textproduct: Des Moines

KEY MESSAGES

- Very low chance for precipitation in the west and northwest (<15%) on Friday afternoon.

- Temperatures moderating to above normal by Sunday into next week with mainly dry conditions.

UPDATE

Issued at 236 AM CST Thu Jan 1 2026

Main change in the short term is the evolution of a cluster of shortwaves moving off the Rockies on Friday. The RAP and NAM eject one of these features towards northwest Iowa Friday afternoon. 850mb flow takes a southwest component in these runs, which in turn introduces a melting layer to northwest Iowa, yielding freezing rain. Confidence in this solution is low (<15%) as the overall upper air pattern favors a southeast dive of synoptic features. This is seen better by the GFS and ECMWF as they focus the subtle features along the northwest flow and into a southern stream trek. Will continue to monitor trends today. For now, deviated from the near 0% NBM output, putting around a 7-12% chance of precipitation chance in the west.

DISCUSSION

Issued at 137 PM CST Wed Dec 31 2025

Upper level GOES-East water vapor imagery shows a ridge over the western CONUS with a closed low off of the California coast that will slowly move eastward through the end of this week. There is a plume of moisture flowing over top of this ridge and into our region in the fast, 130 knot 250mb northwesterly flow. A shortwave trough can easily be seen in this imagery and is just northeast of Lake Superior. A surface cold front is trailing back to its west and is the feature of interest for our potential light wintry precipitation over our northeastern forecast area from around Mason City to Waterloo this afternoon into early this evening. However, there are several forecast parameters that are marginal and bring into question whether it will occur. First, the ice introduction layer may or may not have saturate, depending on the model, though it can be stated with confidence that there is a gradient in ice introduction/drier air over the same Mason City to Waterloo area. If ice introduction is achieved, then flurries or light snow would result, which seems to fit with current surface observations, mPINGs, and reported road conditions in Minnesota. If there is no ice introduction, then freezing drizzle may result. Forecast soundings show that saturation is elevated above the surface and around a 1km in depth for a few hours at most. While low and mid- level thermodynamics and upper level kinematics are favorable for lift, the saturated layer shows a lack of lift with neutral to weak subsidence in forecast soundings. Lastly, there is some degree of wind shear, but that becomes more unidirectional as the boundary moves through the area. Therefore, have trimmed back areal extent of freezing drizzle mentioned in the forecast with updates this morning and have maintained that thinking and forecast into this afternoon. Any icing, if it were to occur, would be a hundreth or two as drier air pushes in and dries out the column.

As the cold front clears the state tonight, temperatures will fall into the single digits and teens above zero by New Year's Day morning. Another subtle, fast moving shortwave will slip into and through the region on Thursday, but the moisture profiles are insufficient with lots of dry air in the mid-levels for any snow over our forecast area. The jet stream and shortwave trough train will trek a bit farther northeast through the first weekend of 2026, though the aforementioned closed low off the California coast will slide across into the central or southern Plains. Moisture return this far north looks unlikely so not expecting any significant precipitation through the weekend as temperatures moderate to normal by Saturday and above normal by Sunday. The West Coast ridge axis pushes over the central US early next week while at the same time deamplifying, which may allow the jet stream to bring light precipitation chances closer to the northern border of the state. As the the flow becomes more southwesterly late in the week, this presents a more opportune setup for precipitation and something to watch in the coming days.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 530 AM CST Thu Jan 1 2026

Trends this issuance favor the MVFR stratus deck returning over all sites at some point after 17z, likely not vacating from the lack of winds for the remainder of the period.

DMX WATCHES/WARNINGS/ADVISORIES

None.