Avalanche Forecast

Issued: Mar 15th, 2019 3:40PM

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

jleblanc, Avalanche Canada

Kootenay Boundary.

As temperatures continue to warm, pay particular attention to slopes that are being affected by the sun.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

FRIDAY NIGHT: Cloudy with clear periods. Alpine low temperature -5C. Light west winds at ridgetops.SATURDAY: Cloudy with sunny periods. Alpine temperature reaching -2C. Light west winds at ridgetops. Freezing level between 1800m - 2000m.SUNDAY: Mix of sun and clouds. Alpine temperature around 0C. Light west winds at ridgetops. Freezing level between 2000m - 2300m. No overnight freeze expected.MONDAY: Mainly sunny. Alpine high temperature +4C.Light west winds at ridgetops. Freezing level between 2500m - 2800m. No overnight freeze expected.

Avalanche Summary

Numerous small (up to size 1.5) wind slabs were triggered by skiers on Thursday on various lee aspects at treeline and above. The sun has already affected the snow on steep south-facing slopes and triggered small loose wet avalanches at lower elevations. Natural and human triggered loose wet avalanches are likely with tomorrow's strong sun and steadily rising freezing level.

Snowpack Summary

In the last week 25-40 cm of storm snow has fallen which is becoming moist on aspects that have seen the strong March sun. Recent winds have switched from north to west to south leaving wind affected snow on a variety of aspects, especially on features near ridgetops and open areas at treeline. Various surfaces are hidden under the recent storm snow such as sun crusts on southerly slopes, hard wind-affected snow in exposed locations and soft faceted snow in sheltered areas.Two weak layers that mainly consist of surface hoar are buried in the snowpack between 55 and 90 cm deep, these were buried in mid-February and early-February. The layers may be associated with a melt-freeze crust on southerly aspects. Although no recent avalanche activity has been reported on these layers, they may become a concern as the warming progresses.

Problems

Wind Slabs

Wind slabs will remain reactive, particularly on south-facing slopes that are affected by the sun.

Be careful with wind loaded pockets, particularly near ridge crests and roll-overs.Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.The best powder will be found in sheltered locations on northerly slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

The recent snow will quickly get destabilized as the sun affects it for the first time. This problem will likely be encountered in the afternoon hours.

Use caution on sunny steep slopes, if the snow becomes moist or wet.Rock outcrops will heat faster with the strong March sun.Loose wet sluffs may begin small but can grow big and push you into dangerous terrain

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 1.5

Valid until: Mar 16th, 2019 2:00PM