Odile will unload tremendous rainfall over a large part of the Southwest United States that will run off the mountains and into the desert valleys and plains through the end of the week.

According to Western Weather Expert Ken Clark, “There is the potential for devastating, catastrophic and historic flooding in this scenario.”

The heaviest rainfall will hit the Southwestern states of Arizona and New Mexico where a general 3 to 6 inches will fall, but local amounts of 10 inches or more are possible on the slopes of the mountains. Rainfall of 1 to 2 inches per hour can occur.

There is a significant risk to lives and property in the region.

“Not only will flash and urban flooding occur in this case, but there is the potential for major river flooding,” Clark said.

This is the type of threat that can cause water to sweep through normally dry stream beds, calledarroyos, and into villages, towns and major cities rapidly. Major roads can be damaged and some bridges along secondary roads could be swept away. Mudslides and dust storms can block roads in a few locations.

“Travel on Interstate-10 between El Paso, Texas, and Phoenix will be dangerous,” Clark said.

A safer route from the Plains to California will be I-40, but delays and poor visibility are possible due to heavy rain.

The rain from Odile is coming just one week after moisture from Norbert drenched the region, creating major flooding.

Some areas around Phoenix and Las Vegas are still cleaning up.

Norbert caused a daily record rainfall of 3.29 inches at Phoenix earlier in September.

The combined rainfall from Norbert and Odile has the potential to cause September to be the wettest month ever in some areas. For example, during August of 1955, 7.9 inches of rain fell at Tuscon, which set the mark for the wettest month since records began in 1895. Thus far this month, about 2.5 inches of rain have fallen at Tuscon.

Cities that could be affected by the heavy, flooding thunderstorms include Phoenix, Flagstaff, Tucson and Yuma, Arizona; Albuquerque, New Mexico; and El Paso, Texas.

Spotty, heavy thunderstorms can reach as far to the north and west as Las Vegas, Palm Springs, California, and Salt Lake City, Utah.

“The greatest risk of widespread flooding in the Southwest will be from early Wednesday morning into Thursday night,” Clark said.

“However, spotty heavy showers and thunderstorms will continue, especially over the higher terrain, into the weekend and can lead to additional flooding in isolated areas.”