With the heat came wet avalanches, so awareness of the terrain and changing snowpack conditions was important. I even watched a few slides trigger naturally from close by.
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Average annual precipitation here is around 300cm, most of which falls during the wet season as snow from October through April. Average annual snowfall at the ski resort is 16.3 meters, and the resort also holds the official world record for most measured snowfall in a season (1998-99) with 29.0 meters. Precipitation is even greater closer to the volcano, but it has never been measured.
Not unless YOU were part of the renovation crew that left a burning cigarette somewhere in Notre Dame! At least that is the latest cause I've heard. Another is that a glitch in the security system caused it.