518
FXUS63 KDMX 061748
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1248 PM CDT Thu Aug 6 2026

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

.KEY MESSAGES...

- Dense fog this morning over portions of northern, central, and
  western Iowa. This fog will dissipate by mid-morning. Patchy
  drizzle in central and southern Iowa early this morning also.

- Potential for another round of fog tonight, particularly over
  eastern Iowa.

- Storm chances return at times from Friday into early next
  week, but not an all day washout by any means. Potential for
  strong to severe storms and locally heavy rainfall Friday and
  Saturday.

&&

.UPDATE...
Issued at 645 AM CDT Thu Aug 6 2026

Dense fog advisory was expanded over southern Iowa given recent
visibility drop in those areas. There was some consideration to
removing some counties along US 30 (Boone to Marshall) as well
as Black Hawk. However, ALO dropped to 3 miles and nearby
webcams show fog. Therefore, will allow the area to continue for
a bit longer before cancelling any counties.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 301 AM CDT Thu Aug 6 2026

Dense fog has become widespread over portions of Iowa as forecast
with GOES-East Nighttime Microphysics picking up on this as a
faint, light blue north of the low clouds, which are a cyan hue.
A Dense Fog Advisory has been issued through mid-morning for
areas that are expected to have visibilities at or under a
quarter mile between now and sunrise. Will be monitoring the
stratus` evolution, Iowa DOT webcams, and surface observations
for any possible expansion, including southward towards the Des
Moines metro. Beneath this stratus and as shown in soundings
there is a saturated layer with a depth of about 1.5 km, which
has created drizzle here at our office and on some Iowa DOT
webcams earlier. Otherwise, the main area of thunderstorms
associated with the front that brought our storms last night are
closer to I-70 in Missouri early this morning.

After the fog dissipates after sunrise by mid-morning, will see
decreasing clouds over at least northern Iowa with lingering
clouds until this afternoon over southern Iowa. Areas that do
become clear may see diurnal cumulus generate with boundary
layer daytime heating. Highs will be a several degrees below
normal for early August around 80 degrees. There may also be
some lingering high level wildfire smoke aloft, mainly over
western and southern Iowa. Into tonight, a mainly clear sky,
generally light winds outside of northern Iowa, and the recent
rainfall point to another night of fog potential, particularly
for areas east of I-35. Dense fog is possible over our eastern
forecast area along the US 63 corridor and points east;
however, fog is fickle and will monitor trends in guidance.
Drizzle potential tonight looks less likely with the depth of
saturation around a 500m.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 250 PM CDT Wed Aug 5 2026

The relief from rain will be fairly short lived as an active weather
pattern sets up. An upper-level ridge sets up in the desert
southwest and locks Iowa in northwest flow for the remainder of the
forecast period. We start seeing effects on Friday when moisture
returns. Severe weather is possible Friday when storms fire on the
instability gradient with 40kts of deep-layer shear to work
with. Will need to monitor for supercell potential as the shear
orientation is orthogonal to the boundary. If supercells
materialized, the hail threat increases due to most of the shear
residing above the inflow layer and the steepening lapse rates
from the reestablished EML. The front will reorient itself for
Saturday, but severe weather will remain in play as instability
quickly recovers and deep-layer shear remains favorable across
the state.

Northwest flow continues into next week with multiple chances
for thunderstorms and high temperatures heavily dependent on
storm placement. This pattern continues into next weekend, as
highlighted by the CPC 8-14 day outlook.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1240 PM CDT Thu Aug 6 2026

MVFR cigs have lingered into the early afternoon hours, but are
starting to break apart, so have reflected them with TEMPO
groups. Fog likely again tonight with dense fog most likely at
KOTM. Vsbys have been trended lower to reflect and MVFR/IFR cigs
are included for stratus that would eventually lift. Showers and
storms will approach KFOD at the conclusion of the period, but
with uncertainty remaining in intensity.

&&

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

&&

$$

UPDATE...Ansorge
SHORT TERM...Ansorge
LONG TERM...Jimenez
AVIATION...Jimenez