Purcells

Tuesday will be a warm and windy day in the mountains. The high freezing level in combination with extreme ridge top winds may be enough to initiate a cycle of large destructive avalanches. Stay conservative in your terrain selection Tuesday.

Fair - Freezing levels are uncertain on Tuesday

The provincial weather pattern is dominated by an intense pacific front that impacts the coast Monday afternoon, continuing through Monday night. Remnants of the once great system stumble into the interior Tuesday. Tuesday: Advancing front pushes the freezing level up to 1900m while amplifying ridge top winds up to an extreme 90 km/h out of the SW. 2 -5 cm of snow expected in the afternoon. Wednesday: Things calm down behind the frontal passage. The freezing level should be at the surface by Wednesday morning with very light northerly winds at all elevations. 4 - 8 cm expected Wednesday afternoon. Thursday: No precip forecasted, the freezing level should top out around 1400m. High and dry conditions for the foreseeable future should make for excellent ski traversing weather.

A few more details have come in from the skier triggered avalanche west of Invermere Sunday; The avalanche was reported to be size 3 with a crown that measured up to 200cm at the thickest points. The avalanche failed on the October crust interface and was likely driven by a rapid increase in temperature. Elsewhere in the region avalanches went as big as size 3.5 over the weekend.

The most recent storm produced 20 - 100 cm of total snowfall. The storm snow rests on a layer that is proving to be quite volatile; the March 27th crust/facet combo. This layer, consisting of a melt freeze crust & small grain facets has been quite active over the last 72 hours across the province. Avalanches have been remote triggered on this layer from hundreds of meters away. At lower elevations below treeline the crust was moist at burial which resulted in a more substantial bond.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 recently. 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 refreeze (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 enter early 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. 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 cornices are warming to their breaking point, then, there's no question, it's time to get off that slope.2. 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.