We got to Typhoon Lagoon at around 5:20 PM, it had clearly rained in that area of WDW even though it hadn't rained on us to that point. As we were walking into the park we had a loud burst of thunder and lightning and the park's activities were shut down until about 6:05 after the dark clouds had rolled past.
For the last two hours that park was a great place to be; very small crowd, the wave pool had plenty of room to swim around in and body surf. My son and the other smaller kids got the chance to run and swim out into the pool when it was reopened like they were skiing on virgin snow. None of the slides had any wait worth mentioning, basically you had to climb up to the top and then wait for one or two people to slide before you.
While we didn't have a long day at the water park we clearly had two very good hours. When we were pulling into the lot (before the closing occured) the traffic was only heading out and were were able to park in the first row for cars.
Thanks for the help.