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.
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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!
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The Almanac has historically been very accurate with weather predictions. But to place blame on the staff for the lack of rain is crazy and I personally feel no apologies are necessary.
The Almanac offers weather PREDICTIONS. Information is gathered from multiple sources and then what is offered is (let's face it) and educated guess. Not a certainty, but a possibility.
Please continue with what I consider to be excellent predictions. California is at this moment in the midst of a great storm, so I don't think your Jan-Feb precipitation prediction was wrong, just a few weeks late!
Why are you not warning your subcribers to the influence of weather by the gross dumping of heavy metals and other particulates by jets through GeoEngineering? This is the reasons for such extreme weather patterns. What is your opinion? Thanks!
Thank you. The Almanac staff historically has done a great job. They give the best probabilities.
This current storm won't end the drought but it will offer some much needed relief.
I'm not sure that all El Nino events are similar both in strength ( http://www.pmel.noaa.gov/tao/elnino/faq.html#same ) and their predominate weather effects( http://www.cpc.ncep.noaa.gov/products/precip/CWlink/ENSO/composites/elnino.son.precip.gif ). As the CPC gif shows in the hyperlink above, for autumn in Southern Oregon/Northern California, one landscape can be dry whereas an adjacent landscape can be wet. Of course, these gifs are derived from historical data and thus are a statistical description.
Not all El Ninos are the same. The Japanese have pointed out a Central Pacific El Nino style of event that leaves California dry. (They call it a El Nino Modoki.) Most standard El Ninos, ones that stretch accross the Central and East Pacific, even weak ones, bring some great rains. Even the Japanese at this point see a chance of a normal El Nino.
Agreed. The Modoki version is similar but different but more data is needed to truly discern Modoki as something different. But to the point I was trying to make, for the State of Jefferson in northernmost California (CA), an autumnal El Nino would lead to anomalously low precipitation for those months. Thus I'd be careful for what I wished for.
Too El Nino in California is not the same as El Nino in Nebraska (NE). In both cases, these states are trying to grow food with a finite supply of water but in the face of growing demand for the water from other users. In my estimation, when groundwater supplies are exhausted in CA and NE, irrigation for food will cease, and what now would seem to be a "Black Swan event" will have transpired. If only we knew now what we'll know then. Oh wait. We do. It's just a lack of will, more than money, to prepare for such an outcome. Climate change such as the Arctic Amplification and changes in polar jet stream meanders are a tocsin or early warning of catastrophic change from today's climate to a different climate regime; e.g., wet is getting wetter and dry is getting drier. I've read the Farmers Almanac since I was quite young. I think that prognostication would probably have been quite good from 1950 through 1979 since climate was rather static or stationary back then. But given the recent changes in the various states of the ocean, atmosphere, and land, I would be surprised if anyone could accurately predict future weather based on prior climate. So kudos to you for trying.
Come on El Nino!
PDO may not be entirely causative. Recent Arctic warming has led to changes in the position and strength of the polar jet stream or what has been termed the "Arctic Amplification" (AA). Due to AA, we see a slowing down of and large meanders in the polar jet. Indeed the effects of the AA may be more explanatory of the weather in the US this year.
Good point! There is no single cause of drought. The PDO is a major player in California weather, but not the only one. Historically, when the PDO is negative, the West is more sensitive to a variety of factors and more easily turns dry.
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).
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