038
FXUS63 KDMX 281140
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
540 AM CST Wed Jan 28 2026

 ...Updated for the 12z Aviation Discussion...

.KEY MESSAGES...

- Very light snow chances (20%) in southwest Iowa Thursday.

- Final push of cold air into Friday with highs in the single
  digits to low teens, then warming into next week.

- Light snow accumulation Saturday night and through the day Sunday.

&&

.UPDATE...
Issued at 225 AM CST Wed Jan 28 2026

A broad area of stratus is moving across the southwest half of Iowa
early this morning. This has kept temperatures there in the mid to
upper teens while cloud free areas have fallen to near 0. Stratus
will continue to slide across the southwest to central portions of
Iowa through today. While a few flurries may fall out of the
stratus, very dry mid and low levels will preclude much in the way
of precipitation. With weak warm air advection into southwest Iowa
today temperatures will warm into the mid 20s while the rest of
Iowa remains in the teens and single digits. Similar conditions
are expected on Thursday, however with better upper level
support there is a chance for light snow in southwest Iowa.
Another lobe of vorticity will rotate around the larger
northeast US low and move across the area. There is a modest
increase in mid level moisture in southwest Iowa which may help
with very light snow development, however dry air will remain a
challenge. Lapse rates do steepen, however soundings and cross
sections show very little omega and modest low level
frontogenesis so anything that does develop will be light and
short lived. Another shot of arctic air will push across the
area on Friday with highs back to the single digits and low
teens.

&&

.DISCUSSION...
Issued at 211 PM CST Tue Jan 27 2026

A large 500 MB gyre is spinning over Hudson Bay and northern
Ontario, with a series of shortwave impulses rounding its base
over the Upper Midwest and Great Lakes regions. One such
impulse scraped northeastern Iowa last night, and the next one
will move from southern Canada into Minnesota this afternoon
and Wisconsin tonight. As it does so, any associated clouds and
precipitation will remain well to our northeast but a surface
high pressure ridge over the Dakotas will be induced to build
southeastward toward Iowa. By Wednesday evening we will be
within the influence of this ridge, while farther west a broad
low pressure trough will develop over the lee of the Colorado
Rockies. On Wednesday night and Thursday this surface low will
slide southeastward through Kansas and eventually into Arkansas.
As it does so, a swath of modest frontogenetical forcing and
warm air advection aloft will produce a broad band of light snow
extending from northwest to southeast down the High Plains.
Some model solutions paint light QPF in our southwestern
counties in association with this band, however others keep the
light snow farther southwest of our area, and forecast soundings
indicate that low-level dry air entrainment out of the surface
ridge will undercut any snow and result in either no
precipitation or flurries. Have maintained low (10%) PoPs in our
southwest accordingly, and even if any snow does reach the
surface it should have no discernible impact.

On Thursday the 500 mb gyre over Ontario will begin to elongate
as it interacts with one last shortwave rounding its western
flank. There is strong model agreement that this evolution will
result in an east-west oriented longwave trough stretching from
Upper New England across the Great Lakes and over Minnesota by
Friday morning. As this trough then progresses southward Friday
and Friday night, it will initially push a larger, colder
surface high pressure area down across the region bringing lower
temperatures again at the end of the week. Friday *high*
temperatures are currently forecast only in the single digits
across northern Iowa and low to mid-teens in the south. On the
back/northern flank of the 500 MB trough, low clouds and light
snow will then spread southward through the region around Friday
night or so, however, current expectations are that this will
remain east of our area closer to the Chicago region, and our
forecast remains dry for now.

The 500 MB trough will move quickly away into the southeastern
U.S. this weekend, while two intertwined shortwaves scoot down
the High Plains and near Iowa by the latter part of the weekend.
Initially, from Saturday into Saturday night, the aforementioned
large high pressure area will sink directly over Iowa providing
dry and quiet but cold weather, with Saturday morning lows near
or below zero across our entire forecast area. As the
intertwined shortwaves then move overhead around Sunday or
Sunday night, they will bring chances for light snow across
Iowa. Currently the official forecast carries 40-50% chances
during this time, however, the overall probability of snow is
likely higher (60-80%), but is reduced by a large degree of
uncertainty in the timing and placement of the snow, due to the
complex interaction of the double-pronged system. At any rate,
there is a good chance of light snow in the latter half of the
weekend, but its orientation and relatively quick movement
mitigate any threat of heavy snowfall, and surface patterns do
not favor strong winds. Even so, any accumulating snowfall can
cause travel impacts, so we will be monitoring this potential in
the coming days.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 540 AM CST Wed Jan 28 2026

VFR conditions will persist through the period. A broad, mid
level stratus deck will move across the southwest half of Iowa
through today. This will skim sites KFOD/KDSM/KOTM much of today
resulting in fluctuations in VFR sky coverage. Winds today shift
from out of the west this morning to out of the north to
northeast by the end of the period Thursday morning.

&&

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

&&

$$

UPDATE...Hagenhoff
DISCUSSION...Lee
AVIATION...Hagenhoff