Alert archive / Virginia / Mesoscale Discussions in 2004

Mesoscale Discussion 1556

July 7, 2004Calvert County, Charles County, Saint Mary's County, Maryland; 13 counties in North Carolina; 52 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Jul 7, 2004, 11:49 AM EDT for Calvert County, Charles County, Saint Mary's County, Maryland; 13 counties in North Carolina; 52 counties in Virginia. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued
Jul 7, 2004, 11:49 AM EDT (15:49 UTC)
Expired
Jul 7, 2004, 12:45 PM EDT
In force
56 min
Issued by
the Storm Prediction Center
All 68 counties

Calvert County, MD, Charles County, MD, Saint Mary's County, MD, Bertie County, NC, Chowan County, NC, Edgecombe County, NC, Franklin County, NC, Gates County, NC, Halifax County, NC, Hertford County, NC, Martin County, NC, Nash County, NC, Northampton County, NC, Vance County, NC, Warren County, NC, Wilson County, NC, Amelia County, VA, Brunswick County, VA, Caroline County, VA, Charles City County, VA, Chesterfield County, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Emporia, VA, City of Franklin, VA, City of Fredericksburg, VA, City of Hampton, VA, City of Hopewell, VA, City of Newport News, 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, 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, Northumberland County, VA, Nottoway County, VA, Powhatan County, VA, Prince George County, VA, Richmond County, VA, Southampton County, VA, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Sussex County, VA, Westmoreland County, VA, York County, VA

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, 3.8 hours before the alert went out and 179 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 2004-07-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 176 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 2004-07-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 20 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
176 J/kg
Mixed-layer CIN
-139 J/kg
Mixed-layer LCL
1284 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
20 m²/s²
0-3 km storm-relative helicity
37 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
Jul 7, 1:15 PM EDTSevere Thunderstorm WatchSPCAnne Arundel, Baltimore, Calvert, Carroll, Cecil, Charles and 11 more5 hr
Jul 7, 2:35 PM EDTMesoscale DiscussionSPCAnne Arundel, Baltimore, Calvert, Carroll, Cecil, Charles and 11 more55 min

Nearby

Mesoscale Discussions in Virginia, 2004Mesoscale Discussions in North Carolina, 2004Mesoscale Discussions in Maryland, 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.