847
FXUS63 KDMX 021734
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1134 AM CST Mon Nov 2 2026

 ...Updated for the 18z Aviation Discussion...

.KEY MESSAGES...

- There is a Marginal Risk for severe weather for late Monday
  into Monday night, including after dark. Damaging winds and a
  tornado or two may be possible.

- Rain and storms remain possible Tuesday. Rain chances extend
  into Thursday for at least northern Iowa.

- Highs cool midweek with highs in the 40s possible for northern
  Iowa.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 142 AM CST Mon Nov 2 2026

A deep 500 MB trough is moving eastward over the Rockies early
this morning, preceded by several shortwave impulses that are
ejecting out into the central U.S. The first such shortwave is
moving over Iowa at this time and generating a broad swath of
light showers moving from west to east across our service area.
Another shortwave will move overhead this afternoon, then the
core of the trough will approach western Iowa late tonight.
Meanwhile, at the surface southeasterly flow covers the region
and the near-surface layer is saturated with widespread low
ceilings blanketing most of Iowa. This is keeping overnight
temperatures quite warm for the season as they are held up by
dewpoints in the mid to upper 50s areawide.

Regional radar imagery indicates that behind the leading swath
of light showers, which is moving across western and central
Iowa at this writing, scattered showers have developed across
much of Nebraska and Kansas, mitigating expectations of a lull
in precipitation later today. It seems more likely that behind
the first push of light rain, we will continue to see occasional
showers for much of the day. That being said, as the synoptic
surface front approaches the Missouri River valley late this
afternoon and evening, a narrow dry slot preceding it may work
into our western counties and allow for some modest
destabilization. The parameter space for most of today is not
favorable for severe weather with ample shear but very limited
instability. As we progress toward the end of the day and into
tonight, however, a surface cyclone will deepen over
central/eastern Kansas as the main 500 MB trough axis moves over
the High Plains. Instability will increase ahead of this surface
low within a region of increasingly favorable low-level shear
profiles and thunderstorms developing in eastern Kansas will
rocket northeastward across Iowa mainly after dark tonight.
Forecast soundings indicate strong low-level and deep-layer
shear and increasing low-level instability with 0-3 KM AGL CAPE
reaching 175-200 J/KG in our southwestern counties roughly
between 02Z and 08Z or so. There are also signs of modest mid-
level drying during that time, and these environmental
conditions would seem to favor a threat of both severe
straight-line winds and tornadoes. However, the big fly in the
ointment is the degree to which the near-surface environment
will or will not be realized. The same forecast soundings
persistently depict a shallow saturated and stable layer will
persist, with modest surface lapse rates around 5.5 C/KM. The
most likely scenario is one in which showers and thunderstorms
move across our forecast area tonight, but remain elevated and
thus far less capable of producing severe weather. SPC outlooks
depict this well with only a Marginal Risk over the southwestern
half or so of Iowa, however, we will be closely monitoring today
and tonight in case it appears the environment may become more
favorable for surface-based convection, in which case the
tornado and wind threats would increase accordingly.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 141 PM CST Sun Nov 1 2026

The stalled upper low will sink towards Iowa on Tuesday and its dry
slot will rode the midlevel clouds and allow for some of the stratus
to mix out. The cold front will exit the area in the early morning
and add to the mixing potential with CAA. Post-frontal storms will
be possible as low-level lapse rates steepen and will contribute to
the gusty winds that afternoon. Storms could trend stronger if the
dry slot comes more north into the state, allowing for lapse rates
in the midlevels to steepen out once more. Wednesday and
Thursday have trended colder. This is because the upper low will
park right over Iowa Wednesday and all but guarantee stratus
and rain until the TROWAL departs late Thursday. Highs may very
well trend down and into the 40s. Highs will recover back into
the 50s and 60s once the flow resumes a southerly component.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1133 AM CST Mon Nov 2 2026

IFR to MVFR conditions are expected at all sites this TAF period.
Thick, low clouds are over most of the region at the moment
impacting all TAF sites with ceiling restrictions. KOTM is expected
to have a few hours of MVFR ceilings. Winds will be breezy from the
south at 10-15kts gusting as high as 35kts across much of the state
through the period, with lowered gusts during the overnight hours.
Toward the end of the period, winds will begin to shift to becoming
from the northwest as a cold front moves across the state. Showers
are also ongoing across much of the state and are expected to
continue through the entire TAF period. Thunderstorms may occur at
times at all sites, which have been handled as PROB30 groups for the
most likely time window. Ceiling and visibility trends are difficult
to capture in advance with any specific shower and/or thunderstorm,
so adjustments via amendments will be made from METAR and radar
observations through the period.

&&

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

&&

$$

SHORT TERM...Lee
LONG TERM...Jimenez
AVIATION...67