There is a very specific meteorological process that is responsible for California's current record-setting drought. There is a high-pressure zone off of the West Coast that is much larger than they usually are - a mind-blowing 2,000 miles long and 4 miles high! This causes any winter storms from the Pacific from hitting California like they usually do in the winter (due to its Mediterranean climate, California often has rain-less summers and most rain in the winter from a few large storms). Instead, the storms are being deflected up to Canada and Alaska, and sometimes traveling back down to the East Coast.
It's not that California never gets these high-pressure zones blocking its rain, but usually they only last a short time. This current one has lasted 13 straight months! Scientists aren't sure why the ridge is lasting so long, but it is causing some drastic effects. Last year was the driest year in California's recorded history (160 years), and the Sierra Nevada snowpack is 20% of what it normally is. (I'm sure the ski resorts are hurting bad). Reservoirs across the state are only 30-36% full, which means water rationing may occur soon unless they get several big storms.
http://www.mercurynews.com/science/ci_24904396/california-drought-whats-causing-it
It's not that California never gets these high-pressure zones blocking its rain, but usually they only last a short time. This current one has lasted 13 straight months! Scientists aren't sure why the ridge is lasting so long, but it is causing some drastic effects. Last year was the driest year in California's recorded history (160 years), and the Sierra Nevada snowpack is 20% of what it normally is. (I'm sure the ski resorts are hurting bad). Reservoirs across the state are only 30-36% full, which means water rationing may occur soon unless they get several big storms.
http://www.mercurynews.com/science/ci_24904396/california-drought-whats-causing-it
This is a picture I took of the East Bay hills (Garin Regional Park) in Hayward, California in December 2013. Usually these hills are covered in new green grass and some blooming wildflowers after winter rains, but not this year. The only reason there are some green trees are because they are evergreen live oaks.