Alert archive / Virginia / Mesoscale Discussions in 2017

Mesoscale Discussion 874

May 27, 20174 states

The Storm Prediction Center issued this mesoscale discussion at May 27, 2017, 6:11 PM EDT for 4 states. It was in force for 64 min.

The area

The outline as issued.

The facts

Issued: May 27, 2017, 6:11 PM EDT (22:11 UTC)
Expired: May 27, 2017, 7:15 PM EDT
In force: 64 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 76 counties

Alexander County, NC, Alleghany County, NC, Ashe County, NC, Avery County, NC, Burke County, NC, Caldwell County, NC, Catawba County, NC, Davie County, NC, Forsyth County, NC, Iredell County, NC, Madison County, NC, McDowell County, NC, Mitchell County, NC, Rockingham County, NC, Stokes County, NC, Surry County, NC, Watauga County, NC, Wilkes County, NC, Yadkin County, NC, Yancey County, NC, Anderson County, TN, Blount County, TN, Campbell County, TN, Carter County, TN, Claiborne County, TN, Cocke County, TN, Grainger County, TN, Greene County, TN, Hamblen County, TN, Hancock County, TN, Hawkins County, TN, Jefferson County, TN, Johnson County, TN, Knox County, TN, Loudon County, TN, Morgan County, TN, Roane County, TN, Sevier County, TN, Sullivan County, TN, Unicoi County, TN, Union County, TN, Washington County, TN, Alleghany County, VA, Bedford County, VA, Bland County, VA, Botetourt County, VA, Carroll County, VA, City of Bristol, VA, City of Covington, VA, City of Danville, VA, City of Galax, VA, City of Martinsville, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, Craig County, VA, Floyd County, VA, Franklin County, VA, Giles County, VA, Grayson County, VA, Henry County, VA, Lee County, VA, Montgomery County, VA, Patrick County, VA, Pittsylvania County, VA, Pulaski County, VA, Roanoke County, VA, Russell County, VA, Scott County, VA, Smyth County, VA, Tazewell County, VA, Washington County, VA, Wythe County, VA, Mercer County, WV, Monroe County, WV, Summers County, WV

The radar

The Knoxville radar (KMRX), 122 km from the middle of the area, began a volume at 22:11 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 282May 27, 6:55 PM EDT

The nearest sounding before it

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 10.2 hours before the alert went out and 205 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: 24 J/kg
Mixed-layer CIN: -544 J/kg
Mixed-layer LCL: 1610 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 38 m²/s²
0-3 km storm-relative helicity: 140 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 27, 4:16 PM EDT	Mesoscale Discussion	SPC	Caswell, Granville, Halifax, Northampton, Person, Rockingham and 2 more	89 min
May 27, 4:43 PM EDT	Severe Thunderstorm Watch	SPC	Bertie, Camden, Chowan, Currituck, Edgecombe, Franklin and 11 more	5 hr
May 27, 6:55 PM EDT	Severe Thunderstorm Watch	SPC	Alexander, Alleghany, Ashe, Avery, Buncombe, Burke and 32 more	9 hr
May 27, 6:57 PM EDT	Mesoscale Discussion	SPC	Bertie, Camden, Chowan, Currituck, Edgecombe, Franklin and 13 more	93 min
May 27, 4:54 AM EDT	Mesoscale Discussion	SPC	Dyer, Lake, Lauderdale, Obion	2 hr
May 27, 5:19 AM EDT	Severe Thunderstorm Watch	SPC	Benton, Carroll, Chester, Crockett, Decatur, Dyer and 15 more	6 hr
May 27, 7:12 AM EDT	Mesoscale Discussion	SPC	Benton, Carroll, Chester, Crockett, Decatur, Dyer and 15 more	2 hr
May 27, 8:49 AM EDT	Mesoscale Discussion	SPC	Benton, Carroll, Chester, Crockett, Decatur, Dyer and 12 more	86 min
May 27, 10:13 AM EDT	Mesoscale Discussion	SPC	Anderson, Bedford, Benton, Bledsoe, Campbell, Cannon and 57 more	92 min
May 27, 1:50 PM EDT	Mesoscale Discussion	SPC	Anderson, Campbell, Claiborne, Clay, Fentress, Grainger and 9 more	85 min
May 27, 2:16 PM EDT	Mesoscale Discussion	SPC	Benton, Carroll, Crockett, Dyer, Gibson, Henry and 7 more	59 min
May 27, 2:36 PM EDT	Severe Thunderstorm Watch	SPC	Benton, Carroll, Cheatham, Clay, Davidson, Dickson and 21 more	7 hr
May 27, 4:50 PM EDT	Mesoscale Discussion	SPC	Benton, Carroll, Cheatham, Clay, Davidson, Dickson and 19 more	85 min
May 27, 6:13 PM EDT	Severe Thunderstorm Watch PDS	SPC	Bedford, Benton, Cannon, Carroll, Cheatham, Clay and 40 more	7 hr
May 27, 4:11 PM EDT	Severe Thunderstorm Watch	SPC	Buchanan, Dickenson	6 hr

Nearby

Mesoscale Discussions in Virginia, 2017 Mesoscale Discussions in Tennessee, 2017 Mesoscale Discussions in North Carolina, 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.