411
FXUS63 KDMX 272322
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
622 PM CDT Tue Oct 27 2026

 ...Updated for the 00z Aviation Discussion...

.KEY MESSAGES...

- Drying out for tonight and mild.

- Showers and thunderstorms become spotty to scattered ahead of
  a cold front later Wednesday afternoon and night. A few
  severe storms capable of large hail and gusty winds are
  possible from mid to late afternoon into early evening.

- Widespread rain chances move back into Iowa later Thursday
  night into Friday and Saturday leading to mild and perhaps
  damp conditions for trick-or-treating. Rumbles of thunder
  also possible on Friday.

- Temperatures remain seasonal if not above normal through the
  next week.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 246 PM CDT Tue Oct 27 2026

Showers have been dwindling in coverage this afternoon over central
into northeastern Iowa as lift weakens within the deeper saturation
as the southern stream shortwave pushes towards the western Great
Lakes. GOES-East Day Cloud Phase Distinction RGB shows these clouds
along with some mid and high level clouds over eastern portions of
Iowa into south central Iowa early this afternoon. Farther to the
northwest, low water clouds are fairly widespread and while breaks
are starting to show up in the cloud deck, RAP cross section
show high amounts of low level saturation persisting into
tonight. These clouds and where there have been showers have
once again kept temperatures below the initial National Blend of
Models guidance this afternoon. We currently do not look to
contend with fog tonight given increasing or thickening clouds
along with winds that stay around or above 5 mph.

Attention on Wednesday will be on the stronger shortwave trough in
the northern stream that will be moving through the south central
Canadian provinces and the northern US states. Attached to this
shortwave will be a southward trailing cold front that will reach
the state later in the afternoon and move through our forecast area
Wednesday night. Ahead of this front will be breezy southerly
winds sustained at 10 to 20 mph with gusts of 25 to 30 mph
common. While there could be a few spotty showers in the warm
air advection regime ahead of this front, expecting some degree
of sunshine that will boost temperatures well into the 70s.
These warm and windy conditions will push the cropland fire
danger index into the high category (level 3 out of a max of 5).
A mitigating factor to fire weather concerns will be that the
minimum relative humidity values will stay generally above 50%
as southerly winds draw near 60 degree dewpoint into portions of
the state.

Spotty to scattered thunderstorms are expected to develop ahead
of this cold front with CAPE values up to around 1000 J/kg
forecast with good low level kinematics typical of an autumn
severe weather set up. The strongest forcing will be closer to
the surface low well north of Iowa where QG convergence will be
maximized. Lapse rates remain on the weaker side generally below
7C/km and CAPE profiles are rather skinny. However, severe hail
greater than 1" in diameter up to perhaps golf ball sized will
be possible with a few storms along with gusty winds given the
dry mid-level air over northern into western Iowa. This is where
convective allowing models show storms developing with some of
the more robust models (NAMNest, FV3 cores) having a few to
several decent updraft helicity (UH) tracks. The SPC marginal
outlook area seems to cover most of these UH tracks, which
continues to be supported by the ML/AI/SI guidance. The
strongest storms and highest severe potential will wane by mid-
evening if not shortly after sunset as storms weaken, but storms
will still move across the rest of the area. The front and most
of the showers and waning intensity storms will be clear of our
forecast area by sunrise Thursday.

As the front sinks and stalls over northern Missouri on Thursday,
Iowa should experience a period of dry and warm conditions. This
will be short-lived as the next shortwave trough in the southern
stream begins to take shape over the southern Plains. Warm air
advection will begin to push into Iowa Thursday night ahead of
this shortwave, which will result in the return of shower and
thunderstorm chances from southern into central Iowa by sunrise
Friday.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 246 PM CDT Tue Oct 27 2026

While it will not rain continuously, showers are expected from
Friday through a good portion of Saturday across many portions of
Iowa with peals of thunder likely on Friday as well. There is
variability in the models whether this rain will last all the
way through Saturday or if Saturday starts to turn drier or if
Sunday morning will have lingering showers as well. Regardless,
trick or treaters will encounter mild conditions and perhaps
damp ones as well Friday or Saturday evening depending on when
the festivities are held. Quickly following this southern
stream wave will be a more pronounced mid-level trough or closed
low that will push over the Rockies by the start of next week
and into the central part of the country by the middle of next
week. While there is uncertainty in the exact mid-level pattern
evolution early next week, confidence is increasing in another
round of showers and thunderstorms in this timeframe. With this
being one of several rounds of rainfall spread out over the next
week with total rainfall between 1.5 and 2.5 inches over the
state from the grand ensemble, some within bank rises are
possible on mainly smaller streams and tributaries to the larger
rivers according to recent runs of the National Water Model
forced by the NBM and GFS.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 622 PM CDT Tue Oct 27 2026

Low clouds and occasionally reduced visibilities in patchy fog
are resulting in MVFR (with isolated IFR) conditions in
northwestern Iowa, including at FOD and MCW. Elsewhere VFR
conditions prevail. The ceilings should slowly lift and move
more northward tonight, bringing FOD and MCW up to VFR but with
the timing of this improvement still uncertain. For now have
maintained prevailing or TEMPO MVFR at those two sites until
about 05-08Z and will monitor short-term trends overnight. There
is also a low chance (<30%) of showers on Wednesday morning and
again right around the end of the 00Z TAF period, but neither is
advertised at this range due to the low probability.

&&

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

&&

$$

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