For my 2002 Ford Focus SE, over the past weeks a noise started that is
coming from around my front passenger side wheel.

The odd part is that it only happens in specific situations and at
specific times of the day: absolutely bizarre.

What happens is that if I park my car in my work parking lot on a very
slight grade, and then leave work late at night when it is cooler
outside, when I back my car out of the parking space I hear a rubbing
noise from around my front passenger side wheel. When I then pull out
of the parking lot, when I hit any slight dips in the road, I will
hear the rubbing noise. just during the dip.  When I take the first
interstate ramp to get on the highway, I will hear noise from the
wheel area when I go around the sharp ramp to get onto the
interstate.  However, from that point forward, and at all other times
of the day, the noise goes away.  At the same time of the day I can
drive from other locations and not hear the noise.

I jacked up my car and pulled on the tire, and the bearing does not
appear to be loose.

Does anyone have any idea what it could be?   Or, any other tests I
can try to diagnose the problem.