REAL COOL STORIES (week ended 2/3/24)
It wasn’t until the last year or so that I heard the phrase “atmospheric river” used in the context of storms approaching southern California.
So, what is an atmospheric river? Atmospheric rivers are relatively long, narrow regions in the atmosphere – like rivers in the sky – that transport most of the water vapor outside of the tropics. While atmospheric rivers can vary greatly in size and strength, the average atmospheric river carries an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River.
Exceptionally strong atmospheric rivers can transport up to 15 times that amount. When the atmospheric rivers make landfall, they often release this water vapor in the form of rain or snow.
The atmospheric rivers are usually between 250-375 miles wide. Most are weak systems that provide a little rain and snow in the mountains.
The strong atmospheric river that brings moisture to California is known as the “Pineapple Express”. The river travels from Hawaii to the US west coast. I thought Pineapple Express was the name of a great movie back in 2008 or a strain of marijuana from which the movie got its name!
What does that mean? Well, at least in southern California you can get a lot of rain (relative to norms) in a short period of time, but it can also create the river effect that keeps rain (or snow in the mountains) flowing for several days.
Last year, San Diego recorded its wettest season (October 1-September 30) since 2004-05. We had a couple of atmospheric rivers which created large storms. The official 2022-23 rainfall at the San Diego airport was 15.71 inches.
California was hit with a Pineapple Express storm on February 1 and another is expected right behind it. Rainfall totals exceeded an inch in most parts of San Diego and LAX recorded almost 2.4 inches. The official 2023-24 rainfall at the San Diego airport year to date is 5.79 inches.
It's fun to learn about your local weather and why terms are used.
A real cool story indeed!