Avalanche Bulletin
更新日時: 2025/02/12 05:30
Hakuba
Alpine Fair
Treeline Fair
Below Treeline Good
信頼度：○ good □ Fair △ Low
Travel and Terrain Advice
Watch out for wind slabs in alpine and treeline. Yesterday's strong winds have formed in many different places. Be alert for slabs in places where avalanches are more likely to occur, such as convex or unsupported terrain. Also, remember that on steep south-facing slopes that receive a lot of solar radiation, the slab may change in hardness during the day, making it more prone to triggering. A hard snow surface does not mean safety. Snow is well cooled by radiative cooling. If you choose simple terrain, free from the influence of wind, you will enjoy great powder snow. Keep good communication with your companions and make good use of the safe zones. Have a good day.
Avalanche Problem
ウインドスラブ Wind slab
If there is a snow plume during the action, still consider that a new slab is being created. Remember that the slab's hardness and triggering sensitivity changes during the day.
ストームスラブ Storm slab
Beware of very steep slopes affected by sunny slopes where the upper layer of snowpack has strong slab characteristics
概要
Avalanche
Yesterday (11th), several size 2-3 avalanches were observed in Alpine, likely during stormy weather. Several wind slab avalanches of size 1-1.5 were also reported. These avalanches were new wind slabs triggered by skiers.
Snowpack
The stormy weather that began on February 4 ended completely yesterday afternoon. The lower layers of the storm snow have been sintering steadily, and the upper snowpack is composed of 30-40 cm of new snow that fell in the past two days. This snow near the surface layer has been moved by yesterday's strong northwest wind, forming a wind slab on the downwind side. The wind is particularly noticeable in the alpine and treeline areas. Today's warming temperatures and warm southerly winds will help to resolve the instability of the storm snow.
Weather
The Japan Meteorological Agency is forecasting southerly winds, clear, then cloudy, rain or snow at night, and daytime highs of 7 °C (418 m elevation) for northern Nagano Prefecture. At Amedas Hakuba (elevation 703 m), the temperature is -3.4 °C (as of 5:00 pm), with no new snowfall in the past 12 hours. The Nagano District Meteorological Observatory forecast 30 mm precipitation (5 cm snowfall) for northern Nagano Prefecture at 4:19 a.m. on February 12 for the 24-hour period ending at 6:00 a.m. on February 13. At the main ridge line (elevation 2,400 m), the temperature is -6°C with northerly winds averaging 15-16 m/s and a maximum of 20 m/s at the moment.
