By TIM TALLEY Associated Press OKLAHOMA CITY – A winter storm that brought heavy snow and rainfall to northern California was bearing down on the southern Plains on Thursday, and forecasters said crippling ice accumulations and heavy rain could cause widespread power outages and flooding this weekend. The National Weather Service issued an ice storm warning for northwestern Oklahoma beginning Friday morning as well as a winter storm watch for much of the rest of Oklahoma, Kansas and Missouri along with parts of Illinois and Texas.