West USA Air Mass

West USA has a Maritime Polar (mP) air mass; it's cool and moist.
Seasons in West USA vary.
The ones closest to us will have similar weather and season patterns. These places include Northern Arizona, Northern New Mexico, Southern Colorado, and Southern Utah. As previously stated, most high country Southwest USA seasons and weather are very similar. The desert areas like Southern Arizona, Southern New Mexico, and California have less distinctive seasons.
Spring and Fall weather for these places are more unpredictable. These times require inhabitants to be prepared as sudden changes are prevalent at these times of the year.

The Global wind that mainly impacts West USA is the prevailing westerlies. Most weather in the United States moves from West to East because of this.

Northwest USA (Oregon, Washington and Southern Alaska) will have orographic precipitation. These places are close to the sea; relief/orographic rainfall occurs when winds pick up moisture from sea as they travel across making the air most.  These places are commonly known for being wet, moist areas.
Southwest USA