Alert archive / Mississippi / Mesoscale Discussions in 2021
Mesoscale Discussion 525
The Storm Prediction Center issued this mesoscale discussion at May 4, 2021, 11:58 AM CDT for Crittenden County, Lee County, Phillips County, Arkansas; 19 counties in Mississippi; 4 counties in Tennessee. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 4, 2021, 11:58 AM CDT (16:58 UTC)
- Expired
- May 4, 2021, 2:00 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
All 26 counties
Crittenden County, AR, Lee County, AR, Phillips County, AR, Alcorn County, MS, Benton County, MS, Calhoun County, MS, Chickasaw County, MS, Coahoma County, MS, DeSoto County, MS, Lafayette County, MS, Lee County, MS, Marshall County, MS, Panola County, MS, Pontotoc County, MS, Prentiss County, MS, Quitman County, MS, Tallahatchie County, MS, Tate County, MS, Tippah County, MS, Tunica County, MS, Union County, MS, Yalobusha County, MS, Fayette County, TN, Hardeman County, TN, McNairy County, TN, Shelby County, TN
The radar
The Memphis radar (KNQA), 71 km from the middle of the area, began a volume at 16:58 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.
The nearest sounding before it
Little Rock, AR (KLZK), launched 12:00Z, 5.0 hours before the alert went out and 14 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.
- Mixed-layer CAPE
- 10 J/kg
- Mixed-layer CIN
- -373 J/kg
- Mixed-layer LCL
- 1101 m above ground
- 0-6 km bulk shear
- 52 kt
- 0-1 km storm-relative helicity
- 62 m²/s²
- 0-3 km storm-relative helicity
- 100 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
311
ACUS11 KWNS 041659
SWOMCD
SPC MCD 041658
TNZ000-MSZ000-ARZ000-041900-
Mesoscale Discussion 0525
NWS Storm Prediction Center Norman OK
1158 AM CDT Tue May 04 2021
Areas affected...Northern MS...Southwest TN
Concerning...Severe potential...Watch possible
Valid 041658Z - 041900Z
Probability of Watch Issuance...60 percent
SUMMARY...Severe thunderstorms capable of large hail and strong wind
gusts are possible this afternoon as a cluster of storms moves into
the region this afternoon.
DISCUSSION...Portions of the Mid-South continue to destabilization
quickly amid diurnal heating and strong low-level moisture
advection. Current mesoanalysis estimates only limited convective
inhibition remains and MLCAPE over 2000 J/kg over northern MS and
adjacent far east-central AR. This region lies downstream of an
ongoing storm cluster across northern LA/southern AR. Expectation is
for portions of this cluster to continue northeastward into the
destabilized air mass over the Mid-South. Steep mid-level lapse
rates and strong deep-layer vertical shear will promote the develop
of strong updrafts capable of large hail and strong downburst winds.
There is some uncertainty how far north the better low-level
moisture will advect before the storm cluster arrives, but the
potential exists for the severe thunderstorm threat to extend into
portions of southwest TN.
..Mosier/Grams.. 05/04/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MEG...JAN...LZK...
LAT...LON 34609110 35309045 35578926 35298816 33928883 33659067
34609110SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 3, 8:38 PM CDT | Mesoscale Discussion | SPC | Arkansas, Baxter, Boone, Calhoun, Carroll, Clark and 60 more | 2 hr |
| May 3, 9:10 PM CDT | Severe Thunderstorm Watch | SPC | Baxter, Benton, Boone, Calhoun, Carroll, Clark and 50 more | 7 hr |
| May 3, 10:22 PM CDT | Mesoscale Discussion | SPC | Boone, Crawford, Franklin, Johnson, Madison, Marion and 2 more | 83 min |
| May 3, 11:34 PM CDT | Mesoscale Discussion | SPC | Baxter, Boone, Carroll, Clark, Cleburne, Conway and 27 more | 86 min |
| May 4, 1:06 AM CDT | Mesoscale Discussion | SPC | Clay, Craighead, Crittenden, Cross, Greene, Jackson and 5 more | 114 min |
| May 4, 1:41 AM CDT | Severe Thunderstorm Watch | SPC | Clay, Craighead, Crittenden, Cross, Greene, Mississippi and 2 more | 6 hr |
| May 4, 2:02 AM CDT | Mesoscale Discussion | SPC | Clay, Conway, Craighead, Cross, Faulkner, Garland and 16 more | 88 min |
| May 4, 4:17 AM CDT | Mesoscale Discussion | SPC | Crittenden | 88 min |
| May 4, 6:44 AM CDT | Mesoscale Discussion | SPC | Bradley, Calhoun, Clark, Cleveland, Columbia, Dallas and 8 more | 2 hr |
| May 4, 10:52 AM CDT | Tornado Watch | SPC | Ashley, Bradley, Calhoun, Chicot, Columbia, Desha and 2 more | 7 hr |
| May 4, 12:18 PM CDT | Severe Thunderstorm Watch | SPC | Phillips | 5 hr |
| May 4, 1:59 PM CDT | Mesoscale Discussion | SPC | Cleburne, Conway, Craighead, Cross, Faulkner, Greene and 17 more | 2 hr |
| May 4, 8:33 AM CDT | Mesoscale Discussion | SPC | Adams, Amite, Claiborne, Clarke, Copiah, Covington and 31 more | 117 min |
| May 4, 9:03 AM CDT | Mesoscale Discussion | SPC | Clay, Lowndes, Monroe, Oktibbeha | 117 min |
| May 4, 9:18 AM CDT | Tornado Watch | SPC | Attala, Carroll, Choctaw, Clarke, Clay, Copiah and 26 more | 7 hr |
| May 4, 12:16 PM CDT | Mesoscale Discussion | SPC | Adams, Claiborne, Copiah, Franklin, Hinds, Issaquena and 4 more | 89 min |
| May 4, 2:17 PM CDT | Mesoscale Discussion | SPC | Attala, Choctaw, Claiborne, Clarke, Copiah, Covington and 26 more | 88 min |
| May 4, 3:03 PM CDT | Mesoscale Discussion | SPC | Chickasaw, Choctaw, Clay, Itawamba, Kemper, Lowndes and 5 more | 117 min |
| May 4, 3:31 PM CDT | Tornado Watch | SPC | Clarke, Covington, Forrest, George, Greene, Hancock and 22 more | 6 hr |
| May 4, 4:46 PM CDT | Mesoscale Discussion | SPC | Clarke, Forrest, George, Greene, Hancock, Harrison and 9 more | 89 min |
| May 4, 1:17 AM CDT | Mesoscale Discussion | SPC | Clay, Cumberland, Fentress, Jackson, Macon, Overton and 3 more | 118 min |
| May 4, 5:13 AM CDT | Severe Thunderstorm Watch | SPC | Bedford, Bledsoe, Cannon, Cheatham, Clay, Coffee and 32 more | 5 hr |
| May 4, 7:31 AM CDT | Mesoscale Discussion | SPC | Anderson, Bedford, Bledsoe, Bradley, Campbell, Cannon and 33 more | 89 min |
| May 4, 8:37 AM CDT | Severe Thunderstorm Watch | SPC | Anderson, Blount, Bradley, Jefferson, Knox, Loudon and 7 more | 3 hr |
Nearby
Mesoscale Discussions in Mississippi, 2021Mesoscale Discussions in Tennessee, 2021Mesoscale Discussions in Arkansas, 2021Every 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.