Alert archive / Mississippi / Mesoscale Discussions in 2021
Mesoscale Discussion 2074
The Storm Prediction Center issued this mesoscale discussion at Dec 29, 2021, 2:03 PM CST for 24 counties in Mississippi. It was in force for 87 min.
The area
The outline as issued.
The facts
- Issued
- Dec 29, 2021, 2:03 PM CST (20:03 UTC)
- Expired
- Dec 29, 2021, 3:30 PM CST
- In force
- 87 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
All 24 counties
Adams County, MS, Claiborne County, MS, Copiah County, MS, Covington County, MS, Franklin County, MS, Hinds County, MS, Jasper County, MS, Jefferson County, MS, Jefferson Davis County, MS, Kemper County, MS, Lauderdale County, MS, Lawrence County, MS, Leake County, MS, Lincoln County, MS, Madison County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Warren County, MS, Winston County, MS
The radar
The Jackson/Brandon,MS radar (KDGX), 32 km from the middle of the area, began a volume at 20:04 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 12:00Z, 8.1 hours before the alert went out and 41 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
- 256 J/kg
- Mixed-layer CIN
- -38 J/kg
- Mixed-layer LCL
- 597 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 173 m²/s²
- 0-3 km storm-relative helicity
- 186 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 1.1
The text
As transmitted.
593
ACUS11 KWNS 292003
SWOMCD
SPC MCD 292003
MSZ000-LAZ000-292130-
Mesoscale Discussion 2074
NWS Storm Prediction Center Norman OK
0203 PM CST Wed Dec 29 2021
Areas affected...portions of central MS
Concerning...Severe potential...Watch possible
Valid 292003Z - 292130Z
Probability of Watch Issuance...40 percent
SUMMARY...Potential exists for storms to become severe should they
initiate. If storms develop and mature, damaging gusts and a few
tornadoes would be the primary threats. Convective trends will
continue to be monitored for the need of a WW issuance.
DISCUSSION...South of a 1006 mb surface low and within the open warm
sector, attempts at storm initiation and organization have been
noted along a confluence axis roughly coinciding the LA/MS border.
Agitated CU and occasional low-topped storms continue to become more
widespread with time. However, deep-layer ascent remains relatively
weak across central MS, with low-level convergence being negligible
and upper support drifting away in tandem with an embedded 700 mb
impulse over far western TN. As such, storm coverage and subsequent
intensity are in question.
Nonetheless, 6+ C/km low and mid-level lapse rates overspreading
upper 60s F surface dewpoints, along with ample surface heating, are
contributing to 1000-1500 J/kg MLCAPE, where 45-55 kts of effective
bulk shear is present. In addition, 19Z mesoanalysis shows 150-200
m2/s2 effective SRH across central MS, with both deep and low-level
shear increasing with northward extent. Any storm that can develop,
mature, and become sustained would have the potential to produce
damaging gusts, a few tornadoes, or perhaps a couple of severe
hailstones. However, given the conditional nature of the severe
threat, convective trends will continue to be monitored for the need
of a WW issuance over the next few hours.
..Squitieri/Hart.. 12/29/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...JAN...
LAT...LON 31409151 32199124 32539056 33038926 33328851 33288837
32728838 32328856 32098872 31788934 31478975 31409151SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 29, 10:44 AM CST | Mesoscale Discussion | SPC | Alcorn, Attala, Benton, Bolivar, Calhoun, Carroll and 33 more | 2 hr |
| Dec 29, 12:05 PM CST | Tornado Watch | SPC | Alcorn, Attala, Benton, Bolivar, Calhoun, Carroll and 34 more | 7 hr |
| Dec 29, 1:18 PM CST | Mesoscale Discussion | SPC | Bolivar, Calhoun, Carroll, Chickasaw, Coahoma, Grenada and 15 more | 87 min |
| Dec 29, 2:49 PM CST | Mesoscale Discussion | SPC | Forrest, Lamar, Marion, Pearl River, Perry | 86 min |
| Dec 29, 3:41 PM CST | Mesoscale Discussion | SPC | Alcorn, Benton, Bolivar, Calhoun, Carroll, Chickasaw and 26 more | 64 min |
| Dec 29, 4:38 PM CST | Mesoscale Discussion | SPC | Calhoun, Chickasaw, Clay, Itawamba, Lee, Lowndes and 6 more | 2 hr |
Nearby
Mesoscale Discussions in Mississippi, 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.