The warm and stormy period is winding down with one last pulse Tuesday. Watch for wind stiffened storm slabs at upper elevations and avoid terrain traps & convex rolls in the trees, storm snow may be resting on buried surface hoar.
A persistent weak layer exists throughout the region 80 to 130 cm below the surface. In most places it looks like the overlying snow is gaining strength and human triggering is trending towards unlikely. However, areas around the Pine Pass may remain problematic.
The region has picked up 25 to 50 cm of recent warm wet storm snow with another 5 to 10 cm expected Tuesday.
In wind exposed terrain at and above treeline the new snow has been shifted into wind slabs by ongoing west & southwest wind.
At lower elevations there may be surface hoar under all of the new snow. We haven't heard much about reactivity with this surface hoar yet, but it needs to be on your radar.
We should get one last pulse of warm storm Tuesday before entering a clearing trend that extends for the foreseeable future.
MONDAY NIGHT: Freezing level peaking out at about 1500 m, strong west/southwest wind, no significant precipitation expected.
TUESDAY: Broken cloud cover, freezing level steadily lowering to valley bottom throughout the day, strong west/southwest wind, 5 to 10 cm of snow possible.
WEDNESDAY: Scattered cloud cover, freezing level at valley bottom, moderate to strong northwest wind, trace of snow possible.
THURSDAY: Scattered cloud cover, freezing level at valley bottom, light variable wind, no precipitation expected.
On Monday our field team observed some size 2 natural avalanches on a north facing alpine feature east of Crescent Spur. These likely ran over the weekend.
On Sunday we received some great observations of avalanches running naturally on a crust in the trees in "The Farm" area, more details here.
On Friday our field team found stiff and heavily wind affected snow in the Renshaw. They spotted one size 2 wind slab that had released out of a NW facing chute, more details here.
The region has picked up 20 to 50 cm of new snow in the last week with the weekend pulse coming in warm and wet. Another 5 to 10 cm is expected Tuesday.
Underneath the storm snow you are likely to find a hard melt-freeze crust that can be found up to about 1600 m. You may also find buried surface hoar under the new snow which could make for touchy storm slabs. You are most likely to encounter it in terrain features sheltered from the wind, for example in openings below treeline. As the new snow continues to settle and forms slab properties, these layers could become reactive to human traffic.
Around 60 to 130 cm of snow rests above a weak layer buried in early-December. On Jan 14th our field team found it in the Holmes area. This setup has created a persistent slab avalanche problem and a low probability/high consequence scenario. Depending on location, the buried weak layer is composed of surface hoar and/or a crust/facet combination. Reports suggest that this layer has become dormant in much of the region except for perhaps the Pine Pass area.
