As late morning and afternoon temperatures climbed into the lower 90s, a frontal boundary moved into portions of northwestern and north central Alabama. This produced extremely humid conditions and heat index values of 105 to 109 degrees.
Every event with a place to put it; 8 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
As late morning and afternoon temperatures climbed into the lower 90s, a frontal boundary moved into portions of northwestern and north central Alabama. This produced extremely humid conditions and heat index values of 105 to 109 degrees.
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 30, 9:22 AM CST, 1 hour 38 minutes earlier.
Area Forecast Discussion National Weather Service Huntsville AL 1022 AM CDT Fri Jul 30 2021 .NEAR TERM...(Rest of Today) Issued at 1022 AM CDT Fri Jul 30 2021 Another hot and humid day is in store for the Tennessee Valley, as an H5 ridge/high centers over the Central Plains and an upper trough begins to dig over the Southern Appalachians. High cirrus has been evident resulting from a decaying thunderstorm complex that moved across the OH River Valley overnight, and has helped keep temperatures a little cooler than recent mornings so far. A weak upper disturbance will push south through the area today, bringing deeper moisture into the area. Unlike the past few days, this will result in increased chances for showers and thunderstorms later this afternoon. Because of the increase in cloud cover and uncertainty tied to thunderstorm coverage later this afternoon, did not feel confident enough to raise temperatures any today. Even with these limiting factors in mind, there is still a chance some areas could see enough clearing for sufficient diurnal heating and combined with an airmass rich in moisture, afternoon heat indices could reach 105+ in some areas. For that reason, the Heat Advisory is warranted for areas along and west of I-65 through 7PM this evening. .SHORT TERM...(Tonight through Sunday) Issued at 430 AM CDT Fri Jul 30 2021 The ridge will tend to become increasingly elongated W-E on Saturday and warm low-lvl air will continue to be swept into the area in WNW flow. Even behind the sfc front, temperatures will likely not budge much as it essentially washes out just to our south. In fact, moist advection in the low/mid levels will gradually push PW values higher. However, a lack of overall dynamic forcing will limit convective potential on Saturday. With 850 mb temps at levels near today and with a better chance for better insolation and less shower activity...temperatures on Saturday could actually be warmer than today. Increased amplification of the upr flow pattern will begin to take place late Saturday into early Sunday, with a deepening trough developing in the East CONUS. Strengthening low/mid level flow and moisture advection in the Mid-Miss Valley may give rise to an MCS as vorticity moves along the western flank of the trough through the area. This feature may affect portions of our area by Sunday morning and could produce strong wind gusts...but this will need to be watched in future forecasts as its location of development and movement are not certain. Otherwise, the vorticity maximum will move SEWRD while a sfc boundary will be aligned generally W-E in the area and numerous showers and thunderstorms are anticipated for Sunday. Deep layer shear along with low-lvl lapse rates will be more supportive of storm organization and strong updrafts/downdrafts, especially during the late morning/afternoon. .LONG TERM...(Sunday night through Thursday) Issued at 430 AM CDT Fri Jul 30 2021 A consensus solution from the latest suite of global deterministic and ensemble models suggests that a mid-level longwave trough will be in place across the eastern half of North America at the beginning of the extended period. The broader trough is predicted to gradually become more amplified on Sunday night/Monday as a pronounced vort max digs southeastward from the Central Plains into the TN Valley, and lift from this feature will likely contribute to regeneration of showers/thunderstorms along a cold front dropping southward through the forecast area. Due to some uncertainty regarding lingering impacts from thunderstorms during the day on Sunday, as well as the speed/location of the cold front, we have kept POPs in the chance range (highest south of the TN River). Lows on Monday morning will be in the mid 60s-around 70 degree range, with highs later in the day in the l-m 80s. It is becoming increasingly apparent that by Monday