California is currently grappling with an extraordinary weather phenomenon known as an ‘Atmospheric River’. These streams in the upper atmosphere carry copious amounts of moisture and have the potential of striking catastrophic deluges for hours together or may even extend further. These channels of atmospheric water are also referred to as ‘ Pineapple Express’ and are backed by very heavy downpours, lasting for over 24 hours.
The atmospheric river is a long, narrow band of moisture-filled air that transports abundant amounts of water vapours from the tropics to higher latitudes. Since these streams originate over the oceans, it is difficult to capture the phenomenon by pure synoptic means. However, the weather satellites carrying typical sensors can catch the signatures and reveal their devastating potential. One such development, revealing swirling movement in the Pacific Ocean, off the coast of California was encapsulated, genuinely assessing the fierce potential of ravaging the land areas.
The intense rainfall with heavy snow in high elevated mountains, was carried to California by the atmospheric river, a vast current of dense moisture funneling from the Pacific to South California. Nearly a foot of rain was measured over 24 24-hour period at the University of California- Los Angeles. Earlier, a less powerful storm hit California, last Wednesday and Thursday, also qualified as ‘pineapple Express’ originated from the warm Central Pacific waters of Hawaii.
Atmospheric rivers have unleashed havoc in California. There are floods, chaos, and power outages leading to the declaration of emergency by the Governor in eight counties. Los Angeles has recorded the 3rd wettest February since 1877. A number of upscale communities built on the slopes of the Hollywood Hills, Beverly Hills and Topanga Canyon were among the hardest hit by landslides/ mudslides. The danger is not yet over and caution needs to be exercised. Wait and watch for the next couple of days.