Showers and thunderstorms repeatedly moved across western portions of Lauderdale and Colbert Counties on the 17th, producing widespread rainfall amounts of 3-6 over a few hours. Heavy rainfall also affected Limestone County, both downtown in Decatur, and north, along the AL/TN border again on the 18th.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS HUN wrote it up.
Showers and thunderstorms repeatedly moved across western portions of Lauderdale and Colbert Counties on the 17th, producing widespread rainfall amounts of 3-6 over a few hours. Heavy rainfall also affected Limestone County, both downtown in Decatur, and north, along the AL/TN border again on the 18th. This led to numerous reports of flooding and flash flooding in and around Cherokee, AL, Ardmore, AL, and in Decatur, AL.
The local office's own words before the first event, 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 the first event at Sep 17, 1:18 PM CST, 3 hours 26 minutes earlier.
Area Forecast Discussion National Weather Service Huntsville AL 218 PM CDT Fri Sep 17 2021 .NEAR TERM...(Tonight) Issued at 215 PM CDT Fri Sep 17 2021 Afternoon surface analysis shows a small circulation associated with the remnants of Nicholas over N. LA. Meanwhile, broader syntopic flow is helping to surge moisture northward into the TN Valley region. The mid/upper level trough to our west is now approaching the ArkLaTex region and helping to propagate some vort maxes east of the MS River. The combination of these features will help maintain the persistent 1-2kft cloud deck and will gradually help to increase shower activity through tonight. Radar trends support the western zones as a focus for activity in the near term, with less coverage in the eastern zones. After midnight, rainfall will diminish across the area, becoming more widely scattered in coverage. .SHORT TERM...(Saturday through Sunday) Issued at 215 PM CDT Fri Sep 17 2021 The wet patterns continues and persistence prevails. As the mid/upper low to our west encroaches further upon the region it will interact moreso with the deep tropical air mass in place. Showers (with a few embedded thunderstorms) will become more widespread heading into the afternoon hours each day, and wane between midnight and sunrise each morning. Even with this wet pattern in place, areal average rainfall totals through the weekend look to remain below 2". Locally higher amounts cannot be ruled out given the potential for brief heavy downpours thanks to the increased PW values. Persistence in the sky forecast prevails as well. Cloudy conditions will limit afternoon highs each day to the upper 70s/low 80s. .LONG TERM...(Sunday night through Thursday) Issued at 215 PM CDT Fri Sep 17 2021 Southwesterly flow throughout much of the atmosphere will feature to start the upcoming work week. Moisture will remain high across the area with PW values around 1.8-1.9 inches. These values are near the 90th percentile for mid to late September. Model soundings indicate a saturated atmosphere with lapse rates near moist adiabatic on Monday. Additionally, there will be a shortwave trough advancing northeastward from the Lower Mississippi River Valley into the Tennessee River Valley. Therefore, expect another day of widespread showers/storms on Monday. With weak lapse rates, only expect embedded thunderstorms at this this point. Highs on Monday will be in the upper 70s to low 80s with widespread cloud cover and precipitation. The shortwave trough will lift out to the north and east Monday night into early Tuesday. The focus will then shift to a more amplified trough moving across the central CONUS on Tuesday. Moisture and PW values will remain elevated ahead of this trough and surface front on Tuesday with elevated PoPs as well. However, do not expect rain to be as widespread or as heavy as Monday. There are still some minor timing issues between the models on the timing of the front that range from late Tuesday into Wednesday. Continued with some PoPs into the day on Wednesday to account for the slower model solutions but these may be removed in later forecast issuances in favor of the faster solutions. The main story for the mid to later part of next week will be the arrival of the fall airmass. Highs Thursday and Friday will generally be in the mid to upper 70s with sunny skies. The coldest morning looks to be Friday morning with temperatures down in the upper 40s to low 50s. This cool and dry airmass looks to continue into next weekend. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) Issued at 1232 PM CDT Fri Sep 17 2021 Moving into the 18Z hour, shower activity is gradually increasing. MVFR cigs are firmly in place and will remain in place through the TAF period. Heading into the overnight hours there may be periods of IFR cigs but confidence in that forecast is low. For rain - given the scattered nature of these small areas of showers (and a couple embedded TS), have kept VCSH at HSV this afternoon but a Tempo for TSRA at MSL where there'll be a chance of a storm. Rain and convection will wane in the overnight, we'll see a return of SHRA after sunrise. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && NEAR TERM...Barron SHORT TERM...Barron LONG TERM...MA AVIATION...Barron For more information please visit our website at weather.gov/huntsville.
