拉尼娜状态持续，预计今冬我国强降温和升温事件将频繁

Core Viewpoint - The current La Niña state in the equatorial central and eastern Pacific is expected to persist until early 2026, with a low probability of forming a significant La Niña event due to its duration being less than five months [1]. Group 1: La Niña State Definition and Duration - The La Niña state is defined by the NINO3.4 index, which indicates that when the three-month sliding average of sea surface temperature anomalies is less than or equal to -0.5 degrees Celsius, it is considered a La Niña state [1]. - The National Climate Center reports that as of December 15, the La Niña state is ongoing, and its duration is currently less than five months, making the likelihood of a significant La Niña event relatively low [1]. Group 2: Impacts of La Niña State - The ongoing La Niña state is expected to lead to colder temperatures in central and eastern China during winter, as the prevailing cyclonic circulation enhances the winter monsoon [1]. - There is a historical trend of warmer winter temperatures in China under La Niña conditions, with instances of warm winters occurring, such as in the winter of 2020/2021 [2]. - The cyclonic circulation may also suppress moisture transport from the northwest Pacific and South China Sea, leading to reduced precipitation and an increased risk of drought during the winter and spring [2]. Group 3: Weather Predictions for Winter - This winter, most regions in China are expected to experience temperatures close to or above the seasonal average, with significant fluctuations and frequent cold and warm events [2]. - Overall precipitation is anticipated to be below average, with a spatial distribution of "more in the north, less in the south" [2]. - Specific regions such as Northeast China, North China, Inner Mongolia, and Xinjiang may experience strong winds, significant temperature drops, and snowfall, while southern regions may face risks of drought due to low temperatures and reduced precipitation [2].