Avalanche Forecast

Poor - Timing, track, or intensity of incoming weather is uncertain for the entire period

There is a high degree of uncertainty with regard to the weather forecast right now. Two cold fronts will affect the region this weekend bringing lowering freezing levels and an uncertain amount of precipitation. The following is my best shot at a forecast for the region. You will notice that the ranges are wide to accommodate the uncertainty. Light precipitation begins to fall Friday evening continuing through Saturday morning. 10 - 25cm are expected. Freezing levels top out around 2200 meters Friday afternoon. Saturday: Snow continues through the day Saturday, 10 -15cm are expected during the day. Freezing level holds steady near 1500m Saturday with winds out of the SW strong at ridgetop, light to moderate near treeline. Sunday: Continued snowfall Sunday through early Monday morning, 10 - 15cm expected during this period. Freezing level starts near 1500m falling to 500m by Monday AM. Winds similar to Saturday; SW strong at ridgetop, light to moderate near treeline . Very little precip is forecasted Monday & freezing levels remain near the valley bottom. Winds stay out of the SW, light to moderate at treeline, moderate to strong at ridge top.

Explosive control work produced spectacular results with avalanches to size 4 on all aspects. Crowns varied in depth from 100 - 200cm. Numerous natural avalanches were reported from size 1 - 3. I found the following report particularly noteworthy: A chunk of cornice fell from ridge top initially triggering a size 2 avalanche. The avalanche ran 50m as a size 2 before stepping down & triggering a size 3 avalanche in lower angle terrain. The crown was reported to be 200 cm in depth, failing on the Feb. 08 surface hoar.

80 cm of storm snow fell last weekend. Strong winds from the SW and fluctuating temperatures created both storm slabs and wind slabs. A cohesive slab 80-170cm thick now rests on variable old surfaces (surface hoar, facets, and crusts) that formed mid-February. These persistent weak layers have remained touchy all week and are a concern at all elevations. Easy-Hard test results, with sudden planar shears have been reported on the weak layer. If triggered, avalanches will be larger than expected. There may even be step-down potential on deeply buried weak layers. Large cornices have formed on many ridge lines.