The diagnosis is the serpentine drive belt hydroplanes from driving in heavy rain. The rubber ribbing will sometimes burn off during the process causing the high pitched loud noise.

My '03 XC70 was sadly towed to a dealership 200 miles from home and awaits their diagnosis on Monday. We were driving in very heavy rain on a highway (50-60mph) and the front end started a high pitched noise that got very loud and sounded like it was coming from both front wheels. There was no loss...