767
FXUS63 KDMX 010500
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1100 PM CST Wed Dec 31 2025

 ...Updated for the 06z Aviation Discussion...

.KEY MESSAGES...

- Light wintry precipitation possible this afternoon and early
  this evening from around Mason City to Waterloo and more so
  points northeast of this area. Potential accumulations of a
  light glaze of ice or dusting of snow.

- Colder on New Year`s Day, but temperatures moderating to above
  normal by Sunday into next week with mainly dry conditions

&&

.DISCUSSION...
Issued at 137 PM CST Wed Dec 31 2025

Upper level GOES-East water vapor imagery shows a ridge over
the western CONUS with a closed low off of the California coast
that will slowly move eastward through the end of this week.
There is a plume of moisture flowing over top of this ridge and
into our region in the fast, 130 knot 250mb northwesterly flow.
A shortwave trough can easily be seen in this imagery and is
just northeast of Lake Superior. A surface cold front is
trailing back to its west and is the feature of interest for our
potential light wintry precipitation over our northeastern
forecast area from around Mason City to Waterloo this afternoon
into early this evening. However, there are several forecast
parameters that are marginal and bring into question whether it
will occur. First, the ice introduction layer may or may not
have saturate, depending on the model, though it can be stated
with confidence that there is a gradient in ice
introduction/drier air over the same Mason City to Waterloo
area. If ice introduction is achieved, then flurries or light
snow would result, which seems to fit with current surface
observations, mPINGs, and reported road conditions in Minnesota.
If there is no ice introduction, then freezing drizzle may
result. Forecast soundings show that saturation is elevated
above the surface and around a 1km in depth for a few hours at
most. While low and mid- level thermodynamics and upper level
kinematics are favorable for lift, the saturated layer shows a
lack of lift with neutral to weak subsidence in forecast
soundings. Lastly, there is some degree of wind shear, but that
becomes more unidirectional as the boundary moves through the
area. Therefore, have trimmed back areal extent of freezing
drizzle mentioned in the forecast with updates this morning and
have maintained that thinking and forecast into this afternoon.
Any icing, if it were to occur, would be a hundreth or two as
drier air pushes in and dries out the column.

As the cold front clears the state tonight, temperatures will fall
into the single digits and teens above zero by New Year`s Day
morning. Another subtle, fast moving shortwave will slip into and
through the region on Thursday, but the moisture profiles are
insufficient with lots of dry air in the mid-levels for any snow
over our forecast area. The jet stream and shortwave trough train
will trek a bit farther northeast through the first weekend of 2026,
though the aforementioned closed low off the California coast will
slide across into the central or southern Plains. Moisture return
this far north looks unlikely so not expecting any significant
precipitation through the weekend as temperatures moderate to normal
by Saturday and above normal by Sunday. The West Coast ridge axis
pushes over the central US early next week while at the same time
deamplifying, which may allow the jet stream to bring light
precipitation chances closer to the northern border of the state. As
the the flow becomes more southwesterly late in the week, this
presents a more opportune setup for precipitation and something to
watch in the coming days.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1100 PM CST Wed Dec 31 2025

The low stratus clouds that moved through the area this evening
are largely clearing into southern Iowa, but MVFR ceilings
generally between FL011 and FL018 will still sporadically affect
the terminals in the next several hours before ending.
Thereafter, VFR conditions will prevail through the remainder of
the overnight and Thursday morning. There is some potential that
the low clouds may return as low-level flow becomes light
southwesterly on Thursday then goes light and variable, however,
confidence in how widespread any such returning clouds will be
or what the associated ceiling heights would be is low, so will
advertise VFR ceilings at FL035 in the 06Z TAFs and monitor
short-term forecast trends for adjustments in subsequent TAF
issuances.

&&

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

&&

$$

DISCUSSION...Ansorge
AVIATION...Lee