Here is a thought. When the sun comes out, it melts snow. Melted snow is water. Thin layers of snow will melt faster than a thick layer of snow. The ground snow is thicker than snow found elsewhere. Can this give a us clue?
When the sun came out, there could be snow or ice in the branches of the trees. This would melt faster than the snow on the ground. When it melts, it will turn to water. The dripping water would form a drip line that is no bigger than the tree in diameter. As the water drips it lands on the snow. Since the temps are now above freezing the water will melt the snow on the ground within the drip line.
Also, the trees shade much of the ground snow, but high in the tree the sun is directly hitting the snow and ice on the branches. Multiply the height of the tree times the amount of water being formed on just one branch. Could be quite a lot of water dripping into the drip area under the tree.
A Spiritual thought: Even those in darkness will benefit from from those who receive the light.