779
FXUS63 KDMX 062343
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
643 PM CDT Sun Sep 6 2026

 ...Updated for the 00z Aviation Discussion...

.KEY MESSAGES...

- Flash Flood Watch issued for portions of northwest Iowa
  through Monday morning.

- Storms continue into Monday morning. Another round of severe
  storms possible Tuesday afternoon.

- Cooler temperatures and lower humidity arrive late week.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 322 PM CDT Sun Sep 6 2026

We kick off the first Sunday of September on an active note. Showers
and storms have lingered throughout the morning and into the early
afternoon, fueled by areas of deep moisture convergence. CAMS
suggested the potential for more organized cells to form due later
on increasing shear, but this has not yet materialized. Convection
continuing to develop ahead of the main line is disrupting
inflow to the primary updrafts and preventing the development of
a single dominant cold pool. Currently, storms are feeding off
a robust instability axis with MLCAPE around 3000 J/kg although
effective shear around 30 kts is keeping activity disorganized.
Regardless, a few severe storms still remain possible with
damaging winds being the primary concerns. Slow storm motions
and efficient rain have led to some areas recording 3-5 inches
of rainfall as storms train over the same areas. With storms
expected to persist through the afternoon, CAM QPF highlight
localized maximums potentially exceeding 5 inches over west
central Iowa. Consequently, the weather prediction center (WPC)
has outlined much of northwest Iowa in a Moderate Risk for flash
flooding, and a Flash Flood Watch is in effect. Somewhat
mitigating the flash flood threat are the dry antecedent
conditions; much of NW Iowa remains in a moderate drought, with
Ida County experiencing a small sliver of severe drought.

Tonight

Convection will continue to slowly shift south and east this
evening, gradually weakening with the loss of diurnal heating.
However, a Strengthening low level jet across central and
western Iowa could reignite scattered showers and storms late
tonight into early tomorrow morning. Severe weather is not
expected overnight as MUCAPE values drop to around ~500 J/KG.


Monday into Tuesday

Overnight showers and storms should diminish as we head into
tomorrow morning and drier air filters in for Monday. Winds across
northern Iowa will be breezy ahead of an approaching cold front, at
with gusts reaching up to 25 mph at times. Additional storms are
possible ahead of this boundary late Monday night into Tuesday
morning. A severe weather threat may materialize by Tuesday
afternoon; the Storm Prediction Center (SPC) day 3 highlights
central Iowa in a Marginal Risk. Details regarding this severe
threat will be fine tuned in future AFD issuances.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 322 PM CDT Sun Sep 6 2026

Storms will exit the region behind the cold front on Wednesday,
ushering in cooler temperatures and lower humidity. Highs in
the lower 80s are expected through Thursday, with precipitation
chances potentially returning by Friday.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 636 PM CDT Sun Sep 6 2026

A line of storms is moving east across Iowa this afternoon
leading to lower ceilings and visibilities, but impacts should
be minimized around 03z/10pm. KDSM and KFOD will see impacts
from rain but confidence in the eastern extent is lower, save
for KMCW where additional storms have developed. The storms over
KMCW will help clear the MVFR stratus in the area. After showers
and storms clear the area, prevailing VFR conditions are
expected at all sites. Winds tomorrow will be out of the east-
southeast and at northern terminals gusts around 20kts are
possible.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 4 AM CDT Monday for IAZ004-015-023-033-034-
044.

&&

$$

SHORT TERM...TDR
LONG TERM...TDR
AVIATION...67