One small change in the world has led to mind-blowing effects for Northern California, nature and the outdoor prospects for winter and the next year. That small change was a shift in mid-October in the location of the jet stream, the conveyor belt of storms. The deluges that have followed stopped a Tahoe fire, saturated soils, put many reservoirs at 100 percent of average for the date, fed wetlands in time for arriving waterfowl and shorebirds, and put ski parks in line for a chance at a big season. One of the best indicator sites is the weather station at the Blue Canyon airport, at 5,284 feet near Nyack along Interstate 80.