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Avalanche Forecast

Archived

Feb 28th, 2018–Mar 1st, 2018

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

Regions

Mt Hood.

You will be able to trigger avalanches in wind-loaded or steep open slopes at all elevations Thursday. New wind and storm slabs may be found in many locations. These avalanches problems will need time to heal. Stay off of open or wind-loaded slopes over 35 degrees and use travel routes and techniques to minimize your exposure to overhead avalanche terrain.

Detailed Forecast

New and reactive wind and storm slabs formed Wednesday night in many locations. You will still be able to trigger these avalanches on Thursday.

Strong winds Wednesday night will transport storm snow to create hard wind slabs on lee slopes and cross loaded mid-slope features at all elevations. Identify and avoid steep slopes where the wind deposited snow. In some locations these wind slabs may be hidden by soft unconsolidated snow. Use visual clues such as cornices, the lack of snow in the trees, and large snow drifts to indicate wind loading on nearby slopes. Give this avalanche problem a wide berth Thursday. Wind slabs will have the potential to become very large and destructive. Use travel routes and techniques to reduce your exposure to Mt Hood’s very large avalanche paths that originate higher on the mountain.   

In wind sheltered locations, you will be able to trigger soft storm slabs up to 14” deep. Stay off of all open slopes greater than 35 degrees. Storm slab layers need time to heal. Be patient as this active avalanche pattern proceeds.

Snowpack Discussion

Wednesday several inches of snow began to fall in the Mt Hood area with increasing winds. This new snow fell on a variety of snow surfaces created during the last several days including crust on sunny aspects, wind featured snow, and unconsolidated surface snow in shaded sheltered areas.

In many locations more than 3’ of snow now sits on a firm buried crust layer (2/17). This crust has been reported up to 6600’ by professionals in the region. There are currently no significant layers of concern below the 2/17 crust.

Observations

On Tuesday, Mt. Hood Meadows pro-patrol reported wind buff and soft wind-blown powder with crusts on sunny aspects. 

Problems

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.

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.