NUMERICAL FORECAST OF SUMMER PRECIPITATION OF DIFFERENT INTENSITY USING THE WRF MODEL AND ATMOSPHERIC INSTABILITY INDICES

Abstract

The paper studies the possibilities of using modern approaches to forecasting summer precipitation of different intensity such as numerical modeling with the WRF model and the use of atmospheric instability indices (CAPE, CIN, LI) calculated based on the model outputs for the territory of the Urals. The instability indices were determined both at the location of the weather station (at the nearest grid node) and by calculating the maximum and average values in the buffer zone of the weather station with a radius of 50 km. The quality of numerical forecast of summer precipitation of different intensity at a grid step of 3 and 9 km was evaluated. The possibilities of using instability indices in forecasting precipitation of different intensity for the territory of the Urals were assessed. The measurements of 12-h precipitation amount in July 2020 at weather stations located in Perm Territory, in the Sverdlovsk, Chelyabinsk, and Kurgan regions as well as in the republics of Udmurtia and Bashkortostan served as verification material. We propose a new approach for predicting the presence or absence of precipitation at a forecast point based on the forecast fields of 12 h accumulated precipitation amounts, which demonstrates higher success rates compared to other approaches considered. The results of the study indicate a satisfactory quality of the forecast of precipitation of varying intensity (except for very heavy precipitation) with the use of the WRF model. It is shown that increasing the step of the calculation grid does not lead to an increase in the quality of precipitation forecast. Recommendations on the use of model forecasts in operational practice are formulated.