Alert archive / Virginia / Mesoscale Discussions in 2011

Mesoscale Discussion 923

May 24, 201130 counties in North Carolina; 47 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at May 24, 2011, 12:15 PM EDT for 30 counties in North Carolina; 47 counties in Virginia. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued: May 24, 2011, 12:15 PM EDT (16:15 UTC)
Expired: May 24, 2011, 1:45 PM EDT
In force: 90 min
Issued by: the Storm Prediction Center

All 77 counties

Alamance County, NC, Bertie County, NC, Camden County, NC, Caswell County, NC, Chowan County, NC, Durham County, NC, Edgecombe County, NC, Forsyth County, NC, Franklin County, NC, Gates County, NC, Granville County, NC, Greene County, NC, Guilford County, NC, Halifax County, NC, Hertford County, NC, Martin County, NC, Nash County, NC, Northampton County, NC, Orange County, NC, Pasquotank County, NC, Perquimans County, NC, Person County, NC, Pitt County, NC, Rockingham County, NC, Stokes County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Washington County, NC, Wilson County, NC, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Bedford County, VA, Botetourt County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Charlotte County, VA, Chesterfield County, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Franklin, VA, City of Hopewell, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Petersburg, VA, City of Portsmouth, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, City of Suffolk, VA, City of Virginia Beach, VA, Cumberland County, VA, Dinwiddie County, VA, Floyd County, VA, Franklin County, VA, Greensville County, VA, Halifax County, VA, Henry County, VA, Isle of Wight County, VA, Lunenburg County, VA, Mecklenburg County, VA, Montgomery County, VA, Nottoway County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Pulaski County, VA, Roanoke County, VA, Southampton County, VA, Surry County, VA, Sussex County, VA

The radar

The Raleigh/Durham radar (KRAX), 108 km from the middle of the area, began a volume at 16:15 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 355May 24, 12:40 PM EDT

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 4.3 hours before the alert went out and 109 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: 354 J/kg
Mixed-layer CIN: -64 J/kg
Mixed-layer LCL: 922 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 148 m²/s²
0-3 km storm-relative helicity: 210 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.9

Open this sounding in Storm Lab

The text

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

217 
ACUS11 KWNS 241615
SWOMCD
SPC MCD 241615 
NCZ000-VAZ000-241745-

MESOSCALE DISCUSSION 0923
NWS STORM PREDICTION CENTER NORMAN OK
1115 AM CDT TUE MAY 24 2011

AREAS AFFECTED...VA AND NC

CONCERNING...SEVERE THUNDERSTORM WATCH 354...

VALID 241615Z - 241745Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 354
CONTINUES.

THE SEVERE THREAT ONGOING IN THE ERN PART OF WW 354 WILL LIKELY
DEVELOP EWD INTO SE VA AND NRN NC THIS AFTERNOON. WIND DAMAGE AND
HAIL SHOULD ACCOMPANY THE STRONGER THUNDERSTORMS. WW ISSUANCE WILL
PROBABLY BE NEEDED DOWNSTREAM OF THE CURRENT SEVERE THUNDERSTORM
WATCH WITHIN THE HOUR.

A CLUSTER OF STRONG THUNDERSTORMS IN WRN VA IS LOCATED JUST AHEAD OF
A SHORTWAVE TROUGH EVIDENT ON WATER VAPOR IMAGERY. THIS FEATURE WILL
SUPPORT THE CONVECTION EWD THIS AFTERNOON INTO AN INCREASINGLY
UNSTABLE AIRMASS. MESOANALYSIS SHOWS MLCAPE VALUES IN SE VA AND NE
NC IN THE 1000 TO 2000 J/KG RANGE. IN ADDITION...LOW-LEVEL LAPSE
RATES IN THE APPALACHIAN FOOTHILLS ARE NOW ESTIMATED TO BETWEEN 7.5
AND 8.0 C/KM ALONG THE WRN EDGE OF MODERATE INSTABILITY. THIS
SUGGESTS THE DEVELOPING STORMS MAY HAVE AN INCREASING WIND DAMAGE
THREAT. THE WIND DAMAGE THREAT COULD BECOME ENHANCED IF A PERSISTENT
LINE-SEGMENT CAN ORGANIZE ACROSS THE REGION.

..BROYLES.. 05/24/2011

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...AKQ...MHX...LWX...RAH...RNK...

LAT...LON   37647972 37048077 35958035 35647875 35377712 35997607
            36797598 37657796 37647972

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 24, 8:34 AM EDT	Mesoscale Discussion	SPC	Alamance, Alexander, Alleghany, Ashe, Avery, Caldwell and 13 more	116 min
May 24, 10:00 AM EDT	Severe Thunderstorm Watch	SPC	Alleghany, Ashe, Caswell, Rockingham, Stokes, Surry and 3 more	7 hr
May 24, 12:42 PM EDT	Severe Thunderstorm Watch	SPC	Alamance, Bertie, Camden, Chowan, Currituck, Durham and 20 more	5 hr
May 24, 3:33 PM EDT	Mesoscale Discussion	SPC	Alamance, Alexander, Alleghany, Ashe, Avery, Bertie and 30 more	87 min
May 24, 4:43 PM EDT	Tornado Watch	SPC	Alamance, Alleghany, Ashe, Caswell, Forsyth, Guilford and 8 more	5 hr
May 24, 7:33 PM EDT	Mesoscale Discussion	SPC	Alamance, Alleghany, Ashe, Caswell, Durham, Forsyth and 11 more	57 min
May 24, 7:01 AM EDT	Severe Thunderstorm Watch	SPC	Lee, Russell, Scott, Washington, Wise, City of Bristol and 1 more	8 hr
May 24, 12:55 PM EDT	Mesoscale Discussion	SPC	Lee, Scott, Wise, City of Norton	65 min
May 24, 1:57 PM EDT	Severe Thunderstorm Watch	SPC	Buchanan, Dickenson, Lee, Russell, Scott, Washington and 3 more	6 hr
May 24, 4:27 PM EDT	Mesoscale Discussion	SPC	Buchanan, Dickenson, Lee, Russell, Scott, Tazewell and 4 more	63 min
May 24, 7:46 PM EDT	Mesoscale Discussion	SPC	Lee, Russell, Scott, Washington, Wise, City of Bristol and 1 more	59 min

Nearby

Mesoscale Discussions in Virginia, 2011 Mesoscale Discussions in North Carolina, 2011 Every 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.