Des Moines forecast discussion

Short Term /Through Saturday/

Issued at 254 AM CDT Fri Oct 16 2026

Short wave trough is passing through Iowa currently with a cold front approaching the state as well over Minnesota and South Dakota. Surface low pressure is over Michigan with a broad area of stratus and some showers extending west and just behind the upper level trough passage. The main forecast challenge this morning will be the wind gusts and if they reach advisory criteria. The pressure gradient will continue to increase this morning and maximize this morning over north central Iowa around 35 ubars/km. The primary pressure height rises will be to the north of the state but will also clip across northern Iowa. The mixed layer depth this morning while the max 925-850 mb winds are passing by though is less certain. Model Sounding profiles remain mostly saturated through this layer with cloud bases around 1500 ft and this is aligning well with the bases currently over southern Minnesota. Some cold advection will be occurring but that will be limited by the moist profiles during this period. The another source of subsidence is the mid-level descent behind the upper level energy, which is further back upstream and will arrive as the mixed layer winds are diminishing. The current wind gusts upstream are mostly below 35 kts. A few higher gusts have been associated with area with rain showers. Those showers will move across the north and east this morning so will continue to monitor and at this time, will hold off on wind headlines. May need a Special Weather Statement if the higher gusts continue with any rain showers and will reconsider an advisory if it becomes more widespread.

The wind will begin to diminish this afternoon and should get some breaks in the stratus over northern Iowa by mid to late afternoon as high pressure ridging approaches from the west. Profiles should quickly decouple around sunset leading to the wind further diminishing. Overnight low temperatures are the challenge for the overnight. A big factor in the challenge for temperatures overnight is the shallow cold layer near the surface with a relatively steep inversion just 500-700 ft off the surface. This type of a steep and low inversion can prove difficult for surface temperatures to fall off too much. Factoring in the new wet ground and also still warmer, and the ground itself won't cool quickly. The wind also may not completely go calm with the high center off to the southwest so some uncertainly on the level of radiational cooling that can be achieved. Despite the uncertainty, big picture for Iowa, still expect several areas to reach freezing or below, especially north and west and widespread frost for most areas. Coldest temperatures will be rural with warmer areas in the larger metros including Des Moines where frost is expected even if freezing temperatures are not achieved. Coordinated a transition from the Freeze Watch to a Warning and as noted above, some areas may not reach freezing but this will be the first cold impacts of this Fall season. Saturday will be mostly sunny and will become breezy from the south as return flow arrives. Highs will be in the mid to upper 50s.

Long Term /Saturday Night Through Thursday/

Issued at 254 PM CDT Thu Oct 15 2026

Surface high pressure gradually moves into the region Friday night into Saturday morning allowing winds to drop off, skies to clear, and good radiational cooling. Temperatures by Saturday morning fall into the upper 20s to low 30s. A Freeze Watch has been issued for Saturday morning to account for these low temperatures so make plans now to protect any sensitive vegetation! The pressure gradient tightens again Saturday behind the departing high pressure leading to breezy winds, especially north, Saturday into Sunday. Conditions otherwise remain dry with the surface high and an upper ridge in place. Temperatures begin to rebound later Saturday into Sunday as southwest flow returns translating to gradually increasing highs this weekend into early next week. Highs in the 50s Saturday become 60s Sunday-Monday and 70s again by Tuesday. There are a few hints of a small system near the region around Monday night but our forecast remains dry until mid to later next week when there is a bit more consensus for returning precipitation chances though details will continue to be refined in the coming days.

Aviation /06Z Tafs Through 06Z Saturday/

Issued at 1059 PM CDT Thu Oct 15 2026

Intermission of VFR cigs to start, but MVFR stratus is on the way from the northwest in the next 6 hours. Added Prob30 mentions for showers at KALO in the morning. Also added gusts into the Prob30 groups as winds could be higher with precip. MVFR departure was delayed for all sites, especially north. Gusts over 30kts common between 12 and 18z.

Dmx Watches/Warnings/Advisories

Freeze Warning from 1 AM to 9 AM CDT Saturday for IAZ004>007- 015>017-023>028-033>039-044>050-057>062-070>075-081>086- 092>096. Frost Advisory from 1 AM to 9 AM CDT Saturday for IAZ097.

SHORT TERM...Donavon LONG TERM...05 AVIATION...Jimenez