Alert archive / South Carolina / Mesoscale Discussions in 2021

Mesoscale Discussion 499

May 3, 2021Richmond County, Georgia; 17 counties in South Carolina

The Storm Prediction Center issued this mesoscale discussion at May 3, 2021, 4:26 PM EDT for Richmond County, Georgia; 17 counties in South Carolina. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued: May 3, 2021, 4:26 PM EDT (20:26 UTC)
Expired: May 3, 2021, 6:00 PM EDT
In force: 94 min
Issued by: the Storm Prediction Center
Concerning: Tornado watch 129

Counties Richmond County, GA, Aiken County, SC, Allendale County, SC, Bamberg County, SC, Barnwell County, SC, Calhoun County, SC, Clarendon County, SC, Darlington County, SC, Dorchester County, SC, Edgefield County, SC, Florence County, SC, Lee County, SC, Lexington County, SC, Orangeburg County, SC, Richland County, SC, Saluda County, SC, Sumter County, SC, Williamsburg County, SC

The radar

The Columbia radar (KCAE), 50 km from the middle of the area, began a volume at 20:25 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

Charleston AFB, SC (KCHS), launched 12:00Z, 8.4 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: 1333 J/kg
Mixed-layer CIN: -30 J/kg
Mixed-layer LCL: 765 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 128 m²/s²
0-3 km storm-relative helicity: 141 m²/s²
Significant tornado parameter: 0.9
Supercell composite: 5.0

Open this sounding in Storm Lab

The text

As transmitted.

103 
ACUS11 KWNS 032026
SWOMCD
SPC MCD 032026 
SCZ000-GAZ000-032200-

Mesoscale Discussion 0499
NWS Storm Prediction Center Norman OK
0326 PM CDT Mon May 03 2021

Areas affected...Central and southern South Carolina

Concerning...Tornado Watch 129...

Valid 032026Z - 032200Z

The severe weather threat for Tornado Watch 129 continues.

SUMMARY...Primary severe threat including potential for damaging
wind, large hail and a couple of tornadoes will persist across
central SC next couple hours. Threat may spread into western part of
Wilmington NC county warning area after 21Z and eventually into WFO
CHS by early evening.

DISCUSSION...Cluster of storms with embedded supercells and bowing
segments are developing east and southeast through the moderately
unstable warm sector across central SC. Low-level winds have veered
to southwest which is limiting 0-1 km hodograph size, but effective
shear from 40-45 kt remains supportive of occasional supercell
structures. It appears as though the primary threat has transitioned
to isolated damaging wind and large hail, but a tornado or two
remains possible.

..Dial.. 05/03/2021

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

ATTN...WFO...ILM...CHS...CAE...

LAT...LON   33837948 33038030 32908195 33748221 34138172 34477951
            33837948

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 3, 10:04 AM EDT	Mesoscale Discussion	SPC	Barrow, Butts, Carroll, Clayton, Cobb, Coweta and 15 more	86 min
May 3, 10:29 AM EDT	Tornado Watch	SPC	Baldwin, Barrow, Bartow, Bibb, Butts, Carroll and 45 more	5 hr
May 3, 11:20 AM EDT	Mesoscale Discussion	SPC	Clayton, DeKalb, Gwinnett, Rockdale	55 min
May 3, 1:03 PM EDT	Mesoscale Discussion	SPC	Barrow, Butts, Clarke, Clayton, Cobb, Columbia and 30 more	87 min
May 3, 1:25 PM EDT	Tornado Watch	SPC	Burke, Columbia, Elbert, Lincoln, McDuffie, Richmond	6 hr
May 3, 3:05 PM EDT	Mesoscale Discussion	SPC	Baldwin, Barrow, Bibb, Butts, Carroll, Chattahoochee and 36 more	55 min
May 3, 3:23 PM EDT	Severe Thunderstorm Watch	SPC	Baldwin, Barrow, Bibb, Butts, Carroll, Chattahoochee and 55 more	6 hr
May 3, 5:00 PM EDT	Mesoscale Discussion	SPC	Baldwin, Bibb, Butts, Calhoun, Carroll, Chattahoochee and 45 more	90 min
May 3, 2:42 PM EDT	Mesoscale Discussion	SPC	Abbeville, Greenwood, Laurens, Newberry, Union	63 min

Nearby

Mesoscale Discussions in South Carolina, 2021 Mesoscale Discussions in Georgia, 2021 Every 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.