Eli5: if a rain storm (in nor cal, an “atmospheric river”) drops 5 inches of rain in a day, where does the extra moisture come from to keep deluging places east with snow or rain?

Question

It seems like itd run out of steam, and since its so cold, theres minimal evaporation. Wheres the water come from?

In: 0

Answer 1

Some moisture makes it over the mountains. Not as much, but enough to snow on the Rockies, so long as there’s enough atmospheric forcing to condense the moisture into snow.