Avalanche Forecast
Regions: Mt Hood.
Storm slab will be possible on steeper slopes that rapidly accumulate more than a few inches of new snow. Wind slab may be encountered on Sunday near ridges and may be triggered particularly on steeper terrain.
Detailed Forecast
Light to moderate showers Saturday and Saturday night should give way to light showers on Sunday. Increasing moderate WNW winds are expected on Sunday and should be capable of transporting snow, especially near ridges and exposed terrain. See the NWAC mountain weather forecast tab for more details.Â
Five to ten inches of new snow Saturday to Sunday morning should be sufficient for the development of new areas of storm slab. Increasing winds should transport this new and older snow and create pockets of wind slab, particularly near ridges and on NW through S aspects.
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 in general new snow received post-Thanksgiving has reportedly bonded well throughout the range.Â
During the week, a series of frontal systems have generally produced light amounts of new snow for the Mt. Hood area, with 14-16" over the past six days. Temperatures during this time period have been mostly in the 20's at Mt. Hood with SW to W winds in the 10's and 20's at Mt. Hood Meadows.
Observations
On Wednesday, a professional ski patroller from Mt Hood Meadows toured to about 6600 feet, finding about 8-12" of recent storm snow well bonded to the crust from last week. Storm snow was deepest on N-E facing terrain and no avalanches were noted. Some rollerballing was noted on steep solar terrain due to direct sun warming.  Â
On Friday, NWAC observer Laura Green reported no new avalanche or snowpack concerns near and below treeline, with possible isolated pockets of wind slab above treeline. Laura noted that despite moderate winds above treeline, there was not much available snow for transport.Â
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.
Avalanche Problems
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: Possible
Expected Size: 1 - 1
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