Weighted random with two weights

In PHP I need to pick a random number between 1 and 100 with two weights. These weights can also be between 1 and 100. If both weights are low I would need the random number weighted low, high weighted high. If one weight is high and one is low, or if they are both mid ranged, I would expect random number to be weighted random around the 50s.

I'm not sure the best way to go about this. Any advice would be great!