To best support an informational report on current winter weather in the Midwest, option a: a bar chart displaying anticipated weekly snowfall amounts would be the most effective choice. This visual representation would provide clear, quantitative data regarding expected snowfall, which is directly relevant to understanding current winter weather conditions.
While the other options have their merits, a bar chart specifically addresses the report's needs by illustrating data trends and making it easy for readers to grasp the expected snowfall over the coming week.