Alert archive / Alabama / Mesoscale Discussions in 2021

Mesoscale Discussion 184

March 16, 202124 counties in Alabama; 11 counties in Georgia; 5 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Mar 16, 2021, 1:07 PM CDT for 24 counties in Alabama; 11 counties in Georgia; 5 counties in Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Mar 16, 2021, 1:07 PM CDT (18:07 UTC)
Expired: Mar 16, 2021, 3:30 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 20%

All 40 counties

Autauga County, AL, Barbour County, AL, Bullock County, AL, Butler County, AL, Choctaw County, AL, Clarke County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Dallas County, AL, Elmore County, AL, Escambia County, AL, Henry County, AL, Houston County, AL, Lowndes County, AL, Macon County, AL, Monroe County, AL, Montgomery County, AL, Pike County, AL, Russell County, AL, Washington County, AL, Wilcox County, AL, Calhoun County, GA, Chattahoochee County, GA, Clay County, GA, Early County, GA, Marion County, GA, Muscogee County, GA, Quitman County, GA, Randolph County, GA, Schley County, GA, Stewart County, GA, Webster County, GA, Forrest County, MS, Greene County, MS, Jones County, MS, Perry County, MS, Wayne County, MS

The radar

The Maxwell AFB radar (KMXX), 155 km from the middle of the area, began a volume at 18:09 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 12:00Z, 6.1 hours before the alert went out and 159 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: 181 J/kg
Mixed-layer CIN: -18 J/kg
Mixed-layer LCL: 623 m above ground
0-6 km bulk shear: 59 kt
0-1 km storm-relative helicity: 194 m²/s²
0-3 km storm-relative helicity: 248 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 1.8

Open this sounding in Storm Lab

The text

As transmitted.

175 
ACUS11 KWNS 161808
SWOMCD
SPC MCD 161807 
GAZ000-ALZ000-MSZ000-162030-

Mesoscale Discussion 0184
NWS Storm Prediction Center Norman OK
0107 PM CDT Tue Mar 16 2021

Areas affected...Southeast MS...Southern AL...Southwest GA

Concerning...Severe potential...Watch unlikely 

Valid 161807Z - 162030Z

Probability of Watch Issuance...20 percent

SUMMARY...A severe storm or two is possible this afternoon from
southeast MS across southern AL and into southwest GA. Damaging wind
gusts and/or a brief tornado are the primary threats.

DISCUSSION...Regional radar imagery has shown sporadic bouts of
updraft intensification over the past hour or so, but little
persistence has been noted thus far. The overall thermodynamic
environment has improved slightly, mainly south of the effective
warm front, which is stretched from MEI eastward/east-northeastward
across central AL into central GA. The better flow aloft still
remains north of this boundary, with the resulting dissociation
between the buoyancy and vertical shear contributing to a generally
marginal environment.

General expectation is for warm-air advection to continue across the
region with shallow cells developing south of the warm front and
moving northward/northeastward. A narrow corridor exists within the
vicinity of the front where buoyancy and vertical shear overlap
enough to support a strong storm or two. Storm mergers could also
lead to brief updraft intensification and the potential for a strong
downdraft.

..Mosier/Grams.. 03/16/2021

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

ATTN...WFO...FFC...TAE...BMX...MOB...JAN...

LAT...LON   31788930 32658630 32458405 31178484 30938930 31788930

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 15, 11:44 PM CDT	Mesoscale Discussion	SPC	Blount, Calhoun, Cherokee, Cullman, DeKalb, Etowah and 16 more	91 min
Mar 16, 2:54 AM CDT	Mesoscale Discussion	SPC	Autauga, Bibb, Blount, Calhoun, Cherokee, Chilton and 31 more	3 hr
Mar 16, 3:48 PM CDT	Mesoscale Discussion	SPC	Attala, Choctaw, Claiborne, Hinds, Holmes, Humphreys and 13 more	117 min

Nearby

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