533
FXUS63 KDMX 121125
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
625 AM CDT Tue May 12 2026

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

.KEY MESSAGES...

- It will be breezy today, especially in northern Iowa this
  afternoon where northwest winds of near 30 MPH with gusts to
  near 40 MPH are forecast. This could lead to erratic behavior
  of any fires that occur, and may also cause blowing dust in
  some areas.

- A few light showers are also expected today, mainly across the
  northern/northeastern half of Iowa this morning. Gusty winds
  may occur near any decaying showers this afternoon.

- Warmer temperatures are forecast this week, especially from
  Friday into the weekend. Rain and thunderstorm chances will
  also return from late Thursday into Friday, then again over
  the weekend.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 207 AM CDT Tue May 12 2026

Well-advertised changes are afoot in the weather pattern, as
low-level winds have come around to roughly south across Iowa
and become gusty at times. This is promoting warm temperatures
in spite of nearly clear skies, with readings holding in the
mid-50s to lower 60s at this hour and not likely to fall much,
if any, farther. Meanwhile, an energetic 500 MB shortwave trough
is moving from North Dakota into Minnesota, with an attendance
surface low developing. As this system moves across Minnesota
toward Lake Superior today, it will push a trailing surface
front down into Iowa, crossing our area from around mid-morning
northwest to late afternoon southeast. Broken clouds are already
evident in satellite imagery ahead of the surface front,
however, regional radar shows any precipitation echoes are
spotty at best. As the synoptic system matures we should see an
increase in shower coverage across southern Minnesota and into
Wisconsin this morning, but it remains to be seen how much of
this will penetrate into Iowa. Most model solutions do depict
light rain moving through the region along and ahead of the
front, however, the bulk of this remains near the fringes of our
area across northeastern and into eastern Iowa later today. This
is primarily due to the upper-level support translating through
that area, closer to the departing cyclone, with our service
area remaining beneath more nebulous forcing. Even so, diurnal
destabilization and the approaching boundary would seem to
support convective initiation, however, there are several other
detracting factors. Low-level destabilization will be inhibited
by increasing cloud cover, as well as a pronounced lack of
moisture. Forecast soundings continue to depict a very dry and
well-mixed layer from the surface up to about 700 MB, and even
above that the saturated layer is relatively shallow and
transient. Given these considerations, it is likely we will see
scattered radar returns in the form of light showers, but with
much of the area remaining dry as any rain evaporates or reaches
the surface as sprinkles. There is enough support this morning
to maintain 20-30% PoPs, mainly in our northeastern half, with
warm air advection ahead of the trough providing extra support
and the dry air less pronounced early in the day, however, is is
expected any such morning showers will essentially mix out by
the afternoon and the forecast reflects that expectation.

Aside from precipitation/PoP considerations, strong winds are
also anticipated today as the system moves through. Winds will
gradually turn to southwest this morning and maintain speeds of
10-20 MPH with gusts to 25-30 MPH, weakening as the front
approaches. Behind the boundary, winds will swing around to
northwest and increase further, especially across northern Iowa
this afternoon. Forecast soundings persist in illustrating a
remarkably well-mixed layer extending up to nearly 700 MB, with
consistent wind speeds of 30-35 KT all through that layer
supporting surface sustained speeds of 25 KT or a bit higher in
our northern counties. Gusts will likely not be far above the
sustained speeds, perhaps 35 KT or so, however the sustained
winds are very close to Wind Advisory criteria and it is
possible one may be warranted later today. In addition to the
strong winds, it will also remain very dry today with Relative
Humidity falling into the 20-25% range across much of the area
in the late afternoon. However, any resulting fire weather
impacts are mitigated by the greenness of surface fuels this
late in the season. Finally, there is some potential for blowing
dust in parts of our area this afternoon, whether from the
strong environmental winds or near light showers/sprinkles,
given the inverted-V soundings. However, any such blowing dust
potential is not a high-confidence proposition at this time, and
it is not included in the official forecast, but will be
something to watch for as the day progresses.

A surface high pressure area will build down the High Plains on
Tuesday night, in wake of the system departing to the east. This
will result in clearing skies and gradually diminishing winds in
Iowa. The ridge axis will then move across Iowa Wednesday and
Wednesday night, providing for a very quiet, dry, and pleasant
day with Wednesday afternoon highs in the 70s and light winds
beneath sunny skies.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 251 PM CDT Mon May 11 2026

Milder air fills in behind the boundary Tuesday night into
Wednesday, but upper level ridging quickly builds eastward into
the state through mid-week. Temperatures will still reach the
70s under the surface high pressure on Wednesday, then into the
80s as southerly flow returns under the thermal ridge on
Thursday. The 500 mb ridging will be abbreviated, though, as
another 500 mb trough quickly begins to move in on the backside
of the ridge late Thursday into Friday. This will open the state
back up to a slug of gulf moisture, with broad warm, moist air
advecting into the state and bring the return of shower and
thunderstorm chances Thursday night into Friday. Instability
will be present on Friday afternoon, which could lead to some
stronger storms, although wind fields look less impressive at
this time range. Will better assess severe threat in the coming
days. The pattern looks to remain active and warm through the
weekend as well.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 625 AM CDT Tue May 12 2026

VFR conditions will prevail through the TAF period. A few
showers and thunderstorms will occur today, but
probability/duration of impact at any given terminal very low
(20%/30 minutes or less). Otherwise, primary aviation concern
is strong winds, from the SW initially today then turning to NW
by this afternoon and gradually abating after sunset tonight.

&&

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

&&

$$

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