An atmospheric river is forecasted to affect our area with 1-3 feet of snow expected over the next 48 hours at upper elevations.  A sharp increase in temperatures will accompany this storm that may drive the freezing line up to 2000′ by midday.  

Heavy new snow and rain will be falling on 4-12 inches of dry snow that is sitting on a low friction (slick) bed surface. This will create top heavy storm slabs that will be initially sensitive to human and machine triggers 1-2 feet in depth on all aspects and elevations.   If the next 24-48 hours of weather occurs as predicted, we will have all three ingredients necessary to produce avalanches.  Bed surface, weak layer and slab.

Conservative terrain choices and cautious route finding will be necessary for safe travel in avalanche terrain tomorrow.  Watch for signs of instability such as shooting cracks, collapsing and avalanche activity that would indicate unstable snow.

If we get a much stronger storm than forecasted, the avalanche hazard may rise to HIGH in some locations.

The potential for wet loose avalanches will be on the increase as freezing levels rise and we receive rain on dry snow below 1500′.  Even small wet loose avalanches in steep terrain have the potential to entrain significant mass to knock a person off their feet and carry them into potentially dangerous terrain/ exposure.  This should be a consideration for ice climbers tomorrow.

Early season rain events followed by mostly cold, dry and windy weather November through December have promoted facet growth in the bottom half of our snowpack.  This weak snow has remained dormant over the last 10 days as no major loading events have occurred. 

Heavy precipitation and rising temperatures will return to the Valdez/ Thompson Pass region and have the potential to reactivate weak layers in our lower snowpack.  It is very difficult to predict how much snow/weight it will take to make these persistent weak layers reactive.  

The predicted storm totals of the current storm is unlikely to cause a widespread natural avalanche cycle at these deep layers above brushline.  This is due to very strong snow that is capping these weaknesses caused by previous strong wind events that have been frequent through the early season. Although, the potential cannot be ruled out.

Below brushline failures at persistent weak layers will be possible in isolated locations.  These include steep slopes below 2500′ with a lack of anchors (alders) EX: steep terrain into gullies or canyons.  A lack of very hard wind damaged snow above the October facets will make these areas easier to affect.

Faceted snow near the ground from Crudbusters (continental zone) below brush line.