Avalanche Bulletin
更新日時: 2025/02/16 05:30
Hakuba
Alpine Fair
Treeline Fair
Below Treeline Good
信頼度：○ good □ Fair △ Low
Travel and Terrain Advice
The effects of the previous strong winds are still very much present on the mountain. There are some hard snow exposures and very difficult skiing shukaburras on the ridges. At lower elevations, crusts are also forming due to the high temperatures. Although the avalanche danger has decreased, consider that on very steep and extreme terrain there is still unstable snow. There is still plenty of good snow on shaded slopes unaffected by the wind. Tomorrow begins a long cycle of stormy weather. Have a good weekend.
Avalanche Problem
ウインドスラブ Wind slab
Beware of unstable slabs forming in terrain pockets.
点発生湿雪雪崩 Wet Loose snow
Depends on the degree of temperature rise during the day and the effect of solar radiation
概要
Avalanche
Yesterday (February 15), snowballs and loose snow avalanches (size 1) were observed on steep slopes below 1,800 m elevation, which are strongly affected by solar radiation and high temperatures. A size 3 avalanche occurred at 17:00 on February 14 at Kuzurezawa, Happo One. The avalanche's fracture depth is more than 3 m thick, and the running elevation is 1,000 m. Please check the video and photo on X (@npo_jan).
Snowpack
Yesterday's (15th) high temperatures and solar radiation have advanced the settling and sintering of the stormy snow; in areas affected by the storms of the 13th and 14th, numerous exposures of hard old snow surfaces and shukabras have been formed. Melt-Freeze crusts (formed on February 3) are faceting, which is reducing their strength. In addition, facets snow (1 mm grain size) has formed on its upper surface. This persistent weak layer varies considerably from place to place in terms of both the depth of burial and the state of formation. Since the weak layer is topped by snow of high hardness, the likelihood of triggering is low. However, this weak layer is also related to avalanches in Kuzurezawa, and will be investigated further. Remember that there is a hidden element of uncertainty on the steep southern slopes above 1,800 m elevation that could trigger a large avalanche.
Weather
The Japan Meteorological Agency is forecasting northerly winds, clear skies, cloudy morning and evening, snow or rain in places until morning, and daytime highs of 10 °C (418 m elevation) for northern Nagano Prefecture. At AMeDAS Hakuba (elevation 703 m), the temperature is -0.8 °C (as of 5:00 a.m.), with no new snowfall in the past 12 hours. On the main ridge (elevation 2,400 m), the temperature is -7.5 °C, with northerly winds averaging 12 m/s and a maximum instantaneous wind of 18 m/s.
