盘锦春季弱降水个例分析及预报指标

Analysis and Forecast Indicators of Weak Precipitation in Panjin Spring

本文选取盘锦地区2013-2018年这5年春季(3-5月)85次弱降水天气过程,通过多个例天气形势、物理量要素的综合对比分析方法,对上述弱降水过程进行统计分析,结果表明:(1)在漏报的26次过程中降水量不足1 mm有21次,≥3 mm的5次。区域性降水漏报4次,局地降水漏报22次。空报12次中两站同时出现空报6次。(2)根据500 hPa高空影响系统的不同弱降水过程分为:高空冷涡型、高空槽型和其他型。按照地面天气系统弱降水过程可以分为以下两种类型:冷锋型和倒槽型。(3)弱降水预报指标:一是对流层中低层水汽。925、850和700 hPa相对湿度>80%,或相邻两层相对湿度>90%。二是判别925、850和700 hPa是否存在上升运动,以垂直速度值的正负号来诊断上升和下沉运动。三层都表现为上升运动时更有利降水出现。(4)分析预报员出现空漏报的主要原因,缺乏弱降水预报订正经验。对近地面层出现弱锋面过境不够重视以及对低层水汽条件的误判。空报过程数值模式都预报有降水,而水汽的预报偏差较大是空报的主要原因。

This paper selects 85 weak precipition weather process in Panjin region spring from(March to May)2013 to 2018,and analyzes the above-mentioned weak precipitation process through the comprehensive comparative analysis of several weather conditions,physical factors and weather science methods,and the results show that:(1)there are 21 precipitations of less than 1 mm and 5 times≥3 mm in the 26 missing processes.Regional precipitation was reported 4 times and local precipitation was reported 22 times.(2)According to the 500 hPa high-altitude impact system,weak precipition weather process is divided into:high-altitude cold vortex type,high-altitude slot type and other types.According to the ground weather system weak precipitation process can be divided into the following two types:cold front type and tank type.(3)Weak precipitation forecast indicators:The first is the middle and lower levels of water vapor in the lysphere.The relative humidity of 925,850,700 hPa>80%,or 90%>adjacent layers.The second is to determine whether 925,850 and 700 hPa have rising motion to diagnose rising and sinking motion with positive and negative signs of vertical velocity values.All three layers show up more favorable precipitation when moving upward.(4)Analysis of the main reasons for the forecaster’s empty report,lack of experience in revising weak precipitation forecast.Insufficient attention is paid to the transit of weak front surface in the near-ground layer and misjudgment of the conditions of low-level water vapor.The numerical model of the short reporting process predicts precipitation,and the large deviation of water vapor is the main reason for the short report.