textproduct: Des Moines

KEY MESSAGES

- Unseasonably warm temperatures develop across the area today

- Cold front passage on Thursday brings breezy conditions and large high temperature gradient over the state. Elevated fire weather concerns due to gusty winds.

- Few showers possible (20 to 40%) behind the cold front on Thursday. Isolated thunderstorm possible in southern Iowa, but greatest storm risk is outside our area.

- A cooldown is expected Friday, then gradually warming through the weekend into early next week, while remaining generally dry.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 334 AM CDT Wed Mar 25 2026

>> UNSEASONABLY WARM TODAY

Unseasonably warm conditions develop today as the broad 500 mb ridge builds eastward into Iowa, keeping the state in a northwest flow pattern aloft. Lower down in the atmosphere, an 850 mb trough and building surface low pressure will help to advect warmer temperatures from beneath this ridge into the state, boosting highs today into the 70s to near 80 in southwestern Iowa. Patchy mid and upper level cloudiness sourcing from the pacific moisture stream will filter sunshine through the day, so the duration of cloud cover at any given location will likely play a role in how the temperature forecast plays out. If clouds are less expansive and clouds clear out, today could be a prime day for overachieving temperatures thanks to the warm mid-level temperatures and mixing that would come with more sunshine. Higher dewpoint air will also be streaming into the state today, helping to negate relative humidities completely dropping out with the warmer temperatures. RH values drop into the 30 to 40 percent range this afternoon with light to occasionally breezy winds, especially in southern Iowa where gusts over 20 mph are possible at times. These moderately dry conditions and breezy winds could allow fires to spread quickly today, leading to some elevated fire weather concerns mainly over southern Iowa.

>> BREEZY ON THURSDAY WITH ELEVATED FIRE DANGER

Warm conditions look to continue for at least parts of the state on Thursday, but our mid-week warmup will be coming to an end as the ridging to our west breaks down and troughing over Canada pushes a cooler air mass down into the central US. On the periphery of this cooler air will be an elongated area of low pressure, which will first pull warm, moist air up into Iowa ahead of the cold front passage. The cold front will then drop southward through the daytime hours, arriving in northwest Iowa around mid-morning, bisecting the state from southwest to northeast by around 12pm to 1pm and then fully through the area just before sunset around 6 pm. Thanks to this front, there will be a healthy gradient of temperatures over Iowa on Thursday, with highs reaching the mid to upper 50s to 60s north and the upper 70s to low 80s south. Of course, depending on a faster or slower progression of the front, high temperatures could fluctuate.

Increased pressure gradients around this system both at the surface and aloft will lead to windier conditions on Thursday. This will be especially true behind the cold front, where strong cold air advection and pressure rises will aid in the downward momentum transport of 30 to 40 kt winds aloft. Northerly winds of 20 to 25 mph are likely on Thursday, with gusts up to 40 mph possible. Breezy winds will introduce some additional fire weather concerns on Thursday, although with cloudy skies and falling temperatures, RHs only fall to around 40 percent for most of the state. Therefore, while fires may behave erratically on Thursday and elevated fire danger is expected, critical fire weather concerns aren't anticipated. Of course, any precipitation that occurs would negate any fire weather concerns.

>> SHOWER AND THUNDERSTORM POTENTIAL THURSDAY

In addition to winds, temperatures and potential fire weather concerns, model guidance continues to produce token precipitation chances as the front passes through the state. These are mostly post-frontal, and source from mid- and upper- level saturation. However, model soundings and cross sections show a fairly healthy mid-level dry layer that never fully saturates down to the surface, despite 20+ microbars of lift occurring above it. This dry layer will put a hindrance on any appreciable precipitation reaching the surface, but given the healthy lift and pockets of weak instability (< 100 J/kg), would not be surprised to see a shower or two produce enough hydrometeors to saturate down through this layer. Saturation will most likely be achieved as the showers have persisted, meaning the southern and eastern portions of the state will be most favorable for rainfall. Given all this, have pulled back on the 50+ percent precipitation chances that NBM was forecasting, but maintained at least some low end precipitation chances (15 to 25 percent) through the day Thursday, with slightly higher chances (35 to 45 percent) favoring central into southern Iowa.

Finally, there does remain at least an off chance for a thunderstorm over the far southeastern portion of our forecast area late Thursday afternoon and evening. This will be where instability is maximized for our forecast area, with some models progging 1000+ J/kg of MUCAPE and plenty of shear in the layer for a more organized updraft (albeit unidirectional). That said, the mid-level warm nose appears to keep our area mostly capped off through the day which would either need to mix out or be overcome by the cold front. Despite the environmental conditions in place, most of the high resolution guidance isn't indicating much for convective initiation until the front is out of our area, likely due to this warm nose. Therefore, the risk for storms seems fairly conditional for our area. If a storm were to develop before the cold front pushes through, hail and gusty winds would likely be our primary concerns. The storm prediction center does have a very small portion of our area in the marginal risk (level 1 of 5) for severe weather, but this again would be contingent on storms being able to overcome the warm nose.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 235 PM CDT Tue Mar 24 2026

By Friday, a substantial cooldown is expected to occur as cold air advection covers the state, with a rather large area of Canadian surface high pressure tracking into the region. Highs are expected to be about 20-25 degrees cooler with values only in the mid to upper 40s north and in the low 50s south. Though cooler, winds remaining breezy and very dry air resulting in RHs to drop into the 20s to 30s will lead to additional fire weather conditions, especially over central to southern Iowa.

A look over the western CONUS though shows mid-level ridging building once again, suggesting the gradual return of warmer conditions into early next week. Dry conditions are expected to remain into the weekend as this high pressure slowly descends southeastward across the region, departing into Sunday. There is a weak signal for light rain Sunday in the long term guidance, driven by very subtle features in the larger-scale flow, but the lack of moisture and overall forcing is not enough to really increase confidence to include precipitation chances in the forecast at this point, so have left out. Temperatures peak Monday as the warm air arrives overhead, with highs back through the 70s.

By Tuesday into midweek, the pattern does look to turn more active as a few larger troughs eject into the region in terms of potential for showers and even some storms, so something to watch over the next several days.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 619 AM CDT Wed Mar 25 2026

Primarily VFR conditions will prevail through the period as mid- and high clouds drift through the area today. A few hours of LLWS are expected this morning, then diminishes as winds pick up. Winds today will be light to occasionally breezy out of the south. Winds then go light and variable overnight.

DMX WATCHES/WARNINGS/ADVISORIES

None.