Alert archive / Virginia / Mesoscale Discussions in 2017

Mesoscale Discussion 869

May 27, 20178 counties in North Carolina; 57 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at May 27, 2017, 4:16 PM EDT for 8 counties in North Carolina; 57 counties in Virginia. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued: May 27, 2017, 4:16 PM EDT (20:16 UTC)
Expired: May 27, 2017, 5:45 PM EDT
In force: 89 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 65 counties

Caswell County, NC, Granville County, NC, Halifax County, NC, Northampton County, NC, Person County, NC, Rockingham County, NC, Vance County, NC, Warren County, NC, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Augusta County, VA, Bedford County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Hopewell, VA, City of Lexington, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Petersburg, VA, City of Richmond, VA, City of Staunton, VA, City of Waynesboro, VA, Cumberland County, VA, Dinwiddie County, VA, Fluvanna County, VA, Franklin County, VA, Goochland County, VA, Greene County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, King William County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mecklenburg County, VA, Nelson County, VA, Nottoway County, VA, Orange County, VA, Page County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Rockbridge County, VA, Rockingham County, VA, Southampton County, VA, Spotsylvania County, VA, Sussex County, VA

The radar

The Roanoke radar (KFCX), 140 km from the middle of the area, began a volume at 20:16 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 278May 27, 4:45 PM EDT

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 8.3 hours before the alert went out and 72 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: 32 J/kg
Mixed-layer CIN: -429 J/kg
Mixed-layer LCL: 989 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 165 m²/s²
0-3 km storm-relative helicity: 231 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, 4:43 PM EDT	Severe Thunderstorm Watch	SPC	Bertie, Camden, Chowan, Currituck, Edgecombe, Franklin and 11 more	5 hr
May 27, 6:11 PM EDT	Mesoscale Discussion	SPC	Alexander, Alleghany, Ashe, Avery, Burke, Caldwell and 14 more	64 min
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, 1:50 PM EDT	Mesoscale Discussion	SPC	Dickenson, Lee, Wise, City of Norton	85 min
May 27, 4:11 PM EDT	Severe Thunderstorm Watch	SPC	Buchanan, Dickenson	6 hr

Nearby

Mesoscale Discussions in Virginia, 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.