063
FXUS63 KDMX 131750
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1250 PM CDT Sun Jul 13 2025

 ...Updated for the 18z Aviation Discussion...

.KEY MESSAGES...

- Departing smoke eastward this morning

- <10% chance of showers and storms in northwest Iowa this
  evening. Low chances again in the northeast on Monday
  afternoon.

- More widespread chances for showers and storms arrives by
  midweek.

&&

.UPDATE...
Issued at 258 AM CDT Sun Jul 13 2025

Another fairly quiet morning across Iowa, though some isolated fog
has been occurring on and off over northeast Iowa, which brought
visibilities below 2 miles at Mason City early this morning but has
since improved. Conditions are expected to remain favorable for on
and off isolated areas of patchy fog, which would result in reduced
visibilities over northeast Iowa, as the latest HREF indicates
through at least sunrise before dissipating. Otherwise, quiet
weather is expected across the state today, outside of a very low
chance for showers and a possible storm or two in far northwestern
Iowa. Compared to model guidance yesterday, CAMS have trended down
on any activity even reaching into the CWA as a boundary tracks into
eastern South Dakota into far northwestern Iowa and southern
Minnesota. Therefore, PoPs have been reduced further over the area
to <10%. A look at the parameter space with this boundary overall
depicts favorable shear and instability to aid in storm development
further west and north of Iowa this evening. However, a Marginal
Risk was introduced that does reach into Emmet County, suggesting
the potential for at least an isolated severe storm, but the overall
potential is very low. Will have to closely watch trends through the
day, but given the minimal coverage area and trends limiting
development into Iowa, the concern for hazardous weather is very low
for the evening at this time.

Lingering smoke this morning is also expected to move out of the
area over the next several hours as the high pressure over the
Midwest tracks away from the region, with the low level flow
pattern turning more southwesterly.

&&

.DISCUSSION...
Issued at 245 PM CDT Sat Jul 12 2025

The low-level moisture fetch has been shoved to the south and east
this morning, leaving little for the passing wave to the northeast
to tap into. We`re left with some midlevel cloud debris as well as
smoke in the upper levels. Some of this will reach the surface
via post-frontal subsidence this afternoon near the IA-MN state
line, but much of this will miss much of IA and instead be
carried around the high pressure center and back towards the
north. There is another weak wave that will dive into the
Central Plains from Colorado this afternoon and reinforce the
block of Gulf moisture along with the redirection of smoke
mentioned earlier.

The aforementioned central Plains wave keeps the low-level moisture
away from the area for at least the first half of the week, but it
will also put the state in northwest flow and open us up to a series
of waves from Canada. The LLJ will also reemerge into the
Northern Plains later on Monday. It will intersect with a system
that is forecasted to impact Minnesota, later dragging its cold
front (and the main moisture axis) across Iowa on Tuesday night
into Wednesday. This front will then stall somewhere near
southern Iowa, hence the broad rain and storm chances for the
remainder of the week.

&&

.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.

&&

$$

UPDATE...Bury
DISCUSSION...Jimenez
AVIATION...Hahn