Special Update for Mt Jumbo and Foothills Areas
Good morning, this is Steve Karkanen from the West Central Montana Avalanche Center. This special update is being provided for areas of Missoula Conservation District lands including Mt. Jumbo. Mt. Sentinel, and other low elevation open space where heavy snow has accumulated on steep open terrain.
On Sunday March 2, avalanche specialists from the West Central Montana Avalanche Center visited the starting zone of the Mount Jumbo avalanche to document the snowpack structure.
Their findings indicate that a weak snowpack structure is still present on Mount Jumbo and that the avalanche danger is CONSIDERABLE or Level 3.
Natural avalanches are possible, human triggered avalanches are likely. Steep, wind loaded terrain and areas where there are terrain traps, such as gullies, are dangerous. Avoid slopes steeper than 30 degrees.
Avalanche specialists noted isolated areas of collapsing and whoompfhing of the snow while they traveled to the site. This is an obvious clue of unstable snow conditions.
Sensitive wind slabs are sitting on an ice crust (see profile) that formed during warm sunny weather last Tuesday and Wednesday. The interface of the new snow and ice is weak and it does not take much force or weight to produce failure.
Heavy new snow or rain will rapidly increase the avalanche danger. Areas where gullies reach the valley floor should be avoided if this occurs.
Although currently weak, the snow is slowly gaining strength. Moderate temperatures will help diminish the danger.
Avalanche Specialists are working with the City of Missoula to assist with snow safety assessments and avalanche information updates. The City of Missoula has closed public access to these areas, please respect this closure.
The Missoula City Police Department is continuing their investigation of this accident and we will provide more details as information becomes available.
This information does not apply to backcountry areas. The regular backcountry avalanche advisory will be updated by Dudley Improta Tuesday morning.