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RegisterApr 21st, 2018–Apr 22nd, 2018
Mt Hood.
While generally safe avalanche conditions are expected Sunday, you can still trigger a small loose wet avalanche on steep sunny slopes or at lower elevations as the day warms. Look for signs of wet surface snow developing as you travel. Avoid slopes with terrain traps where even a small loose wet avalanche could have unintended consequences. Do not linger below slopes overhung by large cornices or where a cornice fall may trigger larger deeper avalanches.
Sunday should be a fair spring weather day with some building cumulus in the afternoon. Freezing levels should push to near or above 7000 feet after a cool start.
While generally safe avalanche conditions are expected Sunday, you can still trigger a small loose wet avalanche, especially on steep sunny slopes and at lower elevations as the day warms. Look for signs of wet surface snow developing as you travel. New rollerballs, fresh fan shaped avalanche debris, and wet surface snow deeper than your ankle all indicate the potential for loose wet avalanches has developed on similar steep slopes. Avoid slopes with terrain traps where even a small loose wet avalanche could have unintended consequences.
Wind slabs that formed on many slopes near and above treeline last week should be unreactive.
Cornices over the winter have grown very large. Do not linger below slopes overhung by large cornices or where a cornice fall may trigger larger deeper avalanches.
About an inch of new snow fell Saturday morning as a frontal system largely missed Mt. Hood and affected areas further north. Moderate west winds near and above treeline did not have any new snow to transport. No new avalanches were reported Saturday.
Warm and generally sunny weather affected the snow in the Mt Hood area Thursday and Friday. On slopes receiving sunshine and on lower elevation slopes, moist surface snow conditions developed. The mild weather allowed wind slabs formed earlier in the week time to gain strength.
Significant snowfall accumulated in the Mt Hood area earlier in the week. Around 16-20 inches (40-50 cm) of snow fell Sunday (4/15) through Tuesday (4/17). Strong west-southwest winds during the storm transported the new snow forming wind slabs on many slopes at higher elevations.
While numerous layers can be found within the snowpack, there are no significant layers of concern at this time.
Observations
On Thurday, NWAC professional observer Laura Green traveled in the Mt Hood backcountry. Laura found wind slabs on NE-E aspects near treeline. These wind slabs were still reactive in some snowpack tests. On south-facing slopes, she observed large rollerballs up to 3 ft (90cm) in diameter.