We are doing final planning for our Cali Road Trip. When I look at a map of Cali, there are certain roads that are labeled as 'closed in winter'. 120 in Yosemite, and 180 and 190 in Giant Sequoia for example. How do we know if these roads are open for planning the trip? Do they open them on a certain day? Should we just assume that they are open by the first week of May?