Avalanche Forecast
Regions: Mt Hood.
Back country travel is not recommended near and above tree line Wednesday at Mt Hood at least until there is more information. Dangerous avalanche conditions are also expected below treeline Wednesday at least until there is more information.
Detailed Forecast
Light snow showers mainly near and west of the crest should end on Wednesday morning. A short relative break should be seen Wednesday afternoon.
New deep wind slab from the system Tuesday and Tuesday night is likely at Mt Hood on Wednesday. This is most likely on lee north to southeast slopes near and above treeline.
New deep storm slab from the system Tuesday and Tuesday night is also likely at Mt Hood on Wednesday. This should be seen in areas that rapidly accumulated deep new snow.
Back country travel is not recommended near and above tree line Wednesday at Mt Hood at least until there is more information. Dangerous avalanche conditions are also expected below treeline Wednesday at least until there is more information.
Also here is a heads up that a strong wet warm front is headed our way for Thursday.
Snowpack Discussion
A continuous period of active weather for about the past week has brought about 3-4 feet of snow to NWAC stations at Mt Hood. 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 inch 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 inches of water on Sunday brought up to 6 inches of wet snow at Meadows and Timberline.
Limited small wind slab avalanches to 14 inches on northeast slopes above tree line via avalanche control was reported by the Mt Hood Meadows pro patrol so far Tuesday.
A fairly vigorous surface low pressure and frontal system will cross the south Cascades Tuesday and Tuesday night. This should bring strong winds and heavy snow to Mt Hood. A minor drop in snow levels should be seen following this system.
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: Very 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: Very Likely
Expected Size: 1 - 1