980
FXUS63 KDMX 161124
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
524 AM CST Sun Nov 16 2025

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

.KEY MESSAGES...

- Cooler with a few passing clouds today.

- Increasing clouds and precipitation chances Monday with the
  clouds persisting into Tuesday.

&&

.UPDATE...
Issued at 408 AM CST Sun Nov 16 2025

High pressure is moving into Iowa early this morning. The dry air
associated with the system is around 5 kft deep while moisture above
this height has resulted in a band of mid-level cloudiness over
parts of central and northwest Iowa. The high will slowly migrate
east through tonight. The closed upper low over southern California
remains the main weather story for Iowa through mid-week. While this
system will fragment today, a strong piece of energy that is
rounding the trough portion of the system will eject out towards the
state later today and tonight. As this occurs, the Gulf moisture
stream will begin to lift back north in the wake of the departing
high leading to increasing cloudiness first on Monday followed by
increasing precipitation chances in the afternoon and night.

Little change in the overall progression of this system from what we
have been highlighting the past several days. A quick recap is
saturation will occur from top down so aloft first while dry low
level air continues to be reinforced by the high to the east.
Saturation will occur and will result in cooling of the column as
temperatures drop closer to the wet-bulb temperatures. The main
uncertainty that remains here is if enough cooling occurs for a
transition to snow over northern/northeastern Iowa. It will be close
though the general consensus is just enough warm air aloft will
remain for mostly rain. The timing of the kinematic forcing arriving
Monday night with the PV anomaly track better defined and moving
over central Iowa by 12z Tuesday. Subsidence and mid-level drying
will follow behind the system while the Saturation in the lowest
5000 ft remains. Ice introduction is lost at this point and while
there could be spotty drizzle, neutral forcing within this saturated
layer will limit collision coalescence. High temperatures for Monday
and Tuesday remain on the warm side but plan to continue to lower
these as widespread cloud cover and that model over mixing bias,
especially in the cool season months is resulting in highs that are
too warm.

&&

.DISCUSSION...
Issued at 156 PM CST Sat Nov 15 2025


<< WARM & BREEZY TODAY, COOLER & CALM SUNDAY >>

The surface cold front has made most of it`s way through the state
today, with the secondary trough just now entering northern Iowa.
This will continue to drop southward as the surface low over the
Great Lakes region keeps on eastward and surface high currently over
Montana and the Dakotas begins to fill in over the state tonight.
With the tighter pressure gradients and cold air advection in place
overhead, breezy winds are expected to persist this afternoon and
evening. Gusts of 20 to 25 mph are expected, with a few areas in
northeastern Iowa gusting near 30 mph this afternoon.

Gusts will diminish tonight as the surface decouples and the
pressure gradient lessens, but sustained winds will remain around 5
to 10 mph through roughly midnight. However, as the high pressure
continues to push in overhead, winds will fall to around and below 5
mph into the morning hours, especially west. Calmer winds in
conjunction with the drier dewpoints, could allow for efficient
radiational cooling overnight, but will be dependent on skies
remaining clear as well. A deck of low level clouds will move in
with the high, mainly impacting western Iowa, likely keeping low
temperatures from plummeting beneath. It will be areas on the
eastern fringe of this cloud deck, where winds are still light but
skies are clear, that could see temperatures drop rapidly on Sunday
morning. High pressure then dictates the weather on Sunday, with
partly cloudy skies, light winds, and mild temperatures in the 40s
and 50s.


<< MONDAY NIGHT RAIN, DRIZZLE POTENTIAL >>

The high pressure and quiet conditions on Sunday will be short-
lived, as 500 mb ridging develops ahead of an approaching shortwave
on Monday. As mentioned in prior discussions, this lobe of
energy will originate from the closed 500 mb low currently off
the coast of California, which is producing wet, soggy
conditions for our friends from eastern Iowa currently visiting
Los Angeles Memorial Stadium. As this system makes it`s way onto
the main land, it splits into two shortwaves, one of which
tracks northward through the Rockies and the other more east
northeastward across the Rockies, through the Plains and
eventually into Iowa. This system will bring the return of
precipitation chances to the area, mostly in the form of rain
for our forecast area. With the system trending more dynamic and
slightly farther north, warmer air is being pulled up into the
state, keeping temperatures warm enough to negate snowfall,
aside from far northern Iowa. However, even in northern and
northeastern Iowa where low level temperatures are cooler, both
deterministic and ensemble soundings show a persistent warm nose
around 2 to 4 C that will work to melt any snowflakes that fall
through it. There could be an occasional wintry mix as the
profiles saturate and cool, as melted snow refreezes below the
warm layer, but even then current soundings would still favor a
cold rain over frozen precipitation.

Rain chances look to be most likely along the initial wing of
increasing theta-e and as the low level moisture phases with the
upper level moisture. This will be occurring late Monday into early
Tuesday. However, while the phasing of the two moisture streams
seems fairly limited in time and space on Monday night, there also
looks to be a strong push of low level moisture with a 1 to 2 km
saturated layer showing up at times in model soundings. Although
lift isnt great through this saturated layer, this would imply the
potential for occasional drizzle throughout central Iowa
overnight Monday into Tuesday morning. With the warmer trend,
surface temperatures should remain above freezing in most areas,
but a few degrees cooler in northern Iowa could lead to some
freezing drizzle potential on Tuesday morning.


<< WORK WEEK FORECAST >>
The forecast will be relatively active through the rest of next
week, with a brief break from precipitation during the day
Wednesday. However, a southern stream 500 mb trough builds in
the western CONUS before lifting northward into the midwest,
bringing another potential for precipitation late Wednesday
through Thursday and Friday. Early indications suggest mostly
rain with this system, as the colder air is wrapped up in a
northern stream wave passing through Canada. However, this is
still over 5 days out, so will want to watch how these southern
and northern stream troughs interact and for any trend toward
colder temperatures, especially wrapping around the backside of
the southern stream wave.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 522 AM CST Sun Nov 16 2025

VFR conditions through the period with light northerly wind
today transitioning to east/southeast this evening. Increasing
mid-level cloudiness later today and overnight with cigs at
5-6 kft common.

&&

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

&&

$$

UPDATE...Donavon
DISCUSSION...Dodson
AVIATION...Donavon