Manually grab one using Activity Monitor - the problem with auto generated reports is they include information for every process running on your system and tend to be huge.
However, this is just at the point when WeatherCat will try to open the connection to your station so it'd be worth checking for an updated driver for your serial to USB converter. You'll need version 2.3 for 10.10 - try reinstalling the driver (or updating it if running an older version).
Once you've done this, launch WeatherCat in safe mode (hold down the ctrl key just after double clicking it in the Finder), then from the Tools menu select 'Configure Comms'. When you next launch it, you'll be at the station comms window in WeatherCat - check your comms port is listed correctly, if it is select it and your station and see if it'll connect.
