236
FXUS63 KDMX 230931
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
331 AM CST Sun Nov 23 2025

.KEY MESSAGES...

- Mild and dry weather continues into Sunday.

- Widespread dense fog possible tonight into Monday morning

- Rainy and dreary Monday into Monday night, then much cooler by the
latter half of next week.

&&

.UPDATE...
Issued at 331 AM CST Sun Nov 23 2025

Fairly quiet weather early this morning, with surface high pressure
into the western Central Plains that is influencing conditions over
Iowa, which are characterized by clear skies and light
west/northwest winds. The trough that tracked through the Upper
Midwest yesterday, now over Lake Superier will continue to depart
eastward today, with the aforementioned high pressure gradually
sliding southeast out of the region through the day. Upstream
satellite imagery indicates upper level clouds rounding the surface
ridge over the Dakotas, which are expected to arrive into Iowa a bit
later this morning, particurly across the far north. This however
should not affect morning lows in terms of reducing the efficient
radiational cooling that is ongoing early on this morning, with
current values in the 30s expected to drop further into the upper
20s north to low 30s further south closer to sunrise. Given some
lingering moisture over southern Iowa, along with the mostly clear
skies and light winds, some isolated patchy fog has formed, though
any further development per guidance looks to remain rather limited
to portions of southern Iowa before improving around or just after
sunrise. Temperatures warm through the day with plenty of sunshine,
resulting in another pleasant November day as values top out through
the 50s, so enjoy it if possible!

Will see conditions begin to change this evening, as stratus begins
to lift out of the Southern Plains as theta-e advection surges
northward. This will result in gradually increasing clouds from
south to north tonight into Monday, which is ahead of an ejecting
trough out of the Desert Southwest still slated to reach into Iowa
by Monday. Increasing warm air advection and moisture advection out
of the south looks to also come with the potential for advection fog
over the area as well tonight into Monday, as signaled by HREF
guidance with potential widespread locally dense fog across much of
Iowa. The HRRR is not as bullish but still indicates areas of patchy
to locally dense fog moving into south/southeastern Iowa late
tonight, then moving over northern and eastern Iowa by early Monday
morning where more widespread dense fog is signaled. While the
signal is certainly present given this information, more model to
model consistency will be evaluated today, which would in turn boost
confidence in this occurring if the signal remains, possibily
leading to a headline if warranted. Will certainly be keeping a very
close eye on trends through today.

Any fog looks to gradually dissipate mid to late morning Monday,
with the aforementioned trough lifting into Iowa and bringing
increasing precipitation chances (30-50%) by then, with the highest
chances (60-70%) into the afternoon as the deformation zone on the
northern fringe of this system passes overhead. Overall, initial
precipitation Monday morning looks very light and spotty per CAM
guidance, then increasing in coverage mainly over far south/east
Iowa by the afternoon to evening while the bulk of more notable
rainfall is expected south and east of Iowa given better forcing and
moisture availability over these areas. Given weak lift and low
level saturation over Iowa though, this precipitation looks to be
more drizzle to light rain, with a rather dreary day and overall
little accumulation expected around a few tenths or less.
Temperatures reach into 50s again despite the clouds, thanks to the
southerly flow.

By Tuesday, this system lifts northeast just ahead of a quickly
moving northern trough over the Dakotas, with guidance showing the
development of a more defined low pressure system into the Upper
Midwest, bringing another shot of moisture and forcing mainly
concentrated over MN/WI with it that looks to include at least
northern Iowa. Additional precipitation is possible Tuesday as a
result, mainly in the warm sector of this system over northern Iowa,
until strong cold air advection with northwesterly flow and a
tightening pressure gradient from the deepening surface low over the
Midwest brings much cooler conditions into the region late Tuesday
into Wednesday. Still seeing some potential for rain/snow over
northern Iowa at this time, but overall impacts look fairly limited
at this time but still of interest, so close monitoring will
remain.

&&

.DISCUSSION...
Issued at 247 PM CST Sat Nov 22 2025

Another pleasant day is on tap for Sunday, perhaps a few degrees
cooler behind today`s weak front, but otherwise looking pretty
similar. A low-amplitude ridge at 500mb ahead of the aforementioned
low in addition to low-level winds returning southerly should still
keep mild temperatures and sunny skies in play with highs reaching
the mid to upper 50s.

Sunday night into Monday, the upper low looks to eject out of the
Four Corners region and move northeast across the Central Plains.
Isentropic lift and moisture advection increase ahead of the system
Monday morning, helping to increase rain chances across Iowa.
Coverage should become more widespread from west to east
through the balance of the morning hours, per the latest CAM
guidance, with likely PoPs continuing through the afternoon.
PoPs decrease from west to east during the evening and
especially overnight with the upper trough axis pushing the main
area of ascent east after midnight. Rain amounts look light
overall, with most ensemble solutions producing a quarter inch
or less across the area. A few outliers give up to a half inch
of QPF, but that appears to be a 20% chance or less at any given
location. Additionally, there`s little to no instability to
work with to produce any thunderstorms, so that would help keep
amounts light as well.

Not far behind the Monday system, a Pacific shortwave trough is
progged to become more amplified as it traverses across the Northern
Plains and Upper Midwest. There remain some small differences in the
timing and strength of that system as it does so, which results in
some difference among solutions in how far south any associated
precip will develop. The latest forecast has increased PoPs slightly
across northern IA Tuesday, which seems reasonable. Depending on
timing of the system, there could be some snowflakes mixing in with
rain toward the evening as cold air advects in. This should have
little to no impact with only a few hundredths of QPF, but trends
will be something to watch at least. The main story with this system
will be the strong CAA bringing in a much cooler and drier air mass,
which sticks around through the end of next week. Highs are forecast
to drop into the 30s Wednesday onward with lows dipping into the
teens and 20s. Dry weather is forecast Wednesday through Friday with
northwest flow aloft.

To give an early look at the long range into next weekend, models do
show a trough in the western CONUS, which could produce a low
pressure system somewhere in the region. It`s far too early to get
any more detailed than that, as we really need to see more run-to-
run consistency closer to the time frame in question to get a handle
on how this may impact the local area.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1037 PM CST Sat Nov 22 2025

Kept fog mentions at KOTM only for tonight, but kept as BCFG as
better fog signal is in Missouri. VFR conditions expected for
much of the period, then fog and stratus begin to form after 00z
in southern Iowa. Added a SCT MVFR deck to KOTM and KDSM at 03z to
account for this (higher confidence in a BKN to OVC deck is
right at 06z). Fog will become more commonplace after the TAF
period ends and will likely be covered in the next TAF issuance.

&&

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

&&

$$

UPDATE...Bury
DISCUSSION...CP
AVIATION...Jimenez