Alert archive / Alabama / Mesoscale Discussions in 2021
Mesoscale Discussion 1672
The Storm Prediction Center issued this mesoscale discussion at Sep 1, 2021, 2:35 PM CDT for 22 counties in Alabama. It was in force for 115 min.
The area
The outline as issued.
The facts
- Issued
- Sep 1, 2021, 2:35 PM CDT (19:35 UTC)
- Expired
- Sep 1, 2021, 4:30 PM CDT
- In force
- 115 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
All 22 counties
Autauga County, AL, Barbour County, AL, Bibb County, AL, Bullock County, AL, Butler County, AL, Chilton County, AL, Coosa County, AL, Crenshaw County, AL, Dallas County, AL, Elmore County, AL, Hale County, AL, Jefferson County, AL, Lee County, AL, Lowndes County, AL, Macon County, AL, Montgomery County, AL, Perry County, AL, Pike County, AL, Russell County, AL, Shelby County, AL, Tallapoosa County, AL, Tuscaloosa County, AL
The radar
The Maxwell AFB radar (KMXX), 62 km from the middle of the area, began a volume at 19:36 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, 7.6 hours before the alert went out and 69 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
- 170 J/kg
- Mixed-layer CIN
- -55 J/kg
- Mixed-layer LCL
- 990 m above ground
- 0-6 km bulk shear
- 20 kt
- 0-1 km storm-relative helicity
- 51 m²/s²
- 0-3 km storm-relative helicity
- 52 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
997
ACUS11 KWNS 011936
SWOMCD
SPC MCD 011935
ALZ000-012130-
Mesoscale Discussion 1672
NWS Storm Prediction Center Norman OK
0235 PM CDT Wed Sep 01 2021
Areas affected...Portions of central and southern Alabama
Concerning...Severe potential...Watch unlikely
Valid 011935Z - 012130Z
Probability of Watch Issuance...5 percent
SUMMARY...A cluster of strong thunderstorms may pose a risk for a
few strong wind gusts/downbursts this afternoon.
DISCUSSION...As of 1915 UTC, regional radar imagery showed a cluster
of thunderstorms across central Alabama moving south-southeastward
at around 25 kt. Ongoing within a weakly forced but warm, moist, and
unstable environment (1500-2000 J/kg of MLCAPE) these storms are
forecast to continue to move southeastward across portions of
central and southern Alabama this afternoon. Model soundings and
regional VADs show little deep-layer shear owing to weak
northwesterly flow aloft less that 20 kt. This suggest any
convective organization will be limited and tied to the strength of
the southeastward propagating cold pool. DCAPE values around
1200-1400 J/kg may support a few stronger downdrafts capable of
isolated damaging wind gusts this afternoon and evening before the
cluster weakens with the loss of diurnal heating. Given the limited
threat for organized severe weather a watch is unlikely.
..Lyons/Grams.. 09/01/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TAE...BMX...MOB...
LAT...LON 33388740 33708696 33708668 33248599 33058557 32718525
32408510 32268509 31748541 31468573 31268665 31628688
32058721 32828785 33208796 33388740Nearby
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.