Alert archive / Alabama / Mesoscale Discussions in 2021
Mesoscale Discussion 489
The Storm Prediction Center issued this mesoscale discussion at May 3, 2021, 10:38 AM CDT for 13 counties in Alabama. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- May 3, 2021, 10:38 AM CDT (15:38 UTC)
- Expired
- May 3, 2021, 12:15 PM CDT
- In force
- 97 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
Counties Butler County, AL, Clarke County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dallas County, AL, Escambia County, AL, Lowndes County, AL, Monroe County, AL, Montgomery County, AL, Pike County, AL, Washington County, AL, Wilcox County, AL
The radar
The Ft Rucker radar (KEOX), 141 km from the middle of the area, began a volume at 15:41 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, 3.6 hours before the alert went out and 170 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
- 1106 J/kg
- Mixed-layer CIN
- -20 J/kg
- Mixed-layer LCL
- 552 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 313 m²/s²
- 0-3 km storm-relative helicity
- 363 m²/s²
- Significant tornado parameter
- 1.7
- Supercell composite
- 11.4
The text
As transmitted.
839
ACUS11 KWNS 031538
SWOMCD
SPC MCD 031538
ALZ000-MSZ000-031715-
Mesoscale Discussion 0489
NWS Storm Prediction Center Norman OK
1038 AM CDT Mon May 03 2021
Areas affected...southern Alabama
Concerning...Severe potential...Watch possible
Valid 031538Z - 031715Z
Probability of Watch Issuance...60 percent
SUMMARY...Storms may become capable of producing mainly isolated
damaging wind and hail this afternoon. Trends are being monitored
for a possible WW.
DISCUSSION...Latest radar trends show storms continue to increase in
coverage in the warm sector across southern AL. This activity is
developing along cloud streets as the boundary layer destabilizes,
supporting MLCAPE to 2000 J/kg, but with weak mid-level lapse rates.
Activity is primarily diurnally driven within a weakly capped but
moist environment. Vertical wind profiles will remain modest with
30-35 kt effective bulk shear supporting multicell and occasional
marginal supercell structures. Isolated damaging wind appears to be
the main threat, but some hail and perhaps a brief tornado or two
cannot be ruled out.
..Dial/Grams.. 05/03/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TAE...BMX...MOB...
LAT...LON 31248603 30968785 31308846 32158792 32588634 32118586
31248603SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 2, 11:45 PM CDT | Mesoscale Discussion | SPC | Colbert, Franklin, Marion | 2 hr |
| May 3, 9:29 AM CDT | Tornado Watch | SPC | Bullock, Chambers, Clay, Cleburne, Coosa, Elmore and 6 more | 5 hr |
| May 3, 11:47 AM CDT | Severe Thunderstorm Watch | SPC | Autauga, Barbour, Bibb, Blount, Bullock, Butler and 46 more | 10 hr |
| May 3, 4:00 PM CDT | Mesoscale Discussion | SPC | Autauga, Barbour, Bibb, Bullock, Butler, Calhoun and 38 more | 90 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.