Weather delayed Alvaro Saborio's first-half pk for over an hour before the game ended two apiece.
RSL grabbed an early goal, with Ned Grabavoy the scorer in the second minute. The midfielder was poorly marked coming in from a wide position, and only had to touch home Kyle Beckerman's low cross.
Colorado didn't let the goal stand for long. Marvell Wynne put an acrobatic midfield header up the pitch, and Deshorn Brown muscled off two Real defenders to stick his foot out and poke the ball past Nick Rimando in the 9th minute.
RSL's third goal took a turn to the bizarre. Drew Moor was whistled up in the box for tripping Robbie Findley, but before Alvaro Saborio could take the penalty attempt, the officials called a weather delay due to lightning. Sixty-two minutes later, the game was back on, and Saborio converted the spot kick to take the lead.
Jaime Castrillon equalized in the 70th minute, heading in a cross from Chris Klute after the fullback had raced down to the byline.
In the three meetings between the two sides this season, there have been two draws and a Rapids win, meaning Colorado takes the Rocky Mountain Cup for the first time since 2006.