High pressure weather system keeping Vail ‘abnormally dry,’ with not much snow in immediate forecast | VailDaily.com

High pressure weather system keeping Vail ‘abnormally dry,’ with not much snow in immediate forecast

Much of Western Colorado, below left, is conditions classified as either "abnormally dry" (yellow) or "moderate drought" (tan). A persistent high pressure system in the Intermountain West is keeping snow-making systems from reaching the Colorado Rockies.

EAGLE COUNTY — Snowfall is variable in the Rockies, with better and worse early-season snow. This season so far is not good.

According to data from National Water and Climate Center's Snotel snow-measurement sites around the area, snowfall is behind the 30-year median snowfall for this time in the season. In some cases, that snowfall is way behind the median. On Vail Mountain, the snowpack as of Monday, Dec. 11, was only 25 percent of the 30-year median. That's due in part to changes around the site — which used to be in an aspen grove but is now in an open area. But the fact of the matter is there simply isn't much snow right now.

The U.S. Drought Monitor describes much of western Colorado as either "abnormally dry" or in "moderate drought." Most of Eagle County is abnormally dry.

The region also seems to have reverted back to warmer daytime temperatures.

The National Weather Service forecast for the town of Vail through Sunday, Dec. 17, is for daytime temperatures ranging from the 30s to the low 40s. Making snow at Vail and Beaver Creek requires temperatures no higher than the mid-20s, with low relative humidity. Last week, cooler daytime temperatures allowed snowmaking crews to operate almost around the clock.

And, despite frequent car washes or Native American snow dances, the near-term prospects aren't great for snow in great quantities.

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Matt Aleksa, a forecaster at the Grand Junction office of the National Weather Service, said a ridge of high pressure has been dominating the weather over much of the Intermountain West region for several weeks. High pressure in the atmosphere generally turns away the low-pressure systems that tend to bring moisture. In the case of this ridge, it's been bouncing systems to the north. Those systems bypass the Colorado Rockies and then dive south with the current flow of the jet stream. That's why Austin, Texas, last week got about as much snow as Vail did.

Aleksa said a small disturbance might bring some snow to the Vail area by Saturday, Dec. 16. But, he added, it looks as if the high pressure ridge may rebuild.

"It's going to take a bigger low pressure system that can move through that's strong enough to weaken the high (pressure) and shift it," Aleksa said.

With high pressure dominating in this part of North America, Aleksa said that's shunting away possible impacts from a La Nina effect in the Pacific Ocean.

Usually, La Nina patterns — cooler-than-average ocean water temperatures in a region about 1,000 miles west of South America — bring better snowfall to the northern Rockies, leaving the southern mountains drier than usual.

Despite the current dry spell, the most recent long-range map from the National Oceanographic and Atmospheric Administration still calls for about an equal chance of above- or below-average snowfall for this part of the Rockies, along with slightly warmer temperatures.

Weather forecasters don't make predictions past about seven days with any degree of confidence.

Still, Aleksa said some models show the high pressure system shifting by the "later half of December." But, he added, those models shift virtually every day.

At the Open Snow website, Colorado forecaster Joel Gratz is calling for the chance of snow starting Saturday, Dec. 16, and lasting for two or three days.

That system could bring several inches or a dusting, Gratz wrote. Keep washing the cars. And, if you know an ancient snow dance, do it.

Vail Daily Business Editor Scott Miller can be reached at 970-748-2930, smiller@vaildaily.com or @scottnmiller.

By the numbers

25 percent: Percentage of 30-year median snowfall on Vail Mountain.

55 percent: Percentage of 30-year median snowfall at Copper Mountain, the closest measurement site to the headwaters of Gore Creek.

98 percent: Percentage of 30-year median snowfall at Fremont Pass, near the headwaters of the Eagle River.

Source: Numbers were reported Monday, Dec. 11, by snow-measurement equipment operated by the U.S. Department of Agriculture and provided by the Eagle River Water & Sanitation District.