210
FXUS63 KDMX 110451
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1051 PM CST Wed Dec 10 2025

 ...Updated Forecast Discussion and 06z Aviation Discussion...

.KEY MESSAGES...

- Band of snow passes over northwest into central and southeastern
  Iowa Thursday into Thursday evening with accumulation of
  several inches possible. On the southwest side over portions
  of western and southern Iowa, light ice accumulations are
  possible.

- Accumulating snow Saturday with very cold air Saturday into
  Sunday. Cold weather headlines look increasingly likely early
  Sunday.

- Moderating temperatures and trending dry early next week.

&&

.UPDATE...
Issued at 1048 PM CST Wed Dec 10 2025

Still a fluid situation unfolding for Thursday. Precipitation
still on track to arrive Thursday afternoon from NW to SE. Mixed
precipitation and the freezing rain potential remains the
primary forecast challenge and it still appears there may be a
narrow corridor with minor ice accumulations. The transient
progression of the greatest forcing from southwest to northeast
as the warm advection and warm nose moves into southwest and
central Iowa may lead to some forecast adjustments upcoming.
That shift within a southeast moving band will also have an
impact on overall snowfall amounts as the area of better
dendritic growth will not be static. This has also led to an
overall shift northeast in the precipitation band. In addition,
this will also lead to an initial period of dendritic growth but
the forcing also will eventually lower into a less favorable
snow microphysics process leading to the generation of more
plates as opposed to dendrites. Plates are much less efficient
at snow to liquid ratios. Overall, this still translates to a
snow band with 1 to 3 inches possible and it may be more 1 to 2
inches with a few areas with 3. Freezing rain will be the main
winter headline driver. Solar radiation passing through the
clouds, latent heat release and the fact that any freezing rain
occurring in the "warmer" part of the system, may lead to road
temperatures AOA 32 degrees through mid afternoon. After 4 pm,
icing impacts may become more likely with the loss of that solar
radiation. Obviously we will continue to monitor and update as
needed.

&&

.DISCUSSION...
Issued at 227 PM CST Wed Dec 10 2025

Early afternoon satellite imagery from GOES-East Day Snow Fog
RGB shows widespread cloud cover over the state as the stout
shortwave trough (aka clipper) departs the region. There are
light snow showers passing over northeastern portions of our
forecast area into east central Iowa this afternoon. Iowa DOT
road cameras show little in the way of impact, but visibilities
down to around 1 mile have occurred at Mason City and similar
visibilities are possible downstream. While winds continue to
diminish this afternoon into tonight, there are still a few wind
gusts of 25 to 35 mph.

The fast, northwesterly flow continues to be the main driving force
behind our sensible weather into this weekend as a ridge persists
over the western US. The next clipper is just moving over the
British Columbia province this afternoon. This clipper will race
towards our region tonight with strong theta-e advection and
moderate QG convergence moving in after sunrise Thursday. As
this spreads into the state, the associated upstream surface low
pressure will near southwest Iowa and place much of Iowa under
the precipitation shield - the exception being parts of west
central into southwest Iowa. Cross sections show there is a
degree of low level frontogenesis, strongest in the GFS, with
saturation through the dendritic growth zone (DGZ) with moderate
lift at times over central into northern Iowa. Most models show
up to no higher than two to three tenths of an inch of liquid,
though the GFS is the higher outlier with a narrow ribbon of a
half an inch of liquid. Further, the QPF axis is shifting
southwestward compared to previous forecasts. This is based on
trends noted not only in past events, but also with models this
time around compared to the last night`s QPF axis. Many of the
global and ensemble members are southwest of the overnight
forecast`s QPF axis whereas many of the higher resolution models
are northeast of said axis. This forecast cycle trends the QPF
southwestward by a few counties and centers it more from
northwest Iowa across central Iowa into southeastern Iowa.
Precipitation type will be tricky as cross sections and BUFKIT
soundings show a warm layer trying to nose in around 850mb. This
introduces the potential for a wintry mix/freezing rain
potential on the southwestern edge of the precipitation shield,
which could range from a glaze up to near a tenth of an inch per
freezing rain accumulation model (FRAM). In the colder air
where it will snow, the profile will be warming and yield snow
ratios near climo of around 12:1. The QPF with these snow ratios
produces a band of 2 to around 3 inches centered on a line from
Estherville to Clarion to Iowa Falls that expands two or so
counties either side of the band`s axis. With the potential for
icing and the snow amounts, a Winter Weather Advisory was
considered. Uncertainty remains higher than normal for 24 hours
out from event onset given the shift in track along with the how
much freezing rain will occur so have held off with advisories
farther into Iowa in coordination with the Sioux Falls and the Quad
Cities offices.

Wintry precipitation will end overnight Thursday across the
area as the clipper departs and winds will remain on the lighter
side as they become from the north and northwest. Friday will
offer a break in wintry precipitation, but attention will turn
towards Canada as a more amplified shortwave trough moving into
the Great Lakes region combines with a more subtle shortwave
trough scooting beneath it. Mid-level thermodynamic and
kinematic forcing will be maximized over the state and yield a
period of accumulating snowfall over a good portion of Iowa on
Saturday. In addition, very cold air will funnel into the state
with highs Saturday and Sunday in the single digits above zero
over northern Iowa to the teens over far southern Iowa. As the
snow ends Saturday night and clouds clear into Sunday morning
with a large zone of high pressure moving in, overnight
temperatures will fall to around 20 below zero over northern
Iowa to the single digits below zero over southern Iowa. Wind
chill values of at least 15 below zero will be common by sunrise
Sunday with 30 below zero possible over northern Iowa. These
values would necessitate Cold Weather Advisories and Extreme
Cold Warnings (formerly Wind Chill Advisory and Warning,
respectively). As the high departs Sunday, flow will become
more from the southwest with ridging pushing over the central
US. This would offer rebounding temperatures and perhaps some
degree of confidence that temperatures may near normal for mid-
December with a period of dry conditions.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1048 PM CST Wed Dec 10 2025

A wedge of VFR conditions between two areas of MVFR stratus is
moving southeast into parts of central Iowa. This will bring a
period of VFR conditions at times overnight at most sites. A
system will arrive on Thursday and will bring increasing stratus
and precipitation. Most locations will have snow in the
afternoon while KDSM could have a period of FZRA mixed in at
times. The precipitation will end from northwest to southeast
from late afternoon through mid evening. Northwest wind will
become light overnight then transition to southeasterly on
Thursday.

&&

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

&&

$$

UPDATE...Donavon
DISCUSSION...Ansorge
AVIATION...Donavon