The results show that the late northward-jumping of the subtropical high is caused by the exceptional deep trough of East Asia, the East Asian subtropical upper westerly jet and the weak ITCZ.

• 结果表明，入梅前，东亚大槽发展强盛，ITCZ偏弱以及东亚副热带高空西风急流强劲少动导致西太平洋副热带高压北抬偏晚。