Alert archive / Alabama / Areal Flood Advisories in 2021

Areal Flood Advisory 71, NWS Birmingham, AL

July 18, 2021Marengo County, Alabama

NWS Birmingham, AL issued this areal flood advisory at Jul 18, 2021, 4:45 PM CDT for Marengo County, Alabama. It was in force for 2 hr.

The area

The counties it named.

The facts

Issued: Jul 18, 2021, 4:45 PM CDT (21:45 UTC)
Expired: Jul 18, 2021, 6:45 PM CDT
In force: 2 hr
Issued by: NWS Birmingham, AL
Area: Storm-based polygon

County Marengo County, AL

The radar

The Birmingham radar (KBMX), 140 km from the middle of the area, began a volume at 21:45 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

Jackson, MS (KJAN), launched 12:00Z, 9.8 hours before the alert went out and 216 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: 505 J/kg
Mixed-layer CIN: -58 J/kg
Mixed-layer LCL: 870 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 43 m²/s²
0-3 km storm-relative helicity: 48 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this areal flood advisory 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 areal flood advisory went out at Jul 18, 2:47 PM CDT, 1 hour 58 minutes earlier.

Area forecast discussion, Jul 18, 2:47 PM CDT, 1 hour 58 minutes before

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Hazardous weather outlook, Jul 18, 4:09 AM CDT, 12 hours 36 minutes before

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In the hours before

Special weather statement, Jul 18, 4:07 PM CDT, 38 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 18, 3:34 PM CDT	Areal Flood Advisory	BMX	Lowndes	116 min
Jul 18, 3:48 PM CDT	Areal Flood Advisory	BMX	Marengo, Perry	117 min
Jul 18, 4:07 PM CDT	Special Weather Statement	BMX	Marengo	38 min

Nearby

Areal Flood Advisories in Alabama, 2021 Every areal flood advisory 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.