Bright light becomming glowing oval white light with two multi-colored lights zipping by at high rate of speed.

I still remember like it was yesterday.  It was a warm August night, (not sure though on the date, either 1993 or 94) and I was out on the front porch at home and I just happened to glance up and saw a very bright blinding light that was moving in my direction.  As I looked up it seemed to pick up speed and as the object moved overhead and to the side a bit, the light became an oval glowing white light and I noticed a smaller red glowing light on one side and a small green glowing light on the other.  The object whizzed by, arcing downward and disappearing from sight.  It made no sound at all.  It was very low, just above the tree-tops.  I saw no solid mass that the lights could have been attached to, as this sighting took place on a clear, dark, moonless night.  Total sighting lasted only about 2 seconds.  I was in absolute awe of what I had just seen.  I ran around back of the house to see if I could still see anything.  At that time I became overcome with fear.  I had read stories about men in black showing up at people's doorsteps after seeing a ufo and threatening them not to report such things.  With that in the back of my mind, I locked all the doors and told my parents about what I had just seen.  Nobody ever showed up at the door.
Although all aircraft are equipped with white lights and a green light on one wingtip and a red light on the other wingtip, this UFO's lights were too dim and too large.  They were glowing, not shining, like aircraft lights do.  And all the lights were clustered together, unlike an aircraft's.  This was completely silent, moved way too fast, and low, to be an aircraft of any kind.  It was moving North.  This also happened to be around the time that Napa was plagued by unmarked black helicopter traffic for months.
Date is approximate.  One of five interesting reports from same witness.  PD