West Des Moines, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

639
FXUS63 KDMX 162021
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
221 PM CST Tue Dec 16 2025

.KEY MESSAGES...

- Snow melt continues with mild temperatures once again
  Wednesday, especially in the southwestern half of Iowa. Fog
  will be possible early Wednesday morning.

- Light rain will move through late Wednesday night/early
  Thursday morning, followed by a brief dry period later
  Thursday morning.

- Around Thursday afternoon a sharp cold front will push
  through, bringing strong and gusty winds, falling
  temperatures, and scattered snow showers. Travel impacts will
  be possible.

&&

.DISCUSSION...
Issued at 221 AM CST Tue Dec 16 2025

Modest southwesterly surface flow has helped temperatures rise
significantly today, remaining in the mid-30s in our
northeastern counties but soaring well into the 40s in central
and southwestern Iowa as the edge of the snow pack is steadily
eroded away. This renews the possibility of fog development
later tonight into Wednesday morning. However, fog was more
limited than anticipated last night/this morning, and tonight
there will initially be thicker cirrus clouds this evening,
after which winds will become northwesterly and promote
advection of lower dewpoints over the snow cover. Around and
after sunrise Wednesday a weak surface ridge will ooze across
Iowa and winds may go calm for a few hours so there is a brief
window of opportunity for some fog then, and have added patchy
wording to the forecast. Also worth noting is that after sunset
tonight, temperatures will once again fall well below freezing
in areas where snow is melting today, so there could be some
localized re-freezing especially on bridges and elevated
surfaces.

On Wednesday the aforementioned surface ridge will move away
and south southeasterly flow will quickly return and strengthen
by the afternoon. This will promote mild temperatures once
again, with highs similar to today, with additional melting of
the snow pack. It is likely that in areas of currently shallower
snow cover it will entirely melt by the end of the day
Wednesday, while in areas of deeper cover some of it will remain
in place at that time. However, as south breezes persist
Wednesday evening/early Wednesday night they will continue to
pump higher dewpoints into the area and prevent temperatures
from falling below freezing, so the snow melt will continue even
after dark and despite the gusty winds, some light fog may
develop as a result. Meanwhile, a 500 MB trough/low near the
eastern Montana/Canada border Wednesday evening will deepen and
move quickly southeastward Wednesday night, centering somewhere
near western/southwestern Minnesota by sunrise Thursday. As
this system approaches Iowa, two surface troughs will develop
around its southern periphery. The first will move through our
forecast area late Wednesday night, mainly between midnight and
sunrise Thursday, and will be accompanied by a swath of light
precipitation resulting from a combination of warm air/moisture
advection, low-level convergence, and broad lift associated with
the leading flank of the mid/upper level low. Forecast soundings
support light rain as the dominant precipitation type during
this time, and this will further aid in the ongoing snow melt.
All in all Wednesday night into early Thursday morning will be
damp and dreary.

The primary potential for hazardous weather in the next seven days
is focused on Thursday. Behind the leading trough and swath of light
rain, a dry slot will cross our area around mid/late morning
Thursday. During the afternoon and evening, the core of the 500
MB low will then sink into northern Iowa and push through a
stronger surface cold front. Currently, the expectation is that
this front will enter our northwestern counties around
Estherville and Emmetsburg a little before noon Thursday, and
reach our southeastern counties around Oskaloosa and Ottumwa by
the late afternoon. Strong low-level cold air advection will
surge in behind this front, with forecast soundings showing the
rapid development of steep low-level lapse rates and meager
instability, along with turbulent mixing and resultant gusty
winds. Although deep-layer forcing for ascent is weaker by this
time, the low-level frontogenetical forcing and weak instability
will support the development of snow showers. A relatively deep
saturated layer within the dendritic zone indicates the
potential for brief periods of intensely falling snow, even if
the resulting accumulation is very light. Nearly all model
output indicates light QPF/radar returns, and several including
the NAM are depicting 25-50 J/KG of surface-based CAPE during
this time. Combined with the expectation of strong and gusty
winds, concerns are gradually increasing for travel impacts
around Thursday afternoon/evening due to a combination of
reduced visibility in falling/blowing snow, strengthening
crosswinds, and potentially a flash freeze on some roads as
temperatures fall rapidly. It remains to be seen whether the
ingredients will come together sufficiently for such hazards to
manifest themselves, but the potential is certainly there.

Thursday night into Friday morning will be cooler once again
behind the front, however this will be short-lived. By Friday
afternoon weak ridging will move overhead and surface winds will
come around to south southwest again. Thereafter, a relatively
dry and quiet synoptic pattern will set in with very low
precipitation chances and alternating days of mild to near
normal temperatures.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1122 AM CST Tue Dec 16 2025

VFR conditions will prevail today, with only some high clouds
around FL200-250. Fog may develop again late tonight into early
Wednesday, roughly around 10-15Z, however confidence in more
than light BR is low and have only advertised 6SM BR in the
TAFs accordingly. Also, there is likely to be a brief period of
LLWS 30-40 KT this evening after sunset, mainly at the northern
terminals (FOD/MCW/ALO).

&&

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

&&

$$

DISCUSSION...Lee
AVIATION...Lee