textproduct: Des Moines

KEY MESSAGES

- Dry conditions through Monday with highs in the 80s.

- Fog possible in eastern and southeast Iowa tonight into Monday morning.

- Widespread thunderstorm chances Tuesday and Wednesday with a Slight Risk of Excessive Rainfall.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 251 PM CDT Sun Aug 2 2026

High pressure dominated the weather this afternoon and will keep conditions dry and winds light. Highs this afternoon will be in the low 80s with plenty of sun. Fog will make a return tonight and be mainly shallow, but will fill in more in the east and southeast. Places like Ottumwa may see some reductions in visibility for the Monday morning commute. Light winds will be replaced by steady southerly flow Monday afternoon. Highs will return to the mid and upper 80s in the south and west through Tuesday.

LONG TERM /TUESDAY THROUGH SATURDAY/

Issued at 251 PM CDT Sun Aug 2 2026

A cold front will trail along a negatively tilted upper wave near the US-Canada border and has trended slower to exit over Iowa. Heavy rain is the main concern as PWATs rise above 1.5" and flow points parallel to the front's orientation. While CAPE totals over 1000 J/kg both Tuesday and Wednesday afternoon, the saturation of the profile keeps lapse rates closer to the moist adiabat, presenting an elongated and skinny CAPE profile. Uniform parcel acceleration will favor heavy rain over hail and the weak shear profile will make any wet microburst potential in storms relatively short-lived. The severe weather risk is low for these reasons on both days, but a Marginal and Slight Risk ERO have been issued. Rainfall will peak in the evening and overnight hours with deterministic runs all painting a band of 2"+ in northern and central Iowa. Given present convective processes highlighted above, would not be surprised if localized amounts over 5" are realized. Amounts will be better understood as the system enters the CAM window.

For hydrology impacts, soil moisture in northern and northwest Iowa is low (5-20%) and can take the most rain. National Water Model simulations using GFS QPF have most of the river responses in eastern Iowa where antecedent conditions are comparatively more wet. Only the high-end basin QPF outputs bring basins such as the Cedar into Flood Stage, so the chance for this is low (5%). For flash flood potential, Iowa is in peak crop maturity which further diminishes concerns for rural parts of the state. Concerns increase if the axis of heavy rain falls on an urban area.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1242 PM CDT Sun Aug 2 2026

MVFR cumulus affecting KALO for the next 2-3 hours, but will lessen in coverage through the afternoon. SCT clouds near KOTM with lower confidence in MVFR in the short term. Added in VFR fog mentions for KOTM in the early morning hours. Higher confidence in MVFR/IFR to the east of the site where more rain fell the past few days. Will refine in later issuances. A secondary terminal to watch for a fog mention later is KALO, but confidence is too low to add for now. Moisture will lift to a low cumulus deck through the morning and will bring opportunity for MVFR cigs intermittently.

DMX WATCHES/WARNINGS/ADVISORIES

None.