textproduct: Des Moines

KEY MESSAGES

- Brisk, gusty winds from the northwest and cool today.

- Milder on Sunday with a bit less wind and mostly sunny.

- Off and on precipitation chances with dry periods the first half of the week as conditions trend from cool to warm.

- A wet pattern late in the week into next weekend with intervals of rain and storms. Will need to monitor trends as signal is present for possible flooding in the region, if not possibly somewhere in the state.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 332 AM CDT Sat Apr 4 2026

Storm activity has shifted eastward out of the state as surface low pressure over northeastern Iowa exits into Wisconsin this morning. In its wake, there is plenty of cloud cover behind the low and winds are becoming from the northwest. These winds will increase into the daylight hours as modest cold air advection (CAA) prevails and steepens low level lapse rates. These steeper lapse rates will aid in momentum transport with top of mixed layer winds near 40 knots. We may not realize the full potential of wind gusts given that the CAA wanes into the afternoon and there is a lack of a strong pressure rise couplet. It will be a windy day nonetheless with sustained winds from the northwest at 15 to 25 mph with gusts of 30 to 40 mph common. Forecast soundings also show elevated instability building up to around 50 J/kg, which will aid in spotty rain and snow shower development by late this morning into early this evening, particularly and mainly north of Highway 30 over northern Iowa, as the moisture continues to wrap around the departing low pressure. While no accumulation is expected, brief visibility reductions to around a mile are possible as a shower passes any given location. Highs will be a bit below seasonal values near 40 degrees at the Minnesota border to near 50 degrees at the Missouri border.

High pressure will drop into the central Plains on Sunday with milder conditions as high temperatures will be about 10 degrees higher than Saturday. Wind will not be as strong as Saturday, but will still average between 10 and 20 mph with gusts up to 30 mph under a mostly sunny sky. As the high slips away, a baroclinic zone will set up over Nebraska into western Iowa with low level thermal lift and QG convergence trying to spur on light precipitation. However, moisture availability will be limited and from the source region of the Pacific with forecast soundings show that achieving moisture saturation may be a challenge.

LONG TERM /TUESDAY THROUGH FRIDAY/

Issued at 332 AM CDT Sat Apr 4 2026

Stronger low level flow and theta-e advection is forecast on Tuesday as high pressure moves over the Great Lakes and surface low pressure moves east of the southern Canadian Rockies. This low will aid in transporting Pacific moisture across the region. Off and on precipitation chances are likely Tuesday into Wednesday within the thermal lift regime. As the Canadian low moves into the Quebec province, the cold front will lose its drive somewhere just south of Iowa late in the week. As this stalls out, pulses of shortwave energy and surges of theta-e advection will invigorate rainfall and storm chances from Thursday into next weekend over the region. Many, though not all (e.g. 0z ECMWF), deterministic, ensemble, and AI solutions continue to point to 1.5 to 3 inches of rainfall in some part of the state in this period, which raises concerns for river flooding and flash flooding. Of course, it will all depend on where the front ends up as to where the rain falls, which will play a big role in these concerns. Rivers are currently responding to the rainfall of the past few days with these likely to not return to their pre- rainfall levels, or base flows. Thus, in channel capacity is reduced. Soils will, to some degree dry, in the coming days, but are likely to have some level of reduced capacity as well compared to the first part of this past week. National Water Model forced by the GFS and NBM are showing high annual exceedance probabilities (AEPs), which correlate to mainly within bank rises or perhaps minor flooding, on larger stream segments late next week and weekend. This is also shown in the experimental 10 day Hydrologic Ensemble Forecasting Service (HEFS) with 30% chance of exceedance showing several forecast points having within bank rises and 10% chance of exceedance showing about a half dozen forecast points breaching minor flood stage.

As for severe weather potential late next week and weekend, it looks low with meager amounts of instability and deep layer shear, which is also reflected in the AI/ML guidance largely. While we will be watching how this evolves, the hydrology and flooding side has more concern than the severe potential at this point.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 632 AM CDT Sat Apr 4 2026

A mix of MVFR, IFR, and LIFR ceilings are in place across the state this morning. Ceilings are expected to rise through the day on Saturday, eventually achieving VFR heights at all sites except KMCW by afternoon. However, scattered rain or snow showers are expected across the northern part of the state in the afternoon. Their impact on cloud cover is expected to stay scattered, and therefore not modify the flight category, but this will be monitored for a possible change to BKN in future updates. It is also uncertain whether these showers may impact any TAF sites as they will be isolated in nature, but a PROB30 may be needed in the next update. Lastly, winds will be gusty from the NW at all sites during the afternoon and early evening, reaching at least 25-30 knots.

DMX WATCHES/WARNINGS/ADVISORIES

None.