Alert archive / Alabama / Flash Flood Watches in 2020

Flash Flood Watch 12, NWS Birmingham, AL

August 28, 202019 counties in Alabama

NWS Birmingham, AL issued this flash flood watch at Aug 28, 2020, 11:10 AM CDT for 19 counties in Alabama. It was in force for 7 hr.

The area

The counties it named.

The facts

Issued
Aug 28, 2020, 11:10 AM CDT (16:10 UTC)
Expired
Aug 28, 2020, 5:47 PM CDT
In force
7 hr
Issued by
NWS Birmingham, AL
Flood severity
None

Counties Bibb County, AL, Blount County, AL, Calhoun County, AL, Cherokee County, AL, Chilton County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Etowah County, AL, Greene County, AL, Hale County, AL, Jefferson County, AL, Marengo County, AL, Perry County, AL, Shelby County, AL, St. Clair County, AL, Sumter County, AL, Talladega County, AL, Tuscaloosa County, AL

The radar

The Birmingham radar (KBMX), 11 km from the middle of the area, began a volume at 16:13 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, 4.2 hours before the alert went out and 10 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 2020-08-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 981 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Birmingham, AL at 12:00Z on 2020-08-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 78 square meters per square second.193958Sfc1 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
981 J/kg
Mixed-layer CIN
-6 J/kg
Mixed-layer LCL
576 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
78 m²/s²
0-3 km storm-relative helicity
71 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.3

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Birmingham, AL wrote its last area forecast discussion before this flash flood watch went out at Aug 28, 10:38 AM CDT, 32 minutes earlier.

Area forecast discussion, Aug 28, 10:38 AM CDT, 32 minutes before
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Hazardous weather outlook, Aug 28, 4:56 AM CDT, 6 hours 14 minutes before
Hazardous Weather Outlook
National Weather Service Birmingham AL
456 AM CDT Fri Aug 28 2020

ALZ011>015-017>050-291300-
Marion-Lamar-Fayette-Winston-Walker-Blount-Etowah-Calhoun-Cherokee-
Cleburne-Pickens-Tuscaloosa-Jefferson-Shelby-St. Clair-Talladega-
Clay-Randolph-Sumter-Greene-Hale-Perry-Bibb-Chilton-Coosa-Tallapoosa-
Chambers-Marengo-Dallas-Autauga-Lowndes-Elmore-Montgomery-Macon-
Bullock-Lee-Russell-Pike-Barbour-
456 AM CDT Fri Aug 28 2020

This Hazardous Weather Outlook is for the counties served by the
National Weather Service office in Birmingham.

.DAY ONE...Outlook through Tonight.

The remnants of Laura may bring a threat for damaging winds and a
brief tornado between Noon and 10 PM. Areas with greatest potential
will be along and northwest of an Aliceville to Warrior line, with a
marginal risk along and north of a Livingston to Anniston line.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Activation of storm spotters and emergency management may be needed
on through tonight. Please follow all local, state, and CDC
guidelines in regards to travel.

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 28, 7:24 AM CDTAreal Flood AdvisoryBMXGreene, Hale, Sumter5 hr
Aug 28, 8:13 AM CDTAreal Flood AdvisoryBMXBibb, Greene, Hale, Tuscaloosa3 hr
Aug 28, 10:21 AM CDTFlash Flood WatchBMXBibb, Blount, Calhoun, Cherokee, Chilton, Clay and 13 more49 min
Aug 28, 12:37 PM CDTSpecial Weather StatementBMXTalladega53 min
Aug 28, 12:39 PM CDTSpecial Weather StatementBMXMarengo51 min
Aug 28, 1:15 PM CDTSpecial Weather StatementBMXClay, Talladega45 min
Aug 28, 2:28 PM CDTSpecial Weather StatementBMXMarion47 min
Aug 28, 3:26 PM CDTSpecial Weather StatementBMXWinston49 min
Aug 28, 3:36 PM CDTSevere Thunderstorm WarningBMXMarion39 min
Aug 28, 4:09 PM CDTSpecial Weather StatementBMXElmore36 min
Aug 28, 4:15 PM CDTSpecial Weather StatementBMXMarion, Winston45 min
Aug 28, 4:32 PM CDTSevere Thunderstorm WarningBMXFayette, Lamar, Marion43 min
Aug 28, 4:36 PM CDTTornado WarningBMXWinston39 min
Aug 28, 5:10 PM CDTAreal Flood AdvisoryBMXLamar, Marion, Winston2 hr
Aug 28, 5:14 PM CDTSpecial Weather StatementBMXLee46 min
Aug 28, 5:15 PM CDTSevere Thunderstorm WarningBMXWinston15 min
Aug 28, 5:16 PM CDTSpecial Weather StatementBMXFayette, Lamar, Winston44 min
Aug 28, 5:21 PM CDTSevere Thunderstorm WarningBMXMarion, Walker, Winston54 min
Aug 28, 5:27 PM CDTSevere Thunderstorm WarningBMXFayette, Lamar, Walker43 min

Nearby

Flash Flood Watches in Alabama, 2020Every flash flood watch in 2020

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.