Black dot moving fast on a sunny day that disappeared behind clouds on 9/29/16 at 11:45 am. Duration was 3-5 seconds.The object I observed at 11:45 am on 9/29/16 was a black dot. It was moving North to South (possiblly SE) on a sunny day with high 'puffy' clouds. I noticed it before it went behind some clouds, approxiatematly for 3-5 seconds. It was on a straight trajectory moving fast (about 2-3 times as fast as a satellite may appear at night). It left no contrail or any noticable trail of any kind. After it went behind the clouds, I could not locate it again. Idyllwild is a mile above sea level, the local peak (which was in the back ground) is about 9k feet and I would approximate the height of the UFO was 12-13 thousand feet. I am 44 years old and grew up here in Ca. I grew up between many airports and have seen airplanes (and military planes) in the sky all my life, this was not an airplane. The trajectory of this object was not of any flight path that I have seen living here over the past eight years. This is the first time I have ever seen a UFO.