Avalanche Forecast

An upper ridge and surface high pressure should begin to strongly build west of the US west all the way to the Gulf of Alaska on Monday. Light snow showers on both sides of the crest should decrease and end on Monday. New snow at Mt Hood should be in the 5-10 inch range above about 5-6000 feet by Monday morning.

A mix of likely dangerous winter and spring avalanche conditions is likely persist at Mt Hood on Monday. The sun is getting much stronger and new snow will be reactive to solar effects.

Loose wet avalanches should be likely especially on solar slopes on Monday. Avoid avalanche terrain if you start seeing pinwheels or initial small natural loose wet avalanches. Be aware of terrain traps where even a small loose wet avalanche could have unintended consequences.

New wind slab of a foot or more is likely on lee slopes mainly in the near and above treeline on Monday. This is most likely on north to east slopes but possible on other aspects. Watch cracking and firmer or chalky wind transported snow. Remember that snow pits may not be helpful due to variability in the snowpack.

New storm slab layers may linger into Monday where there was rapidly accumulating snow for more than a few hours on Sunday. Pay special attention to slope convexities where storm slab is mostly likely to be triggered.

Cornices have grown large recently. Cornices can break much further back on ridges than expected and releases can be unpredictable during the spring.

Weather and Snowpack

Snow accumulations Wednesday to Friday following the last front varied based on elevation, with only a few inches below 5000 feet and about 8-10 inches at the Mt. Hood Meadows and Timberline stations. This snow was generally well-bonded to a moist crust buried March 22nd.

A strong front and upper short wave crossed the Northwest Sunday morning. This is being followed by a large upper trough and cool unstable air mass Sunday afternoon and evening.

Frequent March storms have built large cornices along ridges in many areas.

The mid and lower snowpack along the west slopes should generally be a stable mix of crusts and layers of moist and rounded snow crystals.

Recent Observations

The Mt Hood Meadows pro-patrol on Tuesday morning 3/22 found wind loaded pockets of mostly small wind slab 12-18 inches deep in the above tree line which were stubborn to release by skis. On Tuesday afternoon a recent natural cornice release was seen at about 7000 feet on Marmot Ridge which released a small pocket of wind slab.

By Wednesday morning, Meadows pro-patrol found dense wind slab above treeline and on lee slopes only affected by large explosives. Above treeline, satstrugi was widely sculpted into the snow surface with some icy surfaces on windward ridges.

Explosive control in the Meadows ski area on Thursday produced pockets of 1-1.5 wind slab in the near and above treeline.

NWAC pro-observer Laura Green was out in Newton Canyon on Friday and found that winds had plastered the latest snow down with conviction, with moderate compression tests in the new snow and hard compression tests at the 3/22 interface. Limited rollerballs were seen on solar slopes. A size 2 natural avalanche from a potential cornice release was seen in White River Canyon.

The Mt Hood Meadows patrol reported 4-6 inches of new snow so far on Sunday in the upper ski area.