textproduct: Des Moines

KEY MESSAGES

- Colder temperatures moving in today through the weekend. Wind chill values in the -20s to -30s possible Saturday night into Sunday.

- Accumulating snow potential returns late Friday night into Saturday. Snowfall amounts generally around 1 to 3 inches are expected, with a band of 3 to 5 inches possible.

- Warming trend through next week.

DISCUSSION

Issued at 336 AM CST Fri Dec 12 2025

With snowfall having departed the area last evening, conditions are generally quiet over Iowa early this morning. High pressure is building in overhead, with stratus clouds socked in over most of Iowa, indicative of the moisture stream embedded within the our persistent northwest flow. Today will generally be cool and cloudy, with winds increasing later this afternoon as a cold front pushes into the state.

As we get into Friday night, a 500 mb low will dive southeastward over southern Canada and into the Great Lakes region, reinforcing the cold air and bringing the potential for accumulating snowfall Saturday. A healthy band of frontogenetical forcing around 700 to 600 mb will be the focal point for the snowfall on Saturday, oriented from northwest to southeast through central Iowa. For much of the area, soundings and cross sections indicate that this lift will fall outside of the dendritic growth zone and within a slightly warmer layer of the vertical profile. Snow will still occur in these areas, but likely won't be as efficient as the cold profiles may imply, likely in the 10:1 to 15:1 range with snowfall amounts around 1 to 3 inches. That said, while most of the lift on Saturday appears to fall outside of the DGZ, not all of it does. Cross sections do show a small area of overlap where the strongest frontogenetical forcing occurs within the DGZ. A "goldilocks zone", so to speak. This will be the area to watch for, as this is where more efficient snowfall will be most likely to occur, boosting rates and snowfall amounts beneath it. Snow to liquid ratios around 20:1 or higher will be possible in this band, resulting in snowfall amounts in the 3 to 5 inch range. Although the area of 3+ inch amounts likely won't be large, have went ahead and put out a Winter Weather Advisory for areas that are most likely to experience this band of heavier snowfall amounts. Expansion or adjustments of the advisory may be needed should the expected location of the band shift.

Cold temperatures will accompany the snow on Saturday, with highs only reaching the single digits. Temperatures will continue to plummet into Saturday night and Sunday morning, as the high pressure center sits overhead. This will drop lows overnight Saturday into Sunday morning into the teens and single digits below zero, with wind chills into the -20s and even -30s over far northwestern Iowa. Cold weather headlines will likely be needed in the coming days. Fortunately, this cold weather doesn't stick around too long, as the pattern looks to shift warmer as ridging moves in next week.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 523 AM CST Fri Dec 12 2025

MVFR to IFR stratus is impacting or will impact all sites this morning. Some light fog is also being observed, with visibilities generally around 3SM to 5SM at Terminals, although even lower visibilities are being observed in southwest Iowa. These aren't expected to impacts any of the TAF sites. Stratus sticks around through mid-day, but should lift into VFR for a period this afternoon and evening. Likewise, a cold front will pass through the area this afternoon, bringing breezy winds around 10 to 15 kts and gusts up to 25 kts possible at times. Finally, snow chances move back into the area early tomorrow morning.

DMX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory from midnight tonight to 3 PM CST Saturday for IAZ023-033>036-044>048-058>060. Winter Weather Advisory from 3 AM to 3 PM CST Saturday for IAZ049-061-062-073>075-085-086.