921
FXUS63 KDMX 172337
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
537 PM CST Wed Dec 17 2025

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

.KEY MESSAGES...

- Mild temperatures and melting snow expected to continue for
  the rest of the afternoon to evening. Increasing winds this
  afternoon and evening.

- Precipitation chances return along a cold front late tonight
  into Thursday morning, falling as rain.

- Windy conditions, scattered snow showers, and falling
  temperatures then arrive mid-day Thursday behind a secondary
  cold front. Sudden travel impacts may develop under snow
  showers.

&&

.DISCUSSION...
Issued at 249 PM CST Wed Dec 17 2025

Quiet conditions remain over Iowa today as the region sits between
two systems: the first being an area of high pressure covering much
of the east/southeastern CONUS, and the second over the northwest
part of the country where surface low pressure is deepening. Low
level flow out of the southwest has led to another day of mild
temperatures with values currently in the upper 30s to low 40s where
the snowpack yet remains, and in the upper 40s to low 50s in the
southwest where bare ground is located. These temperatures will
allows for more snow melting to occur, likely continuing into the
evening with temperatures remaining above freezing. As the low level
southwest flow continues to increase through the rest of the day,
southerly winds will turn breezy into the evening and overnight,
with gusts up to 20 to 25 mph which is what will be keeping these
temperatures more mild. This will occur along with a gradual
increase in cloud cover ahead of precipitation chances returning
through this evening.

A dynamic system (the aforementioned low pressure currently
over the Pacific Northwest into Southern Canada) is still on
track to gradually track eastward into the Dakotas and through
the Upper Midwest tonight into Thursday, with a cold front
extending in Iowa this evening that will come with light rain
showers tracking eastward across the state. Guidance generally
has the rain entering western Iowa just before midnight, though
very light activity just ahead of the main wave may struggle to
reach the ground with the initial dry air. The overall forcing
for lift will be maximized after midnight until around sunrise
where the highest chances for rain will move across central
Iowa, before exiting eastward by mid- morning. Following a dry
slot filling into Iowa mid to late morning for a short period, a
secondary frontal passage from northwest to southeast is
expected, along with a more defined sharp decrease in
, passing through by late morning through the afternoon. Winds
are going to become very gusty during this time following right
behind the departing secondary front. Low level winds,
particularly at 850mb, depict values around 45-50 knots arriving
into Iowa shortly after sunrise through the afternoon, which
given the cold air advection with this and sinking air should be
easier to see these gusts mix down to the surface at times. The
expectation overall remains for surface winds to increase with
sustained values around 25-30+ mph and gusts up to 40-45+ mph,
especially across northwest Iowa by mid-morning through the
early evening. With increased confidence on this winds covering
much of central Iowa, have expanded the coverage of the Wind
Advisory further east in collaboration with neighboring offices
to include much of the eastern part of the CWA given trends in
latest guidance. These winds will slowly decrease into Thursday
evening and especially by Friday. Given the previously
discussed concern about flash freeze given the morning rain
followed by cold temperatures moving in, the window for drying
to occur, which will likely be enhanced by the windy conditions,
should dry many surfaces that should limit flash freeze
potential, though isolated areas such as those in shade may be
more at risk. Will continue to monitor this potential closely.
Additionally, in regards to the secondary frontal passage late
Thursday morning to afternoon, notable frontogenesis occurring
and forcing for lift moving northwest to southeast, along with
indicated CAPE values in around 40-60 J/kg suggests that the
potential for snow bursts or even a few snow squalls remains
possible. However there still remains uncertainty in the extent
of available moisture, as soundings indicate relatively dry low
levels, especially further south across Iowa. The better
potential does appear to be in northern Iowa where the moisture
availability is higher, but still will be battling some low
level dry air. Will have to continue monitoring the latest
guidance and conditions over the next several hours. In summary,
after the rain moves through tomorrow morning, snow showers
with some squall potential remains, with the higher potential
north, while advisory level winds are increasing in likelihood
over much of central Iowa. Impacts from the gusty winds alone,
along with the added potential for any light snowfall will lead
at least some travel impacts. Please stay tuned for additional
updates. As dry conditions return into Thursday evening,
temperatures will be quite chilly into early Friday with the
cold air overhead, with overnight lows expected in the single
digits to the north and in the teens to the south. Surface high
pressure quickly passes through Friday, with low level flow
switching back southwesterly that will bring some ``warmer`` air
back into the region, with highs expected in the upper 20s to
the northeast and in the upper 30s to the southwest.

The weekend looks mainly dry, though a system scraping the
Canadian/US border looks to bring a sagging frontal boundary into
Iowa, though the dry air overhead looks to keep any precipitation
chances quite minimal. Surface weak high pressure will move in late
Saturday to Sunday, followed by another large area of high pressure
passing southeast across the eastern portion of the Upper Midwest
into the eastern CONUS into next week. This will lead to dry and
generally quiet weather through Tuesday/Wednesday before the next
precipitation chance is suggested later Wednesday. Generally mild
temperatures are expected to continue this weekend into next week
with highs in the 30s to 40s and lows in the teens to 20s.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 534 PM CST Wed Dec 17 2025

Stratus lifting north from Kansas and Missouri will arrive
overnight and will bring MVFR to local IFR cigs. A period of
rain is expected at all sites overnight as well. A brief break
with a return to VFR is possible, mainly in the morning. A cold
front will move across Iowa late morning and into the afternoon.
Strong west to northwest winds will arrive with the boundary
passage along with more MVFR stratus. A few periods of snow may
occur, mainly over northern Iowa including KMCW.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 9 AM to 6 PM CST Thursday for IAZ004>006-
015-016-023>025-033>036-044>048-057>060-070>073-081>083-
092>094.
Wind Advisory from noon to 6 PM CST Thursday for IAZ007-017-
026>028-037>039-049-050-061-062-074-075-084-085-095-096.

&&

$$

DISCUSSION...Bury
AVIATION...Donavon