351
FXUS63 KDMX 061947
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
247 PM CDT Sat Jun 6 2026

 ...Updated for the 18z Aviation Discussion...

.KEY MESSAGES...

- A few isolated storms may develop this evening along a
  boundary in far southern Iowa. The severe threat is low,
  however these thunderstorms could produced gusty wind or
  hail.

- Widespread showers and thunderstorms will lift out of
  Missouri and spread across Iowa on Sunday morning and continue
  off and off throughout the day through Monday morning. The
  severe threat is low, however they may produce pockets of
  heavy rain. This could be impactful for areas that have
  already received heavy rain the last few days.

- Warm and humid conditions build this week with many areas
  exceeding 90 degrees by mid-week.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 247 PM CDT Sat Jun 6 2026

Conditions cleared out quickly this morning with abundant sunshine
across Iowa this afternoon. Temperatures have warmed into the low to
mid 80s across the state. A boundary is draped across southern Iowa,
just north of the southern two tiers of counties, noted by a wind
shift in surface observations and a pool of high dewpoints along and
south of the boundary. With daytime heating instability is
increasing in this area with 2000-3000 J/kg of CAPE. This is the
area to watch for possible diurnally forced convection late
this afternoon into the early evening hours. There is very
little effective bulk shear (10-15 kts) available to organize
any storms that do try to develop. As such, isolated pulse
thunderstorms are expected along this boundary that will go up
quickly and then just as quickly collapse, resulting in mainly a
wind hazard. DCAPE values are quite high at 1500+ J/kg. SPC has
maintain a narrow marginal risk (level 1 of 5) for the wind
threat in southern Iowa this afternoon/evening.

Overnight theta e advection increases out of Missouri and into
Iowa and an upper level closed low moves across the midwest.
Associated widespread showers and thunderstorms will also spread
across the state Sunday morning. With multiple pushes of theta
e advection expected, showers and thunderstorms will last off
and on though much of the day. Soundings are quite saturated so
severe storms are not expected, however heavy rain will be a
concern. PWATS are at 2+" with warm cloud depths of 4000+ m,
allowing for efficient rain production. A widespread 1-2" of
rain is expected, though hi- res guidance indicated pockets of
2-4" are possible. Southern Iowa received heavy rain Friday
night and will be susceptible to flooding should these heavier
totals fall there. WPC has issued a Slight Risk (level 2 of 4)
for flood potential on Sunday. Rain lasts overnight and taper
off across eastern Iowa Monday morning.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Issued at 247 PM CDT Sat Jun 6 2026

This week thermal ridging builds across the area with a western US
trough ejecting bits of vorticity into the midwest, providing
opportunities for precipitation. In this weak flow regime
consistency amongst model guidance is low, as the GFS  indicates an
MCS across northern Iowa on Tuesday while the EC waits until Tuesday
night and placement is across most of the state. The main trough
will pass across Iowa Wednesday into Thursday, providing the
next window for more organized storms. SPC has outlined a 15%
risk area here for Wednesday as the trough moves across Iowa.
Even here the GFS is slower compared to a more progressive EC
solution.

While synoptic evolution is less certain this week in this weak flow
regime, increasing heat and humidity is more certain as the thermal
ridge builds. The NBM remains on the high end of the guidance
envelope, but has started to come down a handful of degrees. With
plenty of moisture in play, warm and humid conditions will prevent
deeper mixing needed to achieve the mid 90s the NBM was
progging. Even so, upper 80s to low 90s with dewpoints in the
upper 60s to around 70 will make it feel quite muggy this week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 247 PM CDT Sat Jun 6 2026

Isolated thunderstorms are possible in far southern Iowa late
this afternoon into early evening, however at this time these
are expected to remain south of KOTM so have kept from TAF at
this time. Then SUnday morning showers and thunderstorms will
spread across Iowa from south to north, continuing off and on
throughout the day. Have timed expected onset time with
prevailing -SHRA and prob30 -TSRA through Sunday morning. This
timing may be refined in later updates. This will reach KMCW
near 18z at the very end of the current period, thus no mention
was included at this time and will be added in future issuances.


&&

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

&&

$$

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