A Winter Storm Watch includes most of Northwest Iowa Wednesday night through Thursday. This Winter Storm Watch highlights the area of the state we are expecting the most snowfall and the highest impacts from the winter weather.
Late Wednesday, the storm will begin with scattered showers, drizzle and fog expanding across Central Iowa. Scattered showers are expected after 11 PM and through about 5 to 6 AM on Thursday in Central Iowa. Snow will begin in western Iowa around 3 AM with a transition to freezing rain in western Iowa to rain falling along the I-35 corridor at that time.
The timing on the transition in the Metro of rain to snow will be dependent on when temperatures drop below freezing. As of Wednesday morning’s forecast, that looks to happen between 5 to 7 AM Thursday. This will lead to sidewalks and roads icing up ahead of the snowfall.
Snow will be ongoing in Western and Northwest Iowa and a band of 4 to 7″ of snow is possible in counties including, Guthrie, Greene, Boone, Webster, Wright and Hamilton Counties. Since the change to snow happens later in the Des Moines and Ames communities, snowfall amounts will be less.
The axis of heavy snowfall still could shift in the next 24 hours. We have to see how the path of the area of low pressure becomes more defined in the next 24 hours. That path will determine where the heaviest band will be. As of Wednesday morning predictions, it looks to take that heavy band through Greene, Boone, Webster, Wright and Hamilton.
There will be a strong push of cold air advection behind this storm system. That will lead to rapidly dropping temperatures to the low teens by Thursday afternoon and strong northwest winds of 15 to 25 mph. This could lead to blowing and drifting of snow. However, it depends on the type of snow which at this point, the snow looks to first fall as a heavy wet snow, which would limit blowing and drifting.
Snow will taper off during the afternoon and winds will lighten up which will help to improve any visibility issues.