You have not heard thunder until you experienced it in Yosemite Valley. Similarly, you have not seen lightning until you have seen the sky lit up above San Luis.
Thunder and hail storms appear out of nowhere and quickly. Not sure if it is the desert weather, the nearby Sierras and the proximity to the Andes, though somehow the storms are violent in nature.
Strong wind gusts, buckets of water, or worse, hail (piedras). People are terrified when it starts hailing. Hail can be as big as golf balls or lemons. No wonder folks will look for shelter under a tree, a gas station or anything that will protect them and their car from the hail.
It is furthermore incomprehensible how a city the size of San Luis, lacks a drainage system. Thus, when the skies open, the streets turn into ranging small rivers.