This replaces `atmospheric river` with `big storm`. "Why?" You might ask. Because `atmospheric river` sounds stupid and is stupid.
Sure "atmospheric river" might make sense as scientific jargon in some meteorological research paper, but in a colloquial context its just dumb.
The phrase has exploded in popularity because news outlets have discovered it makes a clickbait-y headline
that SEOs well. Fixing this affront to our dignity I promise will improve your news viewing experience.
This is a real world example of the Onion "post office box" phenomena:
https://www.youtube.com/watch?v=uFpK_r-jEXg