Alert archive / Alabama / Mesoscale Discussions in 2021

Mesoscale Discussion 350

April 9, 20218 counties in Alabama; 4 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Apr 9, 2021, 5:54 PM CDT for 8 counties in Alabama; 4 counties in Mississippi. It was in force for 96 min.

The area

The outline as issued.

The facts

Issued: Apr 9, 2021, 5:54 PM CDT (22:54 UTC)
Expired: Apr 9, 2021, 7:30 PM CDT
In force: 96 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 77

Counties Fayette County, AL, Greene County, AL, Lamar County, AL, Marion County, AL, Pickens County, AL, Sumter County, AL, Tuscaloosa County, AL, Walker County, AL, Kemper County, MS, Lauderdale County, MS, Lowndes County, MS, Noxubee County, MS

The radar

The Columbus AFB radar (KGWX), 86 km from the middle of the area, began a volume at 22:57 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.

Severe Thunderstorm Watch 85Apr 9, 9:15 PM CDT

The nearest sounding before it

Birmingham, AL (KBMX), launched 12:00Z, 10.9 hours before the alert went out and 117 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: 89 J/kg
Mixed-layer CIN: -208 J/kg
Mixed-layer LCL: 1321 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 70 m²/s²
0-3 km storm-relative helicity: 141 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted.

776 
ACUS11 KWNS 092254
SWOMCD
SPC MCD 092254 
ALZ000-MSZ000-100030-

Mesoscale Discussion 0350
NWS Storm Prediction Center Norman OK
0554 PM CDT Fri Apr 09 2021

Areas affected...central and western Alabama

Concerning...Severe Thunderstorm Watch 77...

Valid 092254Z - 100030Z

The severe weather threat for Severe Thunderstorm Watch 77
continues.

SUMMARY...Storms over west-central Alabama may produce hail or
localized wind damage as they continue north. An additional watch is
not expected in the near term for this activity, but local
extensions may be considered.

DISCUSSION...A cluster of left-moving cells persist over
west-central AL, with other cells developing into east-central MS.
The air mass remains very unstable from this longitude westward,
with sufficient hodograph length to support left movers. Steep lapse
rates aloft will continue to favor hail, with localized strong wind
gusts also possible.

..Jewell.. 04/09/2021

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

ATTN...WFO...BMX...MOB...MEG...JAN...

LAT...LON   33268726 32728773 32478809 32208845 32288894 32628910
            33748851 34158821 34208760 33878727 33268726

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 9, 2:49 AM CDT	Mesoscale Discussion	SPC	Baldwin, Mobile	2 hr
Apr 9, 7:38 AM CDT	Mesoscale Discussion	SPC	Autauga, Barbour, Bullock, Butler, Chambers, Clarke and 17 more	3 hr
Apr 9, 11:44 AM CDT	Mesoscale Discussion	SPC	Autauga, Bibb, Blount, Calhoun, Chambers, Chilton and 28 more	2 hr
Apr 9, 12:54 PM CDT	Severe Thunderstorm Watch	SPC	Autauga, Bibb, Blount, Chilton, Coosa, Dallas and 19 more	7 hr
Apr 9, 1:25 PM CDT	Mesoscale Discussion	SPC	Bolivar, Coahoma, DeSoto, Grenada, Humphreys, Issaquena and 9 more	95 min
Apr 9, 3:10 PM CDT	Mesoscale Discussion	SPC	Bolivar, Carroll, Coahoma, DeSoto, Grenada, Humphreys and 12 more	95 min
Apr 9, 3:42 PM CDT	Severe Thunderstorm Watch	SPC	Alcorn, Attala, Benton, Bolivar, Calhoun, Carroll and 52 more	7 hr
Apr 9, 6:14 PM CDT	Mesoscale Discussion	SPC	Attala, Calhoun, Carroll, Chickasaw, Choctaw, Clay and 23 more	3 hr

Nearby

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