No way to know that going into the open my rule of thumb is if it dont gap more than 10% at the open I usually will take a position and then let level 2 tell me what we are looking at . I am watching for it to keep a tight spread and walk it up slowly like we saw today , also want to see even flow of both buys and sells , if I start seeing a shiz ton of lop sided bid wacks thats usually not a good sign