textproduct: Des Moines

KEY MESSAGES

- Drizzle or light rain is likely across northern Iowa tonight into early Tuesday. Temperatures will hover near freezing, and if they fall just below then very light icing may occur on some surfaces and impact travel in those areas.

- Becoming milder this week with several rounds of precipitation, mainly in the form of rain accompanied by thunderstorm chances Wednesday and especially Friday.

UPDATE

Issued at 244 AM CST Mon Mar 2 2026

The dry air won out in southern Iowa overnight, where no precipitation has been observed and radar imagery now shows no echoes. Even if some drizzle does still occur there in the next several hours, ground/road temperatures remain above freezing beneath thickening clouds so no icing would be anticipated. Have removed POPs/weather from the forecast this morning accordingly.

A very expansive low cloud field across Missouri, Kansas, and surrounding states has surged northward into Iowa overnight, with the northern edge now past Highway 30 and on its way toward the Minnesota border later this morning. Given the size of the upstream cloud field and persistent east southeast low-level flow today, it is not surprising that the majority of short- range model solutions sock in our area right through today and tonight, and have updated the forecast to indicate cloudy skies right into Tuesday. With this persistent low cloud cover anticipated, also nudged temperatures down today and up tonight, albeit only by a degree or so.

The bottom 5-8 KFT of the atmosphere will gradually saturate today and especially tonight, with at least patchy drizzle occurring at times mainly after sunset. Meanwhile, there is unanimous agreement among model solutions in a ribbon of frontogenetical forcing associated with a mid-level impulse moving eastward from South Dakota late today along the Iowa/Minnesota border region tonight into early Tuesday. This supports a higher expectation of precipitation in our northern counties overnight, and have increased POPs to near 60 percent though there is some question as to how widespread measurable precipitation (i.e., greater than a Trace) will be. It does appear likely that a good portion of our north will see 0.01"-0.03" tonight into early Tuesday. Temperatures will be close to freezing during that time and there is some potential for freezing drizzle and light icing which could impact travel in northern Iowa. However, at this time it appears slightly more likely that the low clouds and persistent (if light) east southeasterly breezes will keep surface wet-bulb temperatures right at or just above freezing (60% confidence) versus below freezing (40% confidence). This will bear watching as we update the forecast today and tonight.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 239 PM CST Sun Mar 1 2026

Satellite imagery this afternoon shows broken cloud cover over much of Iowa as mid-level moisture streams overhead. A look at the radar sampling across Iowa indicates light returns over the northern half of Iowa, and some southern portions as well. Surface observations however indicate only dry conditions across the forecast area, which is thanks to the large area of 1036mb high pressure centered over northern Minnesota/Ontario that is pushing dry air in the low levels across the region, eating up any snowflakes that are produced before reaching near the surface. The feature responsible for the light returns is the midlevel shortwave and stronger forcing for ascent that is located over Missouri, with the northern fringe of the associated precipitation shield into Iowa. The influence of dry air from the surface high will remain across the state, even now trending all the way down to the IA/MO border, where any remaining snow amounts from previous forecasts how now been removed. However, have kept as least low chances (20-30%) of light snow showers in the southern two tiers of counties to account for at least some potential for flakes to reach the surface, but accumulations are unlikely. Much of the forcing departs eastward with the shortwave late tonight into Monday morning, though there does remain some potential for lingering precipitation over far southern Iowa to switch over to freezing drizzle as the mid-levels dry out (loss of ice introduction), with saturation trying to hold on in the low levels. A closer look at soundings shows some rather weak lift in the saturated area, though closest to the surface remains at least a shallow dry layer that overall lessens confidence on seeing freezing drizzle reach the ground. Probabilistic ensemble guidance also has trended down chances of 0.01 inch of ice to around 10-15% over south/southwest Iowa, with increasing chances further south and west into Nebraska/Missouri. Therefore, have lowered PoPs during into Monday morning and removed any ice accumulations out of southern Iowa, though have left at least some mentions in the forecast if better saturation to the surface ends up occurring. Those in southern Iowa should remain in tune with the forecast in case any notable changes occur, but should plan on at least some potential of isolated slick conditions if freezing drizzle does develop through the Monday morning commute.

Conditions are expected to dry out across the forecast area by the afternoon, though remaining cloudy but warmer given a switch to southeasterly flow, as highs are expected to reach into the upper 30s through the 40s, warmest south. Model guidance depicts a longwave trough over the Desert Southwest, which is projected to gradually move eastward into the Central Plains into midweek. Ahead of this though, a piece of mid-level energy breaks away from this larger feature, arriving over northwestern/northern Iowa Monday evening. This looks to bring the potential for precipitation over northern to central Iowa Monday night into early Tuesday morning. This light precipitation is expected to be mainly in liquid form as the temperatures are expected in the mid to upper 30s, thanks to warmer surface flow out of the southeast. Weaker forcing along with the lack of mid-level moisture though would suggest drizzle to very light rain, but cannot rule out temps right around freezing in northern Iowa that could support some freezing drizzle at times. Further south, another feature in the form of a subtle warm air advection wing of forcing lifting northward through Missouri through the morning arrives into Iowa, bringing additional and more scattered light drizzle to rain shower activity across Iowa.

By Tuesday evening to Wednesday morning, the mid-level trough and closed low pressure system mentioned above arrives somewhere over the western Central Plains (some minor differences exist between models), with a surface low pressure system lifting northeast into portions of Iowa/Missouri/Illinois. A frontal boundary lifting northward from Missouri during this time per NAM/GFS guidance lifts through Iowa, which comes with better forcing and overall dynamics that could support more noteworthy rainfall and even the chance for thunderstorms. Instability into Iowa looks generally low-end at this time around 50-100 J/kg over the south/southeast, though bulk shear in the same area is quite impressive, pushing over 40-50 knots. Cannot rule out at least some elevated storms with this activity Wednesday morning, so will be monitoring this over the coming days. SPC has placed a General Thunder outlook that covers a larger area through the southern two thirds of Iowa, which will likely become more focused over the next few days.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 239 PM CST Sun Mar 1 2026

Later Wednesday and beyond looks to remain on the more active side, with periodic chances for showers and even more widespread thunderstorm potential by Friday. Long range guidance later Thursday shows surface cyclogenesis that forms a rather strong surface low pressure system, which per guidance passes northeast into Iowa through Friday. At this time, the state should be in the warm sector, with notable moisture return as dewpoints increase into the 40s to 50s and temperatures in the 50s to 60s. A look at instability overhead is quite notable, with values around 500-1000 J/kg, highest over southern Iowa. Certainly a favorable setup to watch closely over the coming days for storms, but to say if any severe weather is possible is a bit early this far out.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1140 AM CST Mon Mar 2 2026

Widespread MVFR conditions to begin the period over Iowa though KDSM is the exception at VFR. Expect cigs to rise this afternoon into the 2500-3500 ft range before cigs descend tonight and into Tuesday morning. Cigs will become IFR to LIFR late in the forecast period. Areas of drizzle may develop as well with a period of freezing drizzle possible near KMCW. The wind will be from the southeast with a few sites near 12 kts sustained this afternoon before diminishing.

DMX WATCHES/WARNINGS/ADVISORIES

None.