Mandatory Winter emergency Kit for soldiers:

First aid kit (Mandatory year round)

Road Flares

3 days of food (MRE's work great, one MRE is 3000 calories, don't need to carry many of them to last for a long time)

water

a sleeping bag

warm clothing (Polypro underwear in most cases, REALLY warm, and at about $9 for a shirt and $8 for the pants, cheap)

a shovel, and sand.

Most of us add a tool kit of some sort.