126
FXUS63 KDMX 231724
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1224 PM CDT Sun Mar 23 2025

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

.KEY MESSAGES...

- Light showers this morning with an isolated storm southeast.
  Gusty northwest winds by this afternoon (few gusts to around
  45 mph at times, mainly north)

- Weak system late Monday night/Tuesday (light shower chances
  25 to 35%)

- More organized multi-day event later in the week Wed night
  into the weekend with rain chances (70 to 80%) during the
  systems peak. Warmer as well.

&&

.UPDATE...
Issued at 1055 AM CDT Sun Mar 23 2025

H850 cold air advection has increased behind the upper level low
enough to create an area of rain/snow mixed over north/central/west
with some snow around Rockwell City in a small deformation axis
forming over west central Iowa. Temperatures remain near the
rain/snow mix changeover, so not sure how long this will stay
mixed prior to changing back to rain. None the less, have
updated for a small portion of this area to reflect the change.
/rev

&&

.DISCUSSION...
Issued at 259 AM CDT Sun Mar 23 2025

Widespread warm advection is underway early this morning ahead of a
shortwave dropping into western Nebraska.  Despite good lift over
the state, precipitation has been very spotty as moisture remains
limited over Iowa.  The bulk of precipitation/convection has
developed in eastern KS and over Missouri on the theta-e advection
nose.  This moisture does work northward over the next several hours
with strong 850mb flow of 45-50kts.  As the moisture entrains into
the system over Iowa, showers are expected to develop and increase
in coverage around daybreak into the morning hours.  The best
coverage remains east of Interstate 35 where the deeper moisture
resides but overall rainfall amounts should remain light. Otherwise,
a boundary slides across the forecast area during the morning with
the rain threat ending as the boundary passes.  Strong subsidence on
the backside of the front along with cold advection is expected to
produce windy conditions into the afternoon over central Iowa and a
Wind Advisory remains in effect across the northwest where the
highest gusts are anticipated. Most soundings indicate less than
advisory criteria elsewhere although the GFS soundings are much more
robust but is the odd model out at this point.  Of other concern
will be elevated fire danger across the southwest by this afternoon
as relative humidity values drop to around 30 percent along with the
strong winds.  All concerns drop off this evening as mixing
decreases with sunset allowing the wind advisory to drop off and
improving fire weather conditions.

Upper flow remains from the northwest through midweek as the current
system passing through Iowa evolves into a broad eastern trof
by early in the week. Relatively quiet weather is expected into
Monday as surface ridging slides into the state. A shortwave
approaches from the northwest on Monday night into Tuesday
morning. Lift and moisture are more limited with this weak
system and any precipitation looks to be light and scattered.
The upper pattern begins to transition by the later half of the
work week as upper ridging slides into the central United State
ahead of a system approaching the west coast. Warm advection
intensifies into Thursday and Friday along with increasing
theta-e advection. Both GFS and Euro have elevated convection
pushing across Iowa on Thursday as the theta-e advection focuses
into the state. Thereafter, southerly flow deepens with very
warm air and increasing moisture into the state for Friday and
Saturday. The deterministic models diverge at this point with
Euro bringing and negatively tilted trof across the state late
Saturday. This would likely bring a good chance of convection
and potential severe weather. The GFS is more of an elongated
trof across the central US which still provides for a threat of
storms but perhaps not as potentially threatening as the Euro
solution. Still plenty of time to see how this system evolves
over the next several days.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1224 PM CDT Sun Mar 23 2025

Overhaul to earlier thinking with mesolow rotating through DSM
at this time. MVFR/IFR cigs possible near mesolow at DSM and
extended longer in time this afternoon. Enough dynamics to add
some snow into the forecast along with brief period of winds
gusting over 40 mph through 19z central and eastern areas prior
to 20z. Winds will continue mixing this afternoon as skies thin
aft 21z with gusts continuing to 30kts through 00z many
locations. /rev

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 7 PM CDT this evening for IAZ004-015-023-
033-034-044-045.

&&

$$

UPDATE...REV/Jimenez
DISCUSSION...Cogil
AVIATION...REV

NWS DMX Office Area Forecast Discussion