Our species ability to control avalanches remains more art than science, which makes sense given the challenges involved. A thousand different variables play into each situation, ranging from the constitution of the snow to incremental changes in air temperature. On top of that, the means by which we knock away threatening snow—namely, by pelting it with explosives—tends to be a bit unpredictable; a mortar shell, after all, is about the furthest thing away from a scalpel, in terms of exactitude.
Yet we have made great strides in increasing the precision of the ordnance used in avalanche control, as evidenced in this awesome presentation (PDF) from the Wyoming Department of Transportation. Note the evolution in the means by which explosives are delivered to the desired impact points—we’ve gone from vintage howitzers to GazEx pipes to chairlift-like contraptions (above) that can seed a whole mountainside with bombs. The last of these innovations is important because the latest research shows that different parts of the target area should be treated with different amounts of explosives, since snow pack can vary greatly within small areas.
The lift is also important because it takes humans out of the equation. That was a major drawback with the old howitzer method.