Today is another day where human triggered avalanches are likely and natural avalanches are possible.  

Another round of snowfall is impacting our area over the next 24-36 hours.  This storm is coming in colder than the last set with snow currently falling to sea level.  This may change today with snow line forecasted to rise to 1000 feet by this evening.  Our area has received  4-10 inches so far depending on proximity to the coast (Coastal locations recieving more snow).  6-12 additional inches of snowfall is expected before the current storm departs.  

Storm slabs are forming on a variety of surfaces ranging from a little bit of snow on stout rain crusts at low elevations to older storm/wind slabs from last weekend at upper elevations.  New snow may become upside down at low elevations if the forecast proves true and snow levels rise to 1000 feet.  Above the freezing line new snow will be added stress to wind slabs that were previously sensitive.  We may also receive enough new snow that new storm slabs form widespread instability on slopes steeper than 30°.  

Added to that winds are forecasted to be moderate to strong today and have switched directions from SE to NE at the surface.  At upper elevation winds are expected to remain SE.  This may sound confusing, but the takeaway should be that you should expect to find fresh wind slabs on a variety of aspects.  New snow avalanches may be able to step down to deeper layers in the snowpack and create very large destructive avalanches (see problem 3).

There is a lot of uncertainty out there at the moment as to the variable depths of storm slabs from the last week and how well they are bonding.  What we are certain of is that precipitation has been occurring over the past 9 days atop a snowpack with poor structure on Thompson Pass and areas north.  If you choose to recreate in avalanche terrain today it will be important to pay attention to red flags that the snow gives us.  These include: Shooting cracks, collapsing, active wind loading, and natural avalanche activity.

The forecast currently indicates for the snow line to rise to 1000 feet as the day goes on.  This would create the possibility to trigger wet loose avalanches in steep terrain at low elevations.  Be aware that wet loose slides often have more force than expected and can be hazardous if they are able to carry you into dangerous terrain, ex: cliffs or terrain traps.  Pay attention to the density of the snow surface and use caution in steep terrain if rain begins to fall on dry snow.

This avalanche problem will not exist today if the forecast does not prove true and snowfall continues down to sea level.

In many locations developed facets exist in our mid to lower snowpack.  These facets have been stressed by warm temperatures and heavy precipitation.  These weak layers will need time to adjust to the added weight that the recent storms have delivered.  In many areas above 3000′ these facets have been capped by knife hard wind slabs making them more difficult to affect.  Pole probing often along your route is a good way you can determine what’s overlying faceted snow in our lower snowpack.  

Storm slabs may be able to step down to these weak layers creating very large destructive avalanches.  The most likely place to encounter this avalanche problem is in the Continental zone in thin rocky areas where weak faceted layers are more easily affected.  

(2mm grid) Photo of chained facets found in the low elevation area of Girls Mountain 1/13.  In many areas these facets are capped by knife hard wind slabs making them difficult to affect and detect.