Avalanche Forecast
Dec 31st, 2018–Jan 1st, 2019
Alpine
2:
Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2:
Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1:
Low
The avalanche danger rating below treeline will be low
Alpine
2:
Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2:
Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1:
Low
The avalanche danger rating below treeline will be low
Regions: Mt Hood.
The bottom line: Happy New Year! New Year's Day proves to be glorious sunshine but watch for recently formed wind slabs at higher elevations, especially near ridges. These wind slabs are healing but it may still be possible to trigger an avalanche on steeper wind-loaded slopes. Wind slabs at lower elevations will be harder to trigger but still possible on the right steep open slope or in a recently cross-loaded gully.
Avalanche and Snowpack Discussion
Following rain and freezing rain Saturday, 10-12 inches of snow accumulated Saturday night and Sunday with strong west to northwest winds slowly easing during the day on Sunday. Mt. Hood Pro-patrol found fresh but stubborn wind slabs up to 2' deep near treeline. More importantly, wind slabs had developed on unusual aspects, cross-loaded slopes and formed on open slopes below treeline. Winds had scoured ridges to the most recent firm icy crust in many areas. We have no recent observations from above treeline due to the recent stormy conditions.
Weather Forecast
Weather Synopsis for Tuesday night through Thursday
High clouds are moving into the forecast area on New Year's Day as an upper ridge flattens along the coast. The ridge will weaken further overnight allowing increasing frontal moisture to arrive in the form of thickening clouds. A shift to light westerly flow Tuesday has allowed warming temperatures under the ridge.
A cloudy day is in store for Wednesday as an offshore frontal system nears the coast. Some very light precipitation may reach the Olympics and Mt Baker area by late Wednesday afternoon.
Frontal precipitation will increase overnight Wednesday, mainly light in all areas except the Mt Baker area where significantly heavier precipitation is expected at rising freezing levels.
Moderate to heavy precipitation will spread over the area Thursday with a sharp delineation in intensities from north to south. Mt Baker area will receive heavy precipitation with only very light precipitation making its way to the Mt Hood area. Freezing levels should be at maximum levels Thursday morning before beginning to lower Thursday afternoon in the wake of a frontal passage.
It currently does not look like the easterly winds through the passes will be strong enough to save the passes from another rain event Thursday.
Avalanche Problems
Wind Slabs
Wind slabs formed over the weekend are gaining strength, but have not fully healed. Backcountry travelers and local professionals reported finding wind slabs in unusual locations such as low on the slope and in areas often wind-stripped. You may still trigger wind slabs on convex rollovers, near the sides of cross-loaded gullies, and on wind drifted snow well below ridgeline. In some locations, wind drifted snow may sit over a layer of buried surface hoar. In these locations, an avalanche may propagate widely and surprise you by extending long distances.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 2 - 2