Severe Thunderstorm Warning 19, NWS Blacksburg, VA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
338 PM EDT WED APR 29 2009

.SYNOPSIS...
A COLD FRONT WILL STAY SOUTH INTO NORTH CAROLINA TONIGHT...THEN
HEAD BACK NORTH AS A WARM FRONT THROUGH THE AREA THURSDAY
AFTERNOON. ANOTHER COLD FRONT ARRIVES LATE FRIDAY INTO
SATURDAY...MEANDERING AROUND THE SOUTHEAST THROUGH EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
CONVECTION FIRED UP THIS AFTERNOON ACROSS THE SOUTHWEST AS AIRMASS
REMAINS UNSTABLE HERE. THIS COMBINED WITH AN APPROACHING VORT LOBE
WILL KEEP THE THREAT OF THUNDER AROUND THROUGH LATE
AFTERNOON/EARLY EVENING...WITH SOME DEVELOPMENT EXPECTED INTO THE
PIEDMONT...BUT NOT AS NUMEROUS. SOME OF THESE STORMS WILL BE
STRONG WITH GUSTY WINDS AND SMALL HAIL...AND NOT OF THE QUESTION
TO HAVE ISOLATED SEVERE THROUGH SUNDOWN.

THIS EVENING...THE STABLE AIR OVER THE MID ATLANTIC...WILL DIVE
SOUTHWEST INTO THE REGION AS NE-E FLOW INCREASES. THE FAR
SOUTHWEST WILL REMAIN OUTSIDE THE STABLE AIR AND WILL SEE A BETTER
THREAT OF SHOWERS/ISOLATED THUNDER UNTIL MIDNIGHT.
OVERNIGHT...ONCE THE SHORTWAVE PASSES...FORCING IS SCARCE...AND
MODEL SOUNDINGS SUGGEST THAT SPOTTY LIGHT RAIN/DRIZZLE ESPECIALLY
IN THE WEDGED IN AREAS FROM THE NEW RIVER VALLEY AND HIGHLANDS
EAST TO THE PIEDMONT. SHOULD ALSO SEE SOME DENSE FOG ALONG THE
RIDGES...I.E. BLUE RIDGE PARKWAY/FANCY GAP OVERNIGHT. LOWS
TONIGHT WILL BE CLOSE TO MAV MOS.

THURSDAY...TRICKY FORECAST IN TERMS OF TEMPS...BUT MODELS
INDICATING STRONGER SOUTHWEST FLOW BY AFTERNOON TO SCOUR OUT THE
WEDGE. STILL KEEPING THE NRN/NERN CWA WITH COOLER TEMPS...BUT
BUMPED UP HIGHS ELSEWHERE...KEEPING IT JUST A TAD COOLER THAN MAV
FOR NOW. PATCHY LIGHT RAIN/DRIZZLE IN THE MORNING WILL GIVE WAY TO
MAINLY DRY WX THURSDAY AFTERNOON OVER THE EAST...WHILE AN
APPROACHING SHORTWAVE OVER THE OHIO VALLEY...AND SOME INCREASE IN
LOW LVL CONVERGENCE BRINGS THE RETURN OF ISOLATED...TO SCATTERED
THUNDERSTORMS IN THE MOUNTAINS. KEPT ISOLATED IN THE EAST AS
WELL...BUT NOT LOOKING AT MUCH.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
FAIRLY SIGNIFICANT SHORT WAVE IN NAM/GFS...ALL MODELS REALLY...TO
TRACK ACROSS THE APPALACHIANS OVERNIGHT THURS INTO FRI MORNING...AND
WHILE CONVECTIVELY INDUCED...ITS NOT A FIGMENT OF THE MODELS
IMAGINATION SINCE A CLASSIC MESOSCALE CONVECTIVE VORTEX HAS FORMED
WITH THE CONVECTIVE SYSTEM IN OKLAHOMA TODAY. HAVE TO CONSIDER THE
LIKELIHOOS OF SHWRS AND TSTORMS LASTING INTO OVERNIGHT PERIOD AS
THIS WAVE TRACKS ACROSS.  SUBSIDENCE BEHIND IT COULD ACTUALLY
SUPRESS CONVECTIVE ACTIVITY UNTIL LATER IN THE DAY WHEN BETTER
HEATING MAY KICK OF MORE OROGRAPHIC CONVECTION AND NOT AS WIDESPREAD
AS PREVIOUS DAYS. SFC FRONT AT THIS TIME STILL IN THE MIDWEST
STATES...BUT SW FLOW AND STILL DECENT LOW LVL MSTR SHOULD BE ENOUGH.
HAVE LOWERED THE POPS SOMEWHAT FOR FRIDAY DAYTIME THOUGH...
ESPECIALLY IN THE PIEDMONT...GIVEN SUSPECTED SUBSIDENCE. TROUBLE
IS...ANOTHER WAVE ON ITS HEELS BY LATE IN THE DAY MAY STILL PLAY A
ROLE IN TRIGGERING AFTERNOON CONVECTION...BUT ORIGINS AND TIMING OF
THIS WAVE MORE QUESTIONABLE.

