What do ice pellets encountered during flight typically indicate?

Ice pellets, also known as sleet, typically indicate that a warm front is about to pass. This phenomenon occurs when a layer of warm air overlays a layer of colder air. As precipitation falls from the upper levels of the atmosphere, it begins as snow but melts into liquid raindrops as it passes through the warmer air. Then, if it encounters the colder air closer to the ground again, the liquid droplets freeze into ice pellets before reaching the surface. This transition illustrates the distinctive characteristics of a warm front, which is associated with the gradual increase in temperature and pressure changes as the front moves through. The presence of ice pellets, therefore, serves as a clear marker of this atmospheric condition related to a warm front's approach.