Alert archive / Alabama / Mesoscale Discussions in 2021

Mesoscale Discussion 36

January 26, 202112 counties in Alabama; 9 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Jan 26, 2021, 1:58 AM CST for 12 counties in Alabama; 9 counties in Georgia. It was in force for 92 min.

The area

The outline as issued.

The facts

Issued: Jan 26, 2021, 1:58 AM CST (07:58 UTC)
Expired: Jan 26, 2021, 3:30 AM CST
In force: 92 min
Issued by: the Storm Prediction Center
Concerning: Tornado watch 4

All 21 counties

Bibb County, AL, Calhoun County, AL, Chilton County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Hale County, AL, Perry County, AL, Randolph County, AL, Shelby County, AL, Sumter County, AL, Talladega County, AL, Bartow County, GA, Carroll County, GA, Cherokee County, GA, Cobb County, GA, Douglas County, GA, Forsyth County, GA, Haralson County, GA, Paulding County, GA, Polk County, GA

The radar

The Birmingham radar (KBMX), 41 km from the middle of the area, began a volume at 07:58 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

Birmingham, AL (KBMX), launched 00:00Z, 8.0 hours before the alert went out and 42 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 232 J/kg
Mixed-layer CIN: -87 J/kg
Mixed-layer LCL: 913 m above ground
0-6 km bulk shear: 66 kt
0-1 km storm-relative helicity: 371 m²/s²
0-3 km storm-relative helicity: 501 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 1.0

Open this sounding in Storm Lab

The text

As transmitted.

422 
ACUS11 KWNS 260759
SWOMCD
SPC MCD 260758 
GAZ000-ALZ000-260930-

Mesoscale Discussion 0036
NWS Storm Prediction Center Norman OK
0158 AM CST Tue Jan 26 2021

Areas affected...Portions of central AL and
west-central/northwestern GA

Concerning...Tornado Watch 4...

Valid 260758Z - 260930Z

The severe weather threat for Tornado Watch 4 continues.

SUMMARY...An isolated severe threat may persist for a couple more
hours early this morning before gradually diminishing. A couple
tornadoes and occasional strong/gusty winds should be the main
threats.

DISCUSSION...Recent radar imagery shows a broken line of storms
extending northeast to southwest across northwestern GA and central
AL. The low-level flow across this region should have a tendency to
gradually veer to a more southwesterly direction and slowly weaken
as the strongest portion of a low-level jet advances into the
Carolinas over the next few hours. Even so, there should still be
enough veering/strengthening of the wind field in low levels
(reference 06Z BMX sounding) to support updraft rotation. A couple
tornadoes will remain possible in the short term with storms
advancing northeastward within the broken line. Isolated
strong/gusty winds producing occasional damage may also occur with
any cell that can acquire a small bowing structure. Current
expectations are for this isolated severe threat to gradually
diminish later this morning as the low-level flow becomes
increasingly parallel to the ongoing convection, which should reduce
0-1 km SRH. The marginal thermodynamic environment across
west-central into northern GA should also limit the eastward extent
of any meaningful severe risk.

..Gleason.. 01/26/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...FFC...BMX...

LAT...LON   32398833 32668824 33148734 33908569 34248512 34368415
            34158410 33778453 33428499 32818609 32388745 32338795
            32398833

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 25, 9:19 PM CST	Mesoscale Discussion	SPC	Blount, Colbert, Cullman, Fayette, Franklin, Greene and 16 more	116 min
Jan 25, 11:40 PM CST	Mesoscale Discussion	SPC	Bibb, Blount, Calhoun, Cherokee, Clay, Cleburne and 10 more	2 hr
Jan 26, 12:37 AM CST	Tornado Watch	SPC	Bibb, Calhoun, Cherokee, Chilton, Clay, Cleburne and 13 more	4 hr

Nearby

Mesoscale Discussions in Alabama, 2021 Mesoscale Discussions in Georgia, 2021 Every 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.