They do well in rain but snow remains a problem, not due to icy roads (at SXSW Chris Urmson said they do well on slick roads) but that the "better than GPS" LID

They do well in rain but snow remains a problem, not due to icy roads (at SXSW Chris Urmson said they do well on slick roads) but that the "better than GPS" LIDAR-based location tracking stops working when snow is on the ground. The car simply cannot figure out where it is when there's a significant layer of snow on the ground because the reference maps stop looking like what the car is seeing. https://youtu.be/Uj-rK8V-rik?t=46m22s https://youtu.be/Uj-rK8V-rik?t=46m22s