ACMG Mountain Conditions Summary for the Rockies and Columbia Mountains issued May 15th, 2008.
The May long weekend is coming with blue skies and warm temperatures in the forecast. Sounds like a great weekend to be in the mountain but---
Today was the first REALLY hot day of spring. Last weeks storm snow and the whole winter snowpack are being deeply stressed by the daytime heat and solar radiation. In Canmore alone a BIG, DEEP size 3 avalanche ran today around 10:30 am in the Miners Couloir. The fracture line was around 150m wide and well over 1m deep. It ran WAY down into the snowfree ground below treeline. Several other large size 2 avalanches were visible from town. A report from Lake Louise mentioned several avalanches were triggered by explosives above the Moraine Lake road. These paths were fairly dry and they had already slid so no debris reached the road. One very large slab avalanche was observed below the East face of Mt. Babel. In the alpine and at treeline conditions are likely to get worse for awhile with a forecast of at least two more days of hot, sunny weather.
In the Columbia mountains you should assume a similar avalanche cycle is under way. The Canadian Avalanche Association and Glacier National Park each issued special avalanche advisories today. Glacier Park's report mentions a few large avalanches. Most worrisome to me was the fact that they had not had a decent overnight strengthening of the snow for several days. This is of concern for the snow stability but also for the strength of crevasse bridges.
So backcountry travel is not recommended. If you are really on the ball and IF we you get a solid overnight freeze, it may be reasonable to get up desperately early and travel safely on the snow for a few hours. If you are thinking of traveling anywhere in the big mountains this weekend be very conscious of the daytime heat. Friday and Saturday in particular have the potential for large destructive avalanches to reach the valley floor in snowy places like the Asulkan Valley and the Plain of Six Glaciers trail.
On the East Slope of the Rockies, crags are drying out very nicely and it seems a great weekend to get out rockclimbing. Many scrambling peaks are still snowy so be conscious of avalanches and rockfall in this terrain.
The good news is that this heat and avalanche cycle will definitely help destroy some of the persistent weak layers in the snowpack. We may have some fine spring skiing and alpine climbing coming eventually, but you have to survive this weekend to enjoy that.
Good Luck and please don't shoot the messenger.
Larry Stanier
Mountain Guide