This story has been made freely available as a public service to our readers. Please consider supporting SCMP’s journalism by subscribing. New users who download our updated app get a seven-day free trial. Hong Kong’s weather forecaster has issued an amber rainstorm signal, warning that flash floods may hit some low-lying and poorly drained areas. The Hong Kong Observatory raised the warning at 7.30am on Tuesday, which means heavy rain exceeding 30 millimetres has fallen or is expected to fall...