823
FXUS63 KDMX 301746
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1146 AM CST Sun Nov 30 2025

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

.KEY MESSAGES...

- Strong winds will cause blowing snow impacts this morning,
  especially from the Des Moines metro area northward and
  eastward where a Winter Weather Advisory is now in effect
  until noon.

- More snow is likely on Monday, especially across the
  southern/southeastern half of Iowa. Light to moderate
  accumulations are possible with the highest amounts near the
  Missouri border.

- Much of this week will be substantially colder than what has
  previously been experienced this season, especially today and
  even more so around Thursday. Lows Thursday morning will fall
  well below zero across the area, albeit with light winds.

&&

.DISCUSSION...
Issued at 314 AM CST Sun Nov 30 2025

Snowfall has ended across the area overnight, necessitating the
end of the Winter Storm Warning. However, strong northwest winds
continue with a tight surface pressure gradient in place and
gusts to near 35 MPH being reported. This is blowing the fresh
deep snow pack, resulting in moderate visibility reductions to
around 2-4 miles in some areas, and also blowing snow back over
roadways and prolonging dangerous travel conditions. In light of
this, have opted to replace much of the warning, generally from
around the Des Moines metro northward and eastward to our CWA
borders, with a Winter Weather Advisory for blowing snow until
noon today. As the low pressure system moves away to our east,
taking the tighter pressure gradient with it, winds will
gradually diminish from west to east this morning allowing the
blowing snow to abate and roads to be re-cleared.

Later today and tonight a surface high pressure area will slide
across Iowa, bringing nearly calm winds this evening and
supporting much colder temperatures. However, the temperature
forecast after sunset tonight is complicated by questions about
cloud cover, not only how much will persist from this morning
right through the day, but also how quickly high clouds will
move in from the west tonight ahead of the next storm system.
Have maintained a temperature forecast close to the previous
package for tonight, but short-term adjustments will likely be
needed based on observational trends.

Late tonight a broad 500 MB trough will swing southeastward over
the northern High Plains, and subsequently cross Iowa and the
Midwest from Monday to Monday night. While broad forcing for
ascent in the leading flank of the advancing trough will support
redevelopment of clouds and snow, there are significant
differences between this system and the one we experienced over
the last couple of days. It is substantially weaker in terms of
being an open trough rather than a deepening closed low. There
is little low-level reflection as the surface pressure pattern
will be loose and nebulous. Surface winds will remain light on
Monday, and moisture will be much more limited than the previous
system with QPF only about 10 percent of what fell the last two
days. All that being said, there are still potential impacts to
consider. A ribbon of pronounced frontogenetical forcing around
650 MB will help to focus the broader lift and generate a broad
band of snowfall roughly oriented from southwest to northeast,
but translating east northeastward across the region. Most
model solutions take this zone of snowfall across southern and
eastern Iowa during the day on Monday. In addition, forecast
soundings depict a very deep dendritic growth zone for much of
the event, although the transient band of frontogenetical
forcing is mostly located above the DGZ and not within it. Even
so, given the temperature profile and deep growth zone, snow-
to-liquid ratios will be considerably higher with the Monday
system. Thus while QPF is only 0.1-0.2 inches across our central
to southern counties, SLRs of 15 or 20 to one are anticipated,
resulting in potential snow accumulations of 2-4 inches. This
does not qualify as a winter storm by any stretch, particularly
with it being a relatively long duration accumulation and with
light winds. However, coming fast on the heels of the previous
heavy snow and on the first work/school day for many returning
from the Thanksgiving holiday break, impacts may exceed those
typical of such an event.

From late Monday night through the rest of the week the forecast
is generally quiet and cold. There is a low chance (around 20%)
of light snow Tuesday night into Wednesday, but it appears to be
low impact at this point. Thursday will be very cold with a
surface high pressure area moving through. Morning lows will be
well below zero, potentially around 10 below zero in the north,
and Thursday afternoon highs only in the low to mid-teens.
However, winds will be light during this time so wind chills
will likely not reach advisory criteria. Additional snow chances
return toward the end of the week, but are nebulous at this
range.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1138 AM CST Sun Nov 30 2025

MVFR stratus is beginning to give way to clear skies over
northern Iowa, while central and southern IA remain broken to
overcast around 1500 to 2000 ft. Brief flurries have been seen
under this stratus, but impacts have been isolated and
transient. There`s still some uncertainty on if stratus will
fill back in overnight, but it`s likely there will be gaps in
the deck leading to cigs fading in and out of MVFR. Have left
fog mention in over the north overnight, given the signal for
lower visibilities in guidance. That said, aside from light
winds and low pressure, dry low levels may inhibit fog. Will
continue to evaluate fog potential for tonight/Monday morning in
future issuances.

Light snow will move into southern Iowa early Monday morning and
persist through the day. This will likely impact KDSM and KOTM,
although snow as far north as KFOD and KALO can`t be ruled out.
visibilities under 2 miles and ceilings around 1000 ft looks to
accompany snowfall.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon CST today for IAZ007-017-
025>028-036>039-047>050-059>062-073>075.

&&

$$

DISCUSSION...Lee
AVIATION...Dodson