La Nina, snow and your Mammoth Mountain holiday

By Dean Kuipers

Dec. 13, 2011 12 AM PT

Yes, the mountains of Southern California got a little snow, but the state’s biggest snow hill, Mammoth Mountain, is still feeling pretty bony. Fun, but as much fun as man-made snow can be. And we have that lil’ La Niña to blame.

But wait, last year was also a La Niña year, and Mammoth got blasted with more than 668 inches of snow, including epic pre-Christmas dumps that made for a great holiday season. This year, according to the Mammoth Mountain website, we’re sitting at 49 inches. What gives?

“Last year was not a normal La Niña year,” says Howard Sheckter, owner of MammothWeather.com and for 32 years a familiar forecaster to Mammoth skiers, who know him as the “Dweeb.”

“Typically, in a La Nina year, it becomes drier as it moves south,” he said. “The weather is up in the Pacific Northwest, it’s considered above normal temperatures from Northern California up through Washington and Oregon and into British Columbia. And when you get down to the Central California, you’re on the dividing line so it’s equal chances of a normal winter. When you get into Southern California, it’s usually drier than normal.”

A La Niña year happens when Pacific Ocean surface water temperatures north and south of the equator are colder than average. This year is a moderate La Niña, with temps about 1 degree Celsius colder than average. An El Niño year is the opposite, when the water temperatures are higher than normal, making for wetter winters.

So far, then, we’re having a typical La Niña, which should mean average snow, or around 340 inches. But Sheckter says we might not expect that to start showing up until the end of January.

Why? A weather pattern or “teleconnection” called the Arctic Oscillation is in a positive phase, which has high pressure ridges parked off the Central Coast and splits the fronts that come through, sending the energy north and south, missing Mammoth. Bummer for the snowpack.

Sheckter says he expects that oscillation to normalize or flip, however, near the end of January and for the big snow to hit then.

“I think the further into January we go, the better the chance that the pattern will change and become wetter, and as we get into February, especially the first half of March, it could be very wet here in Mammoth. That would be my best guess.”

You heard him use the word “guess.”

More fun with weather soon!

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-- Dean Kuipers