935
FXUS63 KDMX 230517
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1217 AM CDT Mon Sep 23 2024

 ...Updated for the 06z 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 /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1217 AM CDT Mon Sep 23 2024

Few impacts this period. H500 mb trough to track across Iowa
through period with return of moisture southeast leading to
lowering cigs and potential for some light showers aft
20z at OTM which will continue through 06z. Remainder of the
region will remain with high clouds while the southeast/south
will be BKN/OVC030 to 110 aft 18z through 06z. Small chance OTM
may see brief period of MVFR aft 00z as the band of showers
moves through. Winds light and variable through the period and
under 6kts. /rev

&&

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

&&

$$

DISCUSSION...Donavon
AVIATION...REV