Alert archive / Virginia / Mesoscale Discussions in 2004

Mesoscale Discussion 2238

September 17, 20044 states

The Storm Prediction Center issued this mesoscale discussion at Sep 17, 2004, 6:19 PM EDT for 4 states. It was in force for 116 min.

The area

The outline as issued.

The facts

Issued
Sep 17, 2004, 6:19 PM EDT (22:19 UTC)
Expired
Sep 17, 2004, 8:15 PM EDT
In force
116 min
Issued by
the Storm Prediction Center
All 99 counties

Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Carroll County, MD, Charles County, MD, City of Baltimore, MD, Frederick County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Saint Mary's County, MD, Washington County, MD, Beaufort County, NC, Bertie County, NC, Camden County, NC, Chowan County, NC, Craven County, NC, Currituck County, NC, Dare County, NC, Gates County, NC, Halifax County, NC, Hertford County, NC, Hyde County, NC, Martin County, NC, Northampton County, NC, Pamlico County, NC, Pasquotank County, NC, Perquimans County, NC, Pitt County, NC, Tyrrell County, NC, Washington County, NC, Arlington County, VA, Caroline County, VA, Charles City County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Emporia, VA, City of Fairfax, VA, City of Falls Church, VA, City of Franklin, VA, City of Fredericksburg, VA, City of Hampton, VA, City of Hopewell, VA, City of Manassas, VA, City of Manassas Park, 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 Suffolk, VA, City of Virginia Beach, VA, City of Williamsburg, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Dinwiddie County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Frederick 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, Loudoun County, VA, Louisa County, VA, Mathews County, VA, Middlesex County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Orange County, VA, Powhatan County, VA, Prince George County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Southampton County, VA, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Sussex County, VA, Warren County, VA, Westmoreland County, VA, York County, VA, Berkeley County, WV, Jefferson County, WV, Morgan County, WV

The radar

The Norfolk radar (KAKQ), 13 km from the middle of the area, began a volume at 22:22 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

Wallops Is Stn, VA (KWAL), launched 12:00Z, 10.3 hours before the alert went out and 185 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, Wallops Is Stn, VA at 12:00Z on 2004-09-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 516 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, Wallops Is Stn, VA at 12:00Z on 2004-09-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 60 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
516 J/kg
Mixed-layer CIN
-13 J/kg
Mixed-layer LCL
576 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
60 m²/s²
0-3 km storm-relative helicity
20 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.4

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
Sep 17, 12:33 PM EDTMesoscale DiscussionSPCCharles, Saint Mary's117 min
Sep 17, 1:15 PM EDTTornado WatchSPCAnne Arundel, Calvert, Charles, Prince George's, Saint Mary's7 hr
Sep 17, 3:33 PM EDTMesoscale DiscussionSPCAnne Arundel, Baltimore, Carroll, Frederick, Harford, Howard and 1 more117 min
Sep 17, 3:50 PM EDTTornado WatchSPCAnne Arundel, Baltimore, Carroll, Frederick, Harford, Howard and 3 more4 hr
Sep 17, 3:53 PM EDTMesoscale DiscussionSPCCalvert, Charles, Prince George's, Saint Mary's2 hr
Sep 17, 6:50 PM EDTTornado WatchSPCAnne Arundel, Baltimore, Calvert, Caroline, Carroll, Cecil and 14 more5 hr
Sep 16, 8:45 PM EDTTornado WatchSPCCabarrus, Cleveland, Gaston, Lincoln, Mecklenburg, Polk and 1 more6 hr
Sep 16, 11:42 PM EDTMesoscale DiscussionSPCGaston, Mecklenburg2 hr
Sep 17, 1:51 AM EDTMesoscale DiscussionSPCAlexander, Burke, Caldwell, Catawba, Cleveland, Gaston and 6 more84 min
Sep 17, 9:26 AM EDTMesoscale DiscussionSPCAlamance, Anson, Bladen, Caswell, Chatham, Cumberland and 24 more2 hr
Sep 17, 10:10 AM EDTTornado WatchSPCAlamance, Anson, Bladen, Brunswick, Caswell, Chatham and 37 more7 hr
Sep 17, 11:03 AM EDTMesoscale DiscussionSPCAlamance, Bertie, Caswell, Chatham, Cumberland, Durham and 26 more87 min
Sep 17, 1:37 PM EDTMesoscale DiscussionSPCAlamance, Bladen, Brunswick, Caswell, Chatham, Columbus and 29 more113 min
Sep 17, 4:01 PM EDTMesoscale DiscussionSPCBladen, Brunswick, Columbus, Cumberland, Duplin, Franklin and 6 more59 min
Sep 17, 4:35 PM EDTTornado WatchSPCBladen, Brunswick, Columbus, Duplin, Edgecombe, Franklin and 14 more3 hr
Sep 17, 7:23 PM EDTMesoscale DiscussionSPCDuplin, Edgecombe, Greene, Halifax, Lenoir, Nash and 4 more37 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; radar from the NEXRAD Level II archive.