textproduct: Des Moines

KEY MESSAGES

- While nothing compared to yesterday, it will turn breezy this afternoon and a bit less so on Saturday.

- Above normal temperatures next week and favoring a mostly dry forecast.

- Will need to monitor for possible fog development over areas that have snowpack, which will melt over the next week.

DISCUSSION

Issued at 330 AM CST Fri Dec 19 2025

GOES-East upper level water vapor imagery shows the trough moving through the Great Lakes region early this morning, which brought significant winter weather impacts to parts of our region yesterday. With the associated surface low pressure pushing into southeastern Canada, this is allowing the pressure gradient to relax and our winds to diminish. While it will be a cold morning, strong low level warm air advection (WAA) will push over the state and help to lift temperatures to the middle 20s over northeastern Iowa to the low 40s in southwest Iowa this afternoon. Winds from a southerly direction will increase and be sustained at 10 to 20 mph with gusts of 25 to 35 mph by this afternoon. These winds combined with whatever fresh snow fell on Thursday may be enough for streamers/blowing and drifting snow at ground level this afternoon over northwest into a bit of north central Iowa. Also today, the mid-level flow will become zonal and as a shortwave and surface low pressure tracks over the southern Canadian prairies, will see a cold front move through the state late tonight into Saturday morning. Cross sections and soundings show that the column overall remains too dry for any precipitation. This will, however, bring a glancing shot of cold air advection (CAA) that will make Sunday morning lows and highs lower compared to Saturday. Winds from the northwest will average 10 to 15 mph on Saturday and diminish Saturday night as surface high pressure moves over the state. With the light winds and a clear sky by Sunday morning, will keep an eye on possible fog development depending on the degree of melting that occurs on Saturday, which does not look excellent based on the forecast wet bulb temperatures. As the high moves off to the east, another round of low level WAA will develop Sunday night into Monday morning. Deterministic models all try to generate precipitation in this WAA regime to varying degrees over north central or northeastern Iowa or adjacent areas with cross sections showing some depth of saturation. Ensembles also support this idea and favor just to the northeast of the forecast area so will continue with initial National Blend of Models (NBM) that shows splotchy, low chances of light snow over southeastern Minnesota, far northeast Iowa, into southern Wisconsin.

As we move into the busy Christmas holiday travel period, there is high confidence in above normal temperatures and no signal for any significant, strong precipitation systems over Iowa. Mid-level ridging will build over the central US with the mid-level high over the western Gulf Coast States. The thermal ridge looks to peak over Iowa Christmas Eve into Christmas Day. Previous discussions have noted the NBM cold bias/slow to catch onto the warming trend and note that this NBM cycle is 5 to 6 degrees higher than the previous on Christmas Day. This could still be underdone with the 75th percentile of NBM nearing record high values over southern Iowa (Des Moines, Ottumwa) and below record highs by around 5 degrees over northern Iowa (Waterloo, Mason City). As for precipitation chances, they are slim with the ECMWF and Canadian as well as ensembles showing light QPF over eastern Iowa on Wednesday. Quite a bit of spread still so our forecast will carry no mention (<14%) at this time, but will be something will keep an eye on in the coming days.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 458 AM CST Fri Dec 19 2025

Winds from the northwest at the start of the period will become from the south by this afternoon and increase to 10 to 15 knots with gusts of 20 to 25 knots at the terminals. These breezy winds will remain into tonight, though winds and gusts will not be as strong as a cold front moves into the state. A period of low level wind shear will develop tonight diminishing near the end of the period.

DMX WATCHES/WARNINGS/ADVISORIES

None.