Special Weather Statement, NWS Blacksburg, VA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1139 PM EDT TUE OCT 7 2014

.SYNOPSIS...
UPPER DISTURBANCE MOVING ACROSS THE CENTRAL APPLACHIANS WILL KEEP
THE SHOWERS AROUND THROUGH EARLY MORNING. THE TROUGH OF LOW
PRESSURE IS EXPECTED TO LIFT NORTHEAST AND AWAY FROM THE AREA
WEDNESDAY...REPLACED BY HIGH PRESSURE THAT WILL BRING A RETURN TO
DRY AND MILD WEATHER FOR WEDNESDAY AND THURSDAY. BY FRIDAY
MORNING...THE HIGH WILL BE OFFSHORE AND LOW PRESSURE WILL BE
APPROACHING FROM THE TENNESSEE VALLEY.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 1130 PM EDT TUESDAY...

EVENING STAYING ACTIVE AS CONVECTION WITH HIGH WIND SHEAR...LOW
LVL JET CONTINUES TO BE AN ISSUE OVER ERN KY INTO SRN WV.
HRRR/LOCAL WRF SHOW THIS BROKEN LINE OF CONVECTION SHIFTING SWD
OVERNIGHT...AND MOST OF THE FORECAST AREA SHOULD BE DRY BY 8 AM.

MADE ADJUSTMENTS TO POPS TO ACCOUNT FOR SWD SHIFT IN
SHOWERS/ISOLATED TSRA INTO PREDAWN...BUT EXPECT WEAKENING THROUGH
THE NIGHT AS INSTABILITY IS ABOUT NIL. STORMS HAVE BEEN FEEDING
OFF LOW LVL BOUNDARY AND SHEAR. KEPT GUSTY WINDS IN THE FORECAST
OVER THE MTNS THROUGH ABOUT 3AM.

REMOVED/LOWERED POPS CONSIDERABLY AFTER 12Z WED. NO OTHER MAJOR
CHANGES TO THE PREVIOUS FORECAST ELEMENTS.

PREVIOUS VALID DISCUSSION...
BROAD UPPER LEVEL TROUGH WILL REMAIN OVER THE EASTERN U.S. WITH AXIS
EXTENDING FROM THE GREAT LAKES INTO THE TENNESSEE VALLEY.
EMBEDDED SHORTWAVES WILL ROTATE AROUND THE BASE OF THE UPPER
TROUGH THIS AFTERNOON INTO TONIGHT. THESE WILL CREATE ENOUGH
DYNAMIC LIFT TO COMBINE WITH THE LOW LEVEL MOISTURE CONVERGENCE TO
REGENERATE DEEPER CONVECTION.

NUMEROUS SHOWERS AND THUNDERSTORMS WILL CONTINUE UNTIL THE TROF
LIFTS NORTHEAST ON WEDNESDAY. SHOWERS AND THUNDERSTORMS THAT
DEVELOP IN SHORT LINE SEGMENTS WILL BE CAPABLE OF PRODUCING GUSTY
WINDS.

NOT CONCERNED OVER ANY FLOODING AT THIS TIME...UNLESS THE SHOWERS
AND THUNDERSTORMS TRAIN OVER THE SAME AREA IT WILL BE DIFFICULT TO
FOCUS THE HEAVY RAINFALL FOR ANY LENGTH OF TIME DUE TO THE FAST
STORM MOVEMENT...MEAN CLOUD LAYER WINDS OF 45 KTS. IN THIS HIGHLY
SHEARED ENVIRONMENT FOCUS SHOULD BE ON THE WIND AND NOT THE RAIN.
KEPT THE HIGHEST POPS IN THE WEST...THEN TAPER OFF AFTER 06Z GOING
INTO WEDNESDAY MORNING. PLAYED LOW TEMPERATURES TONIGHT CLOSE TO
THE ADJMAVBC WITH READINGS FROM THE UPPER 40S IN THE MOUNTAINS TO
AROUND 60 DEGREES IN THE PIEDMONT.

A LOW PRESSURE CENTER OVER EASTERN CANADA WILL DRAG A COLD FRONT
SOUTHWARD ACROSS OUR AREA WEDNESDAY MORNING. WINDS WILL GRADUALLY
SHIFT FROM SOUTHWESTERLY TO WESTERLY BY WEDNESDAY AFTERNOON AS HIGH
PRESSURE BUILDS IN. THE DOWNSLOPE FLOW WILL BRING AN END TO LEFTOVER
SHOWERS AND DIMINISH CLOUD COVER HEADING INTO THE AFTERNOON. THE
COMBINATION OF A RETREATING UPPER LEVEL TROUGHING AND SUNSHINE WILL
WARM AFTERNOON TEMPERATURES INTO THE MID 60S IN THE MOUNTAINS TO THE
LOWER 80S IN THE PIEDMONT.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 340 PM EDT TUESDAY...

