Method 2: WS-2902A - How to Send Weather Data to CWOP
(See follow-up post for variation of this method that we'll call Method 2.5)
There is actually another method for the WS-2902A to publish to CWOP but it is more complicated. But it is potentially cheaper than getting the ObserverIP, WS-1000-BTH (or WH32B) and Meteobridge (WeatherBridge). It really depends on what computer and network equipment you may already have.
This other method to publish to CWOP mostly requires the use of a computer (an old one you already have lying around, or a cheap one, or it is popular to use a Raspberry Pi because they are cheap, small and take up little space.) Then add some software. You'll also need an old router that can run custom firmware or get a cheap router capable of running WRT or Tomato.
The software you need for the computer is WeeWx. You'll need to use the WeeWx interceptor driver to capture data being sent by the WS-2902A display console via the custom router as it sends to Weather Underground. Once WeeWx has this data it can then publish to a number of services including CWOP. And WeeWx will then also pass along the intercepted data to Weather Underground.
In concept the above paragraph explains how it works without getting too technical. But in reality to accomplish all of that it is complex. Because it requires a whole lot more technical experience. You'll need Linux experience, router configuration experience, and networking experience to redirect Weather Underground traffic to the WeeWx computer. Keep in mind that this custom router does not replace your existing router. It sits between your display console and the WeeWx computer from a network design perspective. But there are a lot of guides and write ups. But you probably won't find all the information in one place. And if you are a real network guru and you already have a managed layer 3 switch on your network then you won't need the router with custom firmware as you'll program your layer 3 switch to do the redirection to the WeeWx computer, but your network will have to also have a wireless access point that is not the router if you are using the WS-2902A display console.
It is much easier and convenient to use the first method in my prior post, although probably more expensive.
Note: I don't have any proof but conceptually this method of capturing Weather Underground data via network redirection could potentially be a solution to get any weather station from any manufacture that publishes to Weather Underground to be able to also send data to CWOP. With one caveat...Stations like Netatmo that don't directly publish to Weather Underground via your network have no WU data to intercept. These station publish to only to their private Internet cloud service and then from there it goes to Weather Underground, so it isn't done over your network.