Extreme is definitely the best way to describe the rain and snow expected to inundate California and Arizona this week. One or more yardsticks will be needed to measure the snow set to bury the mountains of these two states. Ski enthusiasts will definitely welcome the snow but will have extreme difficulty reaching the resorts. In fact, travel will become nearly impossible in the passes.

Looking at the rainfall map, you can see that a yardstick could also be used to measure this week's rain across California. The heaviest rain will inundate the west- and south-facing mountain slopes, especially across Southern California.

Notice the deserts will not be exempt from substantial rainfall. Some places will receive at least half of their typically annual rainfall just this week.

It is then easy to understand why flooding is such a serious concern.

Story by AccuWeather.com Senior Meteorologist Kristina Pydynowski