Avalanche Forecast

Issued: Mar 24th, 2014 7:55PM

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

Tim Haggarty, Parks Canada

Waterton Lakes.

Stay alert to the many changes in the snowpack that the weather will bring in the next few days. Conditions vary greatly with aspect and elevation.

Summary

Weather Forecast

Clear skies with high freezing level forecast for Tuesday. A series of systems that extends through the weekend beings with Light precipitation begins overnight Tuesday. Freezing levels reaching near 1700m Wednesday. Moderate precipitation and some cooling for Thursday. With a return to a westerly flow increased wind can be expected for the period.

Snowpack Summary

Continued small amounts of precip with little to no wind have added to the storm slabs over the 0314 interface now 40 to 60 cm deep. Crusts have formed on solar slopes. The 0314 interface is a rain crust that extends to around 2000m. Another rain crust below it is thinner but extends to 2300m and will likely limit activity from the Feb Facet layer.

Avalanche Summary

During this cold and calm period, Loose Dry Avalanches have been seen out of steep terrain for the last few days. Today, a small cycle of loose wet avalanches occurred with intense solar heating despite relatively cool air temperatures. Temperatures are expected to spike Tuesday with clear skies: expect an increase in avalanche activity to occur.

Confidence

Intensity of incoming weather systems is uncertain

Problems

Storm Slabs

With significant warming Tue and incoming precipitation for the rest of the week, expect these slabs to become more reactive. Small changes in aspect and elevation seem to change the nature of these slabs so monitor what you are skiing on closely.

Choose well supported terrain without convexities.Dig down to find and test weak layers before committing to a line.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Loose Wet

Heating on Tuesday will effect steep solar slopes and features such as cornices or snow near black bodies such as trees or rocks. Similarly, with some potential for rain at low elevations Wednesday, be cautious with the slab over the buried crust.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Avoid avalanche terrain during periods of rain.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 2

Deep Persistent Slabs

This weak faceted layer from early Feb may still be an issue in isolated thin and high elevation locations. With the changing weather in the next few days, snow is likely to be moving: a falling cornice or small avalanche could trigger this layer.

Minimize overhead exposure during periods of heavy loading from new snow, wind.Pay attention to overhead hazards like cornices.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

2 - 4

Valid until: Mar 27th, 2014 4:00PM