017
FXUS63 KDMX 202040
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
240 PM CST Thu Nov 20 2025

.KEY MESSAGES...

- Stratus and patchy fog lingers today. Potential for more fog
  in southern Iowa tonight.

- Rain possible along the Iowa/Missouri border through Friday.

- Mild and pleasant conditions this weekend.

- Rain returns Monday, then trending colder through the end of
  next week.

&&

.DISCUSSION...
Issued at 237 PM CST Thu Nov 20 2025

The perpetual stratus and fog continues, as we once again saw a
morning of moist, foggy conditions with overcast skies. Today`s
stratus deck actually originates from a slightly different
source than yesterdays. The boundary that moved through this
morning flipped winds more northerly, and brought another slug
of moisture and stratus down and pushing yesterday`s stratus
deck to the east. There is a brief hole in the clouds over
southern Iowa, where the new stratus deck hasn`t arrived and the
old stratus deck has departed, but this will fill in through
the afternoon. This secondary stratus deck isn`t as prominent as
yesterday`s with patches of more partly cloudy skies being seen
upstream over southern Minnesota and southeast South Dakota,
and clear skies farther northeast than that. This dry slot will
be slowly chipping away at the stratus through tonight. That
said, while low clouds will begin to lift and erode over
northern Iowa tonight, mid and upper level clouds will will
continue to fill in from the south, resulting in mostly cloudy
conditions on Friday. Farther south in the area, the moist low
level air will still be in place again overnight, resulting in
another night/morning of fog potential. This will generally be
south of highway 30, but will depend on how quickly the dry air
works into the area.

As alluded to earlier, mid and upper level clouds will begin to move
in from the south as a southern stream wave lifts toward the area. A
fairly stout stream of moisture will accompany this wave, but will
meet the cooler, drier air mass currently moving into the state.
This will limit rain chances in Iowa, as the drier mid-level air
from the north undercuts the saturated layer from the south. The net
result is a more southerly trend in precipitation chances, with most
of the rainfall on Friday being limited to areas along and south of
the Iowa/Missouri border. It`s possible light rain/sprinkles squeeze
through farther north into central Iowa, but forecast soundings
don`t look overly promising with the stout dry layer around 925 mb
to 850 mb. As a result, have trimmed down the northern extent of
precipitation chances on Friday, but maintained the higher chances
along the southern border.

High pressure takes over on Saturday and skies finally begin to
clear out. Temperatures will be seasonably warm, with highs in the
mid to upper 50s on both Saturday and Sunday, making for a pleasant
fall weekend, especially for this late in November. You`ll
definitely want to take advantage of the mild weekend, because the
pattern takes a colder turn through next week. First, it looks like
another southern stream system will lift up toward the state on
Monday, bringing more rain chances to the area through the day. Once
this southern stream wave lifts, it will merge into the broader 500
mb pattern, ending our prolonged period of split flow. The northern
stream then takes over as the dominant pattern, allowing the a
canadian long-wave trough to dive southward into the central US
Tuesday into Wendesday. Cooler temperatures will be pulled down on
the backside of this system, dropping our temperatures considerably
through the second half of the week. Current 7-day forecast has
highs only reaching the mid to upper 30s Wednesday and Thursday,
although this will likely fluctuate through the coming days.

There has also been quite a bit of interest in precipitation
forecasts through Thanksgiving, particularly in terms of snow.
As of right now, there isn`t an overly consistent signal for
snow in the deterministic models. With the departing trough and
pockets of energy orbiting it, it`s not out of the realm of
possibility we could see some precipitation development through
the end of next week. Likewise, a transition to a more northwest
flow pattern opens up the possibility for subtle waves of
energy to kick off some precipitation. This potential for a more
agitated pattern combined with cooler temperatures certainly
opens up the possibility for snow. However, at this time range
and with such subtle features, it`s extremely difficult to
reliably forecast snowfall. Therefore, stay tuned to the
forecast through this weekend and into early next week, as
details around the Thanksgiving weekend become more clear.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1131 AM CST Thu Nov 20 2025

Fog and stratus around 200 to 500 ft continues over the area
today, although visibilities are improving. Fog will continue to
improve today. Expecting this stratus to stick around through
most of the afternoon and evening, although ceilings should lift
a few hundred feet as the afternoon progresses, before falling
again tonight. Therefore, mostly IFR conditions prevail at
southern sites (KDSM and KOTM) while northern sites (KFOD, KMCW,
and KALO) could see some periods of MVFR as drier air works in
from the north. Additional fog development is possible again
tonight and into Friday morning, but haven`t included visibility
restrictions in TAFs yet due to low confidence in location. Low
clouds stick around through this TAF period, with improvement
beyond this period through Friday afternoon and evening.

In addition to clouds and visibilities, light winds are steadily
transitioning to more west then northwesterly behind the
boundary today.

&&

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

&&

$$

DISCUSSION...Dodson
AVIATION...Dodson