Alert archive / Alabama / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 102, NWS Huntsville, AL

August 27, 2020DeKalb County, Jackson County, Alabama

NWS Huntsville, AL issued this severe thunderstorm warning at Aug 27, 2020, 4:18 PM CDT for DeKalb County, Jackson County, Alabama. It was in force for 27 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Aug 27, 2020, 4:18 PM CDT (21:18 UTC)
Expired
Aug 27, 2020, 4:45 PM CDT
In force
27 min
Issued by
NWS Huntsville, AL
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties DeKalb County, AL, Jackson County, AL

The radar

The Northeast Alabama radar (KHTX), 38 km from the middle of the area, began a volume at 21:19 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, 9.3 hours before the alert went out and 179 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 2020-08-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1075 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 2020-08-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 48 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
1075 J/kg
Mixed-layer CIN
-31 J/kg
Mixed-layer LCL
843 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
48 m²/s²
0-3 km storm-relative helicity
71 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 severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Huntsville, AL wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 27, 3:30 PM CDT, 48 minutes earlier.

Area forecast discussion, Aug 27, 3:30 PM CDT, 48 minutes before
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Hazardous weather outlook, Aug 27, 3:43 AM CDT, 12 hours 35 minutes before
Hazardous Weather Outlook
National Weather Service Huntsville AL
343 AM CDT Thu Aug 27 2020

ALZ001>010-016-TNZ076-096-097-272345-
Lauderdale-Colbert-Franklin AL-Lawrence-Limestone-Madison-Morgan-
Marshall-Jackson-DeKalb-Cullman-Moore-Lincoln-Franklin TN-
343 AM CDT Thu Aug 27 2020

This Hazardous Weather Outlook is for north Alabama and portions of
southern middle Tennessee.

.DAY ONE...Today and Tonight...

Isolated to scattered thunderstorms will be possible today, mainly
during the afternoon and early evening hours.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday...

Thunderstorm coverage will increase Friday into Saturday, as the
remnants of Hurricane Laura move eastward across the Mid South and
lower Ohio Valley areas. A few storms may be capable of producing
locally heavy rainfall and strong gusty winds. A few tornadoes may
also be possible late Friday.

Scattered storms will remain in the forecast Sunday and Monday, as a
weak frontal boundary settles into the region from the north.

.SPOTTER INFORMATION STATEMENT...

Formal activation of storm spotters and emergency management
personnel is not anticipated at this time. However, timely reports
of flooding will be greatly appreciated.

Please relay any information about observed severe weather to the
NWS while following all local, state, and CDC guidelines.

In the hours before

Special weather statement, Aug 27, 3:36 PM CDT, 42 minutes before
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Special weather statement, Aug 27, 3:40 PM CDT, 38 minutes before
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Special weather statement, Aug 27, 3:48 PM CDT, 30 minutes before
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Special weather statement, Aug 27, 3:53 PM CDT, 25 minutes before
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Special weather statement, Aug 27, 3:59 PM CDT, 19 minutes before
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Special weather statement, Aug 27, 4:11 PM CDT, 7 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Aug 27, 3:16 PM CDTSpecial Weather StatementHUNFranklin44 min
Aug 27, 3:21 PM CDTSevere Thunderstorm WarningHUNLimestone, Madison24 min
Aug 27, 3:30 PM CDTSpecial Weather StatementHUNLawrence30 min
Aug 27, 3:36 PM CDTSpecial Weather StatementHUNFranklin24 min
Aug 27, 3:40 PM CDTSpecial Weather StatementHUNLawrence50 min
Aug 27, 3:53 PM CDTSpecial Weather StatementHUNDeKalb37 min
Aug 27, 3:59 PM CDTSpecial Weather StatementHUNColbert, Lauderdale31 min
Aug 27, 4:11 PM CDTSpecial Weather StatementHUNDeKalb, Jackson49 min
Aug 27, 4:27 PM CDTSpecial Weather StatementHUNLimestone33 min
Aug 27, 4:30 PM CDTSpecial Weather StatementHUNLauderdale30 min
Aug 27, 4:58 PM CDTSpecial Weather StatementHUNJackson47 min
Aug 27, 5:04 PM CDTSevere Thunderstorm WarningHUNJackson26 min
Aug 27, 6:12 PM CDTSpecial Weather StatementHUNMadison33 min
Aug 27, 6:26 PM CDTSpecial Weather StatementHUNMadison49 min
Aug 27, 5:32 PM CDTSpecial Weather StatementHUNFranklin28 min
Aug 27, 5:52 PM CDTSpecial Weather StatementHUNFranklin38 min

Nearby

Severe Thunderstorm Warnings in Alabama, 2020Every severe thunderstorm warning 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.