Hazardous Weather Outlook National Weather Service Huntsville AL 220 PM CDT Fri Sep 17 2021 ALZ001>010-016-TNZ076-096-097-181030- Lauderdale-Colbert-Franklin AL-Lawrence-Limestone-Madison-Morgan- Marshall-Jackson-DeKalb-Cullman-Moore-Lincoln-Franklin TN- 220 PM CDT Fri Sep 17 2021 This Hazardous Weather Outlook is for north central Alabama, northeast Alabama, northwest Alabama and southern middle Tennessee. .DAY ONE...This afternoon and tonight. Numerous showers with a couple thunderstorms will be possible through tonight. Locally heavy downpours will be the primary threat with the strongest activity. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Numerous to widespread showers and thunderstorms are expected to develop across the region Saturday through Tuesday as an area of low pressure moves across the Deep South. This activity will become more scattered in nature on Wednesday. Locally heavy downpours will be the primary threat with the strongest activity. .SPOTTER INFORMATION STATEMENT... Activation of storm spotters and emergency management personnel is not anticipated at this time.
Special Weather Statement
National Weather Service Huntsville AL
451 PM CDT Fri Sep 17 2021
ALZ001-002-172230-
Lauderdale AL-Colbert AL-
451 PM CDT Fri Sep 17 2021
...A cluster of thunderstorms will impact portions of western
Lauderdale and northwestern Colbert Counties through 530 PM CDT...
At 445 PM CDT, Doppler radar was tracking a cluster of training
thunderstorms producing heavy rainfall extending from the Cherokee
to Waterloo communities. This activity was moving north at 15 mph.
HAZARD...Winds in excess of 40 mph and torrential rainfall.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. One to two inches of rainfall could
produce some ponding and localized flooding in these areas.
Locations impacted include...
Cherokee, Waterloo, Threet, Margerum, Riverton, Wright, Oakland and
Barton.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Do not drive your vehicle through flooded roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
&&
LAT...LON 3501 8812 3501 8772 3500 8770 3470 8785
3477 8811 3489 8810 3491 8814
TIME...MOT...LOC 2145Z 197DEG 15KT 3497 8795
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH
KTWThe Columbus AFB radar (KGWX), 111 km away, was scanning. The volume nearest the first event began at 22:44 UTC.
13 flash flood. Local standard time, as filed.
Flash Flooding reported in the 6900 block of North Pike Road.
Flash flooding reported in the 11000 block of White Pike Road. Depth of water unknown.
Flash Flooding was reported at the intersection of Mt Hester Road and Forrest Drive in Cherokee.
Flash flooding reported at the intersection of Cove Road and Chickasaw Drive.
Flash Flooding was reported at the intersection of 6th and North Pike in Cherokee.
Flash flooding reported at the intersection of Mulberry Lane and Moody Lane in Cherokee.
Flash flooding was reported at the intersection of Old Lee Highway and Barnes Lane in Cherokee.
Flash Flooding was reported at the intersection of North Jackson Highway and E 2nd Street.
Flash flooding reported at the intersection of North Pike and Riverton Rose Trace.
Occupants of a vehicle rescued from a flooded ditch at Park Avenue in Ardmore, AL.
Multiple vehicles submerged in the floodwaters between Ardmore and Elkmont. Depth of water unknown.
Barnes Road washed out in Ardmore, AL.
Lee Street in front of the Courthouse is under water. Parts of Church Street also underwater, affecting businesses. Fire and Police Dept assisting motorists in the area. Depth of water unknown.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Alabama in 2021Every state in 2021This day in weather historyWarnings in Alabama, September 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 987228, 987229, 987230, 987232, 987233, 987234, 987235, 987237, 987239, 987222, 987223, 987224, 987226.