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Too early to predict winter snow

Lauren Glendenning
lglendenning@vaildaily.com
Vail, CO Colorado

VAIL, Colorado – After last winter, a long range forecast that is still so long range that it can’t possibly be scientifically accurate is still reason enough for ski town residents to get excited.

An Accuweather map that shows above average snowfall for Colorado this coming winter went viral on social media Wednesday, with posts and shares revealing the excitement many ski and snowboard enthusiasts are feeling when they hear good snow news – even in August.

The worst winter on record is behind us, and now the positive energy is beginning to unfold.

At least everyone knows one thing’s for sure – next winter can’t possibly be worse than last winter. Snow enthusiasts hope that’s the case, at least.

There’s an El Nino weather pattern for 2012-13, meaning there are above-average temperatures in the central Pacific Ocean. The warmer water means warmer air above the Pacific, which affects weather patterns.

But El Nino is just one of many factors in determining snowfall, said Joel Gratz, a meteorologist who runs opensnow.com, a site that forecasts weather for the purposes of directing skiers and riders toward their best powder days.

“The only reason we care about El Nino (right now) is because it’s the only kind of climate weather pattern that we can predict six to nine months in advance,” Gratz said. “However, El Nino is only one thing that controls how much snow we get. Just because we forecast El Nino, that only helps us forecast one piece of the winter.”

El Nino

Long-term weather prediction is fairly simple, Gratz said. Forecasters look at about 50 years or so worth of data and look at winters with similar patterns, such as El Nino or La Nina, and determine that whatever happened during those winters is what generally happens every winter under similar conditions.

“That’s it,” Gratz said. “What I really trust is that if it’s a really strong La Nina, the Pacific Northwest gets a lot of snow. If it’s a really strong El Nino, the southern states get a lot of precipitation. But, if it’s anything in between, it’s really just a crap shoot.”

The 2012-13 winter is certainly something in between, with El Nino appearing to be very weak or possibly moderate, Gratz said.

The National Weather Service’s long-term forecast shows Colorado in the region where above average temperatures are possible November through January. There are equal chances probability for above average or below average precipitation during that time.

Then, the December through February forecast shows equal chances for above average or below average temperatures and precipitation.

Accuweather, based in State College, Pa., notes that no two El Ninos are the same.

“The strength of this phenomenon can mean a great deal for winter weather,” according to the site.

Nobody knows, at least not in August

The Farmer’s Almanac is another source for long range weather predictions. The Almanac started publishing in 1818 and has become a trusted source for weather information, said Managing Editor Sandi Duncan.

The Farmer’s Almanac’s long range forecast comes out Aug. 27 and the predictions will be based on the same formula that’s been used by the Almanac for nearly two centuries.

The formula is a secret and in 196 years there have only been seven forecasters working for the Almanac who know what it is. Duncan said it’s based on a variety of factors including sun spot activity, tidal action of the moon and the position of the planets, among other things.

“We do a pretty good job,” Duncan said. “But it’s a trade secret, like the 21 spices at Kentucky Fried Chicken.”

Last winter was a weak La Nina, and the winter before – Vail’s best snow year on record – was a strong La Nina. And, as Gratz said, the warmer or cooler ocean temperatures are only one part of the very long equation that determines snowfall.

Klaus Wolter, a climate scientist at the University of Colorado Cooperative Institute for Research in Environmental Sciences Climate Diagnostics Center, won’t comment on the upcoming ski season weather before the end of September at the earliest, he said.

Optimism and dreams aside, the fact remains that August is simply too early to tell whether this winter will deliver the goods in large quantities. The fact that meteorologists even make these long range forecasts annoys Gratz – he said it just perpetuates this idea that meteorologists are just blowing smoke. That’s why he likes to stick to forecasting actual storms when they’re seven days, five days or three days out – those are the forecasts that are going to be most accurate.

“The accuracy of long-range forecasts is so low,” Gratz said. “Basically, you could just throw a couple of darts at a dart board.”

Assistant Managing Editor Lauren Glendenning can be reached at 970-748-2983 or lglendenning@vaildaily.com.


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