Avalanche Forecast
Regions: Mt Hood.
Avoid steeper terrain features with previous or newly forming firmer wind transported snow. Be prepared to step back from your plans if the next system arrives stronger and sooner than expected.
Detailed Forecast
The next system should bring increasing light snow to Mt Hood on Sunday, with light to moderate alpine winds, and no great change in snow levels or cool temperatures.
Keep an eye out for previous or newly forming wind slabs on Sunday. If you see signs of winds transporting snow including plumes, drifts, and uneven snow surfaces, then avoid slopes where the wind loading is occurring.
Watch for small new storm slab by the end of the day if there is more than a few inches of snowfall.
Be prepared to step back from your plans if the next system arrives stronger and sooner than expected.
Also despite all this new snow, early season hazards still exist at lower elevations and especially around creek beds that are not filled in.
Snowpack Discussion
About 15-18 inches of light snow fell at Mt Hood in the 24 hours ending Saturday morning. Around a foot of recent snow now sits atop Monday’s freezing rain layer.
Moderate to strong WSW-WNW winds were seen Tuesday to Thursday. Due to significant wind transport especially near and above treeline, height of snow can vary dramatically across terrain.
No recent activity avalanche has been reported in the area.
Observations
The Meadows pro patrol on Saturday reported now density snow to 6600 feet, no discernible failure planes in new snow, and new snow well bonded to old surfaces.
Backcountry observations from Thursday confirm the wind redistribution of snow, with bare ridges and wind slabs on lee slopes observed.
The Meadows pro patrol reported wind slabs near and above treeline formed earlier in the week. Control efforts on wind slabs within the ski area produced limited results.
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