510
FXUS63 KDMX 271946
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
246 PM CDT Mon Jul 27 2026

.KEY MESSAGES...

- Scattered non-severe thunderstorms are ongoing across southern and
southwestern Iowa and are expected to continue through sunset.

- Dangerous heat continues today before relatively cool
  temperatures set in tomorrow and Wednesday.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 246 PM CDT Mon Jul 27 2026

Somewhat scattered non-severe thunderstorms are ongoing across parts
of southern Iowa. This activity is expected to continue through
sunset. Mesoanalysis shows plenty of surface-based CAPE (upwards of
5,000 J/kg), healthy lapse rates from 6.5 to 7 degC/km, and bulk
shear values of around 30kts. Storms today could have some gusty
winds with them, and some more impressive storms have been tall
enough to potentially produce some small hail. Considering the lack
of any significant changes to the environment over the next few
hours, this trend is expected to continue. The limiting factor with
convection being more widespread is forcing, as the boundary these
storms are forming on is very weak. Behind this boundary, dewpoints
are expected to fall with the most drastic decreases being across
northwestern Iowa. Dewpoints will fall into the 60s and low 70s
instead of being in the upper 70s or even low 80s. In turn, this
will bring some (relative) relief from the extreme heat to northern
Iowa today before more widespread relief comes tomorrow.

As the aforementioned boundary makes it through Iowa, dewpoints will
be limited to the low 70s tomorrow and temperatures will be in the
mid to upper 80s. As a result, heat indices will top out around 90
which signals the end of heat headlines for now. Lows overnight will
still be pretty warm, however, in the upper 60s to mid 70s. With all
of this in mind, tomorrow looks to be dry with the lower dewpoints
leading to a lack of instability, strong capping in the low levels,
and little to no forcing mechanisms available. While daytime highs
continue to not be as extreme, overnight lows will still be fairly
warm, staying in the mid/upper 60s and low 70s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 246 PM CDT Mon Jul 27 2026

Warm and humid conditions continue through Friday before a pattern
change starts to take place. The 500mb ridge that Iowa sits on the
periphery on begins to shrink and move to the west. Temperatures
through most of the long-term will be cooler, with highs generally
in the 80s and overnight lows falling into the 60s across much of
the state. The long term looks to be fairly dry as well. There are
some lower thunderstorm chances Wednesday night into Thursday as a
shortwave is expected to ride overtop of the ridge. Most of the
activity should be out west in Nebraska. The placement of the
shortwave as it moves through will be better assessed tomorrow and
Wednesday. Thursday night, a low develops over the Dakotas and will
move to the east. This low will drive higher shower and thunderstorm
chances as it moves through, bringing with it a cold front, leading
to much lower temperatures than we`ve seen to start the weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1221 PM CDT Mon Jul 27 2026

VFR conditions are expected to prevail at all sites this
period. Winds across Iowa are in the process of shifting from
being south/southwesterly to northerly, and across northern Iowa
this shift has happened following a weak boundary that is
drifting across the state. Wildfire smoke will follow behind
this boundary, although FU mentions were removed from TAFs due
to low confidence in widespread visibility restrictions.
Otherwise through this evening, scattered showers and
thunderstorms are expected across southern Iowa. Low coverage
and confidence in location leads to no mention in the TAFs at
this time, but the most likely location to be impacted would be
KOTM.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 10 PM CDT this evening for IAZ004>007-
015>017-023>026-033-044.
Extreme Heat Warning until 10 PM CDT this evening for IAZ027-
028-034>039-045>050-057>062-070>075-081>086-092>097.

&&

$$

SHORT TERM...67
LONG TERM...67
AVIATION...67