Avalanche Forecast
Regions: Mt Hood.
Watch for mostly small wind-loaded pockets on steeper terrain, particularly above treeline. Approach ridges cautiously and watch for firmer wind-transported snow. Storm slab is less likely, but continue to evaluate the upper snowpack as you travel.
Detailed Forecast
Decreasing clouds and decreasing NW winds should be seen on Monday at Mt. Hood.
Wind slab is replacing storm slab as our primary avalanche problem as storm snow will be more rapidly stabilizing. Small to large wind slabs should remain most likely on NW through S aspects on Monday and should become less sensitive to trigger. Watch for areas of firmer, wind-transported snow mainly on lee terrain features.Â
Storm slab layers in the upper snowpack are still giving test results at multiple locations along the west slopes of the Cascades on Sunday. Similar snow layers may be present, but less likely at Mt. Hood due to lower precipitation intensities. These layers should continue to heal where present on Monday.
Early season terrain hazards still exist, such as poorly covered rocks, vegetation and creeks, particularly at lower elevations.
Snowpack Discussion
Warm, wet weather before Thanksgiving caused wet snow and glide avalanches as well as significant snowpack consolidation. There are no snowpack concerns below the Thanksgiving crust and new snow received post-Thanksgiving has reportedly bonded well.
A series of frontal systems produced snow over the past week since the Thanksgiving warm period: NWAC stations at Mt. Hood received 20-23" of snow.
This includes the recent snow accumulation for the 48 hours ending on December 3 at NWAC stations of 7-8".
Since last Monday, temperatures at NWAC Mt. Hood stations have generally been steady in the upper 10's and  20's at higher elevations and winds have been mostly SW to W in the teens and 20s. However, at the top of Mt. Hood Meadows (Express Station), winds on Sunday have been in the 20's with gusts mostly in the 50's to 70's.
Observations
On Saturday, the Mt. Hood Meadows Ski Patrol reported 13†of increasing density snow over an impenetrable Thanksgiving crust. Tests gave no results on an east-facing slope at 6600 ft.
On Sunday, the Mt. Hood Meadows ski patrol found sensitive low-density 8-10" small, ski-triggered wind slab on specific, isolated ridge-top features near 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: All aspects.
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: Alpine, Treeline.
Likelihood: Unlikely
Expected Size: 1 - 1