287
FXUS63 KDMX 170955
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
355 AM CST Wed Dec 17 2025

.KEY MESSAGES...

- Mild temperatures and melting snow expected again today.
  Increasing winds this afternoon and evening.

- Precipitation chances return along a cold front overnight
  tonight into early Thursday, falling as mostly rain with a
  brief rain/snow mix possible north.

- 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 350 AM CST Wed Dec 17 2025

Winds remain light out of the west northwest, but just strong enough
to keep fog from developing so far this morning. There does remain a
chance for some patchy fog development as winds diminish under the
approaching high pressure this morning, primarily over the snowpack
where dewpoints are in upper 20s to low 30s. That said, we will
still need a few more degrees of cooling with temperatures remaining
a bit warmer than expected behind the front. Even still this
morning, temperatures are in the low to mid 30s and generally near
to above freezing. This all to say, fog is far from a high
confidence scenario, but will be monitoring for any development as
temperatures continue to fall this morning. As temperatures dip
below freezing, also be on the lookout for slick spots to develop
from re-freezing of melted snow.

Surface high pressure remains overhead through this morning, then
winds steadily flip to more southerly on the backside of the high
and ahead of the approaching 500 mb wave. This will once again boost
temperatures into the upper 30s to 40s today, with the coldest air
of course being over the remaining snowpack. The steady stream of
warmer, higher dewpoint air from the south will advect over the
snowpack and work diligently at melting it away again today.
Pressure gradients tightening ahead of the approaching wave will
lead to breezy conditions later today and into tonight,
reinforcing the warm, moist southerly flow even through the
overnight hours.

The aforementioned 500 mb wave is currently making landfall over the
pacific northwest early this morning, and will eventually close off
and dive southward through the Dakotas tonight, arriving in Iowa
early Thursday. Following the push of warm air ahead of this wave
will come two separate cold fronts in quick succession; the first
arriving overnight tonight into early Thursday, and the second
arriving around late morning to midday Thursday. The first front
will have a fairly healthy supply of gulf and pacific moisture, as
well as respectable lift along the front, brining the return of
precipitation chances primarily overnight tonight and prior to day-
break. This precipitation still looks to fall as mostly rain for
much of the area, although some model soundings do indicate a
potential, brief rain/snow mix on the back edge of the
precipitation, primarily in northern Iowa. The second front will
then bring a stronger push of cold air, and with that strong cold
air advection will come increasing winds and steepening lapse rates.
Winds of 25 to 35 mph are expected behind this front, with gusts up
to 40 to 50 mph possible. The strongest of these winds and gusts
will be in the western portions of the state. For this reason, a
Wind Advisory has been issued for Thursday in areas generally along
and west of I-35. It`s possible this advisory will need to be
expanded farther west, should confidence in strong winds increase
farther east in the area.

The final aspect of this system will also be the potential for some
convectively driven snow showers behind the secondary front.
Moisture will be lacking on the dry side of the system, but model
soundings do indicate these steeper lapse rates and strong
frontogenesis occurring within the dendritic growth zone, suggesting
the potential for a quick, efficient burst of snow along and just
behind the front. This shot of snow, in addition to the gusty winds,
could result in sharp drops in visibility. Combine this with a
dusting of snow over potentially refrozen rain water/snowmelt, and
impacts to travel may occur. Any snow accumulations will be minimal,
so impacts wouldn`t be long-lived. However, a sudden and potentially
unexpected worsening of travel conditions can be just as dangerous
for those impacted by it.

Temperatures cool off considerably Thursday night into Friday, but
begin to rebound during the day on Friday as southerly flow returns
after mid-day.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1033 PM CST Tue Dec 16 2025

Trend this cycle has been to focus fog at FOD with IFR
restrictions and remove the fog at the other terminals where VFR
conditions are forecast to now prevail. It`s possible the FOD
restrictions may need to be dropped into LIFR, but with most of
it occurring after 12z will allow a final look at that issuance
time. Otherwise, focus will be on Wednesday evening as winds
increase ahead of a front. Precipitation will arrive close to or
more likely after 6z so did not mention any this cycle.
Finally, a period of low level wind shear may develop toward and
after sunset, but with it being around 30 knots/marginal over
the north and less than 30 knots over the south have opted to
not include at in the last quarter of the period.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 9 AM to 6 PM CST Thursday for IAZ004-005-
015-023>025-033>036-044>048-057>060-070>073-081>083-092>094.

&&

$$

DISCUSSION...Dodson
AVIATION...Ansorge