Avalanche Forecast

Sunny weather should continue to Monday morning. High clouds should be seen by Monday afternoon mainly in the Olympics and south Cascades. There should be little change in snow conditions.

Concerns again on Monday should be very limited. Small areas of slab layers may linger on some lee shaded slopes mainly near or above treeline. Such layers would likely require large triggers such as a fall cornice or snowmobile. Use normal caution on steep lee shaded slopes.

Wet loose avalanches also seem unlikely on Monday due to recent consolidation, past activity and increasing high clouds. But avoid steep solar aspects or gullies in the sun if you seen natural wet loose avalanches or wet surface snow deeper than a few inches.

The last storm cycle to impact the Northwest was long ago about 10-14 of January. This produced a storm slab avalanches cycle about 12 January and large wet loose avalanches about 14 January with avalanches ranging up to size D3.  

But mostly sunny weather and warm temperatures have been seen the past 11 days. This has caused snow pack consolidation and stabilizing with surface crusts on most slopes in most of the area. A generally favorable mid and lower snowpack of crust layers and melt form crystals should also be seen in most of the area. The avalanche danger is especially low on many south slopes and at lower elevations where there is little snow and ample terrain and vegetation anchors. There have been no significant avalanches reported for about a week or more.

Small areas of cold slab layers are still apparently surviving on some lee shaded slopes where some faceting has been occurring in the upper snowpack.  NWAC observers at Hurricane and Nason Ridge near Stevens Pass the past several days are reporting moderate or hard test results with sudden collapse or sudden planar fractures (see photos below). But extended column tests have not indicated a tendency for propagation. These layers would also likely require large triggers such as a cornice or a snow mobile. There have been no known avalanches on these layers but we will continue to monitor them in case future changes or loading activate the layers.

Surface hoar growth has been reported this week especially east of the crest and will need to be watched in case it is buried by future snowfall.

ECTP29 SC Q1 at 67 cm due to crust and facet layers, Nason Ridge. NWAC observer Tom Curtis, 20 January.

Faceted crystals from the upper snow pack, Klahhane Ridge near Hurricane Ridge, NWAC observer Katy Reid, 20 January.

Quite a difference on north and south slopes, Klahhane Ridge, Olympics, NWAC observer Katy Reid, 18 January.

Report of the cornice/avalanche fatality on Lewis Peak on 18 January available at:

https://www.nwac.us/accidents/accident-reports/ 

Local non-avalanche hazards:  On 13 January a heavy local freezing rain event occurred in the Snoqualmie Pass area above about 4500 feet, covering the surface with about a 2-3 inch ice crust.  This crust should break down over time but a fall on a slope on this surface could result in a long and dangerous ride!

Additionally, guides in the North Cascades have noted some thin crevasse bridges on lower glaciers. Don't assume that crevasses have the usual relatively thick bridges during this so far shallow snow season.