textproduct: Des Moines

KEY MESSAGES

- Dry and relatively cool today, then temperatures falling tonight and reaching the 30s in northern and eastern Iowa where a frost or freeze may be possible early Monday morning.

- Warmer temperatures will return for most of the coming week, along with some shower and thunderstorm chances (25-35%) late Monday night into Tuesday. A few strong storms could be possible, but the severe weather threat is limited.

- Breezy conditions are forecast on Tuesday, especially in northern Iowa during the afternoon where wind gusts to near 40 MPH are expected. Dry conditions will also continue during this time, with Relative Humidity falling below 25% at times.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 238 AM CDT Sun May 10 2026

A large high pressure area will build southward into the region today, bringing dry and somewhat cooler weather. Some mid-level clouds may develop at times, but in general skies should remain partly to mostly sunny with temperatures peaking around 70s. Winds will be light this morning, but during the afternoon turbulent mixing will result in increasingly gusty north northwest breezes over northern Iowa, with sustained speeds of around 15 MPH and gusts to 25 MPH. Tonight, as the core of the high pressure ridge slides by just to our northeast, winds will turn toward northeasterly and go light again overnight. In our southern and western counties a bit farther from the high winds will stay slightly more organized and some lingering clouds may mitigate radiational cooling, but temperatures there will still likely fall into the low to mid-40s. However, in our northeastern counties skies are more likely to clear and winds may go calm closer to the ridge axis, with temperatures falling into the 30s and possibly even reach freezing levels in a few spots. If confidence in this outcome increases further today, then a frost or freeze headline may become warranted for parts of northern and eastern Iowa early Monday morning.

On Monday the broadly cyclonic steering flow that has been in place over Iowa since late last week will finally begin to move off to the east, but right on its heels a rather energetic shortwave trough will overtop the Rockies along the U.S./Canada border, then on Monday night will dive southeastward into North Dakota and Minnesota. Ahead of this feature, during the day on Monday brief ridging will move over the Midwest and allow for warmer temperatures and winds turning back around toward south late in the day. The southerly breezes will then increase Monday night ahead of the approaching shortwave trough, keeping temperatures warm overnight with lows only in the 50s. As the shortwave nears the Iowa/Minnesota border early Tuesday morning, it will push a trailing surface boundary southeastward into the region. Around or shortly before sunrise Tuesday, increasing warm air and moisture advection ahead of this boundary should be sufficient to generate some showers and perhaps a few thunderstorms over northern Iowa.

The boundary will progress through the remainder of our forecast area during the day Tuesday, though the exact timing is still variable in deterministic model solutions. Temperatures will warm nicely across the area on Tuesday, reaching the lower to perhaps mid-80s in central and southern Iowa ahead of the boundary, and even upper 70s behind it in the north as cold air advection is negligible. Diurnal destabilization leads to thunderstorm concerns along the boundary during the day, however, there are several mitigating factors to consider. One is that the best upper-level support will be translating northeast and east of our area. Another is that some forecast soundings indicate a decent EML inversion that will need to be eroded. Finally, if the boundary passes through our area during the morning and early afternoon hours then it will be less likely to realize maximum destabilization to overcome the inversion. All in all there is certainly some potential for convection and rain in our area on Tuesday, however, PoPs are still forecast at only 20-30% due to the multiple detracting factors. Aside from these concerns, it will also be quite breezy by Tuesday afternoon behind the boundary, with a deep mixed layer up to near 700 MB and a deep layer of 25-35 KT winds just above the surface. This will be particularly pronounced over our northern counties, where northwesterly winds of around 25 to perhaps 30 MPH are expected, with gusts to near 40 MPH at times. It will also remain very dry, with RH values below 25% Tuesday afternoon, however fire weather concerns will be limited due to the greenness of most surface fuels.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1220 PM CDT Sat May 9 2026

VFR conditions prevail through the period. Light showers/sprinkles are passing through the area today, but should produce minimal impacts. Northwest to northerly winds continue this afternoon, sustained around 15 kts with gusts over 25 kts possible at times. Winds will become light and somewhat variable tonight, although the prevailing direction will be out of the north.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 625 AM CDT Sun May 10 2026

VFR conditions are anticipated through the TAF period, with no aviation weather impacts.

DMX WATCHES/WARNINGS/ADVISORIES

None.