A series of significant outflow (north) wind events alongside very little precipitation over the last 2 weeks has left our forecast area with a heavily wind damaged upper snowpack.  Very hard (pencil-knife) wind slabs exist on the lee side of high elevation ridges and cross loaded gullies(SE-NW). Windward aspects have been stripped down to older layers of the snowpack and in some places the ground.  Decreasing temperatures and time have allowed for old wind slabs to gain strength.  On 3/11 these wind slabs were found to be unreactive to triggers while traveling on slope and in stability tests.  

Wind slabs may have been deposited atop near surface facets in wind sheltered terrain. These would be the areas where a moderate hazard still exists and the potential for human triggered avalanches up to 1 foot in depth remains. Although, these areas are very isolated within our forecast area due to the strength and duration of recent north wind events.  A strong temperature inversion earlier in the week has left us with melt freeze crusts on east, south and west aspects.  This in combination with very hard wind damaged snow has created slide for life conditions in steep terrain.  

Other persistent interfaces exist in the mid snowpack.  At this time, it is unlikely to affect these layers due to the minimal effect a person, or machines weight would have on the current snowpack.  Human triggered avalanches are unlikely, maintaining safe travel protocols is recommended. 

Recent outflow winds have stripped many areas, which has led to an overall decrease in the mass of our snowpack.  Some areas did see depositions add to the depth of the pack, but the strength of winds we received has done more scouring, stripping and sublimating than redistributing and depositing.  

 The overall snowpack has become thinner over the last 2 weeks in most locations.  Depth hoar is now closer to the surface and may increase the possibility to see full depth avalanches once significant loading events occur in the future, or the suns energy is able to penetrate deeper into the snowpack on south aspects.  Another affect of depth hoar being closer to the surface is that these grains that are currently rounded in many locations may be moving toward faceting again as temperature gradients increase.   Currently, affecting this layer remains unlikely.  Although, may become an issue later in the season especially if our snowpack continues to be eroded by strong wind events, and an extended period of clear and cold.

This weak snow mentioned above was created by early season cold temps, dry conditions and strong north winds.  Poor structure near the base of the snowpack has been observed since late November.  Mild temperatures and consistent snowfall during mid winter allowed this weak snow to slowly round and gain strength.  This weak snow has been dormant through the majority of the season with human triggered avalanches being unlikely at this layer.  As the sun has come out on 2/20 for the first time in weeks several very large natural avalanches  occurred with cornice and ice falls being the triggers.  Human triggers remain unlikely at this layer, although these events show that large triggers can affect this weak snow.  Cornice fall will be the most likely trigger to affect this weak snow, although it is possible that a large group could have the same affect.  Avoid overhead exposure to cornices.

In most location facets near the ground have been found to be rounding and unreactive in stability tests.  In thin areas of the snowpack basal facets have been found to be more developed with propagation present in stability tests (PST‘s).   If you find it is possible to push a ski pole to the ground in areas you travel, assume that a weak faceted snowpack exists in that location. These areas could act as a trigger point.