Archived

Avalanche Forecast

Nov 23rd, 2017–Nov 24th, 2017

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

Alpine

4: High

The avalanche danger rating in the alpine will be high

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

Regions: Lizard-Flathead.

If the rain-soaked snow freezes as expected through Friday and Saturday, avalanche hazard will follow a decreasing trend until the next storm on Sunday. Please treat this forecast as an initial assessment, as we have little information at this time.

Confidence

Low - Due to the number of field observations

Weather Forecast

Friday: Mostly dry with freezing levels around 1500 m. Moderate southwesterly winds becoming light in the afternoon.Saturday: Dry. Freezing levels initially around 1500 m, but increasing later in the day. Light southwesterly winds, increasing in the afternoon.Sunday: 15-20 mm precipitation, starting as snow at treeline elevations, then turning to rain. Freezing level rising to around 2200 m. Strong southwesterly winds.

Avalanche Summary

Storm slab avalanches were observed early this week and I'm certain that avalanches would have been triggered by the onset of the rain. Whether avalanches are still running is a different question and unfortunately the weather and lack of observers is making that hard to determine. I'd expect a decrease in avalanche activity with cooling temperatures into Friday and Saturday.

Snowpack Summary

Rain and warm weather have resulted in a widespread wet upper snowpack. The freezing level rose to close to 3000 m on Wednesday and Thursday meaning very few places, if any, will have escaped the melt. The last 48 hours have seen the snowpack diminish by approximately 10 cm. Expect treeline snow depths of around 90 cm. A crust that formed around Halloween has been reported from neighboring regions and probably exists in the Lizard-Flathead region too around 50 cm below the surface.

Avalanche Problems

Wind Slabs

Wind slabs may start to form at higher elevations in response to new snow and wind.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Loose Wet

Recent rain, snow and wind may still present storm slab problems, particularly if the snow surface has not hardened into a crust.

Start with lower angle slopes before gradually working up to steeper objectives.A crust on the surface will help bind the snow together, but may make for tough travel conditions.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2