Alert archive / Alabama / Mesoscale Discussions in 2021
Mesoscale Discussion 262
The Storm Prediction Center issued this mesoscale discussion at Mar 25, 2021, 5:45 PM CDT for Clay County, Randolph County, Alabama. It was in force for 60 min.
The area
The outline as issued.
The facts
- Issued
- Mar 25, 2021, 5:45 PM CDT (22:45 UTC)
- Expired
- Mar 25, 2021, 6:45 PM CDT
- In force
- 60 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 50
Counties Clay County, AL, Randolph County, AL
The radar
The Birmingham radar (KBMX), 86 km from the middle of the area, began a volume at 22:48 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, 10.8 hours before the alert went out and 87 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.
409 ACUS11 KWNS 252246 SWOMCD SPC MCD 252245 ALZ000-252345- Mesoscale Discussion 0262 NWS Storm Prediction Center Norman OK 0545 PM CDT Thu Mar 25 2021 Areas affected...parts of eastern AL Concerning...Tornado Watch 50... Valid 252245Z - 252345Z The severe weather threat for Tornado Watch 50 continues. SUMMARY...Strong to intense tornado potential will rapidly increase coincident with the central AL supercell moving into eastern AL. DISCUSSION...5pm CDT surface mesoanalysis indicates a low-level moisture axis (featuring upper 60s F dewpoints) extending from southwestern AL to I-65 in central AL immediately ahead of the tornadic supercell. Farther east over eastern AL, surface dewpoints are in the middle to upper 60s. Forecast soundings (NAM/RAP) both indicate a slight increase in moisture will occur over the next hour across eastern AL ahead of the supercell. As a result, it seems that moisture quality will remain relatively similar across eastern AL as it is as of 5pm across the I-65 corridor. The KMXX VAD is showing similar 500-mb flow as KBMX and KFFC. Given objective analysis indicating 300-400 m2/s2 0-1 km SRH, it seems plausible the tornado risk will continue relatively uninterrupted over the next 1-2 hours as the storm moves towards the AL/GA border. Some cellular interference from the south in the near term may briefly limit overall tornado potential, but once storm interference from the south ceases/relaxes, additional tornadoes (including a strong to intense tornado) are possible through 7pm CDT over eastern AL. ..Smith.. 03/25/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BMX... LAT...LON 33508608 33658539 33248533 32928646 33508608
SPC 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, 12:28 PM CDT | Mesoscale Discussion | SPC | Bibb, Calhoun, Clay, Cleburne, Shelby, Talladega | 2 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 |
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.