753
FXUS63 KDMX 112345
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
645 PM CDT Fri Jul 11 2025

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

.KEY MESSAGES...

- Today, thunderstorms this afternoon will be capable of
  producing heavy rain, damaging wind, and a few tornadoes,
  especially areas east of I-35. Please remain weather aware,
  and never drive through flood waters.

- This weekend, drying out with additional rain chances Tuesday
  and Wendesday.

- Late next week, cooler temperatures arrive for Thursday and
  Friday.

&&

.DISCUSSION...
Issued at 147 PM CDT Fri Jul 11 2025

TODAY...Thunderstorms capable of heavy rain, damaging wind, and
event a few tornadoes are expected this afternoon and evening.
Early afternoon satellite and radar imagery shows storms across
much of the region as of 2PM. For the rest of today, multiple
rounds of storms could lead to heavy rain and flooding. There is
also a severe weather threat with these storms, with damaging
wind and a few tornadoes being the primary threat.

A weak surface low was centered across southern Iowa, with
southeast winds ahead of it.Temperautres were in the mid 80s,
with dewpoints in the mid to upper 70s. This warm and unstable
airmass will be the main driver for thunderstorms today, while
upstream an upper level wave along the IA/NE border will
provide the forcing for ascent.

The main question will be how long storms will be discrete in
the warm sector, vs how quickly they will grow upscale into a
line. This is one of the key factors for whether or not
tornadoes or damaging wind will be the primary threat. Even if
storms do develop into a line, the low level shear could support
QLCS tornadoes, so have a Tornado Watch in effect for mainly the
Southeast part of Iowa, including the Des Moines metro. North of
this, a severe thunderstorm watch is in effect, where confidence
is higher in a wind and/or hail threat.

In addition to the severe threat, heavy rain is also a concern
given the PWAT values near or above 2 inches. Training storms
along an ill-defined warm front could produce rainfall totals
of 2 to 3 inches, with a few pockets close to 4 inches based on
the local probability matched mean of the HREF.

SATURDAY THROUGH FRIDAY...Storms will move east tonight, and the
weather will dry out over the weekend and into early next week.
The next chance for storms will be Tuesday into Wednesday as a
cold front moves through the region. A few storms could be
strong to severe, but as of now there isn`t a signal that this
will be anything noteworthy. Looking ahead, if the cold front is
able to push through, temperatures will cool off toward the end
of week, with highs closer to 80s. If it hangs up across the
region, then expect continued chances for showers and
thunderstorms.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 640 PM CDT Fri Jul 11 2025

Remnant IFR/MVFR TSRA will continue to clear from west to east
especially for DSM and OTM sites over the next couple of hours.
Sites farther north and west have lingering MVFR/low VFR cigs which
are expected to remain in place throughout this evening. Another
round of SHRA/TSRA was hinted in latest CAMs approaching for FOD but
was not confident on coverage overnight as the environment only
continues to decay for convective support. IFR/LIFR fog is possible
late tonight for most sites but should mix out around 12-14z
tomorrow morning. Cigs and vsby improve to MVFR late morning and
then VFR by early afternoon. Light and variable winds will shift
northwest and becoming breezy with gusts near 20kts for the northern
sites.

&&

.HYDROLOGY...
Issued at 147 PM CDT Fri Jul 11 2025

As mentioned earlier in the main discussion, training
thunderstorms are the main concern this afternoon, before the
storms form into a line and move east this evening. The
atmospheric profile is very moist, with PWAT values near 2
inches. Mid level lapse rates of only 5 to 6 C/km, together with
high freezing levels will lead to heavy rainfall rates that
could cause flash flooding over any urban area.

As for the rivers, this rainfall will lead to rises on the
rivers, with a few locations seeing Minor flooding. There is a
non-zero chance for Moderate flooding, but the overall threat
for that category or higher is low. The areas most at risk for
flooding are the ones that had the rainfall last night, and the
smaller bases that see the heaviest rain would be the quickest
to respond. Fortunately this will be the last rainfall event for
at least a few days.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 1 AM CDT Saturday for IAZ038-039-049-050-
059>062-072>075-084>086-095>097.

&&

$$

DISCUSSION...MPX
AVIATION...MPX/Dunleavy
HYDROLOGY...MPX