Avalanche Forecast

Archived

Jan 27th, 2018–Jan 28th, 2018

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Regions

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Very large and destructive natural avalanches are expected across the Mt Baker region Sunday. Avoid all avalanche terrain including where avalanches may run and stop. Avalanches may become larger and travel farther than expected, overrunning common travel routes.

Detailed Forecast

Rapidly warming air temperatures and additional heavy precipitation Sunday will create very dangerous avalanche conditions in the Mt Baker area. Avoid all avalanche terrain including where avalanches may run and stop.

Avalanches will entrain significant amounts of snow growing very large and potentially destructive. Avalanches may travel significant distances and extend far into their runouts, or valley bottoms.

In addition to the very dangerous avalanche conditions, numerous very difficult to manage avalanche and weather hazards will make it extremely hard to travel safely in the backcountry Sunday. This is a day to stay home and wait it out until this active avalanche cycle ends.

Snowpack Discussion

Significant amounts of snow have fallen in the Mt Baker area over the last ten days. Storm totals exceed 11 feet at Heather Meadows! That has settled to 6 to 8 feet of snow over the last crust layer.

Winds have redistributed snow creating deep wind slabs on lee slopes near and above treeline.

Numerous natural avalanche cycles have occurred over the storm period.

Observations:

NWAC professional observer Lee Lazara was in the Mt Baker backcountry Saturday. Lee report several large natural avalanches in the backcountry area. Poor visibility limited detailed descriptions or more extensive observations. Observations found strong surface snow over soft weak storm snow from Friday. Shooting cracks and small slope test all pointed to reactive storm and wind slabs.

Problems

Wet Slabs

Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.