Avalanche Forecast

Issued: Jan 11th, 2019 4:16PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Deep Persistent Slabs.

kdevine, Avalanche Canada

Lizard-Flathead.

A big rise in freezing levels may mean that a deep persistent slab wakes up. A lot of uncertainty exists as to what this layer will do as temperatures climb. High levels of uncertainty are best managed by choosing conservative terrain.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Exact freezing levels and alpine temperatures are difficult to forecast in the coming days with mild temperatures and temperature inversions dominating the weather pattern this weekend.FRIDAY NIGHT - Mainly cloudy / southwest winds, 10-20 km/h / alpine low temperature near -4 / alpine temperature inversionSATURDAY - Cloudy with sunny periods / southwest winds, 10-20 km/h / alpine high temperature near +3 / Freezing level 1500 m / strong alpine temperature inversion with above freezing temperatures possible to 3000 mSUNDAY - A mix of sun and cloud / southwest winds, 10-20 km/h / alpine high temperature near +5 / freezing level 3000 m / strong alpine temperature inversionMONDAY - Sunny with cloudy periods / southwest winds, 10-20 km/h / alpine high temperature near +5 / freezing level 3000 m / strong alpine temperature inversion

Avalanche Summary

Several explosives triggered avalanches to size 2.5 were reported in the region on Friday. Most of these were on northerly aspects in the alpine. One was on a southeast aspect at 2000 m.Several explosives triggered avalanches to size 2 were reported on southeast and northeast aspects between 1850 m and 2100 m on Thursday.A size 1.5 natural storm slab avalanche was reported on Wednesday.

Snowpack Summary

15-30 cm of recent new snow combined with mild temperatures and strong winds has formed storm slabs at alpine and treeline elevations. The snow surface has likely frozen into a melt freeze crust below 1600 m, and a sun crust at upper elvations. The new snow sits on previous storm snow and wind slabs above 1500 m, and a melt freeze crust below 1500 m.In sheltered areas around treeline, 70-120cm of recent snow may sit on a weak layer of surface hoar (feathery crystals). In the east of the region near Corbin, a persistent weak layer that formed in early December may still be found 90 to 150 cm deep. This layer mostly consists of faceted (sugary) snow with some isolated areas also containing surface hoar. While professionals are still tracking this layer, it has not been reactive for some time now.There is a mix of crusts and facets that formed in late October/early November near the bottom of the snowpack. This layer may only be an issue on steep slopes where the snowpack is shallow.The deeper layers in the snowpack may become reactive this weekend with warm temperatures and sun impacting the snow.

Problems

Storm Slabs

Up to 30 cm of recent snow has formed a storm slab which may become more reactive with rising temperatures and sun affecting the snow, especially in wind loaded areas.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Be cautious as you transition into wind affected terrain.Extra caution needed around cornices with current conditions.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Deep Persistent Slabs

A deeply buried weak layer may wake up with rising freezing levels and sun affecting the snowpack . Large triggers like cornices may cause avalanches on this layer, and cornice failures become more likely during warm, sunny conditions.

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. Minimize exposure to steep slopes on warm or sunny days.Pay attention to overhead hazards like cornices which easily trigger the deep persistent slab.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1.5 - 3

Valid until: Jan 12th, 2019 2:00PM