In the winter I like to add some trail mix.
Deez nuts, eh? Or rather doze nuts, in past tense.
That's actually a really good idea, having some carbs and calories ready in the vehicle, just in case. It sure is better than nothing, if that's the alternative. So I hope you don't mind if I steal that idea.
I have been nearly stuck at a mountain crossing once - entry gate was open, but the weather got worse as I crossed it, so when I got to the other side...the exit gate was closed. And it was snowing, blowing and getting darker. I was alone in the car, no other cars in sight, and no cell reception. I stayed there for some 45 minutes before a snowplow truck came to check if anyone was up there, with keys to the gate.
The driver told me that was the last trip he would make up that day, so I felt really damn lucky. I had plenty of water with me, and some food and warm clothes (was packed for a trip to the family cabin, but not packed to spend a night in the car), and enough fuel in the tank to keep the heater going when needed, but I was already well ready to attach a tow rope to the gate and step on it, because part of me was really pissed off. I checked the conditions for the area beforehand, and it said nothing about even potentially closing that crossing that day.