462
FXUS63 KDMX 021124
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
624 AM CDT Sat Aug 2 2025

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

.KEY MESSAGES...

- Relatively dry and comfortable conditions this weekend. Smoky
  through Sunday morning.

- Rain chances (<15%) into far western Iowa Sunday morning,
  with intermittent low chances for rain west and northwest
  through the beginning of the work week.

- Warmer and increasing rain chances mid to late next week.

&&

.DISCUSSION...
Issued at 150 PM CDT Fri Aug 1 2025

Broad surface high pressure continues over the midwest today,
keeping a steady stream of cool, dry easterly surface flow over
Iowa. Farther aloft, the upper level pattern shows generally
northwesterly flow over Iowa as the state sits on the transition
from messy ridging in the western CONUS and large scale troughing
over the eastern/northeastern CONUS. There will be weak waves of
energy ejecting through this northwesterly flow, but with little
change in the upper level pattern, the surface high pressure will
generally remain in place through the weekend. This will hold the
main axis of moisture over the plains region to our west, and
keeping the area mostly dry through at least Saturday. Precipitation
will still be occurring to our west and drifting east toward Iowa
with these pockets of weak forcing, but will diminish quickly as
they reach the drier forecast overhead. However, can`t rule out some
lingering light showers/sprinkles as the activity dries out,
especially in far western Iowa. This will be especially true as we
get into Sunday morning when the surface high meets a slightly more
prominent wave and it`s associated low pressure, bringing the
moisture axis farther into western Iowa. Even then, the high
pressure holds on over the eastern half of Iowa, working against
precipitation chances looking to move farther east. Fortunately for
us in Iowa, the best instability axis will be co-located with the
moisture stream to our west, keeping anything other than a rogue
thunderstorm or two out of the forecast through Sunday.

Although conditions will be relatively quiet and comfortable this
weekend, we won`t be without some impacts over the area. Given our
more north northwesterly upper level flow, as well as our placement
just within the upper level trough digging down from our north,
Canadian wildfire smoke will continue overhead through at least
Saturday. Hazy skies will be the most visible impact with the
smoke, although slight visibility reductions will also be
experienced at times, especially overnight and in the morning
hours as smoke gets trapped within the inversion. Likewise, with
smoke at the surface there will also bring poor air quality in
the state. In coordination with the Iowa DNR Air Quality Bureau,
the statewide Air Quality Alert has been extended through
Sunday morning at 8 am. Through the day Sunday, should begin
seeing some improvement to smoke both at the surface and aloft
as the upper trough departs to the east and ridging continues to
build from the west.

Looking ahead to next week, the upper ridge will continue eastward,
bringing both warmer temperatures and slightly better moisture
aloft. This won`t occur all at once, as surface high pressure over
the great lakes will still work against building low pressure from
the west. What this will do is bring a trend towards more
shower/storm chances through the work week, beginning in the west
and northwest in the beginning of the week then building eastward
into the second half of the week. As this occurs, the main feature
to watch through the week will be the warmer temperatures moving in
, particularly aloft. Model soundings, 850 mb temps, and 700 mb
temperatures all show an elevated warm layer edging eastward through
the week. The edge of this warm layer will likely be the focal point
of diurnally driven storms through much of next week. That said,
it`s still too early to get too bogged down into the exact details.
With the building thermal ridge, we will also see temperatures warm
up through the week, steadily trending back to normal then likely
above normal by the end of the week.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 624 AM CDT Sat Aug 2 2025

Smoke persists across the area but is a bit thinner today,
resulting in mainly VFR visibilities with just some pockets of
MVFR at times. Have included TEMPO groups in the next couple
hours at MCW/OTM to account for this per observational trends,
but thereafter maintained prevailing VFR through the remainder
of the 12Z TAFs. If smoke thickens again then amendments may be
necessary today.

&&

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

&&

$$

DISCUSSION...Dodson
AVIATION...Lee