795
FXUS63 KDMX 181140
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
540 AM CST Thu Dec 18 2025

 ...Updated for the 12z Aviation Discussion...

.KEY MESSAGES...

- Light rain with breezy winds out of the west northwest this
  morning.

- Strong winds, falling temperatures and scattered snow showers
  then develop through mid-day. Travel impacts possible. Strong
  crosswinds on north/south roads, as well as low visibility and
  slick conditions under snow showers.

- Mild and mostly dry through the weekend.

&&

.DISCUSSION...
Issued at 349 AM CST Thu Dec 18 2025

Light rain has begun over the western portions of the state early
this morning, as the first of our two cold fronts just now enters
the western fringe our forecast area. Precipitation that was being
progged ahead of the front in yesterdays guidance has really
struggled to make it`s way eastward through the dry mid-level air
this morning. In fact, most of the precipitation even along and
behind the boundary has been focused nearer to the gulf moisture
stream in southwest Iowa, with areas farther north struggling to
find enough moisture to saturate the layer, resulting in a lighter
rain in northwestern Iowa. As the morning progresses, the gulf
moisture will work it`s way farther north, allowing the boundary to
tap into the better moisture farther north in the area. However, it
seems much of north central Iowa may miss out on most of the rain
before the moisture stream phases with the front. Light rain is
still expected in these areas, but not nearly the coverage expected
24 hours ago. More persistent, light to moderate rain is still
expected in central and southern Iowa as the boundary works eastward
through the morning.

With the first cold front pushing into the area, breezy west
northwest winds are also picking up along and behind the boundary.
However, the main push of wind will come with the second, stronger
cold front which is currently producing wind gusts over 70 mph
upstream in the western Dakotas. Fortunately for us, the winds
aren`t expected to be nearly this extreme when they arrive in Iowa,
but will still be quite strong. West northwest winds of 25 to 35 mph
are likely, with gusts of 40 to 50 mph possible for much of the area
as the cold air moves in around mid-day. It`s possible a few areas,
especially in northwest Iowa, could approach High Wind Warning gusts
(58 mph or greater) with model soundings indicating 52 to 54 kt
winds for an hour or two late this afternoon/early evening. That
said, it`s difficult to tell if these are actually winds that the
mixed layer will be able to tap into, or if these are an artifact in
the model from the developing LLJ above the temperature inversion
aloft. Whether this is a real feature or artificial, expectation
would be for winds of this magnitude to be brief and isolated,
especially with the cold air advection and pressure gradient waning
as the stronger winds develop aloft. For these reasons, confidence
is too low for consistent enough winds to issue a High Wind Warning
and have stuck with the Wind Advisory for much of the area. The Wind
Advisory, however, has been updated slightly; it now encompasses all
of the forecast area, lasts until 9 PM (03z) for areas along and
west of Interstate 35 and until midnight (06z) for those east of
Interstate 35. It`s possible the advisory winds hold on for an hour
or two longer than 9 PM, especially over central Iowa, so will be
monitoring trends through the event for any needs to extend
additional counties in time.

In addition to the breezy winds, strong cold air advection and stout
frontogenesis along and behind the second cold front will bring
potential for convectively driven snow showers this afternoon and
evening. While moisture is generally lacking in the boundary layer,
a saturated layer will be present through the dendritic growth zone,
with both lift and a shallow layer of instability focused within the
layer. This will pose the risk for scattered, but efficient snow
showers this afternoon. Forecasted snow accumulations across the
area remain low, generally under an inch. However, some of the
convective allowing models (which will better capture
smaller/mesoscale features) are kicking out a quick inch or two of
snow in both Kuchera and Cobb snow ratio methods, especially
over northern Iowa. With the dry sub-cloud layer, it`s unlikely
accumulations of this magnitude are going to be widespread and
most will only see a dusting to no snow at all. But, the models
are alluding to the potential for heavier snow rates under these
showers, albeit localized. 1 to 2 inches isn`t a lot of snow,
but those amounts coming down in a brief amount of time in
conjunction with the strong winds could lead to sharp drops in
visibility under the showers. This is especially hazardous for
those traveling, as conditions could worsen quickly and
unexpectedly. Caution is advised if driving this afternoon.

Beyond today, forecast remains mostly dry and mild as we head
into next week, with all signs pointing towards near to above
normal temperatures heading into the Christmas holiday. Current
forecasted temperatures from the National Blend of Models (NBM)
puts highs in the upper 30s north, 50s south, and most of
central Iowa somewhere in the 40s through much of the week. It
is worth noting that these NBM highs, especially in northern and
north central Iowa, may be biasing a bit on the colder side due
to a) recent cold weather and b) the snow pack that has been in
place to varying degrees over the last few weeks. This is
likely causing NBM to bias high temperatures downward, given
recent trends during the colder, snowier weather patterns. The
snow pack will be all but gone by next week, so assuming the
current warmer pattern holds, would not be surprised to see high
temperatures for next week creep upward through the coming
days.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 532 AM CST Thu Dec 18 2025

A cold front passing through the area is bringing rain, MVFR to
IFR clouds, and gusty winds to the area this morning. Winds
directly along the leading edge of the front have been quite
strong, with gusts up to 45 kts being reported. These strong
winds are short- lived, but have tried to capture them at KDSM
and KOTM as the boundary moves through both locations. Winds
will remain breezy behind the front through the morning.

A secondary front moving through around mid-day will bring more
persistent strong winds as it passes through. Sustained winds of
roughly 20 to 25 kts are likely, with gusts up to 45 kts
possible at times this afternoon and evening. Scattered snow
showers may also accompany these winds, leading to sudden drops
in visibility and a dusting of snow. This will be most likely at
northern sites, so have included PROB30 groups for snow showers
at these locations. However, although confidence is low at this
time, certainly possible these showers get as far south as KDSM
and KOTM as well. Winds stay strong through the evening, then
diminish into the morning hours.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 9 AM this morning to 9 PM CST this evening
for IAZ004>006-015-016-023>025-033>036-044>048-057>060-070>073-
081>083-092>094.
Wind Advisory from noon today to midnight CST tonight for
IAZ007-017-026>028-037>039-049-050-061-062-074-075-084>086-
095>097.

&&

$$

DISCUSSION...Dodson
AVIATION...Dodson