textproduct: Des Moines

KEY MESSAGES

- Accumulating snowfall (100% chance) will occur across parts of northern and northeastern Iowa from late this afternoon into tonight. A Winter Weather Advisory from around Algona over to Mason City and Waterloo remains in effect where snowfall totals, 2 to 4" are expected. The evening commute will likely be affected in these areas.

- A secondary cold front will move southeastward across Iowa on Wednesday afternoon, bringing strong and gusty winds, scattered snow showers, and blowing snow in areas that receive an inch or more today into tonight. Hazardous travel conditions are likely Wednesday afternoon and evening with near blizzard, to blizzard conditions possible!

- Very cold weather is forecast from Thursday night through Saturday. An Extreme Cold Watch has been issued for northern Iowa where the coldest wind chill values at or below -35F are expected. Other cold headlines are likely south of this region, and will be fined tuned in the coming day(s).

DISCUSSION

Issued at 320 PM CST Tue Jan 20 2026

This Afternoon and tonight...Snow continues to develop this afternoon across SD/MN and IA as the next clipper system moves into the region. Visibilities are just beginning to fall as of 330pm across northwest Iowa as stronger WAA/isentropic lift overspreads the area. There is a fair amount of dry air near the sfc, so onset time of the snow maybe delayed by an hour or two in some areas, but the overall impacts are not expected to change. Still expecting a band of 2-4" to develop from Algona to Mason City to Waterloo/Cedar Falls where the Winter Weather Advisory is in effect. Snowfall totals will taper off on either side of this band, with areas along and south of US 30 only expected to see a dusting. Snow ratios with this snow will be rather high 17:1 to 20:1 due to light winds and at least moderate lift within the snow growth or dendritic growth zone (DGZ). More on this below. Winds tonight should remain rather light, generally 10 kts or less, so blowing snow should not be an issue. With the southerly flow and WAA pattern, lows will be milder overnight, with single digits above zero in the north to around 20F far south.

Wednesday into Thursday...No rest for the weary. After the clipper system tonight, another wave is expected to drop swd across the upper Midwest on Wednesday. Ahead of this system expect a brief warming pattern with highs tomorrow topping out in the 30s to near 40 in the south, and in the upper 20s north. These highs will occur relatively early in the afternoon, before a potent cold front surges sewd across the state on Wednesday afternoon. Very strong winds are expected to develop behind the cold front due to deep vertical mixing for this time of year /to at least 850mb/ and a robust pressure gradient. Expect sustained winds of 20 to 30 mph, with peak gusts of 40 to 50 mph, locally higher in our usual wind prone areas. As noted above, with the light and fluffy snowfall expected in the north tonight, widespread blowing snow is expected to develop as the wind interacts with the blowable snowpack. In addition, the models are again suggesting an environment favorable for convective snow showers or snow squalls, due to steep low level lapse rates, modest CAPE /20 to 50 J/kg/ in the low levels, and saturation extending into the DGZ. As such, additional winter weather headlines are likely to be needed tomorrow. To avoid headline confusion with the event tonight, we decided to wait until after the current snowfall event to better fine tune the axis of heaviest snowfall. With the wind speeds anticipated, its possible blizzard or near blizzard conditions will develop by afternoon across portions of central and northern Iowa. Those with travel conditions will want to pay close attention to future forecast updates.

Extended...the main point...ARCTIC COLD. The coldest air of the season will into the region on Thursday night, and then persist right into the weekend. An impressive 1050 mb high will move across the area, with high temperatures likely to struggling to get above zero on Friday north of I-80. Per coordination, have issued an Extreme Cold Watch for about the northern 3 tiers of counties beginning Thursday night, where wind chill values will fall at or below -35F at times. Additional cold weather headlines are likely further south, which we will refine in the upcoming days.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1047 PM CST Tue Jan 20 2026

MVFR to IFR conditions continue across the northern half of Iowa. Snow has begun tapering off in western Iowa and will continue west to east over the next couple hours. Variable winds overnight will become westerly into Wednesday morning. By Wednesday afternoon winds will be strong out of the WNW gusting 30-40 kts across all sites. An area of snow will also move across northern Iowa, impacting sites KFOD/KMCW/KALO. The combination of falling snow and the powdery snow on the ground from tonight's accumulation with the strong winds will result in periods of near whiteout conditions. Winds will begin to taper off at the end of the TAF period.

DMX WATCHES/WARNINGS/ADVISORIES

Extreme Cold Watch from late Thursday night through Saturday morning for IAZ004>007-015>017-023>028. Winter Weather Advisory until 3 AM CST Wednesday for IAZ005- 016-017-025>028-038-039.