Avalanche Forecast

Issued: Mar 14th, 2019 6:19PM

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

jleblanc, Avalanche Canada

Lizard-Flathead.

Storm slabs are the main concern, but it may be possible to trigger deeper weak layers with this upcoming warming.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

THURSDAY NIGHT: Cloud. Slight chance of flurries. Alpine temperatures low of -5C. Moderate north-west winds at ridgetops. FRIDAY: Isolated flurries in morning. Mix of sun and clouds. Alpine temperatures high of -2C. Light to moderate west winds.SATURDAY: Sunny with cloudy periods. Alpine temperatures high of -2C. Light to moderate west winds. Freezing level around 1600m to 1800m. SUNDAY: Sunny with cloudy periods. Alpine temperature high of +2C. Light to moderate west winds. Freezing level between 2000m and 2300m.

Avalanche Summary

On Thursday, a group of sledders remotely triggered a size 1.5 persistent slab after seeing many shooting crack and whumpfs. See the MIN report for more details. Wednesday, numerous storm slabs avalanches (size 1-2) were triggered by skiers on northerly aspects near ridgetops. Few larger loose dry avalanches (size 2-2.5) were also triggered by explosives on steep alpine slopes. Thursday, the sun has initiated several loose wet avalanches on solar aspects at treeline and above.

Snowpack Summary

Moist snow on the surface of sunny slopes. Up to 40 cm of recent storm snow overlies various surfaces such as old and firm wind slabs in the alpine and open areas at treeline on all aspects. A widespread sun/ temperature crust is also found hidden under this new snow on south facing slopes. Isolated pockets of surface hoar crystals were observed at the surface on north-facing slopes around 2000m right before this storm rolled in. The mid-snowpack consists of sugary faceted grains (facets) of different hardness. Two older layers of surface hoar still exist down 55-80 and down 95-150 around 1600-1900m. The lower snowpack is generally well-settled.

Problems

Storm Slabs

Recent new snow may still be reactive, especially where it is wind-affected. Watch also for slopes being impacted by the sun.

Be increasingly cautious on sun exposed slopes.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.The best powder will be found in sheltered locations at or below treeline.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

End of January surface hoar layer may be more reactive than expected, especially on slopes that are being affected by the strong March sun.

Be cautious in shallow snowpack areas where triggering a deeper is more likely.Warming could wake up a buried weak layer.Choose a low angle terrain without convexities or terrain traps.

Aspects: All aspects.

Elevations: Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2.5

Valid until: Mar 15th, 2019 2:00PM