Marshalltown, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

568
FXUS63 KDMX 060845
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
245 AM CST Sat Dec 6 2025

.KEY MESSAGES...

- Accumulating snow across northern and central Iowa beginning
  this afternoon and ending before sunrise Sunday.
  Accumulations of 5-7+ inches expected across northern Iowa
  with lesser amounts into central Iowa.

- Colder on Sunday with highs in the single digits north to low
  20s south.

&&

.DISCUSSION...
Issued at 245 AM CST Sat Dec 6 2025

Stratus blankets Iowa early this morning except for a few
transient holes in the cloud cover. This has helped to keep
temperatures overnight fairly mild, at least in contrast to
recent nights, with temperatures in the mid 20s to mid 30s.
Cloud cover has also helped to keep fog development at bay. Mild
air over the colder snow pack would be a good combination for
fog development, especially with available low level moisture,
but clouds have helped to insulate enough to mitigate
development thus far. Patchy fog may still be possible later
this morning where there are holes in the stratus or near the
edges.

If we zoom out on satellite from the view of the stratus across Iowa
we see the development of the system set to impact the area later
today. Surface low pressure is developing across Wyoming into South
Dakota as the upper level embedded shortwave drops south. The low
will pass across Nebraska through the morning with the center
expected to track across Missouri this evening and overnight
before lifting east. The northern deformation zone will pass
across Iowa, bringing a band of accumulating snow to the area.
Snow is expected to begin in western Iowa around noon and
continue to expand across the area through the afternoon. Snow
will continue through the evening, tapering off before sunrise
on Sunday morning. Snow rates of 1"/hr are possible per HREF
guidance across northern Iowa, where omega is maximized through
the dendritic growth zone for several hours. As in the past few
runs, Cobb tables continue to suggest snow to liquid ratios of
15-20:1 through the event, with higher ratios towards the tail
end. Accumulations of 5-7+" are expected within the heaviest
band which is currently forecast across northern Iowa. Even at
this time with onset in the next 12-18 hours, there remains
notable spread amongst guidance on where this band will setup.
High resolution solutions from the HRRR/RAP favor far northern
Iowa while the GFS is further south towards central Iowa. The
Euro remains between the two, along with the most recent NAM
run. Respective ensemble members of the GFS and Euro suites
generally mirror the deterministics, though there is notable
spread there as well. Have expanded the Winter Storm Warning by
a few counties in the north to account for the northern lean to
current guidance. Across southern Iowa temperatures will be near
to a few degrees above freezing, allowing for a rain/snow mix.
A few model soundings show a brief period with a mid level dry
layer with lack of ice introduction which could result in
freezing drizzle. This signal is fairly transient and do not
expect much notable impact, but will be worth monitoring in case
it becomes more consistent.

Colder air pushes into the area behind the system on Sunday with
highs in the single digits north to low 20s south. Soundings
have 20- 25 kts through the mixed layer and gusts at the surface
of 20-25 mph are possible on Sunday. With the lighter, fluffy
snow type expected some minor blowing is possible but impacts to
visibility should be fairly limited.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1112 PM CST Fri Dec 5 2025

MVFR cigs continue to shroud much of Iowa late this evening. A
few pockets of VFR conditions exist but they are few and far
between. MVFR conditions are likely to continue until snow
reaches central IA mid afternoon with conditions deteriorating
to IFR. LIFR conditions could accompany the heaviest snow across
northern IA early Saturday evening.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from noon today to midnight CST tonight
for IAZ004>006-015-016-023>025-035-036.
Winter Storm Warning from 3 PM this afternoon to 6 AM CST
Sunday for IAZ007-017-026>028-037>039.
Winter Weather Advisory from noon today to midnight CST
tonight for IAZ033-034-044>047-057>059-071-072.
Winter Weather Advisory from 3 PM this afternoon to 6 AM CST
Sunday for IAZ048>050-060>062-073>075.

&&

$$

DISCUSSION...Hagenhoff
AVIATION...Borghoff