Ice pellets encountered during flight are normally evidence that:

Ice pellets, also known as sleet, form when there is a specific atmospheric profile present. They are typically produced when raindrops fall from warmer air above and then pass through a layer of subfreezing air near the surface. This causes the liquid droplets to freeze before they reach the ground. When ice pellets are encountered during flight, they indicate that there is freezing rain existing at higher altitudes, as the initial rain forms and then refreezes in the colder air below.

In the context of weather patterns, if ice pellets are present, it often signifies that a layer of warm air exists aloft, leading to freezing precipitation occurring as those droplets descend through colder air at lower altitudes. This process directly relates to the presence of freezing rain in the surrounding atmosphere.