913
FXUS63 KDMX 162328
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
628 PM CDT Thu Jul 16 2026

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

.KEY MESSAGES...

- Hot and humid conditions continue both today and tomorrow with
  a low (20%) chance for isolated showers and thunderstorms
  until sunset.

- The heat looks to linger through the weekend before a pattern
  change takes place, leading to relatively cooler temperatures
  and increased precipitation chances.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 208 PM CDT Thu Jul 16 2026

Currently, scattered cumulus have formed across Iowa. GOES imagery
has the highest coverage across the western part of the state. This
afternoon, there is a low (20%) for showers and potentially an
isolated non-severe thunderstorm. This is caused mainly by the high
that has been over us for the past several days moving just outside
of our area, allowing for subtle forcing to arrive.

Today`s forecast is very similar to yesterday`s. High temperatures
will be in the upper 80s to low 90s with dewpoints around 70. Like
yesterday, temperatures have been poked down a degree or two. In a
similar fashion, dewpoints were poked up a degree or two. This leads
to heat index values in the upper 90s across the state. This
afternoon, there are low chances for popcorn thunderstorms. Today`s
lapse rates are decent with ample CAPE, although the lack of any
shear will dampen the severe threat and will lead to storms being
either slow-moving or stationary. Some deterministic model soundings
hint at the potential for gusty winds as thunderstorms collapse,
however nothing is progged at more than 30 mph. Furthermore, limited
forcing will lead to low chances for storm development in the first
place.

Thunderstorm chances decrease after sunset as instability wanes.
Unlike previous nights, cloud cover is expected across the south.
Naturally, this will lower the potential for fog tonight. Tomorrow,
dewpoints are forecast to be a degree or two higher, with temps
reaching into the low 90s across most of the state. Heat indices
around the 100 degree mark are expected. The most notable feature
for tomorrow`s forecast is the potential for showers and
thunderstorms. A weak moisture plume is shoved into southern and
southeastern Iowa which will aid in thunderstorm development.
Forcing will still be limited, but a small area of potential
vorticity will advect into Iowa from Missouri and provide some
amount of forcing. CAPE and moisture will once again be plentiful.
Despite all of this, thunderstorm development is still expected to
be very isolated and "popcorn-y" with very little shear to steer
thunderstorms.

Tomorrow night, temperatures look to be even warmer (in the mid 70s)
which could have implications on overnight recovery from heat, even
if we remain below criteria for any headlines. Cloud cover is
forecast to be less than tonight, which could lead to the potential
for fog to return if dewpoints over-perform in the nighttime
hours.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 208 PM CDT Thu Jul 16 2026

The high continues to be pinched off as an upper level ridge builds
over the western CONUS this weekend and early next week. Uncertainty
lies in how quickly this happens. LREF clusters hint that we could
be out from under the ridge as soon as Sunday night/Monday, although
it is most likely that we stay under it or on the edge through the
day Monday. A surge of warmer air enters the area this weekend just
before the ridge translates away from us, leading to the potential
for the highest temperatures of this stretch to end the weekend. The
Extreme Forecast Index (EFI) is keying in on this, highlighting part
of Iowa as having above normal temperatures. With this still being
several days out, it is a trend to monitor. Of note, long-term
deterministic models key in on this as well. In tandem,
uncomfortably warm low temperatures are being forecast for the same
time period.

Once we are out of the ridge`s area of influence, we get into a
northwesterly flow regime which leads to a change of pattern and
increased potential for shower and thunderstorm chances across the
region at times next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 625 PM CDT Thu Jul 16 2026

Scattered showers have slowly been forming in western and
southern Iowa, with an outflow boundary near KDSM. Have added a
Prob30 group for showers there, as confidence is low on where
showers will form and how long they`ll last. Low confidence in
restrictions and lightning.

A SCT to BKN cloud deck will rise from Missouri overnight, seen
mostly at southern terminals. VFR conditions continue to prevail
tomorrow with a FEW to SCT cumulus deck.

&&

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

&&

$$

SHORT TERM...67
LONG TERM...67
AVIATION...Jimenez