SURFACE HIGH PRESSURE WILL BE CENTERED OVER THE FORECAST AREA
THURSDAY MORNING. WILL BE STAYING CLOSER TO THE COOLER MAV NUMBERS
FOR LOWS WEDNESDAY NIGHT.

BY FRIDAY MORNING THE HIGH WILL BE OFFSHORE AND LOW PRESSURE WILL BE
APPROACHING FROM THE TENNESSEE VALLEY. DEEP MOISTURE WILL RETURN TO
THE REGION BY THURSDAY NIGHT WITH A STATIONARY FRONT THAT WILL
EXTEND FROM WEST VIRGINIA INTO THE TENNESSEE VALLEY THURSDAY AND
FRIDAY.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 325 PM EDT TUESDAY...

LONG WAVE 500 TROF DIGS OVER THE CENTRAL UNITED STATES SUNDAY AND
MONDAY. ECMWF WAS MUCH MORE AMPLIFIED WITH THIS TROF THAN OTHER
SOLUTIONS...CLOSING OFF A LOW IN THE PLAINS MONDAY NIGHT. WILL BE
LEANING TOWARD MORE AMPLIFIED SOLUTION...THOUGH WITH LOWER
CONFIDENCE FOR MONDAY AND TUESDAY.

AT THE SURFACE...THE BOUNDARY SLOWLY SINKS SOUTH SATURDAY. TROFFING
REMAINS OVER THE TENNESSEE VALLEY SUNDAY AND MONDAY WITH A BUILDING
WEDGE OVER THE FORECAST AREA AS HIGH PRESSURE MOVES FROM THE GREAT
LAKES ACROSS NEW ENGLAND. BETTER VORTICITY ADVECTION AND UPPER
SUPPORT ARRIVE ON SATURDAY NIGHT. WILL KEEP HIGHEST PROBABILITY OF
PRECIPITATION FROM FRIDAY NIGHT INTO SATURDAY NIGHT. SURFACE HIGH
MOVES OFFSHORE BY TUESDAY AND DEEPER LOW PRESSURE WILL DEVELOP IN
THE MISSISSIPPI VALLEY.

850 MB TEMPERATURES WIND UP WARMER ON SUNDAY AND MONDAY BUT THAT MAY
NOT MAKE MUCH DIFFERENCE SINCE THE FORECAST AREA WILL BE WEDGED IN
AT THE SURFACE AND CLOUDY. WILL STAY AOB GUIDANCE FOR MAXIMUM
TEMPERATURES SUNDAY AND MONDAY. AS LONG AS WEDGE IS GONE ON
TUESDAY...TEMPERATURES HAVE THE POTENTIAL TO BE ABOVE NORMAL.

&&

.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
AS OF 738 PM EDT TUESDAY...

CONVECTION MOVING ACROSS SE WV THIS EVENING WILL IMPACT THE
BCB/ROA AREA AT TAF START TIME AND EVENTUALLY SKIRT BY LYH
BETWEEN 01-02Z. TSRA IS LIMITED SO ONLY HAVE IT IN AS VCTS AT BCB.

WITH THE SHOWERS EXPECT TORRENTIAL RAIN AT TIMES WHICH COULD BRING
VSBYS DOWN SOME WHILE KEEPING CIGS ABOVE MVFR. WITH LIGHTER
SHOWERS EXPECT CIGS TO DROP BACK DOWN. FOLLOWED THE LATEST HRRR
WHICH HAS THIS FIRST AREA MOVING OUT OF SE WV AND BCB BY 01Z...AND
ROANOKE AND LYH BY 02Z.

THERE IS SOME STRONG LOW LVL WINDS...AND AS SUCH FORECAST
SOUNDINGS SUGGEST LOW LVL WIND SHEAR. HOWEVER...FOR MOST AREAS
WINDS WILL BE MIXED ENOUGH PLUS WITH SHOWERS IN THE AREA IT WILL
BE MORE CONVECTIVE THAN NON. BUT DID ADD LLWS TO LYH/DAN
OVERNIGHT...AS NOT EXPECTING CONVECTION TO MAKE IT THIS FAR EAST
AFTER 05Z.

