Avalanche Forecast
Regions: Mt Hood.
Avoid freshly loaded lee slopes in the Mt. Hood area near and above treeline as human triggered avalanches are likely. Wind slab will mostly likely be found on easterly aspects. Evaluate recent snow carefully before committing to steeper terrain in all elevation bands.
Detailed Forecast
Wednesday should be cool with scattered showers increasing in coverage and intensity in the afternoon. A few sunbreaks are possible in the afternoon but generally cloudy conditions are expected in the Mt. Hood area. Â
Moderate amounts of new snow received over the last day or so should have been transported to lee easterly slopes mainly near and above treeline. Avoid freshly loaded lee slopes in the Mt. Hood area near and above treeline as human triggered avalanches are likely.Â
Generally shallow storm slabs should continue to settle and be less sensitive on Wednesday. Evaluate recent snow carefully before committing to steeper terrain in all elevation bands.Â
Loose wet avalanches will not be indicated as an avalanche problem but watch for loose wet surface snow if you find yourself on solar slopes during sunbreaks.
Snowpack Discussion
Weather and Snowpack
Hopefully the last atmospheric river of the season arrived on Valentine's Day 2/14, causing heavy rain, avalanches, crusts and significant snowpack consolidation through Thursday 2/16 at Mt. Hood. About 5-8 inches of snow fell at Mt Hood during the tail end of the storm. A short period of fair weather on Friday 2/17 caused another surface crust at Mt Hood.
A low pressure system that tracked from the Oregon Coast across the south Washington Cascades brought 10-12 inches of snow to Mt. Hood stations Sunday night and Monday along with a warming trend that peaked late Monday morning. Mid-mountain winds that were easterly in the morning switched to westerly Monday afternoon and were strong W-SW above treeline for much of Monday. Â
Light to moderate snowfall Tuesday was transitioning to light to occasionally moderate showers in the afternoon with moderate westerly transport winds. 5-8 inches of snow had accumulated during the day on top of another 7 inches received Monday night at Mt. Hood stations. Â
Recent Observations
NWAC pro-observer Laura Green was out on Sunday at Bennett Pass up to about 6000 feet and found recent snow well bonded to the 2/17 crust and observed no signs of avalanches. The Mt Hood Meadows pro-patrol on Sunday found N-E slopes up to about 6600 feet a bit loaded with 8-10 inches of wind transported snow on the 2/17 crust but no significant wind slab.
On Tuesday, Mt. Hood Meadows triggered isolated pockets of large wind slab with explosives above treeline on lee easterly aspects. One wind slab avalanche had a crown up to 5 feet! Near treeline, 6-12†storm slab was sensitive and showed good propagation with explosives and ski cuts. Below treeline, small loose dry was the only avalanche concern on steep slopes. 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, South.
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