Alert archive / Virginia / Mesoscale Discussions in 2004

Mesoscale Discussion 2070

August 21, 200428 counties in North Carolina; 48 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Aug 21, 2004, 2:20 PM EDT for 28 counties in North Carolina; 48 counties in Virginia. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued
Aug 21, 2004, 2:20 PM EDT (18:20 UTC)
Expired
Aug 21, 2004, 4:15 PM EDT
In force
115 min
Issued by
the Storm Prediction Center
All 76 counties

Alamance County, NC, Alexander County, NC, Burke County, NC, Cabarrus County, NC, Caswell County, NC, Catawba County, NC, Chatham County, NC, Davidson County, NC, Davie County, NC, Durham County, NC, Forsyth County, NC, Franklin County, NC, Gaston County, NC, Granville County, NC, Guilford County, NC, Iredell County, NC, Lincoln County, NC, Orange County, NC, Person County, NC, Randolph County, NC, Rockingham County, NC, Rowan County, NC, Stokes County, NC, Surry County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Yadkin County, NC, 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 Fredericksburg, VA, City of Hopewell, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Petersburg, VA, City of Richmond, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fluvanna County, VA, Franklin County, VA, Goochland County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, James City County, VA, King and Queen County, VA, King William County, VA, Louisa County, VA, Lunenburg County, VA, Mecklenburg County, VA, Middlesex County, VA, New Kent County, VA, Nottoway County, VA, Orange County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Richmond County, VA, Spotsylvania County, VA, Sussex County, VA, Westmoreland County, VA

The radar

The Norfolk radar (KAKQ), 117 km from the middle of the area, began a volume at 18:21 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 6.3 hours before the alert went out and 249 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-pSkew-T log-p diagram, Washington/Dulle, VA at 12:00Z on 2004-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 545 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2004-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 74 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
545 J/kg
Mixed-layer CIN
-109 J/kg
Mixed-layer LCL
1174 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
74 m²/s²
0-3 km storm-relative helicity
107 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.6

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.

IssuedProductOfficeCountiesLasted
Aug 21, 1:24 PM EDTMesoscale DiscussionSPCBeaufort, Bertie, Bladen, Brunswick, Camden, Chowan and 23 more2 hr
Aug 21, 1:55 PM EDTSevere Thunderstorm WatchSPCBeaufort, Bertie, Bladen, Camden, Carteret, Chowan and 25 more6 hr

Nearby

Mesoscale Discussions in Virginia, 2004Mesoscale Discussions in North Carolina, 2004Every mesoscale discussion in 2004

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.