Avalanche Forecast

Issued: Apr 11th, 2019 4:18PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Loose Wet.

swerner, Avalanche Canada

Lizard-Flathead.

The region has received variable storm snow amounts. In areas where 15 cm or more fell you may find reactive wind slabs on northerly aspects in the alpine. Daytime warming and periods of sun will likely trigger loose wet avalanches on solar aspects.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

An unstable airmass is mostly responsible for the continued spring-like (unsettled) weather conditions. Flurries and periods of cloud and sunshine will persist through the forecast period. The convective nature and model disagreement makes it very hard to nail down snowfall amounts.FRIDAY: Mix of sun and cloud with a chance of flurries in the afternoon. Alpine temperatures near 3 degrees and freezing levels 1900 m. Ridgetop winds light-moderate from the southwest.SATURDAY: Cloudy with snow amounts 5-10 cm. Alpine temperatures near -1 and freezing levels 1500 m. Ridgetop winds strong from the southwest.SUNDAY: Mostly cloudy with flurries and gusty winds. Alpine temperatures near -2 and freezing levels 1800 m.

Avalanche Summary

On Thursday, explosive control was able to initiate a few loose dry avalanches up to size 1.5 which failed in the recent storm snow. In the afternoon skier controlled loose wet avalanches were easily triggered at treeline and below up to size 1.5 on sunny aspects. No natural avalanche activity was reported and no new avalanches were noted in alpine elevations. Its important to make observations with changing conditions through the day and know when to pull back or dive into your line. If you're unsure, its best to have a conservative approach.

Snowpack Summary

15 cm overnight brings 20-35 cm of recent accumulated snow since last weekend which sits above a supportive crust at treeline and in the alpine. During the heat of the day, especially under direct sun, the snow surface becomes moist or wet almost everywhere. The exception being high elevation north facing features. Steep, north facing, alpine terrain may still hold a cold, dry, snowpack where isolated reactive wind slabs may exist and a well settled slab rests on weak facets (sugary snow). Although unlikely, human triggering of persistent slabs on this layer may still be possible, especially in rocky alpine terrain with a shallow or highly variable depth snowpack. Below treeline the snowpack is becoming isothermal.

Problems

Wind Slabs

Wind slabs may exist on higher elevation North facing slopes and may be reactive to human triggers.

Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.Be alert to changing conditions and avalanche problems with aspect and elevation.

Aspects: North, North East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

The likelihood of loose avalanches increases as temperatures warm through the day and/or if the sun comes out for period of time.

Loose avalanches may start small but they can grow and push you into dangerous terrain traps.A moist/wet snow surface, pinwheeling and natural avalanches all indicate a weakening snowpack.

Aspects: East, South East, South, South West, West.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

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