textproduct: Des Moines

KEY MESSAGES

- Light snow ending over the south by early this evening.

- Local fog possible overnight with some clearing into Tuesday.

- A strong cold front arrives late Tuesday night into Wednesday morning with falling temperatures and gusty winds. Very cold Wednesday night with all locations well below zero and wind chill values approaching 20 below over northern Iowa.

DISCUSSION

Issued at 221 PM CST Mon Dec 1 2025

Light snow band is moving across the southeast half of Iowa this afternoon though it is already beginning to diminish over parts of southwest Iowa. A few inches of accumulation remains possible over the far south central and southeast sections of the forecast area. Road conditions this far have remained only partly snow covered though some refreezing has been evident due to some melting and refreeze due to some solar radiation warming road surfaces enough or residual road treatments. This refreeze process likely will become more common after 4 pm as we move closer to sunset. A Winter Weather Advisory remains in effect for the southern area with the main accumulations. Will be removing counties as the event ends from west to east.

Once the snow ends, the forecast challenge for the overnight is cloud cover and low temperatures. Light south to southwest wind will develop overnight as the surface high pressure moves to the east with gradual warm advection developing. Clearing in the sky cover has been occurring this afternoon into northwest Iowa and over all of South Dakota and much of Nebraska. The stratus level steering flow will become more west to east overnight and that should lead to some clearing. That should lead to some cooling with the release of the cloud blanket but that will be minimized to some degree to the light southwest winds. It will be cold with many locations falling into the single digits to perhaps some low teens southeast where the clouds will linger the longest. Several raw guidance output suggest some reduced visibilities in fog late tonight into Thursday morning. A southwest wind of 5 mph or greater wouldn't support this so it will depend if the wind falls off with a brief weakness in the pressure gradient.

The next system to monitor is the Arctic cold front that will arrive late Tuesday night over northwest Iowa and through the rest of the area Wednesday morning. A period of light snow may occur as the boundary passes through with minor accumulations possible. High temperatures will be early in the morning then falling temperatures and gusty northwest winds of 25 to 35 mph will occur the remainder of the day. This wind may lead to enough blowing snow of the existing snow cover to lead areas with snow cover on roads again. The winds will subside Wednesday night as high pressure arrives. Very cold temperatures are forecast for Wednesday night and Thursday morning with lows of 5 below to 15 below. Some locations could bottom out and be colder than this where radiational cooling is maximized. Wind chills may be near 20 below over northern Iowa. Beyond this, some minor warming returns but we are in a winter type pattern so temperatures will remain below normal for the foreseeable future. Another change for snow may arrive this weekend as another wave drops southeast through the northwest flow.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 537 PM CST Mon Dec 1 2025

Stratus covers much of central Iowa this evening,including all TAF sites. At issuance ceilings under the stratus varied from VFR to MVFR and IFR, making for a challenging aviation forecast.Expectation is that ceilings will come down this evening and have included MVFR to IFR across all sites. There is a low chance for patchy fog to develop across northern Iowa overnight, but have kept from TAFs at this time due to low probability of occurrence. Improvement is expected through Tuesday as cloud cover diminishes from west to east.

DMX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until 9 PM CST this evening for IAZ074- 075-084>086-095>097. Winter Weather Advisory until 6 PM CST this evening for IAZ083- 092>094.