Alert archive / Virginia / Mesoscale Discussions in 2018

Mesoscale Discussion 789

June 19, 201816 counties in Maryland; 19 counties in Virginia; 7 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at Jun 19, 2018, 12:04 PM EDT for 16 counties in Maryland; 19 counties in Virginia; 7 counties in West Virginia. It was in force for 116 min.

The area

The outline as issued.

The facts

Issued: Jun 19, 2018, 12:04 PM EDT (16:04 UTC)
Expired: Jun 19, 2018, 2:00 PM EDT
In force: 116 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 42 counties

Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Carroll County, MD, Charles County, MD, City of Baltimore, MD, Frederick County, 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, Washington 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, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Loudoun County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Shenandoah County, VA, Stafford County, VA, Warren County, VA, Berkeley County, WV, Grant County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV

The radar

The Sterling radar (KLWX), 19 km from the middle of the area, began a volume at 16:05 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

Pittsburgh, PA (KAGC), launched 12:00Z, 4.1 hours before the alert went out and 263 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: 362 J/kg
Mixed-layer CIN: -14 J/kg
Mixed-layer LCL: 610 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 75 m²/s²
0-3 km storm-relative helicity: 87 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.6

Open this sounding in Storm Lab

The text

As transmitted.

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Nearby

Mesoscale Discussions in Virginia, 2018 Mesoscale Discussions in Maryland, 2018 Mesoscale Discussions in West Virginia, 2018 Every mesoscale discussion in 2018

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.