THE DEVELOPMENT OF A MODEL-ALGORITHM FOR PREDICTING HAILSTORMS IN CENTRAL MACEDONIA, GREECE

Abstract

The objective on this study is to create a model-algorithm, in order to predict-forecast hailstorms in the area of central Macedonia-Greece, where the Greek National Hail Suppression Program is conducted. The examined time period is from April to September, for the years 2008, 2009 and 2010. The data used were obtained from the C-band weather radar being located next to the area of interest, weather charts and the daily atmospheric soundings, being launched at the synoptic station of Thessaloniki and analyzed from the University of Wyoming, USA. The adopted methodology relies upon the weighted and nonlinear multiple regression analysis theory, where certain functions of the correlation values between the dependent variable and each one of the independent variables, were used for the determination of the weighted coefficients. As dependent variable was used the observed -by the weather radardaily maximum reflectivity values. On the other hand, eight (8) independent variables were chosen, through the statistical analyses of twenty-six (26) instability, microphysical and thermodynamic parameters, in order to form a stable, nonlinear, model-algorithm. In general, the adopted independent variables describe the thermodynamic and dynamic characteristics, together with instability factors and the precipitable water, of the encountered hailstorms. The algorithm was developed based upon the exploratory set of data information and it was statistically evaluated by using the confirmatory set of data. The evaluation procedure proved that the developed nonlinear model-algorithm is a reliable and useful tool of predicting and forecasting hailstorm activity in the examined area of Central Macedonia, Greece.