Avalanche Bulletin
更新日時: 2025/03/18 05:30
Hakuba
Alpine Fair
Treeline Fair
Below Treeline Fair
信頼度：○ good □ Fair △ Low
Travel and Terrain Advice
Even if the weather improves, this is not a day to let down our avalanche alert. Yesterday, fresh snow is sensitive to human stimulation. Today, assuming it continues to do so, careful route setting and conservative terrain selection are needed. Avoid large open slopes and start the day on smaller terrain with gentle slopes. When doing so, be sure to check for instability within the new snow and bonding of new and old snow. On steep south-facing slopes, there is potential for large avalanches to occur if solar radiation causes the new snow to develop slab tendencies. Once again, a low-pressure system is approaching, and a heavy snowfall is forecast to begin at night. Plan your activities with this in mind.
Avalanche Problem
ウインドスラブ Wind slab
Yesterday during the day, storms of over 20 m/s were blowing on the main ridge. Look for traces of wind slab formation on the snow surface and act accordingly to avoid any hazards. Be alert for steep slopes deposited by cross loading as well as just below the ridge line.
ストームスラブ Storm slab
Midwinter-like cold air is in the air and the snow is cold. As a result, it will take time to resolve the instability that was sensitive to human triggering yesterday. Furthermore, as the new snow on the surface layer intensifies the characteristics of the slab, in combination with the hard Melt-Freeze crusts in the lower layers, avalanches will be more likely to occur.
概要
Avalanche
Many storm slabs of size 1-1.5 were reported yesterday (17th). All of them were caused by ski cuts or other human triggering. Several shooting cracks over 5 m in length were also reported.
Snowpack
The stormy weather that began with the passage of a low pressure system on March 16 brought 50-60 cm of new snow at higher elevations than in the upper part of the below treeline. Yesterday (March 17), numerous avalanches and shooting cracks were observed in the fragility within this new snow. Tenperature gradients have been reported for bonding with the old snow, the Melt-Freeze crust, and continued vigilance is needed.
Weather
The Japan Meteorological Agency is forecasting winds from the south, then from the north, clear skies, cloudy in the evening, snow in places late in the evening, and a daytime high of 8 °C (418 m elevation) for northern Nagano Prefecture. At AMeDAS Hakuba (elevation 703 m), the temperature is -5.0 °C (as of 5:00 pm), with 8 cm of snow having fallen in the past 24 hours. At the main ridge (elevation 2,400 m), the temperature is -15 °C (as of 5:00), with northerly winds averaging 7 m/s and a maximum instantaneous wind speed of about 10 m/s.
