Flood alerts were issued on Monday morning (Feb. 19) for Santa Barbara and Ventura counties in California, where 5 to 12 centimeters of rain had already fallen, according to the National Weather Service.
More than 37 million people are under flood alert. The heaviest rains are hitting Southern California.
Airports and roads have been closed due to flooding. Santa Barbara Airport was closed due to flooding on Monday morning. A flooded section of Highway 246 was closed in both directions on Monday morning in Santa Barbara County, with no estimated reopening. A section of Highway 1 in neighboring San Luis Obispo County was also closed on Monday.
The Weather Prediction Center issued a forecast for excessive rain through Tuesday for much of California. Major cities facing the highest flood risk in the coming days include Los Angeles with a level 3 out of 4 risk on Monday and a level 2 out of 4 risk on Tuesday, and Santa Barbara with a level 2 out of 4 risk on both Monday and Tuesday.
Why so much rain in California?
The intermittent rains in California are a consequence of a phenomenon called ‘Atmospheric River,’ a scientific term given to the bands of moisture that Pacific winds blow over the West Coast. Frequently causing heavier rains and flooding in California.
Atmospheric rivers can occur almost anywhere in the world, but they are most notable in the United States and the West Coast.
And while only 17% of storms on the West Coast are caused by atmospheric rivers, they contribute to 30% to 50% of the total precipitation that falls in the state. They also contribute to 40% of the Sierra snowpack and over 80% of the state’s major floods, according to a NASA study.
Atmospheric rivers are predictable and can sometimes be forecasted up to a week in advance, says The Weather Channel.
Source: CNN and CBS News