FRONT STILL ON TRACK TO ARRIVE EARLY SAURDAY BUT PERHAPS TRENDING A
LITTLE SLOWER. HAVE KEPT POPS LOW FOR OVERNIGHT...BUT LIKELY IN THE
WEST FOR SATURDAY AS FRONT PUSHES THROUGH PROBABLY EARLY IN THE DAY.
FRONT WONT GET TOO FAR AS IT BEGINS TO TILT OVER FASTER TO THE
NORTH..BECOMING EAST-WEST ORIENTED BY LATE IN THE DAY AND STILL IN
OR JUST SOUTH OF CWA BY SAT EVENING SUCH THAT STILL CANT RULE OUT
SOME CONVECTION EVEN JUST NORTH OF IT...AT LEAST INTO THE EVENING.

AS FAR AS TEMPERATURES ARE CONCERNED...FRIDAY WENT WITH WARMER MET
GUIDANCE GIVEN BREAK BETWEEN S/WV TO THE EAST AND FRONT STILL TO THE
WEST...UNDER GOOD SW FLOW. PERHAPS A LITTLE MORE SUN THAN ON OTHER
DAYS. THEN COOLER THAN THE MAV GUIDANCE FOR SAT GIVE FRONTAL
BOUNDARY DRAPED ACROSS AREA WITH LOTS OF CLOUDS AND SHWRS/TSTMS.
CLOSE TO MILD OVERNIGHTS WITH PLENTY OF CLOUDS AND DEW PTS REMAINING
IN 50S.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
DONT SEE ANY SIGNIFICANT CHANGES TO THE CONTINUED UNSETTLED PATTERN
THROUGH MID NEXT WEEK. FLAT RIDGE WILL CONTINUE OVER THE AREA
KEEPING FAIRLY MILD TEMPERATURES IN PLACE...BUT SERIES OF SHORT
WAVES WILL EJECT OUT OF THE SRN U.S. IN SPLIT FLOW PATTERN...HELPING
TO KEEP MOISTURE IN THE AREA AND A SFC BOUNDARY FROM STRAYING TOO
FAR FROM THE CENTRAL APPALACHIAN REGION AS WELL. ECMWF WHICH HAS
SLIGHTLY HIGHER AMPLITUDE ENERGY COMING OUT OF SRN BRANCH IS
CONSENSUS SOLN AT THIS TIME...AND DOES SUGGEST THAT BOUNDARY WILL
NOW TRY TO LIFT NORTH OF AREA BY TUES AND INTO WED...BUT BEFORE THAT
MAY REMAIN SOUTH OF REGION WITH WEAK DAMMING SCENARIO. APPEARS THAT
PRETTY STRONG WAVE COULD APPROACH ALONG BOUNDARY ON SUNDAY...SO
TRENDED UPWARD A BIT WITH POPS TO CHOW HIGH CHC IN WEST. DEEPER
AMPLITUDATE WAVE BY MONDAY MAY SLOW DOWN BEST CHANCES TO LATE IN THE
DAY...BUT THIS IS WHERE IT GETS MUCH TRICKIERR TO TIME THESE WAVES.
AM REALLY JUST PLAYING CHC POPS ALL THE WAY THROUGH...WITH GENERALLY
