Alert archive / Mississippi / Mesoscale Discussions in 2018
Mesoscale Discussion 252
The Storm Prediction Center issued this mesoscale discussion at Apr 14, 2018, 4:35 AM CDT for 7 counties in Alabama; 38 counties in Mississippi; 4 counties in Tennessee. It was in force for 115 min.
The area
The outline as issued.
The facts
- Issued
- Apr 14, 2018, 4:35 AM CDT (09:35 UTC)
- Expired
- Apr 14, 2018, 6:30 AM CDT
- In force
- 115 min
- Issued by
- the Storm Prediction Center
All 49 counties
Colbert County, AL, Fayette County, AL, Franklin County, AL, Lamar County, AL, Lauderdale County, AL, Marion County, AL, Pickens County, AL, Alcorn County, MS, Attala 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, Issaquena County, MS, Itawamba County, MS, Lafayette County, MS, Leake County, MS, Lee County, MS, Leflore County, MS, Lowndes County, MS, Madison County, MS, Marshall County, MS, Monroe County, MS, Montgomery County, MS, Noxubee County, MS, Oktibbeha County, MS, Panola County, MS, Pontotoc County, MS, Prentiss County, MS, Quitman County, MS, Sharkey County, MS, Sunflower County, MS, Tallahatchie County, MS, Tippah County, MS, Tishomingo County, MS, Union County, MS, Webster County, MS, Winston County, MS, Yalobusha County, MS, Yazoo County, MS, Chester County, TN, Hardeman County, TN, Hardin County, TN, McNairy County, TN
The radar
The Columbus AFB radar (KGWX), 57 km from the middle of the area, began a volume at 09:35 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 (KBYH), launched 00:00Z, 9.6 hours before the alert went out and 133 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
- 1321 J/kg
- Mixed-layer CIN
- -1 J/kg
- Mixed-layer LCL
- 505 m above ground
- 0-6 km bulk shear
- 45 kt
- 0-1 km storm-relative helicity
- 449 m²/s²
- 0-3 km storm-relative helicity
- 495 m²/s²
- Significant tornado parameter
- 3.4
- Supercell composite
- 17.1
The text
As transmitted.
495
ACUS11 KWNS 140936
SWOMCD
SPC MCD 140935
ALZ000-TNZ000-MSZ000-LAZ000-141130-
Mesoscale Discussion 0252
NWS Storm Prediction Center Norman OK
0435 AM CDT Sat Apr 14 2018
Areas affected...the northern half of Mississippi and adjacent parts
of southwest Tennessee and northwest Alabama
Concerning...Tornado Watch 46...
Valid 140935Z - 141130Z
The severe weather threat for Tornado Watch 46 continues.
SUMMARY...Local risk for gusty/damaging winds and a brief tornado or
two continues across portions of Tornado Watch 46. The need for a
future/downstream watch remains uncertain.
DISCUSSION...Latest radar loop shows a slowly decaying band of
storms crossing the Mississippi River at this time. The strongest
remaining portion of the line extends from near the
Tennessee/Mississippi border southwest across the Delta region,
where the severe/brief tornado risk is the greatest.
Storms should remain largely contained within WW 46 through its
scheduled 11Z expiration. The need for a downstream watch remains
uncertain, though low-level moistening indicated ahead of the line
by surface obs over the past 1-2 hours may allow enough severe
threat to linger (given the adequately sheared environment) to
warrant new watch consideration.
..Goss.. 04/14/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OHX...BMX...HUN...MEG...JAN...
LAT...LON 33628780 32908845 32559042 32589118 34029061 34868965
35408927 35508820 34658740 33958754 33628780SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 14, 6:37 AM CDT | Mesoscale Discussion | SPC | Sumter | 83 min |
| Apr 14, 9:40 AM CDT | Mesoscale Discussion | SPC | Autauga, Baldwin, Bibb, Butler, Chilton, Choctaw and 18 more | 95 min |
| Apr 14, 10:36 AM CDT | Tornado Watch | SPC | Autauga, Baldwin, Bibb, Blount, Butler, Chilton and 22 more | 8 hr |
| Apr 14, 12:41 PM CDT | Mesoscale Discussion | SPC | Autauga, Baldwin, Bibb, Butler, Chilton, Choctaw and 18 more | 94 min |
| Apr 14, 2:56 PM CDT | Mesoscale Discussion | SPC | Autauga, Chilton, Coosa, Dallas, Lowndes, Mobile and 5 more | 94 min |
| Apr 14, 6:17 PM CDT | Mesoscale Discussion | SPC | Baldwin, Butler, Clarke, Conecuh, Covington, Escambia and 2 more | 118 min |
| Apr 14, 6:55 PM CDT | Tornado Watch | SPC | Baldwin, Butler, Clarke, Conecuh, Covington, Crenshaw and 7 more | 6 hr |
| Apr 13, 7:22 PM CDT | Tornado Watch | SPC | Adams, Bolivar, Claiborne, Franklin, Issaquena, Jefferson and 4 more | 3 hr |
| Apr 13, 10:12 PM CDT | Tornado Watch | SPC | Adams, Alcorn, Benton, Bolivar, Calhoun, Carroll and 33 more | 10 hr |
| Apr 14, 2:10 AM CDT | Mesoscale Discussion | SPC | Adams, Attala, Benton, Bolivar, Calhoun, Carroll and 32 more | 2 hr |
| Apr 14, 6:57 AM CDT | Tornado Watch | SPC | Amite, Attala, Choctaw, Clarke, Clay, Copiah and 30 more | 7 hr |
Nearby
Mesoscale Discussions in Mississippi, 2018Mesoscale Discussions in Alabama, 2018Mesoscale Discussions in Tennessee, 2018Every mesoscale discussion in 2018
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.