366
FXUS63 KDMX 070812
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
312 AM CDT Tue Oct 7 2025

.KEY MESSAGES...

- Scattered showers with isolated lightning ending around to just
  after sunrise today, then drying with slightly warmer
  temperatures.

- Dry with seasonal temperatures Tuesday through Thursday.

- Breezy Thursday, then a low chance (20-25%) for isolated showers
  Friday

&&

.UPDATE...
Issued at 309 AM CDT Tue Oct 7 2025

Scattered rain showers with some occasional lightning remains over
southern Iowa, with more isolated shower activity into central Iowa
that continues to track east/northeastward early this morning, which
is tied to weak forcing and moisture return that remains overhead
post surface frontal passage, with the large trough and surface low
in relation to this feature over southern Canada. These showers are
expected to remain at least until sunrise or just after, with some
isolated lightning still possible but nothing more then that
expected given little to no instability overhead. Additional
rainfall totals in the areas that get this isolated to scattered
shower activity are expected to be below a half inch at most, with
highest values over southern Iowa. Dry weather then returns for the
rest of today as dry air overtakes the state as upper level ridging
begins to shift into the Plains and surface high pressure settles
over the Midwest. Cloud cover will largely decrease through the day,
outside of some cumulus developing into northern Iowa by the
afternoon, with mostly sunny skies otherwise expected. Despite
northerly flow over the state, mostly clear skies will lead to
warmer temperatures than many areas experienced yesterday, as highs
are expected to top out in the 60s. Tonight into Wednesday,
temperatures will plummet across the state, with lows expected in
the upper 30s northeast to mid 40s southwest. Given expected
efficient radiational cooling with mainly clear skies and light
winds, temperatures could be a bit cooler than forecast, which could
lead to a low potential for frost so will keep an eye on that.

The influence of surface high pressure will keep conditions dry and
quiet through midweek, with temperatures gradually warming into the
70s into Thursday/Friday as the low level flow pattern returns
southerly. Winds turn breezy Thursday as well, with low chances (20-
25%) for rain returning into Friday as weak frontal boundary
from a passing shortwave moves through. Models are not in good
agreement on coverage and timing, so more details will be better
known in the coming days, though concerns are low for any
notable impacts at this time.

&&

.DISCUSSION...
Issued at 212 PM CDT Mon Oct 6 2025

A cold front has been very slow to move across the state the past 24
hrs as the boundary has become nearly parallel to upper
west/southwest flow. The surface boundary has no reached far
southeast Iowa. The boundary at 850 mb though is lagging and remains
on the northwest half of Iowa side to begin the afternoon. Numerous
waves of theta-e advection continue to lift in vicinity of that
boundary. As a result, periodic showers along with some isolated
thunderstorms have been moving across a large portion of central
Iowa. All of these features will begin to accelerate to the
southeast later today and tonight as a 500 mb short wave trough
approaches from the west/northwest and moves through overnight.

High pressure will arrive on Tuesday and bring clearing skies along
with warmer than today temperatures, but still near to slightly
below normal temperatures with high temperatures generally in the
60s. The high pressure ridge will move slowly east the next several
days with return flow arriving on the backside of the system,
especially towards the end of the week. Expect high temperatures to
be similar with highs in the 60s and low 70s through Thursday.
Overnight lows may dip into the upper 30s Tuesday through Thursday
mornings over parts of northern Iowa where better radiational
conditions develop. A short wave moves through Thursday night and
could bring a few showers or isolated thunderstorms. Another high
pressure system follows this system with even stronger warm
advection for next weekend and perhaps a few areas with have highs
in the 80s once again.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1054 PM CDT Mon Oct 6 2025

IFR conditions are common over southern Iowa including at OTM
where showers will continue off and on overnight. There remains
the chance for a thunderstorm and have continued PROB30 at this
site after 6z. At DSM after 6z, showers are rather spotty with
confidence too low to include more than PROB30. Elsewhere, VFR
conditions prevail and will expand to all sites by around
daybreak Tuesday. Winds from a northerly direction will prevail
under 12 knots with occasional gusts to around 15 knots possible
during the afternoon. VFR cumulus clouds move over northern
Iowa in the afternoon and have continued mention at MCW.

&&

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

&&

$$

UPDATE...Bury
DISCUSSION...Donavon
AVIATION...Ansorge