Severe Thunderstorm Warning 141, NWS Blacksburg, VA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
411 PM EDT FRI JUL 19 2013

.SYNOPSIS...
WEAK HIGH PRESSURE AT THE SURFACE AND ALOFT WILL MAINTAIN HOT AND
HUMID CONDITIONS INTO SATURDAY. A WEAK COLD FRONT WILL DRIFT
SOUTHEAST INTO THE AREA SATURDAY NIGHT...THEN STALL OVER OR JUST
SOUTH OF THE REGION ON SUNDAY. THE PROXIMITY OF THIS FRONT WILL
INCREASE THE THREAT FOR SHOWERS AND THUNDERS AS THE WEEKEND
PROGRESSES INTO EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 405 PM EDT FRIDAY...

STRONG DAYTIME HEATING...DIFFERENTIAL HEATING...AND LOCALIZED
FORCED ASCENT DUE TO OROGRAPHY PROVIDED AGAIN PROVIDED THE NEEDED
SUPPORT FOR CONVECTIVE DEVELOPMENT IN THE MOUNTAINS THIS
AFTERNOON. HOWEVER...CONVECTIVITY ACTIVITY HAS REMAINED LIMITED AT
BEST FURTHER EAST OVER THE PIEDMONT DUE TO THE PERSISTENCE OF A
WEAK WARM NOSE IN LOWEST 10K FEET WITH LACKLUSTER MID LEVEL LAPSE
RATES.

WEAK CORFIDI VECTORS OF LESS THAN 5 KNOTS IN ALL AREAS...AND HIGH
PRECIPITABLE WATER VALUES ON ORDER OF 1.65 INCHES HAVE RESULTED
IN OUTFLOW- AND TOPOGRAPHICALLY-DOMINATED STORMS THAT HAVE
YEILDED LOCALIZED FLASH FLOODING AND SPOTTY LOW-END SEVERE WIND
AND HAIL.

AS OF TIME OF THIS WRITING...SUFFICIENT OUTFLOW/COOL POOLS HAVE
SPREAD ACROSS MOST OF THE MOUNTAIN AREAS SUCH THAT AREAL COVERAGE
AND INTENSITY FOR THE REST OF THE AFTERNOON INTO THIS EVENING
SHOULD BE ON THE WANE. HOWEVER...AN ISOLATED SEVERE STORM IS STILL
POSSIBLE ACROSS THE PIEDMONT...WHERE THE AIRMASS HAS NOT BEEN
WORKED-OVER AND STILL REMAINS QUITE SULTRY.

LOSS OF DAYTIME HEATING AND LACK OF DYNAMIC FORCING SHOULD SEE
DEMISE OF ALL CONVECTIVE ACTIVITY BY MIDNIGHT TONIGHT IN MOST
AREAS...TO BE FOLLOWED BY DEVELOPMENT OF MOUNTAIN VALLEY FOG..WITH
PATCHY FOG IN LOW LYING AREAS OF THE PIEDMONT.

LITTLE CHANGE OF OVERALL AIRMASS ON SATURDAY SHOULD BRING A REPEAT
PERFORMANCE OF WEATHER...WITH MORNING FOG BURNING OFF/LIFTING BY
MID MORNING...TO BE FOLLOWED BY RAPID DEVELOPMENT OF TOWERING
CUMULUS IN UNCAPPED ATMOSPHERE. WIDELY SCATTERED TO NUMEROUS
THUNDERSTORMS ARE EXPECTED TO REDEVELOP IN THE MOUNTAINS
BY/AROUND NOON...SPREADING EAST INTO THE FOOTHILLS AND PIEDMONT
SHORTLY THEREAFTER AS ERRATIC CORFIDI VECTORS BECOMING MORE
WESTERLY AS UPPER RIDGE BEGINS TO BE SUPPRESSED SOUTHEASTWARD AS
GREAT LAKE TROF BEGINS TO BECOME ESTABLISHED.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 345 PM EDT FRIDAY...

