This storm system looks to have a high amount of moisture for a January snow which could lead to some moderate or high snow totals in Northern Iowa. It is also very dynamic with a changing temperature profile, leading to periods of snow to periods of freezing rain and rain in some areas of the state.
Snow begins in Iowa, lifting in from the the south and west. It will be cold enough for snow and it will come down heavy through the late morning through afternoon. Snowfall should accumulate quickly with a couple early inches over most of Iowa.
Warm air will start advecting into southern Iowa during the afternoon. This will lead to lower snow amounts in southern Iowa and slick conditions developing. Further north, it will remain colder and snow will continue. Travel will be difficult across the state on Friday.
We will continue to see warmer air pushing in over southern and western Iowa. We could even reach the mid-30s in these areas. There will be a mix of precipitation at that time including freezing rain, sleet, rain and drizzle. This will limit accumulation in the areas that see the mix of precipitation. The precipitation will also become lighter at this time.
Overnight Friday-Saturday Morning
The main center of the storm system will push east of Iowa through early Saturday morning. Much colder air will start to rotate into the state from the northwest. Another push of snowfall is expected with the arrival of the colder air. There may be some minimal accumulation with this. Strong northwest winds will lead to blowing and drifting of snow. Travel will remain hazardous through Saturday night.
In general 3 to 6″ of snow, especially north of I-80 looks to be possible, with Des Moines at the lower end of the range, around 2 to 4″. Lesser amounts in southern Iowa where there may be periods of rain and freezing rain and drizzle. The higher amounts, up to 6″, look focused on northern Iowa.