textproduct: Des Moines

KEY MESSAGES

- Shower and storm chances tonight and Friday morning, followed by the late afternoon and overnight hours over the weekend.

- Below average temperatures Friday and Saturday, followed by highs in the 80s for the remainder of the forecast.

- Frequent shower and storm chances exist in the afternoon and evening times through the week.

SHORT TERM /THROUGH FRIDAY NIGHT/

Issued at 223 PM CDT Thu May 21 2026

Overcast skies covered most of the area today and led to cooler temperatures, some areas not getting out of the 50s this afternoon. The partly sunny fringes have managed to climb into the 60s. Some light showers have formed in southwest Iowa and these will continue to fight the 10-15 degree dew point depression over most of the state. Rain has lagged more tonight arriving in western Iowa after midnight. There could be some rumbles of thunder through the morning. In central Iowa, light showers will be possible in the morning, but then activity will focus on the approaching front to the west. Have lowered PoPs Friday afternoon for central Iowa as saturation is inconsistent and lift is little to none in soundings. Better saturation will arrive towards the end of the day. Thunderstorms will be possible along the front due to CAPE values in the 100-300 J/kg range.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Issued at 223 PM CDT Thu May 21 2026

Mean troughing will continue into the weekend, which keeps the chance of precipitation around at times. Saturday afternoon has trended slightly wetter in the east. This is due to the front from overnight lingering there, and it will have a narrow axis of instability to work with. The highest impact will be lightning, but coverage will be sparse and transient. The thermal ridge will continue to arrive from the west Sunday, but will also be accompanied by more moisture, meaning there will be another chance of showers and storms in the late afternoon and overnight.

In the long term, western CONUS troughing in still favored, but with a more western shift. This centers the eventual blocking pattern over the Plains. There still looks to be a leading embedded closed low in the ridge and it will eventually eject northward into the upper Midwest. The northern stream component of the trough still looks to be a dominant, stagnant feature, churning out segments of energy from the southern stream component. This means that lots of synoptic energy is in play next week, making for a summertime pattern of warm temperatures in the 80s paired with frequent shower and thunderstorm chances at peak heating.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1230 PM CDT Thu May 21 2026

VFR conditions will prevail at least through 10z, with MVFR cigs moving in from the southwest, affecting KDSM, KOTM, and KFOD first. Have added SCT MVFR decks to reflect this, but not confident in BKN to mention at this time. This will be associated with rain that will become more impactful after this TAF period. Have added a Prob30 group for KFOD for showers, but not expecting vsby impacts during this TAF period. Winds will remain easterly with gustiness diminishing in overnight hours.

DMX WATCHES/WARNINGS/ADVISORIES

None.