Issues with your counter flashing are normally the number one reason why a bay window can leak.
Bay window roof flashing.
Often due to the age of the house the original roofing sealant will break down and start to crack and fall apart.
Flashing bay windows featuring master mason bryan light the brick masonry techniques for builders dvd demonstrates construction techniques with brick that.
We always apply i w before all flashing details as a temporary dry in procedure and second layer of defense against leaks.
Install your drip flashing around the eaves of the bay window roof.
We would have used a longer step flashing along the angled walls of the bay porch roof intersection.
Nail it in place.