Approaching the U.S.’s Thanksgiving holiday with heavy mountain snows to the West, slowing drivers through the Rockies. That’s the leading topic, but there’s a lot more to get to in this week’s Weather Watch. A significant arctic outbreak will arrive in the northern Rockies and Northern Plains on Thanksgiving into Friday and advance farther south and east through much of the Plains and Midwest this weekend. Dangerous wind chill temperatures are expected with a significant long duration lake effect snow event possible downwind of the Great Lakes. Severe thunderstorms may be possible in the Southeast. Heavy precipitation stretches across British Columbia and Alberta and freezing rain with snow squalls for Ontario and Quebec.