Alert archive / Virginia / Mesoscale Discussions in 2007

Mesoscale Discussion 1833

August 21, 2007Saint Mary's County, Somerset County, Maryland; 56 counties in North Carolina; 94 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Aug 21, 2007, 3:51 PM EDT for Saint Mary's County, Somerset County, Maryland; 56 counties in North Carolina; 94 counties in Virginia. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued
Aug 21, 2007, 3:51 PM EDT (19:51 UTC)
Expired
Aug 21, 2007, 5:45 PM EDT
In force
114 min
Issued by
the Storm Prediction Center
All 152 counties

Saint Mary's County, MD, Somerset County, MD, Alamance County, NC, Alexander County, NC, Beaufort County, NC, Bertie County, NC, Cabarrus County, NC, Caldwell County, NC, Camden County, NC, Caswell County, NC, Catawba County, NC, Chatham County, NC, Chowan County, NC, Cumberland County, NC, Davidson County, NC, Davie County, NC, Duplin County, NC, Durham County, NC, Edgecombe County, NC, Forsyth County, NC, Franklin County, NC, Gates County, NC, Granville County, NC, Greene County, NC, Guilford County, NC, Halifax County, NC, Harnett County, NC, Hertford County, NC, Iredell County, NC, Johnston County, NC, Jones County, NC, Lee County, NC, Lenoir County, NC, Martin County, NC, Montgomery County, NC, Moore County, NC, Nash County, NC, Northampton County, NC, Orange County, NC, Pasquotank County, NC, Perquimans County, NC, Person County, NC, Pitt County, NC, Randolph County, NC, Rockingham County, NC, Rowan County, NC, Sampson County, NC, Stanly County, NC, Stokes County, NC, Surry County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Washington County, NC, Wayne County, NC, Wilkes County, NC, Wilson County, NC, Yadkin County, NC, Accomack County, VA, Albemarle County, VA, Alleghany County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Augusta County, VA, Bath County, VA, Bedford County, VA, Botetourt 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 Buena Vista, VA, City of Charlottesville, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Covington, VA, City of Danville, VA, City of Emporia, VA, City of Franklin, VA, City of Fredericksburg, VA, City of Hampton, VA, City of Harrisonburg, VA, City of Hopewell, VA, City of Lexington, VA, City of Lynchburg, VA, City of Martinsville, 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 Roanoke, VA, City of Salem, VA, City of Staunton, VA, City of Suffolk, VA, City of Virginia Beach, VA, City of Waynesboro, VA, City of Williamsburg, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fluvanna County, VA, Franklin County, VA, Gloucester County, VA, Goochland County, VA, Greene County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, Highland 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, Madison County, VA, Mathews County, VA, Mecklenburg County, VA, Middlesex County, VA, Nelson County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Nottoway County, VA, Orange County, VA, Page County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Richmond County, VA, Rockbridge County, VA, Rockingham County, VA, Southampton County, VA, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Sussex County, VA, Westmoreland County, VA, York County, VA

The radar

The Norfolk radar (KAKQ), 111 km from the middle of the area, began a volume at 19:54 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.

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 7.9 hours before the alert went out and 125 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, Roanoke, VA at 12:00Z on 2007-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 69 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, Roanoke, VA at 12:00Z on 2007-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 112 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
69 J/kg
Mixed-layer CIN
-132 J/kg
Mixed-layer LCL
1286 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
112 m²/s²
0-3 km storm-relative helicity
122 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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, 1:42 PM EDTMesoscale DiscussionSPCAlamance, Alexander, Alleghany, Ashe, Avery, Buncombe and 29 more2 hr
Aug 21, 2:12 PM EDTSevere Thunderstorm WatchSPCAlamance, Alexander, Alleghany, Ashe, Avery, Buncombe and 21 more5 hr
Aug 21, 4:23 PM EDTSevere Thunderstorm WatchSPCBertie, Camden, Chatham, Chowan, Currituck, Durham and 18 more7 hr
Aug 21, 4:56 PM EDTMesoscale DiscussionSPCAnson, Bladen, Cabarrus, Cleveland, Cumberland, Duplin and 16 more3 hr
Aug 21, 6:10 PM EDTSevere Thunderstorm WatchSPCAnson, Beaufort, Carteret, Craven, Cumberland, Dare and 18 more6 hr
Aug 21, 6:12 PM EDTMesoscale DiscussionSPCAlamance, Anson, Beaufort, Bertie, Bladen, Brunswick and 49 more2 hr

Nearby

Mesoscale Discussions in Virginia, 2007Mesoscale Discussions in North Carolina, 2007Mesoscale Discussions in Maryland, 2007Every mesoscale discussion in 2007

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.