BETTER CHANCES IN THE MTNS WITH SW TO WEST FLOW. TEMPS COULD BE
COOLER THAN WE CURRENT HAVE THEM SUN/MON BECAUSE OF THIS...BUT AM
SUGGESTING WARMING TUES/WED AS BOUNDARY LIFTS NORTH...AND ALSO MORE
SCT NATURE OF CONVECTION BY NEXT WED...PERHAPS EVEN A REAL BREAK. SO
DID LOWER POPS A BIT BY NEXT THEN. ALL IN ALL...NO MAJOR CHANGES TO
MEDIUM RANGE PERIOD FROM PREVIOUS FORECAST...WITH EXTENSION OF
PRECIP CHANCES INTO AT LEAST WED UNTIL WE SEE A MAJOR PATTERN CHANGE
COMING. THERE COULD ACTUALLY BE A DRY DAY IN THE MID PART OF NEXT
WEEK...BUT CANT PIN POINT IT JUST YET.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
BACKDOOR FRONT ALREADY WELL INTO NC WITH EASTERLY FLOW. CIGS ARE
GOING TO STAY VFR THROUG THE AFTERNOON FROM ROA-LYH-DAN
SOUTH...WITH MVFR TO OCNL IFR CIGS OVER THE LWB CORRIDOR INTO THE
VA HIGHLANDS. SHOWERS AND SCATTERED THUNDERSTORMS WILL DEVELOP
FURTHER EAST INTO THE BLUE RIDGE...AND PIEDMONT BY LATE THIS
AFTERNOON. HOWEVER...COVERAGE OF THUNDER WILL BE SUCH THAT I WILL
NOT INCLUDE IN TAFS EXCEPT ADD CB TO DANVILLE...AS STABLE AIR WILL
SINK SOUTH TO THE ROA-LYH AREA BY THE TIME SHOWERS MAKE IT IN.

BLF/LWB WILL SEE CIGS IN THE MVFR TO IFR RANGE LATER THIS
EVENING...WITH THE EASTERLY FLOW DROPPING THE REST OF THE TAF
SITES DOWN TO IFR/LOW END MVFR OVERNIGHT. KEPT ROANOKE JUST ABOVE
IFR...BUT SOME SUB-MVFR CIGS ARE POSSIBLE ALONG WITH VSBYS IN THE
3-5SM RANGE WITH DRIZZLE.

CIGS WILL BEGIN TO RISE IN THE BLF/LWB AREA LATE THIS PERIOD WHILE
THE AIRPORTS ALONG/EAST OF THE NEW RIVER VALLEY AND ROANOKE AREA
STAY IN THE LOW END MVFR/HIGH END IFR RANGE THANKS TO SE FLOW AND
WEDGE.

CONDITIONS SHOULD IMPROVE AT ALL LOCATIONS TOWARD THU AFTERNOON-THU
NIGHT...AS THE WEDGE BREAKS AND STRONG SW FLOW BRINGS IN WARMER
AIR AHEAD OF THE NEXT FRONT.

THE WEATHER PATTERN WILL BECOME UNSETTLED FRI-SUN AS ANOTHER
FRONT ARRIVES AND SETS UP ACROSS THE REGION.

