Avalanche Forecast
Regions: Mt Hood.
Recent wind slabs should be primarily on N-E aspects but be alert on all terrain aspects firmer wind transported snow.
Detailed Forecast
An upper ridge should drift across the Northwest on Friday. In the Olympics and Cascades this should cause some high clouds, light winds and gradually moderating temperatures west of the crest and at higher elevations.
Recent wind slabs at Mt Hood should be primarily on N-E aspects but be alert on all terrain aspects for firmer wind transported snow.. The benign weather should bring a little more stabilizing to these layers on Friday. Remember that firmer wind transported snow is always your best sign of wind slab layers.
Small loose dry avalanches might be possible in steep wind sheltered terrain but will not be listed as an avalanche problem.
Snowpack Discussion
Weather and Snowpack
A pair of warm fronts moved across the Northwest Saturday and Sunday causing see-sawing temperatures near or above freezing at Mt Hood. The Mt. Hood Meadows base station saw a jump of over 20 degrees Saturday evening as low level easterly flow finally abated allowing milder Pacific air to move in. 8 inches of snow fell through Monday morning with another 5 inches accumulating in the Mt. Hood area at NWAC stations through Monday afternoon.Â
Mt. Hood was stacking up the new snow Tuesday with another 15-20 inches falling Monday night through Wednesday midday. Winds were generally light to moderate in this storm, but E winds increased mid-mountain Tuesday afternoon, then switched to SW Wednesday. Â
Recent Observations
All recent reports for Mt Hood are from the Mt Hood Meadows pro-patrol.
On Tuesday, the pro-patrol reported generally good skiing and riding conditions with the new snow. 6-12" storm or wind slabs were soft but could be triggered above treeline in specific areas. The patrol reported cracks propagating through the new snow, but in many areas the lack of a cohesive slab prevented avalanches from releasing.Â
On Wednesday, the pro-patrol did not venture above about 6600 feet, due to white out conditions. Below this elevation, in the mostly below tree line band, sheltered slopes were maintaining right side up powder conditions that lacked any slab structure, providing excellent conditions.
On Thursday, the pro-patrol reported one natural 8 inch x 300 foot wide natural slab avalanche occurred Wednesday on a S slope at 6500 feet. Otherwise on Thursday only pockets of 4-10 inch wind slab were released by explosives on N-NE slopes in the near and above treeline due to SW winds on Wednesday.
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