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Mt Hood

Issued: 7:59 PM PST Monday, March 5, 2018
by Dennis D'Amico

NWAC avalanche forecasts apply to backcountry avalanche terrain in the Olympics, Washington Cascades and Mt Hood area. These forecasts do not apply to developed ski areas, avalanche terrain affecting highways and higher terrain on the volcanic peaks above the Cascade crest level.

It is still possible to trigger large and destructive avalanches in wind-loaded, steep, open slopes at upper elevations. Stay off of open, obvious wind loaded terrain steeper than 35 degrees and allow recent wind layers time to heal. Small loose wet avalanches will be found at all elevations on steeper terrain exposed to direct sunshine. Avoid steep, sun-affected slopes later in the morning.

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Avalanche Problems for Tuesday

Wind Slabi

Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.

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Loose Weti

Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.

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Forecast for Tuesday:

Tuesday's weather forecast calls for mostly sunny skies with the potential for cumulus clouds to develop in the afternoon with rising freezing levels.

It may be possible to still trigger a large and dangerous older wind slab avalanches above treeline especially on leeward northwest through north through southeast slopes where drifted wind features exist. These avalanches could be large and destructive if triggered, but these older wind slabs should be trending toward unreactive. Watch for small, fresher wind slabs on mostly easterly aspects near and above treeline. Avoid these avalanches by staying off of snow drifts, deeply pillowed features, and fresh cornices on leeward slopes 35 degrees and steeper.

Expect natural and human-triggered small loose wet avalanches are likely to release within the recent 3" of surface snow on steep slopes on the south half of the compass as the sun impacts the surface snow to higher elevations. Watch for moist snow conditions and roller balls as a sign that these avalanches may for and avoid steep sunny slopes, particularly where a small avalanche may push you into a terrain trap, rocks trees.

Avalanche Summary:

Mt. Hood received 3" of new snow by Monday morning and west winds were transporting snow onto lee slopes (mostly easterly aspects) forming shallow wind slabs about 8" deep that were not particularly reactive. The sun also came out on Monday, warming snow on sun-exposed aspects and creating small loose wet avalanches below treeline.

A few inches of snow fell during the day Thursday, followed on the heels of about 8-10 inches of snow that was deposited Wednesday night through Thursday morning. Strong, mostly SSW winds accompanied Wednesday night's snowfall. A variety of snow conditions exist within the upper snowpack, ranging from sandwiches of soft snow with several crusts on shaded aspects with a multitude of crusts existing on sun-exposed aspects. Wind affected snow and unconsolidated surface snow can be found in shaded sheltered areas.

In many locations more than 3’ of snow now sits on a firm buried crust layer (2/17). This crust has been reported up to 6600’ by professionals in the region. There are currently no significant layers of concern below the 2/17 crust.

Observations

On Monday, Mt. Hood Meadows Pro Patrol reported west winds transporting snow, 20 cm of new and generally non-reactive wind slab on lee aspects limited to E facing slopes. Winds eased mid-day. Small loose wet avalanches occurred on solar, especially below treeline.

On Sunday, an avalanche professional reported no avalanches and no cracking or whumphing observed in the Salmon River Canyon. A test pit at 6200' on a NE aspect indicated right-side up, low-density snow in the upper 12" of snow, with a very thin rimed crust in the upper snowpack and a 1-2 cm more significant crust down 1.5'. A compression test indicated moderate reactivity on this layer.

On Saturday, Mt. Hood Meadows ski patrol reported no new avalanche activity other than small loose wet avalanches on steep solar aspects below treeline. 

No Corresponding Mountain Weather Forecast Available

USE AT YOUR OWN RISK

This Backcountry Avalanche Forecast is provided in conjunction with the US Forest Service, and is intended for personal and recreational purposes only. Safe backcountry travel requires preparation and planning, and this information may be used for planning purposes but does not provide all the information necessary for backcountry travel. Advanced avalanche education is strongly encouraged.

The user acknowledges that it is impossible to accurately predict natural events such as avalanches in every instance, and the accuracy or reliability of the data provided here is not guaranteed in any way. This forecast describes general avalanche conditions and local variations will always occur. This forecast expires 24 hours after the posted time unless noted otherwise.