Alert archive / Virginia / Mesoscale Discussions in 2009

Mesoscale Discussion 775

May 9, 200913 counties in North Carolina; 36 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at May 9, 2009, 12:51 AM EDT for 13 counties in North Carolina; 36 counties in Virginia. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued: May 9, 2009, 12:51 AM EDT (04:51 UTC)
Expired: May 9, 2009, 2:15 AM EDT
In force: 84 min
Issued by: the Storm Prediction Center

All 49 counties

Caswell County, NC, Edgecombe County, NC, Franklin County, NC, Gates County, NC, Granville County, NC, Halifax County, NC, Hertford County, NC, Nash County, NC, Northampton County, NC, Person County, NC, Rockingham County, NC, Vance County, NC, Warren County, NC, Amelia County, VA, Brunswick County, VA, Campbell 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 Hopewell, VA, City of Martinsville, VA, City of Newport News, VA, City of Petersburg, VA, City of Richmond, VA, City of Suffolk, VA, City of Williamsburg, VA, Dinwiddie County, VA, Gloucester County, VA, Greensville County, VA, Halifax County, VA, Henrico County, VA, Henry County, VA, Isle of Wight County, VA, James City County, VA, Lunenburg County, VA, Mecklenburg County, VA, New Kent County, VA, Nottoway County, VA, Pittsylvania County, VA, Prince Edward County, VA, Prince George County, VA, Southampton County, VA, Surry County, VA, Sussex County, VA, York County, VA

The radar

The Norfolk radar (KAKQ), 104 km from the middle of the area, began a volume at 04:54 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.

Tornado Watch 279May 9, 1:05 AM EDT

The nearest sounding before it

Roanoke, VA (KRNK), launched 00:00Z, 4.9 hours before the alert went out and 124 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: 113 J/kg
Mixed-layer CIN: -42 J/kg
Mixed-layer LCL: 1561 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 84 m²/s²
0-3 km storm-relative helicity: 103 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.8

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 8, 8:30 PM EDT	Mesoscale Discussion	SPC	Alexander, Alleghany, Ashe, Avery, Buncombe, Burke and 19 more	90 min
May 8, 10:01 PM EDT	Tornado Watch	SPC	Caswell, Rockingham, Stokes	4 hr
May 8, 11:37 PM EDT	Mesoscale Discussion	SPC	Alleghany, Ashe, Forsyth, Rockingham, Stokes, Surry and 3 more	53 min
May 9, 12:47 PM EDT	Mesoscale Discussion	SPC	Alamance, Alexander, Burke, Cabarrus, Caldwell, Caswell and 32 more	118 min
May 9, 1:17 PM EDT	Severe Thunderstorm Watch	SPC	Alamance, Alexander, Anson, Burke, Cabarrus, Caldwell and 36 more	8 hr
May 9, 4:30 PM EDT	Mesoscale Discussion	SPC	Alamance, Cabarrus, Caswell, Catawba, Chatham, Davidson and 19 more	90 min
May 9, 5:58 PM EDT	Mesoscale Discussion	SPC	Bertie, Camden, Chatham, Chowan, Durham, Edgecombe and 20 more	62 min
May 9, 6:25 PM EDT	Severe Thunderstorm Watch	SPC	Beaufort, Bertie, Camden, Carteret, Chowan, Craven and 31 more	4 hr
May 9, 1:07 AM EDT	Tornado Watch	SPC	Amelia, Brunswick, Charles City, Chesterfield, Cumberland, Dinwiddie and 39 more	4 hr

Nearby

Mesoscale Discussions in Virginia, 2009 Mesoscale Discussions in North Carolina, 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.