In meteorology, inflow bands (also known as feeder bands) are bands of low clouds moving towards a thunderstorm.
Inflow bands are often used to measure the severity of a storm, because they are what usually carry the majority of the moist air into a thunderstorm to keep it going or build it up beyond the original frontal collision. Severe ones can typically be indentified by their similarityies to a beaver's tail - flat, rounded and often patchy cumulus clouds.
An inflow band that appears to be moving in a cyclonic rotation around a storm are a good indicator of a mesocyclone, leading to the potential of tornadoes and hurriances.