Alert archive / Mississippi / Mesoscale Discussions in 2021
Mesoscale Discussion 1058
The Storm Prediction Center issued this mesoscale discussion at Jun 21, 2021, 7:17 PM CDT for 11 parishes in Louisiana; 23 counties in Mississippi. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Jun 21, 2021, 7:17 PM CDT (00:17 UTC)
- Expired
- Jun 21, 2021, 9:15 PM CDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
All 34 counties
Avoyelles Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, Franklin Parish, LA, Grant Parish, LA, LaSalle Parish, LA, Madison Parish, LA, Rapides Parish, LA, Richland Parish, LA, Tensas Parish, LA, Adams County, MS, Amite County, MS, Attala County, MS, Claiborne County, MS, Copiah County, MS, Franklin County, MS, Hinds County, MS, Holmes County, MS, Jefferson County, MS, Jefferson Davis County, MS, Lawrence County, MS, Leake County, MS, Lincoln County, MS, Madison County, MS, Neshoba County, MS, Newton County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Warren County, MS, Wilkinson County, MS, Yazoo County, MS
The radar
The Jackson/Brandon,MS radar (KDGX), 115 km from the middle of the area, began a volume at 00:19 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, 0.3 hours before the alert went out and 108 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
- 732 J/kg
- Mixed-layer CIN
- -42 J/kg
- Mixed-layer LCL
- 1049 m above ground
- 0-6 km bulk shear
- 22 kt
- 0-1 km storm-relative helicity
- 102 m²/s²
- 0-3 km storm-relative helicity
- 129 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.3
The text
As transmitted.
973
ACUS11 KWNS 220017
SWOMCD
SPC MCD 220017
MSZ000-LAZ000-220215-
Mesoscale Discussion 1058
NWS Storm Prediction Center Norman OK
0717 PM CDT Mon Jun 21 2021
Areas affected...Eastern Louisiana and central to southern
Mississippi
Concerning...Severe potential...Watch unlikely
Valid 220017Z - 220215Z
Probability of Watch Issuance...5 percent
SUMMARY...A line of thunderstorms moving across the lower
Mississippi River Valley may produce sporadic wind damage, but the
overall severe threat will remain low enough to preclude the need
for a watch.
DISCUSSION...Regional radar imagery has revealed a gradually
organizing line from western/central LA into western MS along and
ahead of a southeastward moving cold front. Although GOES IR imagery
shows a few stronger updrafts within the line, no wind damage or
strong wind reports have been noted thus far. However, the line is
moving into a corridor of higher low-level theta-e air and better
instability (upwards of 2000 J/kg MLCAPE), which may support some
intensification in the next 1-2 hours prior to the onset of gradual
boundary layer stabilization due to the loss of daytime heating.
Generally weak deep-layer shear is noted over the region, and a
slightly stronger line-normal component to the mid/upper-level flow
is allowing the LA segment of the line to propagate to the southeast
faster than the MS segment. This section may present a better wind
threat in the near term, though the axis of instability ahead of
this section is rather narrow. Overall, the low probability for a
substantial severe threat and limited spatial extent of the threat
preclude a watch.
..Moore/Grams.. 06/22/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...JAN...LIX...LCH...SHV...
LAT...LON 31299298 31879246 32399205 32719102 33129024 33318967
32968905 32508906 31888938 31309020 30979081 30939166
30979233 31109289 31299298Nearby
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.