The higher elevations have received five feet of snow with over six inches of moisture since January 1. The snowfall has been accompanied by strong and gusty winds. Last night was no exception as heavy snowfall and sustained winds continue to increase the hazard at all elevations today. Human triggered slab and loose snow avalanches are likely. Natural avalanche releases are possible. Expert terrain evaluation skills and conservative decisions are essential for safe travel in avalanche terrain today.
Strong west to southwest winds have transported snow onto leeward aspects. These slabs will be further loaded today by new snow and southwest winds. Above 8,000 feet, backcountry travelers could trigger these slabs with depths up to three feet. Below this elevation, pockets of wind slab up to two feet in depth can also be triggered on steep, wind loaded terrain features at the lower elevations.
Weak snow near the base of the snowpack continues to be a concern. This layer has been further stressed by recent snow and avalanches involving it could release once a slope is impacted by a triggered wind slab, the weight of a single person, or a group of people. This layer has been most active on northwest to northeast slopes above 8,500 feet but can be found on other aspects as well. Being caught in one of these large hard slabs is likely to have severe consequences.
( Discussion is generated from the previous day's afternoon forecast. )A broad trough will be over the state on Thursday. Orographic lift will favor higher snowfall amounts at the higher elevations. Snowfall totals in favored areas could exceed a foot by tomorrow evening. Temperatures will be in the single digits and teens at the upper elevations and in the teens and 20’s at the lower elevations. Westerly winds will gust to 30 to 40 miles per hour on the peaks.At the mid and upper elevations strong winds and new snow will be loading available snow onto leeward aspects and will be increasing the hazard as the day progresses. In steep terrain humans can trigger wind slabs one to three feet in depth on density differences within the new snow and on old snow surfaces that formed in late December. Very large persistent deep slabs up to five feet in depth can also be triggered or release naturally on a basal layer of faceted snow. Up there the general avalanche hazard will be considerable. Pockets of wind slab up to two feet in depth can also be triggered on steep, wind loaded terrain features at the lower elevations where the general avalanche hazard is expected to be moderate.
