769
FXUS64 KHUN 170554
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1254 AM CDT Mon Aug 17 2026

...New AVIATION...

.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...
(06Z TAFS)
Issued at 1254 AM CDT Mon Aug 17 2026

For the most part, VFR flight conditions should continue for the
greater TN Valley. But a few reports of patchy fog have been noted
around the region thanks to moisture loaded environment. We cannot
rule out an instance of fog impacting a terminal before daybreak,
with chances of it too low to mention in the TAF. More notable is
a cold front moving to the region this afternoon and evening. With
strong daytime heating and high instability, convection should
form this afternoon. Some of the storms could produce strong to
severe outflow wind gusts, as well as heavy downpours from lowered
CIG/VSBY. Shower activity should fade after sunset with VFR
conditions expected thereafter.

&&

.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....AMP.24
LONG TERM....AMP.24
AVIATION...RSB