The latest low pressure system that rolled through on 3/30 delivered varying amounts of new snow to our area.  Low lying locations received a trace- 2 inches, while upper elevations received 4-12 inches.  Higher amounts are possible to the SE of Thompson Pass outside of our forecast zone.

North winds are forecasted to be in the 20-30 mph range with gusts to 40 in wind channeled terrain and along high elevation ridge lines.  This will be redistributing the 3/30 new snow in specific locations.  Wind slabs less than one foot in depth can be expected above 3000′ in cross loaded terrain, and the lee side of high elevation ridge lines and terrain features.  These slabs could be reactive to triggers.  Below 3000′, wind slabs are less likely due to very little loose snow available for transport.  Areas near the top of Thompson Pass could still see wind slab development below 3000′ due to the strength of expected wind in that specific area.  Use test slopes and dig hand pits to determine the depth and sensitivity of wind slabs in the area you choose to travel.  Avoiding top and cross loaded terrain that is being actively loaded would be wise today.

In isolated locations fresh wind slabs may be deposited on top of surface hoar that was buried on 3/30 (see problem 2).  This would make wind slabs more sensitive with wider propagations possible in those locations. 

Surface hoar that was buried on 3/30 has been reported as existing in isolated locations.  In one location this layer was reported as being reactive in upper elevations of the Maritime climate zone, while other areas showed better stability.  The 3/30 buried surface hoar layer is expected to be spotty or isolated in its distribution.  This can create the potentially dangerous set up where a group can be lured into complacency as good stability is encountered in some areas, while slopes in close proximity could harbor a persistent weak layer.  Assessment on a slope by slope basis will be important until we can get more information on the distribution and sensitivity of this layer.  Incremental snowfall looks likely mid next week which will be adding stress to this layer.  This layer has the possibility of existing at mid-upper elevations on northerly aspects.

In addition to buried surface hoar, the sensitivity of layers within the Hamilton storm snow (3/17) and the 3/17 interface have been decreasing.  Low sensitivity to skiers and snowmachiners traveling in steep terrain as well as positive results in stability tests are all pointing to a low likelihood of triggering an avalanche at these layers.  Some large human triggered and natural avalanches have been reported although it has been over a week since these occurred, and all of these were outside of our forecast zone.  Even though the likelihood is low, consequences would be high.  It is still important to asses the depth and sensitivity of potential weak layers in the snowpack when deciding to travel in steep and/or consequential terrain.

Wet loose activity will become likely below 4000′ on SE-W aspects once the sun is able to break through the clouds. New snow is expected to quickly be affected by the sun today, although may be limited in areas seeing high winds which would keep the surface cold.

The size of the terrain being exposed will directly correlate to the size of natural activity that is possible.  Small slopes will likely only produce roller balls and low volume wet loose activity.  While large steep solar aspects have the potential of entraining significant amounts of snow and producing very dangerous, large wet loose avalanches.  Step downs to slab activity will become increasingly possible as the Spring moves on and the sun becomes more intense.  

Assesment and avoidance of this avalanche problem is relatively easy.  Pay attention to the amount of warmth that is being transferred into the snow surface (Is it becoming moist-wet?).  Avoid traveling on or being exposed to steep south aspects during the heat of the day.

Weak snow exists at the base of our snowpack.  This weak snow is currently unlikely to be affected due to the strength of old wind affected snow at the 3/17 new/old interface.  Depth hoar may become a concern later in the season if our area returns to a period of major snowfall and the very strong wind damaged layer at the new/old interface starts to break down and lose strength within the snowpack.  As very hard wind slabs break down within the snowpack a person or machines weight will have a more direct affect on weak layers at the bottom of the snowpack.  In addition,  the increasing intensity of the sun will be putting pressure on deep layers during the heat of the day.