949
FXUS63 KDMX 271123
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
623 AM CDT Wed May 27 2026

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

.KEY MESSAGES...

- Warmest temperatures of the week expected across Iowa today,
  as highs climb into the upper 80s to near 90.

- An isolated shower/storm is possible (10-20% chance) over
  northern Iowa late this afternoon or early evening. No severe
  weather is expected.

- Temperatures remain in the 80s through the remainder of the
  week and weekend. Conditions will be mostly dry, but
  occasional showers or storms could occur at times, mainly over
  western Iowa.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 300 AM CDT Wed May 27 2026

We once again start this morning`s discussion with scattered showers
and occasional thunder over northern Iowa, although this activity
has waned considerably just in the time it took to write this. An
outflow boundary propagating southward had tried to kick off
additional storms just after midnight over north central Iowa, but
it has since outrun the unstable air over northern Iowa and now
wanders aimlessly into central Iowa. Through the morning hours, the
expectation is for rain and occasional thunder to continue to
diminish, although cant rule out at least a rogue shower lingering
to around day break. Regardless, the potential for any severe
weather the rest of this morning is low.

Skies clear out nicely again today, giving way to sunshine and what
looks like will be the warmest day of the week. Highs will approach
the upper 80s over much of the area, with a few locations reaching
or exceeding 90F. NBM seems to have a fairly good handle on the
spread in high temperatures today, with only a 2 to 4 degree
spread between the 25th and 75th percentile temperatures at most
locations. Our relatively static pattern can be thanked for
this tight spread in solutions, as Iowa remains under a broad
area of upper level ridging, sandwiched between a western CONUS
cutoff low and northeastern CONUS trough. At the surface, this
has kept us in weak high pressure with light winds, mostly dry
conditions and ample sun.

A well-mixed boundary layer today will once again produce some
instability primarily over the northern half of Iowa this afternoon
and evening, introducing potential for isolated showers or storms.
That said, with minimal moisture transport to replenish the
atmosphere from rain last night into this morning, storms will have
to squeeze what little moisture is left out of the existing
environment. This lack of available moisture has kept
precipitation coverage fairly minimal in model guidance, and
the forecast reflects this with just a few hours of low
shower/storm chances (< 20%) through the peak heating hours. If
a storm does develop, MLCAPE will generally be around 1000 to
2000 J/kg (depending on the model) but with almost no deep layer
wind shear. A stronger storm could produce some small hail
and/or gusty winds as it precipitates into the dry air below,
but the severe risk is low.

As we go through Wednesday night and into Thursday, our persistent
surface pattern from the last few days will begin to undergo a
slight change. Surface high pressure will begin to build over the
Great Lakes region and it`s influences will begin to spill into
Iowa. Temperatures will begin along a subtle cooling trend, as east
southeasterly low level flow begins to push the the thermal ridge
back west and milder temperatures advect in. That said, the net
result will only be a couple degree change in temperatures, with
highs still reaching the mid 80s on Thursday then low to mid 80s
through the remainder of the week. The building Great Lakes high
will also keep drier air over Iowa, with the main moisture
stream staying off to our south and west through at least
Thursday. There is some potential for light precipitation to
leak into the southwest portions of the state as the moisture
stream oscillates eastward late Thursday into early Friday but
overall the chance for showers or storms looks low with the
surface high pressure overhead.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 210 PM CDT Tue May 26 2026

The upper air pattern is largely unchanged into the weekend
with a plume of instability from the Gulf and through the
plains, skimming western Iowa. This will provide a window for
diurnal thunderstorm development each afternoon and evening
along this axis through Friday and the weekend. Sunday and
especially into Monday the surface high east of the area builds
back, helping to push thunderstorm chances west of the area and
keeping Iowa dry. At this time guidance suggests that this will
remain in place through early next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 620 AM CDT Wed May 27 2026

VFR conditions prevail through the day today. Sunny skies and
light winds will be common at all sites. Predominant wind
direction will be out of the east to southeast, but will vary
through the day. An isolated shower or storm may occur in
northern Iowa late this afternoon and evening, primarily
impacting KFOD or KMCW, but chances are low (around 10 to 15%)
of impacts at a terminal.

&&

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

&&

$$

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