The flagship winter tire for Bridgestone is their Blizzak WS70. It is an unbelievable tire in providing grip in both deep snow and icy conditions.
The tube multicell compound allows this tire to temporarily absorb microscopic amounts of water that keep normal tires from making good contact with the road's surface. This gives you, the driver, better grip.
Improving upon the Blizzak WS60, the WS70 has more tread depth for better bite in deep snow conditions. After having tested this tires versus its main competition (Continental ExtremeWinterContact and Michelin X-Ice Xi2) I wouldn't trade the Blizzak WS70 for either.