Alert archive / Virginia / Flash Flood Watches in 2020

Flash Flood Watch 10, NWS Blacksburg, VA

August 13, 202032 counties in Virginia; 5 counties in North Carolina; Mercer County, West Virginia

NWS Blacksburg, VA issued this flash flood watch at Aug 13, 2020, 2:50 AM EDT for 32 counties in Virginia; 5 counties in North Carolina; Mercer County, West Virginia. It took effect at Aug 13, 2020, 12:00 PM EDT. It was in force for 12 hr.

The area

The counties it named.

The facts

Issued: Aug 13, 2020, 2:50 AM EDT (06:50 UTC)
In effect from: Aug 13, 2020, 12:00 PM EDT
Expired: Aug 14, 2020, 12:00 AM EDT
In force: 12 hr
Issued by: NWS Blacksburg, VA
Flood severity: None

All 38 counties

Alleghany County, NC, Ashe County, NC, Surry County, NC, Watauga County, NC, Wilkes County, NC, Alleghany County, VA, Amherst County, VA, Appomattox County, VA, Bath County, VA, Bedford County, VA, Bland County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, Carroll County, VA, Charlotte County, VA, City of Buena Vista, VA, City of Covington, VA, City of Galax, VA, City of Lexington, VA, City of Lynchburg, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, Craig County, VA, Floyd County, VA, Franklin County, VA, Giles County, VA, Grayson County, VA, Montgomery County, VA, Patrick County, VA, Pulaski County, VA, Roanoke County, VA, Rockbridge County, VA, Smyth County, VA, Tazewell County, VA, Wythe County, VA, Mercer County, WV

The radar

The Roanoke radar (KFCX), 15 km from the middle of the area, began a volume at 06:51 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

Greensboro/Hi Pt, NC (KGSO), launched 00:00Z, 6.8 hours before the alert went out and 123 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: 1248 J/kg
Mixed-layer CIN: -15 J/kg
Mixed-layer LCL: 1125 m above ground
0-6 km bulk shear: 11 kt
0-1 km storm-relative helicity: 21 m²/s²
0-3 km storm-relative helicity: 31 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 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 12, 10:03 PM EDT, 4 hours 47 minutes earlier.

Area forecast discussion, Aug 12, 10:03 PM EDT, 4 hours 47 minutes before

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Hazardous weather outlook, Aug 12, 10:59 PM EDT, 3 hours 51 minutes before

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In the hours before

Local storm report, Aug 12, 9:49 PM EDT, 5 hours 1 minute before

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Local storm report, Aug 12, 9:57 PM EDT, 4 hours 53 minutes before

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Local storm report, Aug 12, 10:03 PM EDT, 4 hours 47 minutes before

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Local storm report, Aug 12, 10:07 PM EDT, 4 hours 43 minutes before

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Local storm report, Aug 12, 10:08 PM EDT, 4 hours 42 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 13, 12:24 AM EDT	Areal Flood Advisory	RNK	Franklin, Henry, Patrick	2 hr
Aug 13, 2:45 AM EDT	Areal Flood Advisory	RNK	Campbell	3 hr
Aug 13, 7:10 AM EDT	Special Weather Statement	RNK	Appomattox	35 min
Aug 13, 7:32 AM EDT	Areal Flood Advisory	RNK	Appomattox	118 min
Aug 13, 2:59 PM EDT	Special Weather Statement	RNK	Grayson	31 min
Aug 13, 3:13 PM EDT	Areal Flood Advisory	RNK	Bland, Wythe	3 hr
Aug 13, 3:17 PM EDT	Areal Flood Advisory	RNK	Smyth	104 min
Aug 13, 3:34 PM EDT	Special Weather Statement	RNK	Bland, Wythe	41 min
Aug 13, 5:23 PM EDT	Flash Flood Warning	RNK	Alleghany, Botetourt, City of Covington	4 hr
Aug 13, 2:39 PM EDT	Areal Flood Advisory	RNK	Surry	2 hr
Aug 13, 2:48 PM EDT	Special Weather Statement	RNK	Surry	27 min
Aug 13, 2:51 PM EDT	Areal Flood Advisory	RNK	Ashe	3 hr
Aug 13, 3:45 PM EDT	Areal Flood Advisory	RNK	Wilkes, Yadkin	4 hr
Aug 13, 4:07 PM EDT	Flash Flood Warning	RNK	Surry, Wilkes, Yadkin	5 hr
Aug 13, 4:20 PM EDT	Flash Flood Warning	RNK	Ashe, Watauga, Wilkes	3 hr
Aug 13, 4:30 PM EDT	Areal Flood Advisory	RNK	Yadkin	3 hr
Aug 13, 7:09 PM EDT	Areal Flood Advisory	RNK	Greenbrier	111 min

Nearby

Flash Flood Watches in Virginia, 2020 Flash Flood Watches in North Carolina, 2020 Flash Flood Watches in West Virginia, 2020 Every flash flood watch in 2020

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.