FORMATION CONDITIONS OF WARM-SEASON STORM RAINFALL IN PERM REGION

Abstract

The article deals with the issue of the formation conditions and possibility of predicting storm rainfall in the territory of Perm region using atmospheric instability indices. In the course of the study, the spatial and temporal distribution of storm rainfall cases was assessed, as well as the most favorable values of meteorological parameters and synoptic situations contributing to rainfall were determined. The instability indices were calculated based on the ERA-Interim reanalysis of the spectral model of the European Center for Medium-Range Weather Forecasts (ECMWF) and the reanalysis of the American hydrodynamic model Climate Forecast System (CFS). On the basis of correlation analysis, the dependence of instability indices on the amount and average intensity of storm rainfall was estimated. The critical values of the considered instability indices were determined and corrected in relation to the studied territory. The study showed that the most frequent storm rainfall is observed in June and July in the afternoon and evening. It was found that storm rainfall is mainly associated with the passage of cold fronts. The assessment of the quality of instability indices has shown the feasibility of their use for the forecast and diagnosis of storm precipitation, including in the gradation of this dangerous phenomenon.