861
FXUS63 KDMX 120508
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1208 AM CDT Mon Aug 12 2024

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

.KEY MESSAGES...

- Showers and thunderstorms this evening and overnight to
  Monday morning. Additional precipitation chances Wednesday
  into Thursday.

- Gradual warming back towards seasonal averages this week.

&&

.DISCUSSION...
Issued at 231 PM CDT Sun Aug 11 2024

A weak wave off to the west has resulted in increasing cloudiness
across the area this afternoon while southeast flow has helped nudge
temperatures a degree or two over yesterday. Meanwhile, the primary
vorticity lobe across the northern plains will drop southeast
this evening and across Iowa overnight and into Monday morning.
Instability is quite modest, with HREF mean MUCAPE under 500
J/kg into Iowa and CAM soundings showing the same. While shear
is 40-50 kts, it will be difficult for stronger storms to
develop in this low instability environment. The primary QPF
axis will sweep across southern Iowa with HREF noting a swath of
1-3" possible in this area. Most rain will taper off around 12z
Monday morning, however a few CAMs note lingering spotty
showers across the area with trailing weak forcing as the
system lifts east.

Temperatures gradually warm into midweek as the western US thermal
ridge gradually rebuilds and influences the area. This will send
temperatures back into the low to mid 80s, nearer seasonal
averages for this time of year. The pattern becomes more active
by the middle of the week as a more robust wave deepens across
the central plains and moves across Iowa Wednesday into
Thursday. Solutions diverge with the synoptic evolution as the
EC remain more progressive while the GFS slows and deepens into
a cutoff upper level low over the area that lingers into Friday.
As it stands the severe threat is low, however with variability
in possible solutions this is low confidence. What is more
consistent is the heavy rain potential with weak flow and good
moisture transport into the area. Deep warm cloud layers will be
in place and models indicate PWATs of 2+" Wednesday into
Thursday. High pressure looks to build into next weekend,
helping to dry things out.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1205 AM CDT Mon Aug 12 2024

Showers and a few embedded thunderstorms south expected for the
next 6-8 hours. MVFR cigs expected to coat southern terminals
through the morning, lingering at KOTM until the early afternoon
hours. Have removed IFR mentions due to decreasing confidence in
this possibility. Have modified VCTS FM groups to reflect times
of highest confidence for thunderstorms for KDSM and KOTM. Have
left out of KFOD due to low confidence. Prevailing VFR expected
after 21z.

&&

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

&&

$$

DISCUSSION...Hagenhoff
AVIATION...Jimenez