Forecasters have updated the winter storm watch to a winter storm warning for the entire tri-state area from noon Tuesday, Dec. 29, to noon Dec. 30. 

The warning area includes Clayton, Delaware, Dubuque, Jackson and Jones counties in Iowa, Jo Daviess County in Illinois and Crawford, Grant, Iowa and Lafayette counties in Wisconsin, according to the National Weather Service.

The weather service says that a winter storm will spread across the region Tuesday afternoon, with 6 to 9 inches of snow expected locally. 

"During the heaviest period of snow, from late Tuesday afternoon through midnight, peak snowfall rates are likely to reach 1 to 1.5 inches per hour, especially for locations north of I-80," the NWS states.