Recently, Beijing experienced a snowfall event described by meteorologists as a “textbook example” of return-flow snow. Return-flow snow occurs when, after a strong cold air mass moves southward, moist air from the east or southeast flows back from the Bohai Sea region into North China, colliding with lingering cold air and triggering snowfall. This recent event exhibited classic characteristics: an initial surge of cold air sharply lowered temperatures in Beijing, followed by a return flow of maritime moisture that was lifted by the Taihang and Yanshan mountain ranges, initiating snowfall first in western and northern suburbs before gradually spreading eastward into the urban core. The process featured clear moisture transport, a distinct boundary between cold and warm air masses, and terrain-dependent snow distribution—hence the “textbook” label. Such snowfalls are typically light but prolonged, impacting transportation and urban operations while also alleviating dry conditions typical of late winter and early spring. Authorities advised residents to monitor short-term forecasts for travel planning.The accurate prediction of this return-flow snow event also highlights advances in China’s numerical weather prediction models and observational systems, enhancing the ability to understand and respond to complex winter weather phenomena.
近日，北京出现了一场被气象专家称为“教科书式”回流降雪的天气过程。所谓“回流降雪”，是指在冷空气南下后，偏东或东南方向的暖湿气流从渤海湾一带反向回流至华北地区，与残留的冷空气相遇，从而形成降雪。此次过程具备典型特征：前期强冷空气控制北京，气温骤降；随后，来自海洋的湿润气流沿太行山和燕山地形抬升，在北京西部和北部山区率先形成降雪，并逐渐向东扩展至城区。整个过程水汽输送清晰、冷暖交汇明显、降雪分布具有明显的地形依赖性，因此被形容为“教科书式”。此类降雪通常强度不大但持续时间较长，对交通和城市运行有一定影响，但也有效缓解了冬春之交的干燥气候。气象部门提醒公众关注临近预报，合理安排出行。此次“回流降雪”的精准预报也体现了我国数值天气预报模式和观测体系的进步，有助于提升对复杂冬季天气系统的理解与应对能力。
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