121
FXUS63 KDMX 231737
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1237 PM CDT Thu Jul 23 2026

 ...Updated for the 18z Aviation Discussion...

.KEY MESSAGES...

- Cooler temperatures will be in place through the work week
  before another warmup this weekend.

- Showers and a few storms this evening through Friday morning
  across central and southern Iowa. Pockets of heavy rain are
  possible, especially in southwest Iowa.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 232 AM CDT Thu Jul 23 2026

High pressure remains firmly in place across the area early this
morning, while to the west an embedded shortwave is riding the
thermal ridge and will make another run at western Iowa later today.
Upper level moisture has begun to stream in aloft with increasing
cloud cover overnight. The incoming low will still have to battle
substantial dry air and it will take most of the day for profiles to
sufficiently saturate. With the thermal ridge still off to the
west and precipitation not yet into the area, today will be
another rare cool July day.

By late afternoon into the evening better moisture arrives, thanks
in part to the increasing low level jet. Warm cloud depths remain
4000+ m along with PWATs exceeding 2". An important change is a
shift in the track of the shortwave, which does not make it as far
east as earlier guidance suggested. This shifts the expected axis of
precipitation slightly to the west with the heaviest rain now expect
to fall west and south of the area. Even so, conditions favor
efficient rain productions once the column sufficiently
saturates overnight and pockets of heavy rain are possible,
especially in southwest Iowa. While dry antecedent conditions
and mature crops will help to mitigate most hydro concerns
problems may still be possible, especially in town. The
shortwave is expected to skim south of the area on friday with
rain tapering off across Iowa through the morning. This will be
the final cool day for the midwest with the western US thermal
ridge beginning to shift east.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 210 PM CDT Wed Jul 22 2026

Ensembles continue to suggest the central Plains ridge strengthens
and advances eastward on Saturday. This will bring in heat by
Saturday afternoon, and even warmer temperatures Sunday.
Temperatures near 90 appear likely Saturday, and perhaps mid 90s by
Sunday. Tropical storm Bertha will be nothing more than a breeze by
the weekend and should allow for an open gulf moisture stream.
Evapotranspiration is also near its peak at this point in the
summer. At this time, it looks like dewpoints will rise to at least
the mid 70s. This would adjust apparent temps up by several degrees
and give us potential for 100+ heat indices Saturday through Monday
in some locations. The position of the ridge and fairly strong mid-
level flow Sunday into early-week will put our area in ring of fire
position with potential for several rounds of strong storms.
High instability and potential for a decent nocturnal LLJ makes
Sunday into Monday the current best estimate for the next
chances at severe weather, but details are unclear at this time.
The jet pattern becomes less clear after Monday, and confidence
in storm chances is low beyond Monday.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1237 PM CDT Thu Jul 23 2026

Areas of diurnal cumulus are expected to increase in coverage
through this afternoon before fading after 00-01z, with ceilings
near MVFR at times. Otherwise, will see a gradual increase in
mid to upper level clouds this evening and especially through
Friday morning as a system approaches the region. Rain showers
are expected to increase across the state mainly after 06z, with
impacts mainly expected to occur at KFOD, KDSM and KOTM.
Adjustments on exact timing are expected to continue over the
next few issuances in accordance with latest model trends. Winds
will generally remain light out of the southeast today, then
increase with slightly breezy winds near the end of the current
period.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SHORT TERM...Hagenhoff
LONG TERM...De Bruin
AVIATION...Bury