Solution:

Code
set(PEEK);
		
		var up_potential, down_potential = price();
		
		for(i= -20; i<=0; i++)
		{
			up_potential = max(up_potential, priceHigh(i));
			down_potential = min(down_potential, priceLow(i));
		}
   
//until here, up_potential / down_potential is ony the highest / lowest price during that upcoming period of 20 bars.

		up_potential = abs(up_potential - priceOpen())/ATR(30);
		down_potential = abs(down_potential - priceOpen())/ATR(30);


up_potential: how many ATRs the price will move up during the next 20 Bars.
up_potential: how many ATRs the price will move down during the next 20 Bars.