Storms don't typically cause trees to develop deep roots, but moderate rainfall and light winds are necessary for the development of tap roots. Trees with shallow or damaged root systems, such as those growing in urban areas, are frequently damaged by storms.
Most of a tree's root system is located 18 to 24 inches under the top layer of soil because oxygen and water is readily available at this depth, while tap roots extend much deeper into the ground. Deep tap roots typically develop in forests and other areas where water isn't readily available.
Trees that are watered regularly with an irrigation system don't develop deep tap roots, while trees in the forest may develop them in an effort to receive enough water for survival. Water is absorbed into the soil during and after storms. This assists in the development of stronger tap roots in areas with proper soil conditions.
Strong storms with high wind speeds and torrential rainfall may cause trees to uproot and fall over in urban areas. When soil becomes saturated it becomes less compact and the roots become exposed and unstable. After the soil has been saturated, high wind speeds are capable of uprooting even healthy trees. Wind, however, does allow trees to become stronger. Mild or moderate wind and regular rainfall promotes a healthy root system and helps thicken the bark on trees, which may help prevent damage over time.