Alert archive / Alabama / Mesoscale Discussions in 2021

Mesoscale Discussion 35

January 25, 202116 counties in Alabama; Haralson County, Polk County, Georgia; 7 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Jan 25, 2021, 11:40 PM CST for 16 counties in Alabama; Haralson County, Polk County, Georgia; 7 counties in Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jan 25, 2021, 11:40 PM CST (05:40 UTC)
Expired: Jan 26, 2021, 1:45 AM CST
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Tornado watch 3

All 25 counties

Bibb County, AL, Blount County, AL, Calhoun County, AL, Cherokee County, AL, Clay County, AL, Cleburne County, AL, Greene County, AL, Hale County, AL, Jefferson County, AL, Pickens County, AL, Shelby County, AL, St. Clair County, AL, Sumter County, AL, Talladega County, AL, Tuscaloosa County, AL, Walker County, AL, Haralson County, GA, Polk County, GA, Kemper County, MS, Lauderdale County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Rankin County, MS, Scott County, MS

The radar

The Birmingham radar (KBMX), 100 km from the middle of the area, began a volume at 05:43 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.

Tornado Watch 4Jan 26, 12:40 AM CST

The nearest sounding before it

Birmingham, AL (KBMX), launched 00:00Z, 5.7 hours before the alert went out and 99 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.

236 
ACUS11 KWNS 260541
SWOMCD
SPC MCD 260540 
GAZ000-ALZ000-MSZ000-260745-

Mesoscale Discussion 0035
NWS Storm Prediction Center Norman OK
1140 PM CST Mon Jan 25 2021

Areas affected...Central Mississippi...North-Central
Alabama...Extreme Northwest Georgia

Concerning...Tornado Watch 3...

Valid 260540Z - 260745Z

The severe weather threat for Tornado Watch 3 continues.

SUMMARY...Severe threat will focus along a corridor from central MS
to extreme northwest GA over the next few hours. The primary risk
will be locally damaging winds along with the threat for a tornado
or two.

DISCUSSION...While large-scale forcing is focused well north of the
central Gulf States, latest satellite imagery suggests deep
convection has intensified over the last hour or so. Cloud-top
evacuation has increased along with lightning flash rates,
indicative of strengthening updrafts. It's not entirely clear why
this activity has increased, but current trends suggest the greatest
focus for the next few hours will concentrate from central MS,
northeast into northwest GA. Supercells will continue to be a
threat, and at times a few of these may exhibit tornadic signatures.
One particular tornadic supercell that passed just north of BHM has
translated into St. Clair County where it has weakened a bit. This
type of updraft/meso cycling can be expected along the
aforementioned corridor for at least the next few hours.

..Darrow.. 01/26/2021

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

ATTN...WFO...FFC...BMX...HUN...JAN...

LAT...LON   32119019 33018887 33968719 34118521 33448508 33078663
            32138923 32119019

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 26, 12:37 AM CST	Tornado Watch	SPC	Bibb, Calhoun, Cherokee, Chilton, Clay, Cleburne and 13 more	4 hr
Jan 26, 1:58 AM CST	Mesoscale Discussion	SPC	Bibb, Calhoun, Chilton, Clay, Cleburne, Coosa and 6 more	92 min

Nearby

Mesoscale Discussions in Alabama, 2021 Mesoscale Discussions in Mississippi, 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.