UNDATED (WHBL) - A major winter storm will likely throw a wrench into some holiday travel plans in the state. The National Weather Service in Sullivan has issued a Winter Storm Warning for the entire southern portion of Wisconsin, from 9pm Saturday through 6pm Sunday. The weather service says a low pressure system will strengthen rapidly, bringing heavy snowfall with it. Six to nine inches of snow is expected. Roads will likely be icy and snow-covered. Officials say commuters should take extra caution while driving.