Alert archive / Virginia / Mesoscale Discussions in 2009

Mesoscale Discussion 773

May 8, 20094 states

The Storm Prediction Center issued this mesoscale discussion at May 8, 2009, 11:37 PM EDT for 4 states. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued: May 8, 2009, 11:37 PM EDT (03:37 UTC)
Expired: May 9, 2009, 12:30 AM EDT
In force: 53 min
Issued by: the Storm Prediction Center

All 38 counties

Alleghany County, NC, Ashe County, NC, Forsyth County, NC, Rockingham County, NC, Stokes County, NC, Surry County, NC, Watauga County, NC, Wilkes County, NC, Yadkin County, NC, Johnson County, TN, Bland County, VA, Buchanan County, VA, Carroll County, 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, Floyd County, VA, Franklin County, VA, Giles County, VA, Grayson County, VA, Henry County, VA, Montgomery County, VA, Patrick County, VA, Pittsylvania County, VA, Pulaski County, VA, Roanoke County, VA, Russell County, VA, Smyth County, VA, Tazewell County, VA, Washington County, VA, Wythe County, VA, Logan County, WV, McDowell County, WV, Mercer County, WV, Wyoming County, WV

The radar

The Roanoke radar (KFCX), 64 km from the middle of the area, began a volume at 03:37 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, 3.6 hours before the alert went out and 134 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 9, 12:51 AM EDT	Mesoscale Discussion	SPC	Caswell, Edgecombe, Franklin, Gates, Granville, Halifax and 7 more	84 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 8, 11:04 PM EDT	Mesoscale Discussion	SPC	Benton, Cheatham, Clay, Davidson, Dickson, Dyer and 16 more	86 min
May 8, 11:31 PM EDT	Severe Thunderstorm Watch	SPC	Carroll, Clay, Crockett, Dyer, Fentress, Gibson and 14 more	7 hr
May 9, 3:22 AM EDT	Mesoscale Discussion	SPC	Benton, Cannon, Carroll, Cheatham, Chester, Clay and 44 more	53 min
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 Mesoscale Discussions in West Virginia, 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.