240
FXUS63 KDMX 031130
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
630 AM CDT Sun May 3 2026

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

.KEY MESSAGES...

- Spotty, light showers lingering through sunrise. Then dry and
  breezy with highs in the upper 60s to low 70s.

- Warmer Monday, then a cold front brings showers and
  thunderstorms in the afternoon and evening. Isolated strong
  to severe storms are possible.

- Cooler through midweek with low chances for additional rain
  at times. Frost/freeze potential possible mainly in northern
  Iowa.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 345 AM CDT Sun May 3 2026

Mild conditions are noted across Iowa this morning as temperatures
read in the upper 40s to mid 50s, warmest north where clouds are
more prominent. These conditions are thanks to warm air advection
streaming into the state, with breezy surface winds out of the
south/southwest around 10-15 mph, though higher gusts up to 20-25
mph are occurring over north/north-central Iowa where weak
reflectivity returns are suggesting light rain in the low levels of
the atmosphere trying to make it to the surface. The advertised low
level dry air is largely evaporating the greater majority of these
droplets, leading to this period breezier winds in these areas. This
activity is expected to continue through sunrise before drying
across the state. There is a signal just after sunrise until about
late morning for winds to increase further, particularly over
south central to southeastern Iowa where the lingering presence
of the low level jet is expected to be located. Gusts up to
30-35 mph and isolated to 40 mph could occur at times. Therefore
have increased winds over these areas to account for this
potential, and will need to monitor for more efficient mixing if
any sunshine is able to peak through the clouds, which could
lead for localized and occasional higher wind gusts. As the weak
area of surface low pressure, currently over Minnesota, tracks
east-southeast across the Great Lakes today, its trailing weak
front will enter northwest Iowa around 7-8am, dropping southeast
across the state through the remainder of the morning before
exiting around 1-2pm. Dry conditions for the remainder of the
day, with northwest winds settling overhead and on the breezy
side, with gusts up to 20-25 mph at least through the early
evening before decreasing. Despite northwest winds, warmer air
aloft will keep temperatures on the warm side as highs are
expected to peak in the upper 60s to low 70s. CAM guidance
continues to show redevelopment of showers and even some storms
along the boundary into the evening, though trends keep this
activity over northern/central Missouri. Weak high pressure over
the state tonight into early Monday morning will allow for
light winds and a switch back to southwesterly surface flow,
resulting in morning lows remaining more mild in the upper 40s
to low 50s.

Into Monday, a deepening surface low just above the Great Lakes
region will pass eastward, with its larger 500mb trough and trailing
surface cold front dropping south/southeastward into the Midwest
through the day. For Iowa specifically though, the expectation is
for dry conditions to prevail through the morning and likely through
much of the afternoon, before the cold front passing over the state
develops showers and thunderstorms by late afternoon to evening. A
few things of note in the latest guidance: the first being
timing/speed variations of the frontal passage, and second being the
presence of dry air overhead. Regarding timing, there are still some
differences of note between members, where several CAMs depict the
front draped over north-central Iowa by late afternoon/early
evening, while others such as the RAP and HRRR place the boundary
over far southern Iowa at this same time. However, there is more
consistency of the highest potential for showers and storm coverage
mainly over far southern Iowa into northern Missouri later in the
evening. Regarding dry air as mentioned earlier, model soundings
across much of the area indicate the presence of lingering low level
dry air through the majority of the day, followed by better
saturation of the column occurring late in the day, especially
over southern Iowa where the influence of northward streaming
Gulf moisture extends. Therefore, the overall potential for
showers and storms remains lower (20-40%) into central and
northern Iowa, while highest (50-60%) in the south, especially
near the IA/MO border. Will need to closely watch trends over
the next several runs to better refine these details and overall
confidence in expectations. In terms of overall parameter space
in considering storm development and strength, instability
values around 1000-1500 J/kg, shear values around 35 knots, and
steep lapse rates around 7.5-8 C/km within the warm and stable
airmass ahead of the front (temperatures peaking in the mid 70s
to low 80s and dewpoints in the mid 40s to low 50s, highest
south) are favorable for potential strong/severe storm
development. However, the increasing LLJ generally remains south
of the state, maximized over Missouri late Monday into Tuesday
morning, as well as higher moisture content, leading to greater
instability and forcing for lift in those areas. The Marginal
Risk has been extended further north and east to now include
much of the DMX forecast area. Please stay tuned for updates as
new data becomes available.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 345 AM CDT Sun May 3 2026

Showers and thunderstorms linger mainly over south/southeastern Iowa
into Missouri into Tuesday morning, tracking east/northeastward
along the boundary as this activity moves into Illinois.
North/northeast winds become common across Iowa through the day,
with cooler air allowing for lower temperatures as highs are
expected to return back into the upper 50s to low 60s. Dry
conditions are expected for the rest of the day. Longwave troughing
deepens across the Central Plains to Upper Midwest into midweek,
with generally cooler conditions remaining overhead. Another
boundary setting up somewhere over eastern Kansas into Missouri,
with an increase in moisture and forcing in the same area will
result in additional chances for rain that may extend into southern
Iowa later Wednesday, followed by a quickly passing shortwave across
Minnesota into eastern Iowa/Wisconsin bringing additional low
chances for rain Thursday. Overnight lows into Wednesday morning and
Thursday morning will be on the chilly side, with temperatures in
the 30s to low 40s, coldest north that will be close to freezing.
Will have to keep an eye on this for potential frost/freeze
headlines in the coming days. Will see a shift back to gradual
warming by late in the work week as ridging becomes common across
the western CONUS, with highs through the 60s to low 70s by
Friday/Saturday.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 630 AM CDT Sun May 3 2026

LLWS is expected to remain over KALO, KDSM, and KOTM for a few
more hours before dissipating. Winds however will remain on the
breezy side, with gusts up to 15-20 knots, while KOTM could see
even higher values up to 25-30 knots this morning, decreasing a
bit this afternoon before turning light by the evening. A
frontal boundary arriving into northwest Iowa will pass
southeastward through the morning, leading to winds shifting
from southwesterly to northwesterly. Mid to upper level clouds
streaming overhead will largely remain through the afternoon,
before clearing out by 03-06z. VFR conditions are expected to
therefore prevail across the terminals through the period.

&&

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

&&

$$

SHORT TERM...Bury
LONG TERM...Bury
AVIATION...Bury