round object moving in and out of thundercloud, after flitting back and forth,sped north at high speedas we were driving south on I-35 towards walsenburg,co, i noticed a round black object that was going back and forth into a tall thunderhead that was forming SE of our car. I watched the object for approx 2 minutes,at that time the driver of the car asked what i was staring at, when i told her she requested that i steer the car while she attempted to spot the object. at the time the thunderhead was building about 20 miles to the SE. she spotted the object(i could not see as i was steering car)she watched it dive towards the ground ,level off, then shoot at high speed toward the north. she described object the same as me, a dark round object, no lights, size hard to estimate due to nothing around for reference. this was a daylight observation,in good conditions,excellent lighting...