Archived

Avalanche Forecast

Jan 13th, 2019–Jan 14th, 2019

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Cascades - East.

The Bottom Line: The avalanche danger will rise as the day warms up. Get off of steep, sunny slopes if you see rollerballs or find wet snow on the surface. Loose wet avalanche debris is heavy, and can pack a punch. Don't these slides ruin your day. There still remains an isolated chance of triggering a deeper slab on older weak layers.

Snow and Avalanche Discussion

Folks should realize that there is a fair amount of uncertainty with our snowpack and how the warming will influence it, particularly above 6,000ft. There is also a lot of variability within the zone. The current snow surface is a mixed bag. On sunny aspects, it is likely crusted over early in the morning, and becoming wet and heavy by mid day. The snow has been remaining cold and dry above 5,000ft on shaded aspects, and small surface hoar growth has been observed. The storm snow from January 8th and 9th sits over a crust from January 3rd. A thin layer of weaker snow has been found just above this crust, and is worth checking out how these are bonding. A round of control at Mission Ridge on the 10th pulled out a number of large wind slabs. One of these on a Northwest aspect at 6300ft broke through the crust and ran on weaker snow near the ground, exposing rocks. On steep southerly aspects, a number of loose wet avalanches have been observed.

Avalanche Problems

Loose Wet

With balmy temperatures on the mountain tops, and sun in the forecast, loose wet avalanche danger will increase as the day progresses. Steep slopes that face the sun are the most likely places these will happen. If you see roller balls, notice the surface crust is melting and becoming wet and heavy, or see small loose slides that begin entraining snow on any aspect, get off of steep slopes. These will be more of a concern above the cold air that is pooled at lower elevations.

Aspects: South East, South, South West.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 2

Wind Slabs

Be mindful of thin windslabs at the uppermost elevations where the wind may have drifted cold, dry snow into small wind slabs here and there. There are still some bigger slabs that were built during the east wind event on the 8th and 9th, but these are becoming more difficult to initiate. If you were to find one of these, it would likely be in more radical terrain. Be especially careful of steep, unsupported, and rocky slopes. Use visual clues, like snow surface texture to help you find where these areas may be. Wind slabs will often feel more firm than in non wind affected areas, and they may feel hollow underfoot. Ease into avalanche terrain by using smaller, inconsequential slopes first. Only expose one person at a time to any one particular slope.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely

Expected Size: 1 - 2

Persistent Slabs

Deeper avalanches in old snow have become less and less likely. However, the consequences are still high. Obvious clues to danger like shooting cracks and whumphs probably won’t be observed, although a weak snowpack structure still exists in some locations. These weak layers are slowly adjusting, but rapidly rising freezing levels and the sun are something to consider in that it may influence the reactivity of the slabs. In any case, slides on these deeper weak layers would be very large and surprising. You can minimize your risk by using lower angle, and well supported slopes, and staying out of radical terrain. Shallow, shaded, and rocky slopes are also good places to avoid.

Two primary layers of concern in the snowpack are:

A layer of buried surface hoar found 1-3 ft below the snow surface. This is mainly a concern above 6000ft. Be suspicious of this layer the higher you go. Documented avalanches have been on North through Southeast aspects. Snowpack tests continue to reveal sudden results in some areas on this layer.

A layer of weak, sugary facets can be found near the ground in the Wenatchee Mountains, and other areas on the eastern edge of the forecast zone. If an avalanche failed on this layer, it could be more than 4 feet deep. Use caution if you are traveling in areas where the snowpack is thinner, and where any stiff snow overlies weak snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely

Expected Size: 3 - 3