Avalanche Forecast

High

Numerous large avalanches have been occurring with the recent heat. These slides are starting as slabs, and running full path to valley floor as wet slabs/loose wet avalanches. This will likely continue until such time as there is now snow left.

Valley floors are almost snow free below 1900m but above this the winter snowpack remains in many areas. The first week of May saw many large avalanches that were failing on the weak basal layers and we expect this trend to continue for the foreseeable future. Most areas now have an isothermal snowpack that is unsupportive to ground. This can all change with a good freeze though. In many areas the weak basal facets still persist under all the winters snowpack and this layer has been producing large destructive avalanches.

The heat has descended and the snowpack is rapidly melting. As we transition to spring ratings its important to consider a few things with regards to the overall danger rating.

1. Quality of overnight freeze. - With a poor freeze the avalanche danger will increase quickly as temperature rise. When in a frozen state the snowpack will be somewhat stable. Timing is key. Hence we always say, early starts and finishes.

2. Incoming snow/rain. Even though its spring, if we get a winter storm, avalanche problems such as loose wet, loose dry and even wind and storm slabs could once again be a concern. The deep persistent avalanche problem will likely be with us until all the snow is melted. With rain, the snowpack will become saturated and very weak.

3. Freezing level. The weather stations are a good way to see how cold it got overnight prior to your trip. But be sure to check valley floor and the treeline stations as there can often be an inversion in winters with warmer air above freezing at higher elevations.

4. Aspect you are travelling on. While this is more of a terrain decision, the heat will first affect solar aspects. Think about overhead terrain as well as elevation. You may be down in the shadows but higher up, it may already be in the sun.

Check the weather before you go is critical! Forecasts are now done for the season so be sure to invest lots of time into planning your trip prior.

More details can be found in the Mountain Weather Forecast.

• Remember that in the spring strong solar radiation and warm temperatures can weaken the snow in a matter of minutes.