Afternoon temperatures climbing into the lower 90s and a very humid airmass produced heat index values reached 105-108 degrees in north central and northwest Alabama.
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The episode as NWS HUN wrote it up.
Afternoon temperatures climbing into the lower 90s and a very humid airmass produced heat index values reached 105-108 degrees in north central and northwest Alabama.
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 31, 11:33 AM CST, 27 minutes earlier.
Area Forecast Discussion National Weather Service Huntsville AL 1233 PM CDT Sat Jul 31 2021 .UPDATE... For 18Z TAFS. && .NEAR TERM...(Rest of Today) Issued at 934 AM CDT Sat Jul 31 2021 The forecast remains on track for a very hot and humid day across the Tennessee Valley. A Heat Advisory remains in effect through 7 PM for the entire area. Early morning low stratus/fog is quickly dissipating and am expecting a fairly similar repeat of yesterday as temperatures climb to the low to mid 90s and heat index values exceed 105 degrees. Expect most areas will stay within the 105-110 range, but it is not out of the question that a few locations in northwest Alabama may hit warning criteria again. A weak convergence boundary over the area may also serve as a focus for isolated to scattered convection this afternoon. A few storms may become locally strong with gusty winds being the main threat. However, the better forcing will remain to the north and for this reason, think our coverage will likely be less than yesterday. .SHORT TERM...(Tonight through Monday) Issued at 400 AM CDT Sat Jul 31 2021 Attention tonight will turn towards expected convective development in the mid-Miss Valley and its possible impact on our area late Saturday night into Sunday morning. As the upr ridge builds westward into the West CONUS later today, the eastern CONUS trough downstream will begin to amplify. Vorticity maxima along the ridge/trough interface will move SEWRD into the mid-Miss Valley atop a thermal/moisture maximum and sfc front. This will likely lead to rapid convection and perhaps MCS development in this region later this afternoon/evening...which has been a persistent feature in recent regional/global guidance. While there remains a degree of uncertainty regarding the extent and subsequent movement of the MCS/convection, forecast steering flow, low-lvl jet configuration, boundary layer theta-e and other factors suggest the MCS/convection could affect a portion of the area by daybreak Sunday. There could also be slow-movement and backward propagation of cells, which would indicate a heavy rain potential in the moisture-rich environment. Nevertheless, there remains too much uncertainty regarding the evolution of this activity later tonight, so this will bear some watching and fine-tuning of the forecast. Otherwise, on Sunday the upr-lvl trough will begin gradually deepen in the region with associated mid/upr vorticity generating further shower/thunderstorm activity atop the stalled sfc front. A general lack of strong lapse rates and shear will limit overall storm strength/organization. Further amplification of the East CONUS trough will take place on Monday and drier air will begin to filter into the region from the north. Although the main frontal boundary is expected to be just to the south of the region on Monday, a vort max embedded in the southern periphery of the trough will move atop sufficient boundary layer moisture and may generate additional showers/thunderstorms. However, coverage is expected to be somewhat low and will be favored in southern locations, nearest the best moisture. Drier air will gradually filter into the region on Monday, with dew points falling into the low/mid 60s at many spots by afternoon. .LONG TERM...(Monday night through Friday) Issued at 400 AM CDT Sat Jul 31 2021 An amplified mid-level longwave trough will encompass much of central/eastern North America at the beginning of the extended period, with a distinct vort max and related surface cold front expected to cross the region from NW-to-SE on Monday evening. Due to the predicted timing of the front, we have included a low chance POP for showers and a few thunderstorms across our southeastern zones during the evening hours. However, this activity should end rather quickly as a drier airmass (characterized by PWAT values around 1 inch and boundary layer dewpoints in the u50s-m60s) is advected southward. Lows on Tuesday morning in the l-m 60s will be pleasantly cool, and roughly 2-4 degrees below normal for the beginning of August. For the remainder of the week, global models all indicate that cyclonic flow aloft will remain in place across the Eastern CONUS, as the southern portion of the initial longwave trough becomes cutoff from the stronger westerlies to its north. At least a couple of weak disturbances embedded in this flow will shift across the Southeastern CONUS, resulting in weak cyclogenesis along the stalled front well to our south. There are some indications in the model guidance that a trough extending northward from the Gulf Coast region may focus the development of diurnal showers and thunderstorms to our southeast on Wednesday/Thursday/Friday afternoons, and we have included a low chance POP for our eastern zones to reflect uncertainty regarding the position of this feature. However, we generally anticipate a cooler/drier week, with lows in the l-m 60s and highs in the l-m 80s only gradually beginning to increase by Friday. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1233 PM CDT Sat Jul 31 2021 VFR conditions will prevail at each terminal this afternoon and evening as AM low stratus have finally broken up. Late tonight into Sunday, a cold front will increase our prospects for -TSRA/SHRA and have highlighted this accordingly. These storms could cause a reduction in visibilities and ceilings to MVFR levels and have added a PROB30 to cover this. Low clouds and SHRA are then expected to linger into the morning hours on Sunday. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...Heat Advisory until 7 PM CDT this evening for ALZ001>010-016. TN...Heat Advisory until 7 PM CDT this evening for TNZ076-096-097. && NEAR TERM...AMP.24 SHORT TERM...KDW LONG TERM...70/DD AVIATION...AMP.24 For more information please visit our website at weather.gov/huntsville.
Hazardous Weather Outlook National Weather Service Huntsville AL 506 AM CDT Sat Jul 31 2021 ALZ001>010-016-TNZ076-096-097-010030- Lauderdale-Colbert-Franklin AL-Lawrence-Limestone-Madison-Morgan- Marshall-Jackson-DeKalb-Cullman-Moore-Lincoln-Franklin TN- 506 AM CDT Sat Jul 31 2021 This Hazardous Weather Outlook is for north Alabama and portions of southern middle Tennessee. .DAY ONE...Today and Tonight... Dangerous heat is expected across the Tennessee Valley again today, with peak heat index values expected to range from 105 to 110 degrees. A Heat Advisory is in effect for the entire forecast area from 10 AM to 7 PM CDT. Isolated to scattered thunderstorms are expected today, mainly in southwestern portions of the area. Some of these thunderstorms may be capable of producing strong wind gusts. Showers and thunderstorms may affect the area tonight, some of which may be capable of producing strong, gusty winds and locally heavy rainfall. .DAYS TWO THROUGH SEVEN...Sunday through Friday... The best chances for thunderstorms in the region during the outlook period will occur on Sunday, with lesser chances on Monday. Isolated to widely scattered thunderstorms will be possible across mainly the eastern portion of the outlook area each day from Tuesday- Friday. .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.
6 heat. Local standard time, as filed.
During the afternoon, temperatures climbing into the lower 90s and a very humid airmass produced dangerous heat index values ranging from 105 to 109 degrees.
During the afternoon, temperatures climbing into the lower 90s and a very humid airmass produced dangerous heat index values ranging from 105 to 109 degrees.
Temperatures climbing into the lower 90s and a very humid airmass produced heat index values of 105 to 107 degrees.
Temperatures climbing into the lower 90s in the afternoon hours and a humid airmass briefly produced heat index values reaching 105 degrees.
Temperatures climbing into the lower 90s and a very humid airmass produced dangerous heat index values ranging from 105 to 109 degrees.
Temperatures climbing into the lower 90s and a humid airmass briefly produced heat index values of 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: 977056, 977057, 977077, 977054, 977059, 977055.