Note: this bulletin is published in the pm and effective for the following day. Be alert to differences in the forecast and actual snowfall amounts and weather activity overnight.
Backcountry Avalanche Danger Rating
Current Avalanche Problems
Quite a few observations coming in today of both human triggered and natural slab avalanches, up to size 2.0, around the Niseko area. Several storm slab releases reported on West aspects, across a range of elevation bands. Naturally triggered size 1.0 around 500m and a skier triggered size 1.0 around 1,200m. There is also a report of a skier triggered, wind slab avalanche that caught and partially buried at least one member of the party. Today is a great reminder… statistically, most avalanche accidents occur on days when the hazard rating is in the MODERATE to CONSIDERABLE zone.
This is exactly where we will be tomorrow. Let’s look at the wording associated with the CONSIDERABLE hazard rating. The travel advice and likelihood are pretty spot on for what I expect tomorrow:
‘Dangerous snowpack conditions. Careful snowpack evaluation, cautious route finding, and conservative decision making are essential. Natural avalanches are possible, and human triggered avalanches are likely.’
The size and distribution, however, is a bit exaggerated for what we can likely expect:
‘small avalanches in many areas, or large avalanches in specific areas, or very large avalanches in isolated areas.’
However, the size and distribution wording for the MODERATE hazard rating is probably more in line with our current conditions:
‘small avalanched in specific areas, or large avalanches in isolated areas.’
So, are we at MODERATE or CONSIDERABLE? Quite frankly, it’s a game of semantics at this point. There are several algorithms that I use to calculate a danger rating, including matching up my expectations with the wording in the danger scale. I walk through all of these methods every day, compare the results, and ultimately make a judgement call on what seems most appropriate. Bottom line is, avalanche activity was occurring today. Both due to wind slabs (on higher, exposed slopes) and storm slabs (in more sheltered areas). Both winds and fresh snowfall (stresses on the snowpack) will likely be continuing overnight and throughout the day. Storm slabs may begin to settle out, or they may become even less stable. Wind slabs will remain unstable.
Please familiarize yourself with the danger rating scale. You can find some great information on it here
As a local guide and avalanche professional, I have chosen to share this hazard assessment in the interest of encouraging better information sharing within the local community. This avalanche bulletin is to be used at your own risk and is based on very limited data gathered by myself and other guides working for Japan Powder Connection. Please use this information in addition to other resources and take responsibility for your own actions in the backcountry. Also, please respect and abide by all Niseko Area Rules. This information applies only to backcountry areas accessed externally from area resorts. This information is published the evening before and in effect for the following day.
As always, remember that making good decisions in the backcountry takes years of practice and experience. Having the gear is a small part of the equation. Take an avalanche safety course and hire a properly trained guide so you don’t learn the hard way!
Japan Powder Connection - Professional Backcountry Guides and Instructors
Niseko Avalanche Information - Niseko’s avalanche information page. Not a ‘bulletin’ by Western standards, but Shinyasan has been doing this for 20+ years and knows these mountains far better than myself.
Snow-Forecast - Niseko Area Weather Forecast
Niseko Now - Local Weather and Conditions Summary