694
FXUS63 KDMX 250917
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
417 AM CDT Sat Jul 25 2026

.KEY MESSAGES...

- Dangerous heat builds in over the weekend with a heat advisory
  issued for Saturday. Extream Heat Warning issued through
  Sunday evening.

- 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 SUNDAY/...
Issued at 415 AM CDT Sat Jul 25 2026 We kick off Saturday
morning with areas of patchy fog with even some spots reaching
down to a 1/4 mile or less. After sunrise, temperaturs will
begin to warm and fog will burn off. Once that happens the
dangerous heat will begin to build. Temperatures will surge into
the 80s and 90s with possible upper 90s in northwest Iowa. You
will notice a significant increase in humidity this morning
compared to what we saw across the state on Friday. The
combination of hot temperatures, rising dew points and peak crop
evapotranspiration, heat indices will have no trouble reaching
the triple digits today for much of the area. A Heat Advisory is
now in effect for central and western Iowa, where confidence is
highest heat indices will near or exceed 105 degrees.

The hot temperatures and high dew points will prime the atmosphere
for storms. However, some limiting factors will keep most of central
Iowa dry this afternoon into the evening. The most significant
factor preventing storm formation will be a very strong Elevated
Mixed Layer (EML), which will create a strong cap to limit storm
initiation. That said, guidance remians consistent that a decaying
storm systerm will work into parts of northwest Iowa late tonight
into early Sunday morning. Dry air will be in place in the lower
levels, and if storms hold togeather as they enter northwest Iowa
late this evening, a damaging wind threat could occur. A Marginal
Risk (level 1 of 5) has been introduced across all of nothern Iowa
to highlight this threat.

High pressure will continue to dominate into Sunday leading to
another day with dangerous heat across Central Iowa. Lows Saturday
night into Sunday will be in the mid 70`s and we will carry over the
high dew points from the day before. Due to the lack of relief with
the warm overnight lows and daytime highs climbing back into the
90s, have upgraded the Extreme Heat Watch to an Extream Heat
Warning. Central Iowa is expected to see heat indices push near or
exceed 110 degrees.

While the main story for both Saturday and Sunday will certainly be
the heat, the headlines may shift from heat to severe weather by
late Sunday. Guidance is showing signals of a shortwave trough
impacting north central Iowa as well as southeast Minnesota to
southwest Wisconsin. Guidance suggests an MCS could form along the
thermal ridge where better forcing will be present. However, as
history has shown, models struggle with placement and track for
these overnight MCSs. This will be soemthing to keep a close eye on
in the coming days. One thing that we are confident in; there will
be plenty of instablity (2500 to 3500 J/kg of MLCAPE) and favorable
shear profiles (40 to 45 kts of 0-6km shear) to support severe
storms. One uncertainty that could limit storm development will be
the strong cap in place, as 850 temperatues look to range betwen 24
and 27C. Regardless, a slight risk (level 2 of 5) for severe weather
is in place over northern Iowa, with a marginal risk encompassing
the rest of the area late Sunday into early Monday.



&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
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 /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1102 PM CDT Fri Jul 24 2026

Ceilings have lowered over the central part of the state and
fog has developed over southern into portions of central Iowa
late this evening. Thus, confidence is high in IFR and LIFR
restrictions at the terminals through mid to late morning
Saturday. Conditions will then improve into VFR through the rest
of the period.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from noon today 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...TDR
LONG TERM...Vorst
AVIATION...Ansorge