582
FXUS63 KDMX 150455
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1155 PM CDT Tue May 14 2024

 ...Updated for the 06z Aviation Discussion...

.KEY MESSAGES...

- Scattered showers in southeast to central Iowa this afternoon
  taper off this evening.

- Warming trend into the end of the week/weekend with additional
  thunderstorms chances Wednesday evening into Thursday and
  again this weekend. Severe chances remain low at this time.

&&

.DISCUSSION...
Issued at 226 PM CDT Tue May 14 2024

Scattered showers have persisted across southeast Iowa throughout
the day as the surface low continues to slowly swirl to our south.
Another more isolated, and short-lived, shower has developed towards
Boone county with associate more agitated cumulus showing up in GOES
imagery. This has mainly been diurnally driven with just enough
available moisture for isolated shower development. All of
these showers should taper off this evening as the system
finally shifts east.

Wednesday will see a quieter day to start as the next system swings
across the northern Plains towards Iowa. With light winds and
lingering moisture, a few high resolution models have indicated
chances for patchy fog development in southern Iowa on Wednesday
morning though lingering cloud cover may squash this potential. By
evening showers and a few thunderstorms will approach the area
with a front associated with a trough across the central US.
Forcing is weak and focused in the northern and southern
streams that split Iowa on either side. Modest MLCAPE less than
500 J/kg and 0-6km shear at or under 30 kts will limit much in
the way of severe potential. The boundary continues across Iowa
on Thursday with some diurnal restrengthening Thursday afternoon
towards eastern iowa. Even so, the parameter space remains
similar to Wednesday with very skinny CAPE profiles and a very
low severe threat.

The unsettled pattern continues this weekend and into next week
(along with a warming trend), however model solutions diverge with
less confidence in precipitation windows and placement.
Broadly, additional chances exist with a shortwave Saturday into
Sunday. GFS favors a cutoff low bringing precipitation to
southern Iowa Friday night into Saturday, slowing the shortwave
into Sunday. Meanwhile the Euro is more progressive and without
the cutoff low, pushing the shortwave through on Saturday with
less QPF. For now have opted for a middle ground scenario but
will need to fine tune as more data is available. Both also
indicate another more robust system early next week, though
significant differences in timing and placement exist.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1155 PM CDT Tue May 14 2024

Outside of a small patch of MVFR stratus that recently moved
just west of KOTM, VFR conditions were in place across much of
the forecast area. Guidance suggests this area of stratus, with
some fog contributions as well, is expected to expand across
southern IA and into western IA by daybreak, mainly avoiding
any TAF sites. Confidence is not great in this progression
however, with lingering smoke aloft potentially limiting low
level radiational cooling. Mid clouds should increase Wednesday
ahead of the next system, with scattered showers moving west to
east during the evening hours, likely with VFR conditions
through the end of the period.

&&

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

&&

$$

DISCUSSION...Hagenhoff
AVIATION...Small