Going to - prediction
We often use going to to make a prediction about the future. Our prediction is based on present evidence. We are saying what we think will happen. Here are some examples:
1. The sky is very black. It's going to snow.
2. It's 8.30! You're going to miss the train!
3. I crashed the company car. My boss isn't going to be very happy!
In these examples, the present situation (black sky, the time, damaged car) gives us a good idea of what is going to happen.