Alert archive / Alabama / Mesoscale Discussions in 2020

Mesoscale Discussion 1722

September 28, 202016 counties in Alabama

The Storm Prediction Center issued this mesoscale discussion at Sep 28, 2020, 2:56 PM CDT for 16 counties in Alabama. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Sep 28, 2020, 2:56 PM CDT (19:56 UTC)
Expired
Sep 28, 2020, 5:00 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Concerning
Severe potential...watch unlikely
Chance of a watch
5%

Counties Bibb County, AL, Blount County, AL, Cullman County, AL, Greene County, AL, Hale County, AL, Jackson County, AL, Jefferson County, AL, Madison County, AL, Marengo County, AL, Marshall County, AL, Morgan County, AL, Perry County, AL, Shelby County, AL, Sumter County, AL, Tuscaloosa County, AL, Walker County, AL

The radar

The Birmingham radar (KBMX), 59 km from the middle of the area, began a volume at 20:01 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

Nashville Metro, TN (KBNA), launched 12:00Z, 7.9 hours before the alert went out and 282 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, Nashville Metro, TN at 12:00Z on 2020-09-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 103 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, Nashville Metro, TN at 12:00Z on 2020-09-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 151 square meters per square second.19395878Sfc1 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
103 J/kg
Mixed-layer CIN
-30 J/kg
Mixed-layer LCL
786 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
151 m²/s²
0-3 km storm-relative helicity
142 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

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Nearby

Mesoscale Discussions in Alabama, 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.