El Niño 2015-2016

From Daniel Swain, of Weather West. For niffty charts and graphs and all manner of things, see his blog “Weather West” – link in the right column.

“Early 2015 brought similar news, with several new bursts of westerly winds and corresponding model forecasts of a building El Niño. This time, however, the anomalous westerly winds did not abate. The East Pacific had already built up considerable tropical and extratropical warmth during the “non-El Niño” of 2014, and additional heat quickly accumulated through the spring and early summer months of 2015. Much unlike 2014, ocean-atmosphere model forecasts continued to grow more emphatic regarding the potential for a very significant El Niño event by late summer. And this time, they were right: warmth the eastern tropical Pacific has recently reached values only seen previously during the strongest El Niño on record in 1997-1998. The atmosphere, too, has gotten its act together this time around—and is exhibiting a more strongly El Niño-like circulation pattern than has ever been observed previously during the summer months. Nearly every record that exists regarding tropical cyclones in the tropical Pacific has been broken over the past six months—and as of this writing, 3 major hurricanes were churning simultaneously over the central and eastern Pacific for the first time in recorded history. In fact, the combination of a powerful El Niño event and the sudden re-emergence of accumulated heat from the tropical West Pacific has created unprecedented warmth over a vast expanse of ocean, stretching thousands of miles from coastal Peru to the Gulf of Alaska.”

“It’s hard to imagine a more powerful predictive signal for California winter precipitation than the occurrence of a very strong El Niño event. Weak to moderate El Niño events can have highly variable effects in California, and are in most cases poor predictors of how much precipitation might fall in the Golden State. But the big events are a whole different ballgame—and the presence of a powerful El Niño in the tropical Pacific is the single most useful piece of information we have regarding what might take place in the months to come.

While even a record-strength El Niño in the tropical Pacific does not mean that California will experience record rains this winter—since there are always other factors at play—it does strongly shift the odds in favor of a wet winter. This not only fits with conceptual models regarding the atmospheric effects of El Niño, but is also strongly supported by model predictions. While the models do disagree upon the details, there is a very clear signal toward a classic “El Niño” winter dipole along the West Coast of North America, with much below-average precipitation in the Pacific Northwest and British Columbia and much above-average precipitation over essentially all of California from the Oregon border to Baja California.”

There you have it. Stocking up on extra food, dog food, wine, propane, and gas. Am I forgetting anything?