I live in Denver. Last night we had a lot of rain. I went to open my basement window and I caught some movement out of the corner of my eye. I have this lizard/salamander looking thing in my window well. It’s about 7 or 8 inches long (about 1/2 that is tail). It is bright yellow and black stripes. The stripes go around it’s body, not up and down.
I’ve found tiger salamanders wandering around parking lots north of Denver, so they are around and fairly mobile. They weren’t as vividly colored as those in CannyDan’s link, but tiger salamander would be my first guess.