By Tom Jackson
If you heliskied last season, you know, so skip ahead to the quote from the leading expert.
2011 was epic, thanks to La Niña. It was a big one, so chances are it will be a two-year event!
If you need a primer, it’s a weather pattern resulting in heavy precipitation and colder temperatures for North America. Cycles happen over a period of years, essentially opposite of El Nino. Both are the result of changes in temperature, pressure and ocean currents.
Canadian Heliskiing was biblical last season, as we predicted last year, see El Niño: Spanish for POW! We also wrote in Global Warming Takes a Season Off, “The strongest La Niña since 1955. No need to panic, as long as you will be putting on your snorkel the next time this happens – 2065.” And we were right.
Meteorologist Joel Gratz correctly forecasted this big La Niña in October 2010. Joel runs a cool powder forecasting site, ColoradoPowderForecast.com out of Boulder, Colorado. My favorite feature is the Snow Alarm, where you can sort resorts by new snow….but I digress. “In general, cooler water in the central Pacific Ocean (i.e. La Niña) 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. “
You will not be tested on this information from the NOAA website: “El Niño/Southern Oscillation (ENSO) is the most important coupled ocean-atmosphere phenomenon to cause global climate variability on interannual time scales. Here (NOAA) we attempt to monitor ENSO by basing the Multivariate ENSO Index (MEI) on the six main observed variables over the tropical Pacific. These six variables are: sea-level pressure (P), zonal (U) and meridional (V) components of the surface wind, sea surface temperature (S), surface air temperature (A), and total cloudiness fraction of the sky (C). These observations have been collected and published in ICOADS for many years. The MEI is computed separately for each of twelve sliding bi-monthly seasons (Dec/Jan, Jan/Feb,…, Nov/Dec). After spatially filtering the individual fields into clusters (Wolter, 1987), the MEI is calculated as the first unrotated Principal Component (PC) of all six observed fields combined. This is accomplished by normalizing the total variance of each field first, and then performing the extraction of the first PC on the co-variance matrix of the combined fields (Wolter and Timlin, 1993). In order to keep the MEI comparable, all seasonal values are standardized with respect to each season and to the 1950-93 reference period.”
The index used to predict La Niña’s (multivariate ENSO) looks good. Negative readings (blue) and rapid transitions are good for powder:
Heliskiing Canada looks great again for 2012. It turns out that the big La Niña events, like the one that dumped on North America in 2011, often span two heliski seasons.
How does 2010 rank? According to the National Oceanic and Atmospheric Administration (NOAA), “The recent La Niña event had been classified as strong (top 6 rankings since 1950) for nine months, or from July-August 2010 through March-April, tied with 1975-76 for 2nd place in terms of strong duration, and only behind 1955-56 (15 months).”
Check out this graph (negative is good) and note that the major La Niña’s extended for two years / heliski seasons: 45-46, 49-51, 64-66, 70-72, 88-90 and 2011- (2012?).
“Once La Niña gets as big as this one, odds are higher than 50% that it ends up being a two-year event,” explains Klaus Wolter, an expert in El Nino/La Niña at NOAA . So far, so good. According to Mr. Wolter, “Big La Niña events have a strong tendency to re-emerge after ‘taking time off’ during northern hemispheric summer, as last seen in 2008. I believe the odds for a two-year event remain well above 50% “.
Time to get you buddies together and reserve your seats in the chopper!