Alert archive / Virginia / Mesoscale Discussions in 2004
Mesoscale Discussion 2191
The Storm Prediction Center issued this mesoscale discussion at Sep 8, 2004, 8:30 PM EDT for 4 states. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 8, 2004, 8:30 PM EDT (00:30 UTC)
- Expired
- Sep 8, 2004, 10:30 PM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
All 68 counties
Calvert County, MD, Carroll County, MD, Charles County, MD, Frederick County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Saint Mary's County, MD, Washington County, MD, Adams County, PA, Franklin County, PA, Fulton County, PA, Amelia County, VA, Arlington County, VA, Caroline County, VA, Charles City County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Colonial Heights, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Hopewell, VA, City of Manassas, VA, City of Manassas Park, VA, City of Petersburg, VA, City of Richmond, 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, Hanover County, VA, Henrico 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, Madison County, VA, Mathews County, VA, Middlesex County, VA, New Kent 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, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Warren County, VA, Westmoreland County, VA, York County, VA, Berkeley County, WV, Hampshire County, WV, Jefferson County, WV, Morgan County, WV
The radar
The Sterling radar (KLWX), 58 km from the middle of the area, began a volume at 00:32 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 00:00Z, 0.5 hours before the alert went out and 55 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.
- Mixed-layer CAPE
- 622 J/kg
- Mixed-layer CIN
- -2 J/kg
- Mixed-layer LCL
- 605 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 311 m²/s²
- 0-3 km storm-relative helicity
- 383 m²/s²
- Significant tornado parameter
- 1.0
- Supercell composite
- 6.9
The text
As transmitted, in the capitals the NWS used until 2016.
722 ACUS11 KWNS 090032 SWOMCD SPC MCD 090030 PAZ000-VAZ000-MDZ000-DCZ000-WVZ000-090230- MESOSCALE DISCUSSION 2191 NWS STORM PREDICTION CENTER NORMAN OK 0730 PM CDT WED SEP 08 2004 AREAS AFFECTED...ERN VA...MD...FAR ERN WV...SRN PA CONCERNING...SEVERE THUNDERSTORM POTENTIAL VALID 090030Z - 090230Z ...UPDATE FOR TORNADO WATCH 815... AN ISOLATED TORNADO THREAT WILL CONTINUE OVER THE NEXT FEW HOURS AS THE REMNANTS OF FRANCES MOVES NWD ACROSS THE MID-ATLANTIC STATES. SFC ANALYSIS SHOWS THE CENTER OF TROPICAL DEPRESSION FRANCES OVER WV WITH STRONG MOISTURE ADVECTION OCCURRING ACROSS VA WHERE SFC DEWPOINTS ARE IN THE MID 70S F. THIS IS CREATING LCL HEIGHTS AROUND 500 METERS. IN ADDITION...FORECAST SOUNDINGS FOR NRN VA THIS EVENING SHOW STRONGLY VEERED LOW-LEVEL WIND PROFILES AND THIS COMBINED WITH LOW LCL HEIGHTS WILL BE FAVORABLE FOR TORNADOES WITH MINI-SUPERCELLS THAT DEVELOP AND MOVE NWD. HOWEVER...INSTABILITY IS DECREASING ACROSS THE REGION AND THIS WILL BE A LIMITING FACTOR AS THE EVENING PROGRESSES. AS A RESULT...THE TORNADO THREAT SHOULD GRADUALLY DECREASE BY THE LATE EVENING HOURS ..BROYLES.. 09/09/2004 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...AKQ...CTP...LWX... 37087671 37057785 37347812 38227831 39397865 39937862 40217793 40117712 39597680 38187633 37297622
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 9, 2:05 AM EDT | Mesoscale Discussion | SPC | Anne Arundel, Baltimore, Calvert, Caroline, Cecil, Dorchester and 8 more | 2 hr |
Nearby
Mesoscale Discussions in Virginia, 2004Mesoscale Discussions in Maryland, 2004Mesoscale Discussions in West Virginia, 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.