The snow that

The snow that softened on the upper top zone will solidify as it moves onto the lower top region if that lower territory is colder than at the top, which typically is the situation. Commonly, the lower range of the top will remain colder than the upper top territory, particularly in the region just over the eave, where temperatures may not be much higher than the surrounding outside air. In the event that the open air temperature is well underneath solidifying, conditions for ice dam shaping are positive.