Alert archive / Virginia / Flash Flood Watches in 2009

Flash Flood Watch 9, NWS Blacksburg, VA

August 2, 200917 counties in Virginia; 7 counties in North Carolina; Mercer County, Monroe County, Summers County, West Virginia

NWS Blacksburg, VA issued this flash flood watch at Aug 2, 2009, 12:40 AM EDT for 17 counties in Virginia; 7 counties in North Carolina; Mercer County, Monroe County, Summers County, West Virginia. It was in force for 15 hr.

The area

The counties it named.

The facts

Issued: Aug 2, 2009, 12:40 AM EDT (04:40 UTC)
Expired: Aug 2, 2009, 4:00 PM EDT
In force: 15 hr
Issued by: NWS Blacksburg, VA
Flood severity: None

All 27 counties

Alleghany County, NC, Ashe County, NC, Stokes County, NC, Surry County, NC, Watauga County, NC, Wilkes County, NC, Yadkin County, NC, Alleghany County, VA, Bath County, VA, Bland County, VA, Carroll County, VA, City of Covington, VA, City of Galax, VA, City of Radford, VA, Craig County, VA, Floyd County, VA, Giles County, VA, Grayson County, VA, Montgomery County, VA, Patrick County, VA, Pulaski County, VA, Smyth County, VA, Tazewell County, VA, Wythe County, VA, Mercer County, WV, Monroe County, WV, Summers County, WV

The radar

The Roanoke radar (KFCX), 44 km from the middle of the area, began a volume at 04:42 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 00:00Z, 4.7 hours before the alert went out and 115 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: 1095 J/kg
Mixed-layer CIN: -8 J/kg
Mixed-layer LCL: 888 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 31 m²/s²
0-3 km storm-relative helicity: 67 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 1.3

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch 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 flash flood watch went out at Aug 1, 10:09 PM EDT, 2 hours 31 minutes earlier.

Area forecast discussion, Aug 1, 10:09 PM EDT, 2 hours 31 minutes before

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Hazardous weather outlook, Aug 1, 11:47 PM EDT, 53 minutes before

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In the hours before

Special weather statement, Aug 1, 8:10 PM EDT, 4 hours 30 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
810 PM EDT SAT AUG 1 2009

NCZ002-003-019-VAZ016-032-020100-
ALLEGHANY NC-CARROLL VA-PATRICK VA-SURRY NC-WILKES NC-
810 PM EDT SAT AUG 1 2009

...THUNDERSTORMS WITH VERY HEAVY RAIN WILL AFFECT PORTIONS OF
ALLEGHANY...CARROLL...PATRICK...SURRY AND WILKES COUNTIES...

AT 804 PM EDT...A LINE OF THUNDERSTORMS WITH MODERATE TO HEAVY RAIN
REMAINED NEARLY STATIONARY FROM THE FOOTHILLS OF WILKES COUNTY NORTH
CAROLINA TO ALONG THE SPINE OF THE BLUE RIDGE SOUTH AND EAST OF
HILLSVILLE VIRGINIA.

HEAVY RAIN WILL GRADUALLY DIMINISH AS THE EVENING PROGRESSES...BUT
RUNOFF WILL CAUSE WATER TO POND ON ROADS AND QUICKLY FILL ROADSIDE
DITCHES AND SMALL STREAMS.

PLEASE USE CAUTION AND AVOID DRIVING THROUGH WATER COVERED ROADS OR
IN AREAS WHERE WATER HAS PONDED IN LOW LYING AREAS.

LAT...LON 3611 8154 3657 8093 3656 8084 3661 8088
      3676 8068 3667 8035 3602 8135

EXPERIMENTAL

WERT

Local storm report, Aug 1, 8:45 PM EDT, 3 hours 55 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BLACKSBURG VA
845 PM EDT SAT AUG 01 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0715 PM     HAIL             1 NE GRETNA             36.96N 79.35W
08/01/2009  E0.75 INCH       PITTSYLVANIA       VA   PUBLIC

&&

TW

Special weather statement, Aug 1, 9:25 PM EDT, 3 hours 15 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
925 PM EDT SAT AUG 1 2009

NCZ019-020215-
WILKES NC-
925 PM EDT SAT AUG 1 2009

...STRONG THUNDERSTORMS WILL AFFECT WILKES COUNTY...

AT 919 PM EDT...A CLUSTER STRONG THUNDERSTORMS WAS LOCATED OVER THE
NORTHEAST HALF OF WILKES COUNTY...MOVING EAST AT 5 MPH.

WIND GUSTS TO 30 MPH ARE POSSIBLE WITH THESE STORMS. VERY HEAVY RAIN
WILL FALL FROM THESE STORMS...AND WILL CAUSE WATER TO POND ON ROADS
AND QUICKLY FILL ROADSIDE DITCHES AND SMALL STREAMS.

AREAS THAT WILL BE AFFECTED BY THESE STORMS INCLUDE...NORTH
WILKESBORO...MULBERRY...DOCKERY...AND TRAPHILL.

LAT...LON 3629 8123 3643 8108 3641 8103 3637 8102
      3637 8098 3630 8087 3619 8087 3611 8110

EXPERIMENTAL

Local storm report, Aug 1, 10:19 PM EDT, 2 hours 21 minutes before

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Special weather statement, Aug 1, 10:46 PM EDT, 1 hour 54 minutes before

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Local storm report, Aug 1, 11:21 PM EDT, 1 hour 19 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 1, 10:46 PM EDT	Special Weather Statement	RNK	Campbell	59 min
Aug 2, 8:19 AM EDT	Special Weather Statement	RNK	Alleghany, Bath, Bland, Carroll, Craig, Giles and 6 more	56 min
Aug 2, 9:03 AM EDT	Special Weather Statement	RNK	Alleghany, City of Covington	57 min
Aug 1, 8:10 PM EDT	Special Weather Statement	RNK	Wilkes	50 min
Aug 1, 9:25 PM EDT	Special Weather Statement	RNK	Wilkes	50 min
Aug 1, 10:07 PM EDT	Flash Flood Warning	RNK	Surry, Wilkes, Yadkin	4 hr

Nearby

Flash Flood Watches in Virginia, 2009 Flash Flood Watches in North Carolina, 2009 Flash Flood Watches in West Virginia, 2009 Every flash flood watch 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.