207
FXUS63 KDMX 281737
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1137 AM CST Fri Nov 28 2025

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

.KEY MESSAGES...

- Widespread heavy snowfall beginning late today into tonight
  and persisting through the day Saturday and into Saturday
  night. Total snowfall accumulations of generally 8 to 12"
  with higher amounts possible.

- Mostly dry forecast from Sunday onward, except for a chance of
  light snow around Monday. Much colder temperatures for much of
  the coming week, with lows near zero Monday morning.

&&

.DISCUSSION...
Issued at 257 AM CST Fri Nov 28 2025

     A major Winter Storm will affect most of Iowa from later
today and tonight through Saturday...

A potent 500 MB trough is coming ashore over the U.S. Pacific
Northwest coast at this time, and will quickly dive southeast and
deepen over the Rockies today, emerge over the High Plains tonight,
and become almost negatively tilted as it crosses Iowa Saturday
afternoon and evening. At the surface, a high press ridge is
currently building in from our west and will quickly cross Iowa this
morning, with strong cyclogenesis occurring in the lee of the
Rockies around southeastern Colorado this afternoon and evening. As
the large surface cyclone develops in response to the advancing 500
MB trough, it will stream moisture northward from the Gulf.
Initially, a ribbon of pronounced frontogenetical forcing associated
with the early development of the cyclone may generated some banded
snow over areas just to our west and southwest, but that component
of the forcing will fade out as the system approaches our area and
larger-scale isentropic lift dominates. At the 280K surface there is
good agreement that strong isentropic lift will continue for quite
some time, and combined with unseasonably high moisture content this
will promote a prolonged heavy snow event across most or all of our
forecast area before the system departs on Saturday night. This has
been well advertised and Winter Storm Warnings are already in effect
for the majority of the area.

New short-range model guidance continues to trend QPF slowly upward,
which in turn is slowly increasing forecast snowfall amounts. A
large swath of 10+ inch amounts is now forecast across much of Iowa,
excepting far southern and southwestern sections. The southern
extent of this higher snowfall amounts has also crept a bit farther
south overnight, necessitating a transition of the Winter Storm
Watch to a Warning for nearly our entire service area. The exception
is in our far southwest corner, where predicted snowfall amounts are
generally under 6 inches and the Watch has been transitioned to a
Winter Weather Advisory instead. At any rate, significant travel
impacts are anticipated from this system and travel across some
parts of the state will be nearly impossible at times, beginning by
tonight and especially on Saturday. Even into Saturday night,
some models depict a band of snow within the deformation zone on
the backside of the cyclone moving through our southeastern
counties, and light snow lingering farther northwest, so it is
likely travel conditions will not improve significantly until
around Sunday morning. Some minor adjustments were made to the
beginning time of Advisories/Warnings in southern Iowa, but the
end time for all headlines was maintained at 12Z Sunday to
account for these lingering travel impacts as the snow tapers
off Saturday night.

From Sunday onward the forecast is mostly dry, with some low/light
snow chances in southern Iowa on Monday but looking like a minimal
impact at this time. Of greater note is that it will be very cold
for multiple days, with highs mostly in the teens on Sunday and
Monday and essentially no highs above freezing forecast all week.
The fresh, deep snow pack will thus remain in place for an extended
period and promote the potential for efficient radiational cooling
when conditions favor it. The first such opportunity may come Sunday
evening/night as a surface high pressure area crosses Iowa bringing
very light to calm winds, however, there are indications that high
clouds may move overhead during that time in advance of the weak
Monday system so have not bitten off on lowering forecast temps for
Sunday night yet, and the current forecast is already near the
bottom of the guidance envelope. Either way it will be much colder
than we are used to, given the unusual warmth of most of the autumn
season.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1131 AM CST Fri Nov 28 2025

Currently, VFR conditions prevail over the area with mid-level
clouds streaming overhead. However, through the afternoon and
evening hours, the well-advertised snow storm will begin
impacting the state. This will be moving from west to east
through the evening, eventually spanning much of the area
overnight and into tomorrow morning. Reduced visibilities and
low clouds will accompany this snowfall. TAFs represent the
steadily worsening trends through the night, although more
localized bands of snowfall tonight and tomorrow could cause
abrupt drops in visibility and ceilings. Snow continues through
the day tomorrow, leading to low visibility and IFR or lower
ceilings through the end of this TAF period.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 3 PM this afternoon to 6 AM CST
Sunday for IAZ004-005-015-023>025-033>036-044>047-057>059-
070>072.
Winter Storm Warning from 6 PM this evening to 6 AM CST Sunday
for IAZ006-007-016-017-026>028-037>039-048>050-060>062-073>075-
082>085-094-095.
Winter Weather Advisory from 6 PM this evening to 6 AM CST
Sunday for IAZ081-092-093.
Winter Storm Warning from 9 PM this evening to 6 AM CST Sunday
for IAZ086-096-097.

&&

$$

DISCUSSION...Lee
AVIATION...Lee