We've got highway closures all over the place this winter too. In fact, there's one North of me and one East of me as I type this response.

My top 10 must haves for a potential overnight in my Jeep during solo winter travel, aside from the standard vehicle & First Aid kit stuff are:

-extra sweater and/or coat (My old long heavy wool coat lives in my Jeep right now)
-cold weather sleeping bag (rated for the lowest temps you could see)
-extra WARM hat and mitts (right now, I've got a fur-lined trappers hat and snowmobile gloves)
-snow pants
-snowmobile boots
-fresh hot drink in insulated mug/bottle (usually coffee or hot chocolate)
-corn shovel
-extra washer fluid
-phone charger
-my Get Home Back/Winter Day Hike kit (It's a bit of a cheat for a top ten list, but here's a look at the current contents: http://www.youtube.com/watch?v=5pnoNOdK2yc)


When the family comes with me, we load up extra warm stuff, snacks, drinks, etc. for them too. Everyone takes a BOB/GHB when we travel any distance in the winter!