textproduct: Des Moines

KEY MESSAGES

- Mostly dry period over the next 7 days.

- Seasonal temperatures through the period with modest warming mid to late next week.

- A few periods with overnight/early morning fog are possible.

SHORT TERM /THROUGH TONIGHT/

Issued at 150 AM CDT Sat Oct 3 2026

The upper level pattern has evolved to a roughly zonal flow per RAP analysis with GOES-East upper level water vapor imagery showing a low amplitude wave moving east of the northern Rockies. At 700mb, there is an axis of saturation from the Red River Valley of the North into parts of northern Iowa, which has fostered clouds in this region per Nighttime Microphysics RGB imagery. Similar to last night, there have been a site or two intermittently reporting fog and this may continue through sunrise. Otherwise, temperatures have fallen into the low 50s or 40s as of 130am.

For today, the upstream low amplitude wave will dig and deepen as it moves towards the state. There will be waves of strong theta-e advection and QG convergence, especially in the low levels north of the state. However, cross sections and forecast soundings agree there is a significant dry layer between 900 and 800mb. This will keep central and southern Iowa dry. Over northern Iowa, the saturation in the column is more, but it still seems the better forcing is out of sync with the higher saturation. This hasn't stopped a few models from kicking out light QPF over northwestern Iowa this morning and then later this afternoon and evening over north central and northeastern Iowa. However, our forecast will remain dry for the aforementioned reasons. Soundings once again show decent boundary layer mixing through the day, though perhaps not to the extent that occurred on Friday. Still, lowered dewpoints a few degrees toward the 50th percentile and also increased wind gusts given the increased pressure gradient with potential for mixing stronger winds aloft to the surface. This had the biggest impact to the wind gust forecast over northern Iowa.

For tonight as the shortwave trough departs the region, any clouds over northern Iowa will clear. Winds across much of central Iowa will remain elevated between 7 and 10 mph and this will keep fog concern mostly muted. However, over southeastern Iowa winds are lighter and 3z RAP soundings does show a brief period of saturation for fog. That said, the RAP is the only model showing this saturation as the NAM, GFS, and HRRR are drier at the surface so will monitor trends through the day to see if patchy fog needs to be added.

LONG TERM /SUNDAY THROUGH FRIDAY/

Issued at 218 PM CDT Fri Oct 2 2026

Sunday through much of next week will feature modified westerly flow across Iowa. This pattern will feature mild days with cooler nights and similar to seasonal conditions for early October. Highs will be in the 60s and 70s with overnight lows in the 40s and 50s. The forecast is also mostly dry and should allow the area to dry out with occasional breezy days helping to accelerate the evaporation and drying of the ground surface.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1220 PM CDT Sat Oct 3 2026

VFR conditions otherwise are expected through the period across all sites. Breezy conditions will remain across the forecast area over the next several hours, but especially across the northern sites where gusts up to 25-30 knots have occasionally occurred from the south/southwest, before decreasing around 00z. Otherwise, will see some upper level clouds pass through, mainly over northern Iowa through the evening, with a very low chance (<10%) for a light shower north. Some signal remains for patchy fog over parts of southern Iowa, but confidence in occurrence is quite low, so have left out and will continue to monitor.

DMX WATCHES/WARNINGS/ADVISORIES

None.