Answer:
The major weather patterns at Crater Lake National Park originate in the
Pacific Ocean. Storm events originate in the north Pacific and build in
strength and moisture content over the ocean. Wind patterns at these
northerly latitudes move storms from the ocean to the Pacific Northwest.
Over 100 inches (250 cm) of rain falls
each year on the Oregon Coast. After crossing the Coast Range, storm
clouds descend into the Rogue and Willamette Valleys, dropping about 30
inches (76 cm) of rain. As storms move eastward, the high mountains of
the Cascade Range push the cool, moist air to elevations over 10,000
feet (3,000 meters) in many places. As the air rises, it cools further.
Water vapor in the air condenses to form clouds, and snow crystals form
within them. If there is enough moisture in the clouds, the snow begins
to fall. If the temperature is warm enough, the snow melts before it
reaches the ground and falls as rain.
