Local dynamic factors and hailstorms occurrences

Abstract

Hail precipitation swells are common in tropical and/or subtropical climate regions, as they usually occur in environments with high atmospheric instability and greater temperature ranges. In this sense, the search for understanding the causes and effects of this type of precipitation for society is fundamental, since it can help in the definition of strategies to mitigate negative impacts. Therefore, this study aimed to relate the amount and size of hails with five influential factors in the occurrence of this type of precipitation: time, temperature, season, types of storms (isolated or organized) and the amount of rain (mm). The research was conducted from January 2018 to December 2020 in the municipality of Laranjeiras do Sul, State of Paraná, Brazil. In all, data from seven events were collected. The methodology relied on the use of tools such as analog rain gauge, pocket thermometer, calipers, and radar images obtained from Meteorological System of Paraná (SIMEPAR). The data were organized in tables for each event and basic statistical analysis was performed. The results indicated that the largest amounts of hail precipitated when the air temperature was around 18 ºC, with average rainfall greater than 1mm/min and with gale. As for the sizes, it was noticed that hails larger than 20 mm in diameter occurred preferably on warmer days in winter, with temperature around 20.8ºC.