Avalanche Forecast
Regions: Mt Hood.
Another round of storm slab and wind slab are likely Wednesday, with new wind slab mainly forming on lee slopes ranging from N-SE facing, especially by afternoon as wind speeds increase.
Detailed Forecast
Another Pacific frontal system, in the long series of recent storms, is moving into the Mt Hood area Tuesday evening. This next system will cause renewed light to moderate snow and light to moderate westerly winds Tuesday night. This should begin to build new areas of wind slab on lee slopes below ridges and create some isolated storm slabs. Moderate to heavy showers should persist with increasing westerly ridgetop winds through the day Wednesday.Â
Dangerous avalanche conditions should persist Wednesday in all elevations bands and especially in the near and above treeline zones.Â
Expected avalanches should remain within the near surface storm related weak layers. Watch for evidence of wind deposited snow or pillows. Test for inverted of strong over weak storm snow and give cornices a wide margin.
The recent unconsolidated storm snow is now very deep, two to over three feet in places! There was a snow immersion fatality in a tree well in bounds at Snoqualmie on Saturday, and a close call at Crystal Mtn Tuesday, so always travel with a partner.Â
Snowpack Discussion
About 4 feet of new snow has fallen in the Mt Hood area over the past five days! Including 10-15 inches of new snow deposited from a strong storm Monday! ?The most recent reports Tuesday from patrol at Mt Hood Meadows indicate avalanches are mainly confined to recent storm and wind slab layers mostly 6-12".
A stiffer wind slab layer was found sandwiched between two weaker snow layers at about 6600 feet Tuesday.  Â
The crust formed December 17th is now buried deeply and may have broken down or just not be involved in recent avalanches and is becoming less a player with each day's new storm snow accumulations.Â
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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, North West.
Elevations: Alpine, Treeline.
Likelihood: 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: Likely
Expected Size: 1 - 1