This is the sting in Alfred’s tail. These storms are drawing down very warm, moist air from the Coral Sea in the north. If you happen to be under one of these slow-moving thunderstorms, they are getting ready to dump a lot of rain. The situation is very volatile, as the atmosphere is very unstable.

A slow-moving tropical storm crossed islands off Australia’s heavily populated eastern coast late Friday, lashing coastal suburbs with destructive winds and dumping heavy rain across the region.