Northwest Mountains

The likelihood of triggering a slab avalanche slowly decreases; however, if you do it could be very large (like these recent avalanches on Mount Baldy 1, 2).  You are most likely to release a slab where the snowpack thins to a below-average depth.  You can reduce your risk of avalanches by avoiding shallow areas like wind-eroded slopes, rocky terrain, or features with highly variable depths.  Favor terrain with a deep uniform snowpack.  By the afternoon, the March sun will wet snow surfaces and create a loose avalanche problem on steep southerlies.  There is a small chance that loose avalanches pry out a slab as they run.  Monitor surface wetness and move to a cooler snowpack if you find more than a couple inches of wet surface snow.

A spring-like day creates both dry and wet avalanche concerns.  Temperatures are forecasted to rise several degrees warmer than Saturday and this expectation is reinforced by last night's lows running around 5 degrees warmer than the previous night.  Warming conditions are likely to cause a Wet Loose avalanche concern.  Avalanche size remains relatively small, but higher elevation east and west aspects may produce bigger loose avalanches as recently dry surface snow becomes wet.  Additionally, a chance exists for loose avalanches to release a deeper slab.  This less-likely scenario could occur on shoulder aspects where the Wet Loose problem overlaps with the Persistent Slab problem.  Keep tabs on the wetting surface snow throughout the day and remain cautious of triggering a Wet Loose avalanche on slopes with a Persistent Slab problem.

The Persistent Slab problem is the more dangerous issue on Sunday.  There is a notable difference in the likelihood of triggering a Persistent Slab between the Northwest and Southeast Mountains.  In the Northwest Mountains, the snowpack is commonly 2 meters or deeper.  It is harder to trigger an avalanche with a deep and uniform depth snowpack, but there are places where the snowpack thins and triggered avalanches become more concerning.  Wind-eroded, rocky terrain, or slopes that previously avalanched this winter will have shallower than normal snowpacks.  The perfect case and point is the avalanche activity from the west side of Mount Baldy on Friday.  Two dangerous avalanches failed in a generally shallow and variable snowpack (1,2). Take a moment to watch the video in this observation and consider the magnitude and dire consequence of releasing a Persistent Slab.  Steer clear of slopes where you expect to encounter a shallower snowpack and trigger points.  Warming temperatures may slightly increase the risk of natural cornice fall which could act as a trigger for a dangerous slab avalanche.

In the Southeast Mountains, the snowpack is generally shallower with depths commonly less than 2 meters.  A shallower snowpack increases the chance of you impacting weak layers and releasing a deadly avalanche.  Recent avalanche activity points to this increased risk with dangerous remotely triggered avalanches on Double Top, West Brush Creek, and an accident just outside the Southeast Mountains zone near Italian Mountain.  Take a look at this video from Double Top to get a better visual on the increased risk of riding steep terrain in areas with a shallower snowpack.  Take a cautious approach to your terrain selection in the Southeast Mountains particularly in areas with less than 2 meters total depth (this is much of the Southeast Mountains).  Don't expect warning signs before releasing a dangerous avalanche.