textproduct: Des Moines

KEY MESSAGES

- Dying showers over northern Iowa early this morning.

- Dangerously hot conditions persist through Monday.

- Severe weather potential remains tonight, but there is high uncertainty in location and timing of storms.

SHORT TERM /THROUGH MONDAY/

Issued at 1239 AM CDT Sun Jul 26 2026

The remnants of the mesoscale convective system (MCS) is pushing through northern Iowa after blasting the Sioux Falls metro with severe winds earlier this evening. Intensity has waned significantly with no lightning now as the outflow boundary has pushed far ahead of the rain. As this rain continues to diminish across the area, there may be lingering clouds in the morning, which should scattered into the afternoon. With mid-level heights persisting or slightly higher, it will be a sultry day. Forecast soundings show boundary layer mixing that results in higher temperatures and lower dewpoints, especially over western into portions of central Iowa. This has been accounted for in the current forecast. The net result is similar heat index values, which are plus or minus five degrees of 110. Thus, the extreme heat warning for Sunday afternoon continues to look warranted. Additional nudgers is the experimental NWS HeatRisk, which is in the high/level 3 of 4 category over much of our area. Adding to the hot day will be a bit of haziness to the sky due to high level wildfire smoke that will be drifting overhead.

As the sun sets Sunday evening, attention will turn to the high reservoir of instability over the region, especially over eastern Iowa and points east. Deterministic models and CAMs show a variety of solutions with their placement and timing of storms as the low level jet ramps up into Iowa during the evening. Trying to cluster these into similar placement camps, models are trying to have one MCS push south-southeastward through the Mississippi River Valley of eastern Iowa/Wisconsin/Illinois overnight while perhaps another MCS pushes southward through the Missouri River Valley of western Iowa/eastern Nebraska overnight. While none of these peg central Iowa at the moment, the take home point here is the atmosphere can support thunderstorms, which could be severe wherever they track with the main hazard being damaging wind gusts.

With the convective evolution of storms Sunday night still uncertain, this lends to uncertainty in where and how hot the conditions will be on Monday. Looking at mid-level heights, they look to be similar to Sunday if not perhaps a bit less in the global models for Monday. So, right now temperatures and heat index values are a bit lower than Sunday on Monday. Thus, will be looking to adjust the watch to an advisory and perhaps a warning in the coming hours.

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/

Issued at 301 PM CDT Sat Jul 25 2026

As the aforementioned trough deepens as it tracks over the Great Lakes into the Ohio valley late Monday into Tuesday, will see a push of cool air advection into Iowa that will end the stretch of sweltering heat. While temperatures will only be a touch cooler in the upper 80s to low 90s Tuesday, drier air from this shift in low level flow turning northwesterly will allow for slightly lower dewpoints in the upper 60s for most areas. The western thermal ridge overall will move very little through much of the work weak, with any precipitation chances signaled to largely remain west of Iowa until around Thursday, when a more potent shortwave dives southeast on the eastern fringe of this ridge from the Dakotas into Iowa. Certainly room for slight shifts in these larger scale features to occur in the coming days given this being further out in the forecast period, so stay tuned for updates. Highs through the rest of the week remain generally in the upper 80s to low 90s, paired with dewpoints in the 60s, more towards normal summertime averages.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1239 AM CDT Sun Jul 26 2026

Outside of patchy light fog at OTM at present or MCW or ALO later this morning, VFR conditions are largely expected to prevail. There are diminishing showers near FOD, though have removed earlier AMD adjustments that had TEMPO/PROB30 for storms given significant downward trend at MCW/ALO. For Sunday, upper level wildfire smoke will be aloft and have continued high level ceilings for this occurrence.

DMX WATCHES/WARNINGS/ADVISORIES

Heat Advisory until noon CDT today for IAZ004>007-015>017- 023>026-033>037-044>048-057>060-070>073-081-082-092-093. Extreme Heat Warning from noon today to 9 PM CDT this evening for IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075- 081>086-092>097. Extreme Heat Watch from this evening through Monday evening for IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075- 081>086-092>097.