Create script to seamlessly retrieve airport weather information

Write a script that can be fired from a url link that will open aviation website, log in to the website with my user ID and password, automatically click some links and navigate to another page, enter the four letter code of airport, click a link to display the airport weather forecast and then display the forecast. This needs the happen seamlessly, without webpages reloading. It must not rely on which web browser is in use on the computer, it must work on windows and Mac. I expect you would use XMLHTTRequest. The link to click will be something like [login to view URL] It does not have to be PHP, as long as it works seemlessly without secuurity warnings or unwanted pop ups. Th script must have error handling built in. YSSY is the code letters of the airport name (Sydney Airport). The aviation website is : [login to view URL] What am I trying to achieve here is a single click to replace 10 or 12 tedious clicks and typing.