Alert archive / Louisiana / Mesoscale Discussions in 2021
Mesoscale Discussion 2000
The Storm Prediction Center issued this mesoscale discussion at Dec 10, 2021, 10:00 PM CST for 4 states. It was in force for 90 min.
The area
The outline as issued.
The facts
- Issued
- Dec 10, 2021, 10:00 PM CST (04:00 UTC)
- Expired
- Dec 10, 2021, 11:30 PM CST
- In force
- 90 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 555
All 60 counties
Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Columbia County, AR, Desha County, AR, Drew County, AR, Lafayette County, AR, Miller County, AR, Ouachita County, AR, Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Richland Parish, LA, Tensas Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Bolivar County, MS, Carroll County, MS, Claiborne County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Leflore County, MS, Madison County, MS, Sharkey County, MS, Sunflower County, MS, Warren County, MS, Washington County, MS, Yazoo County, MS, Camp County, TX, Cass County, TX, Gregg County, TX, Harrison County, TX, Henderson County, TX, Marion County, TX, Morris County, TX, Panola County, TX, Rusk County, TX, Shelby County, TX, Smith County, TX, Upshur County, TX, Wood County, TX
The radar
The Shreveport radar (KSHV), 122 km from the middle of the area, began a volume at 04:01 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
Shreveport, LA (KSHV), launched 00:00Z, 4.0 hours before the alert went out and 113 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
- 1338 J/kg
- Mixed-layer CIN
- -32 J/kg
- Mixed-layer LCL
- 1005 m above ground
- 0-6 km bulk shear
- 63 kt
- 0-1 km storm-relative helicity
- 243 m²/s²
- 0-3 km storm-relative helicity
- 334 m²/s²
- Significant tornado parameter
- 2.6
- Supercell composite
- 10.4
The text
As transmitted.
883
ACUS11 KWNS 110400
SWOMCD
SPC MCD 110400
MSZ000-ARZ000-LAZ000-TXZ000-110530-
Mesoscale Discussion 2000
NWS Storm Prediction Center Norman OK
1000 PM CST Fri Dec 10 2021
Areas affected...portions of far eastern Texas into far southern
Arkansas...northern Louisiana and far western Mississippi
Concerning...Tornado Watch 555...
Valid 110400Z - 110530Z
The severe weather threat for Tornado Watch 555 continues.
SUMMARY...The severe threat persists across southern portions of
Tornado Watch 555. An additional Tornado Watch issuance is likely
farther east into Louisiana, far southern Arkansas and far western
Mississippi.
DISCUSSION...A relatively robust line of storms has recently become
established across far northeastern Texas and is progressing
eastward into a moist, buoyant airmass. At the moment, these storms
just south of Tornado Watch 555 are in a kinematic environment
characterized by strong speed shear, but with modest veering in the
low-levels per latest SHV VWP. However, the storms will progress
farther east into northern LA/southern AR and western MS, in closer
proximity to the LLJ axis. As such, the threat for all severe
hazards (including isolated tornadoes) is expected to increase with
these storms with eastward extent. Since Tornado Watch 555 expires
in an hour, a new downstream Tornado Watch issuance will be needed.
..Squitieri/Grams.. 12/11/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MEG...JAN...LZK...SHV...FWD...
LAT...LON 32319611 32959528 33609364 33829239 33999100 33879035
33708995 33428988 32878985 32299009 31899052 31809089
31659197 31629281 31659390 31889529 32179608 32319611SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 10, 6:22 PM CST | Mesoscale Discussion | SPC | Craighead, Greene, Jackson, Mississippi, Poinsett | 53 min |
| Dec 10, 6:34 PM CST | Tornado Watch | SPC | Columbia, Hempstead, Howard, Lafayette, Little River, Miller and 2 more | 4 hr |
| Dec 10, 6:37 PM CST | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Crawford, Franklin and 10 more | 83 min |
| Dec 10, 6:51 PM CST | Tornado Watch | SPC | Baxter, Benton, Boone, Carroll, Crawford, Franklin and 10 more | 4 hr |
| Dec 10, 7:34 PM CST | Mesoscale Discussion | SPC | Clark, Crittenden, Cross, Faulkner, Garland, Grant and 16 more | 86 min |
| Dec 10, 7:54 PM CST | Mesoscale Discussion | SPC | Boone, Carroll, Crawford, Franklin, Johnson, Logan and 7 more | 2 hr |
| Dec 10, 9:40 PM CST | Mesoscale Discussion | SPC | Arkansas, Clark, Cleveland, Craighead, Crittenden, Cross and 13 more | 2 hr |
| Dec 10, 10:09 PM CST | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 17 more | 96 min |
| Dec 10, 10:44 PM CST | Tornado Watch | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 16 more | 6 hr |
| Dec 11, 2:00 AM CST | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Desha and 4 more | 90 min |
| Dec 11, 1:36 AM CST | Mesoscale Discussion | SPC | Beauregard, Caldwell, De Soto, Grant, LaSalle, Natchitoches and 4 more | 114 min |
| Dec 11, 4:02 AM CST | Mesoscale Discussion | SPC | Allen, Avoyelles, Beauregard, Calcasieu, Caldwell, Catahoula and 9 more | 118 min |
| Dec 10, 6:21 PM CST | Tornado Watch | SPC | Alcorn, Benton, Itawamba, Lafayette, Lee, Pontotoc and 4 more | 10 hr |
| Dec 11, 3:15 AM CST | Mesoscale Discussion | SPC | Alcorn, Benton, Calhoun, Carroll, Chickasaw, Choctaw and 21 more | 90 min |
| Dec 11, 3:41 AM CST | Tornado Watch | SPC | Calhoun, Carroll, Chickasaw, Choctaw, Clay, Grenada and 11 more | 6 hr |
| Dec 11, 6:15 AM CST | Mesoscale Discussion | SPC | Clay, Lowndes, Monroe, Oktibbeha | 90 min |
Nearby
Mesoscale Discussions in Louisiana, 2021Mesoscale Discussions in Mississippi, 2021Mesoscale Discussions in Texas, 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.