textproduct: Des Moines

KEY MESSAGES

- Pockets of transient fog are possible this morning.

- Wednesday and Thursday will feature mild temperatures, calm winds, and mostly sunny skies with a few passing clouds.

- A few showers and isolated storms Thursday night.

- Breezy conditions Friday and windy on Saturday.

SHORT TERM /THROUGH THURSDAY/

Issued at 137 AM CDT Wed Oct 7 2026

A subtle cold front and wind shift boundary is currently making its way across the state, sitting NE to SW across the central part of Iowa. This will continue slowly southward through the rest of the night. Some patchy fog is possible early in the morning. Winds have been calming right along the boundary and clear skies are allowing for decent radiative cooling. Additionally, there is some extra moisture near the boundary, visible in subtle shading changes on GOES NT microphysics. However, because the boundary is continuing to move, fog residence time will likely be short for any given spot.

NBM guidance for highs today is generally on the lower side of guidance, and certainly sitting lower than other bias corrected models. Given consistent overperformance of high temperatures, have adjusted highs up 1-2 degrees across the state. However, unlike yesterday, cold air advection is dominant today and 850mb temperatures are 3-4 degrees cooler. Also, cirrus have formed tonight upstream of us and could later limit warming, and this is forecasted by HREF too.

On Thursday the center of a surface high moves across the state. Winds will likely be quite calm during the day. Cold air advection continues until mid day and will cause highs to again be a tick cooler than the previous day. 850mb temps drop to around 9-13C and some cloud cover may be present again. The result will be highs in the low to mid 70s. As the high slides east in the afternoon, 850mb warm air and theta-e advection begins to increase.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/

Issued at 141 PM CDT Tue Oct 6 2026

Return flow will develop Thursday night as the high pressure system moves into the Ohio Valley while Lee side cyclogenesis begins to occur over Wyoming and Colorado. NBM output for PoPs Thursday night have been inconsistent. Most likely, there will be a few showers and isolated thunderstorms around. Proximity sounding sampling of numerous deterministic models suggest saturation will again be a challenge but even shallow saturation in optimal locations in the profile will lead to free parcel lift and modest convective instability. Friday and Saturday will feature an increasing pressure gradient across the Midwest leading to breezy to gusty conditions on Friday. Windy conditions are possible on Saturday with the combination of the pressure gradient approaching 30 ubars/km over the northwest and mixed layer winds near 40 kts. Temperature advection through the profile will be near neutral so mixing efficiency will be average but not as efficient as with cold to strong cold advection. As discussed yesterday, an upper low descending into the Pacific Northwest this weekend will bring a transition from westerly to southwesterly flow to Iowa late weekend and into early next week. The extended forecast beyond that is quite noisy with below average handling of this upper low. The impacts from another upper low lifting out of the south central CONUS and ingested tropical system this weekend appears to remain to the southeast of the forecast area.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 621 AM CDT Wed Oct 7 2026

VFR conditions prevail through the TAF period. Low, but non-zero patchy fog chances exist until 13z this morning and again Thursday morning but impacts are not anticipated unless trends change.

DMX WATCHES/WARNINGS/ADVISORIES

None.