UPPER TROF WELL IN PLACE OVER THE EASTERN UNITED STATES BY SATURDAY
NIGHT WITH 500 MB HEIGHTS FALLING SLIGHTLY OVER THE COUNTY WARNING
AREA ON SATURDAY NIGHT AND SUNDAY. THE UPPER JET WILL ADD SOME LIFT
ON SATURDAY NIGHT THROUGH MONDAY. IN ADDITION...LOW LEVEL
CONVERGENCE WILL INCREASE WITH THE ARRIVAL OF THE COLD FRONT ON
SUNDAY. ENOUGH LIGHT AND FORCING TO KEEP HIGHER PROBABILITY OF
PRECIPITATION IN THE FORECAST ON SUNDAY.

MID LEVEL TEMPERATURES DROP SLIGHTLY WHICH WILL LEAD TO BETTER LAPSE
RATES AND INSTABILITY OVER THE FORECAST AREA. AIR MASS WILL REMAIN
HUMID AND PRECIPITABLE WATER VALUES STAY IN 1.5 TO 2.0 RANGE. WILL
CONTINUE TO HIGHLIGHT THREAT OF HEAVY RAIN AND POTENTIAL FOR
FLOODING IN THE HAZARDOUS WEATHER OUTLOOK.

SURFACE DEW POINTS WILL REMAIN IN THE 60S AND 70S...KEEPING
OVERNIGHT TEMPERATURES MILD. PRECIPITATION AND CLOUD COVER MAY LIMIT
AMOUNT OF DAYTIME HEATING. STILL EXPECT TEMPERATURES TO BE NEAR
NORMAL.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 1140 AM EDT FRIDAY...

500 MB TROF REMAINS OVER THE EASTERN UNITED STATES THROUGH THIS TIME
FRAME. SHORT WAVE ROTATING THROUGH THE TROF WILL PERIODICALLY BRING
A COLD FRONT CLOSER TO THE FORECAST AREA. ECMWF BRINGS STRONGER
SHORT WAVE...POSSIBLY CLOSING OFF INTO THE REGION ON WEDNESDAY AND
THURSDAY. THIS WOULD BRING A COLD FRONT THROUGH THE AREA WITH THE
POTENTIAL FOR A DECENT PUSH OF DRIER AND COOLER AIR IN FOR NEXT
WEEKEND.

BUT UNTIL THEN...REGION STAYS IN THE WARM UNSTABLE AIR MASS WITH
DAILY THREAT OF AFTERNOON AND EVENING THUNDERSTORMS...OCCASIONALLY
ENHANCED IN COVERAGE BY SHORT WAVE ENERGY COMING THROUGH THE UPPER
TROF. EXPECT NEAR NORMAL TEMPERATURES THROUGH DAY 7/FRIDAY.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
AS OF 210 PM EDT FRIDAY...

MAINLY VFR FLIGHT CONDITIONS ARE EXPECTED FOR THE REST OF THIS
AFTERNOON AT ALL TERMINAL FORECAST SITES OUTSIDE OF AREAS OF
SHOWERS/THUNDERSTORMS...WHERE CONDITIONS WILL LOCALLY BE REDUCED
INTO THE LIFR RANGE IN TORRENTIAL RAIN. ACTIVITY THROUGH THE
AFTERNOON HOURS WILL BE FOCUSED ALONG THE EASTERN FLANKS OF THE
BLUE RIDGE...MAINLY SOUTH OF ROANOKE...WITH MORE ISOLATED/WIDELY
SCATTERED STORMS AND ASSOCIATED RESTRICTIONS ELSEWHERE. WITH
PRIMARY AREA OF STORMS REMAINING OUTSIDE OF TERMINAL FORECAST
SITES (KLWB...KBLF...KBCB...KROA...KLYH...KDAN)...HAVE MAINTAINED
MENTION OF VCTS AT ALL RESPECTIVE LOCATIONS...BUT WILL NOT INCLUDE
PREVAILING CONDITION UNLESS SPECIFIC STORM DIRECTLY THREATENS ANY
PARTICULAR SITE.

