Avalanche Forecast

Issued: Apr 7th, 2014 4:00PM

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

tim haggarty, Parks Canada

Waterton Lakes.

Even short periods of solar heating or rain may cause an increase in the hazard beyond the posted Danger Ratings. Be conservative Tuesday as the snowpack will be stressed by the highest freezing level encountered yet this season.

Summary

Weather Forecast

Freezing level rose to 2800m Monday. With a poor overnight recovery forecast, and more solar heating into Tuesday, the snowpack will be weakened further. Overnight rain with snow above 1800m and strong winds will add heat at low elevations and windloading above for Wed when more sun is expected. A better recovery is seen Wed Pm with more sun Thurs.

Snowpack Summary

Surface crusts on East through West aspects have formed with the daily heating pattern and rain below 1700m. Down 30 to 40cm on shaded aspects a shear persists on the 0325 interface. The strong March crusts are found down 70 to 100cm on all but North aspects above treeline and overlie the Feb facets that remain weak at about 1m above the ground.

Avalanche Summary

Widespread superficial loose moist activity has been seen over the last few days as a result of heating. On Sunday heating was strong enough that one of these triggered a 40 cm deep slab on an E aspect. Expect this activity to increase Tuesday. On shaded aspects and at higher elevations a few windslabs have been seen following modest new snow input

Confidence

Timing or intensity of solar radiation is uncertain

Problems

Loose Wet

Daily heating and the sun will create moist snow at low elevations and on solar aspects. As crusts break down Loose Moist or even Wet Slab avalanches will result. Cornices will also be affected by this heating and could trigger persistent slabs.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Travel early before the heat of the day, and avoid big slopes in the afternoon.

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Wind Slabs

Skiers looking for dry snow on the shaded aspects should frequently test the surface layers. A shear persists down about 30 cm with preserved stellars and surface hoar. Recent winds and new snow have contributed to the growth of these slabs.

Be alert to conditions that change with elevation.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

With significant heating in the forecast for Tuesday deep slabs may become active. Large loads such as falling cornices or smaller avalanches could trigger large avalanches on the March crusts or even the February facets.

Pay attention to overhead hazards like cornices.Be increasingly cautious on sun exposed slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Apr 10th, 2014 4:00PM