458
FXUS63 KDMX 151729
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1229 PM CDT Wed May 15 2024

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

.KEY MESSAGES...

- Chances for showers and thunderstorms increase late today into
  tonight for much of central Iowa. Severe threat remains low.

- Warmer on Friday into Saturday with very limited chances of
  precipitation.

- Active pattern appears to be emerging into next week with
  several chances for showers and thunderstorms.

&&

.DISCUSSION...
Issued at 357 AM CDT Wed May 15 2024

Iowa was between system overnight with scattered cloudiness around
the state along with relatively light winds.  Low level moisture
trapped near the surface has led to an area of expanding stratus in
southern into western Iowa this morning and is advection west to
northwest in the southeast low level flow.  Farther northeast, the
airmass is a bit drier and skies have remained mostly clear along
with cooler temperatures.  Precipitation which was approaching the
state overnight has mostly dissipated across eastern Nebraska. These
were ahead of a boundary which was slowly passing east through the
Plains.  The associated shortwave progresses gradually east today
with mid level forcing increasing into western Iowa by this
afternoon into the evening.  Instability also increases with daytime
heating although the low level wind fields remain relatively light,
therefore overall shear is rather paltry.  Scattered showers and
storms should fire by mid afternoon and progress into western and
central Iowa by late afternoon into the evening.  Support for severe
storms is minimal given the weak shear profiles with localized heavy
downpours the main concern.  The activity gradually passes through
the forecast area overnight with little fanfare.  Redevelopment is
possible by midday on Thursday in the eastern forecast area, however
most of the activity should quickly pass out of the area as the
boundary continues eastward.

Some uncertainty remains on Friday across southeast Iowa with
regards to some light precipitation.  GFS has some precipitation
with an ejecting shortwave through Oklahoma into southern Missouri
and is generally at odds with other guidance.  Low PoPs will still
remain in the far southeast on Friday although it appears little
rainfall will materialize.  Elsewhere, warmer conditions are
forecast along with quiet weather.  Thermal ridging slides into the
state early on Saturday ahead of an approaching boundary with warm
temperatures expected during the day.  The front is expected to pass
through during the afternoon with a few isolated storms during peak
heating, mainly along and east of the Interstate 35 corridor.
However, the bulk of lift associated with this system remains much
farther north into Minnesota and Canada.

Next week appears to be rather active with a broad west southwest
flow across the central United States.  Moisture is generally
available with mostly unimpeded flow off of the Gulf.  Placement and
timing of systems remains somewhat suspect at this time although
both GFS and Euro output suggest some convection impacting central
and southern Iowa by Sunday night.  Thereafter, a series of system
ejects from the west and pass into the region with on and off
chances for storms which may include the threat of some severe
weather along with heavy rainfall.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1229 PM CDT Wed May 15 2024

VFR conditions currently prevail across the forecast area. -SHRA and
some embedded -TSRA will move west to east over the state from late
this afternoon through tonight. Highest chances generally reside
across northern Iowa, so have included mention of -SHRA/VCTS for now
to cover the potential, however the extent of categorical impacts, if
any, will need to be further evaluated since confidence is low at this
time.

Low cigs push into MVFR range toward Thursday morning, but should
not last long as improvement is noted in most model guidance by late
morning or early afternoon.

&&

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

&&

$$

DISCUSSION...Cogil
AVIATION...Martin