After a chilly week and a Friday of drizzles, the Bay Area can expect a prolonged shift to drier, warmer weather. The San Francisco office of the National Weather Service is forecasting that rain will spread from the North Bay late Thursday to the rest of the Bay Area on Friday before tapering off at night. It shouldn’t get too intense: The weather service isn’t predicting more than an inch of rainfall anywhere, and less than a half inch everywhere south of Santa Rosa.