Alert archive / Virginia / Mesoscale Discussions in 2021

Mesoscale Discussion 1351

July 26, 202116 counties in North Carolina; 55 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Jul 26, 2021, 3:29 PM EDT for 16 counties in North Carolina; 55 counties in Virginia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Jul 26, 2021, 3:29 PM EDT (19:29 UTC)
Expired
Jul 26, 2021, 5:30 PM EDT
In force
2 hr
Issued by
the Storm Prediction Center
Concerning
Severe thunderstorm watch 392
All 71 counties

Alamance County, NC, Caswell County, NC, Davidson County, NC, Durham County, NC, Forsyth County, NC, Granville County, NC, Guilford County, NC, Northampton County, NC, Orange County, NC, Person County, NC, Randolph County, NC, Rockingham County, NC, Stokes County, NC, Vance County, NC, Warren County, NC, Yadkin 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, Charles City 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 Franklin, VA, City of Hopewell, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Newport News, VA, City of Petersburg, VA, City of Poquoson, VA, City of Portsmouth, VA, City of Richmond, VA, City of Suffolk, VA, City of Williamsburg, VA, Cumberland County, VA, Dinwiddie County, VA, Fluvanna County, VA, Franklin County, VA, Goochland County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, Isle of Wight County, VA, James City County, VA, King William County, VA, Louisa County, VA, Lunenburg County, VA, Mecklenburg County, VA, Nelson County, VA, New Kent County, VA, Nottoway County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Southampton County, VA, Surry County, VA, Sussex County, VA, York County, VA

The radar

The Norfolk radar (KAKQ), 126 km from the middle of the area, began a volume at 19:33 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, 7.5 hours before the alert went out and 101 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 2021-07-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 658 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 2021-07-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 30 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
658 J/kg
Mixed-layer CIN
-44 J/kg
Mixed-layer LCL
838 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
30 m²/s²
0-3 km storm-relative helicity
50 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

223 
ACUS11 KWNS 261930
SWOMCD
SPC MCD 261929 
VAZ000-NCZ000-262130-

Mesoscale Discussion 1351
NWS Storm Prediction Center Norman OK
0229 PM CDT Mon Jul 26 2021

Areas affected...South-central and southeastern
Virginia...north-central North Carolina

Concerning...Severe Thunderstorm Watch 392...

Valid 261929Z - 262130Z

The severe weather threat for Severe Thunderstorm Watch 392
continues.

SUMMARY...Damaging winds will remain possibly through early evening.
A cluster of storms near Richmond, VA poses the greatest short-term
threat. Further clustering of storms may occur this afternoon near
the Blue Ridge.

DISCUSSION...Scattered thunderstorms continue to move south and east
off of the Blue Ridge as well as near Richmond, VA. The cluster near
Richmond recently produced a 36 kt gust and has shown increasing
potential for damaging wind gusts on recent KAKQ radar velocity
imagery. This cluster will continue south-southeastward into a
weakly sheared, but moderately unstable, airmass in southeastern
Virginia. Local extensions in area of WW 392 may be needed for this
activity. Storms near the Blue Ridge have shown less organization
over the past couple hours, but still have produced occasional wind
damage reports and marginally severe hail. The potential for,
primarily, damaging wind gusts is expected to continue through early
evening as temperatures continue to warm into the upper 80s F to low
90s F in the region.

..Wendt.. 07/26/2021

...Please see www.spc.noaa.gov for graphic product...

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

LAT...LON   36157824 35617951 35588013 36098073 36768038 37917923
            38027888 38057858 38067771 37717696 37207628 36777634
            36617676 36157824

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 26, 12:58 PM EDTMesoscale DiscussionSPCAlamance, Cabarrus, Caswell, Chatham, Davidson, Davie and 17 more2 hr
Jul 26, 1:39 PM EDTSevere Thunderstorm WatchSPCAlamance, Caswell, Davidson, Forsyth, Guilford, Orange and 4 more6 hr
Jul 26, 5:43 PM EDTMesoscale DiscussionSPCCamden, Chowan, Currituck, Gates, Hertford, Pasquotank and 3 more92 min

Nearby

Mesoscale Discussions in Virginia, 2021Mesoscale Discussions in North Carolina, 2021Every mesoscale discussion in 2021

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.