What is actually an atmospheric river?

.FOR CALIFORNIANS it felt like remembrance. In 2015 a procession of tornados, fed through atmospheric waterways, gotten rid of at least 21 folks and also caused virtually $5bn-worth of harm across the state. On February fourth this year the very same form of hurricane again created chaos.

Hurricane-strength winds buffeted the central shoreline near Significant Sur. In Los Angeles personalities were saturated as they came to the Grammy awards’ red carpet. Manors in the Hollywood Hills were actually covered in mud.

At the very least 3 folks have passed away. What are actually atmospheric rivers, and are they a risk past The golden state?