WITH LOSS OF DAYTIME HEATING...A MOIST GROUND...CLEARING
SKIES...AND NEARLY CALM BOUNDARY LAYER...SHOULD SEE ANOTHER NIGHT
WHERE WIDESPREAD MOUNTAIN VALLEY FOG DEVELOPS...ALONG WITH MORE
LOCALIZED FOG IN LOW LYING AREAS OF THE PIEDMONT...PRIMARILY
DRIVING AREAS SUCH AS KLWB...KBCB...AND KLYH INTO IFR/LIFR
RANGE...ALTHOUGH OTHER AREAS SUCH AS AT KBLF AND KDAN MAY TREND
THAT WAY AS WELL.

SIMILAR TO THIS MORNING...EXPECT FOG TO BURN OFF/LIFT BY 0900-1000
AM ON SATURDAY IN MOST AREAS...ONLY TO BE REPLACED BY BUILDING
CLOUDS AND REDEVELOPMENT OF SHOWERS/THUNDERSTORMS SHORTLY
BEFORE/AROUND NOON. APPROACH OF COOL FRONT FROM NORTH AND WEST
WILL PROVIDE EVEN GREATER THREAT/FOCUS FOR A MORE WIDESPREAD
COVERAGE OF STORMS BY MID-LATE AFTERNOON...ALONG WITH ASSOCIATED
FLIGHT RESTRICTIONS...AND AS IT STALLS OVER THE AREA SATURDAY
NIGHT INTO SUNDAY. PROXIMITY OF FRONT WILL MAINTAIN THREAT OF
WIDESPREAD FLIGHT RESTRICTIONS INTO AT LEAST MVFR...IF NOT IFR
RANGE...DURING THIS TIMEFRAME.

MODELS CONTINUE TO DEPICT STALLED FRONT REMAINING OVER/NEAR THE
AREA INTO EARLY NEXT WEEK...ONLY TO HAVE YET ANOTHER FRONT TO
APPROACH AND THEN STALL OVER THE AREA BY MIDWEEK. AS A
RESULT...INTRUSIONS BACK INTO THE VFR RANGE MAY BE RELATIVELY
SHORT LIVED WELL INTO NEXT WEEK...ESPECIALLY IN THE MOUNTAINS.

&&

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

&&

SYNOPSIS...WERT
NEAR TERM...WERT
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...WERT

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
536 AM EDT FRI JUL 19 2013

NCZ001>006-018>020-VAZ007-009>020-022>024-032>035-043>047-058-059-
WVZ042>045-200945-
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-
536 AM EDT FRI JUL 19 2013

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.

ISOLATED STRONG TO SEVERE THUNDERSTORMS ALONG WITH LOCALLY HEAVY
RAINFALL WILL BE POSSIBLE THIS AFTERNOON AND EVENING.

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

THUNDERSTORMS WILL BECOME MORE NUMEROUS OVER THE WEEKEND WITH THE
CONTINUED THREAT FOR ISOLATED TO SCATTERED SEVERE STORMS ALONG
WITH FLOODING FROM VERY HEAVY RAINFALL INTO EARLY NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
259 PM EDT FRI JUL 19 2013

VAZ020-192000-
BATH VA-
259 PM EDT FRI JUL 19 2013

THE NATIONAL WEATHER SERVICE IN BLACKSBURG HAS ISSUED A

* SPECIAL WEATHER STATEMENT FOR...
  NORTHEASTERN BATH COUNTY IN WEST CENTRAL VIRGINIA...

* UNTIL 400 PM EDT

* AT 255 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
  A STRONG THUNDERSTORM NEAR BURNSVILLE...MOVING TO THE EAST AT 10
  MPH.

* VERY HEAVY RAIN IS FALLING...AND WILL CAUSE WATER TO POND ON
  ROADWAYS AND QUICKLY FILL ROADSIDE DITCHES AND SMALL STREAMS.
  EXPECT FREQUENT CLOUD TO GROUND LIGHTNING WITH THIS STORM.

