Alert archive / Virginia / Severe Thunderstorm Watches in 2018

Severe Thunderstorm Watch 116

May 22, 20187 counties in Maryland; 56 counties in Virginia

The Storm Prediction Center issued this severe thunderstorm watch at May 22, 2018, 2:33 PM EDT for 7 counties in Maryland; 56 counties in Virginia. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: May 22, 2018, 2:33 PM EDT (18:33 UTC)
Expired: May 22, 2018, 8:19 PM EDT
In force: 6 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 63 counties

Anne Arundel County, MD, Calvert County, MD, Charles County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Saint Mary's County, MD, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Arlington County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charles City County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Colonial Heights, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Richmond, VA, City of Williamsburg, VA, Clarke County, VA, Culpeper County, VA, Cumberland County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Gloucester County, VA, Goochland County, VA, Greene County, VA, Hanover County, VA, Henrico County, VA, James City County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Mathews County, VA, Middlesex County, VA, Nelson County, VA, New Kent County, VA, Northumberland County, VA, Orange County, VA, Page County, VA, Powhatan County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Westmoreland County, VA

The radar

The Sterling radar (KLWX), 113 km from the middle of the area, began a volume at 18:34 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: 2%
Ten or more severe wind reports: 60%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 20%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
May 22, 3:14 PM EDT	Severe Thunderstorm Warning	LWX	Albemarle, Greene, Madison, Orange, Rockingham, City of Charlottesville	46 min
May 22, 3:25 PM EDT	Severe Thunderstorm Warning	LWX	Frederick, Montgomery	50 min
May 22, 4:48 PM EDT	Severe Thunderstorm Warning	LWX	Fairfax, Prince William, City of Fairfax	42 min
May 22, 5:08 PM EDT	Severe Thunderstorm Warning	LWX	Charles, Prince George's	52 min
May 22, 5:24 PM EDT	Severe Thunderstorm Warning	LWX	Anne Arundel	16 min
May 22, 6:52 PM EDT	Severe Thunderstorm Warning	RNK	Bedford, Campbell, Franklin, Pittsylvania, City of Lynchburg	53 min
May 22, 6:58 PM EDT	Flash Flood Warning	AKQ	Chesterfield, Hanover, Henrico, City of Richmond	92 min
May 22, 7:51 PM EDT	Flash Flood Warning	RNK	Appomattox, Buckingham	6 hr
May 22, 7:54 PM EDT	Severe Thunderstorm Warning	RNK	Appomattox, Campbell, Halifax, Pittsylvania	51 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, 6.6 hours before the alert went out and 113 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: 744 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 60 m²/s²
0-3 km storm-relative helicity: 99 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
May 22, 1:52 PM EDT	Mesoscale Discussion	SPC	Calvert, Charles, Prince George's, Saint Mary's	113 min
May 22, 4:50 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Calvert, Charles, Montgomery, Prince George's, Saint Mary's	115 min
May 22, 7:24 PM EDT	Mesoscale Discussion	SPC	Calvert, Saint Mary's	96 min

Nearby

Severe Thunderstorm Watches in Virginia, 2018 Severe Thunderstorm Watches in Maryland, 2018 Every severe thunderstorm 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.