858
FXUS63 KDMX 132330
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
630 PM CDT Sun Jul 13 2025

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

.KEY MESSAGES...

- Patchy fog possible in far southern Iowa late tonight & early
  Monday

- Muggy conditions return to start the week with dew point
  temperatures rising back to near 70F

- Next widespread chance (40-60%) of rain returns to the region
  beginning late Tuesday night and continuing into Thursday.

&&

.DISCUSSION...
Issued at 240 PM CDT Sun Jul 13 2025

The anomalously dry air mass (PWAT of 0.71" on OAX`s 00z
sounding puts it in just the 10th percentile per SPC`s
sounding`s climatology) that made a brief appearance yesterday
and today disappears quickly tonight as moisture advection and
typical mid-summer Iowa humidity returns to begin the week. As
this begins, short-range CAMs consistently depict a decaying
low-level boundary and weak convection initiating & dropping
thru S MN late this evening and overnight. However, unable to
sustain moisture enough to overcome the drier air mass, no
solutions sustain this activity into northern sections of the
CWA. So for now - will keep silent precip chances across the far
north. Additionally, added patchy fog mention in far southern
Iowa late tonight & early Monday as clear skies combine with
light winds to narrow dew point depressions to near saturation.

Flow turns zonal for Monday & southwesterly for Tuesday as the
pattern buckles ahead of the next wave moving into the Pacific
Northwest. Continued low-level warm-air thermal advection both
days will push afternoon highs back into the upper 80s to near
90F. In the absence of any forcing the bulk of both days will
remain dry. However, it`ll feel noticeably muggier both days as
surface dew points return back to around 70F.

By Tuesday night, the first shortwave kicks out into the
region, bringing perhaps a MCS and next shot of moisture into
the state late. The boundary will remain in the vicinity for
Wednesday and into Thursday. This will be our best window of the
week for widespread precipitation. Another week, another shot
at several inches of rainfall. Deep layer shear makes a return
as well during this period as right entrance of upper-level jet
moves across the state. This will aid convective organization
through the period. Any severe potential will be refined in the
coming days as the mesoscale details can be resolved.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 630 PM CDT Sun Jul 13 2025

Upper level smoke continues to pass across central to eastern
Iowa with some making it to the surface and diminishing
visibility. KDSM has reported visibility under 10 mi this
afternoon and expect this through this evening until it shifts
further east. Further north, isolated showers and thunderstorms
are expected from South Dakota into Minnesota overnight. These
may approach KMCW but at this time do not expect impacts to the
site. Later on, patchy fog is possible Monday morning, mainly
in southeast Iowa. Have held off on mentions at KOTM but will
monitor trends for future updates.

&&

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

&&

$$

DISCUSSION...Hahn
AVIATION...Hagenhoff