Alert archive / Maryland / Mesoscale Discussions in 2026

Mesoscale Discussion 2199

September 2, 202612 counties in Maryland; 9 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Sep 2, 2026, 1:21 PM EDT for 12 counties in Maryland; 9 counties in Virginia. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued: Sep 2, 2026, 1:21 PM EDT (17:21 UTC)
Expired: Sep 2, 2026, 2:45 PM EDT
In force: 84 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 643

All 21 counties

Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Charles County, MD, City of Baltimore, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Talbot County, MD, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Manassas, VA, City of Manassas Park, VA, Fairfax County, VA, Loudoun County, VA, Prince William County, VA

The radar

The Sterling radar (KLWX), 60 km from the middle of the area, began a volume at 17:21 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 12:00Z, 5.4 hours before the alert went out and 53 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 394 J/kg
Mixed-layer CIN: -133 J/kg
Mixed-layer LCL: 1089 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 49 m²/s²
0-3 km storm-relative helicity: 35 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 1, 9:46 PM EDT	Mesoscale Discussion	SPC	Caroline, Cecil, Wicomico, Worcester	119 min
Sep 2, 11:09 AM EDT	Mesoscale Discussion	SPC	Anne Arundel, Baltimore, Carroll, Frederick, Harford, Howard and 7 more	66 min
Sep 2, 11:46 AM EDT	Severe Thunderstorm Watch	SPC	Allegany, Anne Arundel, Baltimore, Calvert, Caroline, Carroll and 13 more	5 hr

Nearby

Mesoscale Discussions in Maryland, 2026 Mesoscale Discussions in Virginia, 2026 Every 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.