Avalanche Forecast

Fair - Due to limited field observations

A low pressure system over the Gulf of Alaska is moving a strong Westerly flow through the forecast period. This will bring a mix of frontal systems, and ridges. These fast moving systems will be hard to time, and they'll bring light-moderate amounts of precipitation accompanied by periods of clearing and sunshine. A building ridge will develop Friday through the weekend. Dry conditions, warming temperatures, and intense solar radiation will persist through the weekend. Thursday: Mainly dry. Ridgetop winds light from the SW. Freezing levels 1800 m. Friday: Light-moderate precipitation early morning up to 15 mm. Ridgetop winds light from the SW-W. Freezing levels 1400 m dropping to valley bottom overnight. Saturday: Dry. Ridgetop winds light from the SW. Freezing levels 2000 m.

Recent avalanche observations include a couple of skier triggered (controlled) size 1.5 loose wet avalanches from East aspects. Spring conditions exist in the region. Exposure to the sun, warm temperatures, and periods of rain are the most likely factors to influence the avalanche danger. If the temperatures go below freezing overnight, strong crusts should develop that are likely to hold the snowpack together. If the sun shines for a few hours, the crusts may break down quickly and moist surface snow avalanches may start running naturally. Continued warming from more sun, rain, or no overnight freeze, may cause surface avalanches to step down and trigger deeper wet slab avalanches. Prolonged warming may cause very deep releases on weak layers that were deposited early in the season, or on depth hoar that developed during the winter. It is important to monitor the temperature and the freezing levels as they may change rapidly from day to day, and as you travel through different elevations.

Last week, very warm temperatures affected all but the highest north facing slopes. Spring-like conditions exist, with a melt-freeze crusts on most aspectss. Since last weekend, mostly light to locally, low density, moderate amounts of new snow have fallen forming soft slabs on the resulting crust while rain has continued to penetrate and weaken the snowpack at lower elevations. Up to 80cm below the surface, you will find another crust in the alpine and at treeline that may have been reactive (most likely on Southerly aspects) with warming throughout last week. The mid-February buried surface hoar layer is down about 200 cm, although avalanches releasing on this layer represent an extremely low probability-high consequence scenario. Cornices in the region are very large. With spring temperatures, these are more likely to become weak and fail. They could provide a large enough trigger to release deep layers on slopes below. For more information on Spring Conditions and ways to mitigate risk, please visit the new Forecasters Blog Post.