Weather In-Depth: Atmospheric River is not a gentle stream
ROCHESTER, N.Y. – We have calm, tranquil weather here in Western New York, but if the inclement weather is not here somebody has stormy weather. In this particular case, it is the repetitive nature of extreme weather that has a big impact for California. It is too much rainfall, coming too quickly. Just north of Los Angeles communities have measured anywhere from 6 to 12 inches of rain in just 48 hours. As a result, it has been significant flooding in this portion of the country.
However, this is not where the nasty weather ends. Move north towards San Francisco and it has been strong, damaging winds gusting in excess of 90 mph. This is hurricane force winds, especially in the higher elevations that is downing trees and causing power outages. Then there is the heavy snow in the Serria Mountains producing six to eight feet of snow.
The reason for this has been a series of storms coming off the Pacific Ocean over the past week that really “primed the pump” for the saturated the ground. You may have heard a specific type of terminology when describing this west coast weather. It is an atmospheric river that is the driving force for all of this moisture. This atmospheric river is very similar to a river you might find at the surface of the Earth. However, this is river of water vapor which is located tens of thousands of feet in altitude and is focused to be pushed inland. Where it is pointed is a determining factor for the heavy precipitation as it travels up the hillsides. As it climbs in elevation, that moisture condenses and is squeezed-out in for the form of rain and snow. Obviously, this is a problem for avalanche risk, mudslide and debris flows which can cause road closures up and down the west coast.