What is an atmospheric waterway?

.FOR CALIFORNIANS it seemed like familiarity. In 2013 a parade of tornados, sustained through atmospherical rivers, killed at the very least 21 individuals as well as resulted in nearly $5bn-worth of harm all over the state. On February fourth this year the same sort of tornado once more ravaged.

Hurricane-strength winds buffeted the central coast near Significant Sur. In Los Angeles stars were actually soaked as they got to the Grammy honors’ welcome mat. Manors in the Hollywood Hillsides were actually covered in mud.

At the very least 3 people have perished. What are actually atmospheric rivers, and also are they a hazard past The golden state?