Agency Iowa Weather Forecast Discussion

050
FXUS63 KDMX 110712
AFDDMX
Area Forecast Discussion
National Weather Service Des Moines IA
212 AM CDT Sat Oct 11 2025
.KEY MESSAGES...
- Warming trend this weekend, maxing out on Sunday with highs
  near 80.
- 20-40% rain chances return Sunday (north/northwest) and Sunday
  night (more widespread).
- Seasonal temperatures expected for the first half of next
  week.
&&
.UPDATE...
Issued at 212 AM CDT Sat Oct 11 2025
Quiet weather today but with another storm system emerging over
the Rockies and moving into the High Plains tonight and Sunday.
Tight surface pressure gradient ahead of this system will result
in gusty south southeast breezes across our service area and
have increased forecast speeds a bit further from late today
through Sunday accordingly. While warm air advection aloft and
forcing for ascent will also increase as the trough approaches,
generating light QPF in some model solutions, forecast soundings
unanimously depict impressive low-level dry air profile and have
maintained a dry forecast tonight, with some low (20-30%) POPs
in our north/northwest on Sunday, and more widespread (30-40%)
POPs coming Sunday night as the trough moves through.
Instability appears minimal and severe weather is not expected.
&&
.DISCUSSION...
Issued at 221 PM CDT Fri Oct 10 2025
The most notable change with the frontal passage was the drop in
moisture, hence the sunny skies and low relative humidity values.
CAA has been weak and the pressure changes have only been on the
order of 1-3mb across the north. This is why this front didn`t have
the characteristic gustiness in its wake. Temperatures won`t slide
until high pressure makes its presence better known tomorrow. Until
we get there, highs will be in the mid to upper 70s today. The warm,
dry conditions give some concerns for fire weather in northern Iowa,
but the lack of winds will help mitigate the chance of any fires
spreading. A gust to 25mph can`t be ruled out near the IA-MN state
line during peak heating, owed mostly to mixing efficiency and
subsidence. This is also why the SPC has an elevated fire weather
zone highlighted in the fire weather outlook today.
A deep upper-level low sat over the coast of the Pacific Northwest
today and worked to build the ridge back over the lee of the Rockies
and into the western High Plains. The surface high directly ahead
will stall the WAA for Iowa on Saturday, bottoming out lows tonight
in the low 40s (and perhaps some upper 30s) in northern Iowa. Highs
tomorrow will hover near 70 degrees. Some midlevel cloudiness will
make its way into western and northwest Iowa late in the afternoon.
The aforementioned upper low will elongate into a longwave trough
over much of the western CONUS, transporting Pacific monsoonal
moisture across the Plains. What this translates to is midlevel
cloudiness for Sunday, especially as there is a lag in low-level
saturation, but precipitation doesn`t enter the conversation until
late Sunday night. A compartment of the longwave trough will deepen
and negatively tilt over the Northern Plains, pulling the moisture
axis into the Dakotas. Similar to last night, the better kinematic
setup will not be over Iowa. A low chance for thunderstorms remains
for Iowa (~20%). Chances for precipitation have trended down, but
could increase if lee side troughing develops again (similar to last
night) in response to the broad synoptic forcing, aiding in moisture
transport into southern Iowa. Right now, the favored solution is an
H850 cyclone dropping into the Southern Plains.
This fropa will be more dynamic compared to the fropa this morning
with a more pronounced pressure gradient and CAA. So it will be
breezy ahead on Sunday and then cooler behind the front on Monday,
pushing closer to average for the beginning of next week (mid to
upper 60s). Troughing continues to hold over much of the western
CONUS, keeping rain chances in play for much of next week, perhaps
apexing with a more dynamic setup in the region at the end of the
period.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1030 PM CDT Fri Oct 10 2025
VFR conditions prevail through the period. Scattered mid-level
cloud cover has started to slowly move in over the western
portions of the state tonight. This will generally drift
eastward into Saturday, with greatest coverage over western
Iowa. Light northerly winds will become more easterly by
morning, and continue to veer to a more southeasterly direction
by Saturday afternoon. Light winds will increase to around 10 to
12 kts tomorrow afternoon. By Saturday evening, breezier
conditions with gusts around 15 to 20 kts will develop in the
west, impacting KFOD toward the end of this TAF period.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
UPDATE...Lee
DISCUSSION...Jimenez
AVIATION...Dodson

NWS DMX Office Area Forecast Discussion