FXUS63 KDMX 201733

Area Forecast Discussion
National Weather Service Des Moines IA
1133 AM CST Thu Jan 20 2022

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

.DISCUSSION.../Today through Wednesday/
Issued at 208 AM CST Thu Jan 20 2022

Key Messages:

- Very cold through today, tonight, and into Friday morning.
- Not as cold this weekend, but intermittent light snow chances
- Very cold again around Monday night into Wednesday next week.

As advertised, the Arctic dome has arrived with temperatures in
the process of falling below zero statewide early this morning,
and gusty northwest winds pushing wind chill values down into the
-20 to -30 across most of our forecast area. Wind Chill Advisory
 remains in effect for the entire area, and nearly the entire
 state, through this morning. As the high pressure center settles
 across Iowa later today and into tonight winds will go nearly
 calm, but temperatures will only climb into the single digits
 this afternoon, then plummet again after sunset this evening.
 Tricky forecast for temperatures and apparent temperatures
 tonight given the initially light nature of winds and potential
 for plunging temperatures after dark, but then slowly increasing
 winds late tonight/early Friday morning especially across the
 western half of Iowa. Given these uncertainties as well as the
 ongoing headline for the entire area, have opted not to issue an
 additional wind chill headline for tonight/Friday morning.
 However, it is anticipated one will be issued later today for at
 least a good portion of our forecast area, and in any event it
 will remain very cold tonight into Friday morning.

As the cold high pressure area moves away on Friday we will see a
return of modest southerly low-level flow but temperatures will
only rebound into the teens, perhaps lower 20s west, by the
afternoon. A series of shortwave impulses traveling through the
mid-level flow will then carve out a northwesterly steering
pattern aloft this weekend. While temperatures will not be as
cold, this regime will allow for multiple opportunities for light
snow. The first shot will accompany the leading shortwave trough
on Friday night, with a second round Saturday night and a third
around Sunday night into Monday. Each of these systems will be
quick moving and relatively weak in terms of its precipitation
potential, with only light snowfall accumulations expected mainly
across about the northeastern half of Iowa each time. Even so,
there may be some travel impacts in the form of slick roads,
mainly while the snow is falling, through this will be somewhat
mitigated by the nocturnal timing of the first two rounds. The
third, late Sunday night into Monday morning, again appears light
but will be accompanied by somewhat stronger northwesterly winds
and may also affect the Monday morning commute. Probability of
significant impacts is fairly low at this time given the light
QPF, but certainly worthy of keeping an eye on in the coming

A cold front sweeping across Iowa during the day on Monday will
put an end to precipitation chances for a few days afterward, but
will also be followed by another large Arctic high pressure center
and a corresponding cold snap from Monday night into Wednesday
morning, which appears eerily similar to the current cold event in
its synoptic evolution and duration. While details of
temperature/wind chill levels are not precise at this range, there
is certainly the potential for more cold headlines in the early to
middle part of next week.


.AVIATION.../For the 18Z TAFS through 18Z Friday afternoon/
Issued at 1125 AM CST Thu Jan 20 2022

VFR conditions are expected across the terminals through the
forecast period. Winds will shift southerly this evening,
becoming breezy into Friday morning.


Wind Chill Advisory until noon CST today for IAZ004>007-015>017-




NWS DMX Office Area Forecast Discussion