Alert archive / Alabama / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 82, NWS Huntsville, AL

July 21, 2020Lawrence County, Alabama

NWS Huntsville, AL issued this severe thunderstorm warning at Jul 21, 2020, 5:11 PM CDT for Lawrence County, Alabama. It was in force for 34 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
Jul 21, 2020, 5:11 PM CDT (22:11 UTC)
Expired
Jul 21, 2020, 5:45 PM CDT
In force
34 min
Issued by
NWS Huntsville, AL
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

County Lawrence County, AL

The radar

The Columbus AFB radar (KGWX), 117 km from the middle of the area, began a volume at 22:14 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, 10.2 hours before the alert went out and 190 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 2020-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 234 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 2020-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -8 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
234 J/kg
Mixed-layer CIN
-158 J/kg
Mixed-layer LCL
1394 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
-8 m²/s²
0-3 km storm-relative helicity
16 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 Jul 21, 2:37 PM CDT, 2 hours 34 minutes earlier.

Area forecast discussion, Jul 21, 2:37 PM CDT, 2 hours 34 minutes before
Area Forecast Discussion
National Weather Service Huntsville AL
237 PM CDT Tue Jul 21 2020

.NEAR TERM...(Tonight)
Issued at 237 PM CDT Tue Jul 21 2020

Latest water vapor imagery shows a trough over the Mid and Upper
Mississippi Valleys, with ridging over the western CONUS and anchored
over the southeast. The TN Valley remains on the periphery of these
features, with seasonably warm conditions. Area radars show isolated
showers and thunderstorms over the area, with activity initiating
along outflow boundaries. This trend should continue over the next
few hours, as daytime heating aids in the focus for convection. Much
like yesterday, some storms may become strong and produce gusty
winds. This activity will quickly dissipate around sunset, leaving
seasonably mild conditions overnight. With decent radiational
cooling once again tonight, lows will fall into the lower 70s by
daybreak.

.SHORT TERM...(Wednesday through Thursday night)
Issued at 237 PM CDT Tue Jul 21 2020

The shortwave trough over the Mississippi Valley will weaken and move
eastward on Wednesday while the ridge over the southeast retreats to
the south. Moisture over the TN Valley will remain abundant, as PW
values climb to near 2 inches. With less subsidence over the area on
Wednesday, we will likely see a greater coverage of convection that
observed today and yesterday. However, while blended guidances paints
60-70% PoPs tomorrow afternoon, confidence is not high enough to keep
this in the forecast. Thus, PoPs were maxed at around 50%. A weak
frontal boundary will sag southward on Thursday, and attempt to reach
the TN Valley. However, with some influence from the ridge still over
the area, along with the incredibly moist airmass, this boundary will
likely stall to our north before dissipating. Nonetheless, our
northeastern counties may see numerous storms on Thursday afternoon.
As with any day in the summer, these storms will be unorganized and
pose a threat for gusty winds up to 50 mph.

Temps will generally remain near normal through the short term
period, except for areas that receive rainfall. Highs will warm into
the upper 80s to lower 90s, with overnight is the lower 70s.

.LONG TERM...(Thursday night through Monday)
Issued at 237 PM CDT Tue Jul 21 2020

Mid level ridging over the Plains will build eastward during the
long term period. This will lead to warming temperatures and lowering
chances for showers and thunderstorms. Latest guidance suggest that
the TN Valley will remain on the eastern periphery of the ridge,
keeping flow aloft more northerly. This will set the stage for
potential shortwaves to move southward over the area and provide an
enhancement to our diurnally drive convection. It's too soon to
really say what, if any, of these disturbances makes their way into
the area so we will maintain scattered showers and thunderstorms
each afternoon. Temps through the long term will almost be a rise and
repeat each day with highs in the upper 80s/lower 90s and lows in
the lower 70s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1239 PM CDT Tue Jul 21 2020

Scattered showers and thunderstorms are expected to develop
throughout the afternoon, and some may be in the vicinity of terminals.
Winds will generally be light and variable, barring any gusts from
proximity thunderstorms. If thunderstorms become more numerous in the
vicinity of the airport, amendments may be necessary. Localized fog
development is possible closer to daybreak, but is not expected to
affect visibility at the terminals.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

