Rattlesnake avalanche was human triggered


The avalanche Friday that swept down Mount Jumbo , destroyed a home inside city limits, and buried three people was human triggered, according to the Missoula Avalanche Center.

Officials with the center said in a press release a snowboarder at the top of the mountain triggered the large slab avalanche.

It crushed a home on Holly Street and buried a young boy and an elderly couple. All three people were found alive and breathing beneath the rubble by rescuers.

Avalanche experts say high winds and continued heavy snowfall have created a high avalanche danger in the mountains surrounding the Missoula Valley and in the foothills areas close to Missoula, as well as Mount Jumbo and Mount Sentinel.

A high avalanche danger means natural avalanches are likely, and human triggered avalanches are very likely. 

Officials with the Missoula Police Department said no mandatory evacuations were in place in the area where the avalanche occurred, but residents were notified by officers going door to door warning them of the danger.

The following is a press release from the Missoula Avalanche Center with more information:


High winds and continued heavy snowfall have created HIGH AVALANCHE DANGER conditions in the Rattlesnake and the southern Swan and Mission Mountains north of Missoula.  This special update also includes the foothills areas close to Missoula as well as Mount Jumbo and Mount Sentinel. The avalanche danger is HIGH on any open slope steeper than 30 degrees.

The avalanche danger in the Bitterroot mountains on wind loaded terrain steeper than 30 degrees is CONSIDERABLE. South facing slopes here also developed a sun crust earlier this week so with east to north winds expect these aspects to get loaded.


Strong east winds and heavy snowfall associated with a blizzard in the Missoula valley have created very dangerous avalanche conditions on Mount Jumbo, Mount  Sentinel and other steep open slopes close to Missoula.  A large slab avalanche was triggered by a snowboarder near the top of Mount Jumbo yesterday afternoon.  The avalanche ran to the valley floor, destroyed two homes and buried 3 people. A large rescue effort consisting of local first response teams, law enforcement, Search and Rescue personnel and at least 100 nearby residents quickly mobilized to assist with search efforts.  All 3 victims were found alive and transported to local hospitals.

The City of Missoula Police and Fire Departments are conducting an investigation  into this tragic event.

Our thoughts are with them and their families hoping for a speedy and full recovery.  Many thanks to everyone involved in this complicated rescue.

Warm temperatures and sun Tuesday and Wednesday created a hard ice crust which is now a perfect bed surface for avalanches. Blizzard conditions in the valley have formed sensitive storm slabs and wind slabs on a variety of aspects. Any open terrain steeper than 30 degrees that has been recently loaded should be avoided.  Many people reported to us Friday that they triggered wind slabs and experienced collapse and fracture propagation in areas loaded by the wind on Mount Sentinel.

It has been many years since Missoula has seen a full-on blizzard with this much snow. High winds are expected again today and will continue to load these low elevation slopes. Please respect these conditions and avoid Mount Jumbo and the steeper slopes of Mount Sentinel for a few days.

The backcountry of the Bitterroot Mountains has not received the heavy snowfall seen in the Rattlesnake or Missoula valley. Mountain winds have been fairly calm until late yesterday when east winds reached the higher elevations. This morning on Point Six, east winds are topping out at 61 mph! The temperature is -21 for a wind chill value in the negative 60 degree range.  I would expect to see high ridgetop winds throughout the Bitterroot today as this arctic air takes hold.

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