Michael:
I have half an answer for you. You will need to wait until someone smarter than me chimes in with the other half.
WeatherCat version 2.0.0 and later will run on computers running Mac OS X version 10.7.5 or later (Intel only) so you cannot run it on your old computer. I think your best bet may be to update WC to 1.2.4 on your old machine, migrate to your new machine and then purchase WC 2.4.
I have migrated WeatherCat twice to new hardware and done it manually both times. I have never had a totally happy experience with Migration Assistant but it is theoretically supposed to work. Here are the instructions I followed for moving a WC installation from one computer to another, They come from a wiki article, but the link to that article appears to me to be broken. You can scroll through the instructions (up and down as well as left and right so you can see everything):
There are times when it is necessary to relocate your WeatherCat installation from one computer to another. If you are upgrading your Macinitosh the OS-X you can use the migration assistant that comes with OS-X to do this for you automatically. Otherwise you can follow this procedure.
# Place a copy of the ''WeatherCat'' application folder in the target computer's ''Application'' folder.
# Also be sure to install the correct drivers for your station or USB to serial converter* on the new machine before running WeatherCat.
#*Note: WMR200, WH1080/2080/3080 stations do not need drivers to work with WeatherCat.
# If you are running OS X 10.7 or later, the Library folder is hidden. You can make it visible again via the following terminal command:''chflags nohidden ~/Library/''. Another way to make this folder visible is to hold down the Option key while clicking on the Go menu in the Finder.
# Copy the following folders from the source computer to the target computer, placing them in exactly the same file location as on your source computer:
#*''~/Library/WeatherCatData''
#*''~/Library/WeatherCatBackups''
#*''~/Library/Application Support/WeatherCatCustomWeb''
#*''~/Library/Application Support/WeatherCatMedia''
#*''~/Library/Application Support/WeatherCatTemp''
#*''~/Library/Application Support/WCWeb''
#*''~/Library/Preferences/com.trixology.weathercat.plist''
#*''~/Documents/WeatherCatExports''
#*''~/Documents/WeatherCatReports'' <br /> (where ~ is your home directory). Not all of these folders may be present depending on your WeatherCat configuration.
# If you are using any integration software (for example WeatherCat AppleScripts) you must copy them from your source to target computer and place them in the same directory structure as you have on your source computer.
# If you are a Davis weather station user and have needed to use Davis's own WeatherLink software to make adjustments to your console or Weather Envoy, then you should copy the WeatherLink software also to your target computer.
# Move the files associated with your custom website if you have one running. Usually this means moving a folder with a name like: ''WC Custom Web Templates'' and a corresponding folder that by default is called: ''WeatherCatCustomWeb'' The default location for ''WeatherCatCustomWeb'' is ''~/Library/Application Support'', but since you can set these locations for your computer, you must move these folder to the same location as where you had decided to place them on the source computer for the target computer's installation to work properly.
# If you have been using the iOS WeatherCat app, remember to assign an internal static IP address (DHCP Reservation) to your new computer and forward the WeatherCat ports to the new IP address. Otherwise, the Network settings on the iOS app will not be able to find your new computer.
# Keep in mind this process cannot transfer either your registration key for your copy of WeatherCat or anything stored on your OS X keychain like passwords for FTP and electronic mail servers. Be prepared to enter this information again on the new computer.
This should be sufficient to allow you to move your WeatherCat installation from one computer to another. However, most WeatherCat users customize their setups so that additional files may be necessary on the target computer than what has been listed here. Use common sense and your past experience when migrating WeatherCat.
What I am not sure about is whether or not you need to upgrade to the latest update of WC1 before migrating. It may be that you can migrate your version to Sierra and then upgrade to WC2. Someone else will check in later today and straighten me out.
Note to Edouard: The link to Moving WeatherCat from one machine to another in the Wiki appears to be broken. It may be just me being dumb, but can you take a look?
