Severe Thunderstorm Warning 141, NWS Blacksburg, VA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
323 PM EDT THU OCT 20 2005

.SHORT TERM (TONIGHT THROUGH FRIDAY NIGHT)...

LOOKING AT TWO MAIN AREAS OF FOCUS FOR PRECIPITATION THROUGH
SATURDAY MORNING. THE FIRST IS WITH ANY CONVERGENCE ALONG THE
SURFACE FRONT AND THE EASTERLY UPSLOPE LOW LEVEL WINDS TO THE NORTH
OF THE FRONT. THIS OF COURSE WILL BE HIGHLY DEPENDANT ON THE
LOCATION OF THE BOUNDARY. THE MODELS STILL MOVE THE FRONT INTO THE
SOUTHERN COUNTY WARNING AREA BY FRIDAY MORNING.

THE SECOND MECHANISM FOR RAIN WILL BE THE CLOSED UPPER LOW COMING
OUT OF THE KANSAS. THE LOW IS FORECAST TO WEAKEN INTO AN OPEN WAVE
AS IT CROSSES THE OHIO VALLEY. AS THIS SHORT WAVE MOVES EAST...THE
ASSOCIATED PRECIPITATION WILL MOVE FROM THE MID MISSISSIPPI VALLEY
INTO THE MID ATLANTIC REGION. THE TIMING OF THE 12Z MODELS SHOWS THE
BEST FORCING AND LIFT FROM THIS FEATURE ON FRIDAY AFTERNOON AND
FRIDAY NIGHT.

LOOKING AT OBSERVATIONS BEHIND THE BACKDOOR FRONT LAST
NIGHT...TEMPERATURES AND DEW POINTS REMAIN RELATIVELY MUGGY IN THE
VICINITY OF THE FRONT. WITH BOUNDARY SLOWLY MOVING THROUGH THE
REGION TONIGHT...TEMPERATURES WILL BE SLOW TO FALL AND WILL REMAIN
RELATIVELY MUGGY IN OUR AREA.  THEREFORE...WILL KEEP OVERNIGHT
TEMPERATURES ABOVE MOS BY A FEW DEGREES. WARM AIR ADVECTION OVER
RUNNING COLD WEDGE WILL PRODUCE RAIN AND DRIZZLE INTO FRIDAY NIGHT.
THIS PRECIPITATION WILL KEEP DIURNAL TEMPERATURE RANGES LOW WITH
OVERNIGHT LOWS IN THE 50S AND DAYTIME HIGHS IN THE 60S.

&&

.MID TERM (SATURDAY AND SATURDAY NIGHT)...

SATURDAY AND SATURDAY NIGHT....
A STRONGER COLD FRONT WILL GENERATE A SURFACE WAVE IN THE OHIO
VALLEY SATURDAY MORNING. THIS WAVE WILL INDUCE PRESSURE FALLS TO THE
NORTH AND HELP BREAK WEDGE BY SATURDAY AFTERNOON. A STRONGER COLD
FRONT FROM THE WEST SWEEPS THROUGH THE AREA BY SATURDAY EVENING AND
OFF THE EAST COAST BY SUNRISE SUNDAY MORNING. MODELS IN BETTER
AGREEMENT TODAY WITH UPPER LEVEL SUPPORT AND FRONTAL TIMING. TIMING
OF THE FRONTAL PASSAGE A LITTLE QUICKER BUT MODELS SHOWING SW FLOW
ALOFT SATURDAY NIGHT. THEREFORE WILL HANG ONTO POPS THROUGH MIDNIGHT
THEN DECREASE AFTER THAT...ESPECIALLY IN THE EAST.

&&

.LONG TERM (SUNDAY THROUGH THURSDAY)...

MODELS SHOWING SOME CONSISTENCY IN THE LONG TERM. UPPER LOW SPINS IN
THE GREAT LAKES-OHIO VALLEY-NEW ENGLAND REGIONS THROUGH MID WEEK.
DURING THIS TIME...SEVERAL SHORT WAVES WILL CROSS OVER THE AREA.
THESE WAVES AND CONTINUING NW FLOW ALONG WITH ABUNDANT LOW LEVEL
MOISTURE WILL BRING SHOWERS...MAINLY TO THE MOUNTAIN AND PARTICULAR
WESTERN SLOPES DURING THIS TIME. EACH WAVE WILL BRING IN
RE-ENFORCING COLD AIR KEEPING TEMPERATURES BELOW NORMAL. EVEN THOUGH
1000-850 MB THICKNESSES STAY AT OR ABOVE 1300M...850 MB
TEMPERATURES FALL INTO THE NEGATIVES. IF VERIFIED...THESE COLD
TEMPERATURES WILL CHANGE RAIN SHOWERS OVER TO SNOW SHOWERS FOR
ELEVATIONS AT OR ABOVE 4000 FT. ALSO DURING THIS TIME...NW FLOW
WORKING THROUGH THE MOUNTAINS WILL BRING BREEZY AND GUSTY CONDITIONS
TO THE AREA.

&&

.AVIATION...

FRONT WILL PROGRESS SOUTH OVERNIGHT FORMING A WEDGE THAT WILL HOLD
UNTIL SATURDAY MORNING. MVFR TO IFR CEILINGS AND VISIBILITIES WILL
DEVELOP OVERNIGHT ALONG WITH LIGHT RAIN AND DRIZZLE...ESPECIALLY
ALONG AND EAST OF THE BLUE RIDGE WHERE THERE WILL BE AN EASTERLY
UPSLOPE COMPONENT TO THE LOW LEVEL WINDS NORTH OF THE BOUNDARY.
LITTLE IMPROVEMENT IS EXPECTED ON FRIDAY.

&&

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

AMS/RCS/AMS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
505 AM EDT THU OCT 20 2005

NCZ001>006-018>020-VAZ007-009>020-022>024-032>035-043>047-058-059-
WVZ042>045-210915-
ASHE-ALLEGHANY-SURRY-STOKES-ROCKINGHAM-CASWELL-WATAUGA-WILKES-
YADKIN-TAZEWELL-SMYTH-BLAND-GILES-WYTHE-PULASKI-MONTGOMERY-
GRAYSON-CARROLL-FLOYD-CRAIG-BATH-ROANOKE-BOTETOURT-ROCKBRIDGE-
PATRICK-FRANKLIN-BEDFORD-AMHERST-HENRY-PITTSYLVANIA-CAMPBELL-
APPOMATTOX-BUCKINGHAM-HALIFAX-CHARLOTTE-MERCER-SUMMERS-MONROE-
GREENBRIER-
505 AM EDT THU OCT 20 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF 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

AN ISOLATED THUNDERSTORM IS POSSIBLE THIS AFTERNOON AND EVENING...AS
A COLD FRONT DROP SOUTH ACROSS THE REGION. THE BEST CHANCE WILL BE
ACROSS SOUTHWEST VIRGINIA.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED.