textproduct: NWS Birmingham

KEY MESSAGES

Issued at 137 PM CDT WED AUG 19 2026

- Heat: Major HeatRisk is expected to persist through the end of the workweek, with heat indices are forecast between 103 to 108 degrees. A Heat Advisory is now in effect for portions of central Alabama through Thursday

- Thunderstorms: Scattered to isolated afternoon thunderstorms will remain in the forecast through Saturday. Rain chances will increase this weekend.

- Severe: Isolated severe thunderstorms are possible today and Thursday with damaging wind the main threat. The greatest chances for severe thunderstorms will be in the western part of the state today, and the entire state on Thursday.

DISCUSSION

(This afternoon through Tuesday) Issued at 137 PM CDT WED AUG 19 2026

Today, high pressure will remain to the south and west of the area, with flow over the state out of the northwest. A shortwave moving around the high will cause enough lift for scattered to isolated showers and thunderstorms through the late afternoon and evening. Instability is decent, with DCAPE values between 1300 and 1500 J/kg. Steep low level lapse rates, drier air in the mid levels, and weak winds will all contribute to a threat for evaporative cooling aloft and dense cold air providing downdraft/microburst potential in any stronger storm. These parameters are strongest in the western part of the state, and with that shortwave, would keep most of the severe threat west of I65...though there is enough heating for isolated activity to develop along and just east of the I65 through the afternoon and weaken after sunset. Heat indices will remain around 105 degrees or slightly higher, so will keep the Heat Advisory going through tonight.

Tonight, a low pressure over the Great Lakes will move to the northeast, with a frontal boundary around this low slowly moving south through the TN River Valley and into the northern part of the state Thursday afternoon. There should be enough lift and instability for scattered showers and thunderstorms through the afternoon Thursday and Thursday evening, weakening through the early night. Parameters will be similar to Wednesday, though coverage should be higher with the focus of that boundary allowing scattered to more widespread activity. DCAPE remains around 1500 J/kg with several thousand CAPE, weak winds through the atmosphere and dry air in the midlevels. Damaging winds will remain the main threat, with the most likely mode from downburst winds after a storm collapses. With high moisture and warm temperatures remaining, the Heat Advisory will continue through Thursday night. Low temperatures at night in the 70s will exacerbate the effects of heat.

By Friday, a trough east of the MS River will begin to deepen, with flow over the state slowly transitioning to out of the northwest and then west around this trough. The boundary that moved into the north part of the state Thursday will continue to move southward through the state, initiating diurnal convection through the afternoon. Exact placement of where the focus of storms will develop is dependent on that boundary, with the most likely area between the I20 and I85 corridors. Parameters will be similar to the those today and Thursday, with the chance for downburst winds. Temperatures will be a couple of degrees lower on Friday, though moisture should still remain high. Heat indices will be in the triple digits for much of the area, with many places currently forecast to reach the Heat Advisory criteria around 105 degrees.

Saturday, there is uncertainty with the models how far the boundary moves through the area. A few models show scattered to widespread convection through the afternoon, with the boundary and diurnal influences. More recent runs are showing the trough moving into the state and northwest flow prevailing. A weak mid level jet moving around this low could increase winds, especially across the northern half of the area, gusting to 20-25 mph at times through the afternoon. For now, will leave rain in the forecast until more consistent model runs come in. With northwest flow and cooler air advected into the state, the temperatures should be several degrees cooler for Saturday and Sunday, with heat indices for the first time in a week below 105 degrees, though still in the triple digits.

High pressure moves back across the area briefly as a low pressure develops and moves to the east across the AR/TN area. This low will bring an increase in rain chances towards the end of the extended. There is some uncertainty as to how quickly the trough moves to the east and the low moves behind, and will adjust as needed.

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AVIATION

(18Z TAFS) Issued at 137 PM CDT WED AUG 19 2026

Scattered to isolated convection is expected through the afternoon and evening today. The coverage should be greater in the west and southwest, so left mention out of every TAF except KTCL. Otherwise, northerly flow and high pressure will keep VFR conditions at each TAF site through the rest of the TAF period.

Note: AMD NOT SKED for AUO due to a weather observation outage.

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FIRE WEATHER

MinRH values will generally range between 35 and 45% the next few days, before slowly climbing into the weekend ahead of increasing rain chances. Winds will remain light the next few days, before increasing into the weekend as well. Fire weather concerns are currently low, but they will start to increase by Monday no meaningful rainfall occurs with this weekend's system.

PRELIMINARY POINT TEMPS/POPS

Gadsden 74 97 73 94 / 0 20 40 50 Anniston 73 94 72 92 / 0 10 30 50 Birmingham 76 95 74 92 / 0 20 30 50 Tuscaloosa 76 99 75 96 / 0 20 30 50 Calera 75 95 73 93 / 0 30 30 50 Auburn 74 93 74 91 / 0 20 30 50 Montgomery 75 98 74 96 / 0 20 30 50 Troy 73 96 73 95 / 0 30 20 60

BMX WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 9 PM CDT Thursday for the following counties: Autauga-Bibb-Chilton-Coosa-Dallas-Elmore-Fayette- Greene-Hale-Jefferson-Lamar-Lowndes-Marengo-Marion-Montgomery- Perry-Pickens-Shelby-Sumter-Tuscaloosa-Walker.

Heat Advisory from 9 PM this evening to 9 PM CDT Thursday for the following counties: Barbour-Bullock-Macon-Pike.