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Avalanche Forecast

Archived

Dec 24th, 2019–Dec 25th, 2019

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

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You may still be able to trigger a stubborn storm slab at upper elevations on steep, northerly slopes. Remind yourself that we’re only 4 days removed from an enormous loading event and at upper elevations, reports and information are scarce. Evaluate the terrain you’re on and your party’s exposure in the event you trigger a large avalanche.

Discussion

Santa brought Christmas presents early to the West North zone in the form of 3-4ft+ of snow (7.5in water) we received December 18-21 and now we’re on that long drawn out tail of the avalanche cycle histogram. This was the most impressive storm so far this winter and it produced a widespread avalanche cycle with numerous natural and triggered avalanches to size D3 occurring Friday and Saturday. Since the precipitation ended on Saturday, the storm snow settled 10” with a slowing rate of settlement indicative of a gradually stabilizing storm slab. 

On 12/24, Mt. Baker Pro Patrol evaluated several nicely rounding weaker layers near the base of the snowpack on a NE aspect at 5080 ft and found these layers were not reactive in tests. It’s worth keeping these early season weaknesses in the back of your mind given the recent loading event, but we don’t have evidence that they are of concern without a major loading event.

While the deep, unconsolidated snowpack continues to settle, snow immersion and tree well accidents are common. Travel with a partner and keep them in sight. Find out more information here.

Merry Christmas! We extend our gratitude in advance for submitting observations to NWAC so we can help you enjoy your holidays safely.

Snowpack Discussion

New Regional Synopsis coming soon. We update the Regional Synopsis every Thursday at 6 pm.

 

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.