The problem of summer monsoons in the U.S. with warmer and warmer weather:

fact: warmer air can hold much more water than colder air.

 So, when the monsoons come off of the Pacific Ocean and the Gulf of Mexico like right now up through Mexico and Arizona and New Mexico into Western states and are carried now eastward often  it means things like Kentucky and Denver and Las Vegas and Death Valley can happen more and more without warning to anyone. The weather service might give a vague idea of what could happen but mother nature is by nature very quixotic and irregular in what she puts out especially now in more extreme examples of global climate changes worldwide on a daily basis. 

Monsoons are by their very nature here in the U.S. prone to extreme flash flooding wherever they might hit in force. So, anywhere from parts of California to the East coast need to watch out whether this is in a desert or mountains or wherever it hits. If your ground is presently saturated and one of these things hits anywhere it is likely going to be pretty bad in it's outcome.