Alert archive / Virginia / Mesoscale Discussions in 2012

Mesoscale Discussion 659

May 2, 20129 counties in North Carolina; 52 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at May 2, 2012, 1:41 PM EDT for 9 counties in North Carolina; 52 counties in Virginia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
May 2, 2012, 1:41 PM EDT (17:41 UTC)
Expired
May 2, 2012, 3:45 PM EDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
40%
All 61 counties

Caswell County, NC, Franklin County, NC, Granville County, NC, Halifax County, NC, Nash County, NC, Northampton County, NC, Person County, NC, Vance County, NC, Warren County, NC, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Bedford County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charlotte County, VA, Chesterfield County, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Fredericksburg, VA, City of Hopewell, VA, City of Lexington, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Petersburg, VA, City of Richmond, VA, City of Waynesboro, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Fluvanna County, VA, Franklin County, VA, Goochland County, VA, Greene County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mecklenburg County, VA, Nelson County, VA, Nottoway County, VA, Orange County, VA, Page County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Rappahannock County, VA, Spotsylvania County, VA, Sussex County, VA

The radar

The Norfolk radar (KAKQ), 127 km from the middle of the area, began a volume at 17:42 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, 5.7 hours before the alert went out and 96 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 2012-05-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 727 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 2012-05-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 120 square meters per square second.193958Sfc1 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
727 J/kg
Mixed-layer CIN
-72 J/kg
Mixed-layer LCL
813 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
120 m²/s²
0-3 km storm-relative helicity
113 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.3

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.

IssuedProductOfficeCountiesLasted
May 2, 4:56 PM EDTMesoscale DiscussionSPCClarke, Fauquier, Frederick, Loudoun, Warren, City of Winchester2 hr

Nearby

Mesoscale Discussions in Virginia, 2012Mesoscale Discussions in North Carolina, 2012Every 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.