Alert archive / Virginia / Mesoscale Discussions in 2021

Mesoscale Discussion 226

March 18, 202127 counties in North Carolina; 34 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Mar 18, 2021, 7:49 PM EDT for 27 counties in North Carolina; 34 counties in Virginia. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued: Mar 18, 2021, 7:49 PM EDT (23:49 UTC)
Expired: Mar 18, 2021, 8:45 PM EDT
In force: 56 min
Issued by: the Storm Prediction Center
Concerning: Tornado watch 42...43

All 61 counties

Alamance County, NC, Anson County, NC, Chatham County, NC, Cumberland County, NC, Durham County, NC, Edgecombe County, NC, Franklin County, NC, Gates County, NC, Granville County, NC, Halifax County, NC, Harnett County, NC, Hertford County, NC, Hoke County, NC, Johnston County, NC, Lee County, NC, Montgomery County, NC, Moore County, NC, Nash County, NC, Northampton County, NC, Orange County, NC, Person County, NC, Randolph County, NC, Richmond County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Wilson County, NC, Amelia County, VA, Brunswick County, VA, Charles City County, VA, Chesterfield County, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Emporia, VA, City of Franklin, VA, City of Hampton, VA, City of Hopewell, VA, City of Newport News, VA, City of Norfolk, VA, City of Petersburg, VA, City of Poquoson, VA, City of Portsmouth, VA, City of Richmond, VA, City of Suffolk, VA, City of Virginia Beach, VA, City of Williamsburg, VA, Dinwiddie County, VA, Gloucester County, VA, Greensville County, VA, Henrico County, VA, Isle of Wight County, VA, James City County, VA, Lunenburg County, VA, Mecklenburg County, VA, New Kent County, VA, Nottoway County, VA, Prince George County, VA, Southampton County, VA, Surry County, VA, Sussex County, VA, York County, VA

The radar

The Raleigh/Durham radar (KRAX), 74 km from the middle of the area, began a volume at 23:52 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 nearest sounding before it

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 11.8 hours before the alert went out and 169 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: 486 m above ground
0-6 km bulk shear: 67 kt
0-1 km storm-relative helicity: 470 m²/s²
0-3 km storm-relative helicity: 562 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
Mar 18, 10:34 AM EDT	Mesoscale Discussion	SPC	Cabarrus, Cleveland, Gaston, Lincoln, Mecklenburg, Rowan and 1 more	2 hr
Mar 18, 2:08 PM EDT	Tornado Watch	SPC	Cabarrus, Cleveland, Gaston, Lincoln, Mecklenburg, Union	4 hr
Mar 18, 3:10 PM EDT	Mesoscale Discussion	SPC	Cabarrus, Cleveland, Gaston, Lincoln, Mecklenburg, Rutherford and 2 more	3 hr
Mar 18, 4:45 PM EDT	Tornado Watch	SPC	Alamance, Anson, Chatham, Cumberland, Davidson, Durham and 20 more	4 hr
Mar 18, 5:09 PM EDT	Tornado Watch	SPC	Bertie, Camden, Chowan, Currituck, Gates, Hertford and 3 more	6 hr
Mar 18, 5:57 PM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Beaufort, Bertie, Cabarrus, Camden and 45 more	63 min
Mar 18, 2:25 PM EDT	Mesoscale Discussion	SPC	Bland, Buchanan, Dickenson, Russell, Tazewell, Washington and 2 more	3 hr

Nearby

Mesoscale Discussions in Virginia, 2021 Mesoscale Discussions in North Carolina, 2021 Every mesoscale discussion in 2021

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.