633
FXUS63 KDMX 311133
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
633 AM CDT Mon Mar 31 2025

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

.KEY MESSAGES...

-Strong to severe storms possible late Tuesday evening into
Wednesday; Snow Chances North Tuesday

-Near Advisory level winds expected Tuesday and Wednesday with
warmer temperatures

-Dry Thursday, followed by possible continued active weather into
the weekend

&&

.DISCUSSION...
Issued at 353 AM CDT Mon Mar 31 2025

Quiet weather prevails across Iowa early this morning, as any
remaining drizzle and light wintery precipitation previously
overhead has ended with the low pressure system now lifting across
the eastern portion of the Great Lakes. Northwesterly flow has kept
temperatures on the cool side through the nighttime hours, with
values in the 30s under partly cloudy skies. High pressure over
Canada into the Dakotas is expected to track southeast across the
region through the day, which will keep dry and quiet conditions
today. Expect mostly sunny skies with high temperatures remaining on
the cool side into the 40s north and in the low 50s south.

Around sunrise through the morning hours Tuesday, the low level flow
pattern makes a shift to increasing southerly flow, which will be
rather strong with 50-60 knot winds at 850mb. With an increasing
signal for these low level winds to mix down to the surface at
times, have increased values in coordination with neighboring
offices. Winds by the late morning through the afternoon are
expected to reach gusts over 40 mph across the CWA, which are
largely similar for Wednesday as well. Warm and moist air will
therefore make a return into midweek with values reaching into the
60s. An increase in forcing for lift, in association with the warm
air advection wing ahead of an approaching deepening low pressure
system, is slated to move over Iowa into Minnesota Tuesday morning.
While the main band of lift generating precipitation looks to remain
largely into Minnesota, portions of northern Iowa may see a wintry
mix and snow by mid-morning, before turning to rain early Tuesday
afternoon. RAP soundings depict a saturated column with temperatures
largely below freezing, though values in the surface in the upper
30s to low 40s should allow for melting to occur with more of a wet
slushy snow to rain. However, the NAM is colder with temperatures
below freezing throughout the column, putting snow as the main
precipitation type. Overall, any snow accumulations should be on the
lower end, with values around or less than an inch. Frontogenesis
looks to be maximized further north into Central Minnesota, where
the bulk of much higher snowfall amounts are expected. Further south
with this initial band of precipitation over central Iowa into
portions of western Iowa, temperatures above freezing will allow for
any precipitation to fall as rain, though dry air in the low levels
may prove to be difficult for much to actually reach the ground, so
will need to keep an eye on trends. As the large low pressure system
tracks northeast into the Midwest, a frontal boundary per model
guidance looks to enter western Iowa Tuesday evening and track
eastward across Iowa through the night and into Wednesday morning.
This front with a strong low level jet setting up ahead of it into
the late evening and early Wednesday will lead to an increasing
potential to see strong to severe storms. Soundings indicate steep
mid-level lapse rates around 8 C/km, along with favorable
instability around 1500J/kg of MUCAPE and effective shear values
around 30-35 knots, which is all supportive of a rather large hail
threat as well as gusty winds. These storms overall look to be
elevated given the presence of a rather prominent near surface warm
layer. The Slight Risk area that is highlighted by the SPC has been
expanded slightly further north to account for the larger favorable
area where severe weather is possible, highlighting potential
hazards well.

As any lingering showers and storms exit the area through Wednesday,
models signal a chance for some wrap around rain showers with the
departing low pressure system at least over northern Iowa until
Wednesday afternoon. Dry weather returns across the state into the
evening Wednesday and Thursday as high pressure settles over the
Central Plains, bringing cooler air overhead. Highs Thursday will
reach into the upper 40s north and in the upper 50s south. Late
Thursday into Friday, long range model guidance shows a shortwave
tracking out of Kansas/Nebraska into Iowa, followed by another
system developing over the Southern Plains. Differences between the
GFS and Euro still are quite noticeable, as the GFS keeps the
activity south of Iowa due to a blocking high pressure system in the
Central Plains limiting its movement into the region, while the Euro
depicts a more defined low pressure system with its northern fringe
tracking into the state Saturday. Will need to keep a close eye on
this over the next few days as more details come to light and more
model guidance captures this system in question.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 633 AM CDT Mon Mar 31 2025

VFR conditions are expected throughout the TAF period across the
terminals. Mid to upper level clouds are expected at times today
and into Tuesday, with slightly breezy northwest winds gusting
to 15 knots. Winds change direction to more southeasterly flow
towards the end of the period, and gradually increasing.
Widespread cloud cover returns ahead of the next system Tuesday,
with chances for rain or snow starting just beyond the current
TAF period.

&&

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

&&

$$

DISCUSSION...Bury
AVIATION...Bury