textproduct: Des Moines

KEY MESSAGES

- Large gradient of high temperatures across the state today, with highs in the 50s north to 80s south.

- Breezy winds with gusts up of 35 to 40 mph possible as cold front passes through today. High to very high fire danger expected with the gusty winds. - Isolated light showers/sprinkles today move through today, with a few thunderstorms possible in southern Iowa this evening. Any stronger storms could produce hail. - Dry and mild conditions develop Friday and Saturday, with occasionally breezy winds both days. Increased fire danger likely both days, but especially Saturday.

SHORT TERM /THROUGH TONIGHT/

Issued at 346 AM CDT Thu Mar 26 2026

Satellite imagery depicts increasing cloud cover from our northwest and KDMX is picking up light radar returns over southern Minnesota, indicating the approach of our much discussed low pressure and cold front today. Farther south, surface observations are showing a surge of 50+ degree dewpoints into northern Missouri and southern Iowa as warm, moist air is advected northward toward the state. Through the day, the elongated surface low pressure will drop south and east through the state, trailed by a cool, dry air mass, serving as our main driver for weather conditions in Iowa today.

The most widely observed impact from this system's passage today will be breezy winds. Tightened pressure gradients both at the surface and aloft will drive up wind speeds ahead and behind the front, starting out of the southwest ahead and then flipping to northerly behind. While it will be breezy everywhere, the strongest winds will move through with the cold air advection and height rises following the front. North winds of 20 to 25 mph are likely, with gusts of 35 to 40 mph possible at times. With the front already knocking on the doorstep of far northwest Iowa, expectation is for the boundary to be entering the northern portions of our forecast area around 6 to 7 am, through the I-80 corridor by around 12 pm to 1 pm, then through the entire area as soon as 4 to 5 pm. In addition to the winds, the arrival of the cold, northerly flow will dictate how warm temperatures get today. Southern Iowa will be the warmest, as it will spend the most time within the warm air, while northern Iowa will be coolest with the front already moving in around sunrise. This results in a 30 degree difference from the high of 55F forecast for Estherville to the high of 85F forecast for Centerville.

With the breezy winds today, elevated fire weather concerns remain on the the table today, both with the warm, moist air mass ahead of the front and the cooler, but drier air mass behind the front. Despite the 50 dewpoints expected in southern Iowa, relative humidities are still expected to fall into the 35 to 45 percent range this afternoon thanks to the unseasonably warm temperatures. That said, winds won't be as windy in the warm sector as behind the front. In the cooler air behind the front, both temperatures and dewpoints will be lower, keeping relative humidities generally a bit more moist in the 45 to 55 percent range. However, stronger winds behind the front and dry fuels will still lend to erratic fire behavior even with the cooler air. The net result is high to very high fire danger values from the Grassland Fire Danger Index (GFDI) across Iowa today, with the highest values favoring western into central Iowa where winds will be strongest and humidities the lowest. Burning is discouraged today, as fire starts and spread will be more likely under these conditions.

Finally, some low end precipitation chances (15 to 25%) will drop southward through the area with the boundary today, much of which appears to be post frontal. Soundings and cross sections both indicate an elevated mixed layer will likely evaporate most hydrometeors that develop within the saturated layer above it, keeping most of Iowa dry today. However, weak instability aloft and respectable lift in this layer does imply that there could be some top-down saturation of this layer, especially as these showers work their way south and east into the state where soundings indicate the EML will be a bit weaker. The net result at the surface will likely be a few sprinkles or a brief light shower for most impacted by precipitation during the day.

In addition to the light shower/sprinkle potential north and central, the possibility for thunder will increase the farther south and east the front gets. This will range from a rumble or two of thunder being possible in south central Iowa this afternoon, to potentially even a stronger storm in the far southeastern reaches of the forecast area this evening. Similar to the showers, it appears that any thunderstorm activity will likely be post frontal, as even forcing along the surface front will struggle to overcome the warm nose and ~200 J/kg of convective inhibition ahead of it. That said, 1000 to 1500 J/kg of MUCAPE and more saturated mid-levels will favor a few elevated storms in the early evening hours behind the initial front. The effective shear in the layer won't be overly high (20 to 30kts), and would be fairly unidirectional, but it's certainly possible we could see some hail in far southeastern Iowa this evening. With the storms being elevated and low and mid-levels more saturated, downdraft CAPE values are low (~200 J/kg or less) suggesting damaging wind is unlikely. Likewise, storms being post frontal eliminates the threat for tornadoes. Therefore, if storms do go, hail and lightning will be the primary concern.

LONG TERM /FRIDAY THROUGH WEDNESDAY/

Issued at 353 AM CDT Thu Mar 26 2026

Widespread north/northwesterly flow remains Friday following the departing front to the south/east, with a large area of high pressure descending across the region. Much cooler and drier conditions are expected for the day, with forecast highs in the low 40s north to low 50s south. The aforementioned surface high is slated to slowly depart the region through Saturday, with a return to mid-level ridging across the western CONUS once again. At the low levels, this means another warming trend on the horizon, as warm air advection pushes warmer air back into the state into early next week as forecast highs are expected to top out through the 70s. Dry conditions on both Friday and Saturday may result in high to very high fire danger as relative humidities drop into the 20 to 30 percents both days. This is especially true on Saturday, as warmer temperatures and breezy conditions push RHs to critical levels. Evaluation of potentially critical fire weather conditions on Saturday will be needed in the coming days.

The signal remains for the overall pattern to turn more active moving into the beginning of April as long range guidance depicts at least a few defined troughs ejecting into the Central Plains. Something to continue monitoring over the coming days.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 625 AM CDT Thu Mar 26 2026

Sprinkles and light showers are drifting over northern Iowa this morning, although conditions have primarily remained VFR. There are a few observations of a light mist, which could lead to brief MVFR vsby reductions, but confidence is too low to include this in any given site at this time. These light showers will continue south and east through the day, with KALO and KOTM most likely to be impacted. A few thunderstorms are also possible in southern Iowa near KOTM this evening.

In addition to precipitation, a cold front dropping through northern Iowa will flip winds from southeasterly to northerly through the day. Breezy winds will accompany this front, with gusts of 30 to 35 kts possible at times. The strongest winds will be behind the windshift but breezy winds are expected prior to it as well. Winds remain breezy into the evening, with a slight lull tomorrow morning before picking up again on Friday.

DMX WATCHES/WARNINGS/ADVISORIES

None.