Alert archive / Georgia / Mesoscale Discussions in 2021
Mesoscale Discussion 538
The Storm Prediction Center issued this mesoscale discussion at May 4, 2021, 5:20 PM CDT for 13 counties in Alabama; 11 counties in Florida; 40 counties in Georgia. It was in force for 85 min.
The area
The outline as issued.
The facts
- Issued
- May 4, 2021, 5:20 PM CDT (22:20 UTC)
- Expired
- May 4, 2021, 6:45 PM CDT
- In force
- 85 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...severe thunderstorm watch likely
- Chance of a watch
- 80%
All 64 counties
Barbour County, AL, Bullock County, AL, Chambers County, AL, Coffee County, AL, Covington County, AL, Dale County, AL, Geneva County, AL, Henry County, AL, Houston County, AL, Lee County, AL, Macon County, AL, Pike County, AL, Russell County, AL, Bay County, FL, Calhoun County, FL, Gadsden County, FL, Gulf County, FL, Holmes County, FL, Jackson County, FL, Leon County, FL, Liberty County, FL, Okaloosa County, FL, Walton County, FL, Washington County, FL, Baker County, GA, Bibb County, GA, Calhoun County, GA, Chattahoochee County, GA, Clay County, GA, Colquitt County, GA, Crawford County, GA, Crisp County, GA, Decatur County, GA, Dooly County, GA, Dougherty County, GA, Early County, GA, Grady County, GA, Harris County, GA, Houston County, GA, Jones County, GA, Lee County, GA, Macon County, GA, Marion County, GA, Miller County, GA, Mitchell County, GA, Muscogee County, GA, Peach County, GA, Pulaski County, GA, Quitman County, GA, Randolph County, GA, Schley County, GA, Seminole County, GA, Stewart County, GA, Sumter County, GA, Talbot County, GA, Taylor County, GA, Terrell County, GA, Thomas County, GA, Tift County, GA, Turner County, GA, Upson County, GA, Webster County, GA, Wilcox County, GA, Worth County, GA
The radar
The Ft Rucker radar (KEOX), 44 km from the middle of the area, began a volume at 22:22 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
Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 10.3 hours before the alert went out and 120 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
- 565 J/kg
- Mixed-layer CIN
- -42 J/kg
- Mixed-layer LCL
- 767 m above ground
- 0-6 km bulk shear
- 28 kt
- 0-1 km storm-relative helicity
- 88 m²/s²
- 0-3 km storm-relative helicity
- 105 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 3.5
The text
As transmitted.
039
ACUS11 KWNS 042220
SWOMCD
SPC MCD 042220
GAZ000-FLZ000-ALZ000-042345-
Mesoscale Discussion 0538
NWS Storm Prediction Center Norman OK
0520 PM CDT Tue May 04 2021
Areas affected...Portions of the FL Panhandle...southeastern
AL...and southern/western GA
Concerning...Severe potential...Severe Thunderstorm Watch likely
Valid 042220Z - 042345Z
Probability of Watch Issuance...80 percent
SUMMARY...A severe/damaging wind threat is expected to continue into
the evening with a line of storms moving eastward. Severe
Thunderstorm Watch issuance is likely.
DISCUSSION...An organized QLCS will move eastward across parts of
southern/central AL through the remainder of the afternoon and into
the early evening. A moist and unstable airmass exists downstream of
this convection, and to the south of an outflow boundary where
additional, non-severe storms have formed. As large-scale ascent and
35-40 kt of mid-level flow associated with an upper trough now over
the lower MS Valley continues to overspread AL/GA and the FL
Panhandle, the QLCS should maintain its intensity through much of
the evening. Given the linear nature of this ongoing convection and
steep low-level lapse rates owing to diurnal heating, scattered
damaging downdraft winds should be the main threat. The low-level
flow is not overly strong, and appears mostly veered to
southwesterly per recent surface observations and area VWPs.
Accordingly, any tornado threat should remain rather brief/isolated.
Severe Thunderstorm Watch issuance will likely be needed to address
the damaging wind threat.
..Gleason/Thompson.. 05/04/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FFC...TAE...BMX...MOB...
LAT...LON 30378670 31338653 32988548 32888485 32968399 33078352
31898328 31148356 30578404 30048475 29828535 30078572
30298620 30378670SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 3, 7:13 PM CDT | Mesoscale Discussion | SPC | Autauga, Bullock, Chambers, Coosa, Elmore, Lee and 4 more | 62 min |
| May 4, 5:13 AM CDT | Severe Thunderstorm Watch | SPC | Jackson, Lauderdale, Limestone, Madison | 5 hr |
| May 4, 7:31 AM CDT | Mesoscale Discussion | SPC | Jackson, Lauderdale, Limestone, Madison | 89 min |
| May 4, 8:33 AM CDT | Mesoscale Discussion | SPC | Choctaw, Clarke, Dallas, Greene, Hale, Marengo and 4 more | 117 min |
| May 4, 9:03 AM CDT | Mesoscale Discussion | SPC | Blount, Calhoun, Cherokee, Clay, Cleburne, Cullman and 20 more | 117 min |
| May 4, 9:18 AM CDT | Tornado Watch | SPC | Autauga, Bibb, Blount, Calhoun, Cherokee, Chilton and 28 more | 7 hr |
| May 4, 2:17 PM CDT | Mesoscale Discussion | SPC | Choctaw, Greene, Marengo, Sumter | 88 min |
| May 4, 3:03 PM CDT | Mesoscale Discussion | SPC | Bibb, Blount, Calhoun, Cherokee, Chilton, Clay and 19 more | 117 min |
| May 4, 3:31 PM CDT | Tornado Watch | SPC | Autauga, Baldwin, Bibb, Butler, Chilton, Choctaw and 20 more | 6 hr |
| May 4, 4:46 PM CDT | Mesoscale Discussion | SPC | Autauga, Baldwin, Bibb, Butler, Chilton, Choctaw and 20 more | 89 min |
| May 4, 6:10 PM CDT | Mesoscale Discussion | SPC | Autauga, Coosa, Elmore, Lowndes, Macon, Montgomery and 1 more | 65 min |
| May 4, 6:26 PM CDT | Severe Thunderstorm Watch | SPC | Barbour, Bullock, Chambers, Coffee, Covington, Crenshaw and 8 more | 6 hr |
| May 4, 9:48 AM CDT | Severe Thunderstorm Watch | SPC | Banks, Barrow, Bartow, Butts, Carroll, Catoosa and 43 more | 6 hr |
| May 4, 12:21 PM CDT | Mesoscale Discussion | SPC | Banks, Barrow, Bartow, Carroll, Cherokee, Clarke and 34 more | 114 min |
| May 4, 2:07 PM CDT | Mesoscale Discussion | SPC | Banks, Barrow, Bartow, Butts, Carroll, Cherokee and 35 more | 113 min |
| May 4, 3:56 PM CDT | Severe Thunderstorm Watch | SPC | Burke, Columbia, McDuffie, Richmond | 3 hr |
Nearby
Mesoscale Discussions in Georgia, 2021Mesoscale Discussions in Alabama, 2021Mesoscale Discussions in Florida, 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.