The technical definition is - "A long, narrow, and transient corridor of strong horizontal water vapor transport that is typically associated with a low-level jet stream ahead of the cold front; especially along the Pacific coast states. (Atmospheric rivers are the largest "rivers" of fresh water on Earth, transporting on average more than double the flow of the Amazon River.)"
Well, that made it as clear as mud. Let's see if I can get it as clear as milk. Ever heard the term "pineapple express"? Well, that's a form of an atmospheric river (AR). An AR can be as wide as the states of Oregon and Washington combined, or as narrow as a few miles. They can dump copious amounts of rain as they don't tend to move very much. As the front (the boundary between cold and warm air) eventually shifts south, the AR "tap" gets severed.
You crack me up Shuhak. You must be a mind reader. As I was reading the first paragraph I was thinking something along those lines. Clear as mud. Too funny. But yes m'dear I have heard of Pineapple Express. Of course I would. It's refers to a type of food! Kinda joking but maybe somewhere along the line in life I've read it but it just didn't connect. Thank you for the explanation. I think our storm is over and it wasn't as hugely big as I thought it would be. Some folks had to be evacuated in burn areas..MANDATORY. It rained in stages. It would stop for an hour or two and then start up again. I expect our mountains will be beautiful laden with snow. Happy Saturday Shuhak! :)
This post was edited by RosieG at January 30, 2021 11:09 AM MST
Atmospheric rivers can (and do) occur in Europe. In fact, they can occur anywhere in the world (outside the tropics, of course). However, they are most common in the mid-latitudes (both hemispheres).
Shuhak 