Tropical Storm Polo is forecast to drench parts of the southwestern United States with heavy rain and flash flooding after crossing Mexico, according to the National Hurricane Center on Tuesday.
Polo weakened from a hurricane to a tropical storm Tuesday before dissipating over northwest Mexico that night. Even as the system faded, forecasters said more than 30 million people from Arizona to Iowa could face flash flood risks from its remnants as they sweep inland.
Southern New Mexico was already dealing with high water, with some roads flooded and drivers briefly stranded until waters receded.
In Doña Ana County, intense rainfall Tuesday pushed the McLeod Dam to the brink of failing. The National Weather Service issued a flash flood emergency, and county officials ordered evacuations in the area. A county spokesperson said pumps were being deployed to move water downstream and reduce pressure on the structure.
More than 60 flash floods were reported across the Southwest from Monday into Tuesday night, with localized rainfall rates up to 4 inches per hour.
Maps show Tropical Storm Polo path
Polo first came ashore in Mexico’s Baja California Sur as a hurricane, moving northeast at about 23 mph. It then crossed the Gulf of California and made a second landfall in Sonora, the hurricane center said.
By Tuesday night, maximum sustained winds were near 35 mph. The storm’s remnants were expected to continue into the Southwest, nearing El Paso on Wednesday morning before tracking northeast.
Flash flood watches
Flash flood watches stretch more than 1,200 miles from Phoenix, Arizona, to Des Moines, Iowa. More than 14 million people are under the threat of significant flooding.
The Weather Prediction Center warned of a significant flash flood threat from the Four Corners region east into the Central Plains.
Meteorologist Rob Marciano highlighted Albuquerque, New Mexico, as a particular concern where rain may be saturating. The desert city could see around 2 inches. He said Polo’s remnants are interacting with other weather systems, elevating flood risks through the week.
Farther north and east, rain in southern Colorado and along parts of the I-35 corridor is expected to linger into Wednesday. Texas, including Dallas, may see rain through Thursday, with some areas potentially topping 7 inches.
An active Pacific region with Tropical Storm Polo
Before weakening and dissipating, Polo fluctuated between Category 4 and Category 5 strength. It underwent extreme rapid intensification, with winds jumping by at least 58 mph within 24 hours.
From Sept. 21 to Sept. 22, winds surged from 45 mph to 150 mph. The hurricane center called the intensification “truly remarkable.” Over the weekend, sustained winds peaked at 180 mph, tying 2009’s Hurricane Rick as the third-strongest on record in the region. Its central pressure ranked it the second-strongest hurricane on record in the Eastern Pacific, behind 2015’s Hurricane Patricia.
Forecasters noted warm ocean waters, abundant moisture, and reduced wind shear across the basin, with unusually strong El Niño conditions contributing to the uptick in tropical cyclone activity.
Another recent system, Hurricane Nolo, passed the Island of Hawaiʻi over the weekend, bringing heavy rain and strong winds to the state. While Polo’s remnants will not affect Hawaiʻi, island travelers with plans to the Southwest and Central Plains should monitor forecasts and check with airlines for potential weather delays.
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