Alert archive / Alabama / Mesoscale Discussions in 2021
Mesoscale Discussion 426
The Storm Prediction Center issued this mesoscale discussion at Apr 24, 2021, 3:40 PM CDT for 25 counties in Alabama; Holmes County, Santa Rosa County, Florida. It was in force for 95 min.
The area
The outline as issued.
The facts
- Issued
- Apr 24, 2021, 3:40 PM CDT (20:40 UTC)
- Expired
- Apr 24, 2021, 5:15 PM CDT
- In force
- 95 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 108
All 27 counties
Autauga County, AL, Barbour County, AL, Bullock County, AL, Butler County, AL, Clarke County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Dallas County, AL, Elmore County, AL, Escambia County, AL, Geneva County, AL, Henry County, AL, Houston County, AL, Lowndes County, AL, Macon County, AL, Marengo County, AL, Monroe County, AL, Montgomery County, AL, Pike County, AL, Russell County, AL, Washington County, AL, Wilcox County, AL, Holmes County, FL, Santa Rosa County, FL
The radar
The Ft Rucker radar (KEOX), 134 km from the middle of the area, began a volume at 20:44 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, 8.7 hours before the alert went out and 176 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 580 m above ground
- 0-6 km bulk shear
- 62 kt
- 0-1 km storm-relative helicity
- 855 m²/s²
- 0-3 km storm-relative helicity
- 1103 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
460
ACUS11 KWNS 242040
SWOMCD
SPC MCD 242040
GAZ000-FLZ000-ALZ000-MSZ000-242215-
Mesoscale Discussion 0426
NWS Storm Prediction Center Norman OK
0340 PM CDT Sat Apr 24 2021
Areas affected...portions of central into southern Alabama...western
Florida Panhandle
Concerning...Severe Thunderstorm Watch 108...
Valid 242040Z - 242215Z
The severe weather threat for Severe Thunderstorm Watch 108
continues.
SUMMARY...The severe threat is expected to continue across Severe
Thunderstorm Watch #108. Large hail remains the primary threat with
the stronger, longer lived storms, though a couple damaging gusts
and perhaps a tornado cannot be ruled out.
DISCUSSION...Storm coverage has increased across Severe Thunderstorm
Watch #108 over the past couple of hours, with semi-discrete
cellular clusters and a couple of supercells noted across southern
AL. MRMS mosaic MESH radar data suggests that over 1.0 inch in
diameter hail may be occurring with the more mature supercell
structures, particularly in storms with 50+ dBZ echoes exceeding 30
kft. Near 70F dewpoints overspread by adequately steep low and
mid-level lapse rates are promoting 1500-2000 J/kg MLCAPE across the
area, suggesting that vigorous updrafts may continue to support a
primary threat of large hail threat for at least the next few hours.
MOB and EOX VWPs depict over 200 m2/s2 0-3km SRH, but with either
small-looping or nearly straight hodographs, suggesting that storm
rotation may be relatively confined to the mid-levels. However,
transient low-level rotation supporting a couple damaging gusts and
perhaps a brief tornado remains possible.
..Squitieri/Hart.. 04/24/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FFC...TAE...BMX...MOB...
LAT...LON 31628855 32258786 32508729 32668610 32608548 32218506
31618504 31118513 30708566 30628686 30698776 30898824
31298855 31628855SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 24, 1:00 AM CDT | Mesoscale Discussion | SPC | Baldwin, Coffee, Conecuh, Covington, Escambia, Geneva and 2 more | 3 hr |
| Apr 24, 1:00 AM CDT | Mesoscale Discussion | SPC | Baldwin, Coffee, Conecuh, Covington, Escambia, Geneva and 2 more | 3 hr |
| Apr 24, 1:23 AM CDT | Tornado Watch | SPC | Baldwin, Clarke, Conecuh, Covington, Escambia, Mobile and 2 more | 8 hr |
| Apr 24, 3:04 AM CDT | Mesoscale Discussion | SPC | Baldwin, Mobile, Washington | 116 min |
| Apr 24, 4:26 AM CDT | Mesoscale Discussion | SPC | Conecuh, Covington, Escambia, Monroe, Washington | 2 hr |
| Apr 24, 5:22 AM CDT | Tornado Watch | SPC | Coffee, Dale, Geneva, Henry, Houston | 9 hr |
| Apr 24, 7:29 AM CDT | Mesoscale Discussion | SPC | Coffee, Dale, Geneva, Henry, Houston | 91 min |
| Apr 24, 12:29 PM CDT | Mesoscale Discussion | SPC | Baldwin, Choctaw, Clarke, Conecuh, Escambia, Marengo and 4 more | 2 hr |
| Apr 24, 1:17 PM CDT | Severe Thunderstorm Watch | SPC | Autauga, Baldwin, Barbour, Bullock, Butler, Choctaw and 23 more | 8 hr |
| Apr 24, 1:22 PM CDT | Mesoscale Discussion | SPC | Blount, Calhoun, Cherokee, Clay, Cleburne, Colbert and 22 more | 113 min |
| Apr 24, 4:52 PM CDT | Severe Thunderstorm Watch | SPC | Bibb, Blount, Calhoun, Chambers, Cherokee, Chilton and 15 more | 4 hr |
| Apr 24, 5:56 PM CDT | Mesoscale Discussion | SPC | Barbour, Bullock, Coffee, Dale, Henry, Houston and 1 more | 94 min |
| Apr 24, 6:13 PM CDT | Mesoscale Discussion | SPC | Calhoun, Chambers, Cherokee, Clay, Cleburne, Coosa and 6 more | 2 hr |
| Apr 24, 9:10 AM CDT | Mesoscale Discussion | SPC | Nassau | 95 min |
| Apr 24, 9:35 AM CDT | Tornado Watch | SPC | Baker, Columbia, Duval, Hamilton, Nassau, Suwannee | 7 hr |
| Apr 24, 11:05 AM CDT | Mesoscale Discussion | SPC | Calhoun, Gadsden, Holmes, Jackson, Jefferson, Leon and 4 more | 85 min |
| Apr 24, 3:35 PM CDT | Mesoscale Discussion | SPC | Duval, Nassau | 85 min |
Nearby
Mesoscale Discussions in Alabama, 2021Mesoscale Discussions in Florida, 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.