Alert archive / Virginia / Mesoscale Discussions in 2009

Mesoscale Discussion 738

May 6, 2009Dorchester County, Saint Mary's County, Somerset County, Maryland; 14 counties in North Carolina; 60 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at May 6, 2009, 10:50 PM EDT for Dorchester County, Saint Mary's County, Somerset County, Maryland; 14 counties in North Carolina; 60 counties in Virginia. It was in force for 55 min.

The area

The outline as issued.

The facts

Issued: May 6, 2009, 10:50 PM EDT (02:50 UTC)
Expired: May 6, 2009, 11:45 PM EDT
In force: 55 min
Issued by: the Storm Prediction Center

All 77 counties

Dorchester County, MD, Saint Mary's County, MD, Somerset County, MD, Alamance County, NC, Caswell County, NC, Durham County, NC, Franklin County, NC, Granville County, NC, Halifax County, NC, Hertford County, NC, Nash County, NC, Northampton County, NC, Orange County, NC, Person County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Accomack County, VA, Amelia County, VA, Appomattox 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 Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Franklin, VA, City of Hampton, VA, City of Hopewell, VA, City of Lynchburg, 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 Williamsburg, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fluvanna County, VA, Gloucester County, VA, Goochland County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Isle of Wight County, VA, James City County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Louisa County, VA, Lunenburg County, VA, Mathews County, VA, Mecklenburg County, VA, Middlesex County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Nottoway County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Richmond County, VA, Southampton County, VA, Surry County, VA, Sussex County, VA, Westmoreland County, VA, York County, VA

The radar

The Norfolk radar (KAKQ), 63 km from the middle of the area, began a volume at 02:52 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

Roanoke, VA (KRNK), launched 00:00Z, 2.8 hours before the alert went out and 160 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: 200 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 568 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 513 m²/s²
0-3 km storm-relative helicity: 631 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 3.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 6, 8:26 PM EDT	Tornado Watch	SPC	Calvert, Dorchester, Saint Mary's, Somerset, Wicomico, Worcester	8 hr
May 7, 12:10 AM EDT	Mesoscale Discussion	SPC	Anne Arundel, Calvert, Caroline, Cecil, Charles, Dorchester and 6 more	95 min
May 6, 11:44 PM EDT	Mesoscale Discussion	SPC	Buncombe, Burke, Cherokee, Clay, Graham, Haywood and 11 more	91 min
May 7, 5:17 AM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Beaufort, Bertie, Bladen, Brunswick and 58 more	118 min
May 7, 3:03 PM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Bertie, Cabarrus, Caswell, Chatham and 38 more	117 min
May 7, 6:10 PM EDT	Severe Thunderstorm Watch	SPC	Beaufort, Bladen, Brunswick, Carteret, Columbus, Craven and 21 more	6 hr
May 7, 7:33 PM EDT	Mesoscale Discussion	SPC	Beaufort, Bertie, Bladen, Brunswick, Camden, Carteret and 32 more	57 min

Nearby

Mesoscale Discussions in Virginia, 2009 Mesoscale Discussions in North Carolina, 2009 Mesoscale Discussions in Maryland, 2009 Every mesoscale discussion in 2009

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.