300
FXUS63 KDMX 131940
AFDDMX

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


.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 /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1248 PM CDT Sun Jul 13 2025

Unseasonably dry air mass to keep VFR conditions in place at
area terminal through this forecast cycle. A few of the computer
simulations suggest the possibility of an isolated shower or
weak thunderstorm across southern MN late tonight, however do
not expect them to reach northern IA nor KMCW. Winds will remain
generally from the southeast at 5-10 knots through the period.

&&

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

&&

$$

DISCUSSION...Hahn
AVIATION...Hahn