Much of California on Monday was preparing to be hit by a powerful winter storm carrying treacherous thunderstorms, high winds and heavy snow in mountain areas. Jacob Spender, a weather service meteorologist in Sacramento, urged people to take precautions in the coming days, advising them to pack winter safety kits, especially if they plan to travel. Pacific Gas & Electric said in a news release that it was using artificial intelligence and machine-learning enhanced weather models to help determine where to send crews and equipment like power poles and transformers ahead of the storm.