Often when you look at radar images of hurricanes, you see powerful thunderstorms along the front, or leading edge of the hurricane. This is the rain band.
A storm moving through the atmosphere can move as a whole at speeds of 15-30 mph. This is in addition to the winds within the storm spinning at speeds of 100 mph or much higher. That storm front moving steadily through the atmosphere can push and compress air before it, just like a snowplow moving through snow causes the snow to bunch up and pile up before it.
This bunching and piling of the air gathers together any humid air and can cause it to mass into thunderstorms. This pile-up of wet, rainy air is called a rain band.
How to Prepare for a Hurricane
Naming a Hurricane
Learn More about Hurricanes
Categories of Hurricanes