Avalanche Forecast
Regions: Mt Hood.
The greatest avalanche problem should be wind slab on lee slopes near and above treeline mainly N-SE facing slopes. Watch for signs of firmer wind transported snow.
Detailed Forecast
Light winds, cloudy or mostly cloudy weather, a few light snow showers and cool temperatures should be seen at Mt Hood on Monday.
This weather should bring a further gradually decreasing avalanche danger on Monday.
The greatest avalanche problem should be wind slab on lee slopes near and above treeline mainly N-SE facing slopes. Watch for signs of firmer wind transported snow.
Watch for storm slab in areas that had rapidly accumulating snowfall. Storm layers that may exist above the new crust will slowly settle but could remain reactive to human triggers mainly near and above treeline.
Continue to evaluate snow and terrain carefully on Monday.
Snowpack Discussion
Warm wet weather will have caused increasing wet snow conditions at Mt Hood Wednesday-Thursday.
A strong occluded front with strong winds crossed the Northwest on Friday. NWAC stations at Mt Hood had about a foot of new snow by Saturday morning. About another 6-8 inches followed at the tail by Sunday morning.
Some areas have reported a strong bond of the new snow to the new crust and some a poor bond depending on if the new snow arrived after cooling began. There have also been sensitive storm layers reported within the new snow which will take a bit of time to gradually stabilize.
NWAC pro-observer Laura Green in the Clark-Mitchell-Heather Canyon areas reported building wind slab and building cornices on Friday.
The Mt Hood Meadows pro-patrol Saturday reported mainly 4-8 inch storm slab released by ski cuts in the above tree line.
A report via the NWAC Observations page for Pea Gravel Ridge on Saturday reported building 4-6 inch wind slab on lee slopes near ridges. Storm layers and storm slab was also noted.
Today the Mt Hood Meadows patrol reported limited 4-6 inch wind slab on lee slopes in the above tree line, lower than usual below ridges, which would be small and difficult for a skier to trigger.
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: Possible
Expected Size: 1 - 1
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