* LOCATIONS IMPACTED INCLUDE...
  AND BURNSVILLE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

PROLONGED HEAVY RAINFALL MAY CAUSE WATER TO FLOW OVER THE ROADWAY. DO
NOT DRIVE YOUR VEHICLE WHERE THE ROAD HAS BECOME FLOODED.

DO NOT STAY IN THE OPEN OR SHELTER UNDER TREES WHEN LIGHTNING
THREATENS. SEEK SHELTER INSIDE A STURDY BUILDING OR IN A VEHICLE.

&&

LAT...LON 3820 7957 3818 7952 3817 7951 3817 7953
      3816 7952 3815 7953 3816 7950 3817 7949
      3816 7944 3812 7967 3822 7971
TIME...MOT...LOC 1855Z 261DEG 8KT 3817 7962

MBS

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
303 PM EDT FRI JUL 19 2013

WVZ044-191930-
MONROE WV-
303 PM EDT FRI JUL 19 2013

THE NATIONAL WEATHER SERVICE IN BLACKSBURG HAS ISSUED A

* SPECIAL WEATHER STATEMENT FOR...
  SOUTHWESTERN MONROE COUNTY IN SOUTHEAST WEST VIRGINIA...

* UNTIL 330 PM EDT

* AT 259 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
  A STRONG THUNDERSTORM NEAR RED SULPHUR SPRING...MOVING TO THE EAST
  AT 10 MPH.

* VERY HEAVY RAIN IS FALLING...AND WILL CAUSE WATER TO POND ON
  ROADWAYS AND QUICKLY FILL ROADSIDE DITCHES AND SMALL STREAMS.

* LOCATIONS IMPACTED INCLUDE...
  LINDSIDE...
  AND RED SULPHUR SPRING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

PROLONGED HEAVY RAINFALL MAY CAUSE WATER TO FLOW OVER THE ROADWAY. DO
NOT DRIVE YOUR VEHICLE WHERE THE ROAD HAS BECOME FLOODED.

DO NOT STAY IN THE OPEN OR SHELTER UNDER TREES WHEN LIGHTNING
THREATENS. SEEK SHELTER INSIDE A STURDY BUILDING OR IN A VEHICLE.

&&

LAT...LON 3759 8063 3744 8063 3743 8080 3752 8080
      3753 8079
TIME...MOT...LOC 1859Z 261DEG 8KT 3747 8076

MBS

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
450 PM EDT FRI JUL 19 2013

VAZ010-WVZ042-192115-
BLAND VA-MERCER WV-
450 PM EDT FRI JUL 19 2013

THE NATIONAL WEATHER SERVICE IN BLACKSBURG HAS ISSUED A

* SPECIAL WEATHER STATEMENT FOR...
  NORTH CENTRAL BLAND COUNTY IN SOUTHWEST VIRGINIA...
  SOUTHEASTERN MERCER COUNTY IN SOUTHEAST WEST VIRGINIA...

* UNTIL 515 PM EDT

* AT 447 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
  A STRONG THUNDERSTORM NEAR CERES...MOVING TO THE NORTHEAST AT 5
  MPH.

* VERY HEAVY RAIN IS FALLING...AND WILL CAUSE WATER TO POND ON
  ROADWAYS AND QUICKLY FILL ROADSIDE DITCHES AND SMALL STREAMS.
  EXPECT FREQUENT CLOUD TO GROUND LIGHTNING WITH THIS STORM.

* LOCATIONS IMPACTED INCLUDE...
  PRINCETON...
  AND CERES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

PROLONGED HEAVY RAINFALL MAY CAUSE WATER TO FLOW OVER THE ROADWAY. DO
NOT DRIVE YOUR VEHICLE WHERE THE ROAD HAS BECOME FLOODED.

&&

LAT...LON 3740 8108 3728 8099 3727 8101 3726 8099
      3725 8101 3722 8117 3733 8122
TIME...MOT...LOC 2047Z 247DEG 6KT 3730 8112

MBS