Atmospheric rivers (AR) are long, narrow streams of water vapor in the sky, moving moisture from the tropics – carrying an amount of water roughly equivalent to the average flow of water at the mouth of the Mississippi River.
When the AR makes landfall, it releases rain or snow. The AR is a key factor in our water cycle.
According to NASA, atmospheric rivers off California's coast form regularly during winter months and usually deliver up to 50% of the region's annual rain and snow.
The "Pineapple Express," as it is called, brings moisture from Hawaii to the U.S. West Coast. It begins as a warm water storm over the Pacific Ocean, then prevailing winds give AR its shape and velocity.
The current series of AR is particularly treacherous due to the addition of low atmospheric pressure, which leads to the formation of an extremely powerful storm called a "Bomb Cyclon".
These two combined are responsible for creating the extreme storms which we are experiencing now.
We are just seeing the beginning of this weather pattern.
National Weather Service reports at least three more storm systems coming in during the next week. "Expect widespread flooding, damaging winds, and dangerous beach and marine conditions.”
Our severe drought will be slightly impacted but not eliminated.
Hunker down, remain current with forecasts, be safe, and stay protected.