Most severe thunderstorms form when humid north-easterly air converges with drier northwesterly airflows.大多数强雷暴都是在潮湿的东北风与较干燥的西北气流交汇时形成的。We headed off in a northwesterly direction.我们向西北方向进发。The storm is headed in a northwesterly direction.暴风雨向西北移动。We sailed northwesterly.我们向西北航行。