636
FXUS63 KDMX 122352
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
652 PM CDT Wed Aug 12 2026

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

.KEY MESSAGES...

- Early morning thunderstorms are forecast once again on
  Thursday morning, then scattered thunderstorm chances last
  through Thursday afternoon and evening. Strong wind, hail, and
  heavy rain are the main concerns with these storms.

- Additional thunderstorms are possible overnight and early
  Friday morning and will depend on how the Thursday storms
  evolve. These storms could be severe with pockets of heavy
  rain as well.

- The pattern remains active with storms chances through the
  weekend and early next week.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 142 PM CDT Wed Aug 12 2026

Morning thunderstorms across Iowa are pushing east with clearing
occurring quickly across western and central Iowa. Temperatures
have recovered into the mid 80s this afternoon, though morning
convection has helped to keep temperatures a few degrees cooler
today. A weak boundary across northern Missouri will see
convection bubble through this afternoon, however capping in
place should keep Iowa dry.

This evening a shortwave will ride across the thermal ridge from
South Dakota and Nebraska with the MCS expected to reach Iowa early
Thursday morning. As the MCS reaches Iowa it is expected to ride
along the instability gradient (2000+ J/kg MLCAPE) as the weak
Missouri boundary lifts north back into Iowa overnight. There
are two main areas of uncertainty with the Thursday morning MCS
in Iowa: location and strength. Current expectation for the MCS
is to travel across central Iowa with the main bowing segment
along roughly the I- 80 corridor, however this placement will
depend on how far north the instability axis lifts into the
state. Strength is also uncertain. This will be the third night
in a row with the potential for overnight or early morning
storms across Iowa. While the previous two nights have had less
upper level support, tonight`s complex is supported by an upper
level shortwave that makes a stronger MCS more likely. As it
reaches Iowa the continued intensity will be driven primarily by
how far north instability axis can lift to feed the complex.
Current data suggests the low level jet will reach northern
Missouri with the boundary being push just north of the jet into
Iowa. MLCAPE of 2000+ CAPE will be in place with mid level
lapse rates around 7 C/km. There is plenty of moisture in place
with PWATs of 1.5-2+". While the MCS should be fairly
progressive, ribbons of 2- 3+" are possible and could cause
ponding or minor flooding.

This morning convection will help to squash the thermal ridge,
shoving the heat south with highs in the upper 70s to low 80s in
northern to central Iowa on Thursday while southern Iowa still warms
to near 90. After a daytime lull, afternoon convection is
expected to develop along the lingering boundary with less
capping across the area. Further redevelopment is anticipated
overnight Thursday into Friday morning, though placement is less
certain and will depend on where outflow boundaries from
earlier round of convection and the low level jet set up. The
east-west orientation of convection Thursday afternoon and again
overnight will be less progressive and could result in hydro
concerns with training storms over the same locations. This will
need close monitoring with PWATs remaining around 2" along with
those deep warm cloud layers.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 142 PM CDT Wed Aug 12 2026

Overnight convection lingers into Friday morning with continued
hydro concerns into the day. The pattern remains active through the
weekend and upcoming week as wave continue to ride across the
thermal ridge in this "ring of fire" set up. Repeated rounds of
convection will rely on earlier rounds for both placement and
strength. A few lulls in convection are possible next week, but
timing out which days this may occur is difficult at this time
range.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 642 PM CDT Wed Aug 12 2026

Primarily VFR conditions prevail over Iowa this evening,
although scattered cumulus around 3000 to 4000 ft does span the
area. Brief light rain and even an isolated funnel cloud have
been reported with this afternoon development, but aside from
that, impacts have been minimal. Later tonight into the morning,
patchy fog will begin to develop over the area.

Through the morning hours, we look ahead to yet another
potential thunderstorm complex moving through the area.
Confidence is fairly high that this complex will track through
Iowa tomorrow morning, but exact timing and intensity remain
less certain. Therefore, have timed out the most likely time
period for thunder in the TAFs, which is a tad later now than
the previous forecasts. Adjustments may be needed as we draw
nearer. Confidence is highest for storm impacts at KFOD and
KDSM, but all sites could be see showers or storms tomorrow morning.
After storms move out, low clouds linger through the day and
scattered showers with isolated thunder persist into the
afternoon hours, mainly over northern and eastern Iowa.

&&

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

&&

$$

SHORT TERM...Hagenhoff
LONG TERM...Hagenhoff
AVIATION...Dodson