498
FXUS63 KDMX 161731
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1231 PM CDT Tue Jul 16 2024

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

.KEY MESSAGES...

- Cooler today with highs in the upper 70s to low 80s. Few
  chances for showers and occasional thunderstorms north and
  west. Severe weather threat is low, but some stronger wind
  gusts possible southwest.

- Pleasant weather takes over through the remainder of the work
  week.

- Additional shower and thunderstorm chances possible west
  through the weekend.

&&

.DISCUSSION...
Issued at 347 AM CDT Tue Jul 16 2024

Following a busy weather day in Iowa, things have finally begun to
quiet down across the state this morning. The surface boundary that
brought severe weather to much of the state tonight has now drifted
south into northern Missouri. Despite the still humid conditions out
there early this morning, cooler temperatures have begun to slowly
fill in behind the boundary. The airmass overhead will steadily cool
and dry out through today and tonight, with highs only reaching the
upper 70s to low 80s today and dewpoints falling into the 60s then
50s by Wednesday.

The airmass change comes thanks to the upper level trough that
continues to dig in from the north and push aside the upper ridging
over the southwest CONUS. This will eventually place us under
surface high pressure through the rest of the week, which will bring
dry and pleasant conditions to the state. However, before this drier
weather occurs, we may see a few more showers and occasional
thunderstorms both north and west today. The northern chances will
be associated with the trough digging south, as a focused area of
mid-level moisture transport pools moisture along an approaching low
level boundary. This feature can be seen producing showers and
thunderstorms over the Dakotas early this morning, and will progress
south into the region this afternoon and evening. The forcing along
the boundary doesnt appear overly strong, but there will be a
decent amount of moisture still present, so any lift that can occur
should be able to produce a few showers today. Fortunately, severe
weather is unlikely with only ~500 J/kg of CAPE within a shallow
layer ahead of the boundary, although a few rumbles of thunder are
certainly possible.

The other area of shower and thunderstorm chances will be over
western Iowa today as a a weak shortwave ejects east out of the high
plains region. This will occur ahead of the aforementioned synoptic
feature, so the environment will be similar for the two areas of
storms, aside from some slightly drier low levels in southwest
IOwa, which may lead to some stronger wind gusts. SPC does have
a marginal risk for severe weather clipping southwestern Iowa
for today, likely for possible wind gusts and in case any of the
better instability to our north or west leaks into the area.
Therefore, aside from a few stronger wind gusts, today`s severe
weather risk looks low at this time, barring any unexpected
movement of the surface boundary to our south.

After today, conditions become quite pleasant through the remainder
of the week. Temperatures will be seasonal in the upper 70s to low
80s with dew points in the 50s, all under mostly clear skies and
light winds. After this much needed break from the heat and active
weather, we may be looking at more thunderstorm chances again going
into the weekend. These will come as a broad upper trough develops
overhead and shortwaves propagate through the roughly northwest to
almost due north flow. That being said, current guidance has this
mainly to the west of the state for now, and the pattern looks
fairly disorganized. Therefore, will continue to monitor weekend
thunderstorm chances in future forecast cycles.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1231 PM CDT Tue Jul 16 2024

VFR stratus has spread across much of central Iowa with a few
spotty showers developing in western Iowa late this morning.
These showers will taper off this afternoon with a secondary
wave bringing additional shower chances to northern Iowa and
KMCW this evening. Otherwise, expect VFR conditions to prevail
through the period.

&&

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

&&

$$

DISCUSSION...Dodson
AVIATION...Hagenhoff