I have an issue with my garage door. The garage door passes this exterior concrete slab and extends below 3 inches. When it rains hard, water comes in under the door every time.
Currently the higher concrete slab is level, so it takes a heavier rain to make it under the garage.

I would prefer to not put a channel drain in yet if I don’t have to. I can cut the exterior concrete and report it with a slope so that it would drain away. If I do that, how far should I cut and repour from the door.?

Any other suggestions?