Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 488
The Storm Prediction Center issued this mesoscale discussion at May 3, 2021, 11:20 AM EDT for 4 counties in Georgia. It was in force for 55 min.
The area
The outline as issued.
The facts
- Issued
- May 3, 2021, 11:20 AM EDT (15:20 UTC)
- Expired
- May 3, 2021, 12:15 PM EDT
- In force
- 55 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 127
Counties Clayton County, GA, DeKalb County, GA, Gwinnett County, GA, Rockdale County, GA
The radar
The Atlanta radar (KFFC), 51 km from the middle of the area, began a volume at 15:18 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 12:00Z, 3.3 hours before the alert went out and 47 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
- 674 J/kg
- Mixed-layer CIN
- -54 J/kg
- Mixed-layer LCL
- 671 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 207 m²/s²
- 0-3 km storm-relative helicity
- 272 m²/s²
- Significant tornado parameter
- 0.8
- Supercell composite
- 4.8
The text
As transmitted.
196 ACUS11 KWNS 031520 SWOMCD SPC MCD 031520 GAZ000-031615- Mesoscale Discussion 0488 NWS Storm Prediction Center Norman OK 1020 AM CDT Mon May 03 2021 Areas affected...north Georgia Concerning...Tornado Watch 127... Valid 031520Z - 031615Z The severe weather threat for Tornado Watch 127 continues. SUMMARY...The tornado threat will remain greatest across north central GA, especially near and east of the Atlanta metro area through 16Z. DISCUSSION...Latest VWP data show low-level shear has strengthened during the past hour with 0-1 km storm relative helicity around 400 m2/s2. Line of storms with embedded cyclic supercells currently moving through the eastern Atlanta metro area will remain in a favorable environment for occasional low-level mesocyclones and tornadoes as it continues east during the next hour as dewpoints continue to rise through the upper 60s F. ..Dial.. 05/03/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FFC... LAT...LON 33728449 34018438 34038383 33628388 33428459 33728449
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 3, 10:04 AM EDT | Mesoscale Discussion | SPC | Barrow, Butts, Carroll, Clayton, Cobb, Coweta and 15 more | 86 min |
| May 3, 10:29 AM EDT | Tornado Watch | SPC | Baldwin, Barrow, Bartow, Bibb, Butts, Carroll and 45 more | 5 hr |
| May 3, 1:03 PM EDT | Mesoscale Discussion | SPC | Barrow, Butts, Clarke, Clayton, Cobb, Columbia and 30 more | 87 min |
| May 3, 1:25 PM EDT | Tornado Watch | SPC | Burke, Columbia, Elbert, Lincoln, McDuffie, Richmond | 6 hr |
| May 3, 3:05 PM EDT | Mesoscale Discussion | SPC | Baldwin, Barrow, Bibb, Butts, Carroll, Chattahoochee and 36 more | 55 min |
| May 3, 3:23 PM EDT | Severe Thunderstorm Watch | SPC | Baldwin, Barrow, Bibb, Butts, Carroll, Chattahoochee and 55 more | 6 hr |
| May 3, 4:26 PM EDT | Mesoscale Discussion | SPC | Richmond | 94 min |
| May 3, 5:00 PM EDT | Mesoscale Discussion | SPC | Baldwin, Bibb, Butts, Calhoun, Carroll, Chattahoochee and 45 more | 90 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.