Another powerful storm is expected to barrel into California later this week, but once again, San Diego should be on the southern fringe and get very little rain. In the meantime, mild weather is forecast for the workweek in San Diego County, with minor fluctuations in temperature and the reach of the low clouds. Up north, it’s a different story. An extremely wet storm, with seven times the amount of moisture usually seen this time of year, is expected to pound the Bay Area Thursday through Saturday with a couple inches of rain. National Weather Service forecaster Joe Dandrea said the Sierra could get 4 to 6 inches — a welcome, late-season addition to the state’s water supply after a subpar winter.