Avalanche Forecast

Issued: Apr 3rd, 2016 9:16AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs, Cornices and Persistent Slabs.

Avalanche Canada ghelgeson, Avalanche Canada

Winter and Summer are clashing in a pretty typical Spring fashion Monday. The day starts warm and then turns stormy with a healthy amount of wind expected. Be sure your travel plans account for a wide variety of changing conditions.

Summary

Confidence

Moderate

Weather Forecast

There is a lot of uncertainty in the current weather forecast as winter and summer battle it out in this season we call spring. In short, temperatures are expected to cool a bit Monday and Tuesday and the Cariboos should see a bit of precipitation before the ridge rebounds and sends the freezing level into the heavens once again. MONDAY: Freezing level beginning near 2000 m, lowering throughout the day to around 1500 m by sunset, 4 to 8 mm of precipitation expected, overcast sky, moderate winds first out of the southwest switching to northwest in the afternoon. TUESDAY: Freezing level beginning near 1500 m rising to around 1800 m, overcast sky, convective snow/rain showers possible, light to moderate west/southwest wind. WEDNESDAY: Freezing level starting around 2000 m, rising to over 2500 m throughout the day, no significant precipitation expected, strong to extreme west wind, sky steadily clearing throughout the day. For more detailed mountain weather information visit avalanche.ca/weather

Avalanche Summary

Over the last week the very warm temperatures have initiated a lot of avalanche activity. As recently as Friday size 2.5 isothermal slab avalanches were reported from all aspects including north. Earlier in the week avalanches to size 3 were failing on the late February crust. Loose wet avalanches to size 2.5 were reported from all aspects/elevations except for high elevation north over the last few days. Cornice failure has also been rampant triggering avalanches up to size 3.

Snowpack Summary

The warm daytime temperatures and weak/non-existent overnight refreeze over the past few days have moistened the upper snowpack at all elevations. High elevation north may be the last hideout of relatively "cold" snow heading into Monday morning. Below 1400 m, the snowpack is likely fully isothermal. The March 20th rain crust is present to around 2000 m, but the warm temps have likely allowed the overlying 30 to 50 cm of snow to bond well. Once it freezes, March 20th should not be much of a concern. The late February persistent weak layer is now down 80 to 160 cm below the surface. While it may be a concern in isolated terrain, it would probably take a large trigger like a cornice fall or surface avalanche in motion to provoke it.

Problems

Storm Slabs

An icon showing Storm Slabs
Up to 10 cm of snow is expected at upper elevations Monday with strong winds first out of the southwest switching to northwest in the afternoon. The new snow should bond well to the old slop, but wind slabs could be problematic at upper elevations.
Avoid freshly wind loaded features.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

An icon showing Cornices
Monday is expected to dawn warm, and then cool throughout the day, so cornice failure remains an issue. You should feel scared if you have to travel below one of these, even if it's hundreds of feet above you.
Extra caution needed around cornices with current conditions.>Do your best to avoid traveling on or underneath cornices. If you have to, move quickly and only expose one person at a time.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Persistent Slabs

An icon showing Persistent Slabs
Cooling temperatures Monday should put the lid on the persistent slab problem for the day, but there may still may be isolated natural failures from extreme terrain.
A buried persistent weak layer (PWL) is lurking in our snowpack which means there is potential for large destructive avalanches that have the capability to run full path. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Apr 4th, 2016 2:00PM

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