720
FXUS63 KDMX 051146
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
646 AM CDT Sun Oct 5 2025

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

.KEY MESSAGES...

- Warm, dry, and windy conditions again today, making for
  elevated fire weather concerns for cropland but limited to the
  afternoon given expected rain and more marginal conditions.

- Spotty showers are possible from late this afternoon in
  northwest Iowa, moving across the area and becoming more
  widespread on Monday with a few storms possible. Rain chances
  remain through Tuesday morning with this frontal passage.

- Cooler highs in the 60s and 70s after today and remaining
  through the week.

&&

.UPDATE...
Issued at 358 AM CDT Sun Oct 5 2025

Dry and breezy conditions early this morning, with gusts around 20-
25 mph out of the south/southeast and temperatures through the 60s.
Southwesterly flow into Iowa continues to increase around 40-50
knots early this morning at 850mb, as the western Central Plains
continues to feel the influence of the large trough slowly pivoting
northeast, with a stronger area of surface low pressure centered
over South Dakota and a weaker low pressure area entering western
Kansas this morning. Further east, the western fringe of ridging
across the eastern CONUS still extends into Iowa, which will
gradually move away through today. The resultant tightened pressure
gradient across the northwest half of the state and stronger 850mb
winds remaining overhead today will result in another breezy day,
though decreasing slightly by the afternoon around 30-40 knots
in the low levels, with more limited mixing due to increasing
cloud cover through the morning as a boundary (more details on
this below) moves into the state. These factors should lead to
slightly lower gusts at the surface close to 25-35 mph per
soundings, highest over northwest Iowa. These winds, paired with
another day of above average temperatures in the low to mid 80s
and RH values falling into the mid 30s to low 40s will still
result in elevated fire weather concerns, again focused on
cropland but more limited given slightly lower winds and
slightly higher RH values. With the boundary expected to bring
showers mid-late afternoon, the overall window of fire danger is
smaller as well, roughly noon to 4pm, so an SPS was issued to
highlight this potential.

Radar returns over the region this morning depict a broad area of
rain showers over western Nebraska and across the Dakotas, where a
boundary is currently draped in relation to the low pressure areas
previously mentioned. The expectation is that this boundary will
continue to track eastward today as the trough and associated
surface lows continue to lift northeastward. This boundary is
expected per guidance to arrive into the state by the early evening
today, with showers trying to develop near and ahead of it by mid-
morning into the afternoon per CAMS, but will likely struggle to
make it to the surface given dry low levels. Better moisture return
into the late afternoon to evening, with better forcing as well will
lead to increased chances of showers oriented northeast to southwest
with the boundary over central Iowa. There remains the possibility
for some storms as well during this time, though instability is not
too notable, with values less than 500J /kg, though shear
values around 25-30 knots are suggested. Could see some gusty
winds with any storms given the drier air initially, followed by
increased forcing and moisture saturating the profile into the
evening through Monday morning, resulting in low severe
potential but rather appreciable rainfall, with PWATS
approaching 1.5 inches and warm cloud depths around 10-12 kft.
With the boundary across much of the state by Monday afternoon,
cooler temperatures will settle over most area with values in
the 60s, while southeast Iowa is expected to be much warmer yet
ahead of the front in the mid to upper 70s. Redevelopment of
showers is expected mainly over south/southeast Iowa Monday
evening, with a lower chance for some storms though should
remain non-severe. Lingering precipitation occurs into Tuesday
morning before drying across the state and remaining cooler in
the 60s. Rainfall totals from this evening through Tuesday
morning are expected to fall in the 0.75-1 inch range for many
areas, with minimal amounts over northwest Iowa and locally
higher amounts above an inch southwest.

&&

.DISCUSSION...
Issued at 228 PM CDT Sat Oct 4 2025

Warm, dry, and windy this afternoon around Iowa. By 2pm temperatures
had warmed into the mid to upper 80s while dewpoints were near 60 -
making for relative humidity in the 35-45% range so far. A quick
look at the surface maps shows a tight pressure gradient
setting up across Iowa with high pressure to the east and low
pressure to the west. This gradient, coupled with the dry air
and deep mixing in place, has resulted in gusts of 25-35+ mph so
far this afternoon with a few isolated gusts of 40+ mph. While
grasses remain fairly green, cropland is cured and susceptible
to fire weather concerns. Extreme care should be used with fires
or sparks today.

This evening the loss of diurnal heating will help to diminish
surface winds as an inversion sets up. By Sunday those breezy
conditions and warm temperatures will be back again, however. The
low will creep closer with a boundary reaching western Iowa on
Wednesday, bringing additional moisture and scattered cloud cover to
the area. This will battle the dry air in place and fire weather
concerns remain elevated ahead of the boundary passage on Sunday. A
spotty sprinkle or light shower is possible on Sunday, but dry air
will prevent anything more substantial.

By Monday deeper moisture arrives into the area as the western US
trough elongates and pushes east across the plain and midwest.
Sounding show continued moistening of the column by Sunday
night and Monday, allowing for more efficient rain production.
Model consensus is around 1-1.5 inches of rain with the line of
showers. With very little instability (<200 J/kg) and shear
lagging behind the boundary, the potential for stronger storms
is very low. Model struggle with evolution into Tuesday and
beyond. While the Euro favors a quicker exit as the front clears
the area by Tuesday morning, the GFS is slower with the
boundary and associated shower lingering through Tuesday night.
These timing differences also influence timing for a mid week
shortwave, something both models develop but with a difference
of ~36 hrs. Aside from precipitation uncertainty, temperatures
are expected to come down to more seasonal values with highs in
the 60s to 70s this week and lows in the 40s to 50s.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 646 AM CDT Sun Oct 5 2025

Breezy southwesterly winds are expected throughout much of the
day, with gusts up to 25-30 knots through the early evening
before turning light and shifting northwesterly across the state
into Monday. This wind shift will occur following a cold front
that will enter northwest Iowa later this afternoon and track
across Iowa through the evening and into Monday. Overall
confidence in rain showers increases after 21-00z for most
sites, though remaining dry at OTM until Monday morning. There
is a chance for thunderstorms with these showers into the
evening today, though the overall confidence on this occurring
remains low so have used PROB30 mentions at the majority of the
terminals and will adjust as needed.

&&

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

&&

$$

UPDATE...Bury
DISCUSSION...Hagenhoff
AVIATION...Bury