&&

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

&&

SYNOPSIS...PM/WP
NEAR TERM...WP
SHORT TERM...SK
LONG TERM...SK
AVIATION...PM/WP

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
337 AM EDT WED APR 29 2009

NCZ001>006-018>020-VAZ007-009>020-022>024-032>035-043>047-058-059-
WVZ042>045-300745-
ASHE-ALLEGHANY NC-SURRY-STOKES-ROCKINGHAM-CASWELL-WATAUGA-WILKES-
YADKIN-TAZEWELL-SMYTH-BLAND-GILES-WYTHE-PULASKI-MONTGOMERY-GRAYSON-
CARROLL-FLOYD-CRAIG-ALLEGHANY VA-BATH-ROANOKE-BOTETOURT-ROCKBRIDGE-
PATRICK-FRANKLIN-BEDFORD-AMHERST-HENRY-PITTSYLVANIA-CAMPBELL-
APPOMATTOX-BUCKINGHAM-HALIFAX-CHARLOTTE-MERCER-SUMMERS-MONROE-
GREENBRIER-
337 AM EDT WED APR 29 2009

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...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
230 PM EDT WED APR 29 2009

VAZ007-009-010-012-013-015-016-291900-
BLAND VA-CARROLL VA-GRAYSON VA-PULASKI VA-SMYTH VA-TAZEWELL VA-
WYTHE VA-
230 PM EDT WED APR 29 2009

...THUNDERSTORMS WILL AFFECT
BLAND...CARROLL...GRAYSON...PULASKI...SMYTH...TAZEWELL AND WYTHE
COUNTIES...

AT 228 PM EDT...STRONG THUNDERSTORMS WERE ALONG A LINE FROM 5 MILES
SOUTHEAST OF BURKES GARDEN TO 7 MILES NORTHEAST OF MARION...MOVING
NORTHEAST AT 10 MPH.

WIND GUSTS TO 50 MPH AND SMALL HAIL ARE POSSIBLE WITH THESE STORMS.

THESE STORMS WILL BE NEAR COMERS ROCK AROUND 235 PM...MARION
WYTHEVILLE AROUND 245 PM AND SUITER AROUND 300 PM.

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

LAT...LON 3727 8113 3711 8114 3712 8082 3682 8087
      3667 8140 3703 8155

EXPERIMENTAL

KM

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
311 PM EDT WED APR 29 2009

VAZ012-015-291945-
GRAYSON VA-WYTHE VA-
311 PM EDT WED APR 29 2009

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

AT 310 PM EDT...A STRONG THUNDERSTORM WAS LOCATED 5 MILES SOUTH OF
SPEEDWELL...MOVING EAST AT 10 MPH.

WIND GUSTS TO 40 MPH AND PEA-SIZED HAIL ARE POSSIBLE WITH THIS STORM.

THIS STORM WILL BE NEAR CRIPPLE CREEK AROUND 335 PM AND SPRING VALLEY
AROUND 345 PM.

FOR ADDITIONAL WEATHER INFORMATION...VISIT US ON THE WEB AT
HTTP://WEATHER.GOV.

LAT...LON 3681 8124 3685 8096 3682 8097 3681 8100
      3682 8102 3681 8104 3674 8098 3669 8099
      3671 8125

EXPERIMENTAL

KM

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
407 PM EDT WED APR 29 2009

VAZ013-017-292030-
FLOYD VA-PULASKI VA-
407 PM EDT WED APR 29 2009

...A STRONG THUNDERSTORM WILL AFFECT FLOYD AND PULASKI COUNTIES...

AT 406 PM EDT...A STRONG THUNDERSTORM WAS LOCATED OVER ALLISONIA...
MOVING EAST AT 10 MPH.

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

THIS STORM WILL BE NEAR INDIAN VALLEY AROUND 430 PM.

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

LAT...LON 3688 8073 3691 8077 3698 8078 3703 8055
      3698 8053 3699 8052 3689 8048 3688 8059
      3693 8063 3690 8068 3689 8068

EXPERIMENTAL

KM

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