Ready Wisconsin - (the state averages about 47 inches of snow a year) - and some other resources - offer the following suggestions for your own emergency kit:

Warm clothing, to be used if you need to change
Non-perishable food (e.g. nuts, canned tuna, crackers, dry cereal, fruit cups)
A flashlight and extra batteries
Prescription medications
A fully-charged phone and phone charger
Ice scraper
Jumper cables
Extra gas
Battery powered radio
Cat litter, sand or rock salt to use for traction to get tires on the road|
Bottled water
Diapers, other items needed for infants
Tissues and toilet paper

Another tip: If you do have to abandon your car, leave something with your name, phone number, address and destination in the window.