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343
FXUS63 KDMX 230000
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
700 PM CDT Sun Sep 22 2024

 ...Updated for the 00z Aviation Discussion...

.KEY MESSAGES...

- Light showers ending over the south.
- Next chance of precipitation Monday night and early Tuesday
  far northwest and far southeast.

&&

.DISCUSSION...
Issued at 230 PM CDT Sun Sep 22 2024

Surface cold front is well south of Iowa this afternoon and over
central portions of Illinois and Missouri. Drier dew points continue
to filter into Iowa with values into the low 40s across the north.
Values are still in the upper 50s across the south and there is a
pseudo boundary just south of Interstate 80 now which appears to be
near the edge of the deeper layer dry air.  Some light showers will
persist over the south before the lingering moisture and meager
instability move off to the south.

High pressure ridge will move from the west tonight and into Monday
though mid to upper level clouds over the south will persist. There
is some opportunity for radiational cooling over the north with
temperatures dropping into the lower 40s with a few upper 30s in the
valleys possible. Another short wave will lift through the Midwest
Monday and Monday night with theta-e advection commencing over
southeast Iowa and will bring a chance for a few showers and
isolated storms to that portion of the state. Another short wave
dropping southeast from the Dakotas could also bring a few showers
into northwest and west central Iowa also late Monday night into
Tuesday morning. That system will continue to descend south and
deepens into an upper low over Iowa and Missouri on Tuesday and
will bring the thermal trough over the state. Highs on Tuesday will
be largely dependent on the amount of residual cloud cover the this
upper low. That low will settle slightly father south and stall for
much of the rest of the week while high pressure ridge tries to lean
overtop. Iowa will be stuck in the middle with overall pleasant
conditions with highs in the 70s and lows in the 40s and 50s. Late
in the week and into next weekend, a tropical system is projected to
come on shore over the Gulf coast and become ingested by the larger
upper low, eventually leading to a shift back to the north with a
wave of Gulf moisture lifting into Iowa around next weekend. This is
still a low confidence period but something to watch for the
potential next chance for precipitation.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
-- Changed Discussion --
Issued at 657 PM CDT Sun Sep 22 2024

VFR conditions to prevail through the period with stratus moving
out through the morning for KOTM. Winds will be light and out of
the east/southeast during the daytime.
-- End Changed Discussion --

&&

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

&&

$$

DISCUSSION...Donavon
AVIATION...Jimenez