Snowpack is growing, unstable on slopes
By Ben Graham, Jackson Hole, Wyo.
February 16, 2013
Intermittent storms that blew into the Tetons during the first half of February boosted the snowpack in the mountains around Jackson Hole.
Through the end of last month, total precipitation for the winter was 62 percent of normal. That number jumped to 89 percent by Friday, according to the Snotel websites that collect data throughout the Natural Resources Conservation Service.
“In the last two weeks, we’ve been holding our own,” said Bob Comey, director of the Bridger Teton National Forest Avalanche Center. “The Tetons are doing pretty good, as are the southern parts of Yellowstone.”
The snowpack also has more water content now. The snow-water equivalent rate for the Snake River Basin, which encompasses nearly all of Teton County, was 92 percent of the 30-year median as of Friday.
The snowfall provided relief for skiers and snowboarders, who had to tolerate a dry January. As recently as two weeks ago, the snowpack’s water content was down to 82 percent.
Thumb Divide, next to Yellowstone Lake at an elevation of 7,980 feet above sea level, registered the highest above-normal snowpack reading Friday, with water content at 107 percent of the average. Still, snow depth at the location was down 2 inches compared with last year, from 43 inches to 41 inches.
Other areas that had above-average water content include: Grand Targhee, the East Rim Divide and Two Ocean Plateau.
Granite Creek, south of Jackson, recorded the lowest water rate, with a snowpack 80 percent of normal.
Readings are taken by remote sensors located in the hills around Jackson Hole.
The Snake River Basin and other areas of northwestern Wyoming continue to accrue significantly larger snowpacks than the rest of state.
But the new snow has also increased the avalanche danger around Jackson Hole.
The Greys River area, which includes the Salt River Range, the Snake River Range and the Wyoming Range, had a “high” danger rating on Valentine’s Day. Although that rating was downgraded Friday to “considerable,” Comey said weak, poorly bonded layers, called “faceted” snow, are still a serious issue.
“The problem with faceted snow is that it’s persistent,” he said. “It kind of lurks there and could last for weeks. Now it’s been buried. That’s what’s causing the avalanche hazard in all our areas, but it’s especially pronounced in the Greys River area.”
Comey visited the southern end of the Salt River Range early last week and reported seeing many natural slides.
“Steep slopes are dangerous down there,” he said. “The avalanche danger changes daily.”
Snowpack conditions may continue the current trend for the rest of the month.
“I don’t foresee any long periods of drought like we experienced in January,” said meteorologist Jim Woodmency, who runs MountainWeather.com. “I think we’re going to see regular snow storms coming through with breaks in between.”