Here's a new weather phenomenon for me. From the local SLO Tribune, apparently during strong El Niño events, when eastern Pacific seawater temperatures are warmer than normal, the central California coast has historically experienced above-normal rainfall. During weak El Niño events there doesn't seem to be much effect on our total rainfall.
The last two strong El Niño events along the Central Coast occurred in 1982-83 and 1997-98. Water temps reached 62.5 degrees in September '83 and an all time record of 63.6 degrees in October of '97
The seasonal rainfall in San Luis Obispo averages about 25 inches. During the 1983 rain season, over 47 inches of rain were recorded in San Luis Obispo, and over 44 inches were tallied in 1997.
On the flip side of El Niño is a La Niña — below normal seawater temperatures in the eastern Pacific. La Niña tends to bring below-normal rainfall amounts, but during a La Niña cycle in 1995, over 8.5 inches of rain fell in less than 24 hours on March 9 and 10. This caused significant flooding throughout San Luis Obispo County. So the truth is, sometimes we really don’t know what is going to happen.
Over the last two rain seasons we’ve experienced below-normal rainfall, which seems to correspond with below-normal seawater temperatures. This April, the mean ocean temperature was 49.5 degrees off Diablo Canyon, which was the coldest on record.
The cool waters along the Central Coast right now are part of a larger climate phenomenon known as the Pacific Decadal Oscillation. Unlike La Niña and El Niño, which last only a year or so, the PDO only changes once every five to 20 years. This cool phase of the oscillation often produces below-normal rainfall.
Looks like the drought continues!
No comments:
Post a Comment