Avalanche Forecast

Issued: Mar 12th, 2015 4:52PM

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

jon stuart-smith, Parks Canada

Waterton Lakes.

Watch heating on Friday especially on solar slopes. Saturday 25 mm of rain is forecast to start in the afternoon but timing is uncertain. If this arrives the avalanche danger will increase as predicted in this bulletin.

Summary

Weather Forecast

Friday will continue the spring like warm trend. Freezing level will be above mountain top with sunny periods. A big storm is forecast to arrive on Saturday midday with up to 25mm of rain to mountain top and strong SW winds. Sunday will cool down as the storm passes with freezing back down to 1800m.

Snowpack Summary

The surface snow is now moist up to 2200m with no overnight freezing. Below 1900m the whole snowpack is becoming isothermal, especially on solar slopes. Hard windslabs are in N and E start zones in the alpine and upper treeline. Shaded areas are heavily wind effected down to treeline. The snowpack is becoming quite shallow at Cameron Lake level.

Avalanche Summary

There has been continued snowballing and sluffing out of exposed rocky areas in sun exposed slopes with the warm temperatures and daytime heating. Otherwise there has been no new avalanche activity in the last couple of days.

Confidence

Intensity of incoming weather systems is uncertain on Saturday

Problems

Loose Wet

Watch for sluffing to start out of exposed rocky areas where the suns heat has more impact. Limit your travel in steep exposed slopes during Friday. Rain forecast for Sat will increase the likelihood of wet slides in saturated snow.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Wind Slabs

These slabs are a concern on shaded NE areas at treeline and above. Rain forecast for Sat will make these slabs more unstable and increase the avalanche danger. If these become rain soaked these could act as a wet slab avalanche.

Be cautious as you transition into wind affected terrain.Avoid avalanche terrain during periods of rain.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

These layers from early season are still a concern on N aspects in the alpine, especially in shallow snowpack areas. Warm temperatures and rain penetrating the snowpack could wake up these deep instabilities.

Avoid shallow snowpack areas where triggering is more likely.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Mar 15th, 2015 4:00PM