858
FXUS63 KDMX 162336
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
536 PM CST Sun Nov 16 2025

 ...Updated for the 00z Aviation Discussion...

.KEY MESSAGES...

- Cool and dry with increasing clouds tonight into Monday

- Breezy on Monday. Rain chances increasing through the
  afternoon, with a few rumbles of thunder possible south. Snow
  may mix in with rain in the north.

- Slight warming through mid-week

&&

.DISCUSSION...
Issued at 243 PM CST Sun Nov 16 2025

<< DRY AND MILD TODAY, PRECIPITATION RETURNING THIS WEEK >>

Quiet and mild conditions are in place over the state today, as
surface high pressure dominates the pattern. Cloud cover has slowly
increased from the west, but is struggling as it moves into the very
dry airmass over Iowa. These clouds will eventually span much of the
area, which combined with increasing winds, should help keep
temperatures from plummeting tonight. The increasing winds tonight
and breezy conditions on Monday will be indicative of the tightening
pressure gradient in response to lee-side cyclogenesis in the
plains. This cyclogenesis is coincident with the PV anomaly that is
now making it`s way through the Rockies, which will eventually track
through Iowa and bring our next chances for precipitation late
Monday into early Tuesday.


<< MONDAY/TUESDAY SYSTEM: MOSTLY RAIN, BUT SOME THUNDER AND SNOW? >>

As the wave passes across the plains tomorrow, a strong push of
theta-e advection will lift into the area. The associated plume of
low and mid-level moisture will work to saturate through the dry
antecedent air mass, eventually saturating down to the surface
through late Monday afternoon and evening. Precipitation will
increase in likelihood farther north and east in Iowa, although
occasional rain/showers are possible throughout the area Monday
afternoon and evening. A stout warm nose in the mid-levels will keep
precipitation as mostly rain over central and southern Iowa. With
this warm nose in place, lapse rates even steepen enough to
produce some instability aloft, introducing the potential for a
few rumbles of thunder as rain moves through. This will be most
likely in the southern half of the forecast area where
instability values could approach 200 to 300 J/kg, depending on
the model you pick. Any convectively driven parcels would be
rooted quite a ways aloft, but with the cold profiles, can`t
rule out some small hail, which this time of year may perceived
as sleet, although the processes for creating the two types of
ice pellets does differ.

The precipitation forecast becomes a bit trickier over northern Iowa
where colder air and stronger forcing will bring potential for
wintry precipitation Monday night into Tuesday. Along and just north
of the Iowa/Minnesota border, a band of stronger frontogenetical
forcing will set up in the 800 mb to 700 mb layer generating strong
lift up into the dendritic growth zone. The warm nose aloft is
coming in a bit weaker with today`s guidance as well, resulting in a
temperature profile nearly isothermal along the 0 C isotherm
once saturation occurs. Surface temperatures and wet bulbs are
still forecast to be above freezing, but if that stronger
forcing leaks into far northern Iowa, it`s possible the shallow
surface warm layer won`t be able to melt the volume of snow
falling into it. If these heavier rates come to fruition, areas
in northern Iowa could pick up a quick inch or two of snow
Monday night/Tuesday morning. Of course, if this better forcing
sets up north of the area, or the warm nose is a few degrees too
warm, precipitation would fall as a cold rain instead. Right
now, the expectation is still that the bulk of the snow is going
to stay to our north. Mostly rain will fall in our forecast
area, with occasional snowflakes mixed in along the northern
border. If a change over to snow does occur and we see
accumulations south of the Iowa/Minnesota border, deterministic
and ensemble guidance both suggest it would be most likely in
areas north of highway 18. Even then, recent warm conditions
should have ground temperatures warm enough to melt the snow as
it falls, further reducing any accumulations.

Through early Tuesday morning, deeper saturation will fade in and
out as drier air works into the mid and upper levels, reducing ice
introduction. Low level saturation will stick around through the
morning hours, keeping low clouds. Brief drizzle may still be
possible through the morning on Tuesday, but a relative lack of lift
in the low levels is going to be working these chances. Likewise,
the saturated layer isn`t looking nearly as deep as it did in
soundings yesterday, further diminishing the potential. Like with
the snow, if drizzle does occur, surface and ground temperatures
should be warm enough to negate significant freezing in northern
Iowa.


<< REST OF WEEK, THURSDAY/FRIDAY SYSTEMS >>

Although they may not be as supportive for drizzle, saturation in
the low levels will keep low cloud cover overhead through much of
Tuesday, keeping temperatures cool through the day. For this reason,
have knocked high temperatures down a few degrees on Tuesday as
guidance is likely too aggressive with mixing out the boundary layer
given the cloud cover and CAA. By Wednesday, return flow develops on
the back side of the Great Lakes high, bringing warmer temperatures
through the middle of the week. By Thursday, two 500 mb waves will
pass through the central US and Canada, influencing the weather
through the second half of the week. How these two waves interact
will be worth watching, as the GFS brings the northern wave far
enough south to keep the southern wave suppressed and the
precipitation south of Iowa, while the ECMWF shows the southern wave
lifting up into southern Iowa, bringing widespread rain chances to
Iowa on Friday. More on these systems in the coming days.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 535 PM CST Sun Nov 16 2025

Mid-level clouds remain over much of the area this evening,
though should depart tonight with upper level clouds largely
remaining overhead into Monday. Then, more widespread mid-level
clouds, and eventually low VFR cloud cover is expected to move
eastward overhead by Monday afternoon. This will also lead to
rain chances mainly after 20z for most sites, which are handled
with PROB30 mentions at this time given the lower certainty on
exact timing and coverage of this rainfall. Thunder is also
possible at KDSM and KOTM late in the period, though confidence
is far too low to include at this time. Will update as needed
given trends and overall confidence over the next few issuances.
Winds light and variable will gradually prevail out of the
southeast tonight, turning breezy through the morning to
afternoon with gusts up to 20-25 knots.

&&

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

&&

$$

DISCUSSION...Dodson
AVIATION...Bury