I live in West Tennessee, and when it rains here, it pours. We've been getting a lot of flooding lately, and when I drive on flooded roads (Maybe 2-4 inches of standing water) and knock up rooster tails, my power steering will stiffen up very noticeably. Within a minute or so, I'll hear a loud whine as the pump kicks it into gear and then the steering will loosen back up.
So I guess my question is, why is my power steering scared of ~3" puddles?

 

Your serp belt is getting wet and slipping.
Drive slower through the water, problem solved.

 

Inspect and or replace the serpentine and possibly the belt tensioner.

 

x2 on serp belt and tensioner, it should not be scared by 3" puddles.