Winter storms are taking a toll on the Red Cross blood supply across the country. Recent storms closed schools, disrupted travel, knocked out power for hundreds of thousands of people and had a serious impact on American Red Cross blood collections. American Red Cross Wisconsin Region spokesman Justin Kern says so far this year the Red Cross has been forced to cancel over 500 blood drives across the United States. Kern says in Wisconsin the situation has not been quite as bad. The national blood supply has been at crisis levels since early January.