Avalanche Bulletin
更新日時: 2024/03/11 06:00
Myoko
Alpine Low Be aware of the effects of solar radiation during the day
Treeline Low Be aware of rising temperatures during the day and the effects of solar radiation
Below Treeline Fair Be aware of rising temperatures during the day and the effects of solar radiation
信頼度：○ good □ Fair △ Low
Travel and Terrain Advice
This is a day of high avalanche conditions in certain terrains. Strong sunshine and significant temperature increases are forecast. Surface snow that was low cohesion and very soft in the morning may become more responsive to human stimulation as slab features intensify during the day. Terrain selection should be made by considering where the terrain has features such as convex or isolated terrains that are less able to support snow accumulation, and the impact of these features with solar radiation. This morning the snow has cooled well due to radiative cooling. If you choose the right terrain, you will be able to enjoy fresh snow that is so fresh it is hard to believe that it is March. Please remember basic group management such as stopping at safe spots and skiing one person at a time. Have a great day.
Avalanche Problem
ストームスラブ Storm slab
On very steep slopes where the influence of solar radiation is strong, slabbing of the surface snow may increase the likelihood of triggering. Avoid terrains with convex or isolated geometries that do not support snow accumulation.
ウインドスラブ Wind slab
Strong northwest winds on the main ridge have subsided since yesterday around noon. Currently, the wind is also very light. Watch for the formation of hourly wind slabs.
持続型スラブ Persistent slab
The weak layer in question was deeply buried by the recent snowfall. This has greatly reduced the triggering sensitivity and increased uncertainty. The avalanche bulletin team will continue to attempt to track this persistent slab for some time to come.
概要
Avalanche
Yesterday (10th), many size 1-1.5 storm slab avalanches and several size 2 avalanches were reported at the ski area safety control. No reports of avalanches in the mountain areas have been received.
Snowpack
The upper snowpack has fresh snow (50-80 cm) since the evening of March 8. In the below treeline area, where winds were strong yesterday, the new snow is reacting to human stimulation, causing avalanches. In the nearby Hakuba Mountains area, it has been observed that the steep slopes in the upper part of the below treeline have buried the Melt-Freeze layer resulting from the clear weather on March 8, and that faceted snow has formed on this boundary surface. As of yesterday, there are whumpfing sounds and other test results to be aware of, and caution should be exercised in the Mt. Myoko area as well, where the same characteristics are present. The weak layer of persistent slab that we are tracking is deeply buried by this new snow, and the situation is highly uncertain.
Weather
The Japan Meteorological Agency is forecasting southerly winds, northerly winds during the day, clear skies, cloudy in the evening, and a daytime high of 11 °C (13 m elevation) for the Joetsu region of Niigata Prefecture. At Sasagamine, Myoko (elevation 1,310 m), the temperature is -11 °C (as of 4:45 a.m.), with no new snowfall in the past 12 hours.
