Triangle craft seen in Westminster Colorado.Triangle shape. Could not make out color. Low cloud cover that morning. The craft was flying just inside the cloud. enough to make out faint outline and lights. There was a light on the bottom in each of the three corners. There were also lights at about the midpoint of each side. Those lights were at the upper and bottom part of the sides. These lights seem to blink or pulse in a certain pattern while changing colors. The craft was moving approx. 400 miles/hr, and there was no sound. The craft flew about 1/8 to 1/4 of a mile to the west of my position, using the clouds for cover. I would estimate the craft was about 200 to 300 ft above ground. I watched it until it vanished into the clouds about .5 to 1 mile north of my position. I noticed the craft when looking at the mountains out of my work window. I thought it might be a reflection of a passing car or a plane landing at the jeffco airport. I went outside to rule out reflection, and it was still there. I ruled out plane when I noticed that it made no sound and was traveling parrelel to the airport runway's. I also ruled out plane by the way the lights were flashing.My Background, 27yrs old, Engineering Drafter, I believe in ufo's and e.t. Never seen a ufo and skepticle when I listen to stories. Never met e.t. as-well. Associates degree in drafting.