Thunderstorms trained across the city of Decatur, AL for several hours on the evening of the 18th into the 19th. Decatur is notorious for flash flooding, with scattered reports occurring in the wake of 3-5 of rainfall in a couple of hours.
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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.
Thunderstorms trained across the city of Decatur, AL for several hours on the evening of the 18th into the 19th. Decatur is notorious for flash flooding, with scattered reports occurring in the wake of 3-5 of rainfall in a couple of hours.
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 Jul 18, 9:26 AM CST, 1 hour 43 minutes earlier.
Area Forecast Discussion National Weather Service Huntsville AL 1026 AM CDT Sun Jul 18 2021 .NEAR TERM...(Rest of Today) Issued at 1026 AM CDT Sun Jul 18 2021 An interesting weekend so far, with another day starting off with extensive stratus coverage. The low clouds this morning covered a good chunk of the CONUS, extending SE from the Central Plains to MO/AR, then eastward across much of the Ohio/Tennessee Valleys to the Mid Atlantic. A closer in view indicated the stratocumulus pretty much covered all of the forecast area. About half of the sites reported Instrument Flight Rules - IFR with cloud bases below 1000 ft AGL, and the other half Marginal Visual Flight Rules 1000-3000 ft AGL. A visible view also indicted the clouds were slowly going from a stratus to cumulus type on a slower rate than yesterday. With the cloud cover, area temperatures were "only" in the 70s with SE-SW winds of 5-10 mph. Unlike yesterday, a local and regional radar view indicated more light showers slowly moving ENE across parts the Tennessee Valley. An area of more numerous and organized convection was heading eastward from western Tennessee to central Mississippi. The models as was the case yesterday have different solutions on what will occur with the TN/MS convection. Some have it fading as it nears the MS/AL border, others have it reaching the area in the early afternoon. In any case, with the stratus becoming cumulus/TCU into the afternoon, more shower and thunderstorm development likely this afternoon and especially in the overnight. The on-going forecast has a good handle with precip chances, so will stay on a higher side of guidance. Given more extensive cloud cover, have cooled the warmer temperatures in the high-T grid a couple of degrees. Also updated QPF grids to more recent guidance. Some areas of the forecast area can absorb 1.5 - 2 inches in one hour per Flash Flood guidance. Given slow storm motion and heavy rainfall output, flooding concerns could increase across the area this afternoon and tonight. .SHORT TERM...(Tonight through Tuesday) Issued at 359 AM CDT Sun Jul 18 2021 This activity should continue into the evening hours, before the atmosphere becomes worked over and lingering rainfall should become lighter. Kept high pops in the forecast though given such a moist airmass and the front possibly draped over or just north of the area. Slightly drier air might push in behind the shortwave, dropping lows into the upper 60s to around 71 degrees. Monday doesn't look very different, as the main front slowly settles southward into northern or central Alabama. Another stronger shortwave is progged by models to move east across the front at the same time. This should produce another round of heavier rainfall over northern Alabama. Again, same ingredients in place..high PWATS, and decent instability. Will have to watch for flooding concerns again, though they may be a bit more widespread. A flash flood watch may be needed for Monday, but holding off for now. This may be the coolest day of the forecast period, with highs only reaching the upper 70s to around 82 degrees in most locations. By Monday night into Tuesday, models are in disagreement concerning how far south the front actually moves. Some show it near Birmingham, while others have it extending southwest from southern middle Tennessee in central Mississippi. Either way, strong upper level lift around 500 mb with the main trough axis should produce post frontal rainfall that could be locally heavy again. Clouds and precipitation should keep highs cool, only reaching the 80 to 85 degree range. .LONG TERM...(Tuesday night through Saturday) Issued at 359 AM CDT Sun Jul 18 2021 Finally by Tuesday night into Wednesday, models seem to really weaken the front and push it into central Georgia and Alabama. This should allow precipitation chances to drop off to isolated to scattered variety. This will bring warmer temperatures (highs 85 to 90 degrees) back into the area through Thursday. Models hint that the decaying front to our south will move back to the north again Thursday night into next weekend, bringing higher rain and storm chances back into the region. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) Issued at 602 AM CDT Sun Jul 18 2021 Currently IFR CIGS just below 1000 feet are firmly in place at both terminals. These should continue (though some brief oscillations to MVFR could occur though 16Z). Expect CIGS to become predominantly VFR though around 18Z at both TAF sites. VCSH look possible near the terminals by then and included a tempo group for TSRA between 18Z and 22Z for possible thunderstorm development when CIGS or VSBYS could drop to MVFR or IFR at times. Though CIGS should rise after 00Z, MVFR VSBYS due to -RA or patchy fog are expected through 6Z. VSBYS look to lower into the IFR realm after 6Z due to fog development with continued light winds. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && NEAR TERM...RSB SHORT TERM...KTW LONG TERM...KTW AVIATION...KTW For more information please visit our website at weather.gov/huntsville.
Hazardous Weather Outlook National Weather Service Huntsville AL 409 AM CDT Sun Jul 18 2021 ALZ001>010-016-TNZ076-096-097-182245- Lauderdale-Colbert-Franklin AL-Lawrence-Limestone-Madison-Morgan- Marshall-Jackson-DeKalb-Cullman-Moore-Lincoln-Franklin TN- 409 AM CDT Sun Jul 18 2021 This Hazardous Weather Outlook is for north Alabama and portions of southern middle Tennessee. .DAY ONE...Today and Tonight... The probability for widespread hazardous weather is low. Showers and scattered thunderstorms are expected to move into northwestern Alabama this morning and push east through the day. Occasional cloud to ground lightning strikes and locally heavy rainfall will be the main threats with the storms. .DAYS TWO THROUGH SEVEN...Monday through Saturday... Numerous showers and scattered storms are forecast on Monday as well, as a front moves south into the area. Frequent cloud to ground lightning and locally heavy rainfall will be the main threats with this activity. This could produce some more widespread flooding concerns. Isolated to scattered chances of showers and storms will continue through Saturday. .SPOTTER CALL TO ACTION STATEMENT... Activation of storm spotters and emergency management personnel is not anticipated at this time. 20
The Northeast Alabama radar (KHTX), 89 km away, was scanning. The volume nearest the first event began at 17:11 UTC.
2 flash flood. Local standard time, as filed.
Flooding reported at the intersection of Church and 6th Avenue in Decatur.
Flooding reported at the intersection of Woodall Road and Highway 20.
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, July 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: 969289, 969290.