Avalanche Forecast

Yet another atmospheric river is slamming the Mt Hood area Wednesday, bringing stormy wet weather with rising snow levels through Wednesday night.

The heavy precipitation at rising freezing levels should produce one or more natural avalanche cycles during the warmest periods, mainly Wednesday night. 

By Thursday morning, cooling and light to moderate showers with continued strong winds are expected. 

The cooling should help wet snow to begin consolidating and cause a lowering danger during the day with shallow new snow accumulations expected. 

However, near and above treeline, very strong winds should build new areas of wind slab on a variety of aspects, but mainly on NW-E facing slopes below ridges. 

Be especially aware that new shallow lower density snow may mask earlier storm slab formations, especially on slopes that did not avalanche late Wednesday or overnight Wednesday. 

Weather and Snowpack

Last week was wet and relatively mild with a series of active fronts transiting the region resulting in fluctuating freezing levels and periods of very strong winds (100+ mph gusts were not uncommon at the Mt Hood Meadows Cascade Express station).

The latter half of last week and the weekend featured more rain than snow at NWAC sites on Mt. Hood. For perspective, the averaged freezing level measured in March thus far has been 6600 feet at Salem; more akin to spring than late winter. 

A front Sunday and a cooler upper trough Monday brought some snow with 2 day storm totals of about 8-9 inches at Mt Hood ending Tuesday morning.

A very strong storm arrived Wednesday morning bringing heavy snowfall/rain at rising temperatures and very strong S-SW ridgetop winds.

The mid and lower snow pack at Mt Hood should be a stable mix of crusts and layers of moist and rounded snow crystals.

Recent Observations

On Saturday the Mt. Hood Meadows pro-patrol reported wet snow up to about 6600 feet with a thin crust above and a well consolidated snowpack in their area. Following the cool down Saturday night, pockets of shallow new wind slab were seen above treeline by Sunday morning. 

On Monday there was about 5 inches of new snow and the Mt Hood Meadows pro-patrol reported a variety of conditions including isolated hard 12-18 inch wind slab on ENE slopes above treeline, wide spread sensitive 4-8 inch storm slab near treeline and small ski triggered loose wet avalanches below treeline on solar slopes.

The Mt Hood Meadows pro-patrol found that new and recent storm snow layers were less sensitive on Tuesday and that cooling had stabilized previous loose wet snow. Direct back country observations were not made on Tuesday but areas of 4-6 inch wind slab were still expected there.

Quickly, Wednesday morning, new extensive wind slabs were forming on lee slopes near and above treeline. Explosive control Wednesday produced widespread slab releases on wind loaded N-NE facing terrain with crown depths of 2 feet common. 

Storm slabs Wednesday morning changed to loose-wet avalanches by midday as temperatures rose and snow changed to rain below treeline.