Avalanche Forecast
Regions: Mt Hood.
Dangerous wind slabs may be large to very large on Tuesday. While some of these may be difficult to human trigger, it may be possible to release large avalanches if triggered from a shallow area of the slab. Dangerous avalanche conditions exist, making conservative decision-making and cautious route-finding is essential.
Detailed Forecast
A weak front should pass overnight Monday, followed by light showers tapering off Tuesday morning. Another frontal system is expected late Tuesday afternoon and night. Â
New, shallow wind slab should be found mainly on lee north to east slopes near and especially above treeline. Generally avoid wind loaded slopes above treeline. Â
Wind slab should be found mainly on lee north to east slopes near and especially above treeline. Very large avalanches are possible on lee slopes if initial releases are able to step down to a crust formed earlier this month. Generally avoid wind loaded slopes above treeline. Â
Snowpack Discussion
The latest period of active weather from January 12-18th has accumulated about 3 feet of snow at both the Mt. Hood Meadows and Timberline Mt Hood NWAC stations. Fluctuating snow levels over this period has occasionally mixed rain up into the near treeline elevation band during this storm cycle.
A very active day on avalanche control was seen at Mt Hood Meadows Friday. The pro patrol reported explosively triggered widespread 1-4 foot slab avalanches on north to east slopes above treeline releasing on a crust from last weekend along with very sensitive ski cutting as well.Â
On Saturday, rain moved up to at least 6000 feet by late morning with snow levels lowering by mid-afternoon. Visibility was limited, but Meadows pro-patrol found 8-12" wet slabs very sensitive to ski cuts on steeper slopes below treeline. Steady winds continued to load lee aspects near and above treeline Saturday. Another 0.50 - 1 inch of water on Sunday brought up to 6 inches of wet snow at Meadows and Timberline through 5 PM.Â
The most recent 6-9 inches of snow received by early Monday fell at steady temperatures, but with strong winds above treeline, likely building new wind slab and hard slab conditions on lee slopes above treeline.
Avalanche Problems
Wind Slabs
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.
Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..
Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.
Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2
Storm Slabs
Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. 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.
You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1