Alert archive / Virginia / Mesoscale Discussions in 2012

Mesoscale Discussion 1400

July 5, 20124 counties in Maryland; 7 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Jul 5, 2012, 3:29 AM EDT for 4 counties in Maryland; 7 counties in Virginia. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Jul 5, 2012, 3:29 AM EDT (07:29 UTC)
Expired: Jul 5, 2012, 5:00 AM EDT
In force: 91 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Calvert County, MD, Charles County, MD, Saint Mary's County, MD, Somerset County, MD, Essex County, VA, King George County, VA, Lancaster County, VA, Northumberland County, VA, Richmond County, VA, Stafford County, VA, Westmoreland County, VA

The radar

The Sterling radar (KLWX), 111 km from the middle of the area, began a volume at 07:29 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, 7.5 hours before the alert went out and 104 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: 2993 J/kg
Mixed-layer CIN: -17 J/kg
Mixed-layer LCL: 1701 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 27 m²/s²
0-3 km storm-relative helicity: 107 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 4, 8:05 PM EDT	Mesoscale Discussion	SPC	Allegany, Garrett, Washington	55 min
Jul 5, 4:37 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Baltimore, Carroll, Cecil, Frederick, Harford and 6 more	113 min
Jul 5, 11:14 AM EDT	Mesoscale Discussion	SPC	Bland, Buchanan, Dickenson, Grayson, Lee, Russell and 9 more	91 min
Jul 5, 11:37 AM EDT	Severe Thunderstorm Watch	SPC	Bland, Buchanan, Carroll, Craig, Dickenson, Floyd and 20 more	7 hr
Jul 5, 1:40 PM EDT	Mesoscale Discussion	SPC	Brunswick, Charles City, Dinwiddie, Greensville, Henrico, Isle of Wight and 13 more	95 min
Jul 5, 2:57 PM EDT	Mesoscale Discussion	SPC	Alleghany, Bland, Botetourt, Buchanan, Carroll, Craig and 23 more	2 hr

Nearby

Mesoscale Discussions in Virginia, 2012 Mesoscale Discussions in Maryland, 2012 Every mesoscale discussion in 2012

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.