Trevelin ground for long periods of time. Winters are stormy with frequent rain, sleet and snow while summers are cool, windy and relatively dry. Mean annual precipitation is . The precipitation pattern resembles a Mediterranean one, where most (75%) of the precipitation is concentrated from April to August, the cooler months with a dry period from September to March. Snowfall can occur during the colder months while rainfall predominates in warmer months; hail rarely occurs. The mean temperature in Trevelin ranges from in July, the coldest month to in January, the warmest month. Frosts can occur at anytime, even in summer,
Hail the hail to the radar, and the echo is further away from the radar than the actual location of the hail on the same radial path, forming a cone of weaker reflectivities. More recently, the polarization properties of weather radar returns have been analyzed to differentiate between hail and heavy rain. The use of differential reflectivity (formula_1), in combination with horizontal reflectivity (formula_2) has led to a variety of hail classification algorithms. Visible satellite imagery is beginning to be used to detect hail, but false alarm rates remain high using this method. The size of hailstones is best determined by