textproduct: Des Moines

KEY MESSAGES

- Light snow will fall this afternoon and evening, with a slight chance (20%) of freezing rain briefly in the evening. Snow amounts of 1-2 inches are forecast in northeast Iowa, with less than an inch expected farther southwest. Any icing will be minimal.

- Significantly warmer weather is forecast at the end of this week, especially Friday and Saturday when highs will soar into the 70s and possibly even lower 80s across much of central, southern, and western Iowa.

SHORT TERM /THROUGH TONIGHT/

Issued at 130 PM CDT Tue Mar 17 2026

As has been well-advertised, an area of light to occasionally moderate snowfall is approaching our forecast area from the northwest and west this afternoon. It is being forced primarily by isentropic lift around the 280K-290K surfaces, along with substantially increased moisture aloft. Initially it will need to overcome low-levrel dry air in place with surface dewpoints in the single digits, but upstream observations have indicated this is not positing as much of a detriment as previously anticipated, so precipitation onset times may be a bit faster than thought. Observed visibility via ASOS/AWOS has generally been in the 1-3SM range upstream, but with pockets below 1SM, which in conjunction with thermal profiles supports relatively brief periods of dendritic snow generation and likely measurable snowfall amounts. That being said, with available moisture being limited and the system being transient (accumulating snowfall likely lasting only 3-5 hours in most areas), total snow amounts are still expected in the 1-2" range in our northeastern counties and less in our central and southwestern counties. Unfortunately the timing of the snowfall will impact the afternoon/evening commute, mainly from around I-35 westward.

Of note is that there is a secondary surge of isentropic lift and associated forcing this evening, and several CAMs have been generating associated light showers behind the main snow swath. This signal has only been sporadic, but if such showers do occur then they may prolong the expected minor impacts. In addition, toward the end of the event forecast soundings indicate ice introduction may be lost, leading to the possibility of light freezing rain in any such showers. Even if this occurs any such freezing rain would be localized, light, and of short duration, so any accumulation would be very light and also coming on top of light snow accumulations, mitigating impacts.

LONG TERM /WEDNESDAY THROUGH TUESDAY/

Issued at 130 PM CDT Tue Mar 17 2026

The forecast remains generally dry from Wednesday onward. There are some outside chances at very light and non- impactful precipitation during this period, most notably around Wednesday night when a weak system moves by to our northeast (across Minnesota/Wisconsin) and may be able to generate some sprinkles or drizzle in our service area, mainly the northeastern counties. The current forecast keeps temperatures just above freezing Wednesday night, so not only are precipitation chances low (<20%), but any that did fall would have no discernible impact.

The big story of the long term forecast period will be the return of unseasonable warmth, mainly between Thursday and Saturday. This will primarily be driven by the gradual building of a large heat/high pressure dome over the southwestern U.S., which will increasingly exert its influence up over the Midwest and Iowa. On Thursday its influence will be muted by a surface high pressure area sliding across Iowa, but even so skies should remain mostly sunny at least across the southwest half or so of our forecast area, and forecast high temperatures are in the 60s in that area. By Friday morning surface flow will be back around to southwest and deeper mixing will support even more pronounced warming. Most model solutions now bring a weak surface trough through the area Friday afternoon with winds turning to northwesterly, but even then there is a lack of cold air advection behind the trough initially, and in fact it may subtly enhance low-level turbulent mixing supporting warmer temperatures behind the trough. Have bumped the high temperatures for Friday back up just a bit accordingly, close to the levels we advertised the last couple of days with highs in the 60s northeast to near 80 southwest. A similar set-up is then in store for Saturday, with the low-level wind forecast being less certain but very warm temperatures aloft and an expectation of limited cloud cover supporting a third unseasonably warm day in a row.

Another surface trough/cool front will come through around Saturday night, likely with more (but still modest) cold air advection than the one(s) preceding it, and also with a chance of precipitation but still <20% due to limited moisture and upper-level support. Of greater note is that this will bring a temporary end to the warmth, but even behind the front temperatures will only be slightly below normal, with highs next Monday still in the 40s to lower 50s.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1044 PM CDT Tue Mar 17 2026

Light snow, freezing drizzle/mist, and MVFR stratus will departing the area through the early morning hours, giving way to VFR conditions through the day Wednesday. Breezy southerly winds tonight will become light and somewhat variable through Wednesday, with prevailing direction generally out of the west to southwest.

DMX WATCHES/WARNINGS/ADVISORIES

None.