Enhancing operational weather prediction efficiency in the context of a hail suppression program

The regions of Central Macedonia and Thessaly are the main areas of dynamic fruit tree cultivation in Greece. At the same time, the aforementioned areas are also largely affected by extreme weather events such as intense thunderstorms, frequently accompanied by hail. Crop damages attributed to hail reach several million euros per year.  For this reason, the Hellenic Agricultural Insurance Organization (ELGA) performs, for over thirty-five years, the National Hail Suppression Program (NHSP) to mitigate crop damages. The core ingredients of the hail suppression program that have to be in perfect coordination are the meteorologists of ELGA’s Center for Meteorological Applications (KEME), the surveillance weather radars and the seeding aircrafts (provided by a private company). Since 2018, the daily operational forecasts issued by KEME’s meteorologists have been supported by the results of a numerical weather prediction system focusing on the protected areas. The system is based on the non-hydrostatic Weather Research and Forecasting (WRF) model with the Advanced Research (ARW) dynamic solver. Using three nested model domains, the grid spacing over the protected areas reaches 1.6km (Central Macedonia and Thessaly). The outer model domains cover Europe and the Mediterranean Sea at 15km and Greece at 5km grid spacing. This research aims to present the operational use of the numerical weather prediction system, its integration in the everyday prediction and finally to highlight its advantages and shortcomings that became apparent during the eight years of its extensive use.  Days of “good” and “bad” performance are isolated and common characteristics leading to this performance are identified.