Avalanche Forecast

Fair - Intensity of incoming weather is uncertain on Tuesday

An active weather pattern is in place for the next 72 hours. Sunday: An upper trough crosses over the region bringing of 6 -10 cm in the morning. A ridge builds in the afternoon generating clearing skies & ridgetop winds out of the W at 20k. Freezing level tops out around 1500m in the afternoon. Monday: The ridge continues to build ahead of a well-organized system that impacts the coast. Strong winds, even below treeline out of the SW amplify in the afternoon. Freezing level tops out around 1500m. Snow starts up after sunset, 5 - 10 cm are expected overnight Monday. Tuesday: 10 - 20 cm expected Tuesday with Strong winds out of the SW. Freezing levels start the day near 1100m, climb to 1600 during the afternoon & should return to the surface Tuesday evening after frontal passage.

A widespread avalanche cycle occurred Friday in the Purcells with avalanches triggered naturally, by skiers and with explosive assistance. Avalanches averaged size 2, failing within the storm snow, there was one natural size 3 as well. Activity slowed on Saturday; all reported avalanches were explosive triggered.

15 - 80 cm of snow fell from the storm over the last 72 hours as of Saturday afternoon. In wind exposed locations this new snow has been formed into wind slabs which could be up to a meter in depth in the north of the region. In the south these slabs are closer to 20 cm in depth. Spring the season has arrived, and it's not just calendar spring either, it's really felt different in the mountains recently. The snowpack is far from isothermic, but the mercury has climbed above 0 as high as 2500m over the last 7 days. These warm temps have really helped to settle out what now is the mid pack. Slopes below 1000 m continue to experience little or no overnight recovery. The spring sun is increasing in strength as each day grows by a few minutes. It takes very little time for S, SE & SW aspects to feel the heat of the sun now, observers report that SW, S & SE slopes are being cooked almost instantly when the sun pokes out. W & E facing slopes are jumping in the mix now too & will be affected by the sun as we start the month of April. As soon as the sun comes out, watch for roller-balling & pin-wheeling to start surprisingly quickly. Wet point release avalanches won't be far behind on slopes receiving direct sun.There's a lot of strong snow between recreationists and the February surface hoar layers and there hasn't been a deep slab avalanche in the region since Saturday March 24th. Deep slab avalanches may still be possible. I'm thinking of two different scenarios at the moment:1. The most likely scenario is a large cornice or icefall failure impacting the slope below and producing a very large avalanche. Managing this piece of the hazard puzzle is done by monitoring what's happening above you. Cornices or slopes receiving direct sun are suspect. If you feel like there's a question as to whether or not a piece of cornice is warming to its breaking point, then, there's no question, it's time to get off that slope. 2. Last weekend an experienced party remote triggered a very large avalanche in Glacier Park near Mt. Tupper. At this point I think the probability of human triggering the deep slab is very low. I don't really want to be proved wrong though, as the result would be large and destructive avalanche 1.5 - 2 m in depth. The most likely location for this type of failure is where the snowpack goes from thick to thin. This is most likely near ridge crests, the edges of slopes and especially around rock outcroppings.