Avalanche Forecast

Issued: Mar 18th, 2019 4:56PM

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

swerner, Avalanche Canada

Sea To Sky.

Persistent warm temperatures are penetrating and destabilizing the upper snowpack. Natural avalanche activity is likely. Pay attention to sunny slopes and avoid travel under avalanche paths especially slopes with cornices overhead.

Summary

Confidence

Moderate -

Weather Forecast

Hot and sunny with freezing levels through the roof! Very little temperature driven overnight re-freeze is expected. TUESDAY: Mostly clear skies and freezing levels holding strong above 3100 m. Alpine temperatures near + 10.0 degrees with moderate southeast wind at ridgetop. Alpine temperatures may drop to + 4.0 degrees overnight.WEDNESDAY: Mix of sun and cloud with freezing levels above 2600 m. Alpine temperatures +7.0 degrees with light southeast ridgetop winds. Freezing levels may drop to 800 m overnight.THURSDAY: Cloudy periods. Alpine temperatures near + 7.0 degrees and freezing levels 2840 m during the day.

Avalanche Summary

With sunny skies and warming temperatures reports from region saw numerous natural loose wet avalanches from solar aspects up to size 2 in the alpine and at treeline. With continued warming we expect to see natural avalanche activity continue on all aspects and elevations.

Snowpack Summary

About 30 cm of snow has fallen in the last week. Towards the end of the last storm winds shifted to the north forming some unusual wind slabs on south-facing slopes. Beneath this more recent snow you may find hard wind-affected snow at higher elevations, soft faceted snow in shaded and sheltered areas, and crusts on steep southerly slopes. Currently, we're most concerned about the upper 30 to 50 cm of snow.The bigger questions are deeper in the snowpack. With little overnight re-freeze the warm temperatures will penetrate deeper allowing melt and a lot of water which will lubricate the upper snowpack. It also allows the upper snowpack to start creeping downhill at an accelerated rate. It’s hard to say how many hot days and warm nights it will it take to wake up the more deeply buried weak layers. We're not sure, but now is probably a time to let the mountains do their thing from afar and check back in when the freezing levels return to seasonal norms which could happen by next weekend.

Problems

Loose Wet

Loose wet activity is expected to continue on all aspects and elevations. Cornices are going to begin to loosen up and drop on the slopes below. You don't want to be under or near one of these monsters when they fail.

Loose avalanches may start small but they can grow and push you into dangerous terrain.Cornices become weak with daytime heating or solar exposure.Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Wind Slabs

A warm night followed by another day of clear skies and hot temperatures is expected to further destabilize the upper 30 to 50 cm of snow which has potential to fail naturally.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Back off slopes as the surface becomes moist or wet with rising temperatures.Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1.5 - 2.5

Valid until: Mar 19th, 2019 2:00PM