Your might be different, but our 2013 Adventurer has a series of slots along the bottom of both the drivers and the passengers side windows. The slots are supposed to have weep hole covers over them with the rear side open. Their purpose is to eliminate wind noise that would be generated if the slots were left open.
Several of ours were either broken or missing allowing the wind to generate noise. I was able to move around the remaining ones to eliminate the noise. When we take the coach in for some service work later this fall I'll have them replace the missing ones.