398
FXUS63 KDMX 121849
AFDDMX

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

.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 TUESDAY/...
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 /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1252 PM CDT Wed Aug 12 2026

Morning storms have exited east of the area with skies clearing
quickly behind. Scattered cumulus may develop this afternoon
but VFR conditions are expected. Overnight storms will reach
western Iowa, moving across Iowa in the early morning through
the end of the TAF period. Confidence in occurrence is fairly
high and -TSRA was included at all sites, but timing and
location could shift and adjustments in later issuances are
possible.

&&

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

&&

$$

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