ONCE THIS UPPER SHORTWAVE MOVES EAST AFTER MIDNIGHT DRYING ALOFT
TAKES PLACE WITH WINDS TURNING MORE WESTERLY. ISSUE BECOMES FOG
AND/OR LOWER CIGS. THINK FOG WILL BE LIMITED AS WINDS STAY IN THE
4-8KT RANGE INCREASING IN THE MTNS. LWB THOUGH COULD CLEAR OUT
FASTER TOWARD DAWN WHICH MAY BRING ABOUT DENSE FOG...SO KEPT THAT
IN FROM PREVIOUS FORECAST. MOST TERMINALS WILL BE MVFR TO VFR.

THINGS CLEAR OUT FOR MOST OF WEDNESDAY WHILE WEST WINDS BECOME
GUSTY.

EXTENDED AVIATION DISCUSSION...

VFR CONDITIONS WILL PREVAIL INTO THURSDAY BEFORE ANOTHER WEATHER
DISTURBANCE IMPINGES ON THE AREA FROM THE WEST LATER THURSDAY
NIGHT OR ON FRIDAY. SUB VFR LIKELY TOWARD SAT-SUN AS THE FRONT
MOVES SOUTH AND SFC HIGH MOVING EAST FROM THE GREAT LAKES SETTING
UP A WEDGE SCENARIO...WITH RAIN EXPECTED AS WELL.

&&

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

&&

SYNOPSIS...KK/PM
NEAR TERM...KK/WP
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...KK/PM/WP

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
619 PM EDT TUE OCT 7 2014

VAZ007-009>011-018>020-WVZ042>044-507-508-082230-
TAZEWELL-SMYTH-BLAND-GILES-CRAIG-ALLEGHANY VA-BATH-MERCER-SUMMERS-
MONROE-EASTERN GREENBRIER-WESTERN GREENBRIER-
619 PM EDT TUE OCT 7 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWEST VIRGINIA...WEST
CENTRAL VIRGINIA...SOUTHEAST WEST VIRGINIA AND WV.

.DAY ONE...TONIGHT.

THERE IS A SMALL THREAT FOR STRONG THUNDERSTORMS THIS
EVENING...WITH THE MAIN THREAT BEING STRONG WIND GUSTS. CANNOT
RULE OUT A FEW GUSTS OVER 50 MPH WITH ISOLATED WIND DAMAGE.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

NCZ001>006-018>020-VAZ012>017-022>024-032>035-043>047-058-059-082230-
ASHE-ALLEGHANY NC-SURRY-STOKES-ROCKINGHAM-CASWELL-WATAUGA-WILKES-
YADKIN-WYTHE-PULASKI-MONTGOMERY-GRAYSON-CARROLL-FLOYD-ROANOKE-
BOTETOURT-ROCKBRIDGE-PATRICK-FRANKLIN-BEDFORD-AMHERST-HENRY-
PITTSYLVANIA-CAMPBELL-APPOMATTOX-BUCKINGHAM-HALIFAX-CHARLOTTE-
619 PM EDT TUE OCT 7 2014

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...TONIGHT.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

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
1219 AM EDT WED OCT 8 2014

VAZ022-023-034-080500-
BOTETOURT VA-BEDFORD VA-ROANOKE VA-
1219 AM EDT WED OCT 8 2014

THE NATIONAL WEATHER SERVICE IN BLACKSBURG HAS ISSUED A

* SPECIAL WEATHER STATEMENT FOR...
  SOUTHWESTERN BOTETOURT COUNTY IN WEST CENTRAL VIRGINIA...
  WEST CENTRAL BEDFORD COUNTY IN SOUTH CENTRAL VIRGINIA...
  NORTHEASTERN ROANOKE COUNTY IN WEST CENTRAL VIRGINIA...

* UNTIL 100 AM EDT

* AT 1219 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS
  TRACKING A STRONG THUNDERSTORM NEAR DALEVILLE...MOVING TO THE EAST
  AT 35 MPH.

* WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM.

* LOCATIONS IMPACTED INCLUDE...
  MONTVALE...
  TROUTVILLE...
  HOLLINS...
  THAXTON...
  AND CHAMBLISSBURG.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS STORM MAY INTENSIFY...SO MONITOR LOCAL RADIO AND TELEVISION FOR
ADDITIONAL INFORMATION...AND POSSIBLE WARNINGS...FROM THE NATIONAL
WEATHER SERVICE.

&&

LAT...LON 3741 7956 3723 7968 3738 8006 3751 8001
TIME...MOT...LOC 0417Z 288DEG 31KT 3740 7995

16

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