Bitbucket pipeline triggered from Jira Issue status update?

I have a CI/CD process set up happily and linking Jira and Bitbucket, and the pipelines are triggered on pushes/merges to the git branches.

However I’m looking to trigger a bitbucket pipeline when an issue in Jira is updated. For example:

  1. Jira Issue ISS-1 has a status of ‘In QA’
  2. A QA engineer tests the issue and passes it, changing the status in Jira to ‘Passed QA’
  3. At this point I’d like Bitbucket to run a pipeline based on the update to the status field, which automatically merges branches and deploys to a UAT environment.

I’m happy with how to do the merge/deployment, but it’s triggering the pipeline build from a Jira Issue status change that I can’t work out how to do. Can anyone please enlighted me? I’ve looked at Webhooks, but can’t understand how to use them for this purpose.

Many thanks,