[californiadisasters] Past Rainfall Shows La Niñas Are Not All Alike

Past rainfall shows La Niñas are not all alike

By John Lindsey
San Luis Obispo Tribune

Published: Sunday, Jan. 09, 2011 

As widely reported last year, La Niña was supposed to produce below-normal rainfall this year. Our experience so far this winter reminds us that not all La Niñas are created equal.

La Niña, which generates cooler-than-normal sea surface temperatures in the central and eastern equatorial Pacific, usually produces below-normal rainfall. According to meteorologist Jan Null's studies (http://ggweather.com/enso.htm), the long-term rainfall average during La Niña events is about 87 percent of normal on the Central Coast, and even less in Southern California — about 70 percent — as the storm track is shifted northward.

The Cal Poly rain gauge (the official home for climatology records in San Luis Obispo) recorded 9.66 inches of rain in December. That's the wettest December since 1996, which produced 10.88 inches of rain.

So far this rain season, Cal Poly has recorded 13.25 inches of rain, or about 175 percent of normal. Even if it didn't rain again until the end of the rain season in June, San Luis Obispo would finish at 57 percent of normal.

The rain gauge at Diablo Canyon nuclear power plant has recorded 17.61 inches, or about 200 percent of normal. SLOweather.com (an informative local weather site) in the Irish Hills on San Luis Obispo's Westside has already recorded 20.43 inches of rain, or 250 percent of normal.

As you head further south, the percentages of normal rainfall increase.

The Santa Maria, Santa Barbara and Los Angeles airports had their wettest Decembers on record, and each airport was near or over 500 percent of normal rainfall at the end of the year.

The lake and reservoir levels of San Luis Obispo County have significantly increased over the last few months. As of last Friday, both Lake San Antonio and Nacimiento Lake were at 53 percent of capacity, Whale Rock Reservoir was at 60 percent, Lopez Lake reached 70 percent and the Salinas Reservoir near Santa Margarita was over 100 percent and spilling.

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View entire column here: http://www.sanluisobispo.com/2011/01/08/1436163/past-rainfall-shows-la-ninas-are.html#ixzz1AZbbDL2Y

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