018
FXUS63 KDMX 260734
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
234 AM CDT Thu Sep 26 2024

.KEY MESSAGES...

- Prolonged stretch of quiet and dry weather ahead. Above normal
  temperatures continue through Monday, then a cool down toward
  the middle of next week.

&&

.DISCUSSION...
Issued at 231 AM CDT Thu Sep 26 2024

The forecast period remains largely uneventful with a very
quiet stretch of weather ahead for Iowa. Light winds within a
broad area of surface high pressure and clear skies have
allowed for patchy fog to develop once again overnight, albeit
in a very isolated capacity with only a handful of automated
observation sites reporting meaningful visibility restrictions.
Any fog should quickly dissipate after daybreak this morning.
Deep layer subsidence within a dry airmass will promote abundant
sunshine again today. Highs the previous few days have outrun
the mean NBM guidance, so opted to push highs today toward the
75th percentile of NBM guidance. Similar conditions tonight may
promote additional isolated to scattered fog development.

Synoptic flow aloft is blocked up through the weekend with a large,
closed upper low over the southeast US and the main jet aloft
displaced well to the north. This leaves the local region within the
relatively weak flow regime in between. Expect the status quo with
highs generally around 80 through Monday. Only possible window
for precip arrives as a shortwave trough crosses the Canadian
prairies on Tuesday. While an attendant cold front will bring
more fall-like temperatures the area, much of the kinematic
forcing remains displaced well to the north. The meager synoptic
support will struggle to overcome an atmosphere starved of
appreciable moisture. Still can`t rule out a few diurnally-
driven showers in the cold air advection/steep lapse rate regime
behind the passing front, but even the 90th percentile QPF from
both the GEFS and ECENS show little to no rainfall in the
state. Thus no changes to the dry NBM solution.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1107 PM CDT Wed Sep 25 2024

Little change to the previous forecast with light to calm wind
and clear skies tonight. There remains low potential for fog
towards sunrise. The wind will become east to southeast at 5 to
8 kts by mid morning. Mostly clear skies are expected most areas
though FEW/SCT flat cumulus could develop in the afternoon near
KOTM.

&&

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

&&

$$

DISCUSSION...Martin
AVIATION...Donavon