NEAR TERM...73
SHORT TERM...73
LONG TERM...73
AVIATION...LH

For more information please visit our website
at weather.gov/huntsville.
Hazardous weather outlook, Jul 21, 2:40 PM CDT, 2 hours 31 minutes before
Hazardous Weather Outlook
National Weather Service Huntsville AL
240 PM CDT Tue Jul 21 2020

ALZ001>010-016-TNZ076-096-097-221045-
Lauderdale-Colbert-Franklin AL-Lawrence-Limestone-Madison-Morgan-
Marshall-Jackson-DeKalb-Cullman-Moore-Lincoln-Franklin TN-
240 PM CDT Tue Jul 21 2020

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

.DAY ONE...Tonight...

Scattered thunderstorms are possible this afternoon and evening with
the primary threats posed by any stronger storms being lightning,
gusty winds, and brief heavy rainfall.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday...

Thunderstorms will increase in coverage again on Wednesday and
continue through at least Friday. Some of these thunderstorms during
this time period may be capable of producing strong gusty winds and
locally heavy rainfall. Thunderstorm chances will continue through
the weekend into early next week.

.SPOTTER INFORMATION STATEMENT...

Activation of storm spotters and emergency management personnel is
not anticipated at this time.

In the hours before

Special weather statement, Jul 21, 3:36 PM CDT, 1 hour 35 minutes before
Special Weather Statement
National Weather Service Huntsville AL
336 PM CDT Tue Jul 21 2020

ALZ008-010-212045-
Marshall AL-DeKalb AL-
336 PM CDT Tue Jul 21 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN MARSHALL AND
SOUTHWESTERN DEKALB COUNTIES UNTIL 345 PM CDT...

At 335 PM CDT, Doppler radar was tracking a strong thunderstorm 8
miles northwest of Geraldine, moving north at 10 mph. Dime size hail
and winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Guntersville and Lake Guntersville St Park.

LAT...LON 3441 8606 3434 8610 3434 8626 3451 8621
TIME...MOT...LOC 2035Z 176DEG 8KT 3441 8613

KTW
Special weather statement, Jul 21, 3:54 PM CDT, 1 hour 17 minutes before
Special Weather Statement
National Weather Service Huntsville AL
354 PM CDT Tue Jul 21 2020

ALZ004-007-016-212130-
Lawrence AL-Morgan AL-Cullman AL-
354 PM CDT Tue Jul 21 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN CULLMAN...
SOUTHWESTERN MORGAN AND SOUTHEASTERN LAWRENCE COUNTIES UNTIL 430 PM
CDT...

At 354 PM CDT, Doppler radar was tracking a strong thunderstorm near
Cullman, moving northwest at 20 mph.

Winds in excess of 30 mph will be possible with this storm.

Locations impacted include...
Cullman, Good Hope, Baldwin, Vinemont, West Point, Speake,
Battleground, Lacon, Logan and Jones Chapel.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Very heavy rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike several miles away from a thunderstorm. Seek a
safe shelter inside a building or vehicle.

&&

LAT...LON 3416 8711 3430 8711 3430 8735 3452 8712
      3423 8675 3408 8691
TIME...MOT...LOC 2054Z 118DEG 18KT 3424 8690

KTW
Special weather statement, Jul 21, 4:21 PM CDT, 50 minutes before
Special Weather Statement
National Weather Service Huntsville AL
421 PM CDT Tue Jul 21 2020

ALZ003-212145-
Franklin AL-
421 PM CDT Tue Jul 21 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN FRANKLIN COUNTY
UNTIL 445 PM CDT...

At 420 PM CDT, Doppler radar was tracking a cluster of strong
thunderstorms 7 miles west of Hackleburg. These storms were moving
slowly north around 5 mph.

Wind gusts up to 50 mph will be possible with this storm.

Locations impacted include...
Red Bay, Belgreen, Vina, Hodges, Atwood, Little Bear Creek Reservoir,
Halltown and Duketon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Very heavy rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike several miles away from a thunderstorm. Seek a
safe shelter inside a building or vehicle.

