Avalanche Forecast
Issued: Jan 21st, 2020 10:00AM
The alpine rating is , the treeline rating is , and the below treeline rating is
NWAC,
Northwest Avalanche Center
New snow and wind arriving Tuesday night and Wednesday will increase the avalanche hazard. Look for changing conditions throughout the day as heavy snowfall increases and temperatures rise. Stay clear of steep, lee slopes rapidly accumulating more snow than the surrounding slopes. At lower elevations, a change from snow to rain may make the snowpack especially unstable in the afternoon.
Summary
Discussion
New snow will start to stack up Tuesday night and will fall on a melt-freeze crust that is widespread. It remains to be seen how well new snow will bond to the crust or if sensitive weak layers develop during tonight’s snowfall. Investigate the bond between new snow and the crust below using small test slopes. Look for signs that you could trigger avalanches in the storm snow like heavy snow above light snow, or cracks shooting through the snow. Late morning or early afternoon, as the warm-up begins, will be the most likely time to trigger a storm slab on slopes steeper than 35 degrees on any aspect.
Near and above treeline and especially near the cascade crest, winds will be strong enough to rapidly build fresh and sensitive wind slabs on lee aspects. Wind slabs will build above the recent melt-freeze crust and may become large quickly. Look for blowing snow, fresh cornice development and cracks in the snow as signs that you could trigger an avalanche on similar slopes. Avoid leeward slopes steeper than 35 degrees especially midday as the temperatures rise.
As temperatures rise late Wednesday and snow eventually turns to rain below 5500’, loose wet avalanches will be easy to trigger. Pay close attention to signs of warming, such as rollerballs of snow, many trees beginning to shed snow or drip water. When you see these signs avoid slopes steeper than 35 degrees, especially when near cliffs, creeks and other terrain traps. Remember that loose wet avalanches are often surprisingly powerful and being caught in even a small on can be dangerous.
Choosing lower angled slopes (less than 35 degrees) is the best way to avoid an avalanche, like this wet loose slide near Timberline Lodge, Mt Hood. Photo: Geoff Lodge 1-18-20
Forecast Schedule and No Rating definition
We do not have enough specific snowpack information to issue an avalanche hazard rating for the East South zone. However, even when No Rating is applied, applicable avalanche conditions and backcountry travel advice will be provided throughout the season - this forecast is updated every day, all winter long! When weather systems produce very dangerous avalanche conditions in adjacent zones, NWAC will issue an avalanche warning for this zone as well.
Snowpack Discussion
New Regional Synopsis coming soon. We update the Regional Synopsis every Thursday at 6 pm.
Valid until: Jan 22nd, 2020 10:00AM
