Northwest Coastal

Fair - Timing of incoming weather is uncertain

Sunday: Northwest flow aloft will bring continued snowfall accumulations. Snow amounts 10-20 cm accompanied by strong ridgetop winds from the NW. Alpine temperatures near -8.0 and freezing levels near valley bottom. Monday: A low pressure system over Gulf of Alaska will move onto the north coast bringing heavy precipitation. Snow amounts 20-40 cm with strong NW ridgetop winds. Alpine temperatures near -2 and freezing levels hovering around 700 m. Tuesday: Moderate to heavy snowfall amounts expected. Alpine temperatures will fluctuate from -8.0 to an average -3.0 and could rise to above zero degrees in areas closest to the coast. Ridgetop winds will shift out of the SW in the light-moderate ranges.

Numerous size 2.0 natural slab avalanches were seen at treeline elevations from steeper terrain features. Treeline and below treeline storm slabs have shown a weak bond to the crust buried below. Active avalanche control work done on Friday concluded 1.5-2.0 slab avalanches at all elevations. A size 3 avalanche failed naturally in very steep terrain on Thursday.The avalanche danger will rise with continued storm snow accumulations and strong NW winds.

Recently, the region has seen 30-70 cm of new snow which continues to build over a variety of surfaces. These include old hard and soft wind slabs, scoured slopes, blue ice, thin melt-freeze crusts and surface hoar. Moderate to strong winds are shifting snow into slabs in the lee of terrain breaks such as ridges and ribs. Two persistent weaknesses (comprising surface hoar and facets) buried in the upper snowpack recently gave moderate to hard, sudden results in snowpack tests. The mid and lower snowpack is generally well settled and strong, although basal facets remain a concern in the north of the region.