Terra -- not sure if someone else has answered your question, but the short answer is no, they don't all follow the same pathway.

For instance, here at FSU until this year, there was two options: the applied option or the graduate prep option. The applied option meant you could get out of 2nd level Atmospheric Physics & Dynamics courses while taking a bunch of technical electives; the graduate prep option was straight-up meteorology designed for academic/research progress. Most weathercasters took the applied option. Some other schools have similar programs, while others have schools/programs devoted exclusively to broadcast meteorology.

Some people on the Weather Channel and a few across the nation (usually weekend meteorologists in small markets) have no weather background whatsoever and are just personalities. Alexandra Steele has no background in meteorology, for instance, and I know of a couple of people in NC that have been doing weather on TV for years but never had any training.