Archived

Avalanche Forecast

Dec 30th, 2016–Jan 2nd, 2017

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

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: Waterton Lakes.

Deja Vu for Saturday - new snow is blown around, creating Wind Slabs lee to strong South-West winds. Sunday sees an Upslope switch, with new snow being reverse loaded by North-East winds. Watch for Wind Slabs on both sides of ridges Sunday onward.

Weather Forecast

Saturday: Increasing cloud cover, with Strong Westerly winds easing late afternoon . Temperatures steady around -10.Sunday: Overnight switch to cold North-East winds (Strong in the Alpine, Moderate at Treeline) brings heavy snowfall in the early hours, tapering through the day. -20 at treeline.Monday: Frigid, Moderate North-East winds, flurries.

Snowpack Summary

New snowfall will form Wind Slabs lee to Strong SW winds on Friday night, then again lee to NE winds during Sunday. These cover hard Persistent Slabs, over facets in the middle and bottom of the snowpack. The distribution and sensitivity of these varies greatly, even across each slope. The snowpack is weakest in shallow and/or wind exposed areas.

Avalanche Summary

On Tuesday/Weds, shooting cracks and whoomphing were observed Below Treeline. One large avalanche noted from an Alpine lee slope.On Friday, several small Storm Slab and Wind Slab avalanches were observed in new storm snow, primarily on North and East aspects, at Treeline and Alpine elevations.Natural activity is possible on lee slopes Sat-Sun.

Confidence

Forecast snowfall amounts are uncertain on Sunday

Avalanche Problems

Wind Slabs

These will be found on North and East aspects on Saturday, with lots of recent snow available as fetch. The main problem will move to immediate lees on South and West aspects on Sunday and Monday, as wind directions reverse to the North-East.

Use caution in lee areas. Wind loading could create slabs.Keep an eye out for reverse loading created by an upslope storm.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

Nearby areas have seen these failing in the midpack facets in thicker areas and in loose sugary facets near the ground in thinner areas. They are most likely to be triggered in thin rocky areas, with variable snowpack depth.

Be aware of thin areas that may propogate to deeper instabilites.Good group management is essential to manage current conditions safely.

Aspects: North, North East, East, South East, South.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3