textproduct: Des Moines

KEY MESSAGES

- Breezy winds increasing tonight into Tuesday. Sustained winds nearing 30 mph and gusts up to 40 mph could lead to erratic fire behavior, as well as blowing dust in rural areas.

- Scattered showers late tonight into mid-day Tuesday. A few rumbles of thunder are possible south Tuesday afternoon. A few gusty winds are possible but severe weather risk looks low.

- Warm temperatures expected through the week, with widespread shower and storms returning late Thursday into Friday.

SHORT TERM /THROUGH WEDNESDAY/

Issued at 251 PM CDT Mon May 11 2026

It's been yet another day pleasant day across Iowa, as clear skies complement the light winds beneath surface high pressure today. Temperatures have warmed nicely just through insolation from the May sun, putting temperatures in the mid 60s northeast to mid 70s southwest. Farther south and west of the area, south southwesterly winds have started to advect warmer air up into eastern Nebraska and southeastern Iowa, leading to even warmer temperatures in the upper 70s to low 80s. As the surface high moves off later today and into tonight, this warm air advection will begin to work it's way into Iowa, keeping temperatures warmer tonight and increasing into the 80s on Tuesday. This southwesterly return flow is a sign of the upper level wave forecast to dive southeastward across the upper Midwest tonight into Tuesday, dragging a weak boundary through the area on Tuesday.

Surface pressure gradients tonight will respond to the incoming shortwave, boosting winds overnight into Tuesday. While an inversion does set up tonight, the tighter pressure gradients will still allow for breezy sustained winds around 15 to 20 mph overnight with occasional gusts up to 30 mph possible. However, the strongest winds will develop as the boundary layer mixes out and surface boundary passed through during the day on Tuesday. The environment is checking many of the boxes for efficient wind production on Tuesday; a deeply mixed boundary layer, tight pressure gradients, and very dry conditions. Behind the boundary, moderate cold air advection will also help with downward momentum transfer of winds, as well as produce impressively uniform and unidirectional flow throughout the mixed layer. In fact, the RAP and GFS show 30+ kt winds through the entire boundary layer, barring the wind right at the surface, resulting in a layer mean of around 32 kts. In other words, there will be quite a bit of momentum through a deep layer just above the surface, which likely won't be as affected by surface friction as the model may indicate with it's depicted surface winds. Likewise, NBM probabilities indicate a roughly 50 to 60 percent chance of 30 mph or greater winds through Tuesday afternoon, with a one hour bullseye of 70 percent or greater near Estherville. Northern Iowa is where the strongest winds are expected, but similar profiles (albeit to lesser magnitudes) are in place throughout the state. This indicates fairly good confidence in breezy sustained winds on Tuesday afternoon, which will be flirting with wind advisory criteria over northern Iowa. Gusts could approach advisory criteria as well, but the lack of any really strong (40 kt+) winds in the mixed layer implies the top end may not be as high. Therefore, only expecting gusts up to 40 mph based on current guidance.

With the windy, warm and dry conditions Tuesday, there will be some concern for erratic fire behavior, although fuels should be green enough to limit significant concerns for uncontrolled fire spread. Another, less common hazard (for Iowa) tomorrow is the potential for pockets of blowing dust, especially in more open, rural areas. Crops in the fields aren't too far along yet, and soils are loose and likely very dry given conditions from the last few days. Therefore, the sustained winds near or exceeding 30 mph could very well pick up dust from fields and result in pockets of lower visibilities through Tuesday afternoon.

In addition to the winds around this system, we are also still looking at chances for some scattered showers starting north late tonight and dropping south and eastward through Tuesday. The main source of forcing looks to stay to our north and east, meaning the best synoptic ascent will be over northeastern Iowa Tuesday morning. Moisture availability still seems to be the main limiting factor for rain in northern Iowa Tuesday morning. We will have increasing gulf moisture, but the antecedent conditions are very dry and will requires some top down saturation to reach the surface. NBM still isn't overly convinced in rain chances, so have continued to boost precipitation chances in the forecast above NBM guidance, just given the lift through the saturated layer aloft. The upper level wave will track eastward away from the state through the day Tuesday, taking the synoptic support with it, although high resolution guidance continues to produce at least light reflectivity along the boundary/trough. Model soundings show good mid-level saturation, but very dry low levels, suggesting hydrometeors will evaporate before reaching the surface. Lift will also be dependent on weak lift aloft, as the low level convergence along the surface boundary will be fairly weak. With the saturation aloft, can't rule out a few drops squeaking through the dry layer, but confidence is pretty low in measurable precipitation. Therefore, have kept PoP chances around 15 to 20% for areas over central and southern Iowa through mid-day Tuesday. A small stripe of instability does still try to develop in southeastern Iowa, but only amounts to at most 1000 J/kg. Therefore, the threat for severe weather looks low, but can't rule out a rumble of thunder and maybe some gusty winds if any showers/storms overperform.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/

Issued at 251 PM CDT Mon May 11 2026

Milder air fills in behind the boundary Tuesday night into Wednesday, but upper level ridging quickly builds eastward into the state through mid-week. Temperatures will still reach the 70s under the surface high pressure on Wednesday, then into the 80s as southerly flow returns under the thermal ridge on Thursday. The 500 mb ridging will be abbreviated, though, as another 500 mb trough quickly begins to move in on the backside of the ridge late Thursday into Friday. This will open the state back up to a slug of gulf moisture, with broad warm, moist air advecting into the state and bring the return of shower and thunderstorm chances Thursday night into Friday. Instability will be present on Friday afternoon, which could lead to some stronger storms, although wind fields look less impressive at this time range. Will better assess severe threat in the coming days. The pattern looks to remain active and warm through the weekend as well.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1101 PM CDT Mon May 11 2026

VFR conditions to prevail through the period. Overnight gust groups will be sporadic, but sustained winds will be over 10kts. Gusts will be over 30kts at times after 12z with a gradual wind shift to northwest winds after 18z. Gusts will decrease after 00z. Have shortened or removed shower mentions due to decreasing confidence and low impacts.

DMX WATCHES/WARNINGS/ADVISORIES

None.