ROCKFORD (WREX) Chilly air flows into the Stateline Thursday, dropping temperatures into the teens for the first time since November. When we warm back up, snow showers come with the warmer air.
Temperatures Thursday morning will barely be above zero. Wind chills start out the day below zero. By Thursday afternoon, temperatures try to get back to 20 degrees. Wind chills by then warm to the single digits above zero. At the very least, we'll see a sunny and dry sky and avoid drizzly, foggy weather for a day.
A storm system brings warmer air back into the region Friday, but the warm air is just a side effect to the snow showers on the way.
Winter Storm Watches were issued by the National Weather Service ahead of the storm to highlight where heavier snow is possible, if not likely. The Watches cover large sections of Iowa, Minnesota, and Wisconsin, and include Stephenson, Jo Daviess, Carroll, and Whiteside counties in northwest Illinois. Consider the watch your "head's up" that heavy snow and ice may be on the way Friday evening through Saturday.
While models still disagree on some details, the broad picture shows snow showers arriving Friday afternoon across northern Illinois. The showers may become heavy Friday evening. By midnight, warmer air floods the region, allowing the snow to turn over to rain. However, surface temperatures stay below freezing for a while. As a result, snow turns to sleet and freezing rain for a while. This could lead to ice accumulations on top of the snow.
After sunrise or so Saturday, everything should warm up enough that regular rain showers sneak in for a while. By the end of the morning, the showers may turn back to a rain/snow mix or light snow as the storm departs.
Again, since this is a complex storm system, there are a lot of moving parts that need finalizing. Stay up to date on the forecast with the 13 Weather Authority throughout the week.