First, let me reiterate that I HATE long-term forecasts. Beyond about seven days, weather forecasts are just about meaningless. So why, in April 2011, am I going to talk about the weather seven to twelve months from now? Because La Nina might be back for a second showing. If you ski in the northern half of the U.S., this might seriously pique your interest.
Back in October of 2010, I wrote an article about “What La Nina Means for Snowfall”. In general, cooler water in the central Pacific Ocean (i.e. La Nina) can stir the atmosphere in such a way to produce above average snowfall for the northern half of the United States and many areas of Canada. Looking back at this season’s snowfall, that general forecast came true. In short, La Nina was kind to most ski slopes and faceshots were plentiful this winter.
As this amazing season winds down, the greedy powder skier (e.g. You) is probably wondering if next season can even come close to this season in terms of snow. The answer? Better than a 50% chance. That might not sound like a good forecast, but actually it’s about as good as it gets when we’re looking seven to twelve months into the future.
Klaus Wolter, an expert in El Nino/La Nina, recently commented that, “Once La Niña gets as big as this one, odds are higher than 50% that it ends up being a two-year event, even if it weakens (or disappears) during the summer.”
This season’s La Nina was the strongest we’ve seen in the last 35 years, and is in the top 6 since 1950. So in layman’s terms, once a La Nina gets this strong for a winter season, while it’s likely to weaken over the summer, chances are good that it will strengthen once again next season. In super layman’s terms, this means that if you enjoyed this season’s snow, there’s better than a 50/50 chance that next season will be equally as fun.
The thick blue line on the graphic shows Pacific Ocean temperatures (above the “0” line roughly means El Nino, and below the “0” line roughly means La Nina) from July 2009 through April 2011. The other colored lines show ocean temperatures from similar seasons over the past 50 years. History is a powerful tool, since many of the previous seasons with an El Nino followed by a La Nina tend to keep a La Nina for a second season. So if you like powder, perhaps history isn’t such a boring subject after all. Here’s to next season…
Thanks for reading all of my weather geekdom this season, and have a great summer. Just watch out for lightning; it’s kinda a buzz kill.
The dark blue line shows this season’s water temperatures, and the “0” on the left axis indicates water temperatures in the central Pacific Ocean that are normal. Where the blue line is above “0”, water temperatures were above normal, which equals an El Nino (last season). Where the blue line is below “0”, water temperatures were below normal, which equals a La Nina (this season). The other colored lines show similar time periods in the last 50 years where a La Nina followed an El Nino. During many of these seasons, the La Nina persisted for two seasons. Image courtesy of The International Research Institute for Climate and Society at Columbia University.
Meteorologist Joel Gratz is the creator of http://www.ColoradoPowderForecast.com and is based in Boulder, CO.