Avalanche Forecast

Deep storm snow and large wind slabs will require extra time to stabilize. This is a time to plan travel on lower angled terrain well away from avalanche paths or run out zones. Avoid large steep open slopes or terrain of consequence.

Light to moderate snow showers at cool temperatures are expected overnight and Monday. Winds should be moderate, but strong enough to easily transport loose surface snow, building some fresh wind slabs on lee exposed slopes.

Generally light accumulations of new snow are expected and with cold temperatures and light to moderate winds this should maintain the current level of avalanche danger. Cold temperatures may help maintain older wind slab layers near and above treeline.

Heightened avalanche conditions should persist in specific terrain near and above treeline Monday, mainly exposed steep slopes that have received wind transported snow.

Evaluate the snow and terrain carefully and avoid suspected wind loaded slopes. 

Cornices won't be listed? as an avalanche problem in this area, but avoid travel on ridges, where recent cornices may have formed and avoid steep slopes below cornices, that may fail at any time.

Weather and Snowpack 

The most recent warm, wet storm arrived on Valentines Day 2/14 forming a strong rain crust, now buried 2-5 feet or more in most areas along the west slope Cascade zones. 

A series of disturbances in cool, NW flow aloft from Saturday 2/25 through Tuesday 2/28 deposited 1.5 - 3.5 feet of snow along the west slopes of the Cascades. Very strong alpine west winds were seen in most of the Olympics and Cascades on Tuesday.

Strong southwest flow carried a strong front across the Northwest on Friday evening. Along the Cascade west slopes this caused strong southwest alpine winds, heavy, moist, dense new snow above about 3-4000 ft and wet snow or rain below about 3-4000 ft.

A widespread avalanche cycle occurred late Friday and Friday night in many areas along the Cascade west slopes.

Mt Baker area received over 2 feet of new snow as of Saturday morning, with an additional 8-12 inches by Saturday afternoon. Deep storm snow about 3 feet or more will take additional time to settle and stabilize. It remains time to pull back from traveling in steep terrain, and features of consequence. 

There was widespread natural and human triggered large avalanches reported in the Mt Baker backcountry from late Friday through Saturday. 

An additional 6-8 inches of new snow accumulated in showers Sunday with periods of moderate and gusty winds.

Significantly less recent storm snow fell in the central and south zones over the past few days and this has created somewhat less dangerous avalanche conditions than the Mt Baker area. 

Recent Observations

North

NWAC observer Lee Lazzara reported that extensive avalanche control was needed in the Mt Baker ski area on Friday but further detail are not currently available. Lee found an upside down warmer, wetter over drier, weaker profile and that test columns were failing on isolation in storm snow layers. A general top of the snowpack profile was 30-40 cm of 1F+ over 4F snow.

Lee was in the area Saturday and the previously seen layer of strong wet snow layer over weaker snow was down about 2 feet. Storm slabs were sensitive Saturday and as a result travel was confined to low angle slopes away from any terrain of consequence.  

Widespread 1-2 ft storm slabs and larger, 3-5 foot wind slabs were seen in the backcountry near Mt Baker, Saturday. A close call occurred Saturday on Mt Herman when a large wind slab was triggered, and partially burying two and fully burying one in a separate party at the base of the slide path after completing a run. It was a fortunate outcome with no significant injuries. NWAC will compile a report and post on the website as soon as possible.

The recent storm snow is DEEP in the north zone and should prompt a conservative approach to backcountry travel for more days.

Central

Dallas Glass was in the Alpental Valley Saturday and reported that previous moist to wet snow was settling and less reactive. The earlier storm slab problem was rapidly improving in this zone.

Dallas was back in the western Alpental Valley Sunday, from 3000-5500 ft and noted a recent natural cycle occurred, likely early Sunday during heavy snow shower intensities. Numerous 6-8 inch storm slabs released in steep terrain near and below treeline. There is significant low density surface snow available for transport, so watch for increased winds over the next few days.  

Wind slab, 1-2 feet, ski triggered Saturday, March 4th, while ascending the ridge, Arrowhead Peak, east of Stevens Pass, 5500 ft elevation, SW aspect., no skier involvement. Photo: K. Johnson

South

NWAC observer Jeremy Allyn was in the Crystal Mountain backcountry Sunday and reported a good profile of the recent storm snow of nearly 3 feet over the Valentives crust. No avalanches or reactive tests were noted when travelling on steep exposed terrain. Wind effects were minimal in this area, however, there was no exposure to terrain near ridges where wind slabs would be more likely. Fresh cornices were ample and when dropped, triggered shallow surface snow that failed to propagate or entrain significant snow.

Here is a nice photo example of the cornice features, captured Sunday in similar terrain, near Crown Point by our good friend Seth Waterfall, thanks. 

Crown Point,  Sensitive Cornice and Wind Slab, Sunday, March 5. Photo: Seth Waterfall