The West Side Highway is a pretty nutty road to begin with. You've got lots of crazies from NJ and northern NY coming south into lower Manhattan and Brooklyn, and then you've got all kinds of Brooklyn and Manhattan yahoos heading North to escape the city. Add narrow lanes, off-kilter bumps and humps, and you've got a recipe for disaster. And I didn't even mention rain yet.
Drainage is a major issue. When we get a soaking rain like we have in the last 24 hours, both outside lanes are exceedingly dicey. Puddles accumulate on either side of the three lanes in either direction creating a sort of hydro-plane suction trap. When the tires on only one side of the car meet a deep puddle, the water slows that side of the car down essentially forcing a certain yaw movement towards the outside of the lane (AKA the curb or barrier). Looks like exactly what happened to the little white car pictured above, poor guy, probably happened in a matter of 5 seconds, next thing he knew he's staring at a tree embedded in the front of his little Hyundai (Thanks for the correction sp3cializ3d).
So yeah, if you ever have to drive on the West Side Highway in the rain, stick to the middle lane. (unintentional rhyme could be used as a good Manhattan driving tip/mantra)