You can exclude the old files (those on the cloud, but not on the local server anymore) using file mask with time constraint. To prevent them from being synchronized back to the local server:
https://winscp.net/eng/docs/file_mask

Also, do you need two-way synchronization at all? What about doing one way sync only (local server => cloud)?

So here goes, I have yet to develop a script or process for the Idea I'm working through right now. I am developing this process for the company I work for. What I am trying to do is automate uploading of images to our cloud storage. We are taking lots and lots of photo's of our product and pushing them to our cloud.

I am wanting a process that will compare and upload all new images for the day to our cloud but not in reverse. I want them to go from our local server to the cloud, and at the end of the day, or week the files will be removed after syncing. Now when the sync happens I do not want the images re-synced to our local server.

My question is this possible to setup with WinSCP and scripting?

Thank you for any and all help.