Avalanche Forecast
Regions: Mt Hood.
The avalanche danger is less than during the recent storm cycle but careful snowpack evaluation and cautious routefinding will still be essential on Tuesday.
Detailed Forecast
Light snow showers should end Tuesday morning. A clearing trend should develop by Tuesday afternoon. Winds should be pretty light Tuesday with cold temperatures.
The avalanche danger is less than during the recent storm cycle but careful snowpack evaluation and cautious routefinding will still be essential on Tuesday.
Wind slab should be most likely to linger on north to southeast aspects due to recent southwest flow aloft. But watch for firmer wind transported snow on other aspects.
Storm slabs in many areas that had r sustained heavy snowfall should further settle on Tuesday.
There is a confirmed persistent weak layer from about December 8th in the Washington Cascades from about December 8th. This type of layer is less common at Mt Hood and it won't be listed here as an avalanche problem. We don't have any snowpack observations identifying a persistent weak layer at Mt Hood. But ratchet back your plans if you experience deep cracking, collapsing or whoomping. Some time and snowpack tests from many areas will be needed to determine to what extent this layer is a regional problem.
Loose dry avalanches will not be listed as an avalanche problem on Tuesday. But in steep terrain lacking a slab structure continue to watch for small loose dry avalanches near terrain traps like cliff bands where even small avalanches can have big consequences.Â
With deep unconsolidated snow in many wind protected areas there remains a risk for tree well and snow immersion suffocation at this time. Ride or ski with a partner and keep them in sight at all times!
Even though the lower part of the below treeline band is filling in watch for early season travel hazards such as barely covered rocks and open creeks.
The regional avalanche danger is expected to further slightly decrease on Wednesday. But it is expected that southeast to east winds will transport snow and build new wind slab on Wednesday.
Snowpack Discussion
Weather and Snowpack
Cold and fair weather was seen early last week.
The latest storm cycle began about December 8th starting with a couple day warming trend as southwest flow eroded an Arctic air mass over the Northwest. The warming trend leveled off the past couple days. NWAC stations at Mt Hood had about 4 feet of snowfall for the 4 days ending Monday morning!
Recent Observations
A regional avalanche cycle was seen Friday and Saturday with some avalanches releasing on the December 8th layer.
The Mt Hood Meadows pro-patrol Sunday reported triggered soft slab avalanches were sensitive and releasing 6-12 inches in areas previously controlled. However, control work in Heather Canyon for the first time since the storms began Thursday also produced soft slabs with up to about 1 foot crowns. By Sunday afternoon slopes that had released early in the morning were already reloading and producing ski sensitive soft slabs up to about 6 inches.
The Mt Hood Meadows pro-patrol on Monday reported mostly cold stable powder including in non-previously skied terrain. Limited 12-18 inch storm slabs were found on N-NE Â slopes in teh 5500-6500 foot range.
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