A significant snow and icing event is on the way today as a surface low moves through the area. The entire state is under a Winter Storm Warning for the majority of the day today due to either heavy snow or icy conditions. This is a very tough forecast to nail down due to considerable model differences with last evenings model set. The American NAM and European ECMWF continue to edge this event further east than previously anticipated and that is why we have moved the heavier snow accumulations out of extreme northwest Iowa and into more of northeast Iowa. The track of the low aforementioned will ultimately be the deciding factor in how well everyone’s forecast will play out with media outlets and different weather service offices having different thoughts and idea. Ultimately, our forecast has always leaned toward the ECMWF and NAM blend solution, and that is what we are going to stick with for the time being.

A lot of precipitation will be involved with this system, however some dry air will have to be overcame first during the day. The bulk of the heavier precipitation will be in the afternoon when additional forcing sets out across the area. Snowfall rates of one-to-two inches per hour can be expected with potentially higher totals in the convective bands. We have bumped the high end of totals across the forecast area to eight-to-ten inches with at least four inches expected for the bulk of the state, with the exception being the far southeast where ice will exist. At least a quarter of an inch of ice can be expected for southeast Iowa with the heavier totals being in the southeast where around a half inch is possible.

Winds will only make a very hazardous situation even worse with a tightening pressure gradient as the low moves in and winds pick up to about 20-25 MPH sustained. Gusts will be up to 40 MPH. This could create blizzard-like conditions across the area. This is particularly dangerous in the southeast where a lot of ice on power lines and trees will get blown around by these high winds and potentially topple. Roads will range from slippery in some places, to impossible, where ice and snow combine and create a very dangerous situation. Wet and rapidly falling snow will quickly pile on and create hazardous driving conditions, especially in areas where ice will also exist. The heavy snow threat is especially great on Interstate 35 north from Ames to the border, and in southeast Iowa.

This storm will likely be one of the nastiest ones of the year. Rapid effects can be expected shortly this morning. Road closures can be assumed, and hopefully businesses, schools, and other organizations will be closed today. Please stay home, stay safe, and do not travel unless you absolutely need to. Stay tuned to the Iowa Weather Network throughout the day for the latest information.