Sure, the motor powering the door will not be able to overcome the resistance of even a few inches of snow outside. Think of the bottom edge of the door as the tip of a lever's long side. It is the opposite of what you want when using a lever. The long side is for applying power and the short side gives you the extra torque you need.

Put more simply, the door won't be able to push snowdrifts out of the way if it has to swing outward to open. Your 4x4 with snow tires will remain stuck inside the garage, unable to exit.

EDIT - After re-reading the question I now realise the comment above was about modifying this particular design to open outward at the top, and I was (incorrectly) assuming it was about a traditional outward-opening door like you might see in southern California. Sorry for the confusion. That may still be problematic, but not for the reasons I gave here.