From a fixed point, the object zigzad north and south, covering a 16 miles distance in no more than a second or two.

I observed a round shinny ball, the size of Venius, moving on a 090 degree heading at 13,000'. At first, I thought this was a departing jet, (with landing lgts on, from Portland International airport (PDX). However, there was only one round light, and that light came to a stop directly over Mt. Hood. The object's light grew in intensity, then the light abruply zigzad north and south at about a 8 mile direction (each way)in a split second, coming to an abrupt halt each time. The light came back to it's original course and proceded to move slow at first, then speed off, and out of site, within a two second period.
Later, I asked the park ranger if they ever get UFO sightings, and he said, "all the time!" This is the first time I made any UFO report.