CHICAGO - The blizzard that blasted Colorado and shut down Denver's airport swept through the US Midwest on Thursday, leading to at least two weather-related traffic deaths and dumping up to 12 inches (30 cm) of snow in Wisconsin, officials said.

Two men walk in the snow in downtown Sioux Falls, S.D., Wednesday, March 23, 2016. A powerful spring blizzard stranded travelers at Denver's airport and shut down hundreds of miles of highway in Colorado, Wyoming and Nebraska as it spread into the Midwest on Wednesday. [Photo/IC]

A woman and her 15-year-old sister died when their van crossed over the median of a slippery highway in the city of Hartford around 11:10 am local time and crashed into an oncoming semi-truck, the Washington County Sheriff's Office said. The truck driver, a 61-year-old from Ontario, Canada, was not injured.

National Weather Service meteorologist Bob McMahon in Milwaukee said sleet was falling in Washington County before it received as many as two inches of snow by the evening. McMahon said northern and central Wisconsin bore the brunt of the storm, pummeled by a band that dropped up to 12 inches (30 cm) of snow.

Wisconsin Governor Scott Walker declared a state of emergency on Wednesday in response to severe winter weather and blizzard conditions.

Snow is predicted again for parts of Colorado late on Friday and Saturday, but conditions will not be as severe as they were on Wednesday, when areas of the state saw up to more than two feet (60 cm) of snow and the Denver International Airport shut down, National Weather Service forecaster Andrew Orrison said.

"We're not expecting snow like what we just had," Orrison said.

A cold front moved across Louisiana, which received heavy showers and thunderstorms in the southeastern part of the state, Orrison said. The rain had dissipated by Thursday afternoon, forecasters said.

A tornado watch was in effect until 7 pm CDT on Thursday for the central Gulf Coast region, from Gulfport, Mississippi, to Panama City, Florida, in the western half of the Florida panhandle, forecasters said.

In addition, Mobile, Alabama, issued a flash flood warning that was in effect until 4 pm CDT on Thursday after the airport there saw more than 2.5 inches (5 cm) of rain in about 1-1/2 hours, a forecaster said.