Alert archive / South Carolina / Mesoscale Discussions in 2021
Mesoscale Discussion 493
The Storm Prediction Center issued this mesoscale discussion at May 3, 2021, 2:42 PM EDT for 5 counties in South Carolina. It was in force for 63 min.
The area
The outline as issued.
The facts
- Issued
- May 3, 2021, 2:42 PM EDT (18:42 UTC)
- Expired
- May 3, 2021, 3:45 PM EDT
- In force
- 63 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 129
Counties Abbeville County, SC, Greenwood County, SC, Laurens County, SC, Newberry County, SC, Union County, SC
The radar
The Greer radar (KGSP), 57 km from the middle of the area, began a volume at 18:47 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, 6.7 hours before the alert went out and 249 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.
- 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
The text
As transmitted.
269
ACUS11 KWNS 031843
SWOMCD
SPC MCD 031842
SCZ000-031945-
Mesoscale Discussion 0493
NWS Storm Prediction Center Norman OK
0142 PM CDT Mon May 03 2021
Areas affected...northern South Carolina
Concerning...Tornado Watch 129...
Valid 031842Z - 031945Z
The severe weather threat for Tornado Watch 129 continues.
SUMMARY...Greatest short-term threat for tornadoes is expected to
remain across northern South Carolina through.
DISCUSSION...A couple of supercells with persistent strong low-level
mesocyclones and history of tornadoes have crossed into western
South Carolina. These storms are moving east near 30 kt along a
stalled boundary. Effective bulk shear around 45 kt remains
favorable for supercells. Tendency has been for near surface winds
to veer to southwesterly with time which has reduced the size of 0-2
km hodographs in the moist warm sector. This suggests greatest
near-term tornado threat will probably remain with storms moving
east and interacting with the boundary where augmented low-level
shear/vorticity resides.
..Dial.. 05/03/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CAE...GSP...
LAT...LON 34378267 34608200 34818150 34498123 34238151 33998234
34378267SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 3, 1:03 PM EDT | Mesoscale Discussion | SPC | Abbeville, Chester, Edgefield, Fairfield, Greenwood, Laurens and 4 more | 87 min |
| May 3, 1:25 PM EDT | Tornado Watch | SPC | Abbeville, Aiken, Bamberg, Barnwell, Calhoun, Chester and 18 more | 6 hr |
| May 3, 4:26 PM EDT | Mesoscale Discussion | SPC | Aiken, Allendale, Bamberg, Barnwell, Calhoun, Clarendon and 11 more | 94 min |
Nearby
Mesoscale Discussions in South 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.