Tropical Storm Polo will impact the U.S. after slamming Mexico. See its path.

Tropical Storm Polo, once a Category 4 or Category 5 hurricane, is set to impact the southwestern United States after making landfall in Mexico. The National Hurricane Center reported that over 30 million people from Arizona to Iowa could face the risk of flash floods due to heavy rain. As the storm moves northeast at about 21 miles per hour, it has already caused flooding in southern New Mexico, trapping drivers in vehicles.

Polo made its first landfall in Mexico's Baja California Sur and crossed the Gulf of California before making a second landfall in Sonora. It is expected to continue along its current path into the southwestern United States, with potential heavy rain in El Paso and Dallas. A flash flood watch is in effect from Phoenix, Arizona, to Des Moines, Iowa, with more than 14 million Americans at risk of major flooding.

The storm had maximum sustained winds of 65 mph, with winds reaching up to 35 mph when it reaches El Paso.