This form of weather is so significant at Lethbridge that the instrument landing system at the Lethbridge airport is designed primarily to deal with it. Convective precipitation Convective storms or showers provide significant precipitation during the summer months, accounting for about 40 per cent of summer rainfall. The amount of rain produced by any shower can vary greatly. In some cases the rain evaporates before it reaches the ground, and in other cases it will be substantial as in the case of thunderstorms. The rainfall amount and its intensity can vary greatly over short distances.
Heavy showers can produce both significant runoff and soil erosion.
The moisture source for convective storms is that moisture contained by the air mass and that evaporated from the earth's surface or transpired by vegetation. Summer thunderstorms are created by heating of the air in contact with the ground. This warm air rises and cools. If the lifting process continues long enough, precipitation will occur. Topography can play a role in creating showers.