Alert archive / Virginia / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 192, NWS Blacksburg, VA

July 17, 2009Charlotte County, Halifax County, Virginia

NWS Blacksburg, VA issued this severe thunderstorm warning at Jul 17, 2009, 12:27 PM EDT for Charlotte County, Halifax County, Virginia. It was in force for 39 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: Jul 17, 2009, 12:27 PM EDT (16:27 UTC)
Expired: Jul 17, 2009, 1:06 PM EDT
In force: 39 min
Issued by: NWS Blacksburg, VA
Area: Storm-based polygon

Counties Charlotte County, VA, Halifax County, VA

The radar

The Roanoke radar (KFCX), 132 km from the middle of the area, began a volume at 16:28 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 17, 10:29 AM EDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 4.5 hours before the alert went out and 71 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: 1643 J/kg
Mixed-layer CIN: -13 J/kg
Mixed-layer LCL: 578 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 74 m²/s²
0-3 km storm-relative helicity: 76 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 4.6

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 Jul 17, 12:00 PM EDT, 27 minutes earlier.

Area forecast discussion, Jul 17, 12:00 PM EDT, 27 minutes before

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Hazardous weather outlook, Jul 17, 12:02 PM EDT, 25 minutes before

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In the hours before

Local storm report, Jul 17, 11:32 AM EDT, 55 minutes before

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Local storm report, Jul 17, 11:50 AM EDT, 37 minutes before

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Local storm report, Jul 17, 11:54 AM EDT, 33 minutes before

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Local storm report, Jul 17, 11:57 AM EDT, 30 minutes before

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Local storm report, Jul 17, 12:10 PM EDT, 17 minutes before

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Local storm report, Jul 17, 12:15 PM EDT, 12 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
Jul 17, 7:31 AM EDT	Special Weather Statement	RNK	Wythe	59 min
Jul 17, 7:33 AM EDT	Severe Thunderstorm Warning	RNK	Carroll, Grayson, Pulaski, Wythe, City of Galax	57 min
Jul 17, 8:28 AM EDT	Severe Thunderstorm Warning	RNK	Carroll, Floyd, Montgomery, Pulaski, City of Radford	62 min
Jul 17, 9:42 AM EDT	Severe Thunderstorm Warning	RNK	Bedford, Botetourt, Floyd, Franklin, Montgomery, Roanoke and 2 more	63 min
Jul 17, 10:03 AM EDT	Severe Thunderstorm Warning	RNK	Bedford, Franklin, Pittsylvania	57 min
Jul 17, 10:34 AM EDT	Severe Thunderstorm Warning	RNK	Bedford, Campbell, Charlotte, Franklin, Halifax, Pittsylvania	56 min
Jul 17, 11:21 AM EDT	Tornado Warning	RNK	Appomattox, Campbell, Charlotte, Halifax, Pittsylvania	39 min
Jul 17, 11:30 AM EDT	Areal Flood Advisory	RNK	Appomattox, Campbell, Charlotte, Halifax, Pittsylvania	3 hr
Jul 17, 11:49 AM EDT	Severe Thunderstorm Warning	RNK	Halifax, Pittsylvania	56 min
Jul 17, 11:58 AM EDT	Severe Thunderstorm Warning	RNK	Appomattox, Campbell, Charlotte, Halifax	62 min
Jul 17, 2:39 PM EDT	Special Weather Statement	RNK	Bland, Tazewell	66 min
Jul 17, 4:01 PM EDT	Special Weather Statement	RNK	Pulaski, City of Radford	29 min
Jul 17, 4:15 PM EDT	Special Weather Statement	RNK	City of Roanoke	30 min
Jul 17, 4:33 PM EDT	Special Weather Statement	RNK	Floyd, Franklin	57 min
Jul 17, 4:44 PM EDT	Severe Thunderstorm Warning	RNK	Bedford, Campbell, Franklin, Pittsylvania	61 min
Jul 17, 5:45 PM EDT	Severe Thunderstorm Warning	RNK	Bedford, Campbell, Charlotte, Halifax, Pittsylvania	90 min
Jul 17, 6:09 AM EDT	Special Weather Statement	RNK	Mercer	36 min

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.