Alert archive / Alabama / Mesoscale Discussions in 2017
Mesoscale Discussion 613
The Storm Prediction Center issued this mesoscale discussion at Apr 30, 2017, 10:06 AM CDT for 22 counties in Alabama; 8 counties in Mississippi. It was in force for 84 min.
The area
The outline as issued.
The facts
- Issued
- Apr 30, 2017, 10:06 AM CDT (15:06 UTC)
- Expired
- Apr 30, 2017, 11:30 AM CDT
- In force
- 84 min
- Issued by
- the Storm Prediction Center
All 30 counties
Autauga County, AL, Bibb County, AL, Chilton County, AL, Colbert County, AL, Coosa County, AL, Cullman County, AL, Dallas County, AL, Fayette County, AL, Franklin County, AL, Greene County, AL, Hale County, AL, Jefferson County, AL, Lamar County, AL, Lawrence County, AL, Marengo County, AL, Marion County, AL, Perry County, AL, Pickens County, AL, Shelby County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL, Chickasaw County, MS, Itawamba County, MS, Lee County, MS, Monroe County, MS, Pontotoc County, MS, Prentiss County, MS, Tishomingo County, MS, Union County, MS
The radar
The Columbus AFB radar (KGWX), 56 km from the middle of the area, began a volume at 15:08 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
Birmingham, AL (KBMX), launched 12:00Z, 3.1 hours before the alert went out and 110 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
- 53 J/kg
- Mixed-layer CIN
- -333 J/kg
- Mixed-layer LCL
- 867 m above ground
- 0-6 km bulk shear
- 22 kt
- 0-1 km storm-relative helicity
- 32 m²/s²
- 0-3 km storm-relative helicity
- 224 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
881
ACUS11 KWNS 301506
SWOMCD
SPC MCD 301506
ALZ000-MSZ000-301630-
Mesoscale Discussion 0613
NWS Storm Prediction Center Norman OK
1006 AM CDT Sun Apr 30 2017
Areas affected...northeast Mississippi through central and northern
Alabama
Concerning...Tornado Watch 181...
Valid 301506Z - 301630Z
The severe weather threat for Tornado Watch 181 continues.
SUMMARY...The threat for mainly isolated damaging wind and a few
tornadoes is expected to persist across the remainder of WW 181
including eastern MS and southeast LA. Based on current trends, a
downstream tornado watch will probably be needed prior to 16Z that
would include northeast MS and portions of central and northern AL.
DISCUSSION...Line of strong to severe storms continues advancing
east at 35-40 kt through MS with embedded organized structures
evident including meso-vortices as well as a book-end vortex and
bowing segment over central MS. The 12Z RAOB from Birmingham AL
showed limited instability, substantial capping inversion and weak
0-6 km vertical shear. However, winds aloft will gradually
strengthen farther east today as a mid-level jet rotates newd
through the eastern periphery of upper low circulation. Though
widespread multi-layer clouds will slow diabatic warming of boundary
layer, at least weak theta-e advection along the strong southerly
low-level jet and some cloud breaks should contribute to 500-1000
J/kg MLCAPE and weakening convective inhibition. These processes
might be sufficient to sustain a severe threat farther east into AL
into the afternoon.
..Dial.. 04/30/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BMX...HUN...MOB...MEG...JAN...
LAT...LON 33868929 34758890 34808762 34168667 32798611 32198662
32238807 33528824 33868929SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 30, 10:36 AM CDT | Tornado Watch | SPC | Autauga, Baldwin, Bibb, Blount, Chilton, Choctaw and 27 more | 8 hr |
| Apr 30, 1:21 PM CDT | Mesoscale Discussion | SPC | Cherokee, Cleburne, DeKalb, Etowah, Jackson, Madison and 1 more | 54 min |
| Apr 30, 1:36 PM CDT | Tornado Watch | SPC | Calhoun, Chambers, Cherokee, Clay, Cleburne, Coosa and 10 more | 5 hr |
| Apr 30, 3:42 PM CDT | Mesoscale Discussion | SPC | Autauga, Calhoun, Chambers, Cherokee, Clay, Cleburne and 8 more | 2 hr |
| Apr 30, 12:54 AM CDT | Mesoscale Discussion | SPC | Bolivar, Coahoma, DeSoto, Panola, Quitman, Sunflower and 3 more | 96 min |
| Apr 30, 1:10 AM CDT | Severe Thunderstorm Watch | SPC | DeSoto, Tunica | 6 hr |
| Apr 30, 1:14 AM CDT | Mesoscale Discussion | SPC | Adams, Claiborne, Jefferson, Wilkinson | 91 min |
| Apr 30, 1:49 AM CDT | Tornado Watch | SPC | Adams, Claiborne, Franklin, Issaquena, Jefferson, Sharkey and 3 more | 7 hr |
| Apr 30, 2:58 AM CDT | Mesoscale Discussion | SPC | DeSoto, Marshall, Tate, Tunica | 92 min |
| Apr 30, 5:41 AM CDT | Mesoscale Discussion | SPC | DeSoto, Tunica | 64 min |
| Apr 30, 6:12 AM CDT | Mesoscale Discussion | SPC | Adams, Amite, Claiborne, Franklin, Issaquena, Jefferson and 4 more | 93 min |
| Apr 30, 6:59 AM CDT | Mesoscale Discussion | SPC | Amite, Attala, Calhoun, Carroll, Chickasaw, Choctaw and 50 more | 2 hr |
| Apr 30, 7:32 AM CDT | Tornado Watch | SPC | Amite, Attala, Carroll, Choctaw, Clarke, Clay and 42 more | 7 hr |
Nearby
Mesoscale Discussions in Alabama, 2017Mesoscale Discussions in Mississippi, 2017Every mesoscale discussion in 2017
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.