Try as you might, you’ve probably lost track of the more than 30 atmospheric river storms that have swept into the Golden State since Oct. 1. But that’s not true.
The animation above shows every atmospheric river storm that has hit the west coast since the start of the water year on Oct. 1. The data used in this animation was provided by the Center for Western Weather and Water Extremes (CW3E). The color of each storm indicates its strength, with black being the strongest level.
And this year has been a doozy: In Northern California, we’ve already had 7 strong or stronger storms in the region, according to data from CW3E. That’s significantly above the average of 4.7 for this time of year based on data going back to 2012.
In central and southern California, where atmospheric rivers are generally less common, this season was even more unusual. In a typical year, the two regions are hit by an average of 1.7 strong or stronger storms. But this season they have already been hit by 4.
Not all of the atmospheric rivers on this map made it to California, and many that crossed the border weakened significantly by the time they crossed state lines. At the beginning of this week, California had experienced 31 atmospheric rivers, entering the state with the following strengths: 11 weak, 13 moderate, 6 strong, and 1 extreme, which hit California on December 27 after landing in Oregon as exceptional – the strongest level.
There is widespread disagreement among experts about what constitutes an atmospheric river, and CW3E’s estimate for 31 storms is higher than many others. It also includes atmospheric rivers that cut the state’s border, but did not produce sustained rainfall.
We’ve been hearing the term “atmospheric river” a lot more lately because they’re so important in supplying California’s reservoirs and snowpack with the water needed to end drought in a thirsty agricultural region. state with 40 million inhabitants. In 2019, scientists at UC San Diego’s Center for Western Weather and Water Extremes developed a 1-to-5 system to rate power of these gigantic conveyor belts of water in the air, of which 5 is the strongest.
Atmospheric rivers carry twice as much water per second as the Amazon River and 25 times the volume of the Mississippi where it flows into the ocean. Here’s a look at how that rating system works.
Staff writer Paul Rogers contributed to this report.