textproduct: Des Moines

KEY MESSAGES

- Increasing winds tonight may cause snow on the ground to blow and drift in rural areas, mainly over northern Iowa.

- Milder and dry for the first half of the week. Melting of the snowpack to varying degrees will result in refreeze of melting snow on surfaces. Will need to monitor for possible fog formation.

- Next chance for precipitation late Wednesday into Thursday. Gusty winds possible on Thursday.

DISCUSSION

Issued at 159 PM CST Sun Dec 14 2025

Upper level pattern this afternoon shows a trough pushing into and through the Great Lakes region with Iowa on the backside of the trough and ridging over the western US. In the low levels (850/925mb), warm air advection is ongoing over Kansas and Nebraska and just starting to push over western Iowa. This will continue through tonight as southerly and then southwesterly winds increase allowing for temperatures to rise overnight. While there is an inversion given the lingering surface Arctic air with WAA aloft, winds around 1000 feet are at 35 to 45 knots. While this is not a favored setup for efficient momentum transport of the gusts to the surface, did increase winds from the initial National Blend of Models. This pushes sustained winds to 15 to 25 mph over much of the forecast area with the highest winds and gusts over 25 to 35 mph over northern Iowa and along the Highway 71 corridor. Cooperative observer reports of 4 or more inches of snow on the ground this morning combined with these winds can result in patchy blowing snow in open rural areas tonight into shortly after sunrise Monday.

With the jet stream displaced to the north of the state, the first part of this week will feature milder and dry conditions. The milder conditions will result in melting of some or all of the snowpack depending on the snow depth on the ground. With higher above 32 degree wet bulb temperatures Tuesday and Wednesday, especially over the southwestern half of the state, these days look more prime for melting. This, of course, will bring concerns for refreeze as the sun sets each night on area surfaces. In addition, fog development may be possible with near surface moisture in abundance if winds and sky conditions align favorably. Beyond the melting snow and fog potential, a shortwave trough will trek along the US and Canadian border Tuesday that will result in an overall increase in cloudiness over Iowa, but soundings continue to show too much dry air for any precipitation. The more impactful system looks to arrive Wednesday into Thursday as an amplified shortwave trough travels from the Pacific Northwest to around Minnesota. With the associated surface low pressure staying north of Iowa as well, this will keep the state in the warm sector with more than sufficient low level thermodynamic and upper level kinematic forcing for precipitation. Thus, expectation is for precipitation type to favor rain at least initially, though some snow may mix in as colder air wraps in behind the cold front and departing low. A period of strong and gusty winds is also expected on Thursday with gusts over 35 mph possible in at least some portions of Iowa dependent on storm track and strength. Temperatures do lower with lows Friday morning back to around zero degrees over northern Iowa and highs knocked back to near seasonal levels for mid-December.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1101 AM CST Sun Dec 14 2025

While there is high confidence in VFR conditions prevailing through the period at the terminals, a period of low level wind shear is forecast to develop tonight into Monday morning. This will be due to increasing surface winds from the south and low level winds from the southwest. Patchy ground blowing snow is possible over parts of northern Iowa tonight due to the increasing winds, but not included at any terminal given limited spatial extent.

DMX WATCHES/WARNINGS/ADVISORIES

None.