We have hearing more and more pronouncements by Governor Brown about the growing drought in California. I was doing some research to see what the impact the Pacific Decadal Oscillation (PDO) might have on local drought, or lack of drought, depending on the phase of the PDO. The PDO shifts between phases, from negative to positive and then cycles again. There was a cool PDO from 1900-1925, and 1946-1976, Warm phase from 1925-1946, 1976-2001. We are now in a negative phase. My question was, it there more rain and snow during a negative or positive PDO?
Here are some plots of Nevada City and Lake Spaulding precipitation, showing the warm phase periods in red.
Looking at the data my surprise was the increase in precipitation from the 1920 to 2013 in Nevada City and 1920 to 2003 in Lake Spaulding. The Lake Spaulding weather station stoped collecting data in 2003. Before 1920 many of the records in both Nevada City and Lake Spaulding stations had missing data.
It appears that with the slight increase in global temperatures, about 1.3°F (0.72°C) per century, the precipitation has increased in Nevada County rather than declining as the progressive warmer’s want us to believe.
When you look at the data history, note that significant years of drought have been followed by significant increases in moisture. Looking forward it appears California may be on the cusp of a La Niño, which usually brings more moisture to the state. You can find the details at Joe Bastardi’s Saturday Summary HERE.
In the past 150 years, California’s and local droughts have been relatively short in duration, about six years as shown in the late 1980s and early 1990s in the graphics. It looks like this one is going to be real short, according to Joe Bastardi. Prepare for winter snow!