Alert archive / Mississippi / Mesoscale Discussions in 2021
Mesoscale Discussion 943
The Storm Prediction Center issued this mesoscale discussion at Jun 13, 2021, 10:45 AM CDT for 16 counties in Alabama; 46 counties in Mississippi. It was in force for 60 min.
The area
The outline as issued.
The facts
- Issued
- Jun 13, 2021, 10:45 AM CDT (15:45 UTC)
- Expired
- Jun 13, 2021, 11:45 AM CDT
- In force
- 60 min
- Issued by
- the Storm Prediction Center
- Concerning
- Outlook upgrade
All 62 counties
Choctaw County, AL, Colbert County, AL, Cullman County, AL, Fayette County, AL, Franklin County, AL, Greene County, AL, Hale County, AL, Lamar County, AL, Lawrence County, AL, Marengo County, AL, Marion County, AL, Pickens County, AL, Sumter County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL, Attala County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Claiborne County, MS, Clarke County, MS, Clay County, MS, Copiah County, MS, Covington County, MS, Grenada County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Itawamba County, MS, Jasper County, MS, Jefferson Davis County, MS, Jones County, MS, Kemper County, MS, Lafayette County, MS, Lauderdale County, MS, Lawrence County, MS, Leake County, MS, Lee 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, Pontotoc County, MS, Prentiss County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Union County, MS, Warren County, MS, Wayne County, MS, Webster County, MS, Winston County, MS, Yalobusha County, MS, Yazoo County, MS
The radar
The Columbus AFB radar (KGWX), 94 km from the middle of the area, began a volume at 15:45 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
Jackson, MS (KJAN), launched 12:00Z, 3.8 hours before the alert went out and 146 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
- 2570 J/kg
- Mixed-layer CIN
- -25 J/kg
- Mixed-layer LCL
- 869 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 44 m²/s²
- 0-3 km storm-relative helicity
- 50 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.5
The text
As transmitted.
500
ACUS11 KWNS 131546
SWOMCD
SPC MCD 131545
ALZ000-MSZ000-LAZ000-131645-
Mesoscale Discussion 0943
NWS Storm Prediction Center Norman OK
1045 AM CDT Sun Jun 13 2021
Areas affected...western AL...much of northern and central MS
Concerning...Outlook upgrade
Valid 131545Z - 131645Z
SUMMARY...A very moist/extremely unstable airmass over MS and
western AL will support strong to severe multicell clusters moving
south-southwest. Water-loaded wet microbursts capable of 50-70 mph
gusts and scattered wind damage are possible. A categorical upgrade
to Slight Risk (cat 2) and an expansion of the Marginal Risk (cat 1)
will be forthcoming in the 1630 UTC convective outlook.
DISCUSSION...Visible satellite imagery shows mostly clear skies with
the early development of cumulus fields over MS and AL. A weak
mid-level vorticity maximum located over the TN Valley is forecast
to slowly move to the south-southwest near the MS/AL border this
afternoon. Late morning surface temperatures have warmed to near 90
deg F with upper 70s deg F dewpoints. Modifying the 7am Jackson, MS
raob for 10am surface conditions (90/75) yields 3700 J/kg MLCAPE and
a lowest 100 mb mean mixing ratio near 18 g/kg. A belt of strong
25-30 kt northerly 500 mb flow was sampled by the 7am Jackson, MS
raob and more recent Jackson and Columbus MS WSR-88D VAD data.
Slightly stronger flow was noted at the Birmingham, AL VAD.
Model guidance shows the development of multicells beginning by
early afternoon over northeast MS and northwest AL. Upscale growth
into a few linear clusters is expected as these clusters move to the
south-southwest during the afternoon and intensify. Steep low-level
lapse rates and the aforementioned moisture will be favorable for
water-loaded downdrafts. It appears the greatest concentration of
50-70 mph gusts will focus over central MS and perhaps into far
west-central AL during the 2-6pm period.
..Smith/Grams.. 06/13/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BMX...HUN...MOB...MEG...JAN...
LAT...LON 34279000 34708866 34778756 34168677 32038765 31448852
31549050 32059117 34279000SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 13, 12:22 PM CDT | Severe Thunderstorm Watch | SPC | Choctaw, Clarke, Fayette, Greene, Hale, Lamar and 9 more | 9 hr |
| Jun 13, 12:51 PM CDT | Mesoscale Discussion | SPC | Mobile | 114 min |
| Jun 13, 1:25 PM CDT | Mesoscale Discussion | SPC | Choctaw, Greene, Marengo, Sumter | 2 hr |
| Jun 13, 3:43 PM CDT | Mesoscale Discussion | SPC | Covington, Jasper, Jones, Leake, Newton, Scott and 1 more | 2 hr |
Nearby
Mesoscale Discussions in Mississippi, 2021Mesoscale Discussions in Alabama, 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.