The National Weather Service overnight has upgraded a Winter Storm Watch to a Winter Storm Warning, meaning most of northern Indiana and southern Michigan will see snow accumulations of from 6 inches to 12 inches, beginning late tonight and early Sunday morning. Forecasters are calling this a potentially deadly winter storm.

The upgraded winter event will bring with it bitterly cold, life-threatening conditions bottoming out at negative 16 degrees Sunday night, with a windchill making it feel like minus 45.

Snow is expected to begin falling around 1 a.m. Sunday bringing blowing and drifting of about 2 inches to 4 inches overnight. Conditions will continue into early Monday morning bringing up to 12 inches of snow in some locations. Extremely cold temperatures and deadly wind chills will be on tap Sunday night through Tuesday.

The National Weather Service discourages unnecessary travel during this storm, but says if travel is necessary, be prepared for emergencies by packing extra blankets, food, water, a shovel and make sure you plenty of fuel.

With temperatures this cold, a person can suffer frostbite in 10 minutes at wind chills of 45 below zero. Animals are also vulnerable to the cold and should be brought inside during the next few days to prevent exposure.