Alert archive / Virginia / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 259, NWS Baltimore/Washington

September 5, 20174 counties in Virginia; Jefferson County, West Virginia

NWS Baltimore/Washington issued this severe thunderstorm warning at Sep 5, 2017, 4:46 PM EDT for 4 counties in Virginia; Jefferson County, West Virginia. It was in force for 44 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: Sep 5, 2017, 4:46 PM EDT (20:46 UTC)
Expired: Sep 5, 2017, 5:30 PM EDT
In force: 44 min
Issued by: NWS Baltimore/Washington
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Clarke County, VA, Fauquier County, VA, Loudoun County, VA, Warren County, VA, Jefferson County, WV

The radar

The Sterling radar (KLWX), 36 km from the middle of the area, began a volume at 20:45 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
Sep 5, 3:26 PM EDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 8.8 hours before the alert went out and 44 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: 4 J/kg
Mixed-layer CIN: -324 J/kg
Mixed-layer LCL: 1529 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 8 m²/s²
0-3 km storm-relative helicity: 79 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 severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Baltimore/Washington wrote its last area forecast discussion before this severe thunderstorm warning went out at Sep 5, 3:48 PM EDT, 58 minutes earlier.

Area forecast discussion, Sep 5, 3:48 PM EDT, 58 minutes before

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Hazardous weather outlook, Sep 5, 3:25 PM EDT, 1 hour 21 minutes before

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In the hours before

Local storm report, Sep 5, 4:18 PM EDT, 28 minutes before

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Local storm report, Sep 5, 4:21 PM EDT, 25 minutes before

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Local storm report, Sep 5, 4:37 PM EDT, 9 minutes before

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Local storm report, Sep 5, 4:40 PM EDT, 6 minutes before

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Local storm report, Sep 5, 4:41 PM EDT, 5 minutes before

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Local storm report, Sep 5, 4:42 PM EDT, 4 minutes before

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The office that day

Everything else NWS Baltimore/Washington issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 5, 2:43 PM EDT	Severe Thunderstorm Warning	LWX	Frederick	47 min
Sep 5, 2:49 PM EDT	Severe Thunderstorm Warning	LWX	Frederick, City of Winchester	41 min
Sep 5, 3:06 PM EDT	Tornado Warning	LWX	Frederick	24 min
Sep 5, 3:31 PM EDT	Severe Thunderstorm Warning	LWX	Clarke, Frederick, City of Winchester	44 min
Sep 5, 3:36 PM EDT	Severe Thunderstorm Warning	LWX	Albemarle, Augusta, Nelson, City of Charlottesville, City of Staunton, City of Waynesboro	39 min
Sep 5, 3:51 PM EDT	Severe Thunderstorm Warning	LWX	Loudoun	39 min
Sep 5, 4:12 PM EDT	Severe Thunderstorm Warning	LWX	Albemarle, Culpeper, Greene, Madison, Nelson, Orange and 1 more	48 min
Sep 5, 4:16 PM EDT	Severe Thunderstorm Warning	LWX	Clarke, Loudoun	29 min
Sep 5, 4:54 PM EDT	Special Marine Warning	LWX		96 min
Sep 5, 5:24 PM EDT	Special Marine Warning	LWX		96 min
Sep 5, 5:34 PM EDT	Severe Thunderstorm Warning	LWX	Clarke, Fauquier, Loudoun, Warren	26 min
Sep 5, 6:03 PM EDT	Special Marine Warning	LWX		57 min
Sep 5, 7:07 PM EDT	Special Marine Warning	LWX		23 min
Sep 4, 8:07 PM EDT	Coastal Flood Advisory	LWX	Anne Arundel	9 hr
Sep 5, 2:38 PM EDT	Severe Thunderstorm Warning	LWX	Allegany, Washington	22 min
Sep 5, 3:20 PM EDT	Severe Thunderstorm Warning	LWX	Frederick, Washington	40 min
Sep 5, 2:27 PM EDT	Severe Thunderstorm Warning	LWX	Hampshire	33 min

Nearby

Severe Thunderstorm Warnings in Virginia, 2017 Severe Thunderstorm Warnings in West Virginia, 2017 Every severe thunderstorm warning in 2017

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.