Alert archive / Virginia / Mesoscale Discussions in 2026
Mesoscale Discussion 2221
The Storm Prediction Center issued this mesoscale discussion at Sep 3, 2026, 6:19 PM EDT for 4 states. It was in force for 116 min.
The area
The outline as issued.
The facts
- Issued
- Sep 3, 2026, 6:19 PM EDT (22:19 UTC)
- Expired
- Sep 3, 2026, 8:15 PM EDT
- In force
- 116 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
All 75 counties
Allegany County, MD, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Carroll County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Frederick County, MD, Garrett County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Somerset County, MD, Talbot County, MD, Washington County, MD, Adams County, PA, Bedford County, PA, Blair County, PA, Cambria County, PA, Cumberland County, PA, Fayette County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Indiana County, PA, Mifflin County, PA, Somerset County, PA, Westmoreland County, PA, York County, PA, Arlington County, VA, Caroline County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Loudoun County, VA, Madison County, VA, Middlesex County, VA, Northumberland County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Westmoreland County, VA, Berkeley County, WV, Grant County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV, Preston County, WV
The radar
The Sterling radar (KLWX), 34 km from the middle of the area, began a volume at 22:18 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
Washington/Dulle, VA (KIAD), launched 12:00Z, 10.3 hours before the alert went out and 40 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
- 619 J/kg
- Mixed-layer CIN
- -74 J/kg
- Mixed-layer LCL
- 470 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km storm-relative helicity
- 55 m²/s²
- 0-3 km storm-relative helicity
- 104 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 1.9
The text
As transmitted.
455
ACUS11 KWNS 032219
SWOMCD
SPC MCD 032219
MDZ000-VAZ000-PAZ000-DCZ000-WVZ000-040015-
Mesoscale Discussion 2221
NWS Storm Prediction Center Norman OK
0519 PM CDT Thu Sep 03 2026
Areas affected...Portions of the Mid-Atlantic
Concerning...Severe potential...Watch likely
Valid 032219Z - 040015Z
Probability of Watch Issuance...80 percent
SUMMARY...Ongoing Mesoscale Convective Systems will continue to move
southeast this evening. The airmass ahead of these storms remains
very hot and unstable. A wind damage threat is expected to persist
into the greater Washington D.C. area later this evening. As such, a
new watch will likely be needed.
DISCUSSION...Multiple southeast moving mesoscale convective systems
(MCS) are ongoing across portions of northern/eastern Ohio and
western Pennsylvania. The leading MCS is currently located across
the greater Pittsburgh area, with the trailing MCS across moving
across northern Ohio and southern Lake Erie.
Effective layer shear across these linear MCSs is characterized by
30-40 knots, which is more than sufficient to support ongoing
organization as the clusters move southeast. Additionally, the
airmass ahead of these storms remains very hot and humid, with
surface temperatures in the 90Fs and dewpoints in the low-to-mid
70Fs. The result is steep low-level lapse rates and MUCAPE in excess
of 3000 J/kg ahead of these storms, all the way into the greater
Washington D.C. area.
As evening progresses and the boundary layer cools, low-level lapse
rates will weaken. However, the degree of thunderstorm organization
and the very unstable environment ahead of the MCSs will maintain a
threat for damaging wind well into the evening hours. A new watch
will likely be needed to the southeast of ongoing watches across
Pennsylvania, Ohio, and West Virginia.
..Marsh/Smith.. 09/03/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PHI...AKQ...CTP...LWX...PBZ...RLX...
LAT...LON 40907856 40647769 39867645 39817644 39007592 38017562
37607609 37527666 37797754 38477871 38967941 39727985
40487948 40907856
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 INSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 3, 4:16 PM EDT | Mesoscale Discussion | SPC | Allegany, Washington | 119 min |
| Sep 3, 4:33 PM EDT | Severe Thunderstorm Watch | SPC | Allegany, Garrett | 6 hr |
| Sep 2, 8:48 PM EDT | Mesoscale Discussion | SPC | Bradford, Cameron, Centre, Clarion, Clearfield, Clinton and 19 more | 87 min |
| Sep 3, 2:07 AM EDT | Mesoscale Discussion | SPC | Armstrong, Blair, Butler, Cambria, Cameron, Centre and 22 more | 113 min |
| Sep 3, 1:44 PM EDT | Mesoscale Discussion | SPC | Butler, Crawford, Erie, Lawrence, Mercer, Venango | 3 hr |
| Sep 3, 3:03 PM EDT | Severe Thunderstorm Watch | SPC | Allegheny, Armstrong, Beaver, Butler, Clarion, Crawford and 11 more | 9 hr |
| Sep 3, 6:13 PM EDT | Mesoscale Discussion | SPC | Allegheny, Armstrong, Cambria, Fayette, Indiana, Somerset and 2 more | 92 min |
Nearby
Mesoscale Discussions in Virginia, 2026Mesoscale Discussions in Maryland, 2026Mesoscale Discussions in Pennsylvania, 2026Every mesoscale discussion in 2026
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.