I would check the screen saver setting to make sure it didn't reset to default (which I believe is no screen saver). I have mine set to the clock so not sure if Weather Channel works or not.
The configuration is under Settings --> (enter your passcode) --> Touch Screen --> Screen Saver Configuration.
Here you should have the option to set the app you want to launch for the Screen Saver and how many minutes of inactivity before it kicks in.