899
FXUS63 KDMX 162322
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
622 PM CDT Thu Oct 16 2025

 ...Updated for the 00z Aviation Discussion...

.KEY MESSAGES...

- Warm and breezy to end the week, with highs today and Friday
  in the mid-70s to lower 80s.

- An approaching cool front will bring more showers and
  thunderstorms at times Friday through Saturday. The overall
  severe weather threat is low, but a few storms could be strong
  mainly across the southeastern half of Iowa late Friday.

- Dry and breezy conditions on Sunday may promote elevated fire
  weather concerns.

- Additional shower chances (<30%) return late Monday into
  Tuesday

&&

.DISCUSSION...
Issued at 244 PM CDT Thu Oct 16 2025

On and off rain showers and weak storms riding the large-scale ridge
continued across parts of central to eastern Iowa this morning,
though the increasing warm air advection into the state through the
day has elongated the ridge vertically to the north, pushing these
showers out of the state with dry conditions across Iowa this
afternoon. The increase in low-level southerly flow in the area,
along with a tightened pressure gradient overhead has brought breezy
winds, especially northern/western Iowa where gusts up to 25+ knots
have occasionally been reported so far today and will continue into
the early evening before decreasing slightly. This increase in warm
air advection has been warming temperatures over the region as well,
though there is a sharp difference in values as afternoon values
range in the mid to upper 70s across the southwest half of the
state, while the northeast is cooler in the upper 50s to 60s. This
is largely attributed to the clearing skies southwest allowing for
better warming, while further north and east still have lingering
low to mid-level cloud cover. These clouds will continue to lift
completely out of Iowa, and besides some occasional high clouds,
should see warming continue with highs expected to reach into the
mid 70s to low 80s, warmest southwest.

Looking further west, lee cyclogenesis has formed a large area of
low pressure centered over eastern Colorado into western
Nebraska/Kansas in relation to a large trough that has been
circulating over the western CONUS over the past few days now. This
low pressure system is expected to track northeast into the Upper
Midwest region this evening, particularly over the Dakotas into
Minnesota, keeping Iowa well within the warm sector and remaining
dry tonight into early Friday morning. Lows tonight are expected to
fall into the upper 50s to low 60s. A rather weak northeast to
southwest oriented frontal boundary from the aforementioned system,
along with a push of moisture into western Iowa will bring the next
chance for showers after sunrise Friday, tracking slowly eastward
through the day before stalling near east-central to eastern Iowa by
the evening. Following the weak frontal passage over most of the
state, temperatures will only be a touch cooler in the mid to upper
70s, while ahead of the front, values reach into the low 80s.
Guidance continues to indicate a better push of moisture into
east/southeast Iowa where the warmer air will be located by the
early evening, along with a gradually strengthening low level jet
that will result in a higher potential for showers and even storms
to develop. Instability present over the area, along with favorable
shear around or above 30+ knots will allow for at least a low chance
for a few strong storms. Looking further among models indicates a
variation in instability over south/east Iowa with the NAM/GFS
showing values under 500 J/kg, while the HRRR/RAP indicate higher
values around 500-1000 J/kg by Friday evening, which seems more
reasonable given the warm and moist environment ahead of the
boundary. The primary hazards with any strong storms, with even a
low severe risk, would be small hail and gusty winds. The SPC has
the area in a General Thunder outlook, though a Marginal Risk has
been introduced over a portion of far southern Iowa in the afternoon
update given the potential that currently exists. Something to
certainly monitor over the next several hours.

Showers and weaker storms look to linger over eastern/southern Iowa
into Saturday morning. Following a brief dry period through Saturday
afternoon for much of Iowa, a rather potent lobe of shortwave energy
within the larger circulation into southern Canada looks to pivot
down into Iowa Saturday evening, with another push of moisture into
eastern Iowa towards the Ohio Valley region and forcing for lift
which will result in the chance for redevelopment of showers and
storms over the same areas. Latest trends among guidance though seem
to keep much of this activity further south and east, with most if
not all activity near the boundary out of the state where the better
parameter space looks more likely to setup. However, weaker lift
into Central Iowa with lingering moisture along an ahead of an 850mb
cold front could bring a quick shot of light showers Saturday
evening. Lingering weaker showers may continue into early Sunday as
well, then conditions dry out across the region as dry air spreads
overhead with a large area of surface high pressure dropping
southeast across the western part of the Central Plains. This will
come with a rather strong push of northwesterly flow into Iowa that
will bring much cooler temperatures into the area, with highs
expected in the 60s. Breezy conditions with lower RH values in
the upper 20s to low 30s could lead to a potential for elevated
fire weather conditions as well. The dry conditions per longer
range guidance looks to hold into the start of the work week,
with a switch back o southwesterly flow ahead of another surface
low tracking eastward across the Upper Midwest, extending a
boundary into Iowa by Monday evening before departing Tuesday.
Per GFS, weak moisture and lift over the state keeps chances
mainly over north/northeast Iowa, though the Euro indicates more
extensive coverage across much of Iowa. Differences like this
are expected given this is several days out so will have to
watch, but not anticipating much impact in terms of significant
rainfall or storms at this time.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 622 PM CDT Thu Oct 16 2025

VFR through most of the period. MVFR expected as a line of
showers with a chance for some isolated thunder moves through
tomorrow. With uncertainty on the exact time this line could
move through have opted to use PROB30 groups for the
precipitation window. Winds will generally start to lose their
gusts this evening as temperatures fall and mixing comes to an
end. Similarly tomorrow as temperatures rise the gusts will
return. Winds aloft will remain gusty as the surface winds fall
creating a period of LLWS this evening into tonight.

&&

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

&&

$$

DISCUSSION...Bury
AVIATION...NC