GMC Sierra Denali Owner's Manual page 249

If You're Caught in a Blizzard
If you are stopped by heavy snow, you could be in a
serious situation. You should probably stay with
your vehicle unless you know for sure that you are near
help and you can hike through the snow. Here are
some things to do to summon help and keep yourself
and your passengers safe:
4-40
Turn on your hazard flashers.
Tie a red cloth to your vehicle to alert police that
you've been stopped by the snow.
Put on extra clothing or wrap a blanket around you.
If you have no blankets or extra clothing, make
body insulators from newspapers, burlap bags, rags,
floor mats
-
anything you can wrap around
yourself or tuck under your clothing to keep warm.
.
_ - .
I : .
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You can run the engine to keep warm, but be careful.