468
FXUS63 KDMX 281938
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
238 PM CDT Thu May 28 2026

.KEY MESSAGES...

- Temperatures will fluctuate from the low to mid 80s today
  through the weekend.

- Scattered shower and storm chances begin Friday afternoon in
  the southwest (20-40%) and slowly expand eastward Friday night
  into Saturday.

- Rainfall totals across most of the state will be low (<0.1"),
  but potential exists for isolated pockets of heavy rain.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 133 PM CDT Thu May 28 2026

Checking back in with the slow moving shortwave/MCV today shows it
has meandered northward from Texas to Kansas in the last 24 hours.
It brings with it a decent fetch of gulf moisture and saturated
profiles, mainly staying to the southwest of our CWA. However, some
ascent from the shortwave has brought cirrus clouds across Iowa and
helped to hamper highs today, though are still on track for mid 80s.
Advection of dry air from the Great Lakes high pressure should keep
precip chances in check through the rest of the day. This battle of
airmasses, high pressure and dry air to the northeast and a moisture
plume to the southwest, will be the focal point for forecast
uncertainty over the next several days.

Since yesterday, guidance has trended towards a stronger push from
the shortwave, likely cutting further into Iowa Friday afternoon
into Saturday. This will bring PWATs exceeding an inch into
southwest and central Iowa. A more certain implication will be
additional cloud cover during peak heating tomorrow, leading to
highs several degrees colder than previously expected, likely in the
upper 70s and lower 80s. The mid and upper levels will be near
saturation, leading to chances for showers after midday particularly
in southwest Iowa. However, dry air below 800mb will be persistent,
and should limit QPF to less than a tenth of an inch in most
locations. A stronger push of moisture will be brought in Friday
night as the shortwave nudges east, and this is where certainty
decreases. A band of rain with some embedded convection may set up
somewhere over Iowa through the night, but exact location and impact
from lingering dry air is uncertain for QPF amounts. Chances for
severe weather is low, though ~500 j/kg of CAPE may support thunder
chances.

A comparable pattern looks to hang on through Saturday, though
confidence is low on how far thunderstorms may make it into Iowa.
Some solution have even suggested rainfall making it into eastern
Iowa. Latest NAM3km and RRFS brings 1000-2000J/kg of SBCAPE into
western Iowa, possible supporting more robust convection on
Saturday. Mid and upper level shear will still be low, but late may
remnant MCV type environments tend to modify the low level shear in
unexpected ways. Regardless, the severe weather threat looks low
with these storms, and the larger impact is actually the potential
for isolated regions of heavy rain. QPF across the state as a whole
may not even exceed a tenth of an inch, but any storms that do form
will be moving exceptionally slow. There are a few outlier NBM
members that have precip totals Friday/Saturday over two inches in
central and southwest Iowa. Pinpointing exactly if and where this
may happen is difficult at this time.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Issued at 133 PM CDT Thu May 28 2026

Uncertainty in the long range is high as the trough in the west is
trying to eject, shortwaves around the western fringe of the eastern
Canada longwave trough are pivoting south, and remant central US
shortwave will dissipate or merge with the next shortwave.
Regardless, as the western trough attempts to eject, it looks likely
southerly flow will bring a more robust warm sector into or near
Iowa. Latest GEFS guidance brings moderate CAPE into Iowa by Sunday
and Monday. On a large scale, period of thunderstorms look possible
in the long term. EPS/GEFS position Iowa atop a decaying ridge and a
shortwave off the the west, making weak to moderate shear possible.
Any severe weather through the period will become highly contingent
on mesoscale details, particularly convective evolution closer to
the shortwave further west, and require more model certainty to
untangle.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1230 PM CDT Thu May 28 2026

There are no aviation concerns through the TAF period. Only
high clouds are forecast (above FL100), with modest breezes
slowly turning from east to southeast through the period.

&&

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

&&

$$

SHORT TERM...De Bruin
LONG TERM...De Bruin
AVIATION...Lee