We believe this is the last of a fading circumhorizontal arc. The time was about 2:37 pm PST, temperature about -2C with scattered cloud cover, the sun has just slid behind a fairly large cloud. We looked up and saw this intense spot of colour. At first we saw all the colours in the rainbow, however it faded fast and dissapeared in only seconds.

To read more information on circumhorizontal arcs click: HERE