Avalanche Forecast
Regions: Mt Hood.
A storm with strong shifting winds, heavy snow and rapid loading is expected at Mt Hood on Monday. Back country travel is not recommended above and near treeline at Mt Hood on Monday.
Detailed Forecast
A strong low pressure system will move west to east across Washington on Monday. There should be a big difference in the weather and avalanche conditions between the north and south Cascades with the strongest winds and heaviest snowfall in the south Cascades. But a different track of the low could bring much different than expected weather and avalanche conditions on Monday so the forecast is somewhat uncertain.
This storm should bring strong shifting winds, heavy snow and rapid loading to Mt Hood on Monday with potentially deep new storm slab and wind slab. Back country travel is not recommended above and near treeline at Mt Hood on Monday.
Terrain anchors are still causing some anchoring at the lowest elevations. Use caution near creeks which are still open in some areas at the lowest elevations.
Snowpack Discussion
Rain was seen to about 7000 feet at Mt Hood on December 17th. This has been followed by about 1.5 feet of snow the past 2-4 days.
NWAC pro observer Laura Green visited the Heather and Newton Canyon areas on Thursday and reported rapidly changing conditions with plentiful cracking and natural or easy to trigger heavy storm slab of 20-25 cm.
Widespread storm slab avalanches were also seen Thursday by the Mt Hood Meadows pro patrol with widespread sensitive and sympathetic storm slab of 8-12 inches.
Storm slab layers stabilized somewhat on Saturday. However the Mt Hood Meadows pro patrol reports increasing new 6-8 inch storm slab on east slopes on Sunday releasing on the crust from December 17th.
Avalanche Problems
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: Very Likely
Expected Size: 1 - 2
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, Treeline.
Likelihood: Very Likely
Expected Size: 1 - 2