Hi Dale, and welcome to the WeatherCat forum!
WeatherCat is the continuation of LWC, and can inject your existing data without a hitch. It fixes any niggling problems that LWC had, especially those related to using Mac OS X 10.7 Lion, and adds new features and tags. Think of it simply as LWC 3 with a different name.
Give it a try, as the current beta is very stable and just a week or two from release.