304
FXUS63 KDMX 292338
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
638 PM CDT Wed Apr 29 2026

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

.KEY MESSAGES...

- Intermittent shower chances overnight tonight into Thursday.
  A few rumbles of thunder possible in southern Iowa Thursday
  afternoon. Severe weather threat is low.

- Cooler temperatures Friday and Saturday mornings may lead to
  frost development and a potential freeze. Make sure to cover
  any sensitive plants.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 250 PM CDT Wed Apr 29 2026

A well mixed boundary layer has also allowed for some breezier winds
today, primarily over the northern and eastern portions of the area
where the pressure gradient is slightly stronger. In addition to
winds, steeper lapse rates aloft have allowed for cumulus
development over much of central Iowa, leading to intermittent
sunshine today. Just upstream in Minnesota and South Dakota, weak
mid-level forcing and a slightly deeper unstable layer has allowed
for some scattered showers and even a few weak thunderstorms. This
wave is expected to translate south and eastward into Iowa this
evening, bringing the potential for a few scattered showers
overnight into early Thursday morning. Dry low-levels will inhibit
most precipitation from reaching the ground, especially south, but
model soundings and QPF output do suggest light rain will be
able to reach the surface early Thursday morning as the main
wave comes through. Instability will be negligible by this point
in the night/morning, so have kept this as primarily showers
overnight.

The mid-level wave will track southeastward through Iowa on Thursday
morning, with the potential for some reinvigoration as it moves
through southern Iowa and meets some better mid-level moisture
around mid-day. A shallow layer of instability will be present,
which may lead to a few rumbles of thunder, but even then MUCAPE
values are quite low (~150 J/kg) so no severe weather is expected.
Although the mid-level wave departs by Thursday evening, there is
some indication that scattered light showers/sprinkles could persist
Thursday night into Friday morning. These will be light and
transient, as they will also have plenty of dry air to overcome
before reaching the surface. Recent 12z guidance has also started to
put in even more light showers and potentially a few thunderstorms
Friday as yet another wave oscillates around the backside of the
Canadian upper low, so will refine these chances in the coming days
as well.

Aside from the perpetual light shower chances, overnight
temperatures continue to be the primary weather challenge this week.
Starting tonight and lasting through Saturday, we will see low
temperatures dipping into the 30s and even below freezing by Friday
and Saturday. This introduces some frost and freeze concerns for
more sensitive outdoor vegetation. Tonight into Thursday morning
will should remain warm enough to avoid these concerns, but Friday
and Saturday mornings may see temperatures falling into the low 30s.
Surface high pressure will attempt to fill in by Friday morning,
although with the recent trend towards more cloud cover & spotty
showers Thursday night may be able to mitigate radiational cooling
and cooler-than-expected lows on Friday morning. That said, with the
light winds and low dewpoints, any breaks in the clouds could cause
temperatures to plummet. Friday night into Saturday morning seems to
have less cloud cover concern, with high pressure parking directly
overhead and skies currently forecast to clear out after midnight.
This could cause temperatures to fall near 30 and even into the 20s
over far northern Iowa. It seems likely that we will see freezing
temperatures over at least a portion of the area one of these two
nights, but with the uncertainty created by the showers and cloud
cover tomorrow night, have decided to hold off on any headlines for
this shift.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Issued at 250 PM CDT Wed Apr 29 2026

Our pesky Canadian upper low will drift off to the northeast through
the weekend, allowing for upper ridging to begin pushing eastward
toward the state. This will put Iowa in a more broad northwest flow
pattern, which will be conducive for a somewhat active pattern into
next week. Warmer temperatures will also work their way into the
area early next week as the thermal ridging progresses eastward.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 634 PM CDT Wed Apr 29 2026

Clouds will become SCT to FEW overnight and light winds, mainly
from the southwest, will prevail overnight. An approaching wind
shift will bring a brief (1-2 hour) window of showers, mainly
for northern terminals and later in the afternoon for KOTM. KOTM
could also see thunderstorms, but confidence is low enough to
exclude mentions. Brief MVFR will be possible as the front is
overhead. Wind gusts to around 20kts will be common upon the
front`s passing.

&&

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

&&

$$

SHORT TERM...Dodson
LONG TERM...Dodson
AVIATION...Jimenez