Avalanche Bulletin
更新日時: 2025/02/08 07:00
Niseko Yotei Yoichi Shiribeshi
Alpine Fair Limited alpine observations through the storm cycle
Treeline Good Rising temperatures today will increase reactivity of the storm snow
Below Treeline Good Rising temperatures today will increase reactivity of the storm snow
信頼度：○ good □ Fair △ Low
Travel and Terrain Advice
Monitor rising temperatures today and look for signs that the surface snow is becoming cohesive and forming into a slab. Its also important to remain vigilant about the persistent slab as there will be fewer indications that this is a problem. It will be stubborn to trigger but could release as a large size avalanche. Nicer weather today will allow skiers to travel higher in the mountains however conservative terrain choices are still recommended given the complex snowpack structure and uncertainty with the distribution of the persistent problem.
Avalanche Problem
ストームスラブ Storm slab
Rising temperatures today will cause the storm snow to settle into a slab and become reactive.
ウインドスラブ Wind slab
West and Northwest winds have caused windslab to develop on leeward slopes
持続型スラブ Persistent slab
The persistent problem is found primarily on sheltered slopes in the Northern part of the region (Kiroro/Kokusai area). Rising temps today may cause it to wake up and become more reactive.
概要
Avalanche
Cornice collapses have been reported across the region along with numerous loose dry avalanches on steep slopes.
Snowpack
A cold clear night last night likely caused surface hoar to form on the snow surface in sheltered areas, exposed to the sky. HST varies from 50-100cms across most of the zone overlying the Jan. 28 PWL. The PWL continues to be a concern and tests in the Kokusai backcountry yesterday produced sudden planar results down 50cms. The storm snow has also been re-distributed by West and NW winds forming windslab and cornices over leeward slopes.
Weather
After a break in the storm cycle, a deep low is forming to the East of Hokkaido that will begin to draw a northerly flow across the island. Light northerly winds will increase to moderate later in the day. Skies will be mostly clear in the morning before before clouds roll in bringing the occasional snow shower. Precipitation will increase in the late afternoon and overnight. Temperatures were very cold over night (-18C was the overnight low in Kutchan) but will rise to near 0C in the valley by mid-day.
