Avalanche Bulletin
更新日時: 2025/01/04 07:00
Niseko Yotei Yoichi Shiribeshi
Alpine Good Increasing new snow fall and moderate to strong NW ridge top winds on an already loaded snow pack increase the Avalanche danger today
Treeline Good With over 15cm new snow fall amounts in the last 12 hours and forecasted throughout the day, Storm slab and wind slab avalanches are expected today in the alpine
Below Treeline Good New snow falling on yesterdays now buried sun effected snow likely created good sliding surfaces and weak layers under last night and todays new snow.
信頼度：○ good □ Fair △ Low
Travel and Terrain Advice
With increasing new snow and wind a stepping back mind set and plan for the day is prudent. Poor visibility makes it more difficult to see the exposure to slopes above and terrain traps below. Communication between your touring partners becomes more difficult. Careful planning and good communication are prudent today.
Avalanche Problem
ウインドスラブ Wind slab
As the NW winds continue and build and transport snow throughout the day, the likelihood of skier triggered and naturally released slab avalanches increase.
ストームスラブ Storm slab
Natural and human triggered avalanches very likely today below tree line. This problem will be greater in areas that have recieved more snow overnight. Yoichi area has received less new snow and the danger level should be less.
概要
Avalanche
Ski cuts produced numerous storm slab avalanches yesterday. On Shiribetsu a Size 2 avalanche large enough to injure or burry some one was triggered by a skier. Some of these avalanches were on lower angle slopes of only 30 degree. All were mid to lower elevation effected by the sun's rapid warming of the surface snow. the failure plane was reported to be in the new snow down about 20cm below the surface.
Snowpack
15cm of new snow in the last 12 is reported in Kutchan as or 4 am this morning. Moderate NW ridge top winds continued to build overnight with gusts to 15 meters per second top Annupuri. This wind is strong enough to move snow further loading lee slopes in the alpine. This new snow has buried a variety of snow surfaces. Melt freeze crusts from yesterdays solar are now expected on solar aspects tree line and below under this crust layer. this could well be the failure layer or bed surface of future slab or loose avalanches. the crust may be hard to detect and has faceted overnight and weakened further. Lower down in the snow pack, the snow continues to settle and gain strengths. As the snow pack continues to get heavier and deeper it will glide on the ground opening glide cracks and where steep enough and unsupported could open treeless slopes could release as a glide avalanche.
Weather
Today: WNW flow continues bringing moderate snow today with increasing winds. Temperatures will remain cold well and below freezing. Less new snow overnight fell and is forecasted today for the Yoichi area. Winds will increase through out the day and tonight through out the forecasted area. Less clouds, snow, and wind forecasted for the Shiribetsu area
