This story has been made freely available as a public service to our readers. Please consider supporting SCMP’s journalism by subscribing.The Hong Kong Observatory has issued the amber rainstorm warning, advising residents to brace for wet weather under the influence of a low-pressure trough along the southern Chinese coast.The forecaster issued the lowest of a three-tier rainstorm warning at 11.10am on Sunday, signalling widespread heavy rain would affect Hong Kong soon.The signal means that...