Winter forecast looks dry

SUMMIT COUNTY — The weather year, which starts Oct. 1, began with a slight moisture surplus, with above-average snowfall in Dillon and Breckenridge. The beginning of the season is timed to coincide with the start of the winter snowfall season.

Both National Weather Service observation sites reported healthy doses of autumn snow, with 12 inches at Dillon and 22.6 inches in Breckenridge, about 30 percent above the historic average.

But this year’s monthly totals don’t come close to comparing to the big dumps of October 2006, when more than three feet fell in Breckenridge, making it the third-wettest October on record, going back into the late 1800s.

Breckenridge weather watcher Rick Bly has been able to link October precipitation with season-long trends showing that, if October snowfall is above-normal, there’s a better than average chance the rest of winter will also bring good snow.

But that statistic may be trumped by the late emergence of La Niña conditions, when sea surface temperatures in the eastern Pacific are cooler than normal. This periodic cycle in ocean temperatures helps drive the storm track.

And for now, that pattern is not looking good for Colorado, said Klaus Wolter, who specializes in climate diagnostics with the National Oceanic and Atmospheric Administration.

Wolter said his record of forecasting winter snowfall for the southern Rockies during La Niña conditions is not all that reliable. But he’s pessimistic about the current storm track, which is setting up too far north to bring much snow to Colorado, at least for the next couple of weeks.

“This year is looking very dry ... we may be sliding toward drought, but not as bad as 2002,” Wolter said. “I just don’t like the way the storm track is setting up.”

Wolter said there is chance for some decent storms beginning late November through late December.

“We might catch up a bit, but it’s January through March that I’m most worried about,” Wolter said. “And the next two weeks are looking grim.”

Often, La Niña brings heavy snow to the Pacific Northwest and drought conditions to the Southwest, as well as eastern Colorado. Impacts to snow in the mountain region have been more difficult to pinpoint, but Wolter said the late onset of this La Niña may be one of the factors pointing to a dry winter.

By contrast, last season’s heavy early season snowfall was at least partially driven by El Niño conditions, with warmer-than-usual eastern Pacific ocean temps pumping copious moisture into Colorado.

<b>Local impact</b>
Locally, reservoir levels and streamflows have been holding their own, said Scott Hummer, the State Engineer’s water commissioner for the Blue River Basin. Dillon Reservoir is exceptionally full for this time of year, and most streams are flowing near historic means, Hummer said.

That means snowmakers at Summit County resorts have been able to take their full allotments, at least when temperatures permit.

Keystone, for example, used 28.3 acre-feet of water for snowmaking during October, while Arapahoe Basin drew 19.65 acre-feet out of the North Fork to produce artificial white stuff.

Temperature records from the Dillon site show a continued trend toward warmer night temperatures. The average low for October was 25.3 degrees, more than five degrees above the historic average.

The average high for October 2007 was 56.7 degrees (historic average, 55.3 degrees). Temperatures went to 60 degrees or above 15 times, and climbed above freezing every single day except Oct. 22, when the daytime high topped out at 30 degrees.

Nighttime lows dipped into the teens only once, lingering in the 20s and 30s the rest of the time.

The forecast for the next few days calls for continued sunny and warm, with chance for some flakes this weekend.

<i>Bob Berwyn can be reached at (970) 331-5996, or at bberwyn@summitdaily.com.</i>