97 Jetta GLS
So this is a new thing - I take my car through the car wash and about half way through the wash I start noticing that water is coming in from under/behind the glove box. And its not just a little but enough to fill my passenger side floor. Is there anything I can do to prevent this?

You can remove plastic the air plenum cover on the right side of the car under the hood by the wipers. You only need to remove the three of four plastic screws & the rubber strip so the panel will come out. You probably have alot of debris clogging the drain under there.

..do you have a sunroof? If so check the drains in there as well..pour water from a gallon jug slowly in the area around the seal. If you see water in coming into the car you'll have to have the lines replaced.