Avalanche Forecast
Regions: Mt Hood.
New wind and storm slab layers should be seen on Saturday. The skiing should be improved but don't forget to make careful snowpack evaluations.
Detailed Forecast
Strong southwest winds aloft will accompany a cold front will cross the Northwest on Friday evening. West winds will follow with orographic snow showers and a good cooling trend on Saturday morning.
The cooling trend may help bond new snow to old snow surfaces where the snow starts at above freezing temperatures. With a little luck many areas along the west slopes will have about 5-10 inches of new snow by the time snow showers taper off on Saturday.
The main avalanche problem should be new wind slab on lee slopes in the near and above treeline. Watch for signs of snowpack cracking and firmer wind transported snow on lee slopes.
A secondary avalanche problem should be new storm slab in areas with less wind if there is rapid loading. The cooling trend may help limit this avalanche problem.
Â
Â
Snowpack Discussion
Weather and Snowpack
A strong occluded front with strong winds crossed the Northwest January 29-30th. NWAC stations on Mt Hood received about 1.5 feet of new snow
Cool and benign weather settled over Mt. Hood Sunday to Tuesday with ample sunshine on Tuesday. A sun crust likely formed on solar slopes.
A cold front and then a warm front crossed the Northwest on Wednesday and Thursday. NWACÂ stations at Mt Hood for the 2 days ending Friday morning had 18-20 inches of snowfall.
Recent Observations
The Meadows pro-patrol Thursday reported heavy snowfall and remotely and easily triggered widespread 1 foot wind slab mainly on north to southeast slopes along with storm slab in the near and above treeline. A combination of storm slab, loose wet avalanches and rollerballs was seen below treeline.
A couple reports for Mt Hood are available via the NWAC Observations page from Mt Hood on Thursday with easy pit tests for storm layers or on the crust buried January 29th. Roller balls due to warm temperatures were reported below the snow level.
The Meadows pro-patrol reported less activity today with isolated wind or storm slab released by explosives or ski cuts in the near and above tree line.
Â
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.
Elevations: Alpine, Treeline.
Likelihood: Likely
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