A lot of times, it really depends on the weather. If it's warm enough, people will come in droves to go to the waterpark. It affects people that just go to the regular park too because some people go to the waterpark for only a few hours, and come out of it. It also depends on the weather depending on rain or not. Than, you have to look at whether or not Six Flags has something in the coupon book for bring a friend for free, or half price, or whatever else. Also, just because it's 70s, doesn't mean that no one will come to the park at all. Very little people will be in the waterpark in the low 70s, but the regular park will still have some people.
The buses usually come to the park even if the weather is not the greatest, and Six Flags has been selling to a lot of groups / buses this year it seems. There are other variables such as whether or not coasters in particular are not open. For instance, if Superman & Whizzer have mechanical difficulties for the day which could be possible, than that is going to make so many other coasters more packed. More than at least a 1000 people per hour (if those 2 broke for the day) would have to go to another line.
Back to weather, drizzle can shut down Whizzer & Ragin Cajun. If the weather is bad for a day or 2 -3 days in a row, people might decide to go to the park on a non cold or rainy day instead, and make the park more packed on a particular day because it's not bad. For example, let's say SFGAm gets 2 days of bad weather with 7,000 people each day. On the 3rd day (Let's say the 3rd is a Thursday), for that day, they might get 20,000 people because the other days were terrible. This scenario is especially prevalent for this year because we have had a lot of bad / rainy days already.
Another variable could be for this week, is that how many people can't wait to see the Ignight show. This really is the first week of Ignight.
In my opinion though for this week on Wednesday, the biggest problem for you that could bring in crowds is the bring a friend for $10 thing! The weather doesn't seem great as in hot enough for many people to go into the waterpark. Ignight is new, but I don't see much advertising about Ignight. I see more about Batman backwards instead.
"I've been staring at the world, waiting. All the trouble and all the pain we're facing. Too much light to be livin' in the dark. Why waste time? We only got one life. Together we can be the CHANGE. So go and let your heart burn bright"