This afternoon at about 5:00 pm I was sitting in my livingroom looking up at the sky for a moment. It is May 17, 2015. I was going to look away but for some reason a cloud formation caught my eye, just looked a little odd somehow. It wasn't shaped in any form recognizable like a face or anything but still held my interest. I then realized that the front of the longer thicker line of clouds was a more solid cloud and that at first thought maybe it was the stream from an airplane but the stream behind it looked way too thick for that.I watched the front of the 'cloud' with my binoculars and that confirmed that the front in fact was much denser and solid looking and in fact looked a bit like an oval but still most of it was covered in misty cloud so can't be fure of the shape.I watched the front of it as it passed from NW to almost due west when all of a sudden a jet came screaming in the same path where the 'cloud' had been and in the same direction towards it.At first I thought it was just a coincidence but when I picked up the binoculars again to look at the 'cloud' front I saw that the plane's residue line in fact was parallel with that of the 'cloud' and not far from it either. That looked too strange to be a coincidence. The positioning screamed that it was in fact chasing the 'cloud'.Then after the plane disappeared from site to the west I realized that the 'cloud' had formed the letter Z in the sky which means it went in those directions to form that letter and not only that but I was stunned when the Z plainly stayed in the same position in the sky in the west for over 3/4 of an hour. I have never seen a formation of clouds lasting more than a couple of minutes if that but this pattern was sticking. Very strange indeed.The sky is mostly blue today and the weather is still and warm. There are wispy clouds here and there but many are lower to the horizon whereas this 'cloud' formation was much much higher up which also made it stand out.Usually I don't pay much attention to clouds but have seen pictures by people who say there are UFOs in the pictures of clouds but I find most of them a stretch however this sighting was very unusual, moved unlike any flying vehicle I know of and the vapour as I said lasts much longer than the usual clouds we all have seen.At first I thought the object was the trail of a jet but the trail was way too thick for that as the front was moving in a slow but deliberate path and the front was more solid as I said.When I first saw the object I was still thinking it might be a plane trail or just an odd cloud but couldn't take my eyes off it. It was then I realized it was moving and not like a cloud but like the tail was being led by the oval solid object at th front of it - attached it seemed. There was no color I could see just cloud like. I wasn't afraid or anything but definitely amazed because as I said I have never really bought into cloud like UFOs but will pay more attention from now on.I lost sight of the object when it went around the backside of my home and I wasn't able to get out to follow it further. Actually I think it still hung in the letter Z near the bottom left side of the Z for quite a time as that spot appeared a more solid cloud like form. It was very interesting.