Avalanche Forecast

Wednesday will be a transition day with lighter winds, some scattered light showers over the west slopes of the Cascades and Mt Hood, and slightly warmer temperatures. There will be strong sun effects through clouds if not direct sun at times in this area. More sun is likely over the Olympics and along the Cascade east slopes.

Wednesday will also be a day of transition from winter-like avalanche problems such as wind slab and storm slab to solar driven loose wet or possible wet slab avalanches. Strong spring direct sun or sun effects through clouds can rapidly make new snow sensitive and underlying frozen previously sun affected firm snow can provide good smooth bed surfaces - this includes ski runs at closed ski areas.

Conditions will be the most dangerous on Wednesday in the areas with significant storm snow - say more than about 6 inches. In general the heaviest storm snow has been on the volcanoes especially Mt Hood where large or very large avalanches are likely. Very dangerous avalanche conditions are expected and backcountry travel in avalanche terrain is not recommended in these areas on Wednesday. Avoid all avalanche terrain at Mt Hood.

Careful snowpack evaluation and cautious routefinding will be essential and shallower storm snow will still likely be sensitive to triggering in other areas.

Due to stronger winds and heavier snow, conditions are likely to more dangerous above the crest level on the volcanoes.

Looking further out, with all the snow the past couple days, warmer weather and strong spring sun or sun effects there is likely to be a spring avalanche cycle in backcountry areas the next few days. More special statements for spring avalanche conditions are likely later this week.

Say goodbye to winter...but hello to spring avalanches!

The weather will finally shift from the winter-like pattern so far this spring to a fair weather pattern this week. Due to the heavy snow the past couple days, warmer weather and strong spring sun or sun effects through clouds we should expect a spring avalanche cycle to begin on Wednesday which may last a few days. There should be an avalanche cycle in backcountry areas with the heaviest storm snow especially on the volcanoes.

On Monday night in advance of the front there was increasing moderate southwest alpine winds and increasing moderate to heavy rain or snow near and west of the crest with lowering snow levels.

Then a strong late season front crossed the Northwest on Tuesday morning. An upper low pressure system and cold, unstable air mass is following and moving southeast over Washington on Tuesday. The strongest winds have been in the south Cascades and especially Mt Hood. Snow levels on Tuesday have bumped up a little due to afternoon warming to the 4-5000 foot range in most areas but are a little lower at Mt Hood.

Communications to the base weather station are out at Mt Baker likely due to lightning on May 4th. But the ski area crew there today reported about 15 inches of storm snow.

The only recent backcountry report comes via the NWAC Observations page from Washington Pass on Tuesday where skiers reported 5-8 inches of storm snow that was not well bonded to the previous frozen sun affected snow. On south slopes they triggered several storm slab avalanches that gave debris piles 4 ft deep x 150 ft wide.

Storm snowfall for the 2 days ending Wednesday morning is about 4-6 inches at Hurricane, 6-23 inches along the west slopes of the Washington Cascades with the most on the volcanoes and generally above the pass levels, about 20-40 inches at Mt Hood, and perhaps about 4-8 inches along the Cascade east slopes at higher elevations. This is a lot of snow for this time of year especially at Mt Hood.