Squealing Noise

I have a 2004 Trailblazer which makes an intermittent squealing noise at speeds over 60 MPH. The noise is high pitched, and very aggravating.
The dealer can’t seem to locate the problem because when they take it for a drive, it won’t squeal! (Figures, right?!)
The noise sounds similar to what you hear from the warning tabs when it’s time to replace the brake pads.
It is not the warning tabs, nor is it the brakes. Both have been checked.
Tapping or slamming on the brakes makes no difference in the squeal.
Activating the emergency brake also has no affect at stopping the squeal when it is occurring. .
Here are some additional symptoms:
* Squeals more during dry weather, or after the vehicle is parked facing uphill for a long period of time
* The squeal is of a slow variety, not rapid like you would hear on a rotating tire
* Squeal is triggered more often when I am in a right-hand bend on the freeway or I hit a bump… Again at speeds over 60 MPH
* The noise temporarily disappears when I step on the gas (take weight off the front end) or when I slow down to below 45 MPH.

Any suggestions on what to look for would be greatly appreciated!!

Squeals are usually brakes or fan belts...Have them replace the fan belt...