Light reflected off of a flat surface like water is horizontally polarized. Vertically polarized sunglasses will block this horizontally polarized light. Thus polarized sunglasses are highly effective for boating, fishing, and driving on wet roads. I highly recommend polarized sunglasses for driving up to the ski area.
Snow is not a flat surface. The ice crystals are oriented in many different directions, thus the light reflected off of snow becomes polarized in many different directions. Thus polarized sunglasses do not really help on snow. Unless you're skiing on a wet sheet of ice. I myself will just go to the bar in those conditions.
This is mostly true! Although the glare and reflections are not as uniform as on a simple flat surface, a polarized lens will still make a difference. As you're saying, though, in those icy conditions, the polarized lenses cut even more glare because it is flatter. We also recommend a polar for the drive up! Glare can be a big distraction while you are driving, so cutting it helps.
Snow is not a flat surface. The ice crystals are oriented in many different directions, thus the light reflected off of snow becomes polarized in many different directions. Thus polarized sunglasses do not really help on snow. Unless you're skiing on a wet sheet of ice. I myself will just go to the bar in those conditions.