939
FXUS63 KDMX 241727
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1227 PM CDT Sat May 24 2025

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

.KEY MESSAGES...

- Showers over central and southern Iowa tonight into Saturday morning

- Rain chances diminish tomorrow then additional rain expected Saturday
  night

- More rain chances move through the area on Monday, but severe
  weather looks low at this time.

&&

.UPDATE...
Issued at 343 AM CDT Sat May 24 2025

Showers and a few strikes of lighting within them waned overnight
due to the shortwave and moisture axis diving southeast. What`s left
is the stratus cloud debris that will hang on for several days. As
mentioned in the discussion below, another shortwave will ride the
northwest flow and recover some moisture advection back into at
least the southwestern portion of the state. The setup is not all
too dissimilar from yesterday, however a key difference is the low
level easterly wind rather than stagnant flow. This will introduce
more dry air than seen yesterday, delaying and limiting the
precipitation seen. Aside for a few lingering sprinkles in the
daytime, most all of the rain will fall after sunset. A surface high
incoming from the Dakotas will reinforce dry air and light flow on
Sunday. There will continue to be sprinkles falling from the column
with not much in the way of accumulations due to the lack of
forcing, most of this occurring in southern Iowa. Less than 50% of
Hi-res guidance even picks up a hundredth Sunday afternoon in the
south. Better chances for rain along with thunderstorms arrives
Monday with a series of two waves developing into a closed low.

&&

.DISCUSSION...
Issued at 241 PM CDT Fri May 23 2025

Northwest flow continues to dominate the upper level pattern
today, with surface high pressure persisting overhead and to our
north. Despite the building ridge and increasing moisture from
the west, cloud cover and precipitation has been fairly minimal
today. Most of the cloud cover has been confined to the
southwestern corner of the state, and even then has mostly burnt
off. That said, a shallow layer of instability developing at
the top of the mixed layer has begun to produce some shallow
cumulus clouds oriented from northwest to southeast along the
periphery of the trough in central Iowa. This same location will
be the point of focus this afternoon, as a weak shortwave and
coincident mid-level moisture makes its way east across the
forecast area this afternoon and evening. As this occurs,
moisture convergence will increase aloft, saturating the layer
and producing scattered showers through the region. That said,
efficient mixing today and minimal low level moisture advection
into the already dry air mass will lead to a dry sub-cloud layer
for showers to precipitate into. Rain evaporating as it falls
will limit rainfall amounts realized at the surface and may lead
to some locally breezy winds with the showers. With the dry air
mass in place to our north and east, precipitation chances also
decrease further north and east in the state. Aside from a
slight increase in winds (~15-20 mph), not expecting any
hazardous weather with little to no instability present tonight.
If lightning occurs anywhere, it will be in southwestern Iowa
and would be isolated.

Light showers begin to diminish in coverage early Saturday
morning and measurable rain chances from this round of showers
ends by 12z Saturday. That said, could still see an isolated
light shower or sprinkle through mid-day. Cloudy conditions and
mild temperatures continue through Saturday afternoon and are
followed by more scattered shower chances as weak forcing and
marginal moisture remains overhead. The best rain chances still
look to be over the southwestern half of the state, but some
short-range guidance indicates a band of rainfall again
developing in north central Iowa similar, to what we may see
tonight. Tomorrow nights rain chances are struggling more with
forcing and saturation, so confidence in rain occurring further
north is low. Even then, these would still be fairly light rain
chances with no threat of thunderstorms or severe weather. Rain
chances last into at least Sunday morning, with some lingering
precipitation in southern Iowa through mid-day Sunday.

As we get into the Memorial Day holiday on Monday, an upper
trough building to our west lifts north and east into the state,
bringing rainfall with it before it eventually merges into a
closed upper low just north of the state. This will continue our
wet and mild pattern through Monday and Tuesday. Fortunately,
with guidance depicting very low instability with the wave, the
risk for widespread severe weather appears low at this time.
That said, will continue to monitor for any hazardous or
impactful weather early next week, especially with the holiday
on Monday. Through the remainder of the work week, the upper low
remains parked to our north, potentially bringing additional
rain chances through mid- to late week as well as some steadily
warming temperatures on the backside of it.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1219 PM CDT Sat May 24 2025

VFR conditions prevail through the rest of today and into this
evening. Clouds will increase overnight as light showers make
their way into the area. Confidence is fairly low on the
coverage of these showers, but have depicted the most likely
time periods in TAFs. Lightning is unlikely, but can`t rule out
a strike or two. Will update TAFs if lightning appears imminent
at a terminal. Low cloud cover also moves in from the south
early tomorrow morning, leading to MVFR and potentially IFR
ceilings Sunday morning.

&&

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

&&

$$

UPDATE...Jimenez
DISCUSSION...Dodson
AVIATION...Dodson