Alert archive / Virginia / Mesoscale Discussions in 2017

Mesoscale Discussion 624

May 1, 201736 counties in Virginia; 9 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at May 1, 2017, 2:29 PM EDT for 36 counties in Virginia; 9 counties in West Virginia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: May 1, 2017, 2:29 PM EDT (18:29 UTC)
Expired: May 1, 2017, 4:30 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 60%

All 45 counties

Alleghany County, VA, Amherst County, VA, Appomattox County, VA, Augusta County, VA, Bath County, VA, Bedford County, VA, Bland County, VA, Botetourt County, VA, Campbell County, VA, Carroll County, VA, City of Buena Vista, VA, City of Covington, VA, City of Harrisonburg, VA, City of Lexington, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, City of Staunton, VA, City of Waynesboro, VA, Craig County, VA, Floyd County, VA, Franklin County, VA, Giles County, VA, Henry County, VA, Highland County, VA, Montgomery County, VA, Nelson County, VA, Patrick County, VA, Pittsylvania County, VA, Pulaski County, VA, Roanoke County, VA, Rockbridge County, VA, Rockingham County, VA, Wythe County, VA, Greenbrier County, WV, Mercer County, WV, Monroe County, WV, Nicholas County, WV, Pendleton County, WV, Pocahontas County, WV, Randolph County, WV, Summers County, WV, Webster County, WV

The radar

The Roanoke radar (KFCX), 102 km from the middle of the area, began a volume at 18:30 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 186May 1, 5:55 PM EDT

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 6.5 hours before the alert went out and 91 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: 25 J/kg
Mixed-layer CIN: -10 J/kg
Mixed-layer LCL: 706 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 255 m²/s²
0-3 km storm-relative helicity: 277 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

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 1, 5:54 PM EDT	Severe Thunderstorm Watch	SPC	Albemarle, Amelia, Amherst, Appomattox, Arlington, Augusta and 61 more	5 hr
May 1, 11:59 AM EDT	Mesoscale Discussion	SPC	Barbour, Boone, Braxton, Brooke, Calhoun, Clay and 26 more	2 hr
May 1, 12:32 PM EDT	Tornado Watch	SPC	Barbour, Brooke, Doddridge, Hancock, Harrison, Marion and 12 more	4 hr
May 1, 4:36 PM EDT	Mesoscale Discussion	SPC	Grant, Mineral	84 min

Nearby

Mesoscale Discussions in Virginia, 2017 Mesoscale Discussions in West Virginia, 2017 Every mesoscale discussion 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.