Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 269
The Storm Prediction Center issued this mesoscale discussion at Mar 26, 2021, 12:34 AM EDT for 17 counties in Georgia. It was in force for 56 min.
The area
The outline as issued.
The facts
- Issued
- Mar 26, 2021, 12:34 AM EDT (04:34 UTC)
- Expired
- Mar 26, 2021, 1:30 AM EDT
- In force
- 56 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 52
Counties Barrow County, GA, Cherokee County, GA, Clarke County, GA, Clayton County, GA, Cobb County, GA, Coweta County, GA, DeKalb County, GA, Fayette County, GA, Forsyth County, GA, Fulton County, GA, Gwinnett County, GA, Henry County, GA, Jackson County, GA, Madison County, GA, Newton County, GA, Rockdale County, GA, Walton County, GA
The radar
The Atlanta radar (KFFC), 47 km from the middle of the area, began a volume at 04:35 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Peachtre/Fal Fld, GA (KFFC), launched 00:00Z, 4.6 hours before the alert went out and 43 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.
933 ACUS11 KWNS 260435 SWOMCD SPC MCD 260434 GAZ000-260530- Mesoscale Discussion 0269 NWS Storm Prediction Center Norman OK 1134 PM CDT Thu Mar 25 2021 Areas affected...northern GA including the Atlanta metro Concerning...Tornado Watch 52... Valid 260434Z - 260530Z The severe weather threat for Tornado Watch 52 continues. SUMMARY...Tornado potential will continue to focus in the southern suburbs of Atlanta through 130am EDT. A watch extension-in-time (EXT) or an additional tornado watch will need to be considered before tornado watch #52 expiration time at 2am EDT. DISCUSSION...Surface observations have indicated over the past 1-2 hours a slow but steady rise in dewpoints to around 66 deg F near Atlanta and areas south and east. More marginal low-level moisture is indicated farther north in northern GA where surface conditions are slightly cooler and drier with dewpoints in the lower 60s. The slightly warmer/richer low-level moisture appears to be a delimiting factor for increased severe potential---namely tornado risk late this evening. KFFC VAD continues to show an impressive low-level wind profile with a large hodograph (500 m2/s2 0-1 km SRH) coupled with over 1000 J/kg MLCAPE according to model forecast soundings. The tornado risk may continue to the eastern bound of the tornado watch #52 towards 2 am EDT. Depending on convective trends, a decision for an additional shorter-than-typical tornado watch or extension in time for the existing watch may become necessary. ..Smith.. 03/26/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FFC... LAT...LON 33368486 34428453 34158309 33298408 33368486
SPC 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, 1:55 AM EDT | Tornado Watch | SPC | Banks, Barrow, Butts, Clarke, Clayton, Coweta and 31 more | 3 hr |
| Mar 26, 4:21 AM EDT | Mesoscale Discussion | SPC | Barrow, Clarke, Clayton, Coweta, DeKalb, Elbert and 11 more | 54 min |
| 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, 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.