Alert archive / Mississippi / Mesoscale Discussions in 2021
Mesoscale Discussion 351
The Storm Prediction Center issued this mesoscale discussion at Apr 9, 2021, 6:14 PM CDT for 8 parishes in Louisiana; 29 counties in Mississippi. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 9, 2021, 6:14 PM CDT (23:14 UTC)
- Expired
- Apr 9, 2021, 9:15 PM CDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 80
All 37 counties
Caldwell Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Richland Parish, LA, West Carroll Parish, LA, Attala County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Clay County, MS, Grenada County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Lafayette County, MS, Leake County, MS, Leflore County, MS, Madison County, MS, Montgomery County, MS, Oktibbeha County, MS, Pontotoc County, MS, Rankin County, MS, Scott County, MS, Sharkey County, MS, Sunflower County, MS, Tallahatchie County, MS, Warren County, MS, Washington County, MS, Webster County, MS, Winston County, MS, Yalobusha County, MS, Yazoo County, MS
The radar
The Jackson/Brandon,MS radar (KDGX), 106 km from the middle of the area, began a volume at 23:15 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 12:00Z, 11.2 hours before the alert went out and 98 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
- 1659 J/kg
- Mixed-layer CIN
- -54 J/kg
- Mixed-layer LCL
- 787 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 127 m²/s²
- 0-3 km storm-relative helicity
- 150 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 4.4
The text
As transmitted.
157
ACUS11 KWNS 092314
SWOMCD
SPC MCD 092314
MSZ000-LAZ000-ARZ000-100215-
Mesoscale Discussion 0351
NWS Storm Prediction Center Norman OK
0614 PM CDT Fri Apr 09 2021
Areas affected...northeast Louisiana into much of central
Mississippi
Concerning...Severe Thunderstorm Watch 80...
Valid 092314Z - 100215Z
The severe weather threat for Severe Thunderstorm Watch 80
continues.
SUMMARY...The threat for damaging straight-line winds may increase
over the next few hours, from northeast Louisiana into central
Mississippi.
DISCUSSION...A broken line of storms extends from near the AR/MS
border into northeast LA. The most intense of these storms was over
northeast LA, with an east/northeast effective motion.
The air mass ahead of these storms is very unstable, with MLCAPE
over 3000 J/kg. Wind speeds in the lower levels are not particularly
strong, but veering from the surface to 3 km will support updraft
propagation.
Recent radar trends show new cells developing south of the more
organized LA/AR structures, near the outflow boundary. With time,
upscale growth and organization of this cluster may occur as the
system propagates into MS. Damaging winds will be the primary risk,
though sporadic large hail is expected as well due to ample
instability and steep lapse rates aloft.
..Jewell.. 04/09/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MEG...JAN...SHV...
LAT...LON 32618920 32168987 32019090 32029189 32109215 32349228
32699222 32999201 33159133 33419088 33929052 34189026
34418983 34498939 34218880 33458873 32618920SPC 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 | Jefferson, Plaquemines, Saint Bernard | 2 hr |
| Apr 9, 9:49 AM CDT | Mesoscale Discussion | SPC | Bossier, Caddo | 116 min |
| Apr 9, 12:07 PM CDT | Severe Thunderstorm Watch | SPC | Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 5 more | 6 hr |
| Apr 9, 1:25 PM CDT | Mesoscale Discussion | SPC | Bienville, Bossier, Caldwell, Claiborne, De Soto, East Carroll and 12 more | 95 min |
| Apr 9, 3:10 PM CDT | Mesoscale Discussion | SPC | Claiborne, East Carroll, Lincoln, Morehouse, Ouachita, Richland and 2 more | 95 min |
| Apr 9, 3:42 PM CDT | Severe Thunderstorm Watch | SPC | East Carroll, Franklin, Madison, Morehouse, Richland, Tensas and 1 more | 7 hr |
| Apr 9, 5:19 PM CDT | Mesoscale Discussion | SPC | Bienville, Caldwell, Claiborne, De Soto, Franklin, Grant and 10 more | 116 min |
| Apr 9, 5:32 PM CDT | Severe Thunderstorm Watch | SPC | Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more | 7 hr |
| Apr 9, 11:44 AM CDT | Mesoscale Discussion | SPC | Clay, Kemper, Lauderdale, Lowndes, Monroe, Neshoba and 3 more | 2 hr |
| Apr 9, 5:54 PM CDT | Mesoscale Discussion | SPC | Kemper, Lauderdale, Lowndes, Noxubee | 96 min |
Nearby
Mesoscale Discussions in Mississippi, 2021Mesoscale Discussions in Louisiana, 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.