Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 1659
The Storm Prediction Center issued this mesoscale discussion at Aug 31, 2021, 7:44 AM CDT for Henry County, Alabama; 48 counties in Georgia. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 31, 2021, 7:44 AM CDT (12:44 UTC)
- Expired
- Aug 31, 2021, 9:45 AM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
All 49 counties
Henry County, AL, Barrow County, GA, Butts County, GA, Calhoun County, GA, Chattahoochee County, GA, Cherokee County, GA, Clay County, GA, Clayton County, GA, Cobb County, GA, Coweta County, GA, Crawford County, GA, Dawson County, GA, DeKalb County, GA, Douglas County, GA, Fannin County, GA, Fayette County, GA, Forsyth County, GA, Fulton County, GA, Gilmer County, GA, Gwinnett County, GA, Hall County, GA, Harris County, GA, Henry County, GA, Jackson County, GA, Jasper County, GA, Lamar County, GA, Lumpkin County, GA, Macon County, GA, Marion County, GA, Meriwether County, GA, Monroe County, GA, Muscogee County, GA, Newton County, GA, Pickens County, GA, Pike County, GA, Quitman County, GA, Randolph County, GA, Rockdale County, GA, Schley County, GA, Spalding County, GA, Stewart County, GA, Sumter County, GA, Talbot County, GA, Taylor County, GA, Terrell County, GA, Upson County, GA, Walton County, GA, Webster County, GA, White County, GA
The radar
The Atlanta radar (KFFC), 19 km from the middle of the area, began a volume at 12:48 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 12:00Z, 0.7 hours before the alert went out and 14 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
- 209 J/kg
- Mixed-layer CIN
- -42 J/kg
- Mixed-layer LCL
- 708 m above ground
- 0-6 km bulk shear
- 25 kt
- 0-1 km storm-relative helicity
- 283 m²/s²
- 0-3 km storm-relative helicity
- 351 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 2.5
The text
As transmitted.
439
ACUS11 KWNS 311244
SWOMCD
SPC MCD 311244
GAZ000-ALZ000-311445-
Mesoscale Discussion 1659
NWS Storm Prediction Center Norman OK
0744 AM CDT Tue Aug 31 2021
Areas affected...Extreme southeast AL into western and northern GA
Concerning...Severe potential...Watch possible
Valid 311244Z - 311445Z
Probability of Watch Issuance...40 percent
SUMMARY...The threat for a couple of tornadoes may increase by
mid-late morning with modest destabilization, and a tornado watch
may need to be considered.
DISCUSSION...The primary confluence band, east of the remnants of
Ida, continues to move eastward from AL into western GA this
morning. Weak rotation has been noted the past few hours with
embedded/weak supercell structure. However, once temperatures warm
into the upper 70s (per the 12z FFC sounding), there will be an
increased in surface-based CAPE and a reduction in near-surface
convective inhibition. Given the continued presence of 250-300
m2/s2 effective SRH along the confluence band, destabilization near
the surface may promote an increase in the threat for a couple of
tornadoes. This area will be monitored closely for any increase in
tornado threat, and the potential for a tornado watch by mid-late
morning.
..Thompson.. 08/31/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GSP...FFC...TAE...BMX...
LAT...LON 33138359 31468439 31368523 31798528 32938493 34118470
34728463 34898436 34778383 34268345 33138359SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 31, 4:31 AM CDT | Mesoscale Discussion | SPC | Bullock, Chambers, Cleburne, Crenshaw, Lee, Macon and 4 more | 89 min |
| Aug 31, 3:49 PM CDT | Mesoscale Discussion | SPC | Geneva, Henry, Houston, Russell | 116 min |
| Aug 31, 6:44 PM CDT | Mesoscale Discussion | SPC | Dale, Geneva, Henry, Houston | 91 min |
| Aug 31, 1:03 PM CDT | Mesoscale Discussion | SPC | Banks, Barrow, Butts, Carroll, Cherokee, Clarke and 47 more | 117 min |
Nearby
Mesoscale Discussions in Georgia, 2021Mesoscale Discussions in Alabama, 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.