Avalanche Bulletin
更新日時: 2025/01/31 05:30
Hakuba
Alpine Fair
Treeline Fair
Below Treeline Good
信頼度：○ good □ Fair △ Low
Travel and Terrain Advice
Even if snowfall weakens or stops, avalanche danger remains high. The structure is composed of relatively dense snow that has been moved by the wind and placed on top of the previously new snow. The new snow has not yet gained sufficient strength and has not yet well bonded with the Melt-Freeze crusts that lie beneath the storm snow. Even at lower elevations, there is potential for large avalanches on the large open slopes to the south. Inexperienced groups are still recommended to enjoy the ski area today.
Avalanche Problem
ウインドスラブ Wind slab
Be alert for wind slabs formed by northerly winds. A hard snow surface does not mean safety; the storm snow has not yet gained sufficient strength. Therefore, your triggering of a relatively small windslab could trigger the breakup of the underlying weak layer of storm snow, which could then expand in size.
ストームスラブ Storm slab
In terrain with low wind influence, fresh snow can be very deep. Consider your terrain selection in light of the fact that even a small avalanche can bury you deep in the situation.
概要
Avalanche
Yesterday (30th), numerous storm slab avalanches were reported in the morning management of ski resorts. And some ski areas have suspended lift operations because the avalanche danger is so high. There was also an avalanche incident on a well-defined avalanche path below treeline. Size 2-2.5, Storm slab, Elevation 1,850 m, SE slope. While Skier was passing through the avalanche path at intervals, a spontaneous avalanche occurred at the top and involved two people, one partially buried and one unburied. Neither was injured. Details are currently being confirmed.
Snowpack
Snowfall since January 29th has weakened, but winds became very strong around noon on January 30th. Maximum wind speeds of 30 m/s were recorded on the main ridge. Therefore, this heavy snowfall has been redistributed by the strong northerly winds. A layer within the new snow that has not yet fully intensified and is not bonding well with the underlying Melt-Freeze crust was observed yesterday in the below treeline.
Weather
The Japan Meteorological Agency is forecasting northerly winds, cloudy skies, and snow in places, with a daytime high of 3 °C (418 m elevation) for northern Nagano Prefecture. At 703 m elevation (Hakuba), the temperature is -3.5 °C (as of 5:00 a.m.), with no new snowfall in the past 12 hours. The Nagano District Meteorological Observatory is forecasting 20 cm of snowfall for northern Nagano Prefecture in the next 24 hours until 6:00 a.m. on February 1, at 4:39 a.m. on February 31. At the main ridge (elevation 2,400 m), the temperature is -15°C with northerly winds averaging 16-17 m/s and maxing out at 22-25 m/s.
