It may have been downgraded, but Tropical Storm Rosa is still going to have a big impact on northern Mexico and the southwestern United States, reports USA Today.
At one point, Rosa was classified as a Category 4 hurricane, but it is now listed as a Tropical Storm, and is expected to make its first landfall in Baja California — Mexico’s far western peninsula. The storm is expected to touch down on Monday night, with residents of Baja California already reporting heavy rainfall.
Flood watches have been issued by the National Weather Service in the states of Arizona, California, Nevada, and Utah. That puts more than 12 million people at risk of the flooding that the storm will bring, with a flood warning being issued for almost all of Arizona.
Arizona will see the worst of the storm, where rain is expected to reach at least six inches in some areas. The National Hurricane Center warns that the floods will be life-threatening and could also trigger landslides in the path of the storm.
Flash flooding is not unusual for Arizona, with a sudden flood turning a swimming hole into a virtual raging river in Payson last year, killing 10 people after heavy rain came through the area.
Rain is starting to push into Southern AZ this afternoon beginning several days of flash flood concern as moisture from TS Rosa streams into the region. Water can quickly rise in normally dry creek beds. Avoid low water crossings and turn around, don't drown. pic.twitter.com/2MAhYbedcY— NWS (@NWS) October 1, 2018
With so many desert areas in the path of the storm, the expected rainfall is expected to have a significant impact in some parts of the state. One of the towns in the path of the storm, Yuma, Arizona only sees 3.6 inches of rain a year on average. That number could be doubled in the coming days, which will cause serious issues for residents of the city.
Some of the rain will be useful in the southwest which could, at least temporarily, relieve drought conditions. Approximately 40 percent of Arizona is considered to be experiencing a drought at this time. With drought conditions, the rains will sweep away dry soil much quicker than would normally happen under heavy rains, raising the chance for potential flash floods.
Several schools in Baja California were closed today, with the storm sitting 75 miles west of Punta Eugenia this afternoon, with wind speeds of 45 miles per hour. Cities throughout the area have been making various preparations, on top of helping residents who wish to evacuate the area for their own safety. Many cities in Arizona have been issuing sandbags to any residents that want them to protect their properties, while airlines have issued travel waivers for travel to the southwest.