It’s called the PDO, the long-term weather pattern sucking the Golden State dry.
Think of it as the Pretty Dry Oscillation – the Pacific Decadal Oscillation. The official name means Pacific (a Pacific Ocean pattern) Decadal (it lasts more than 10 years) Oscillation (it goes back and forth). It is why California is stuck in a drought.
It’s as simple as hot and cold.
Hot air holds more moisture than dry air. Just think of how steamy and sticky the air can feel during a heat wave.
The Pacific Ocean provides moisture for California and the West. When the waters off the West Coast are warm, they heat and moisten air overhead. The prevailing westerly winds blow the ocean air inland and it rains and snows over the cooler lands, particularly over the mountains. When the ocean is cool, the overhead air is cooler and drier.
(Left) The Positive PDO kept the waters off the West Coast warm. (Right) Since 1999, the Negative PDO usually keeps the waters cooler. Source: Browning Newsletter
There is a 50-to-60-year weather pattern, the PDO that determines how hot or cold the West Coast water is. This Pacific Decadal Oscillation used to be positive, keeping the waters relatively warm from 1976 to 1999. Since then, the waters have usually been cooler. This means the ocean airs bring very little moisture inland.
Since 2012, the situation has gotten very bad. Over 80% of California is in drought and there is almost no snow on Southwestern mountains. Nearly 70% of the water California uses comes from melted snow.
No wonder the Governor of California declared a drought emergency. He is listening to weather experts warning him that the next few months may be as dry as this January!
Compare how much snow there was last winter compared to now! Source: NASA
The negative PDO is a trend that usually lasts for 25 to 30 years. Even when the drought ends, the state will be drier than it used to be. Californians are going to have to conserve their water.
There is some good news. Pacific experts are warning that there is a good chance this year will see the arrival of an El Niño by autumn. El Niños usually bring glorious rain and snow to the West. Hang in there, California!
James J. Garriss
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The change in phase or sign of PDO certainly influences climate over longer time scales (annual to decadal). And indeed our physical infrastructure and regulatory systems seem to be designed for that type of climate regime. But, it seems that the switch from drought to atmospheric river then back that appears to be occurring over short time periods (say on the order of weeks to months) may be a new climate regime that seems that modern societies have not evolved with; such rapid changes in climate probably and apparently was not typical over the Holocene. If anything these rapid changes in weather shows us that our present-day resilience to these perturbations in weather is quite non-resilient. Hot dry dusty drought punctuated by high intensity but short lived storms followed by drought is something that our society did not arise from. Likewise, rapid and large changes in the polar jet stream have lead to conditions that some modern-day communities in the US and elsewhere seem ill equipped to handle (e.g., Jan 2014 Atlanta GA).
Hi, Sandy, Thank you for taking the time to write and express your disappointment with the 2014 ÃÛÌÒÁµÈË weather forecast. It's hard to read/hear, but we understand and appreciate that you cared enough to tell us.
I can not imagine how hard it must be for you to read the ÃÛÌÒÁµÈË forecast and not see it "come to life." We appreciate your faith in our predictions and we are sorry that we have not fulfilled your expectations—and ours, which were for rain.
As you may know, the ÃÛÌÒÁµÈË forecasts are made the previous year; the winter forecast was researched and delivered in winter 2013. Evelyn Browning Garriss writes this blog weekly, and so she is describing current events with the benefit of being in the moment.
Our meteorologist is not the only professional prognosticator who did not anticipate this wild swing by the jet stream and so the ensuing results explained above. Although it may be small comfort, the season, the year, is not over. As a saying goes, it only takes a day to change.
Thank you for your belief in what we do (even though I know that faith is diminished...). Loyalty like yours means the world to us.
The ÃÛÌÒÁµÈË Editors
Why with this "PDO" information did "The Old Farmer's ÃÛÌÒÁµÈË" predict wetter than normal January and February 2014 for the California Pacific north west. You had my hopes up because I believed you. Now I have little to no hope at all for us. It's going to be another drought probably worse than the mid 70's. We haven't seen a drop of rain in months. Our lakes are mud puddles; I'm scared to death over this. I feel like we may never see rain again. That's how bleak our outlook is. Now why again did you mis-lead us with the phony prediction of "Wetter than normal Jan. and Feb. 2014"? Just to get our hopes up just to be dashed?
I'm sorry, I'm so scared that I'm lashing out at anybody to blame this frightening situation on. I once believed in you, not now, you'll have to prove yourself again to me in a big way to make me a believer again. Sadly, yours truly, Sandy Wilkins
For Sandy and all,
We have no one to blame for this, but ourselves.
We have been told for years that we must reduce our "carbon footprint" and cut back on our use of petroleum products. Few have listened. Now Mother Nature is making the changes for us, whether we like it or not.
I am an avid gardener and live in California as well. Believe me, I am not pleased with this situation either. In the years ahead, we will have to learn to conserve, reuse and live sustainably or we will all have a very hard time.
