You would definitely need to be going at a very good clip (as I said), again depending on the width, but just pointing out that it is possible.

And it has more to do with the overall width than the tread pattern. Yes, the tread pattern has an influence on how much water can be channeled away from the contact patch, but it's more to do with pressure and surface area. The wider the tire, the easier it is to hydroplane. As mentioned in another thread, this is why rally racers use very skinny tires in the snow. It's the same principle.