8月份的汽车销量暴跌，这可不是个好兆头。Ominously, car sales slumped in August.已经有问题了，这不是好兆头。Already there were problems. It didn't augur well.有刮台风的兆头.There was a threat of typhoon....

“兆头”的英语可以翻译为：omen ...