Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 270
The Storm Prediction Center issued this mesoscale discussion at Mar 26, 2021, 4:21 AM EDT for 17 counties in Georgia; Abbeville County, South Carolina. It was in force for 54 min.
The area
The outline as issued.
The facts
- Issued
- Mar 26, 2021, 4:21 AM EDT (08:21 UTC)
- Expired
- Mar 26, 2021, 5:15 AM EDT
- In force
- 54 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 56
Counties Barrow County, GA, Clarke County, GA, Clayton County, GA, Coweta County, GA, DeKalb County, GA, Elbert County, GA, Fayette County, GA, Henry County, GA, Madison County, GA, Morgan County, GA, Newton County, GA, Oconee County, GA, Oglethorpe County, GA, Rockdale County, GA, Troup County, GA, Walton County, GA, Wilkes County, GA, Abbeville County, SC
The radar
The Atlanta radar (KFFC), 100 km from the middle of the area, began a volume at 08:21 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
Peachtre/Fal Fld, GA (KFFC), launched 00:00Z, 8.4 hours before the alert went out and 94 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
- 344 J/kg
- Mixed-layer CIN
- -14 J/kg
- Mixed-layer LCL
- 1291 m above ground
- 0-6 km bulk shear
- 76 kt
- 0-1 km storm-relative helicity
- 328 m²/s²
- 0-3 km storm-relative helicity
- 476 m²/s²
- Significant tornado parameter
- 0.6
- Supercell composite
- 6.8
The text
As transmitted.
175
ACUS11 KWNS 260821
SWOMCD
SPC MCD 260821
SCZ000-GAZ000-260915-
Mesoscale Discussion 0270
NWS Storm Prediction Center Norman OK
0321 AM CDT Fri Mar 26 2021
Areas affected...Parts of the Georgia into South Carolina Piedmont
Concerning...Tornado Watch 56...
Valid 260821Z - 260915Z
The severe weather threat for Tornado Watch 56 continues.
SUMMARY...The risk of severe thunderstorms may finally be in the
process of diminishing. If current trends continue, the remaining
valid portion of Tornado Watch 56 may be cancelled early.
DISCUSSION...Latest VWP data supports Rapid Refresh model forecasts
indicating that low-level hodographs are in the process of shrinking
and becoming more linear, along a pre-frontal low-level confluence
zone focused near the 850 mb jet axis. Across the Georgia into
South Carolina Piedmont, speeds along this axis are beginning to
weaken, as the main short wave trough of influence continues into
the Great Lakes region. As this occurs, forcing for ascent along
this zone is also weakening, and convective intensities are
following suit. Severe weather potential across the Greater Atlanta
metro area appears to have diminished, and similar trends are
underway east-northeastward through the remainder of the watch area.
..Kerr.. 03/26/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CAE...GSP...FFC...
LAT...LON 34288303 34258233 33778271 33348411 32978510 33468500
34098370 34288303SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 25, 11:26 PM EDT | Mesoscale Discussion | SPC | Coweta, Fayette, Heard | 64 min |
| Mar 26, 12:34 AM EDT | Mesoscale Discussion | SPC | Barrow, Cherokee, Clarke, Clayton, Cobb, Coweta and 11 more | 56 min |
| Mar 26, 1:55 AM EDT | Tornado Watch | SPC | Banks, Barrow, Butts, Clarke, Clayton, Coweta and 31 more | 3 hr |
| Mar 26, 1:56 PM EDT | Mesoscale Discussion | SPC | Baldwin, Bibb, Bleckley, Bryan, Bulloch, Burke and 44 more | 94 min |
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.