Both are statistical in nature and have computer models that assist in prediction but rely heavily on sampling in the area to determine with any certainty what is actually going on. Someone else might be using the frequency you've picked and they didn't show up on any of the lists you have. The only way to be aware of these and many other problems is by monitoring . To forecast weather just for the United States, there exist thousands of sampling points, thousands of direct and contract employees to maintain and analyze data, and tens of millions of dollars spent annually in hardware and software support. Not much of a comparison.
Monitoring is all about data collection and management.
Our philosophy is to get as much high-quality data as possible into the hands of our schedulers as quickly as possible in a format that allows them to make meaningful improvements in reception quality.