Alert archive / Virginia / Mesoscale Discussions in 2011

Mesoscale Discussion 875

May 22, 20116 counties in North Carolina; 11 counties in Virginia; Monroe County, West Virginia

The Storm Prediction Center issued this mesoscale discussion at May 22, 2011, 9:02 PM EDT for 6 counties in North Carolina; 11 counties in Virginia; Monroe County, West Virginia. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: May 22, 2011, 9:02 PM EDT (01:02 UTC)
Expired: May 22, 2011, 10:00 PM EDT
In force: 58 min
Issued by: the Storm Prediction Center

Counties Alexander County, NC, Alleghany County, NC, Catawba County, NC, Surry County, NC, Wilkes County, NC, Yadkin County, NC, Carroll County, VA, City of Galax, VA, City of Radford, VA, City of Salem, VA, Craig County, VA, Floyd County, VA, Giles County, VA, Montgomery County, VA, Patrick County, VA, Pulaski County, VA, Roanoke County, VA, Monroe County, WV

The radar

The Roanoke radar (KFCX), 78 km from the middle of the area, began a volume at 01:04 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

Greensboro/Hi Pt, NC (KGSO), launched 00:00Z, 1.0 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-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: 1111 J/kg
Mixed-layer CIN: -15 J/kg
Mixed-layer LCL: 1533 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 56 m²/s²
0-3 km storm-relative helicity: 65 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 1.2

Open this sounding in Storm Lab

The text

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

803 
ACUS11 KWNS 230102
SWOMCD
SPC MCD 230102 
VAZ000-WVZ000-NCZ000-230200-

MESOSCALE DISCUSSION 0875
NWS STORM PREDICTION CENTER NORMAN OK
0802 PM CDT SUN MAY 22 2011

AREAS AFFECTED...WRN VA/WRN NC

CONCERNING...SEVERE THUNDERSTORM WATCH 333...

VALID 230102Z - 230200Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 333
CONTINUES.

MULTICELLULAR CONVECTIVE CLUSTERS OVER WRN VA/WRN NC WILL CONTINUE
PROGRESSING EWD DURING THE NEXT COUPLE OF HOURS AMIDST MLCAPE VALUES
OF 500 TO 1000 J/KG AND EFFECTIVE BULK SHEAR MAGNITUDES OF 25 TO 35
KT. THIS WILL SUPPORT THE THREAT FOR MARGINALLY SVR HAIL AND A FEW
DMGG WIND GUSTS. HOWEVER...THE ONSET OF NOCTURNAL COOLING WILL
RESULT IN A STABILIZING BOUNDARY LAYER WITH TIME...CAUSING THE SVR
THREAT TO SUBSTANTIALLY DECREASE BY THE SCHEDULED EXPIRATION TIME OF
03Z. REGARDLESS...THE THREAT FOR MARGINALLY SVR STORMS COULD EXTEND
ONE OR TWO TIERS OF COUNTIES EAST OF WW333 DURING THE NEXT COUPLE OF
HOURS. THUS...THE WW MAY NEED TO BE LOCALLY EXTENDED IN SPATIAL
COVERAGE TO ADDRESS THIS ACTIVITY.

..COHEN.. 05/23/2011

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

ATTN...WFO...RNK...GSP...

LAT...LON   35608161 36758111 37718055 37757983 36878014 36278054
            35358136 35608161

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
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, 7:02 PM EDT	Mesoscale Discussion	SPC	Alamance, Caswell, Chatham, Davidson, Davie, Durham and 17 more	58 min
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
May 23, 7:20 PM EDT	Mesoscale Discussion	SPC	Boone, Brooke, Cabell, Calhoun, Doddridge, Jackson and 16 more	85 min

Nearby

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