699
FXUS63 KDMX 080437
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1137 PM CDT Mon Sep 7 2026

 ...Updated for the 06z Aviation Discussion...

.KEY MESSAGES...

- Hot and humid across central and southern Iowa on Tuesday.

- Slow moving cold front will move across Iowa on Tuesday, from
  northwest in the morning to central Iowa by early evening and
  southwest Iowa overnight. Showers and thunderstorms with the
  front will produce pockets of heavy rain along with the
  potential for gusty winds.

- More seasonal with highs in the low 80s the rest of the week.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 230 PM CDT Mon Sep 7 2026

The area of morning showers and thunderstorms west of I-35 has
diminished into the early afternoon. As sun begins to peak out
temperatures are warming, though are much cooler than what was
seen through this weekend. So far highs today have been in the
upper 70s to low 80s. Temperatures will warm through the 80s
where there are breaks in the clouds this afternoon.

Meanwhile, if we zoom out a take a more regional look at current
conditions across the midwest, an elongated surface low is across
the western Dakotas This will move east across the upper midwest
over the next roughly 36 hours. The attendant cold front reaches
northwest Iowa early on Tuesday morning and will slowly sink across
Iowa through the day, not exiting southeast Iowa until Wednesday
morning. While northern Iowa will be cooled by rain through the day,
central and southern Iowa will be in the warm sector of the low.
Warm air advection will send temperatures back into the low 90s
across the the area with heat indicies around 100.

With strong moisture transport into the area, PWATs around 2", and
deep warm cloud layers over 4500 m, expect efficient rain production
and pockets of heavier rain. Storm motion is quick, but largely
parallel to the boundary as it very slowly sinks south. This may
result in training storms with higher rain amounts. While a
widespread 1-2" is possible, isolated pockets of 3-4". While
antecedent conditions are largely dry (except in western Iowa where
heavier rain fell Sunday evening), this could result in ponding or
flash flood issues in the heavier cores. The severe threat is fairly
low with these storms. While 0-6 km shear is around 50 kts, MLCAPE
is around 700 J/kg or less. Some reintensification of storms along
the boundary is possible in peak heating and gusty winds would be
the primary hazard. Storms continue into southeast Iowa overnight
before finally tapering off on Wednesday morning.

Cooler temperatures will filter in behind the cold front with highs
in the upper 70s north to low 80s south.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 230 PM CDT Mon Sep 7 2026

The cooler temperatures will last through the end of the week and
upcoming weekend. Keep in mind, while these temperatures may feel
cooler compared to last week, they will typical for this time of
year. The average high for this time of year is 77 in Mason City, 80
in Des Moines, and 81 in Ottumwa. After a couple dry days a
shortwave embedded in zonal flow will pass across Iowa on Friday and
bring the next round of convection to the area. A more robust system
Sunday into early next week with bring additional shower and
thunderstorm chances to the area. These successive systems will
help to knock a few more degrees off high temperatures. At this
time range there is uncertainty on the timing and track of
these systems, but guidance does agree that cooler temperatures
filter in by early to middle of next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1137 PM CDT Mon Sep 7 2026

Main aviation challenges continue to be on timing and impact of
storm chances at the terminals through the period. Storms over
Siouxland are moving in a general east-northeast fashion such
that have maintained PROB30 SHRA at MCW early Tuesday morning.
There should be an overall lull after any showers or storms
move through northern Iowa such that VFR conditions are forecast
until Tuesday afternoon. Then, storm development is expected
along the front and confidence is sufficiently high at this
time range to prevail TSRA at both DSM and ALO Tuesday evening.
For FOD and MCW, have prevailed SHRA with PROB30 TSRA given
lesser confidence in duration and coverage with any activity
arriving late in the period at OTM. Further restrictions and/or
refinement in timing will occur in future issuances.

&&

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

&&

$$

SHORT TERM...Hagenhoff
LONG TERM...Hagenhoff
AVIATION...Ansorge