2006年1月19日宁夏北部暴雪成因分析

利用常规气象资料、数值预报实况场及卫星云图等资料,应用天气学分析及诊断分析方法,对2006年1月19日宁夏北部暴雪天气过程的成因进行了系统分析。结果表明:高空西风急流、低空偏南风急流、近地面偏东风回流、河套“歪脖子高压”、河套地面锢囚锋的建立和长时间维持以及河西高低空切变线的侵入是宁夏北部暴雪的主要影响系统。这次暴雪的出现,正是低空急流所携带的暖湿气流与低层回流所携带的湿冷空气交汇,同时西路冷空气介入所致。由于东西两路冷空气的夹挤作用,迫使高原东侧的偏南暖湿空气上升,使得上升运动得以加强和维持,为暴雪的产生提供了动力条件,而低空急流及回流存在则为暴雪产生提供了充足的水汽条件。此外,宁夏北部地面风场的中尺度辐合、地形抬升、低层水汽和不稳定能量的积累以及宁夏北部处于3支气流的交汇处,也为这次暴雪产生起了重要作用。

Analysis of a Snowstorm Weather Process in North Region of Ningxia on 19th January 2006

Based on the routine meteorological data,numerical forecast products and FY-2 satellite cloud images,the formation reason for the snowstorm weather event on January 19th,2006 in the north part of Ningxia was analyzed and diagnosed.Results show that this is a typical mixed precipitation process,the main influencing systems are the high level westerly jet,lower troposphere jet,surface layer easterly air flow,500 hPa southwest cold trough,700 hPa low eddy shear line and surface occluded front persisting for long time.The weather situation with the high center in the east but the low center in the west is also the typical pattern of precipitation in winter in Ningxia region.This heavy snow occurred as a result of the warm-humidity and cold-humidity air flows convergence,multi-scale weather systems interacting under a suitable situation,the mountain uplifting ,etc.'and the accumulations of water vapor and the unstable energy also play an important role in this local snowstorm event.