2019年3月20—21日吉林一次强降雪天气过程分析

Analysis of a Heavy Snowfall Weather Process in Jilin From March 20 to 21,2019

利用地面观测资料、台站观测资料、NCEP再分析资料等,对2019年3月20—21日吉林省的一次强降雪天气过程进行分析。结果表明:随着极涡冷空气的东移南下,极锋锋区加强,锋区上的偏西急流和中纬度地区的西南气流交汇后向东移动,进入新疆北部,因冷暖空气交绥剧烈,为强降雪天气的出现提供了有利的环流形势;高低空急流的相互作用、低层辐合及高层辐合的配置使得整层上升运动不断加强,再加上地形和锋面强迫抬升,使得垂直运动进一步加强,为强降雪天气的产生提供了动力抬升机制;在吉林省强降雪天气出现的过程中,西南方向的水汽输送强度加强,再加上水汽的持续维持,使得降雪强度不断加大;在降雪天气还没有出现之前,偏东急流是主要的触发机制,在提供水汽供应的同时,还提供触发条件,再加上低层偏北气流的影响,使得不稳定条件较强,有强烈的扰动出现,为强降雪天气的出现了提供了有利的动力条件;地面暖锋是造成吉林省此次强降雪天气的主要原因,中低层锋生过程明显,锋区朝着东北方向倾斜,在地形的影响下使得垂直上升运动加强,强降雪天气出现时段同中低层暖锋锋生的对应关系较好。

Used ground observation data,station observation data, NCEP reanalysis data, etc. to analyze a heavy snowfall weather process in Jilin province from March 20 to 21, 2019. The results showed that: as the polar vortex cold air moved eastward and southward, the polar frontal area strengthened.The westward jet on the frontal area and the southwesterly air flowed in the mid-latitude area meet and then move eastward into the northern part of Xinjiang., which provided a strong circulation situation for the occurrence of heavy snowfall weather;the interaction of high and low-level jeted, the configuration of low-level and high-level convergence made the whole layer uplift continuously strengthened, coupled with the forced uplift of terrain and fronts, making the vertical movement. It was further strengthened to provide a power lifting mechanism for the generation of heavy snowfall weather;in the process of heavy snowfall weather in Jilin province, the water vapor transported intensity in the southwest direction was strengthened,and the continuous maintenance of water vapor made the snowfall intensity continued to increase;Before the weather appeared,the easterly jet stream was the main trigger mechanism. It not only provided water vapor supply, but also provided triggering conditions.Coupled with the influence of the low-level northerly airflow, the unstable conditions were strong and strong disturbances appeared.It provided favorable dynamic conditions for the occurrence of heavy snowfall;the ground warm front was the main cause of this heavy snowfall in Jilin province. The frontogenesis process in the middle and low layers was obvious, and the frontal area was inclined to the northeast. Under the influence of topography The vertical upward movement was strengthened, and the corresponding relationship between the occurrence period of heavy snowfall weather and the frontogenesis of the middle and low-level warm fronts was good.