textproduct: Des Moines

KEY MESSAGES

- Drying out for tonight and mild.

- Showers and thunderstorms become spotty to scattered ahead of a cold front later Wednesday afternoon and night. A few severe storms capable of large hail and gusty winds are possible from mid to late afternoon into early evening.

- Widespread rain chances move back into Iowa later Thursday night into Friday and Saturday leading to mild and perhaps damp conditions for trick-or-treating. Rumbles of thunder also possible on Friday.

- Temperatures remain seasonal if not above normal through the next week.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 246 PM CDT Tue Oct 27 2026

Showers have been dwindling in coverage this afternoon over central into northeastern Iowa as lift weakens within the deeper saturation as the southern stream shortwave pushes towards the western Great Lakes. GOES-East Day Cloud Phase Distinction RGB shows these clouds along with some mid and high level clouds over eastern portions of Iowa into south central Iowa early this afternoon. Farther to the northwest, low water clouds are fairly widespread and while breaks are starting to show up in the cloud deck, RAP cross section show high amounts of low level saturation persisting into tonight. These clouds and where there have been showers have once again kept temperatures below the initial National Blend of Models guidance this afternoon. We currently do not look to contend with fog tonight given increasing or thickening clouds along with winds that stay around or above 5 mph.

Attention on Wednesday will be on the stronger shortwave trough in the northern stream that will be moving through the south central Canadian provinces and the northern US states. Attached to this shortwave will be a southward trailing cold front that will reach the state later in the afternoon and move through our forecast area Wednesday night. Ahead of this front will be breezy southerly winds sustained at 10 to 20 mph with gusts of 25 to 30 mph common. While there could be a few spotty showers in the warm air advection regime ahead of this front, expecting some degree of sunshine that will boost temperatures well into the 70s. These warm and windy conditions will push the cropland fire danger index into the high category (level 3 out of a max of 5). A mitigating factor to fire weather concerns will be that the minimum relative humidity values will stay generally above 50% as southerly winds draw near 60 degree dewpoint into portions of the state.

Spotty to scattered thunderstorms are expected to develop ahead of this cold front with CAPE values up to around 1000 J/kg forecast with good low level kinematics typical of an autumn severe weather set up. The strongest forcing will be closer to the surface low well north of Iowa where QG convergence will be maximized. Lapse rates remain on the weaker side generally below 7C/km and CAPE profiles are rather skinny. However, severe hail greater than 1" in diameter up to perhaps golf ball sized will be possible with a few storms along with gusty winds given the dry mid-level air over northern into western Iowa. This is where convective allowing models show storms developing with some of the more robust models (NAMNest, FV3 cores) having a few to several decent updraft helicity (UH) tracks. The SPC marginal outlook area seems to cover most of these UH tracks, which continues to be supported by the ML/AI/SI guidance. The strongest storms and highest severe potential will wane by mid- evening if not shortly after sunset as storms weaken, but storms will still move across the rest of the area. The front and most of the showers and waning intensity storms will be clear of our forecast area by sunrise Thursday.

As the front sinks and stalls over northern Missouri on Thursday, Iowa should experience a period of dry and warm conditions. This will be short-lived as the next shortwave trough in the southern stream begins to take shape over the southern Plains. Warm air advection will begin to push into Iowa Thursday night ahead of this shortwave, which will result in the return of shower and thunderstorm chances from southern into central Iowa by sunrise Friday.

LONG TERM /FRIDAY THROUGH MONDAY/

Issued at 246 PM CDT Tue Oct 27 2026

While it will not rain continuously, showers are expected from Friday through a good portion of Saturday across many portions of Iowa with peals of thunder likely on Friday as well. There is variability in the models whether this rain will last all the way through Saturday or if Saturday starts to turn drier or if Sunday morning will have lingering showers as well. Regardless, trick or treaters will encounter mild conditions and perhaps damp ones as well Friday or Saturday evening depending on when the festivities are held. Quickly following this southern stream wave will be a more pronounced mid-level trough or closed low that will push over the Rockies by the start of next week and into the central part of the country by the middle of next week. While there is uncertainty in the exact mid-level pattern evolution early next week, confidence is increasing in another round of showers and thunderstorms in this timeframe. With this being one of several rounds of rainfall spread out over the next week with total rainfall between 1.5 and 2.5 inches over the state from the grand ensemble, some within bank rises are possible on mainly smaller streams and tributaries to the larger rivers according to recent runs of the National Water Model forced by the NBM and GFS.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1206 PM CDT Tue Oct 27 2026

Main challenge this issuance is the MVFR/IFR cigs across the region. Clouds will continue to focus over northern Iowa through the period, but have trended more towards MVFR in the extended due to cloud coverage remaining steady state so far today. Rain will taper of with low confidence in vsby restrictions over the next 6 hours. VFR conditions are expected at KALO/KDSM/KOTM through this TAF period. Winds will become uniform out of the south and exceed 10kts after 15z.

DMX WATCHES/WARNINGS/ADVISORIES

None.