On my 5th wheel during a rain storm I noticed water running down the inside wall from the bottom of the window. It turned out that the caulking at the top of the window frame on the outside had dried out and was cracked. The rain water was following the window frame down and spilling out at the bottom of the window frame inside the trailer. I caulked all of the windows and haven't had a problem since.
By the way there was water in the channel where the window slides and it wasn't going out the weep holes. I guess the weep holes are only for water in the outside channel.
