中文摘要：

本文主要介绍低频天气图延伸期预报方法.低频天气图是一种不同于统计学预报方法、数值预报方法和天气学预报方法的延伸期天气过程预报的新方法,可以用于延伸期（10～30天）天气过程预报.低频天气图的技术要点是大气低频系统（低频气旋和低频反气旋）及其相应的低频气流.低频天气图的天气学意义是能反映造成天气过程的天气系统的生消、维持和移动及其大气环流演变过程.其优越性在于其特性：时间上的周期性（30～50天）、持续性和空间上的连续性、相似性以及地域上的准定常性,预报天气系统相对容易且时效长.2008～2012年在上海市气候中心业务应用的结果表明,可以提前15～45天预报上海地区的强降水过程.

英文摘要：

A method of extended range forecasting, the low-frequency synoptic map （LFSM）, is introduced in this paper Unlike statistical forecasting, numerical prediction, and synoptic forecasting, the LFSM is a new approach that can be used for extended range weather process forecasts. The key technical points of the LFSM are the low-frequency system （low-frequency cyclone and low-frequency anticyclone） and the corresponding low-frequency airflow. Its synoptic significance is that the LFSM can reflect the formation, dissipation, maintenance, and motion of synoptic systems that cause weather processes, as well as the evolution of atmospheric circulation. Its advantage lies in its characteristics, including temporal periodicity and persistence, spatial continuity and similarity, and the quasi-steady properties in an area, so the LFSM can easily predict weather processes and has a longer forecast validity period. Operational practice using the LFSM in the Shanghai Climate Center from 2008 to 2012 indicates that it can predict strong precipitation processes 15-45 days in advance.