Alert archive / Mississippi / Mesoscale Discussions in 2021
Mesoscale Discussion 578
The Storm Prediction Center issued this mesoscale discussion at May 9, 2021, 9:32 PM CDT for 8 counties in Alabama; 8 parishes in Louisiana; 34 counties in Mississippi. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- May 9, 2021, 9:32 PM CDT (02:32 UTC)
- Expired
- May 9, 2021, 11:30 PM CDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 161
All 50 counties
Fayette County, AL, Greene County, AL, Lamar County, AL, Marion County, AL, Pickens County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL, Catahoula Parish, LA, Concordia Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Madison Parish, LA, Richland Parish, LA, Tensas Parish, LA, West Carroll Parish, LA, Adams County, MS, Attala County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Claiborne County, MS, Clay County, MS, Copiah County, MS, Grenada County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Kemper County, MS, Leake County, MS, Leflore County, MS, Lowndes County, MS, Madison County, MS, Monroe County, MS, Montgomery County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Oktibbeha County, MS, Rankin County, MS, Scott County, MS, Sharkey County, MS, Warren County, MS, Washington County, MS, Webster County, MS, Winston County, MS, Yazoo County, MS
The radar
The Jackson/Brandon,MS radar (KDGX), 102 km from the middle of the area, began a volume at 02:36 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, 2.5 hours before the alert went out and 100 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
- 632 J/kg
- Mixed-layer CIN
- -123 J/kg
- Mixed-layer LCL
- 935 m above ground
- 0-6 km bulk shear
- 57 kt
- 0-1 km storm-relative helicity
- 212 m²/s²
- 0-3 km storm-relative helicity
- 205 m²/s²
- Significant tornado parameter
- 0.5
- Supercell composite
- 1.1
The text
As transmitted.
131
ACUS11 KWNS 100232
SWOMCD
SPC MCD 100232
ALZ000-MSZ000-LAZ000-ARZ000-100430-
Mesoscale Discussion 0578
NWS Storm Prediction Center Norman OK
0932 PM CDT Sun May 09 2021
Areas affected...Central Mississippi and Northwestern Alabama
Concerning...Severe Thunderstorm Watch 161...
Valid 100232Z - 100430Z
The severe weather threat for Severe Thunderstorm Watch 161
continues.
SUMMARY...The severe threat continues across WW 161. Damaging winds
remain the primary threat, although large hail and perhaps a tornado
or two are possible this evening.
DISCUSSION...Regional radar shows a few organized clusters/lines of
storms within or in proximity to WW 161. In eastern portions of the
watch, a bowing segment with a history of producing wind damage has
been steadily losing intensity as it progresses southeastward into
northwest Alabama and northeast/east-central Mississippi. This line
of storms is encountering an environment worked over by earlier
convection, and thus less favorable thermodynamic conditions (MUCAPE
< 1000 J/kg) exist to support organized convection. Still, a few
damaging wind gusts remain possible with this activity or any storms
that redevelop in this region in the next few hours.
Farther west, a couple clusters of storms with transient embedded
supercell characteristics are entering WW 161. The environment ahead
of these storms will continue to support organized convection,
characterized by 1000-1500 J/kg of MUCAPE and 35-45 kt of effective
bulk shear per SPC Mesoanalysis. The 00z JAN sounding still shows
near 7-8 C/km mid-level lapse rates, with decent low-level shear
(e.g., 20 kt 0-1 km shear; near 200 m^2/s^2 0-1 km SRH) and affirms
the aforementioned kinematic/thermodynamic indices. Damaging winds
will be the primary threat for threat with this activity, although
large hail and perhaps a tornado or two are possible for the
remainder of the evening.
..Karstens.. 05/10/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BMX...HUN...MEG...JAN...SHV...
LAT...LON 33049146 33619035 34088950 34038834 34258759 34428721
34178688 33158715 32568853 31309177 31459196 32379187
32829169 33049146SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 9, 7:29 PM CDT | Severe Thunderstorm Watch | SPC | Fayette, Franklin, Lamar, Marion, Pickens, Tuscaloosa and 2 more | 4 hr |
| May 10, 5:22 PM CDT | Mesoscale Discussion | SPC | Caldwell, Catahoula, Concordia, Franklin, Grant, Jackson and 3 more | 2 hr |
Nearby
Mesoscale Discussions in Mississippi, 2021Mesoscale Discussions in Alabama, 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.