Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 1191
The Storm Prediction Center issued this mesoscale discussion at Jul 7, 2021, 10:00 PM EDT for 4 counties in Georgia; Beaufort County, Hampton County, Jasper County, South Carolina. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 7, 2021, 10:00 PM EDT (02:00 UTC)
- Expired
- Jul 8, 2021, 12:00 AM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 347
Counties Bryan County, GA, Chatham County, GA, Effingham County, GA, Liberty County, GA, Beaufort County, SC, Hampton County, SC, Jasper County, SC
The radar
The Charleston,SC radar (KCLX), 100 km from the middle of the area, began a volume at 02:01 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
Jacksonville, FL (KJAX), launched 00:00Z, 2.0 hours before the alert went out and 156 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
- 1099 J/kg
- Mixed-layer CIN
- -1 J/kg
- Mixed-layer LCL
- 507 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km storm-relative helicity
- 153 m²/s²
- 0-3 km storm-relative helicity
- 253 m²/s²
- Significant tornado parameter
- 0.8
- Supercell composite
- 4.6
The text
As transmitted.
313
ACUS11 KWNS 080200
SWOMCD
SPC MCD 080200
SCZ000-GAZ000-080400-
Mesoscale Discussion 1191
NWS Storm Prediction Center Norman OK
0900 PM CDT Wed Jul 07 2021
Areas affected...Coastal areas of southeast Georgia and southern
South Carolina
Concerning...Tornado Watch 347...
Valid 080200Z - 080400Z
The severe weather threat for Tornado Watch 347 continues.
SUMMARY...The tornado threat will persist across remaining areas of
WW 347. The greatest near term risk (over the next 1-2 hours) will
reside across coastal areas of the GA/SC border.
DISCUSSION...The primary rain band associated with Tropical Storm
Elsa continues to translate along the GA coast, and periodic
lightning jumps indicate that the thermodynamic environment is still
favorable for strong updrafts despite the loss of diurnal heating.
Velocity data from KJAX shows transient couplets within this band -
namely just offshore. Low-level confluence remains maximized along
the band axis, and high theta-e air in proximity to the coast
(denoted by mid 70s dewpoints) coupled with easterly surface winds
on the northern side of the band are maintaining an environment with
sufficient instability and low-level helicity conducive for brief
tornadoes. The near-term tornado threat will likely be maximized
along this band, which should continue to move along the GA/SC coast
over the next 1-2 hours.
..Moore.. 07/08/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CHS...
LAT...LON 31048123 31518121 31758151 32258160 32548133 32788115
32798068 32578044 32218031 31778041 31338056 30998075
30898099 30908113 31048123SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 8, 1:38 AM EDT | Mesoscale Discussion | SPC | Beaufort, Berkeley, Charleston, Colleton, Dillon, Dorchester and 5 more | 2 hr |
| Jul 8, 2:01 AM EDT | Tornado Watch | SPC | Florence, Georgetown, Horry, Marion, Williamsburg | 7 hr |
| Jul 8, 5:25 AM EDT | Mesoscale Discussion | SPC | Berkeley, Dillon, Florence, Georgetown, Horry, Marion and 1 more | 2 hr |
| Jul 8, 7:09 AM EDT | Mesoscale Discussion | SPC | Georgetown, Horry, Marion | 2 hr |
Nearby
Mesoscale Discussions in Georgia, 2021Mesoscale 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.