Final answer:
An almanac would be the most effective source for finding information regarding predicted weather forecasts for the entire year, as it contains annual weather predictions and other relevant details. Other options like regional maps, encyclopedias, and previous weather reports are not specifically designed for long-term forecasting.
Step-by-step explanation:
In determining which source would be most effective for finding information regarding predicted weather forecasts for the entire year, an almanac would be the best option. An almanac contains weather predictions, often covering an entire year, and provides other details such as astronomical data, which can be useful for planning agricultural activities, among others. While regional maps and encyclopedias might provide some general information, they are not specifically designed for long-term weather forecasting. Weather pattern reports from the previous year can offer historical data, but they are not predictions and thus may not accurately reflect the current year's weather. Modern sources such as the National Oceanic and Atmospheric Administration's online forecasts or the Weather Channel are also valuable resources providing up-to-date and detailed weather forecasts.