&&

LAT...LON 3444 8816 3450 8784 3431 8783 3431 8795
      3432 8796 3431 8805 3432 8817
TIME...MOT...LOC 2120Z 355DEG 4KT 3430 8797

KTW
Special weather statement, Jul 21, 4:28 PM CDT, 43 minutes before
Special Weather Statement
National Weather Service Huntsville AL
428 PM CDT Tue Jul 21 2020

ALZ004-016-212215-
Lawrence AL-Cullman AL-
428 PM CDT Tue Jul 21 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN CULLMAN AND
SOUTHEASTERN LAWRENCE COUNTIES UNTIL 515 PM CDT...

At 428 PM CDT, Doppler radar was tracking a strong thunderstorm over
Inmanfield, moving west at 10 mph.

Dime size hail will be possible with this storm.

Locations impacted include...
Wren and Bankhead National Forest.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike several miles away from a thunderstorm. Seek a
safe shelter inside a building or vehicle.

&&

LAT...LON 3430 8711 3430 8739 3447 8728 3434 8711
      3431 8711 3431 8708 3430 8706 3426 8711
TIME...MOT...LOC 2128Z 100DEG 8KT 3429 8719

KTW
Special weather statement, Jul 21, 4:37 PM CDT, 34 minutes before
Special Weather Statement
National Weather Service Huntsville AL
437 PM CDT Tue Jul 21 2020

ALZ004-007-212200-
Lawrence AL-Morgan AL-
437 PM CDT Tue Jul 21 2020

...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL MORGAN AND EAST
CENTRAL LAWRENCE COUNTIES UNTIL 500 PM CDT...

At 437 PM CDT, Doppler radar was tracking a strong thunderstorm 7
miles west of Hartselle, moving northwest at 10 mph.

Dime size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Decatur, Hartselle, Trinity, Neel and Caddo.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Very heavy rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike several miles away from a thunderstorm. Seek a
safe shelter inside a building or vehicle.

&&

LAT...LON 3442 8695 3436 8709 3449 8726 3465 8714
TIME...MOT...LOC 2137Z 130DEG 7KT 3443 8707

KTW
Special weather statement, Jul 21, 4:55 PM CDT, 16 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Jul 21, 1:12 PM CDTSpecial Weather StatementHUNJackson48 min
Jul 21, 2:25 PM CDTSpecial Weather StatementHUNJackson50 min
Jul 21, 3:07 PM CDTSpecial Weather StatementHUNMadison8 min
Jul 21, 3:22 PM CDTSpecial Weather StatementHUNCullman23 min
Jul 21, 3:36 PM CDTSpecial Weather StatementHUNMarshall9 min
Jul 21, 3:38 PM CDTSevere Thunderstorm WarningHUNMarshall19 min
Jul 21, 3:54 PM CDTSpecial Weather StatementHUNCullman36 min
Jul 21, 4:21 PM CDTSpecial Weather StatementHUNFranklin24 min
Jul 21, 4:28 PM CDTSpecial Weather StatementHUNLawrence47 min
Jul 21, 4:37 PM CDTSpecial Weather StatementHUNLawrence23 min
Jul 21, 4:48 PM CDTSevere Thunderstorm WarningHUNFranklin27 min
Jul 21, 4:55 PM CDTSpecial Weather StatementHUNLawrence35 min
Jul 21, 5:16 PM CDTSpecial Weather StatementHUNMadison29 min
Jul 21, 5:21 PM CDTSpecial Weather StatementHUNDeKalb39 min
Jul 21, 5:29 PM CDTSpecial Weather StatementHUNMadison46 min
Jul 21, 5:32 PM CDTSevere Thunderstorm WarningHUNDeKalb28 min
Jul 21, 5:36 PM CDTSpecial Weather StatementHUNColbert39 min
Jul 21, 5:42 PM CDTSpecial Weather StatementHUNDeKalb48 min
Jul 21, 5:51 PM CDTSpecial Weather StatementHUNMadison39 min
Jul 21, 5:56 PM CDTSevere Thunderstorm WarningHUNDeKalb34 min
Jul 21, 6:08 PM CDTSpecial Weather StatementHUNLauderdale52 min
Jul 21, 6:21 PM CDTSpecial Weather StatementHUNDeKalb9 min
Jul 21, 6:40 PM CDTSpecial Weather StatementHUNJackson35 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.