California is in a horrible drought. Everyone was relieved last winter when they were told that there might be an El Niño. El Niños, warm conditions in the Tropical Pacific, bring heavy rainfall to California. Right?
A Standard El Niño would bring rainfall to California. Source: The Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
Errrrr—not always. Sometimes you get “peek-a-boo” El Niños! Now it rains, now it’s dry.
According to global satellite observations, we have had El Niño warmth in the Pacific since autumn. California saw good rain in December, drought in January, February, and March. There is some West Coast rainfall now but at this time of year, the rain usually is in the Pacific Northwest and only the northern fringe of the state gets rainfall.
A cool pool of water made this winter’s condition more like a Central Pacific El Niño. Source: The Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
Here’s what is happening. There are a lot of cycles in the oceans, including several in the Pacific. One of these are cold MJOs (Madden-Julian Oscillations), small pools of cool water that race through tropical waters. They can really mess up the large warm El Niño. If they are in the wrong place, they keep El Niño from bringing tropical rain to California.
This winter’s El Niño was messed up. It started to bring rainfall, then a cool MJO moved into the wrong place. When the cool water is off the coast of South America, the El Niño becomes a Central El Niño or what the Japanese call an El Niño Modoki. It stops the rain in California and brings hot temperatures to evaporate what little water there is. It also shifts global wind patterns encouraging a high pressure to form in the North Pacific that blocks cool northern rains.
(Left) US rainfall during a standard El Niños (Right) US rainfall during a Central Pacific El Niño/El Niño Modoki Source: The Browning Newsletter, based on information from The Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) predicted Central El Niño conditions starting at the beginning of this year. They were right. The standard conditions shifted to the Central Pacific conditions. The rains stopped falling in California.
It was peek-a-boo El Niño conditions. It created peek-a-boo rainfall in California. It’s not a nice game.