textproduct: Des Moines

KEY MESSAGES

- There is a Marginal Risk for severe weather for late Monday into Monday night, including after dark. Damaging winds and a tornado or two may be possible.

- Rain and storms remain possible Tuesday. Rain chances extend into Thursday for at least northern Iowa.

- Highs cool midweek with highs in the 40s possible for northern Iowa.

SHORT TERM /THROUGH TONIGHT/

Issued at 142 AM CST Mon Nov 2 2026

A deep 500 MB trough is moving eastward over the Rockies early this morning, preceded by several shortwave impulses that are ejecting out into the central U.S. The first such shortwave is moving over Iowa at this time and generating a broad swath of light showers moving from west to east across our service area. Another shortwave will move overhead this afternoon, then the core of the trough will approach western Iowa late tonight. Meanwhile, at the surface southeasterly flow covers the region and the near-surface layer is saturated with widespread low ceilings blanketing most of Iowa. This is keeping overnight temperatures quite warm for the season as they are held up by dewpoints in the mid to upper 50s areawide.

Regional radar imagery indicates that behind the leading swath of light showers, which is moving across western and central Iowa at this writing, scattered showers have developed across much of Nebraska and Kansas, mitigating expectations of a lull in precipitation later today. It seems more likely that behind the first push of light rain, we will continue to see occasional showers for much of the day. That being said, as the synoptic surface front approaches the Missouri River valley late this afternoon and evening, a narrow dry slot preceding it may work into our western counties and allow for some modest destabilization. The parameter space for most of today is not favorable for severe weather with ample shear but very limited instability. As we progress toward the end of the day and into tonight, however, a surface cyclone will deepen over central/eastern Kansas as the main 500 MB trough axis moves over the High Plains. Instability will increase ahead of this surface low within a region of increasingly favorable low-level shear profiles and thunderstorms developing in eastern Kansas will rocket northeastward across Iowa mainly after dark tonight. Forecast soundings indicate strong low-level and deep-layer shear and increasing low-level instability with 0-3 KM AGL CAPE reaching 175-200 J/KG in our southwestern counties roughly between 02Z and 08Z or so. There are also signs of modest mid- level drying during that time, and these environmental conditions would seem to favor a threat of both severe straight-line winds and tornadoes. However, the big fly in the ointment is the degree to which the near-surface environment will or will not be realized. The same forecast soundings persistently depict a shallow saturated and stable layer will persist, with modest surface lapse rates around 5.5 C/KM. The most likely scenario is one in which showers and thunderstorms move across our forecast area tonight, but remain elevated and thus far less capable of producing severe weather. SPC outlooks depict this well with only a Marginal Risk over the southwestern half or so of Iowa, however, we will be closely monitoring today and tonight in case it appears the environment may become more favorable for surface-based convection, in which case the tornado and wind threats would increase accordingly.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 141 PM CST Sun Nov 1 2026

The stalled upper low will sink towards Iowa on Tuesday and its dry slot will rode the midlevel clouds and allow for some of the stratus to mix out. The cold front will exit the area in the early morning and add to the mixing potential with CAA. Post-frontal storms will be possible as low-level lapse rates steepen and will contribute to the gusty winds that afternoon. Storms could trend stronger if the dry slot comes more north into the state, allowing for lapse rates in the midlevels to steepen out once more. Wednesday and Thursday have trended colder. This is because the upper low will park right over Iowa Wednesday and all but guarantee stratus and rain until the TROWAL departs late Thursday. Highs may very well trend down and into the 40s. Highs will recover back into the 50s and 60s once the flow resumes a southerly component.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 520 AM CST Mon Nov 2 2026

Low clouds will blanket most of the area through the TAF period, producing widespread IFR ceilings, occasionally dipping to LIFR or rising to MVFR. Periodic SHRA/TSRA are also forecast for much of the next 24 hours, but have attempted to use TEMPO/PROB30 groups only during the most likely time windows for rain reducing visibility. With prevailing IFR ceilings and intermittent MVFR or lower visibility for much of the next 24 hours, expect amendments to TAFs based on short-term radar and observational trends.

DMX WATCHES/WARNINGS/ADVISORIES

None.