Alert archive / Alabama / Special Weather Statements in 2021

Special Weather Statement, NWS Birmingham, AL

July 30, 2021St. Clair County, Alabama

NWS Birmingham, AL issued this special weather statement at Jul 30, 2021, 6:21 PM CDT for St. Clair County, Alabama. It was in force for 24 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Jul 30, 2021, 6:21 PM CDT (23:21 UTC)
Expired
Jul 30, 2021, 6:45 PM CDT
In force
24 min
Issued by
NWS Birmingham, AL

County St. Clair County, AL

The radar

The Birmingham radar (KBMX), 89 km from the middle of the area, began a volume at 23:26 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, 11.4 hours before the alert went out and 89 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-pSkew-T log-p diagram, Birmingham, AL at 12:00Z on 2021-07-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1105 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Birmingham, AL at 12:00Z on 2021-07-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -22 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
1105 J/kg
Mixed-layer CIN
-98 J/kg
Mixed-layer LCL
1087 m above ground
0-6 km bulk shear
4 kt
0-1 km storm-relative helicity
-22 m²/s²
0-3 km storm-relative helicity
-15 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

551 
WWUS84 KBMX 302321
SPSBMX

Special Weather Statement
National Weather Service Birmingham AL
621 PM CDT Fri Jul 30 2021
 
ALZ026-302345-
St. Clair AL-
621 PM CDT Fri Jul 30 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN ST. CLAIR COUNTY
UNTIL 645 PM CDT...

At 621 PM CDT, Doppler radar was tracking a strong thunderstorm near
Steele, or 10 miles east of Oneonta, moving southeast at 20 mph.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Ashville, Ragland, Steele, Neely Henry Lake, Logan Martin Lake,
Whitney Junction, Alabama International Dragway, Neely Henry Dam,
Horse Pens Forty, I 59 Rest Areas At Oneonta and Camp Sumatanga.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3390 8614 3389 8611 3386 8610 3387 8607
      3385 8605 3381 8607 3377 8604 3371 8613
      3371 8614 3368 8617 3370 8618 3370 8620
      3368 8620 3367 8619 3364 8623 3387 8636
      3389 8634 3391 8635 3393 8632 3398 8622
TIME...MOT...LOC 2321Z 320DEG 18KT 3392 8629 

$$

CBD

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 30, 4:28 PM CDTSpecial Weather StatementBMXEtowah47 min
Jul 30, 4:36 PM CDTSpecial Weather StatementBMXFayette24 min
Jul 30, 5:08 PM CDTSpecial Weather StatementBMXBlount37 min
Jul 30, 5:44 PM CDTSpecial Weather StatementBMXCalhoun31 min
Jul 30, 6:08 PM CDTSpecial Weather StatementBMXJefferson37 min
Jul 30, 6:16 PM CDTSpecial Weather StatementBMXCherokee14 min

Nearby

Special Weather Statements in Alabama, 2021Every special weather statement 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.