Alert archive / Alabama / Mesoscale Discussions in 2020

Mesoscale Discussion 1365

July 31, 202016 counties in Alabama; Chattooga County, Dade County, Walker County, Georgia

The Storm Prediction Center issued this mesoscale discussion at Jul 31, 2020, 1:29 PM CDT for 16 counties in Alabama; Chattooga County, Dade County, Walker County, Georgia. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued
Jul 31, 2020, 1:29 PM CDT (18:29 UTC)
Expired
Jul 31, 2020, 3:00 PM CDT
In force
91 min
Issued by
the Storm Prediction Center
Concerning
Severe potential...watch unlikely
Chance of a watch
20%

Counties Blount County, AL, Calhoun County, AL, Cherokee County, AL, Cullman County, AL, DeKalb County, AL, Etowah County, AL, Fayette County, AL, Jackson County, AL, Jefferson County, AL, Limestone County, AL, Madison County, AL, Marshall County, AL, Morgan County, AL, St. Clair County, AL, Walker County, AL, Winston County, AL, Chattooga County, GA, Dade County, GA, Walker County, GA

The radar

The Birmingham radar (KBMX), 104 km from the middle of the area, began a volume at 18:32 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, 6.5 hours before the alert went out and 103 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 2020-07-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 922 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 2020-07-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 137 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
922 J/kg
Mixed-layer CIN
-50 J/kg
Mixed-layer LCL
835 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
137 m²/s²
0-3 km storm-relative helicity
131 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.4

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 31, 5:23 PM CDTMesoscale DiscussionSPCBlount, Calhoun, Cullman, Etowah, Fayette, Jefferson and 10 more2 hr

Nearby

Mesoscale Discussions in Alabama, 2020Mesoscale Discussions in Georgia, 2020Every mesoscale discussion 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.