As our planet warms the winter snowline creeps higher up the mountain slopes. It does so in fits and starts. There are still “normal” winters, but when we get a warm winter combined with below normal snowfall, the February snowline can resemble that of April. As pilots we are interested in how a high snowline in the winter translates to springtime flying conditions.
The ‘energy budget’
Two important metrics for determining the type of mountain flying we might expect in any season are the convective boundary layer depth and the strength of the valley wind. Thermal strength is a combination of convective boundary layer depth and positive sensible heat flux (the transfer of heat energy between the Earth’s surface and the atmosphere via conduction and convection.)
Before considering the role of snow and the winter snowline, it is worth reviewing the concept of an energy budget. In...
