Winter Storm Watch Now in Effect

 A Winter Storm Watch is in effect on Monday from 6:00AM until 6:00PM for Ogle, Lee, Boone, McHenry, and Winnebago Counties. For Carroll, Whiteside, Jo Daviess, and Stephenson Counties, the Watch goes until Tuesday morning at 6:00AM. For the counties in Southern Wisconsin, the watch is in effect until 9:00PM Monday evening. You can see that watch to the left. Every county shaded in blue is included in the watch.
The reasoning behind the issuance of the watch is a very large, strong and expansive storm system is getting its act together in Texas tonight. It will continue to strengthen as it begins to move quickly towards the northeast, which ultimately takes the low pressure center over Eastern Iowa and then Central Wisconsin. The system has already produced multiple tornadoes--some of which have been extremely strong, deadly and violent--reported this evening in Texas and Oklahoma. Some of those moved through the Dallas area, where several communities were flattened. On the other side of the state of Texas, there are Blizzard Warnings in effect for upwards of a foot or more of snow and winds gusting to 60mph.

With those two extremes, you can see how strong and potent this storm system is. The map to the left shows the current watches and warnings. Nearly every color on this map is a watch or warning associated with this storm system. There are Flood Warnings, Tornado Watches and Warnings, Blizzard Warnings, Winter Storm Watches and Warnings, Ice Storm Warnings, and more currently as a result of this major storm system.
Areas seeing the wintry side of this system will be seeing significant snowfall, freezing rain, sleet, or a mixture, in addition to very strong winds. Regions seeing the rain and thunderstorms with this system will see several inches of rainfall, the potential for flooding, and the potential for severe weather.

For the Stateline, the wintry side of the system will impact us for a long duration before slightly milder air works its way in and changes the wintry precipitation to plain rain where temperatures surpass the freezing mark Monday evening. The precipitation will begin as snow, sleet, freezing rain, or a mix Monday morning around sunrise and quickly overspread the region from south to north.

The precipitation will turn moderate to heavy during the morning into the afternoon hours. During this time frame, the majority of precipitation will be falling as freezing rain, which will allow a significant amount of ice to accumulate with such high rates of precipitation. Temperatures will slowly rise through the day into the lower 30's by afternoon. The exact location of the freezing line will be crucial in determining who sees what kind of precipitation, and, as a result, how much. Around 4-7PM, most locations, especially the southern and eastern counties, will be above freezing. That will alleviate some of the icing problems, and it will allow plain rain to fall.

Nonetheless, this event will be a significant winter storm. Locations south and east of Rockford will likely see 0.1-0.2" of ice. Winnebago County will see upwards of 0.25" of ice. Counties to the north and especially the west of Rockford will see 0.2-0.3"+ of ice. Sleet accumulations are possible as well for the entire region, but that is not expected to be significant. Snow accumulations are possible as well, especially towards the end of the system into Tuesday early morning. Most of the snow accumulation, if any, will be confined to areas from Rockford and points north and west. A few regions could see a half inch to a couple of inches of snow before the time the precipitation comes to an end.

The system will come to an end by 5-9AM on Tuesday morning, but troublesome travel is expected Monday into Tuesday morning for much of Northern Illinois and Southern Wisconsin. It is important to remember that this forecast could change quite a bit if the low pressure takes a track even slightly different than what is projected now. If the low moves further south, we will see more cold air, which means more snow and frozen precipitation. If the low edges north at all, we will see warmer air and more rainfall.