Northwest Mountains

A week of dry weather has allowed the old persistent slab avalanche problem to gain strength and become more difficult to trigger. Recent observations have reported a quiet snowpack while still finding some good snow to ride. It is recommended that you remain vigilant and evaluate potential features of concern, such as any lingering hard slabs at upper elevations or the few slopes that didn't avalanche during last week's avalanche cycle. Yesterday, a skier triggered an old hard slab, after landing a heavy jump turn on a steep slope of 12,400ft. 

Now a week since the major atmospheric river event ended, we continue to see gradual improvements to the snowpack.  The main processes driving these changes are weak layers rounding and bonding under the slabs, such as the variety of stability tests in this observation point to. Slabs are also starting to decay as the upper snowpack facets.   In the Northwest Mountains, we've lowered the likelihood to "Unlikely."  The average slope either avalanched during the storm or is reaching equilibrium under its current load, but we anticipate isolated outliers.  We recommend more cautious travel at higher elevations because that's where lingering instabilities will be largest and because wind-affected slopes are more variable, so we have greater uncertainty.  For example, you might find a windward slope that was eroded into a very shallow and unusually weak snowpack during November and subsequently formed a wind-stiffened slab of variable thickness during the big storm: good ingredients for a slower-to-heal setup.   These avalanches in Wolverine Basin are examples of that situation.  

The same improvements are occurring in the shallower Southeast Mountains, though the decrease in likelihood is expected to be slightly slower near and above treeline. We suspect a few more slopes fit the description of unusually shallow and weak before the storm, now drifted over by a stiffer slab.  Our data from the eastern side of our forecast area is still limited this time of year. However, outside of our forecast area, regions with a shallower snowpack have shown evidence of slower-to-improve stability and a less extensive flush from the big storm.   

As the upper snowpack continues to facet and lose strength, stay alert for small loose dry avalanches on sustained, steep terrain.  The snow on top of old bed surfaces is losing strength rather quickly, as shown in this video from Mt. Axtell earlier this week. 

Events: Avalanche Awareness Night is at the Center for the Arts this Saturday. Doors open at 6, show starts at 7. We will have presentations for the first half and live music for the second half of the night. The Beacon Brush Up is then behind the Crested Butte Community School on Sunday from 9 a.m.- 2 p.m.  Details are here.