Alert archive / Virginia / Mesoscale Discussions in 2018

Mesoscale Discussion 490

May 22, 20184 counties in Maryland; 53 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at May 22, 2018, 1:52 PM EDT for 4 counties in Maryland; 53 counties in Virginia. It was in force for 113 min.

The area

The outline as issued.

The facts

Issued: May 22, 2018, 1:52 PM EDT (17:52 UTC)
Expired: May 22, 2018, 3:45 PM EDT
In force: 113 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

All 57 counties

Calvert County, MD, Charles 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, 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 Harrisonburg, VA, City of Hopewell, VA, City of Manassas, VA, City of Manassas Park, VA, City of Richmond, VA, City of Waynesboro, VA, Culpeper County, VA, Cumberland County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Goochland County, VA, Greene County, VA, Hanover County, VA, Henrico 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, 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, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Westmoreland County, VA

The radar

The Sterling radar (KLWX), 98 km from the middle of the area, began a volume at 17:55 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 116May 22, 2:30 PM EDT

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 5.9 hours before the alert went out and 97 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

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 22, 2:33 PM EDT	Severe Thunderstorm Watch	SPC	Anne Arundel, Calvert, Charles, Howard, Montgomery, Prince George's and 1 more	6 hr
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

Mesoscale Discussions in Virginia, 2018 Mesoscale Discussions in Maryland, 2018 Every mesoscale discussion 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.