613
FXUS63 KDMX 091142
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
642 AM CDT Tue Jun 9 2026

 ...Updated for the 12z Aviation Discussion...

.KEY MESSAGES...

- Patchy fog northeast early this morning.

- Hot and humid today. Heat Advisory in effect for much of the
  southwest half of the state. Heat indicies of 100-105
  expected.

- Several rounds of storms are forecast from late tonight
  through Thursday night. Severe storms are possible, with the
  strongest storms expected on Wednesday. Large hail, damaging
  wind gusts, and tornadoes are all possible on Wednesday.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 326 AM CDT Tue Jun 9 2026

All is quiet over Iowa early this morning with the main storm show
moving out of Kansas and into Missouri. Although there are storms
over western Nebraska early this morning as well, these are
expected to dissipate as they cross Nebraska so the forecast
remains dry through much of the daytime today. High clouds
associated with the activity to the south have moved into the
southwest half or so of the state with clearer skies to the
north and east. With light winds ongoing, patchy fog has been
able to develop in portions of our far north/northeast. Although
visibilities in these areas may drop near to below 1/2 mile at
times, not expecting widespread sub 1/2 mile fog precluding the
need for any fog headlines this morning. This cloud cover moves
off to the east by about mid morning with clearing expected
behind. South to southwest flow ramps up into this afternoon
ushering in ample moisture advection as well as hotter
temperatures. Forecast highs are in the 90s for much of the
area, with the coolest temperatures in the northeast where cloud
cover may hold on longest and hottest in the west where the
most clearing is expected as well as the proximity to the
thermal ridge. With the high dew points in the 60s to 70s, heat
indicies climb to the 100- 105F degree range in much of the
southwest half of the state where a Heat Advisory is in place
today from midday to mid evening.

Any cloud cover that develops or moves in could potentially spoil
the extent of the heat but largely expecting the daytime to be dry
with storm development largely inhibited due to a mid-level warm
layer. Some CAMs do try to kick off a few storms this afternoon to
early evening in our deeply unstable environment characterized by
2000-4000 J/kg of MLCAPE but through the afternoon the better shear
is offset from the higher instability and as just noted, forecast
soundings suggest a cap to be in place. What seems most likely is
storms develop over the Dakotas ahead of the approaching upper level
trough this afternoon with upscale growth into a MCS expected to
occur into the evening and move eastward with time late evening into
the early overnight hours. What remains unclear is if this MCS will
impact Iowa or not. Many CAMs keep it mostly north of the IA/MN
border but certainly can`t rule out this MCS bringing thunderstorms
with gusty winds to at least portions of the area late tonight into
the early overnight with a 40-60 knot LLJ pointed to our west
through eastern NE so should storms make it into NE from the line in
the Dakotas, this could certainly help sustain them. As noted in the
SPC Day 1, the MCS is generally expected to weaken with eastern
extent but certainly this will be something we`re watching closely
into Wednesday morning.

Then attention turns to Wednesday. Some early day showers or storms
are certainly possible in the warm air advection wing. A low over SD
early moves north through the day but brings a cold front with it
that will start to cross the area on Wednesday afternoon before
stalling out on Thursday. This is in tandem with the approaching
upper level support which finally crosses through the area on
Thursday. Gradient winds become gusty on Wednesday with the warm
sector pointed right through the area, an open Gulf, and shear
finally catching up to the ballooning instability with MLCAPEs again
by afternoon around 2000-4000 J/kg and bulk shear of anywhere from
30-45 knots by afternoon and even greater by evening as the jet
kicks in. This environment will support all modes of severe weather
from large hail, damaging wind gusts and tornadoes. The strongest
tornado and largest hail potential rides with any storms that form
earlier in the event and can become sustained supercells which at
this point is northeast into east central Iowa (for locations in
Iowa). With the aforementioned increasing jet, we may be looking at
multiple rounds of storms with some in the afternoon and evening,
and then another round developing late. Will also need to watch for
another developing MCS to the west which could bring even more
storms into early Thursday morning. Locations of any early day
outflow boundaries or other mesoscale details could certainly alter
locations of features developing. This is similarly true on Thursday
as what occurs Wednesday night may affect the location of the
stalled out boundary and any lingering outflows though we are
certainly looking at another day of storm development in the warm
sector which at this point remains over at least the southeast half
of the state.

We will also need to continue to monitor the hydro threat in
especially southern Iowa where soil moisture remains higher and
heavy rain occurred in the last week. Pwats remain near to over 1.5-
2" through this week.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 259 PM CDT Mon Jun 8 2026

The pattern remains on the active side Thursday, with lingering
showers and storms mainly over southern and eastern Iowa as the
frontal boundary gradually departs the state. A brief reprieve is
indicated later in the morning, then another surface low over
Southern Plains within the larger western CONUS trough moves into
the region. Latest model guidance such as the NAM shows that this
system tracking directly over Iowa Thursday afternoon through the
evening, with warm frontal showers and storms indicated during the
morning followed by additional activity later in the afternoon into
the evening. Severe weather looks possible with this activity as
well.

Following the frontal passage, dry conditions look to return for
some time. The upper level low pressure is signaled to deepen
further as it circulates over the Upper Midwest into Canada. This
flow pattern overhead will lead to slightly cooler and less humid
conditions, with highs in the low to mid 80s and dewpoints in the
50s. Long range members begin to diverge more by the weekend, as the
GFS keeps conditions on the dry side before the next system arrives
later Sunday, while the Euro passes a few subtle waves across Iowa
that keep at least low chances for showers/storms at times. While
variations like these are normal this far out, details should become
more clear in the coming days, so stay tuned for that.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 634 AM CDT Tue Jun 9 2026

Patchy fog early this morning in the northeast affecting KMCW
and KALO is expected to dissipate shortly after sunrise. VFR
conditions are largely expected to follow today with high clouds
gradually clearing this morning before more clouds move in
tonight, though at this point VFR conditions still prevail.
Confidence in storm development today is very low through much
of the evening with the highest chances (though still less than
40%) late tonight into the overnight hours and in
northwest/northern Iowa. However, timing and impacts of storms
at any terminals remains quite uncertain given the uncertainty in
storm development. Thus, took out/kept out any precipitation
mentions with confidence in all cases less than 30%. Light and
variable winds this morning will settle out of the south and
increase into tonight sustained around 10-20 knots and gusts to
around 20-25 knots.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 1 PM this afternoon to 9 PM CDT this
evening for IAZ015-023-033>035-044>048-057>062-070>075-081>086-
092>097.

&&

$$

SHORT TERM...05
LONG TERM...Bury
AVIATION...05