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 a black rain warning signal as Tropical Storm Podul skirts the city, with education authorities cancelling morning and whole-day school classes. The Hong Kong Observatory raised the signal at 7.50am on Thursday, meaning that heavy rain has fallen or is...