textproduct: NWS Birmingham

KEY MESSAGES

Issued at 1251 PM CDT FRI AUG 21 2026

- Heat: Major HeatRisk will continue today, with heat indices forecast between 105 to 109 degrees. Heat Advisory remains in effect.

- Thunderstorms: Severe storms are expected this afternoon across southern Central Alabama, with damaging winds and heavy rain remaining the main concerns.

DISCUSSION

(This afternoon through Thursday) Issued at 1251 PM CDT FRI AUG 21 2026

The KBMX radar reveals a few lingering showers from this morning's convective activity. A quick look at water vapor imagery reveals an upper trough situated across the Tennessee Valley and an upper ridge building out to our west. At the surface, a cold front can be analyzed drifting slowly across the northern half of the state. This boundary will continue its southward movement through the day. Meanwhile, a shortwave will round the base of the trough, triggering another round of convection, generally to the south of the front. SPC maintains a Marginal Risk (Level 1 out of 5) for the southern half of the CWA due to the threat of damaging wind gusts. Forecast soundings once again suggest ample instability, dry mid-level air, and high DCAPE which supports the threat of downbursts with today's storms. Additionally, PWATs nearing 2" (per the 12Z KBMX sounding and GOES TPW imagery) would lead to heavy rainfall and a localized flash flooding threat.

Narrowing dew points, condensation pressure deficits falling to 2- 5mb and light winds in the wake of today's convection will help promote patchy fog development around sunrise Saturday morning. Fog will be most likely for those that receive rain this afternoon and evening.

Upper-level ridging will attempt to build in over the weekend. Increased subsidence and drier air will lower rain chances through the weekend, though precipitation looks to return early next week as a series of shortwaves rotates through with the northwest flow aloft.

High temperatures will continue in the low to mid-90s over the coming days. Persistent humidity will promote daily heat indices in the 105-109 degree range today. The Heat Advisory remains in effect through 02Z Saturday. Drier air arriving this weekend will help keep heat indices in check, generally in the 95-100 range.

95/Castillo

AVIATION

(18Z TAFS) Issued at 1251 PM CDT FRI AUG 21 2026

VFR conditions are currently in place across all terminals. Similar to the last few days, scattered showers and storms are likely this afternoon and evening. Convection will be more isolated for BHM/EET/TCL and scattered for AUO/MGM. MVFR cigs/vis and gusty winds will be likely with any passing storms. Will continue with PROB30 mentions to account for this activity. As winds become light overnight, there will be a low (20-30%) chance for patchy MVFR fog around sunrise. Best chances will be at terminals that receive rain this afternoon and evening.

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

95/Castillo

FIRE WEATHER

Relative humidity will generally remain elevated today, with lingering moisture across the area. Low to moderate rain chances will persist through today before a drying trend takes hold this weekend. Drier air filtering into the area on Saturday will result in a decrease in relative humidity (35 to 45%) for most locations. However, wind speeds are expected to remain light, which should negate any significant fire weather concerns during this period. Moisture gradually begins to return early next week.

PRELIMINARY POINT TEMPS/POPS

Gadsden 70 94 70 92 / 10 0 10 10 Anniston 70 92 69 91 / 10 0 10 10 Birmingham 72 93 72 92 / 10 0 10 10 Tuscaloosa 73 98 73 96 / 10 0 10 10 Calera 72 94 72 93 / 20 0 10 10 Auburn 72 91 72 90 / 40 0 0 0 Montgomery 73 96 73 96 / 30 0 0 0 Troy 72 95 71 95 / 40 10 0 0

BMX WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 9 PM CDT this evening for the following counties: Autauga-Barbour-Bibb-Bullock-Chilton-Dallas-Elmore- Fayette-Greene-Hale-Jefferson-Lamar-Lowndes-Macon-Marengo-Marion- Montgomery-Perry-Pickens-Pike-Russell-Shelby-St. Clair-Sumter- Tuscaloosa-Walker.