308
FXUS63 KDMX 091740
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1240 PM CDT Thu Oct 9 2025

 ...Updated for the 18z Aviation Discussion...

.KEY MESSAGES...

- Increasing winds today, with highest gusts over northwestern
  Iowa. Isolated elevated fire weather conditions are possible
  as well over northwestern Iowa.

- A slight chance (20-30%) for rain showers mainly into eastern
  and southern Iowa late tonight into Friday. A few weak storms
  are also possible, though a strong storm cannot be ruled out.

- Dry conditions return by Friday afternoon, remaining dry
  until Sunday. Highs in the 60s to 70s are expected.

&&

.UPDATE...
Issued at 353 AM CDT Thu Oct 9 2025

Surface high pressure centered over the Great Lakes early this
morning is keeping conditions quiet and dry over Iowa. Temperatures
are cool across the state, but a bit warmer than they were at this
time yesterday as winds shifted southeasterly and are light,
with temperatures in the 40s to low 50s. This feature will
continue to move east out of Iowa through today, with
southwesterly low level flow increasing into Iowa that will
bring warmer air into the region, with highs anticipated to
reach into the 70s. This increasing flow and a tightening
pressure gradient developing into northern/western Iowa this
morning into the afternoon will bring breezy winds into the
state. Winds are expected around 20-30 mph, highest northwest
where a few isolated 35 mph gusts are also possible. In terms of
elevated fire weather concerns in cropland, the potential
remains fairly isolated over parts of the northwest this
afternoon due to the aforementioned breezy winds, along with RH
values in the upper 30s to low 40s. Therefore, marginal
conditions should keep the overall risk for fire starts to be
slightly less than originally expected. Regardless, it will
still be important to maintain farm equipment to avoid sparking
that could lead to fire starts and spread in these conditions.

A deepening shortwave trough over southern Iowa gradually dropping
out of Canada is still expected to track into the Great Lakes this
evening into Friday morning. A boundary in relation to this system,
with increased forcing and moisture return into Iowa will allow for
returning chances for showers late tonight through much of Friday
morning. Given dry air remaining initially overhead, any rainfall
will struggle to reach the surface, as the main moisture axis
generally remains into WI extending into northeast Iowa. Models
indicate that better saturation will gradually occur through the
column mainly over southern and eastern Iowa through the morning
though some minor variations are present on thinking of the degree
of saturation and area of coverage. Therefore, have kept more of a
broad coverage of PoPs in the forecast to address the remaining
uncertainty, with at least minor changes expected to occur
today and tonight as details become better known. There also
remains the potential to see some elevated storms, with a
slightly increased chance as instability looks to be higher
around 1000 J/kg of MUCAPE, though shear remains less favorable
and weaker forcing overhead. Weak storms therefore remain
possible, though a strong storm or two cannot be ruled out, with
small hail the main threat as lapse rates try to steepen. The
general thunder outlook per SPC is reasonable. Any remaining
showers and weak storms are expected to move out by mid-late
morning Friday as dry air behind the boundary overtakes the
region with an upper-level ridge and associated surface high
pressure system descending into the Dakotas/Minnesota through
the day, with dry weather expected to remain through Saturday.

&&

.DISCUSSION...
Issued at 252 PM CDT Wed Oct 8 2025

Rest of Today and Tonight... High pressure over the Great Lakes
continues to be the main driver of the weather over the Upper
Mississippi Valley. This has given us continued clear skies
(outside of the diurnal cumulus) and light winds. This is also
why we have seen efficient raditional cooling overnight. The
best area of this cooling will shift where it was over northern
Iowa this past morning to northeast Iowa tonight into tomorrow
morning. While frost cannot be ruled out, it looks most likely
much farther east closer to the Mississippi River.

Thursday... On Thursday the Great Lakes high will continue to
move out to the east. With this motion another system will begin
to move in from the west. This will allow for increasing winds
from the tightening pressure gradient. Any frontal or
shortwaves aloft have their timing later in the day into
tomorrow night with respect to rain chances. So the daytime
should be dry and windy. Nothing near a critical fire weather
level, but high enough for some concern. This is especially true
for agriculture, as the GFDI Agriculture values are elevated
during the day tomorrow. As we head into the evening and
overnight a shortwave should provide enough broad lift to
support the chance for showers and maybe some isolated
thunderstorms. The main question here is if the depth of the
saturation will be enough for showers or storms. If the
saturation depth is enough, there is enough elevated
instability for a few elevated thunderstorms overnight. High
resolution guidance suggests a better setup to our north with a
more isolated chance across Iowa.

Friday into Next Week... Higher pressure to move in Friday into
Saturday providing more a mild and dry start to the weekend. By
Sunday another frontal passage (late day to overnight) provides
the next chance for rain. Looking into the NBM percentiles there
remains a spread. 50th percentile and lower keeps us dry with
75th and above providing widespread rain chances. Hopefully as
start to get into the high resolution window this can be
resolved better. Right now low NBM PoPs appear to be the best
approach. This pattern repeats multiple times over the next week
due to spread within global ensembles.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1240 PM CDT Thu Oct 9 2025

VFR this afternoon and evening with clear skies or FEW to SCT
VFR ceilings. Winds will be the main impact today with gusty
southerly winds up to around 20 knots. Wind gusts will fall off
around 00Z. There is a chance for some isolated showers or
thunderstorms late this evening into tonight. Added in some
PROB30 groups for this chance. Overall setup looks better to the
north, but likely enough to go with the PROB for now. As we
approach the 00Z TAFs hopefully confidence will be high enough
for a change in the PROB groups. Even if the rain does not
happen the ceilings will be low VFR/high MVFR. Kept them with
SHRA for now as well since the thunderstorm threat seems very
isolated at the moment. Looking ahead to tomorrow winds will
shift to the west in the morning and north in the afternoon
(generally after this TAF period).

&&

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

&&

$$

UPDATE...Bury
DISCUSSION...NC
AVIATION...NC