Alert archive / Mississippi / Mesoscale Discussions in 2021
Mesoscale Discussion 2016
The Storm Prediction Center issued this mesoscale discussion at Dec 11, 2021, 3:15 AM CST for 4 counties in Alabama; 27 counties in Mississippi. It was in force for 90 min.
The area
The outline as issued.
The facts
- Issued
- Dec 11, 2021, 3:15 AM CST (09:15 UTC)
- Expired
- Dec 11, 2021, 4:45 AM CST
- In force
- 90 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 558
All 31 counties
Colbert County, AL, Franklin County, AL, Lauderdale County, AL, Marion County, AL, Alcorn County, MS, Benton County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Clay County, MS, Grenada County, MS, Holmes County, MS, Humphreys County, MS, Itawamba County, MS, Lafayette County, MS, Lee County, MS, Leflore County, MS, Monroe County, MS, Montgomery County, MS, Oktibbeha County, MS, Pontotoc County, MS, Prentiss County, MS, Sunflower County, MS, Tallahatchie County, MS, Tippah County, MS, Tishomingo County, MS, Union County, MS, Washington County, MS, Webster County, MS, Yalobusha County, MS
The radar
The Columbus AFB radar (KGWX), 78 km from the middle of the area, began a volume at 09:16 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 00:00Z, 9.3 hours before the alert went out and 112 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
- 1725 J/kg
- Mixed-layer CIN
- -13 J/kg
- Mixed-layer LCL
- 759 m above ground
- 0-6 km bulk shear
- 78 kt
- 0-1 km storm-relative helicity
- 398 m²/s²
- 0-3 km storm-relative helicity
- 420 m²/s²
- Significant tornado parameter
- 4.8
- Supercell composite
- 16.2
The text
As transmitted.
101
ACUS11 KWNS 110915
SWOMCD
SPC MCD 110915
ALZ000-TNZ000-MSZ000-111045-
Mesoscale Discussion 2016
NWS Storm Prediction Center Norman OK
0315 AM CST Sat Dec 11 2021
Areas affected...northern and central MS into northwest AL
Concerning...Tornado Watch 558...
Valid 110915Z - 111045Z
The severe weather threat for Tornado Watch 558 continues.
SUMMARY...The threat for a few tornadoes and damaging wind gusts is
increasing across portions of northern/central MS into northwest AL
early this morning.
DISCUSSION...Convection continues to increase in organization and
intensity across portions of northern MS early this morning ahead of
the main band of convection stretching from Middle TN to northern
LA. This convection remains more discrete in a warm sector
characterized by MLCAPE around 1000-1500 J/kg, effective shear 50+
kt and STP values around 2-4. Recent data from the KGWX VWP also
depicts an enlarged, favorably curved low-level hodograph, with very
strong SRH present. As such, the threat for a few tornadoes and
damaging wind gusts is increasing across the MCD area. While
portions of northern MS is within WW 558, this watch expires at 11z
and a new watch will likely need to be issued, and include portions
of central MS into northwest AL.
..Leitman.. 12/11/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OHX...BMX...HUN...MEG...JAN...
LAT...LON 34079032 34718946 34978895 35058840 35038793 34948761
34828746 34618748 34188770 33588833 33348886 33048981
32979032 33019078 33229096 33449091 34079032SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 11, 2:00 AM CST | Mesoscale Discussion | SPC | Colbert, Franklin, Lauderdale, Lawrence, Limestone, Madison and 2 more | 90 min |
| Dec 11, 3:41 AM CST | Tornado Watch | SPC | Colbert, Cullman, DeKalb, Fayette, Franklin, Jackson and 10 more | 6 hr |
| Dec 11, 6:15 AM CST | Mesoscale Discussion | SPC | Cullman, Fayette, Franklin, Jackson, Lamar, Lawrence and 6 more | 90 min |
| Dec 11, 7:34 AM CST | Mesoscale Discussion | SPC | Bibb, Blount, Calhoun, Cherokee, Clay, Cleburne and 8 more | 86 min |
| Dec 11, 10:47 AM CST | Mesoscale Discussion | SPC | Autauga, Bullock, Butler, Chambers, Clarke, Clay and 15 more | 118 min |
| Dec 10, 6:21 PM CST | Tornado Watch | SPC | Alcorn, Benton, Itawamba, Lafayette, Lee, Pontotoc and 4 more | 10 hr |
| Dec 10, 9:40 PM CST | Mesoscale Discussion | SPC | Alcorn, Benton, Coahoma, DeSoto, Lafayette, Marshall and 8 more | 2 hr |
| Dec 10, 10:00 PM CST | Mesoscale Discussion | SPC | Bolivar, Carroll, Claiborne, Hinds, Holmes, Humphreys and 8 more | 90 min |
| Dec 10, 10:09 PM CST | Mesoscale Discussion | SPC | Benton, Bolivar, Calhoun, Carroll, Coahoma, DeSoto and 14 more | 96 min |
| Dec 10, 10:44 PM CST | Tornado Watch | SPC | Alcorn, Benton, Bolivar, Calhoun, Chickasaw, Coahoma and 21 more | 6 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.