In photos: Tropical Storm Hilary's heavy rains flood California streets
Tropical Storm Hilary's intense rains were flooding roads in Southern California and posing a threat to much of the U.S. Southwest overnight after crossing the border from Mexico on Sunday.
The big picture: California is in a state of emergency due to this extremely rare event that's caused thousands of flights to be delayed or canceled. Climate change has increased the likelihood and intensity of heavy rainfall that can cause catastrophic flooding, studies show.
Editor's note: This article has been updated with more photos and additional information on the storm.