797
FXUS63 KDMX 261949
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
249 PM CDT Sun Jul 26 2026

.KEY MESSAGES...

- Dangerously hot conditions persist through Monday.

- Severe weather potential remains this evening into Monday morning,
but there remains uncertainty in location and timing  of storms.

- Slightly less warm and humid conditions are expected Tuesday
through mid to late work week, with largely dry weather  expected
until Thursday/Friday.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 247 PM CDT Sun Jul 26 2026

Very warm and humid conditions are continuing to expand across the
state as upper-level ridging nudges eastward and low level theta-e
advection remains strong into Iowa. Warmest conditions are reported
over the southwest half of Iowa with values in the mid to upper 90s,
paired with dewpoints in the upper 70s to low 80s and resultant heat
indices in the 110-115+ degree range. Those currently outdoors or
those wanting to spend outdoors need to practice heat safety to
avoid potential heat illness, which in these conditions only takes a
short amount of time to develop. Mid to upper level clouds are noted
over much of northern and eastern Iowa early this afternoon, which
have kept temperatures less oppressive but still warm in the upper
80s to low 90s, while dewpoints read in the low to mid 70s.
Expecting temperatures to increase further this afternoon given
breaks in the cloud cover that will expand east/south with time for
the rest of the day, with highs in the mid to upper 90s for most
locations in Central Iowa and dewpoints topping out in the mid 70s
to low 80s, resulting in widespread 110-115 degree heat indices. The
Extreme Heat Warning therefore remains in effect across the entire
area. A look at radar does shows returns over eastern South Dakota,
southern Minnesota and northern Iowa as rain and weak storms
continue to linger southeastward from a passing shortwave trough.
This activity could continue southeast through the rest of the
afternoon, though remaining elevated over the strong 24-26 degree C
850mb layer of air. Something to monitor through the afternoon but
the overall severe risk appears low at this time.

Near sunset this evening and into the overnight may come with
continued potential for shower and storm activity into the
Midwest, as the low level jet gradually strengthens from Kansas
through Iowa and into Wisconsin as the aforementioned shortwave
tracks further eastward. Model guidance has continued to be
more consistent on a developing MCS somewhere over northern
Minnesota into Wisconsin, strengthening with time into the night
as it dives south through Illinois and even parts of far
eastern Iowa. This is reasonable considering the placement of
better upper level support of forcing for lift. Further west
though, there is still some indication for a lesser defined area
of thunderstorms developing somewhere over eastern South
Dakota/Nebraska to western Iowa, also diving south/east into
Monday morning. Most CAM guidance has this activity over
northwest Iowa late this evening, tracking south/southeast on a
weakening trend. Uncertainty still remains rather high on
whether storms will impact the forecast area. The environment
overhead will certainly be favorable to support the potential
for severe weather though, with MLCAPE values around 1000-2000
J/kg and relatively steep lapse rates, along with shear values
around 30 knots. This activity however will be elevated given
the presence of the strong cap aloft as mentioned above, keeping
any potential for surface- based convection further east over
the Great Lakes. That said, large hail and especially damaging
winds will be the primary threats of concern if storms do move
through the area. This will be monitored very closely with
future runs in model guidance and monitoring of trends as
development occurs through this evening, so please stay tuned
for updates.

Any storms in the area would diminish near sunrise if not earlier,
though clouds could remain slow to decrease and therefore slow
warming. A dry boundary passage looks to follow around mid-morning
as it enters northern Iowa, slowly tracking southeast through the
afternoon. While surface winds shift north/northwesterly during this
time, temperatures are not expected to fall behind the boundary
given the expected increased mixing down of the warmer 850mb temps
aloft. However, this boundary has a sharp moisture gradient, with
much drier air behind it that should in turn keep heat indices
slightly lower over northern to north central Iowa, while areas
further south keep dewpoint values through the 70s throughout much
of the day. Another aspect of note will be the return of wildfire
smoke behind this boundary, with guidance suggesting smoke reaching
the surface, especially into northern Iowa. This smoke overall could
limit temperatures from reaching as high as forecast, but only by a
few degrees at most. With all these variables in mind, confidence
remains higher that temperatures will still soar through the 90s
over the forecast area, with the highest heat index values over
southern Iowa through portions of north-central Iowa in the 105-110
degree range, where the Extreme Heat Watch has been converted into
an Extreme Heat Warning through Monday evening. Where dewpoints will
be lower in the north/northwest, a Heat Advisory now replaces the
previously issued Extreme Heat Watch in those areas. Regarding the
boundary, this could be a focus area for the development of some
shower and storm activity, but with the strong cap overhead and lack
of a notable lifting mechanism, dry conditions should hold for the
remainder of the day.

Into Monday evening and night, another mid-level shortwave riding
the larger scale flow of the thermal ridge is suggested to descend
across the Dakotas and into Iowa into Tuesday morning. Better
forcing aloft is indicated mainly west of the forecast area over
Nebraska, and a lack of LLJ support is also noted. Limited shear and
instability overhead per soundings as well will keep thunderstorm
chances minimal, and even rain chances into western Iowa considering
the pronounced low-level dry air. Therefore have kept most areas dry.


&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 247 PM CDT Sun Jul 26 2026

Conditions generally are expected to remain dry Tuesday, outside of
the low potential for showers and weak storms to the west early on.
Surface high pressure is forecast to track southeast into the Upper
Midwest, with its influence generally over Iowa through Wednesday.
Temperatures will be a touch cooler through midweek, with values in
the upper 80s to low 90s, and dewpoints in the 60s, ending the
stretch of the dangerous heat. While another weak wave could bring
another low potential for rain in the western Central Plains
Wednesday morning, a more potent wave is signaled to descend on the
eastern fringe of the upper western ridge in the late work week,
bringing some potential for more widespread shower and storm
activity then. Specific details will be better known in the coming
days as more data becomes available from additional model members.
Temperatures look to trend cooler into next weekend, with average
highs in the low to mid 80s and dewpoints in the 60s, which will be
a welcome break from the previous heat.


&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1234 PM CDT Sun Jul 26 2026

VFR conditions are expected to continue for the rest of today,
with scattered to broken cloud cover tracking southeast across
Iowa. Overnight, increasing LLWS is expected as the low level
jet strengthens, which is expected across the forecast area
until just after sunrise. Otherwise, there does remain a low
potential (<30%) for storms in the area this evening into Monday
morning, though details on timing and coverage remain quite
uncertain given differing model solutions. Close monitoring
will continue into this evening, with possible additions to any
particular site where confidence in occurrence may increase.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Warning until 9 PM CDT this evening for
IAZ004>007-015>017-023>026-033-044.
Heat Advisory from 9 PM this evening to 10 PM CDT Monday for
IAZ004>007-015>017-023>026-033-044.
Extreme Heat Warning until 10 PM CDT Monday for IAZ027-028-
034>039-045>050-057>062-070>075-081>086-092>097.

&&

$$

SHORT TERM...Bury
LONG TERM...Bury
AVIATION...Bury