Alert archive / Virginia / Mesoscale Discussions in 2011

Mesoscale Discussion 2122

September 4, 2011Garrett County, Maryland; 31 counties in Virginia; 27 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at Sep 4, 2011, 3:15 PM EDT for Garrett County, Maryland; 31 counties in Virginia; 27 counties in West Virginia. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued
Sep 4, 2011, 3:15 PM EDT (19:15 UTC)
Expired
Sep 4, 2011, 4:15 PM EDT
In force
60 min
Issued by
the Storm Prediction Center
All 59 counties

Garrett County, MD, Alleghany County, VA, Augusta County, VA, Bath County, VA, Bland County, VA, Botetourt County, VA, Buchanan County, VA, City of Buena Vista, VA, City of Covington, VA, City of Harrisonburg, VA, City of Lexington, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, City of Staunton, VA, City of Waynesboro, VA, Craig County, VA, Giles County, VA, Grayson County, VA, Highland County, VA, Montgomery County, VA, Page County, VA, Pulaski County, VA, Roanoke County, VA, Rockbridge County, VA, Rockingham County, VA, Russell County, VA, Shenandoah County, VA, Smyth County, VA, Tazewell County, VA, Washington County, VA, Wythe County, VA, Barbour County, WV, Braxton County, WV, Clay County, WV, Fayette County, WV, Gilmer County, WV, Grant County, WV, Greenbrier County, WV, Hampshire County, WV, Hardy County, WV, Harrison County, WV, Lewis County, WV, McDowell County, WV, Mercer County, WV, Mineral County, WV, Monroe County, WV, Nicholas County, WV, Pendleton County, WV, Pocahontas County, WV, Preston County, WV, Raleigh County, WV, Randolph County, WV, Summers County, WV, Taylor County, WV, Tucker County, WV, Upshur County, WV, Webster County, WV, Wyoming County, WV

The radar

The Roanoke radar (KFCX), 119 km from the middle of the area, began a volume at 19:16 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

Roanoke, VA (KRNK), launched 12:00Z, 7.3 hours before the alert went out and 122 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-pSkew-T log-p diagram, Roanoke, VA at 12:00Z on 2011-09-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 259 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Roanoke, VA at 12:00Z on 2011-09-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 19 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
259 J/kg
Mixed-layer CIN
-195 J/kg
Mixed-layer LCL
720 m above ground
0-6 km bulk shear
11 kt
0-1 km storm-relative helicity
19 m²/s²
0-3 km storm-relative helicity
32 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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Nearby

Mesoscale Discussions in Virginia, 2011Mesoscale Discussions in West Virginia, 2011Mesoscale Discussions in Maryland, 2011Every mesoscale discussion in 2011

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.