Alert archive / Alabama / Mesoscale Discussions in 2021
Mesoscale Discussion 255
The Storm Prediction Center issued this mesoscale discussion at Mar 25, 2021, 12:28 PM CDT for 6 counties in Alabama. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Mar 25, 2021, 12:28 PM CDT (17:28 UTC)
- Expired
- Mar 25, 2021, 2:30 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 50
Counties Bibb County, AL, Calhoun County, AL, Clay County, AL, Cleburne County, AL, Shelby County, AL, Talladega County, AL
The radar
The Birmingham radar (KBMX), 22 km from the middle of the area, began a volume at 17:27 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
Birmingham, AL (KBMX), launched 12:00Z, 5.5 hours before the alert went out and 23 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
- 54 J/kg
- Mixed-layer CIN
- -239 J/kg
- Mixed-layer LCL
- 507 m above ground
- 0-6 km bulk shear
- 65 kt
- 0-1 km storm-relative helicity
- 613 m²/s²
- 0-3 km storm-relative helicity
- 713 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 5.6
The text
As transmitted.
444
ACUS11 KWNS 251728
SWOMCD
SPC MCD 251728
ALZ000-251930-
Mesoscale Discussion 0255
NWS Storm Prediction Center Norman OK
1228 PM CDT Thu Mar 25 2021
Areas affected...parts of central Alabama
Concerning...Tornado Watch 50...
Valid 251728Z - 251930Z
The severe weather threat for Tornado Watch 50 continues.
SUMMARY...A tornadic supercell over northern Hale County may persist
with tornado threat expanding east/northeast for several hours.
DISCUSSION...A long-lived supercell, now tornadic and likely
producing a strong tornado, continues to move east/northeast across
northern Hale County, and has shown no signs of weakening.
The air mass ahead of this cell is unstable and warming as the warm
front continues to lift well northeast of the Birmingham area.
Latest VWP out of BMX shows 0-1 SRH of 329 m2/s2 given a motion of
245/38 kt, which supports a strong tornado.
Given warm/moist advection east of the cell, the tornado threat may
persist for a couple hours as it moves east/northeast across several
counties in Alabama.
..Jewell.. 03/25/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BMX...
LAT...LON 33058763 33818593 33688547 33408529 33218574 32938714
32918757 33058763SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 24, 9:25 PM CDT | Mesoscale Discussion | SPC | Baldwin, Mobile, Washington | 65 min |
| Mar 25, 9:02 AM CDT | Mesoscale Discussion | SPC | Blount, Calhoun, Cherokee, Cleburne, Colbert, Cullman and 21 more | 118 min |
| Mar 25, 10:12 AM CDT | Mesoscale Discussion | SPC | Bibb, Blount, Colbert, Cullman, DeKalb, Etowah and 22 more | 3 hr |
| Mar 25, 10:58 AM CDT | Mesoscale Discussion | SPC | Colbert, Fayette, Franklin, Lamar, Lawrence, Marion and 2 more | 3 hr |
| Mar 25, 11:26 AM CDT | Tornado Watch | SPC | Autauga, Bibb, Blount, Calhoun, Chambers, Cherokee and 39 more | 9 hr |
| Mar 25, 1:24 PM CDT | Mesoscale Discussion | SPC | Colbert, Fayette, Franklin, Greene, Lamar, Lawrence and 4 more | 2 hr |
| Mar 25, 3:45 PM CDT | Mesoscale Discussion | SPC | Bibb, Chilton, Choctaw, Dallas, Greene, Hale and 8 more | 2 hr |
| Mar 25, 4:45 PM CDT | Mesoscale Discussion | SPC | Bibb, Chilton, Coosa, Perry, Shelby, Talladega | 60 min |
| Mar 25, 5:45 PM CDT | Mesoscale Discussion | SPC | Clay, Randolph | 60 min |
Nearby
Mesoscale Discussions in Alabama, 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.