Alert archive / Virginia / Severe Thunderstorm Watches in 2011

Severe Thunderstorm Watch 57

March 23, 20114 states

The Storm Prediction Center issued this severe thunderstorm watch at Mar 23, 2011, 4:13 PM EDT for 4 states. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Mar 23, 2011, 4:13 PM EDT (20:13 UTC)
Expired: Mar 23, 2011, 9:04 PM EDT
In force: 5 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 59 counties

Allegany County, MD, Carroll County, MD, Frederick County, MD, Howard County, MD, Montgomery County, MD, Washington County, MD, Adams County, PA, Bedford County, PA, Blair County, PA, Cambria County, PA, Cumberland County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Mifflin County, PA, Perry County, PA, Somerset County, PA, Albemarle County, VA, Arlington County, VA, Augusta County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Greene County, VA, Highland County, VA, Loudoun County, VA, Madison County, VA, Nelson County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Berkeley County, WV, Grant County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV, Pendleton County, WV

The radar

The Sterling radar (KLWX), 91 km from the middle of the area, began a volume at 20:13 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 10%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 20%
One or more gusts of 65 knots or more: 20%
Ten or more severe hail reports: 30%
One or more hailstones of 2 inches or more: 20%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

13 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Mar 23, 4:31 PM EDT	Severe Thunderstorm Warning	CTP	Bedford, Somerset	29 min
Mar 23, 5:09 PM EDT	Tornado Warning	CTP	Cambria, Somerset	36 min
Mar 23, 5:19 PM EDT	Severe Thunderstorm Warning	LWX	Augusta, Highland	26 min
Mar 23, 5:36 PM EDT	Severe Thunderstorm Warning	CTP	Cumberland, Huntingdon, Juniata, Mifflin, Perry	39 min
Mar 23, 5:39 PM EDT	Severe Thunderstorm Warning	LWX	Augusta, Rockingham	36 min
Mar 23, 5:44 PM EDT	Severe Thunderstorm Warning	CTP	Bedford, Cambria, Somerset	31 min
Mar 23, 6:04 PM EDT	Severe Thunderstorm Warning	CTP	Bedford, Blair, Cambria, Somerset	26 min
Mar 23, 6:12 PM EDT	Severe Thunderstorm Warning	LWX	Grant, Hardy, Pendleton	48 min
Mar 23, 6:29 PM EDT	Severe Thunderstorm Warning	LWX	Allegany	23 min
Mar 23, 6:44 PM EDT	Tornado Warning	LWX	Grant, Hardy	31 min
Mar 23, 6:55 PM EDT	Severe Thunderstorm Warning	LWX	Rockingham, Shenandoah	35 min
Mar 23, 7:10 PM EDT	Severe Thunderstorm Warning	LWX	Frederick, Shenandoah, Warren	50 min
Mar 23, 7:51 PM EDT	Severe Thunderstorm Warning	LWX	Culpeper, Fauquier, Greene, Madison, Orange, Page and 4 more	39 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 8.2 hours before the alert went out and 98 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: 0 m above ground
0-6 km bulk shear: 67 kt
0-1 km storm-relative helicity: 304 m²/s²
0-3 km storm-relative helicity: 428 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 23, 1:13 PM EDT	Tornado Watch	SPC	Garrett	7 hr
Mar 23, 3:54 PM EDT	Mesoscale Discussion	SPC	Allegany, Garrett, Washington	96 min
Mar 23, 3:32 AM EDT	Mesoscale Discussion	SPC	Bradford, Carbon, Columbia, Lackawanna, Lehigh, Luzerne and 11 more	4 hr
Mar 23, 12:02 PM EDT	Mesoscale Discussion	SPC	Buchanan, Dickenson	88 min
Mar 23, 3:38 PM EDT	Mesoscale Discussion	SPC	Bland, Carroll, Giles, Grayson, Pulaski, Smyth and 6 more	37 min
Mar 23, 3:45 PM EDT	Tornado Watch	SPC	Alleghany, Amherst, Appomattox, Bath, Bedford, Bland and 38 more	6 hr
Mar 23, 4:48 PM EDT	Mesoscale Discussion	SPC	Amelia, Amherst, Appomattox, Bedford, Brunswick, Buckingham and 21 more	57 min
Mar 23, 6:04 PM EDT	Severe Thunderstorm Watch	SPC	Amelia, Brunswick, Caroline, Charles City, Chesterfield, Cumberland and 37 more	7 hr
Mar 23, 7:10 PM EDT	Mesoscale Discussion	SPC	Amelia, Amherst, Appomattox, Bedford, Brunswick, Buckingham and 21 more	65 min

Nearby

Severe Thunderstorm Watches in Virginia, 2011 Severe Thunderstorm Watches in Pennsylvania, 2011 Severe Thunderstorm Watches in West Virginia, 2011 Every severe thunderstorm watch in 2011

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.