textproduct: Huntsville

KEY MESSAGES

Updated at 956 PM CDT Sun Aug 16 2026

- Dangerous heat will impact the Tennessee Valley through the middle of this week, with Major (Level 3/4) to Extreme (Level 4/4) heat impacts forecast.

- A Heat Advisory is in effect for all of northern Alabama and southern middle Tennessee through 7 PM Monday, with extensions on the table in future updates through potentially mid-week. - A Slight (2 out of 5) risk for severe thunderstorms is forecast Monday across eastern Franklin County Tennessee and portions of far northeast Alabama, with a Marginal (1 out of 5) risk through most of the area.

NEAR TERM

(Rest of tonight and Monday) Issued at 956 PM CDT Sun Aug 16 2026

Tranquil weather across the Tennessee Valley this evening, with high pressure promoting clear/calm conditions. Despite this, expect another very warm night with lows only dropping into the mid 70s in most locations. The heat will again be a concern on Monday, with good heating in the morning allowing highs to climb into the mid to perhaps upper 90s by the early afternoon. Combined with dewpoints in the 70s, this will create heat index values between 105-110 degrees in most locations. A Heat Advisory remains in effect for the entire region until 7 PM Monday.

In addition to the heat threat, a weak front will drop south into the region on Monday, serving as a focus for low to medium (30-50%) chances for afternoon and evening thunderstorms. The thermodynamic environment will be favorable for some of these storms to become severe, with MLCAPE values around 2500 J/kg, low- level lapse rates around 8.5 to 9 C/km, and DCAPE values as high as 1200-1400 J/kg. Localized damaging winds in the form of downbursts will be the primary threat, along with locally heavy heavy rainfall (PWATs around 2").

SHORT TERM

(Monday night through Wednesday) Issued at 956 PM CDT Sun Aug 16 2026

Convection will wane in the evening hours as the boundary drops south of the region. Some patchy fog may develop in locations that receive rainfall late Monday, but otherwise it should be a fairly tranquil night. An ever so subtle change to the air mass may take place Tuesday as dewpoints will run a little lower and subsequently heat index values in the 100-105 degree range will be more common. Still, Moderate (Level 2/3) to Major (Level 3/4) heat impacts are forecast and everyone should still observe common sense heat safety. Heat impacts will temporarily creep back into the region on Wednesday as highs return to the mid to upper 90s and dewpoints in the 70s push peak heat index values above 105 degrees over much of the area.

LONG TERM

(Wednesday night through Sunday) Issued at 956 PM CDT Sun Aug 16 2026

After Wednesday, the upper-ridge will begin to flatten and shift back to the west over the southern Rockies and Great Basin. This will place the Tennessee Valley into northwest flow aloft, opening us up to a couple of shortwaves that will push through the area Thursday and Friday, resulting in medium (30-60%) chances for showers and thunderstorms both afternoons. A front will sag south of the area by the weekend, keeping the better chances for showers and storms displaced to south of us across central and south Alabama. This will also give us a relative break from the heat as highs will drop to the upper 80s to lower 90s, with overnight lows in the 60s by the weekend.

AVIATION

(00Z TAFS) Issued at 616 PM CDT Sun Aug 16 2026

VFR conditions will prevail at each terminal through much of the period. However, SHRA/TSRA will develop along a front Monday afternoon which could result in localized MVFR conditions due to reduced visibilities/ceilings. Have handled this with a PROB30 for now between 19-00z. AWWs and amendments may be needed during this timeframe.

HUN WATCHES/WARNINGS/ADVISORIES

AL...Heat Advisory until 7 PM CDT Monday for ALZ001>010-016.

TN...Heat Advisory until 7 PM CDT Monday for TNZ076-096-097.