Alert archive / Virginia / Mesoscale Discussions in 2023

Mesoscale Discussion 1749

July 28, 202312 counties in Maryland; 40 counties in Virginia; 4 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at Jul 28, 2023, 1:54 PM EDT for 12 counties in Maryland; 40 counties in Virginia; 4 counties in West Virginia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jul 28, 2023, 1:54 PM EDT (17:54 UTC)
Expired: Jul 28, 2023, 4:00 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 20%

All 56 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, Albemarle County, VA, Arlington County, VA, Augusta County, VA, Bath County, VA, Caroline County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Frederick County, VA, Greene County, VA, Highland County, VA, King George County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Nelson County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Westmoreland County, VA, Berkeley County, WV, Hardy County, WV, Jefferson County, WV, Pendleton County, WV

The radar

The Sterling radar (KLWX), 56 km from the middle of the area, began a volume at 17:54 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.

Severe Thunderstorm Watch 558Jul 28, 4:45 PM EDT

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 5.9 hours before the alert went out and 59 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: 945 J/kg
Mixed-layer CIN: -117 J/kg
Mixed-layer LCL: 1259 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 7 m²/s²
0-3 km storm-relative helicity: 114 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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
Jul 28, 4:12 PM EDT	Mesoscale Discussion	SPC	Garrett	93 min
Jul 28, 4:48 PM EDT	Severe Thunderstorm Watch	SPC	Allegany, Anne Arundel, Baltimore, Calvert, Carroll, Cecil and 10 more	5 hr
Jul 28, 6:33 PM EDT	Mesoscale Discussion	SPC	Baltimore, Carroll, Frederick, Howard, Montgomery, Washington and 1 more	87 min
Jul 28, 7:54 PM EDT	Mesoscale Discussion	SPC	Caroline, Cecil, Kent, Queen Anne's, Talbot	96 min
Jul 28, 12:35 PM EDT	Mesoscale Discussion	SPC	Brooke, Cabell, Hancock, Jackson, Lincoln, Marshall and 10 more	85 min
Jul 28, 2:18 PM EDT	Severe Thunderstorm Watch	SPC	Barbour, Boone, Braxton, Brooke, Cabell, Calhoun and 36 more	6 hr

Nearby

Mesoscale Discussions in Virginia, 2023 Mesoscale Discussions in Maryland, 2023 Mesoscale Discussions in West Virginia, 2023 Every mesoscale discussion in 2023

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.