First, a note of full disclosure: I am very much rooting for another La Niña season this winter. I am a skier and I live in the Pacific Northwest, the corner of the country that perhaps benefits most from La Niña's touch.
Last season's La Niña was enjoyable from its record-breaking start to its lingering finish (with the exception of a rainy January). National snowfall totals were up 27 percent and heaping powder days crashed into the next everywhere from Tahoe to Utah. Why would I not wish for another winter like that?
All of which is to say when the National Weather Service's Climate Prediction Center recently issued a La Niña watch for the 2011-12 season, I was overjoyed at the thought of a repeat. But I was also skeptical: La Niña rarely graces us with her presence two years in a row. We last had back-to-back La Niñas in the winters of 1998-99 and 1999-2000, and according to reports from the National Oceanic and Atmospheric Administration, it also happened (weakly) in the early 1980s and (more strongly) in the 1970s. But that's it.
Here's what the report from the National Weather Service, issued August 4, said about this winter: "ENSO-neutral is expected to continue into the Northern Hemisphere fall 2011, with ENSO-neutral or La Niña equally likely thereafter."
"Equally likely." Which is a nice way of saying, "We're not entirely sure." Yet, after that was released, headlines everywhere from UnofficialNetworks.com to the New York Times blared about the potential for another cool winter. Skiers everywhere started their snow dances early.
But not so fast. Seven other global prediction models from weather organizations outside the U.S. -- including the Australian Bureau of Meteorology, the UK Met Office, the Japan Met Agency and the Korean Met Administration -- are all calling for an ENSO neutral winter, meaning not La Niña or El Niño.
The U.S.'s weather agency is currently the only global model calling for a cool winter. How could this be? And which model should be trust? I called some experts to find out.
"With any kind of weather forecasting, there are different models," said Robert Henson, a Colorado-based meteorologist and editor with the University of Atmospheric Research. "They all use the same basic equations of physics, but each model characterizes some pieces of the puzzle differently. If you have seven models saying neutral and one saying cool, you'd probably look at them and say it's going to be neutral. But anything can happen in any given year."
Jim Steenburgh, a PhD in Atmospheric Sciences at the University of Utah, wrote in an email: "No single model is clearly superior to the others. All we can say is that we expect something between ENSO-neutral and La Niña." And when I asked Steenburgh what his hunch was, he responded, "I don't really have a hunch, except that a bad year in Utah is better
than a good year just about anywhere else. Thus, I'm counting on getting in some good powder days."
My take? It's still August. We should just wait and see. But I'm crossing my fingers that whatever type of winter this is, it's a long, cold and snowy one.