Avalanche Forecast
Regions: Mt Hood.
Wind slab will need to watched for on on Tuesday a variety of aspects. New shallow storm slab will also be possible on Tuesday.
Detailed Forecast
A couple more weak short waves and weak bands of precipitation should move out of a large weak trough and over the Northwest on Tuesday. Several inches of snowfall is possible at Mt Hood.
Wind slab will need to watched for on a variety of aspects. Old wind slab may still be found on the more usual north to southeast slopes.  Wind slab from over the weekend is more likely on west aspects.
New shallow storm slab will also be possible on Tuesday. Warming of more than a few degrees would help make new snowfall somewhat upside down with denser snow near the surface which contributes to instability.
Snowpack Discussion
Fair weather was seen the last couple days of December through the weekend. This weather caused lots of consolidation and stabilizing of the heavy snow from December. By Thursday through Saturday, moderate to strong east-northeast winds had significantly scoured or transported available surface snow onto lee westerly aspects, mainly in the near and above treeline elevation bands.
NWAC observer Laura Green was in the Newton Creek drainage Friday and found good skiing in non-wind affected terrain. Even on wind loaded slopes near treeline, the denser wind slab was bonding to underlying snow and no natural or skier triggered avalanches were noted. Significant wind loading continued to occur on the upper mountain Friday and to lesser extent Saturday.
Surface snow sculpted by wind and active wind transport. Photo: Laura Green
By Monday morning the Mt Hood Meadows pro patrol reported warming and a widespread 1 cm freezing rain crust up to 7000 feet. This layer was not reactive to tests and should not create a new avalanche danger and will give poor ski conditions.
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: All elevations.
Likelihood: Possible
Expected Size: 1 - 1