352
FXUS63 KDMX 221711
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1111 AM CST Sat Nov 22 2025

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

.KEY MESSAGES...

- Patchy fog remaining early this morning for much of the
  state, dissipating around sunrise.

- Mild, dry, and mostly sunny this weekend with highs around 53
  to 60 degrees Saturday and Sunday.

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

&&

.UPDATE...
Issued at 331 AM CST Sat Nov 22 2025

Chilly temperatures are being reported early on this morning, with
values in the upper 20s to mid 30s, coldest over portions of eastern
Iowa where mostly clear skies are present, while slightly warmer
northwest and south where more cloud cover is present that is
limiting the radiational cooling. Otherwise, another night of patchy
fog is ongoing over much of the state where skies are mostly clear
and winds are light, with visibilities generally between 3-6 miles
but have occasionally dropped below a mile at times over a few
localized areas such as at Waterloo and immediate areas nearby.
Expecting to see the clouds gradually depart through the morning,
which may introduce some patchy fog potential further south as well
given that winds will remain light until sunrise. Overall, expecting
any remaining fog to be generally patchy in nature, though some
brief localized dense fog is not out of the question but should be
limited enough to avoid any major impacts. Still, those who may come
across fog should drive slowly and leave extra space between other
vehicles as necessary. Towards sunrise, winds are expected to
gradually increase out of the southwest that will dissipate any
remaining fog. Given mostly clear skies expected overhead, with
stronger 850mb winds aloft, the trend in increasing winds a bit
higher remains logical, as good mixing is more likely to bring some
of the higher winds at the top of the boundary layer to the surface
at times by late morning to afternoon. The GFS seems to handle this
better with a drier sounding, with gusts around 25 knots at the top,
while the NAM is a bit more saturated with slightly lower winds.
Therefore, have increased winds a bit further for today to reflect
these expectations. Highs will be fairly warm for the time of year,
with highs through the 50s and possibly even low 60s in some spots.
A trough over the Dakotas passing through the Upper Midwest will
however bring a wind shift through the afternoon with a dry frontal
passage, switching winds to become west/northwesterly by the early
evening, then gradually decreasing with sunset. This wind shift will
be short lived, as winds turn southerly with a large area of high
pressure passing overhead Sunday, which will generally keep warm
temperatures into the region to end the weekend, as highs are again
expected in the 50s.

The dry period still looks to end by Monday, as a large trough
ejecting out of the southwest CONUS lifts up into the Central
Plains, and surface cyclogenesis occurs east of the Rockies. A
substantial push of mid and low level moisture with 850mb southwest
flow is expected to pass through Iowa as it lifts northeast and
bring widespread rainfall into the area. Generally speaking, the
trend is that chances gradually increase for rainfall over western
Iowa through the morning, becoming more widespread into the
afternoon. However, some differences remain between GFS versus Euro
in terms of the overall setup, as the GFS indicates moderate forcing
and lift into south/east Iowa with a more defined low pressure
system generating widespread precipitation over much of the state,
while the Euro keeps the better forcing further south and east, with
less rainfall overhead but still fairly widespread. The NAM seems to
favor a similar setup to the GFS, so will have to continue to
monitor this over the weekend. Regardless, there is minimal, if any
concern for storms as the setup for this potential generally remains
south and east of Iowa for this particular system of interest.

Regarding the forecast by mid-week, little change in guidance has
been noticed with the latest runs, as the overall trends remain in a
strong push of cold air advection later Tuesday and Wednesday as the
deepening system slowly departs the region, with windy conditions
possible and even some chance for snow mainly concentrated over
northern Iowa. Details beyond this are even more varied in
solutions. Please see the discussion below for more details.

&&

.DISCUSSION...
Issued at 202 PM CST Fri Nov 21 2025

Southwesterly breezes will continue into Saturday before the
next trough comes through during the afternoon. Even then, cold
air advection will be negligible and mostly clear skies and
prevailing southwest winds will send temperatures rising
notably higher during the day. Highs are still projected in the
mid to upper 50s and a few stations may reach 60 degrees.
Another surface high pressure area will build from Nebraska
into Iowa Saturday night, but will already be departing to our
southeast on Sunday afternoon allowing for another sunny, mild,
and pleasant day with highs very similar to Saturday. In other
words this weekend will be very favorable, given the season,
for many outdoor interests including those wishing to complete
yard work, holiday decorations, and other such endeavors before
winter comes. Any such interested parties are encouraged to
take advantage of the opportunity, as it may be the last period
so conducive for some time!

By Sunday evening a large 500 mb low will be emerging from the
Four Corners region over eastern Colorado, while concurrently an
energetic northern stream shortwave comes ashore over the
Pacific Northwest coast. As the southern system drifts
northeastward at the beginning of next week it will interact
with the more quickly eastward moving northern trough.
Initially, on Monday, the southern system will be reflected in
a broad surface low pressure trough advancing from the High
Plains into the Midwest and near or over Iowa. As this low
approaches, steady moisture transport and isentropic lift will
underlie the broad forcing for ascent along the leading flank
of the 500 mb trough, combining to produce thick clouds and rain
across most or all of Iowa Monday into Monday night. Rainfall
amounts will be modest and instability appears too limited for
any substantive thunder chances, so no hazardous weather is
anticipated. However, it will make for a gray, soggy late autumn
day before the system clears out late Monday night or early
Tuesday.

From Monday night onward the long-range models rapidly diverge
in their solutions for the remainder of next week, initially due
to difficulties in resolving the interaction between the
northern and southern stream systems early in the week. The GFS
is resolving this as a large closed 500 MB low over the eastern
Dakotas by Tuesday evening, while at the same time the EC and
GEM depict a more progressive open wave crossing
Minnesota/Iowa/Wisconsin. All solutions indicate some potential
for wraparound snow as this second push moves by, but the
variations between model runs affect the southward extent of
any such snow as well as its timing, with 12+ hour differences
between various solutions. However, there is a consistent
signal that if this Tuesday or Wednesday snow does pan out, it
will be more focused over Minnesota with some lower potential
in our northern counties. This system will move off to our east
by Thanksgiving morning, with northwesterly steering flow then
persisting through Friday. There are indications that a compact
but energetic shortwave may move through the flow late next
week, however there is a high degree of variability in model
solutions and any implications regarding snow potential are very
murky at this range. What can be said with confidence is that
it will be quite a bit cooler in the latter half of next week
behind the leading troughs, with current projections for
Wednesday to Friday showing daily highs in the 30s and overnight
lows around the mid-teens to lower 20s.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1111 AM CST Sat Nov 22 2025

VFR conditions will prevail through the TAF period. Southwest
winds this afternoon will turn to northwest later this evening,
then go light and variable by Sunday morning. There is a low
probability of fog, less than 20 percent, mainly at DSM and OTM
around sunrise Sunday. Have not included it in the TAFs at this
range, but will monitor for subsequent issuances in case
probabilities rise and warrant inclusion.

&&

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

&&

$$

UPDATE...Bury
DISCUSSION...Lee
AVIATION...Lee