textproduct: Des Moines

KEY MESSAGES

- Heavy rain concerns have largely diminished, but rain remains common through late Monday night. New rainfall amounts generally up to a half inch.

- Fog also possible Monday morning, bringing visibility impacts to the morning commute.

- Cool, dry weather expected for the midweek. Next chances of rain creep into the west late in the period.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 145 PM CDT Sun Sep 20 2026

Northeast flow advected in dry air near the surface today which chewed away at some of the drizzle/fog that was common last night and this morning. What was left was a blanket of stratus and lingering pockets of mist in southern Iowa. More low-level stratus could be seen incoming from the north on satellite. At the synoptic level, an embedded closed low was analyzed over Wyoming, its presence leading to some southerly flow and convection in the High Plains. Highs this afternoon likely won't leave the 60s thanks to the solar insulation, save for far southeast Iowa.

Tonight, theta-e advection will battle against easterly flow from a high near the US-Canada border. Backed winds at 850 will converge along this dry flow which will be enough convergence for showers and a few storms in northern Iowa, but the reduced moisture transport has reduced our concerns for heavy rain. On to Monday, an embedded closed low will move across the state and be met with a secondary vort max from behind. This forcing will be enough to keep precipitation going, but as the high positions itself over the Great Lakes, its influence will increase, putting a limiter on available moisture for the forcing to summon. Cumulatively, this time period will amount to two tenths of an inch to perhaps half an inch in northern Iowa where both rounds are most likely. Fog will build in for Monday morning with visibility reductions common once again.

Temperatures Monday will be some of the coolest this week. Highs may reach 60 degrees, but much of the state will be in the upper 50s.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 145 PM CDT Sun Sep 20 2026

High pressure will skirt along the US-Canada border and east of the Great Lakes with time. As a result, Iowa will keep an easterly fetch. Upper-level ridging will keep us dry until it's broken down at the end of the week. Until we get there, the main theme this week will be partly cloudy skies and highs in the 60s, a timely pattern change for the autumnal equinox. A couple of disturbances will move onshore and set up an active weather pattern for next weekend with rain chances inching their way into western Iowa.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 636 PM CDT Sun Sep 20 2026

Widespread IFR to MVFR cigs and vsbys are occurring over parts of central and southern Iowa while KMCW/KALO will begin the period VFR. Expect conditions will gradually deteriorate overnight as the IFR/MVFR areas expand northward. Drizzle and continued lowering of vsbys is expected along with some areas reaching LIFR. Showers and possibly a few thunderstorms may become possible during the day Monday especially near KFOD/KDSM. Some slight improving conditions may arrive near KMCW late.

DMX WATCHES/WARNINGS/ADVISORIES

None.