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RegisterMar 13th, 2019–Mar 14th, 2019
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Even though the avalanche danger is dropping, things aren’t that simple in the West-South zone. You’ll need to make observations to verify what avalanche problems you are dealing with and adapt where and how you travel. Pay attention to the weather Thursday, warm temperatures and filtered sunshine may combine to create loose wet avalanches. Avoid any slope where you see new rollerballs or fan-shaped avalanche debris.
Snow and Avalanche Discussion
The West-South zone is demonstrating its variability. This makes it difficult to summarize conditions and point to specific avalanche problems. Situations like this rely on observations to verify the avalanche forecast. When your observations line-up with the information you find here, then the forecast may be valid. If you see things that don’t line-up, stop, reevaluate, and dial back your terrain travel.
Adding to this complexity is a difficult weather forecast for Thursday. Freezing levels are expected to reach the highest elevations we’ve seen since January, but this may be offset by overcast skies. Make frequent weather observations and be ready to adapt to changing conditions.
The most notable avalanche Wednesday was a natural wind slab on a west aspect of Crown Pt in the Crystal backcountry. A few small loose wet avalanches and rollerballs were reported from steep sunny slopes late in the day.
A natural wind slab avalanche on the west face of Crown Pt in the Crystal backcountry. Photo: Ian Nicholson
March 10, 2019
February started stormy and cold with very active avalanche conditions on persistent weak layers. The month finished with continued cold temperatures but drier weather allowed avalanche activity to taper off. Persistent weak layers that were buried early in the month (Feb 8th) are now unreactive, though you can still find the grains.
Aside from the series of storms in early to mid-February, most regions have measured relatively light snow accumulation in the past 3 weeks. Snow has stayed soft especially on shaded slopes and faceting and surface hoar have been plentiful. While there has been plenty of sunshine since mid-February, very cold temperatures have kept melt-freeze crust to a minimum on sunny slopes.
A natural loose wet avalanche (D1.5) on a southeast aspect of Lichtenberg Mtn at 5,400ft. 3/10/2019. Photo: Josh Hirshberg
Recent Avalanches
Our attention shifted to the upper snowpack. Recent avalanche problems have largely focussed on wind transported snow and weak snow surfaces on both dry, shaded slopes and sun-exposed aspects. In some locations, a weak layer of surface hoar and facets was buried on March 6th. We’ll keep an eye on this interface as we move into the future.
A skier-triggered storm slab avalanche (D1.5) on Shuksan Arm, north aspect, 5200ft. 03/09/19 Adam U Photo.
Moving Forward
As we move further into March, there are two points to consider:
The strength of the March sun: As the sun creeps higher into the sky and the days grow longer, the sun can have a greater impact on the snow surface. When the sun comes out, expect things to change quickly. You may see avalanches conditions change with natural loose avalanches originating from sunny slopes, surface snow becoming thick and heavy, and slabs taking on a moist to wet snow character.
Weak surfaces: facets and surface hoar have blanketed snow surfaces in many zones. Any significant snowfall will bury well-developed and widespread persistent weak layers. Recently, most storms have not delivered enough precipitation to cause a problem.