513
FXUS63 KDMX 101919
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
219 PM CDT Thu Sep 10 2026

.KEY MESSAGES...

-  Patchy fog possible overnight /mainly SE/ otherwise
   seasonally cool.

-  Breezy Friday afternoon, with a chance for showers and
   thunderstorms /20-40%/ returning Friday night.

-  An active weather pattern expected this weekend into the middle
   of next week with periods of thunderstorms, some strong to
   severe, along with the risk of heavy rainfall.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 1255 PM CDT Thu Sep 10 2026

A drier, northwest upper flow pattern will continue into the
overnight hours, with sfc high pressure over Iowa. A few high
clouds remain over the region, but all in all a rather pleasant
evening is in store with temperatures falling into the 70s and
modest humidity.

The sfc high will translate eastward overnight as a sfc low develops
over the Dakotas. The latest statistical and ensemble guidance
continues to suggest the potential for patchy fog development
over the far southeast tonight, where winds will decouple the
longest. Stronger sly sfc flow should preclude any fog
development further north/west. Lows tonight will be seasonally
cool in the 50s/60s.

The pattern changes tomorrow as an upper shortwave slides across the
Dakotas and into Minnesota on Friday into Friday night. The
associated sfc low will follow the same general trajectory,
pulling a cold front across IA overnight. Breezy southerly
winds will develop ahead of the sfc low, strongest in northern
Iowa, where gusts over 30 mph will be possible tomorrow
afternoon. These winds will bring a plume of higher moisture
northward, however the axis of best instability is expected to
remain along the Missouri River into MN through evening. Weak
forcing, limited moisture, and capping will keep conditions dry
areawide through at least Friday evening. Consensus of the
global and CAM guidance continues to suggest scattered showers
and elevated thunderstorms developing along the southward
sagging cold front, which will move into the northwest sections
of the CWA after midnight, and eventually into the far south
sections of the CWA by early Saturday AM. There remains a very
conditional risk of strong/severe storms across NW IA /Level 1
and 2/, where the shear and SRH profiles remain most favorable
for severe weather. However, model soundings show the
environment remaining strongly capped /MLCIN over -150 J/kg/,
thus the highest potential for severe weather will remain north
and west of the DMX CWA.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 1255 PM CDT Thu Sep 10 2026

The latest guidance continues to suggest quite an active
pattern across much of the Midwest, including Iowa, from this
weekend into the middle of next week. There will be a risk for
strong to severe storms at times along with heavy rainfall.

Saturday...
Lingering showers and storms along the cold front are possible
on Saturday morning, mainly across far southern Iowa. Severe
weather is not expected. Depending on the location of the sfc
boundary, storm re-development is possible again Saturday
afternoon/evening. Most of the 12Z guidance suggests the front
will push into Missouri on Saturday afternoon, with the
strongest sfc based instability confined to the south. However,
a few deterministic models /e.g. NAM/ do show elevated
instability values over 1000 J/kg developing Saturday afternoon,
so there remains a conditional risk for strong to severe
storms. Additional elevated storms are possible Saturday night
into early Sunday, but there is low confidence on the
orientation and strength of the low level jet.

Sunday into Wednesday...

Periods of showers and thunderstorms are likely on Sunday into
Wednesday as a series of shortwaves move across the area. In
addition, a strong LLJ is expected remain very active during the
period, most notably on Sunday night and Monday and again on
Tuesday night. While mesoscale details are likely play a large
role in the convective evolution each day, the deterministic
models/ensembles along with various NCAR AI guidance and the
ECMWF Extreme Forecast Index remain consistent in showing both
the potential for severe weather /Monday/ and heavy rainfall
from Sunday through Wednesday. Correspondingly, the SPC
currently has a Day 5 Slight Risk for severe storms and the WPC
has noted multiple days of Marginal/Slight via the Excessive
Rainfall Outlooks (EROs). Again, its too early to get into
specific details during this period but 7-day rainfall amounts
in excess of 3-4" are certainly possible with GEFS showing
probability of 2" > 50%, and a 10-20% of greater than 4+". This
could lead to areas of areal or river flooding, especially if
the higher end of the rainfall distribution occurs.  More to
come on this in future days.


&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1220 PM CDT Thu Sep 10 2026

VFR conditions are expected the remainder of today, with only
high level clouds, or few diurnal cumulus present. Winds will
remain generally light and variable, but will gradually shift
out of the southeast this evening. Tonight, expecting patchy
fog to develop in southeast Iowa, only impacting KOTM where the
winds will be lightest. At the remaining terminals, winds
should increase enough to preclude any fog development. Breezy
south winds will develop towards the end of the period Friday,
mainly at northern terminals.

&&

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

&&

$$

SHORT TERM...Fowle
LONG TERM...Fowle
AVIATION...Fowle