How do you get snow and hail at the same time?

Remember that hail is different than sleet (ice pellets). You only get hail from a thunderstorm with the right amount of convection. Growing up in Iowa, I do remember getting the right combination of instability in the atmosphere that we got a thunderstorm with heavy snow since it was in the upper 20's. Different areas of the cloud contained different forms of precipitation. We did experience small hail during this storm while it was snowing. Unusual, but it can happen. I also remember a thunderstorm with heavy sleet and hail. Temperature was in the upper teens. Very shallow layer of cold air over Des Moines, but warm air aloft.