But seeing that toppled billboard made me realize that even though this was not a hurricane and instead was just part of the 10% to 20% chance of rain that day, thunderstorms can cause serious damage even if the winds don’t reach hurricane strength.

A mature oak tree can remove over 100-gallons of water per DAY!  That's a lot of water.  Since expansive soils shrink and swell depending on their moisture content, you can easily see how trees can wreak havoc on a foundation.