Avalanche Forecast

Heavy rain Saturday morning transitioned to snow by late Saturday afternoon following a strong frontal passage. Very strong winds and further snowfall in moderate showers will continue Saturday night and Sunday.

Continued winter-like stormy weather will create very dangerous avalanche conditions at mid and higher elevations by Sunday. The greatest impact of the current storm is affecting the volcanic peaks, including the Mt Hood area where the greatest precipitation and hence danger increase is expected.  

Wind Slabs will build on lee slopes and a variety of cross loaded terrain features, possibly well below ridges due to the strength of the winds where natural or triggered avalanches are likely to very likely. Use visual clues such as blowing snow, fresh Cornices, and cracks in the snow all indicating that you could trigger a Wind Slab avalanche.  

While the bonding of new snow to the old wet snow surface should be favorable, unstable Storm Slabs will build on a variety of steep terrain, especially in those areas receiving the greatest new snow amounts. Watch for deeper stiffened slabs developing Sunday on a variety of aspects.

Fresh Cornices are likely to build along ridges, so give Cornices a wide berth if traveling along ridgelines as they often break back further than expected. Be aware of overhead hazard if traveling on slopes with Cornices above as they may fail naturally or be human-triggered. 

A vigorous storm Saturday caused periods of heavy rain and warm temperatures early Saturday that transitioned to snow or wet heavy snow by Saturday afternoon with shallow new snow beginning to accumulate by Saturday afternoon. The old rain soaked snowpack has begun to refreeze and form a crust under continued cooling. New snow has fallen on rain wet surfaces on most slopes.

Periods of rain and a rising snowline allowed wet snow conditions to extend to near and above treeline Thursday and Friday.  A series of crusts and moist or wet snow exist in the upper snowpack.  

There are currently no significant layers of concern in the mid or lower snowpack.

Observations

NWAC professional observer Laura Green was in the Timberline area on Friday. She observed some natural pinwheels in the wet surface snow and small broken cornice chunks, but no recent avalanche activity of note. Snow surfaces were wet on all aspects and all elevations that she traveled on up to 6500'.