Alert archive / Virginia / Flash Flood Watches in 2018

Flash Flood Watch 11, NWS Blacksburg, VA

September 10, 20187 counties in Virginia; Alleghany County, Ashe County, Watauga County, North Carolina; Greenbrier County, Mercer County, Summers County, West Virginia

NWS Blacksburg, VA issued this flash flood watch at Sep 10, 2018, 1:25 PM EDT for 7 counties in Virginia; Alleghany County, Ashe County, Watauga County, North Carolina; Greenbrier County, Mercer County, Summers County, West Virginia. It was in force for 8 hr.

The area

The counties it named.

The facts

Issued: Sep 10, 2018, 1:25 PM EDT (17:25 UTC)
Expired: Sep 10, 2018, 9:27 PM EDT
In force: 8 hr
Issued by: NWS Blacksburg, VA
Flood severity: None

Counties Alleghany County, NC, Ashe County, NC, Watauga County, NC, Bland County, VA, Carroll County, VA, City of Galax, VA, Grayson County, VA, Smyth County, VA, Tazewell County, VA, Wythe County, VA, Greenbrier County, WV, Mercer County, WV, Summers County, WV

The radar

The Roanoke radar (KFCX), 78 km from the middle of the area, began a volume at 17:25 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 12:00Z, 5.4 hours before the alert went out and 147 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: 35 J/kg
Mixed-layer CIN: -97 J/kg
Mixed-layer LCL: 475 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 130 m²/s²
0-3 km storm-relative helicity: 129 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 Sep 10, 9:35 AM EDT, 3 hours 50 minutes earlier.

Area forecast discussion, Sep 10, 9:35 AM EDT, 3 hours 50 minutes before

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Hazardous weather outlook, Sep 10, 5:59 AM EDT, 7 hours 26 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
Sep 9, 8:27 PM EDT	Special Weather Statement	RNK	Tazewell	63 min
Sep 10, 1:15 AM EDT	Areal Flood Advisory	RNK	Carroll, Grayson, Patrick, City of Galax	4 hr
Sep 10, 1:56 AM EDT	Special Weather Statement	RNK	Carroll, Floyd, Patrick, City of Galax	64 min
Sep 10, 3:09 AM EDT	Special Weather Statement	RNK	Floyd, Franklin, Montgomery, Patrick	51 min
Sep 10, 5:49 PM EDT	Special Weather Statement	RNK	Grayson	56 min
Sep 10, 6:29 PM EDT	Flash Flood Warning	RNK	Grayson	3 hr
Sep 10, 6:46 PM EDT	Areal Flood Advisory	RNK	Bland, Tazewell	6 hr
Sep 10, 5:45 PM EDT	Special Weather Statement	RNK	Mercer	60 min
Sep 10, 7:27 PM EDT	Special Weather Statement	RNK	Summers	33 min

Nearby

Flash Flood Watches in Virginia, 2018 Flash Flood Watches in North Carolina, 2018 Flash Flood Watches in West Virginia, 2018 Every flash flood watch in 2018

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.