Overview of Recent Advancements in Convective Storm Nowcasting in the Czech Hydrometeorological Institute

An updated version of JSMeteoView2 web-based application has been developed in the Czech Hydrometeorological Institute (CHMI). It has been used as a primary application for display of weather radar data in CHMI forecasting offices. It is used primarily for displaying of radar data which are available with horizontal and vertical resolution of 0.5 km. It also enables display and combination of other types of data such as data from synoptic stations, data from meteorological satellites, lightning data and requests for intervention of integrated rescue system. Users can use various geographical layers to precisely localize individual meteorological events.

New JSMeteoView2 layer displaying results of object based CELLTRACK algorithm is used specifically in convective situations. CELLTRACK identifies cores of radar reflectivity 44 dBZ and higher and tracks these identified reflectivity cores. It also displays various direct and derived characteristics of the identified cores based primarily on radar data but also on lightning data.

Among other reflectivity core characteristics various hail products were implemented. They are based on Waldvogel algorithm, severe hail algorithm described by Witt and also Vaisala HydroClass algorithm based on dual polarization weather radar data. Long-term evaluation of these hail products was carried out using records from European Severe Weather Database and also on continuous observations from CHMI professional stations, which enabled assessment of probability of detection but also assessment of false alarms occurrence.

The contribution will introduce the updated JSMeteoView2 application with main focus on description of CELLTRACK object layer and overview of implemented hail products. The contribution will also describe methods used for evaluation of hail products and results of this evaluation.