Alert archive / Virginia / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 250, NWS Blacksburg, VA

August 20, 2009Bedford County, Franklin County, Roanoke County, Virginia

NWS Blacksburg, VA issued this severe thunderstorm warning at Aug 20, 2009, 2:27 PM EDT for Bedford County, Franklin County, Roanoke County, Virginia. It was in force for 63 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 20, 2009, 2:27 PM EDT (18:27 UTC)
Expired: Aug 20, 2009, 3:30 PM EDT
In force: 63 min
Issued by: NWS Blacksburg, VA
Area: Storm-based polygon

Counties Bedford County, VA, Franklin County, VA, Roanoke County, VA

The radar

The Roanoke radar (KFCX), 44 km from the middle of the area, began a volume at 18:27 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 6.5 hours before the alert went out and 28 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 144 J/kg
Mixed-layer CIN: -111 J/kg
Mixed-layer LCL: 756 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 32 m²/s²
0-3 km storm-relative helicity: 81 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Blacksburg, VA wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 20, 11:05 AM EDT, 3 hours 22 minutes earlier.

Area forecast discussion, Aug 20, 11:05 AM EDT, 3 hours 22 minutes before

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Hazardous weather outlook, Aug 20, 4:13 AM EDT, 10 hours 14 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
413 AM EDT THU AUG 20 2009

NCZ001>006-018>020-VAZ007-009>020-022>024-032>035-043>047-058-059-
WVZ042>045-210815-
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-
413 AM EDT THU AUG 20 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.

THERE IS A THREAT FOR VERY HEAVY RAIN FROM THUNDERSTORMS TODAY
AND ISOLATED FLASH FLOODING IS POSSIBLE.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

SHOWERS AND THUNDERSTORMS ARE EXPECTED FRIDAY. HEAVY RAINFALL AND
ISOLATED FLOODING REMAINS A THREAT FROM THE STORMS...AND AN
ISOLATED SEVERE THUNDERSTORM IS POSSIBLE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

In the hours before

Local storm report, Aug 20, 10:38 AM EDT, 3 hours 49 minutes before

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Special weather statement, Aug 20, 1:33 PM EDT, 54 minutes before

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Special weather statement, Aug 20, 1:35 PM EDT, 52 minutes before

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Special weather statement, Aug 20, 1:53 PM EDT, 34 minutes before

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Special weather statement, Aug 20, 2:22 PM EDT, 5 minutes before

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The office that day

Everything else NWS Blacksburg, VA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 20, 1:33 PM EDT	Special Weather Statement	RNK	Carroll, City of Galax	27 min
Aug 20, 1:53 PM EDT	Special Weather Statement	RNK	Rockbridge, City of Lexington	52 min
Aug 20, 2:22 PM EDT	Special Weather Statement	RNK	Bedford	68 min
Aug 20, 2:33 PM EDT	Special Weather Statement	RNK	Montgomery, City of Radford	57 min
Aug 20, 3:41 PM EDT	Severe Thunderstorm Warning	RNK	Patrick	41 min
Aug 20, 3:49 PM EDT	Special Weather Statement	RNK	City of Lynchburg	56 min
Aug 20, 3:52 PM EDT	Special Weather Statement	RNK	City of Roanoke, City of Salem	53 min
Aug 20, 4:33 PM EDT	Special Weather Statement	RNK	Carroll	57 min
Aug 20, 4:38 PM EDT	Special Weather Statement	RNK	Alleghany, Bath, Rockbridge, City of Covington, City of Lexington	52 min
Aug 20, 4:45 PM EDT	Special Weather Statement	RNK	Buckingham	60 min
Aug 20, 5:01 PM EDT	Special Weather Statement	RNK	Pulaski, Wythe	59 min
Aug 20, 5:20 PM EDT	Flash Flood Warning	RNK	Wythe	3 hr
Aug 20, 5:38 PM EDT	Special Weather Statement	RNK	Patrick	67 min
Aug 20, 6:23 PM EDT	Special Weather Statement	RNK	Botetourt, City of Roanoke, City of Salem	67 min
Aug 20, 6:27 PM EDT	Special Weather Statement	RNK	Amherst	63 min
Aug 20, 6:44 PM EDT	Special Weather Statement	RNK	Patrick	61 min
Aug 20, 7:11 PM EDT	Severe Thunderstorm Warning	RNK	Patrick	64 min
Aug 19, 8:06 PM EDT	Flash Flood Warning	RNK	Watauga, Wilkes	4 hr
Aug 19, 9:09 PM EDT	Special Weather Statement	RNK	Stokes, Surry, Yadkin	51 min
Aug 20, 1:35 PM EDT	Special Weather Statement	RNK	Caswell	40 min
Aug 20, 3:00 PM EDT	Special Weather Statement	RNK	Surry	60 min
Aug 20, 5:34 PM EDT	Flash Flood Warning	RNK	Ashe	6 hr

Nearby

Severe Thunderstorm Warnings in Virginia, 2009 Every severe thunderstorm warning in 2009

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.