B R ID GER- T ETON N AT ION AL FOREST
Wade McKoy / FPI / Storm Show Studios
A
AVALANCHE CENTER
By Lisa Van Sciver
t 4 a.m. on Thursday, February 9, 2017, Chris McCollister drove past 17 downed power line poles, heading to the Bridger-Teton National Forest Avalanche Center office at the Jackson Hole Mountain Resort. Fierce winds had snapped or toppled the steel structures sometime Tuesday, killing power to Teton Village, closing the Jackson Hole Mountain Resort, and shuttering all access roads into the valley. Computerized weather models and forecasts at his office confirmed that an already epic storm was intensifying. McCollister compiled temperatures, winds, estimated precipitation and relative humidity for the previous 24 hours from remote weather stations. His general avalanche advisory was a blunt warning: “Very dangerous avalanche conditions exist and all avalanche terrain should be avoided today.” The advisory, as usual, would cover three major zones: Teton, Continental Divide/Togwotee Pass, and Southwest Trails/Grey’s River areas. Increasing temperatures, along with constant rain and snow, would likely cause natural wind slab and spawn wet avalanches. McCollister pegged the day’s hazard rating at “high” and “extreme” in all three areas. He also attached the previous day’s encounter with nature by some recreationists, two snowmobilers who had been caught in a slide on Togwotee Pass. Both somehow were uninjured. After completing his work with the forest service, McCollister donned his ski patrol jacket and joined patrol forecaster Mike Rheam, to compile the ski area forecast. Fifty-plus ski patrollers had already boarded the tram, still running on diesel backup. As the car’s doors
Snowboarder Ryan Vanlanen escapes an avalanche at The Cave, a backcountry feature popular with film crews. Left: Lisa Van Sciver, Jackson Hole ski patroller
Wade McKoy photos
Below: Unprecedented winds buckled 17 steel power poles, causing a week-long blackout in Teton Village. closed a chorus greeted him, “Good morning, Chris.” McCollister ran through the stats: “It is thirty at R. Bowl, thirty at Raymer, twenty-nine at mid and thirty-two at the base.” He continued with the compiled 24-hour high and low temperatures, winds, snowfall, and the total to date in Rendezvous Bowl—412 inches. Avalanche-hazard reduction leader Kirk Speckals followed up with the morning plan to run through avalanche mitigation and manage the hazard, so the ski area could reopen once power was restored. Inside Corbet’s Cabin patrollers loaded their packs with explosives. McCollister headed out the door on Route 5 with four “routies.” They skied down to the East Ridge, where he deployed a four-pound charge. Ninety seconds later, the explosion triggered an avalanche, a four-foot crown in its wake. The group continued down the mountain, carefully tossing explosives to trigger avalanches. On McCollister’s secw w w. j h s k i e r. n e t
ond lap off the tram, he skied down to the Rendezvous Bowl snow study plot. There he used his density tube to measure and record the snow and water on the 24-hour board. He also noted 131 inches on the total-season snow stake. At around the 8,000-foot level, the falling snow had turned to rain. At the BTNF-Avalanche Center, forecaster McCollister shed his soaked patrol jacket to log explosive-triggered avalanches of both the ski patrol and the Wyoming Department of Transportation. He then sorted through the observations of natural and human triggered avalanches. McCollister’s heart sank when he was notified of a snowmobiler fatality in McCoy Creek. Outside, the snow and rain continued, and so did McCollister’s work. At 5 p.m. he wove the day’s events into the Western Wyoming Evening Forecast: “Between yesterday afternoon and 9 a.m. this morning, 15 inches of snow containing 2.3 inches of moisture has fallen at the Rendezvous Bowl study plot.” At 7 p.m., McCollister left the office and headed to his car. The prodigious valley snowpack was melting; he wondered how the backcountry hazard would increase and how the snow would react. McCollister could only hope that recreationists would take note of the avalanche warning running through 1 p.m. the following day. At some point, likely on Sunday, McCollister would visit some backcountry weather stations; tonight, though, he would visit them remotely. Lisa Van Sciver is a Jackson Hole ski patroller and assists with the Bridger-Teton Avalanche Center operations. 2018
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