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FXUS63 KDMX 190820
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
220 AM CST Mon Jan 19 2026

.KEY MESSAGES...

- Very cold this morning, with winds only slowly diminishing.
  Wind chill values in the -20 to -30 range across much of the
  area before noon. Cold Weather Advisory remains in effect.

- Cooler temperatures continue Monday, then warmer on Tuesday.
  Snow chances increasing around Tuesday evening/night (now
  70-90% north and northeast), with light to locally moderate
  accumulations possible.

- Strong Arctic airmass to surge in later this week, with very
  cold temperatures around Friday-Saturday. Low temperatures
  Saturday morning will be well below zero statewide, and may
  approach -20 degrees in some northern/northeastern areas.

&&

.DISCUSSION...
Issued at 220 AM CST Mon Jan 19 2026

Broadly cyclonic 500 MB flow will continue to dominate our
region for the next week, with a series of troughs moving
overhead through this flow and providing periodic changes to our
sensible weather. One such trough slid by over northeastern Iowa
Sunday night, providing snow showers and supporting strong
surface winds that are abating very slowly early this morning as
the system moves away. Snow showers have ended for the most
part, with only isolated flurries lingering in our forecast
area, and blowing snow will gradually diminish with the winds
this morning. Meanwhile, it is very cold with temperatures
already below zero in our northern counties and in the single
digits central and south. Wind chill values of -20 to -30 are
occurring and expected across the bulk of the area and the
ongoing Cold Weather Advisory remains in effect. Even this
afternoon temperatures will only climb into the single digits
northeast to mid teens southwest, then tonight a surface high
pressure area will move quickly over Iowa providing light winds
and mostly clear skies that will allow temperatures to fall
rapidly after sunset. Have lowered Tuesday morning minimum
temperatures a bit accordingly, to near this morning`s levels,
however with light winds on Tuesday another advisory is not
anticipated.

The next 500 MB trough will move quickly down the northern High
Plains on Tuesday and cross Iowa Tuesday night. Ahead of this
system, on Tuesday, surface winds will come around to south
southeast in most of Iowa as the early morning high pressure
area quickly departs to our east. A surface low pressure trough
will develop from eastern Colorado up into central Nebraska by
Tuesday afternoon, in response to the approaching mid-level
trough, with an effective warm front setting up somewhere near
southeastern South Dakota and the Iowa/Minnesota border. This
will provide a focus mechanism for snow generation late in the
day Tuesday, then as the 500 MB trough moves through Tuesday
night it will pull the strengthening surface trough/low through
it, with the snow spreading southeast and wrapping into the
surface low. Ribbons of frontogenetical forcing, most pronounced
between 850-700 MB, will maximize residence time in our
northern and northeastern counties as they pivot in behind the
low traversing the state. Forecast soundings and vertical
cross-sections in this area, around Mason City and Waterloo,
depict multiple hours of deep saturation with modest but
persistent forcing for ascent near the Dendritic Growth Zone,
supporting relatively high snow-to-liquid ratios. In light of
these forecast trends, have increased POPs around Tuesday
evening to 70-90% in our northern and northeastern counties.
While associated snowfall amounts may be mitigated by the quick
passage of the synoptic system, snow may fall efficiently for a
few hours and produce a quick few inches in some areas. While
winds will be light Tuesday evening, perhaps 5-10 MPH, this
scenario would still result in some travel impacts and the
Tuesday evening timeframe will be closely monitored today
through tomorrow for further forecast adjustments.

Hot on the heels of the Tuesday night system, another 500 MB
shortwave will move over northern Iowa and Minnesota late on
Wednesday. This wave will be somewhat weaker however and with
less available moisture, so less precipitation is anticipated.
Even so, 20-30% POPs are carried north of Highway 30 around
Wednesday afternoon and could be expanded later in a "high POP,
low QPF" scenario. After this wave moves by we are in store for
a quieter few days, however, the parent 500 MB gyre responsible
for all this cyclonic flow, which will initially be swirling
around Hudson Bay early this week, will eventually pivot out and
swing southward, finally reaching southern Ontario and Quebec
later in the week. As it does so, it will push an arctic cold
front through the Midwest around Thursday or so, with a large,
very cold surface high pressure area from Canada spilling in
behind the front and dominating our weather at the end of the
week. It is possible we could see some very light snow as the
front moves through Thursday-ish, but the bigger concern will be
the much colder air filtering in afterward as the surface high
crosses Iowa from Friday into Saturday. With increasing
confidence in this scenario over the last day or so, consensus
model guidance for temperatures has really bottomed out, with
forecast *highs* on both Friday and Saturday now only in the
single digits above zero south to single digits below zero
north, and low temperatures Friday night/Saturday morning far
below zero across all of Iowa, and perhaps reaching -20 degrees
in some northern/northeastern areas. Yikes. While winds will be
relatively light with the surface high nearby, cold at these
levels still poses health risks to those outside, and if these
forecast trends hold then more cold weather advisories could be
needed later this week.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1010 PM CST Sun Jan 18 2026

Narrow bands of shallow clouds often containing snow showers
continue to move over northern Iowa late this evening. These
will continue to have intermittent impacts at FOD, MCW, and
ALO and have opted to prevail VFR with TEMPO restrictions as
these move over and away from a terminal. Otherwise, blowing
snow may continue over these sites as gusty winds slowly
subside overnight and through the day Monday. These shallow
clouds will slowly erode overnight into Monday with ceilings
generally expected to improve into VFR with moderate to high
confidence.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Cold Weather Advisory until noon CST today for IAZ004>007-
015>017-023>028-033>039-045>050-058>062-072>075-083>086-
095>097.

&&

$$

DISCUSSION...Lee
AVIATION...Ansorge