A bomb cyclone and atmospheric river are developing in the Pacific. What does that mean for the West Coast?

The Northwest is bracing for a strong storm system to move in this week, delivering gusty winds, heavy rain and mountain snow. The National Weather Service says this is the first major storm of the season. An atmospheric river and bomb cyclone are what make this storm so powerful — but what do those terms mean? 

Atmospheric rivers are no strangers to the western U.S., especially during the fall and winter months. Atmospheric rivers, or "ARs," are elongated, narrow regions of moisture that travel outside of the tropical regions.