What’s Causing Wild Weather Out West?

At the start of the year, nearly 100% of the state was under a moderate drought or worse. Today, it's down to only a third.

LOS ANGELES, CA — If you asked a random person on the street about the weather in LA, they’d likely say: Sunny. Warm. Dry. Tornadoes probably wouldn’t be high on that list, but that’s exactly what happened Wednesday afternoon as a landspout tore through the eastern side of Greater Los Angeles.

And this isn’t the first time Californian weather has made headlines as of late. Mountainous portions of the Golden State have wrapped up one of their snowiest winters on record, with three to four feet of snow falling just since Tuesday.

“The snowpack’s expected to stick around probably into July, if not, into August at this point,” says Dr. Andrew Schwartz of the Berkely Central Sierra Snow Lab.

It’s all thanks to a series of powerful storm systems known as atmospheric rivers.

Atmospheric rivers are long, narrow bands of intense moisture that most commonly form over large bodies of water. They can transport water vapor equivalent to 15 times the flow at the mouth of the Mississippi River. When they get hung up over mountain ranges like the Sierra Nevada, they can dump several months’ worth of rain over the span of a few days.

And that’s exactly what’s happened. Thousands of residents south of Fresno were advised to flee their homes due to rising waters.

“We had conversations with the residents here a few days ago,” Chief Jake Castello of the Porterville Police Department told us. “They all evacuated voluntarily to the evacuation point of Porterville College.”

While we don’t want to see it coming in all at once, one of the worst droughts in California history has been all but quenched. At the start of the year, nearly 100% of the state was under a moderate drought or worse. Today, it’s down to only a third.