Alert archive / Georgia / Mesoscale Discussions in 2020
Mesoscale Discussion 39
The Storm Prediction Center issued this mesoscale discussion at Jan 11, 2020, 12:20 PM CST for 15 counties in Alabama; 23 counties in Georgia; 12 counties in Tennessee. It was in force for 85 min.
The area
The outline as issued.
The facts
- Issued
- Jan 11, 2020, 12:20 PM CST (18:20 UTC)
- Expired
- Jan 11, 2020, 1:45 PM CST
- In force
- 85 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 95%
All 50 counties
Blount County, AL, Calhoun County, AL, Chambers County, AL, Cherokee County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, DeKalb County, AL, Etowah County, AL, Jackson County, AL, Marshall County, AL, Randolph County, AL, St. Clair County, AL, Talladega County, AL, Tallapoosa County, AL, Bartow County, GA, Carroll County, GA, Catoosa County, GA, Chattooga County, GA, Cherokee County, GA, Cobb County, GA, Coweta County, GA, Dade County, GA, Douglas County, GA, Fannin County, GA, Floyd County, GA, Fulton County, GA, Gilmer County, GA, Gordon County, GA, Haralson County, GA, Heard County, GA, Murray County, GA, Paulding County, GA, Pickens County, GA, Polk County, GA, Troup County, GA, Walker County, GA, Whitfield County, GA, Bledsoe County, TN, Bradley County, TN, Franklin County, TN, Grundy County, TN, Hamilton County, TN, Marion County, TN, McMinn County, TN, Meigs County, TN, Polk County, TN, Rhea County, TN, Sequatchie County, TN, Van Buren County, TN
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, 6.3 hours before the alert went out and 131 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
- 13 J/kg
- Mixed-layer CIN
- -26 J/kg
- Mixed-layer LCL
- 557 m above ground
- 0-6 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- 417 m²/s²
- 0-3 km storm-relative helicity
- 450 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
175
ACUS11 KWNS 111820
SWOMCD
SPC MCD 111820
NCZ000-GAZ000-TNZ000-ALZ000-111945-
Mesoscale Discussion 0039
NWS Storm Prediction Center Norman OK
1220 PM CST Sat Jan 11 2020
Areas affected...Northeast AL...Northwest GA...Southeast TN
Concerning...Severe potential...Watch likely
Valid 111820Z - 111945Z
Probability of Watch Issuance...95 percent
SUMMARY...Threat for damaging wind and a few tornadoes will increase
this afternoon. Watch issuance is likely by 19Z.
DISCUSSION...An extensive QLCS has recently intensified across
portions of western AL, with at least one confirmed tornado noted
earlier in Pickens County. Gradually increasing downstream
instability (noted in objective mesoanalysis and recent SWIRLL
soundings) will favor maintenance of this system as it moves into
northeast AL and adjacent portions of northwest GA and southern TN.
Very strong wind profiles will also spread eastward with time, with
1 km AGL flow of 60-70 kt and effective SRH expected to increase
into the 450-650 m2/s2 range. This powerful wind field will continue
to support the potential for relatively widespread damaging wind,
and also embedded circulations capable of producing at least brief
tornadoes. New watch issuance is expected by 19Z to cover these
threats from northeast AL into northwest GA and southern TN.
..Dean/Hart.. 01/11/2020
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MRX...FFC...OHX...BMX...HUN...
LAT...LON 35318631 35738554 35708467 35278412 34748407 33928437
32868481 32638544 32668580 32718623 33148651 34108662
34558649 35318631SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jan 11, 6:12 AM CST | Mesoscale Discussion | SPC | Colbert, Lauderdale, Limestone, Madison | 93 min |
| Jan 11, 6:57 AM CST | Tornado Watch | SPC | Colbert, Cullman, Fayette, Franklin, Lamar, Lauderdale and 7 more | 7 hr |
| Jan 11, 7:39 AM CST | Mesoscale Discussion | SPC | Choctaw, Clarke, Greene, Hale, Marengo, Mobile and 3 more | 96 min |
| Jan 11, 7:57 AM CST | Tornado Watch | SPC | Autauga, Baldwin, Bibb, Blount, Butler, Chilton and 22 more | 9 hr |
| Jan 11, 9:28 AM CST | Mesoscale Discussion | SPC | Blount, Cullman, DeKalb, Fayette, Jackson, Lawrence and 7 more | 92 min |
| Jan 11, 9:54 AM CST | Mesoscale Discussion | SPC | Choctaw, Greene, Marengo, Pickens, Sumter, Washington | 96 min |
| Jan 11, 11:50 AM CST | Mesoscale Discussion | SPC | Bibb, Blount, Chilton, Choctaw, Clarke, Cullman and 15 more | 85 min |
| Jan 11, 12:42 PM CST | Tornado Watch | SPC | Barbour, Bullock, Calhoun, Chambers, Cherokee, Clay and 15 more | 7 hr |
| Jan 11, 1:15 PM CST | Mesoscale Discussion | SPC | Blount, Calhoun, Cherokee, Chilton, DeKalb, Etowah and 6 more | 90 min |
| Jan 11, 2:26 PM CST | Mesoscale Discussion | SPC | Barbour, Bullock, Butler, Coffee, Covington, Crenshaw and 10 more | 94 min |
| Jan 11, 2:44 PM CST | Tornado Watch | SPC | Coffee, Dale, Geneva, Henry, Houston | 5 hr |
| Jan 11, 3:16 PM CST | Mesoscale Discussion | SPC | Bullock, Chambers, Clay, Cleburne, Lee, Macon and 3 more | 89 min |
| Jan 11, 5:21 PM CST | Mesoscale Discussion | SPC | Houston | 114 min |
| Jan 11, 3:48 PM CST | Mesoscale Discussion | SPC | Banks, Elbert, Franklin, Habersham, Hart, Madison and 2 more | 117 min |
| Jan 11, 4:38 PM CST | Tornado Watch | SPC | Baldwin, Bleckley, Burke, Clarke, Columbia, Dodge and 34 more | 6 hr |
| Jan 11, 5:36 PM CST | Mesoscale Discussion | SPC | Baldwin, Banks, Barrow, Bibb, Bleckley, Butts and 63 more | 84 min |
| Jan 10, 11:58 PM CST | Tornado Watch | SPC | Crockett, Dyer, Fayette, Gibson, Haywood, Lake and 4 more | 7 hr |
| Jan 11, 3:52 AM CST | Mesoscale Discussion | SPC | Crockett, Dyer, Fayette, Hardeman, Haywood, Lauderdale and 3 more | 83 min |
| Jan 11, 4:17 AM CST | Tornado Watch | SPC | Benton, Carroll, Chester, Decatur, Hardeman, Hardin and 5 more | 6 hr |
| Jan 11, 5:06 AM CST | Mesoscale Discussion | SPC | Fayette, Hardeman, McNairy | 54 min |
| Jan 11, 8:20 AM CST | Mesoscale Discussion | SPC | Bledsoe, Cannon, Clay, Cumberland, DeKalb, Fentress and 11 more | 55 min |
Nearby
Mesoscale Discussions in Georgia, 2020Mesoscale Discussions in Alabama, 2020Mesoscale Discussions in Tennessee, 2020Every mesoscale discussion in 2020
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.