ACMG Mountain Conditions Summary for the Rockies and Columbia Mountains issued May 1st, 2009.
This is the first ACMG Mountain Conditions Summary for 2009. The Canadian Avalanche Centre and Glacier National Park published their last regular avalanche bulletin for the season last week. Banff, Kootenay and Yoho are still publishing bulletins. They all deserve a pat on the back for doing a fine job over a long, often scary winter. Our goal is to maintain weekly summaries until the Canadian Avalanche Centre starts producing regular bulletins again in the fall.
The deep instabilities that caused so many avalanche involvements and fatalities this winter have ALMOST disappeared. There will, however, continue to be occasional large, nasty avalanches stepping down to those layers or to the ground when warm temperatures finally roll into the mountains or when slopes are subjected to large triggers such as cornice falls, snowmobiles or big hucks.
Spring has arrived but it has recently had a cold, cold heart. In the Rockies, the warm temperatures and sunny skies of mid April warmed and settled the snowpack dramatically. Recent temperatures as low as -18c and brisk winds in the Rockies alpine have left the snowpack with a seriously hard surface. Some new snow fell east of the Divide earlier this week and shallow wintry windslabs were/are a potential problem in the east slope Alpine and even around Lake Louise. Around the Wapta, Columbia Icefields and areas west it has been cold, dry and windy and holding an edge was often the main issue. There was occasionally some corn snow on steep south facing slopes in the afternoon below treeline but the rest of the world was rockhard. Travel was fast but ski and boot crampons felt pretty good on even quite moderate terrain and going for an ugly slide was a serious possibility.
There have been very limited reports from the Columbia Mountains. Generally, it sounds like it has been unseasonably cool and there has been variable amounts of recent storm snow throughout the Columbias falling on a spring snowpack. Avalanche hazard has predominately been the result of the wind effect on these sporadic snowfalls and most importantly, the amount of daytime warming. Again, LARGE avalanches are still a distinct possibility in the Columbia mountains, especially if we get a dramatic, rapid warming in the next couple of weeks.
Glacier travel conditions are generally good and even excellent at the right time and place throughout the Rockies and Columbias. The shallow early season snowpack and some big early season winds have however, left some areas with shallow snowbridges. Warm temperatures are going to weaken the snowpack(especially the thin areas) and make the crevasse bridges a real problem. I seem to have been touring on the glaciers with my probe out a lot this spring as I have less faith than usual in my visual observations of the glacier snowcover.
Snow fell overnight in some locations on the East slope of the Rockies. Yamnuska had a serious frosting this morning and at noon it was still white. Also at noon I saw a big wet slough pour off the cliffs to the climbers right of Goat Buttress and a BIG wet slough pouring down the gullies right of Guide's Route on the East End of Mt. Rundle. Hard to believe it will all be gone by saturday as it is only 12 Celsius in Canmore at noon friday. Could be a poor weekend for those cliffs, the Ghost River area and for Front Ranges scrambling.
It could be an excellent weekend for low elevation cragging, corn snow skiing, icefields mountaineering and maybe even some well timed, fast moving alpine climbing. Get out there and enjoy it but keep an alert eye out for a rapid or prolonged warming and it's effect on the snowpack, cornices, crevasse bridges and rock.
Larry Stanier
ACMG/IFMGA Mountain Guide