Avalanche Forecast
Regions: Mt Hood.
The main avalanche problem at Mt Hood should be small lingering wind slab on the most sheltered northwest to southeast slopes above treeline.
Detailed Forecast
A weak upper trough should begin to linger over BC and the Northwest on Monday. West winds should generally decrease in the Olympics and Cascades by Monday. The trough will cause decreasing clouds in the Olympics and north Cascades but more clouds and some light rain or snow in the south Cascades mainly at Mt Hood Monday afternoon and night with further cooling.
The main avalanche problem at Mt Hood should be small lingering wind slab on the most sheltered northwest to southeast slopes above treeline. Watch for firmer wind transported snow mainly on these aspects. The recent warm weather should have consolidated and stabilized snow on most other aspects.
Snowpack Discussion
Weather and Snowpack
An atmospheric river arrived Tuesday 1/17 with heavy rain up to about 7000 feet on Mt. Hood.
From Thursday 1/19 through Sunday, 1/22, generally 15-20 inches of snow accumulated at NWAC Mt Hood stations.
Fair weather with light winds and cool temperatures occurred Monday and Tuesday. A period of shifting and gusty winds Tuesday night helped redistribute recent snowfall to a variety of aspects by Wednesday morning. Light showers Tuesday and Wednesday produced about 1 to 4 inches of new snow.
A large upper ridge and warm air mass built over the Northwest Thursday to Saturday. By Saturday temperatures have reached the 40's with light winds at the NWAC Mt Hood stations.
A front is crossing the Northwest on Sunday afternoon causing southwest winds and cooling at Mt Hood. Little if any new rain or snow is expected at Mt Hood by Monday morning.
Recent Observations
NWAC pro-observer Laura Green was at Mt Hood Meadows Thursday and Friday and reported dripping trees and roller balls due to loose wet snow on solar slopes. She reported a general lack of weak layers with ice layers in the snow pack on most aspects but good skiing still to be found on some slopes depending on aspect, elevation and timing.
A worthwhile conditions report for the Reid Glacier for Friday is also available via the NWAC Observations page.
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.
Likelihood: Possible
Expected Size: 1 - 1