Alert archive / Mississippi / Mesoscale Discussions in 2021

Mesoscale Discussion 306

March 30, 2021Ashley County, Chicot County, Arkansas; East Carroll Parish, Morehouse Parish, West Carroll Parish, Louisiana; 17 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Mar 30, 2021, 9:55 PM CDT for Ashley County, Chicot County, Arkansas; East Carroll Parish, Morehouse Parish, West Carroll Parish, Louisiana; 17 counties in Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Mar 30, 2021, 9:55 PM CDT (02:55 UTC)
Expired: Mar 31, 2021, 12:00 AM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 5%

All 22 counties

Ashley County, AR, Chicot County, AR, East Carroll Parish, LA, Morehouse Parish, LA, West Carroll Parish, LA, Bolivar County, MS, Calhoun County, MS, Carroll County, MS, Grenada County, MS, Humphreys County, MS, Lafayette County, MS, Leflore County, MS, Marshall County, MS, Panola County, MS, Quitman County, MS, Sharkey County, MS, Sunflower County, MS, Tallahatchie County, MS, Tate County, MS, Union County, MS, Washington County, MS, Yalobusha County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 154 km from the middle of the area, began a volume at 02:55 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

Jackson, MS (KJAN), launched 00:00Z, 2.9 hours before the alert went out and 147 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: 844 J/kg
Mixed-layer CIN: -12 J/kg
Mixed-layer LCL: 662 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 187 m²/s²
0-3 km storm-relative helicity: 246 m²/s²
Significant tornado parameter: 1.1
Supercell composite: 5.2

Open this sounding in Storm Lab

The text

As transmitted.

612 
ACUS11 KWNS 310255
SWOMCD
SPC MCD 310255 
MSZ000-ARZ000-LAZ000-310500-

Mesoscale Discussion 0306
NWS Storm Prediction Center Norman OK
0955 PM CDT Tue Mar 30 2021

Areas affected...Northeast Louisiana to Northern Mississippi

Concerning...Severe potential...Watch unlikely 

Valid 310255Z - 310500Z

Probability of Watch Issuance...5 percent

SUMMARY...A few strong storms, with isolated severe, are possible
from northeast Louisiana to northern Mississippi over the next
several hours. Primary threat is gusty winds and perhaps a brief,
weak tornado.

DISCUSSION...Over the last few hours an expanding corridor of
convection has gradually matured into a slow-moving MCS that is
centered over western TN. This activity is shifting east but a
trailing band of scattered strong storms arcs from the body of the
MCS, southwest across northern MS into northeast LA. At times a few
updrafts along the trailing flank have expressed some robustness
with weak supercellular characteristics. 00z soundings from JAN and
SHV exhibited strong surface-6km bulk shear with 0-3km SRH on the
order of 250 M2/S2. Environmental parameters appear adequate for the
maintenance of a few strong storms as this activity spreads
downstream. Even so, aside from gusty winds at times, only a brief
weak tornado appears possible with these pre-frontal storms. Unless
this convection intensifies radar trends do not warrant a severe
thunderstorm watch.

..Darrow/Edwards.. 03/31/2021

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

ATTN...WFO...MEG...JAN...LZK...SHV...

LAT...LON   32959208 34908974 34618871 33408975 32479161 32959208

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 31, 1:55 AM CDT	Mesoscale Discussion	SPC	Calhoun, Chickasaw, Itawamba, Lee, Monroe	2 hr
Mar 31, 10:57 AM CDT	Mesoscale Discussion	SPC	Clarke, Covington, Forrest, Greene, Jasper, Jefferson Davis and 4 more	93 min
Mar 31, 11:19 AM CDT	Severe Thunderstorm Watch	SPC	Clarke, Covington, Forrest, Greene, Jasper, Jefferson Davis and 9 more	6 hr
Mar 31, 2:15 PM CDT	Mesoscale Discussion	SPC	Greene, Perry	90 min

Nearby

Mesoscale Discussions in Mississippi, 2021 Mesoscale Discussions in Louisiana, 2021 Mesoscale Discussions in Arkansas, 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.