Archived

Avalanche Forecast

Nov 30th, 2018–Dec 1st, 2018

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

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Lizard-Flathead.

With few field observations, uncertainty exists around the buried weak layers in the snowpack. Natural avalanche hazard has tapered off but human triggers are still possible. Check out the new forecaster BLOG which expresses these uncertainties.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Mostly cloudy skies, cooling temperatures and dry conditions moving into the weekend. SATURDAY: Mostly cloudy with a trace of new snow/ alpine temperatures near -3/ generally light winds from the northeast/ freezing level 1300 mSUNDAY: Cloudy with a trace of new snow/ alpine temperatures near -6/ ridgetop winds light from the northeast/ freezing levels 1000 mMONDAY: Cloudy with sunny periods/ alpine temperatures -11/ ridgetop winds light from the northeast/ freezing levels valley bottom

Avalanche Summary

No new reports on Friday. Several storm slabs were initiated by explosives up to size 1.5 on Thursday. Even though the avalanche hazard has decreased I suspect human triggered avalanches will be possible. If you're in the backcountry and have observations to share, please post to the Mountain Information Network.

Snowpack Summary

The region received another 11 cm of snow overnight adding to the 35 cm of recent storm snow fell earlier this week. Recent south and southwest winds have formed pockets of wind slab on leeward terrain, however the winds have switched from a more northerly direction which are potentially redistributing the new snow. Below the surface exists a series of crusts and a spotty, feathery surface hoar layer. We have a lot of uncertainty around this weak layer and its hard to know where it actually exists and how reactive it is. If you were to find it, I suspect it could exist on sheltered slopes in the alpine and at treeline. Deeper in the snowpack a melt-freeze crust exists at treeline and into the alpine on all aspects. Little is known about this crust and how the snowpack above is bonding. I would investigate this bond before jumping onto large, planar terrain features. At the bottom of the snowpack you'll likely find melt-freeze crusts and sugary weak facet crystals. The snowpack is deepest in the alpine. At treeline the average snowpack depths are 80 cm. These depths taper rapidly at lower elevations.Check out the new forecaster blog post "The Buzz". Discussing uncertainty.

Avalanche Problems

Storm Slabs

Another 11 cm overnight adding to the storm slab. It may be reactive to human triggering, especially where they are stiffer from wind effect and/or sit above a weak interface like surface hoar or a crust.

Watch for signs of instability, such as whumphing, shooting cracks, and recent avalanches.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2