Hakuba Backcountry Advisory – 10th Mar 2011

Yesterdays snow as it began to fall was of a high density and combined with mild air temperatures and warm melt grains at the surface of snow at low elevation this new storm interface will tend to bond and freeze together. The snow over night was of lower density and of a cooler temperature than the warm dense snow of yesterday and will not be bonding well to the snow below it. This light snow is known as Kami Yuki and snow fall in the Hakuba area may be deeper in the southern mountains than the Otari Mountains in the North. This will change later today as winds and snow change to the general Winter Pattern of snow fall and will begin to fall at greater intensity from the North West. The temperatures will also no doubt rise durring the day and cause a Density Sandwich with the light low density Kami Yuki between the layers of higher density snow above and below this light snow.

Remember that at higher elevation the wet melt grains will have frozen into a crust pre the recent storm snow and will also have a week bond at this melt crust / storm snow interface.

Expect stability to decrease during the storm. Expect loose avalanches to run easily fast and far. Take due care in steep terrain and in open areas above creeks tight trees and cliffs. In general avoid areas above terrain traps.

The new snow should begin to settle and bond over the next couple of days but will be very unstable while the snow continues to fall.


Take due caution in the Alpine and stay to supported terrain and watch for hollow sounds / wumpfing and cracking from your skis that indicate wind slab and instability. The storm snow may be over riding past wind slab and thus avalanches in the alpine can be expected to be of greater size and destructive force.