495
FXUS63 KDMX 031120
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
520 AM CST Tue Nov 3 2026

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

.KEY MESSAGES...

- More showers and thunderstorms are expected through the day
  today. There is a low chance of a few brief tornadoes, mainly
  across portions of southern Iowa through this afternoon.

- Light rain chances will linger from tonight through Thursday.
  Notably cooler weather is also forecast from Wednesday through
  Friday, with daily highs generally in the upper 40s to mid
  50s on those days.

- Drier weather returns from Friday through early next week,
  along with a slow warming trend over the weekend.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 131 AM CST Tue Nov 3 2026

A broad and deep trough will slowly cross the region today.
Currently, the 500 MB trough axis extends from the Red River of
the North down across Nebraska and into western Kansas where a
closed 500 MB low is centered. At the surface, there are two
low pressure centers anchoring the ends of the trough - one near
the arrowhead of northern Minnesota and the other on the
Oklahoma/Kansas border. The surface front extending between
these lows has entered far northwestern Iowa early this morning,
and will reach central Iowa by early this afternoon. Meanwhile,
the southern low will swing northeastward during the day and
across our service area tonight.

Currently, within the broad area of lift along the leading flank
of the southern low, a broad swath of showers and thunderstorms
is moving north northeastward across much of eastern Nebraska,
southern and central Iowa, western Missouri, and Kansas.
Earlier, on Monday evening, there were sporadic severe weather
reports from a few of these storms in eastern Kansas, however
they have since diminished in overall intensity. As the storms
percolate across our area early this morning the severe weather
risk will be low overall, however, as we have discussed for the
previous couple days there is a very low chance of a brief
tornado or two, mainly in southern Iowa. Low-level shear
profiles/hodographs are very favorable in that region, however,
the thermodynamic environment is marginal in the form of weak
lapse rates, a mostly saturated profile, and a weak near-surface
inversion.

The bulk of the early morning convection will clear our forecast
area by around or just after sunrise, followed by a relative
lull in the mid/late morning during which more widely scattered,
that is to say less numerous/widespread, showers and storms may
occur. During this time, the nearly stacked cyclone approaching
from the south will move over northern Missouri and toward
southern Iowa, preceded by some limited breaks in the clouds and
resulting in rapid low-level destabilization. By 18Z a pool of
strong 0-3 KM AGL CAPE in the 250-350 J/KG range will develop
across this region, with a ribbon of enhanced surface vorticity
and stretching potential extending up along and just ahead of
the surface front into southern/eastern portions of our forecast
area. It is expected that an arching cluster of storms will
move through carrying an attendant threat for isolated tornadoes
given the strength of both the low-level thermodynamic
environment and the continued strong near-surface shear profiles
ahead of the low and near the boundary. There are some
mitigating factors however, which is why SPC is advertising
"only" a Marginal Risk for severe weather in our southeast. For
one thing, while the near-surface instability is quite strong,
overall instability is relatively limited with SBCAPE of around
1000 J/KG and a deeply saturated profile. Low-level lapse rates
are progged to be better than on Monday, but still modest around
6.5-7.0 C/KM. Also, low-level speed shear remains impressive
but direction shear is not as impressive as during the preceding
periods, with a distinctly less curved and more straight
hodograph. Even so, any local backing of near- surface winds
ahead of the approaching low could enhance the tornado potential
and this threat is something we will be closely monitoring
through this afternoon.

By late in the day today and toward this evening, the low will
sit right over our area resulting in a continuation of rain
showers but with less instability/thunderstorm potential. Winds
will gradually turn around to northwesterly by late tonight and
begin to increase as the low begins to move up into Wisconsin by
sunrise Wednesday.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 131 AM CST Tue Nov 3 2026

On Wednesday and Wednesday night the stacked cyclone will
continue to move away from our area, across Wisconsin and up to
around Lake Superior. A large cloud/light rain shield wrapping
around its backside will pivot across Iowa during this time,
especially the northern half or so of the state, and generally
make for gray and blustery conditions with areas of light
rainfall. These conditions will persist from Wednesday right
through Thursday, with high temperatures on both days ranging
only in the upper 40s north to mid/upper 50s southeast; notably
cooler than we have seen in the last couple of weeks or so.

From Friday onward the forecast is much more quiet and dry as we
enter a period of west northwesterly 500 MB steering flow with
periods of modest ridging therein. No rain is forecast during
this time, and while Friday highs will remain cool in the upper
40s/50s once again, a slow warming trend will then bring them up
into the upper 50s/lower 60s by next Monday. This will make for
a very pleasant, if slightly cool, late autumn weekend across
the region.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 520 AM CST Tue Nov 3 2026

Low IFR ceilings will prevail for much of the TAF period, except
for a period of relative clearing this afternoon into evening
mainly at DSM/OTM where MVFR or briefly VFR conditions may
return. In addition, periods of SHRA/TSRA remain likely mainly
early this morning and again around late afternoon. Have
attempted to time these periods in the 12Z TAFs, but amendments
are likely through the day.

&&

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

&&

$$

SHORT TERM...Lee
LONG TERM...Lee
AVIATION...Lee