Alert archive / Mississippi / Mesoscale Discussions in 2021

Mesoscale Discussion 33

January 25, 20217 counties in Alabama; 25 counties in Mississippi; 11 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at Jan 25, 2021, 4:49 PM CST for 7 counties in Alabama; 25 counties in Mississippi; 11 counties in Tennessee. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued: Jan 25, 2021, 4:49 PM CST (22:49 UTC)
Expired: Jan 25, 2021, 6:15 PM CST
In force: 86 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch possible
Chance of a watch: 60%

All 43 counties

Colbert County, AL, Franklin County, AL, Lamar County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Marion County, AL, Alcorn County, MS, Attala County, MS, Benton County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Clay County, MS, Grenada County, MS, Holmes County, MS, Itawamba County, MS, Lafayette County, MS, Lee County, MS, Lowndes County, MS, Monroe County, MS, Montgomery County, MS, Oktibbeha County, MS, Pontotoc County, MS, Prentiss County, MS, Tippah County, MS, Tishomingo County, MS, Union County, MS, Webster County, MS, Winston County, MS, Yalobusha County, MS, Chester County, TN, Decatur County, TN, Giles County, TN, Hardeman County, TN, Hardin County, TN, Lawrence County, TN, Lewis County, TN, Maury County, TN, McNairy County, TN, Perry County, TN, Wayne County, TN

The radar

The Columbus AFB radar (KGWX), 44 km from the middle of the area, began a volume at 22:48 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 3Jan 25, 5:50 PM CST

The nearest sounding before it

Little Rock, AR (KLZK), launched 12:00Z, 10.8 hours before the alert went out and 137 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: 4 J/kg
Mixed-layer CIN: -260 J/kg
Mixed-layer LCL: 539 m above ground
0-6 km bulk shear: 68 kt
0-1 km storm-relative helicity: 650 m²/s²
0-3 km storm-relative helicity: 696 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.5

Open this sounding in Storm Lab

The text

As transmitted.

330 
ACUS11 KWNS 252250
SWOMCD
SPC MCD 252249 
ALZ000-TNZ000-MSZ000-260015-

Mesoscale Discussion 0033
NWS Storm Prediction Center Norman OK
0449 PM CST Mon Jan 25 2021

Areas affected...Northern/Central Mississippi...Western/Middle
Tennessee...Northwest Alabama

Concerning...Severe potential...Watch possible 

Valid 252249Z - 260015Z

Probability of Watch Issuance...60 percent

SUMMARY...Scattered strong thunderstorms are expected across the
Mid-South into Middle TN this evening. Some risk for tornadoes may
necessitate a watch in the next couple of hours.

DISCUSSION...Strong mid-level short-wave trough is ejecting across
the central Plains this evening. The more appreciable height falls
will spread across the Mid-MS into the OH Valley region. Along the
southern fringe of this stronger large-scale forcing, robust
convection has recently developed across portions of western TN
where surface dew points have risen into the mid 60s with surface
temperatures in the lower 70s. This activity should spread
east-northeast along a corridor that is destabilizing just south of
a well-defined warm front. Ample shear/buoyancy exist for supercells
(possibly tornadic supercell ongoing over Fayette County TN) and
there is increasing concern/confidence that other organized
longer-lived storms may develop.

Farther south along the Pacific front, showers are gradually
deepening from northwest MS into northeast LA. Some lightning is
noted with the stronger updrafts but activity has struggled to
organize. It's not entirely clear how many organized supercells
can/will develop along this zone, but shear/buoyancy do favor some
tornado threat. Tornado watch may be warranted for this activity in
the next couple of hours.

..Darrow/Thompson.. 01/25/2021

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

ATTN...WFO...OHX...BMX...HUN...MEG...JAN...

LAT...LON   33159055 35478893 35888710 35008651 33568819 32718919
            33159055

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 25, 5:52 PM CST	Tornado Watch	SPC	Bibb, Blount, Calhoun, Cherokee, Cleburne, Colbert and 25 more	7 hr

Nearby

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