM WITH HEAVY RAIN WAS LOCATED 7
MILES NORTH OF INDEPENDENCE...MOVING WEST AT 10 MPH.

WIND GUSTS TO 30 MPH AND SMALL 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 ELK CREEK AROUND 245 PM...COMERS ROCK AROUND
305 PM...BRIDLE CREEK AROUND 310 PM...FLATRIDGE AROUND 325 PM AND
TROUTDALE AROUND 330 PM.

LISTEN TO NOAA WEATHER RADIO OR YOUR FAVORITE MEDIA OUTLET FOR LATER
UPDATES OR POSSIBLE WARNINGS.

LAT...LON 3682 8154 3681 8104 3664 8102 3657 8138
      3658 8150

KK

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
401 PM EDT FRI AUG 24 2012

VAZ007-010-WVZ042-242100-
BLAND VA-MERCER WV-TAZEWELL VA-
401 PM EDT FRI AUG 24 2012

...SHOWERS AND ISOLATED THUNDERSTORMS WITH HEAVY RAIN WILL AFFECT
BLAND...MERCER AND TAZEWELL COUNTIES...

AT 357 PM EDT...SHOWERS AND ISOLATED THUNDERSTORMS WITH HEAVY RAIN
WERE ALONG A LINE FROM 4 MILES EAST OF MATOAKA TO ROCKY GAP TO
BLAND. THESE STORMS WERE MOVING WEST AT 10 MPH.

WIND GUSTS TO 30 MPH ARE POSSIBLE WITH THESE STORMS. VERY HEAVY RAIN
WILL FALL FROM THESE STORMS...AND WILL CAUSE WATER TO POND ON ROADS
AND QUICKLY FILL ROADSIDE DITCHES AND SMALL STREAMS.

THESE STORMS WILL BE NEAR BASTIAN AROUND 500 PM AND TIPTOP AROUND
530 PM.

LISTEN TO NOAA WEATHER RADIO OR YOUR FAVORITE MEDIA OUTLET FOR LATER
UPDATES OR POSSIBLE WARNINGS.

LAT...LON 3726 8148 3728 8142 3733 8138 3741 8133
      3742 8129 3746 8131 3749 8128 3747 8103
      3728 8099 3727 8101 3722 8098 3705 8100
      3703 8110 3703 8119 3705 8122 3703 8125
      3704 8147

KK