Avalanche Forecast
Regions: Mt Hood.
Caution, expect new wind deposited snow on unusual aspects, mainly near but especially above treeline. Watch for wind stiffened surface snow on a variety of aspects and avoid steep terrain with evidence of wind loading.
Detailed Forecast
Up to 12 inches of new snow accumulated from Wednesday afternoon through early Thursday morning. This new snow accumulated along with a slight warming trend and switch from east to west winds. Due to shifting winds over the last week, expect wind slab to be found on a variety of aspects above treeline.
Mostly fair weather with cold temperatures and light winds are expected Friday. The cold temperatures should slow the stabilization of recent wind deposited layers.
Older wind slab from the latest storm cycle should have mostly stabilized, but watch for firmer wind transported snow on all aspects mainly near and above treeline.
Storm slabs from the latest storm cycle have  stabilized in the Mt Hood area.
Loose dry avalanches remain possible on some steep terrain, protected from recent winds.Â
With deep unconsolidated snow in sheltered areas there remains a risk for tree well and snow immersion suffocation. When near trees, 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.
Snowpack Discussion
Weather and Snowpack
Cold and fair weather 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 with temperatures staying well below freezing December 10th and 11th and snowfall tapered off by December 12th. NWAC stations at Mt Hood had about 4 feet of snowfall for the 4 days ending Monday morning.
Fair weather Tuesday and Wednesday with a period of strong east winds Wednesday transported snow to unusual more westerly facing exposed terrain at higher elevations.Â
A weather system moved across the Mt Hood area beginning late Wednesday and deposited about a foot of new snow by Thursday morning, with winds shifting to moderate to locally strong westerly winds.
Recent Observations
A regional avalanche cycle was seen December 8th-11th.Â
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 the 5500-6500 foot range.
A report is available via the NWAC Observations tab for the Tilly Jane drainage on Monday. Deep but generally homogenous storm snow was indicated with very small wind slab on a N-NE slopes near a ridge line.
A report is also available for Monday via Turns All Year for the Barlow Snowpark area with good stability in the deep storm snow indicated.
By Tuesday the Mt Hood Meadows pro-patrol found only pockets of 1-2 foot wind slab on southeast slopes in the 6-7000 foot range with hand charges.
Following the most recent 12 inches of new snow Thursday morning, patrol at Mt Hood Meadows, indicated new wind slab was sensitive to ski trigger even on lower angled slopes. These avalanches, about 1 foot crowns, released above tree line on mainly E-NE facing terrain.
Near and below treeline, the unconsolidated new snow was well bonded to the old surface and no avalanches were noted, but ski conditions of excellent quality were noted! 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: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1