818
FXUS64 KHUN 171822
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
122 PM CDT Mon Aug 17 2026

...New NEAR TERM...

.KEY MESSAGES...
Updated at 1026 AM CDT Mon Aug 17 2026

 - Dangerous heat will persist today, with Major (Level 3/4) to
   Extreme (Level 4/4) HeatRisk forecast along with heat indices
   between 100-110 degrees. A Heat Advisory remains in effect for
   all of northern Alabama and southern middle Tennessee through 7PM
   this evening.

 - A Slight Risk (Level 2/5) of severe storms is outlooked today
   for the far northeastern portion of NE AL and the far eastern
   portion of southern middle TN, with a Marginal Risk (Level 1/5)
   for much of the rest of the area. The main hazard with any
   severe storms will be damaging wind gusts.

&&

.NEAR TERM...
(Tonight)
Issued at 122 PM CDT Mon Aug 17 2026

Recently, the Storm Prediction Center extended both the Marginal
and Slight Risks farther west. So, There is a Slight Risk (Level
2/5) mainly east of I-65, with a Marginal elsewhere over our local
area. However, the overall forecast has not changed much.

Temperatures are currently hovering around the mid 90s, and with
a few more hours of peak heating, may increase a few degrees more.
This, along with dew points in the 70s, have resulted in heat
index values in the 103-107 degree range thus far for most
locations. Continue to practice heat safety and stay hydrated!

A small shower has developed to our north, but the overall
activity has not begun yet. We are still monitoring for convective
initiation (will likely be over our NE), but this may not really
ramp up for another hour or so. Regardless, the environment is set
up for downbursts with damaging winds gusts as the main threat.
Stay weather aware and take shelter if you hear thunder and/or a
warning is issued for your location!

Previous Discussion:

There are two points of concern for today - the dangerous heat
and strong to severe storm potential. For the heat, temperatures
are still forecast to reach the mid to upper 90s. This, combined
with dew points in the 70s, results in forecast heat indices in
the 105-110 degree range for most locations. Some spots may see
values a bit higher, but this is not expected to be widespread.
Therefore, there are no plans to upgrade any portion of the Heat
Advisory to an Extreme Heat Warning at this time. In addition,
afternoon/evening storm activity may dampen the heat just a bit
for the areas where they form (more on the storm potential below).
Ultimately, the Heat Advisory remains in effect for all of north
Alabama and southern middle Tennessee until 7PM this evening.
Please remember heat safety! Take frequent breaks in the shade,
drink plenty of water, and never leave people or pets in vehicles!

We also continue to monitor a cold front, which is currently
draped over Arkansas and pushing into Kentucky. This is still
slated to progress into the Tennessee Valley later this afternoon
and move south of our local area tonight. This feature, along with
remnant outflow boundaries, will be the forcing mechanisms for
storms to develop this afternoon. Instability will be abundant,
with models showing anywhere between 1500-3000 J/kg of CAPE across
the region. "Inverted V" model soundings indicate an environment
prime for downbursts. This can be seen in many downburst
parameters shown by model guidance as well such as WINDEX, 0-1km
lapse rates, and Theta E difference. Although, there are some
model discrepancies in some of these parameters, so there remains
a bit of uncertainty as to whether all of the parameters will be
met. Overall, confidence is low to medium in our severe threat
today; however, if storms do form, there are enough ingredients in
place for them to strengthen and become severe this afternoon and
evening. IN terms of timing for storms, the time frame remains
about the same, being roughly between 2-8PM then decreasing with
the loss of daytime heating later this evening. Overall, make sure
to have a safety plan in place for storms if you work outdoors or
have outdoor activities. When thunder roars, go indoors!

The shower and storm activity is expected to diminish by
midnight, with no showers or storms overnight. However, it will
still be humid and warm. Lows are forecast to merely drop into the
lower to mid 70s, with dew points in the lower 70s. Patchy fog
will therefore be a concern yet again overnight, especially for
areas that receive rainfall today, in sheltered valleys, and near
bodies of water. If you encounter fog while traveling
tonight/early tomorrow morning, make sure to leave room in between
you and the vehicle in front of you and use low beam headlights!

&&

.SHORT TERM...
(Tuesday through Wednesday)
Issued at 1026 AM CDT Mon Aug 17 2026

With FROPA tonight (Monday night) and high pressure building over
the Mississippi River and Ohio valleys on Tuesday, cooler and
drier air will be filtered into the region as a result. Therefore,
forecast highs in the upper 80s to lower 90s will be common on
Tuesday with dew points in the 60s. Although temperatures may
still seem a bit high, the even slightly lower temperatures along
with lower humidity will be a welcome change from the past few
days. Expect no rain, with only a few clouds during the day on
Tuesday as well. Lows Tuesday night will also be cooler, with
temperatures dropping into the mid to upper 60s.

We start to warm up again come Wednesday, with the aforementioned
high pressure shifting east over the Appalachians and another
cold front moving over the Midwest. While no showers or storms are
anticipated for the Tennessee Valley, highs are forecast to reach
the mid to upper 90s once again. Dew points begin to increase as
well, increasing into the upper 60s to lower 70s along and west of
I-65 on Wednesday. NWS HeatRisk highlights much of the local area
in a Moderate Risk (level 2 of 4), along with heat indices in the
98-103 degree range for most locations. More urban locations such
as Muscle Shoals in the west may see slightly higher heat index
values; however, this does not appear to widespread at the moment.
We will continue to monitor trends in case another Heat Advisory
may be needed, but confidence is low at this point. Regardless, be
safe if you have outdoor plans or work outside. Take frequent
breaks in the shade and stay hydrated!

&&

.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...
(18Z TAFS)
Issued at 1208 PM CDT Mon Aug 17 2026

VFR conditions will largely prevail today, except where
showers/storms occur this afternoon/evening. Lower CIGs and VIS
are anticipated where showers/storms do occur, along with the
potential for damaging winds and lightning in the stronger storms.
Expecting mainly a 19Z-01Z timeframe for any stronger to severe
storms. Activity will then diminish this evening, with no rain
overnight. The main concern overnight may be patchy fog,
especially in the river valleys and where rain falls today. Have
low confidence in fog at the TAF sites (especially at MSL), but
did include a slight reduction at HSV since the rain chances are
higher. This will be monitored through the day. Any fog will then
lift and dissipate through mid-morning on Tuesday. As for winds,
expect westerly winds around or just under 10 knots this
afternoon, with light and variable winds overnight.
North/northwest winds around 5 knots or so will then develop
through Tuesday morning.

&&

.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...26
SHORT TERM....26
LONG TERM....AMP
AVIATION...26