Alert archive / Virginia / Mesoscale Discussions in 2011

Mesoscale Discussion 907

May 23, 201123 counties in North Carolina; 46 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at May 23, 2011, 7:02 PM EDT for 23 counties in North Carolina; 46 counties in Virginia. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: May 23, 2011, 7:02 PM EDT (23:02 UTC)
Expired: May 23, 2011, 8:00 PM EDT
In force: 58 min
Issued by: the Storm Prediction Center

All 69 counties

Alamance County, NC, Caswell County, NC, Chatham County, NC, Davidson County, NC, Davie County, NC, Durham County, NC, Forsyth County, NC, Franklin County, NC, Granville County, NC, Guilford County, NC, Halifax County, NC, Johnston County, NC, Lee County, NC, Nash County, NC, Orange County, NC, Person County, NC, Randolph County, NC, Rockingham County, NC, Rowan County, NC, Stokes County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Amelia County, VA, Appomattox County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Hopewell, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Petersburg, VA, City of Richmond, VA, City of Williamsburg, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fluvanna County, VA, Goochland County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, James City County, VA, King and Queen County, VA, King William County, VA, Lancaster County, VA, Louisa County, VA, Lunenburg County, VA, Mecklenburg County, VA, Middlesex County, VA, Nelson County, VA, New Kent County, VA, Northumberland County, VA, Nottoway County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Richmond County, VA, Surry County, VA, Sussex County, VA

The radar

The Roanoke radar (KFCX), 132 km from the middle of the area, began a volume at 23:04 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, 11.0 hours before the alert went out and 69 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: 264 J/kg
Mixed-layer CIN: -138 J/kg
Mixed-layer LCL: 632 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 181 m²/s²
0-3 km storm-relative helicity: 183 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.8

Open this sounding in Storm Lab

The text

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

533 
ACUS11 KWNS 232302
SWOMCD
SPC MCD 232302 
MDZ000-VAZ000-NCZ000-240000-

MESOSCALE DISCUSSION 0907
NWS STORM PREDICTION CENTER NORMAN OK
0602 PM CDT MON MAY 23 2011

AREAS AFFECTED...ERN/SRN VA...NRN NC

CONCERNING...SEVERE THUNDERSTORM WATCH 344...

VALID 232302Z - 240000Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 344
CONTINUES.

WV IMAGERY CONTINUES TO SHOW AN UPPER IMPULSE RAPIDLY MOVING E
ACROSS THE UPR OH VALLEY. ASCENT ASSOCIATED WITH THIS FEATURE WILL
GRAZE PORTIONS OF ERN/SRN VA AND NRN NC DURING THE NEXT FEW
HRS...THOUGH STORM COVERAGE WILL LIKELY REMAIN ISOLATED WITH THE
LOSS OF DAYTIME HEATING. ONGOING STORMS AS WELL AS ADDITIONAL
DEVELOPMENT WILL CONTINUE TO POSE A SVR WEATHER THREAT GIVEN
WARM/MOIST BOUNDARY LAYER WITH MLCAPE VALUES LOCALLY IN EXCESS OF
2000 J/KG...AND EFFECTIVE BULK SHEAR VALUES AROUND 35 KT. THIS
ENVIRONMENT WILL FAVOR STRONG/SVR MULTICELL AND SUPERCELL
DEVELOPMENT POSING A THREAT FOR LARGE HAIL/DAMAGING WINDS AND
PERHAPS A BRIEF TORNADO THROUGH THE EVENING.

..GARNER.. 05/23/2011

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

ATTN...WFO...AKQ...LWX...RAH...RNK...GSP...

LAT...LON   37997869 37997602 35417841 35438097 36797999 37997869

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 22, 9:02 PM EDT	Mesoscale Discussion	SPC	Alexander, Alleghany, Catawba, Surry, Wilkes, Yadkin	58 min
May 23, 2:33 PM EDT	Mesoscale Discussion	SPC	Alamance, Caswell, Chatham, Davidson, Durham, Forsyth and 9 more	87 min
May 23, 3:16 PM EDT	Severe Thunderstorm Watch	SPC	Alamance, Alexander, Alleghany, Ashe, Avery, Bertie and 41 more	7 hr
May 23, 10:33 AM EDT	Mesoscale Discussion	SPC	Albemarle, Arlington, Augusta, Clarke, Culpeper, Fairfax and 26 more	87 min
May 23, 10:48 AM EDT	Severe Thunderstorm Watch	SPC	Albemarle, Arlington, Augusta, Clarke, Culpeper, Fairfax and 28 more	9 hr
May 23, 4:40 PM EDT	Mesoscale Discussion	SPC	Arlington, Clarke, Culpeper, Fairfax, Fauquier, Loudoun and 8 more	95 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.