Abstract: Using hourly precipitation and conventional meteorological observation data from seven major stations and 249 automatic weather stations from 2004 to 2013,the spatial-temporal distribution and climate characteristics,evolution trend and circulation background of short-time strong precipitation in Dalian were analyzed.The weather prediction indexes of strong precipitation were established as well.The results indicate that regional short-time strong precipitation events occur normally 2.2-2.3 times per year.This number tends to increase slightly in the southern and eastern parts,remains stable in the central and northwestern parts,while decreases slightly in the north-central parts.It usually occurs during April to October,especially during July to August,generally happening from 02:00 to 10:00.The number of times that short-time strong precipitation occurs shows a clear spatial distribution feature,i.e.,increasing from the eastern to the western and central parts.The highest number occurs in the east-northern part,following by the southern part,and the lowest is in Wafangdian of the west-northern part.In July,the highest number of short-time strong precipitation appears in the northern part,and in August,it is in the eastern part.In other months,it shows strong spatial dispersion characteristics.The thresholds,including mean specific humidity between 925 hPa and 850 hPa,depression of dew-point temperature at 700 hPa,average difference in temperature between 500 hPa and 850 hPa,mean K index,mean height of 0℃ layer,and average thickness of warm clouds,can be used to forecast the short-time strong precipitation in real operation.This paper provides a reference for forecasting the strong precipitation in Dalian.

Key words: Short-time strong precipitation, Synoptic characteristics, Prediction indexes