night, light- moderate northerly flow in the boundary layer will finally begin to advect a noticeably cooler/drier airmass southward into the region. This trend will persist for the remainder of the long term period, as another vort max to our north evolves into a partially closed low and drifts slowly eastward through the OH Valley. Lows will fall into the m-u 60s Tuesday morning, and l-m 60s Wednesday/Thursday mornings, with highs remaining in the l-m 80s. Regarding precipitation chances, a weak disturbance crossing the region on Tuesday could provide enough lift for a few postfrontal showers during the day, with only a slight chance of showers in our eastern areas on Wednesday/Thursday afternoons. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) Issued at 645 AM CDT Fri Jul 30 2021 Patchy fog is present over the area, although the extent is difficult to discern due to a canopy of high cirrus clouds atop the area. Nevertheless, obs have indicated the presence of fog, even reaching 1/4 SM vis briefly at KMSL earlier ~10Z. The fog will gradually dissipate at terminals by ~13Z. SHRA/TSRA are expected to develop later this morning into the aftn, with best chances in NE AL. Although there is still uncertainty in the extent of coverage today. Nevertheless, confidence supports VCSH in TAFs by 20Z, and PROB30 group is warranted due to sctd nature of expected TSRA activity. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...Heat Advisory until 7 PM CDT this evening for ALZ001>007-016. TN...Heat Advisory until 7 PM CDT this evening for TNZ076-096. && NEAR TERM...25 SHORT TERM...KDW LONG TERM...70/DD AVIATION...KDW For more information please visit our website at weather.gov/huntsville.
Hazardous Weather Outlook National Weather Service Huntsville AL 519 AM CDT Fri Jul 30 2021 ALZ001>010-016-TNZ076-096-097-310030- Lauderdale-Colbert-Franklin AL-Lawrence-Limestone-Madison-Morgan- Marshall-Jackson-DeKalb-Cullman-Moore-Lincoln-Franklin TN- 519 AM CDT Fri Jul 30 2021 This Hazardous Weather Outlook is for north Alabama and portions of southern middle Tennessee. .DAY ONE...Today and Tonight... Isolated to scattered thunderstorms are expected to develop today with best chances for activity in southern Middle Tennessee and northeastern Alabama. A few storms may be capable of producing strong wind gusts. Heat index values are expected to climb to 105 to 107 in portions of northwestern and north central Alabama and in Lincoln and Moore Counties in Tennessee this afternoon. .DAYS TWO THROUGH SEVEN...Saturday through Thursday... A few strong to marginally severe thunderstorms capable of damaging wind gusts and locally heavy rainfall are possible late Saturday night into Sunday. The coverage of thunderstorms will remain fairly high on Sunday night and Monday, before diminishing on Monday night as a cold front crosses the region. Nonetheless, a few thunderstorms will be possible in the eastern portion of the outlook area through Thursday. .SPOTTER CALL TO ACTION STATEMENT... Activation of storm spotters and emergency management personnel is not anticipated at this time.
The national radar mosaic for the moment the first event began.
8 heat. Local standard time, as filed.
During the afternoon hours, temperatures climbing into the mid to upper 90s and very moist conditions produced heat index values of 105 to 109 degrees.
During the afternoon hours, temperatures climbing into the mid to upper 90s and very moist conditions produced dangerous heat index values of 105 to 109 degrees.
During the late morning and afternoon hours, temperatures climbed into the lower 90s as very humid conditions developed producing heat index values of 105 to 108 degrees.
During the afternoon hours, temperatures climbing into the lower 90s and a very humid airmass produced heat index values of 105 to 107 degrees.
During the afternoon hours, temperatures climbing into the lower 90s and a very moist airmass produced dangerous heat index values of 105 to 107 degrees.
During the afternoon hours, temperatures climbing into the lower 90s and a very humid airmass produced heat index values of 105 to 109 degrees.
During the afternoon hours temperatures climbing into the lower to mid 90s and a very humid airmass produced dangerous heat index values from 105 to 109 degrees.
Temperatures climbing the lower 90s during the mid-afternoon hours and a humid airmass produced a brief period of heat index values reaching 105 degrees.
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: 976635, 976636, 976634, 976637, 976638, 977048, 977047, 976640.