884
FXUS63 KDMX 241934
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
234 PM CDT Fri Jul 24 2026

.KEY MESSAGES...

- Dangerous heat builds in over the weekend with a heat advisory
  issued for Saturday. Extreme Heat Watch issued Sunday through
  Monday.

- Additional showers and storms are possible later this weekend
  into early next week, with some potential for severe weather.
  Timing and location will be better determined in the coming
  days.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 233 PM CDT Fri Jul 24 2026

The latest regional surface analysis shows a surface trough tracking
over southern Iowa, which helped generate showers and thunderstorms
across the area earlier this morning. While the stronger synoptic
forcing remained south of the area, lingering shower activity
continues to work through southern portions of the region.
Widespread cloud cover and precipitation have kept temperatures
unseasonably cool, with highs only reaching the upper 70s across the
north and barely breaking 70 closer to the Missouri border.

Through the remainder of the afternoon and overnight, showers will
shift off to the southeast as surface high pressure begins to build
in. However, a warm front lifting through the region will advect low-
level moisture, leading to widespread low stratus and patchy,
locally dense fog overnight. Behind the front, an expanding upper-
level ridge centered near the Four Corners will exert its influence
over the region, ushering in dangerous heat for the weekend.
Temperatures will skyrocket into the upper 80s to mid 90s, with
isolated upper 90s possible across the west and northwest. The
combination of hot air temperatures, evapotranspiration, and
elevated surface dew points will produce heat indices ranging from
100 to 105 degrees, prompting a Heat Advisory for Saturday.
Additionally, because the DMX CWA sits on the periphery between the
upper ridge and strong northwest flow aloft, afternoon and evening
convection will remain possible. A strong EML will create a capping
inversion that could limit CI. However, if CI occurs, strong
instability and high effective bulk shear will support the risk for
isolated severe thunderstorms, primarily confined to the far
northeastern portions of the CWA.

High pressure remains dominant on Sunday, pushing high temperatures
into the low to upper 90s. Similar to Saturday, extreme humidity
will drive heat indices near 110 degrees. Temperature forecasts
carry slight uncertainty on both days due to potential lingering
cloud cover, convection, and smoke aloft carried by the
northwesterly flow. Nevertheless, with ensemble guidance showing a
90 to 100 percent probability of 850 mb temperatures exceeding 25
degrees C, these dangerous heat indices remain highly plausible.
Unlike Saturday, a shortwave trough embedded in the northwesterly
flow will provide better upper-level forcing to trigger showers and
storms Sunday afternoon and evening, increasing the probability of
strong to severe weather.

Morning rain and clouds are keeping temperatures cool today, but a
warm front and expanding upper-level ridge will bring rapid warming
and high humidity this weekend. Heat indices are expected to reach
100-105 degrees on Saturday (under a Heat Advisory) and approach 110
degrees on Sunday (under an Extreme Heat Watch). Despite capping
from an elevated mixed layer, disturbances moving through
northwesterly flow aloft could trigger isolated to scattered strong-
to-severe thunderstorms during the afternoon and evening hours both
days, with the highest storm chances arriving Sunday.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 233 PM CDT Fri Jul 24 2026

Hot and humid conditions are forecast to continue into early next
week. High temperatures on Monday will be very similar to those on
Sunday, but some relief is possible by Tuesday as the late-weekend
shortwave trough dives southeastward into the Great Lakes and Ohio
Valley. While the associated cold front is not particularly strong,
it will help temper the heat and humidity. Temperatures on Tuesday
will still reach the upper 80s to lower 90s, but surface dewpoints
are expected to drop by 10 to 15 degrees, yielding noticeably lower
relative humidity values. Unfortunately, the overarching synoptic
pattern will not break down, and warm temperatures will persist
through the remainder of the forecast period. However, some
temporary relief may occur via potential MCS activity along the ring
of fire in northwesterly flow around the upper ridge centered over
the Desert Southwest.

Dangerous heat and humidity will linger through Monday before a weak
cold front provides slight relief on Tuesday. While high
temperatures Tuesday will remain in the upper 80s and lower 90s,
noticeably lower dewpoints will lower relative humidity values. The
hot pattern will persist through the rest of the week, with
additional rain and temperature breaks tied to potential night-to-
morning MCS activity traveling along the ridge periphery.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1239 PM CDT Fri Jul 24 2026

Starting to see a lowering of CIGS as a surface low moves across
southern Iowa/northern Missouri. This will bring MVFR CIGS into
the afternoon before CIGS start to really lower into IFR to LIFR
with overnight with lowered VSBY due to patchy fog development.
Very little improvement in category is expected Saturday as low
CIGS remain overhead for the remainder of the TAF window.
However, western terminals will start to see a gradual
improvement after 16Z.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from noon Saturday to noon CDT Sunday for
IAZ004>006-015-016-023>025-033>036-044>048-057>060-070>073-081-
082-092-093.
Extreme Heat Watch from Sunday afternoon through Monday
evening for IAZ004>007-015>017-023>028-033>039-044>050-057>062-
070>075-081>086-092>097.

&&

$$

SHORT TERM...Vorst
LONG TERM...Vorst
AVIATION...Vorst