Alert archive / Alabama / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 151, NWS Birmingham, AL

October 4, 2021Shelby County, Alabama

NWS Birmingham, AL issued this severe thunderstorm warning at Oct 4, 2021, 5:43 PM CDT for Shelby County, Alabama. It was in force for 47 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Oct 4, 2021, 5:43 PM CDT (22:43 UTC)
Expired: Oct 4, 2021, 6:30 PM CDT
In force: 47 min
Issued by: NWS Birmingham, AL
Area: Storm-based polygon
Hail: 0.88 in
Wind: 60.0 mph

County Shelby County, AL

The radar

The Birmingham radar (KBMX), 15 km from the middle of the area, began a volume at 22:44 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.

What was reported inside it

Time	Report	Where	Remark
Oct 4, 5:44 PM CDT	HAIL 0.75	2 Ne Helena, AL
Oct 4, 5:49 PM CDT	HAIL 0.5	2 Ne Pelham, AL	SMALL HAIL ALONG I-65.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Birmingham, AL (KBMX), launched 12:00Z, 10.7 hours before the alert went out and 14 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 565 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 616 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 34 m²/s²
0-3 km storm-relative helicity: 69 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

As transmitted.

470 
WUUS54 KBMX 042243
SVRBMX
ALC117-042330-
/O.NEW.KBMX.SV.W.0151.211004T2243Z-211004T2330Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Birmingham AL
543 PM CDT Mon Oct 4 2021

The National Weather Service in Birmingham has issued a

* Severe Thunderstorm Warning for...
  Central Shelby County in central Alabama...

* Until 630 PM CDT.

* At 542 PM CDT, a severe thunderstorm was located over Pelham, and
  is nearly stationary.

  HAZARD...60 mph wind gusts and nickel size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations impacted include...
  Hoover, Alabaster, Pelham, Helena, Indian Springs Village,
  Riverchase, Oak Mountain Amphitheater, Oak Mountain State Park, Joe
  Tucker Park and Ballantrae.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3325 8673 3325 8686 3333 8687 3333 8683
      3335 8683 3336 8673
TIME...MOT...LOC 2242Z 272DEG 1KT 3331 8681 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.88 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

25/Owen

1 follow-up statement

359 
WWUS54 KBMX 042320 RRA
SVSBMX

Severe Weather Statement
National Weather Service Birmingham AL
620 PM CDT Mon Oct 4 2021

ALC117-042330-
/O.EXP.KBMX.SV.W.0151.000000T0000Z-211004T2330Z/
Shelby AL-
620 PM CDT Mon Oct 4 2021

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL SHELBY COUNTY WILL
EXPIRE AT 630 PM CDT...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire.

LAT...LON 3325 8673 3325 8686 3333 8687 3333 8683
      3335 8683 3336 8673
TIME...MOT...LOC 2320Z 272DEG 1KT 3331 8680 

$$

25/Owen

The office that day

Everything else NWS Birmingham, AL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 3, 8:04 PM CDT	Areal Flood Advisory	BMX	Fayette, Walker	116 min
Oct 3, 9:05 PM CDT	Flash Flood Warning	BMX	Fayette, Jefferson, Marion, Walker	3 hr
Oct 3, 10:59 PM CDT	Areal Flood Advisory	BMX	Jefferson	3 hr
Oct 4, 12:53 AM CDT	Areal Flood Advisory	BMX	Jefferson, St. Clair, Shelby	3 hr
Oct 4, 1:23 AM CDT	Dense Fog Advisory	BMX	Blount, Fayette, Lamar, Marion, Pickens, Tuscaloosa and 2 more	8 hr
Oct 4, 3:11 AM CDT	Flash Flood Watch	BMX	Autauga, Barbour, Bibb, Blount, Bullock, Calhoun and 30 more	3 days
Oct 4, 9:37 AM CDT	Areal Flood Advisory	BMX	Lee	3 hr
Oct 4, 11:51 AM CDT	Areal Flood Advisory	BMX	Russell	3 hr
Oct 4, 12:20 PM CDT	Flash Flood Warning	BMX	Lee, Russell	3 hr
Oct 4, 12:44 PM CDT	Areal Flood Advisory	BMX	Lowndes, Montgomery	3 hr
Oct 4, 1:33 PM CDT	Flash Flood Warning	BMX	Montgomery	87 min
Oct 4, 3:12 PM CDT	Special Weather Statement	BMX	Coosa	33 min
Oct 4, 3:21 PM CDT	Flash Flood Warning	BMX	Lee, Russell	3 hr
Oct 4, 3:28 PM CDT	Flash Flood Warning	BMX	Lowndes, Montgomery	3 hr
Oct 4, 4:40 PM CDT	Areal Flood Advisory	BMX	Chilton, Coosa	3 hr
Oct 4, 4:56 PM CDT	Flash Flood Warning	BMX	Chilton	3 hr
Oct 4, 5:09 PM CDT	Special Weather Statement	BMX	Bibb	36 min
Oct 4, 5:09 PM CDT	Special Weather Statement	BMX	Shelby	36 min
Oct 4, 5:16 PM CDT	Severe Thunderstorm Warning	BMX	Bibb	29 min
Oct 4, 5:22 PM CDT	Special Weather Statement	BMX	Shelby	23 min
Oct 4, 5:47 PM CDT	Severe Thunderstorm Warning	BMX	Bibb, Shelby	43 min
Oct 4, 6:02 PM CDT	Special Weather Statement	BMX	Shelby	28 min
Oct 4, 6:17 PM CDT	Special Weather Statement	BMX	Jefferson	28 min
Oct 4, 6:34 PM CDT	Special Weather Statement	BMX	Jefferson	26 min

Nearby

Severe Thunderstorm Warnings in Alabama, 2021 Every severe thunderstorm warning 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.