Alert archive / Virginia / Flood Watches in 2008

Flood Watch 4, NWS Blacksburg, VA

December 11, 200820 counties in Virginia; Mercer County, Monroe County, Summers County, West Virginia

NWS Blacksburg, VA issued this flood watch at Dec 11, 2008, 9:54 AM EST for 20 counties in Virginia; Mercer County, Monroe County, Summers County, West Virginia. It took effect at Dec 11, 2008, 10:00 AM EST. It was in force for 11 hr.

The area

The counties it named.

The facts

Issued: Dec 11, 2008, 9:54 AM EST (14:54 UTC)
In effect from: Dec 11, 2008, 10:00 AM EST
Expired: Dec 11, 2008, 8:52 PM EST
In force: 11 hr
Issued by: NWS Blacksburg, VA
Flood severity: None

All 23 counties

Alleghany County, VA, Amherst County, VA, Bath County, VA, Bland County, VA, Botetourt County, VA, City of Buena Vista, VA, City of Covington, VA, City of Lexington, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, Craig County, VA, Giles County, VA, Montgomery County, VA, Pulaski County, VA, Roanoke County, VA, Rockbridge 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 14:56 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, 2.9 hours before the alert went out and 77 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 536 m above ground
0-6 km bulk shear: 67 kt
0-1 km storm-relative helicity: 152 m²/s²
0-3 km storm-relative helicity: 82 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 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 flood watch went out at Dec 11, 7:28 AM EST, 2 hours 26 minutes earlier.

Area forecast discussion, Dec 11, 7:28 AM EST, 2 hours 26 minutes before

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Hazardous weather outlook, Dec 11, 4:54 AM EST, 5 hours 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
Dec 11, 10:26 AM EST	River Flood Warning	RNK	Halifax	53 hr
Dec 11, 2:25 PM EST	Flash Flood Warning	RNK	Campbell, Charlotte, Halifax, Pittsylvania	6 hr
Dec 11, 4:35 PM EST	Flash Flood Warning	RNK	Carroll, Patrick, City of Galax	5 hr

Nearby

Flood Watches in Virginia, 2008 Flood Watches in West Virginia, 2008 Every flood watch in 2008

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.