The remnants of what was once Hurricane Polo continued to drench the U.S. Southwest on Tuesday evening, turning desert roads into rivers and prompting evacuations in small New Mexico communities worried that a dam could give way under the pressure of relentless rainfall.
Polo had already left its mark earlier in the day, slamming into Mexico's Baja California Sur with maximum sustained winds of 110 mph (177 kph). The storm then crossed the Gulf of California, losing strength as it moved inland toward the northeast and degrading into a tropical storm.
The system's weakened state did little to blunt its impact north of the border. By Tuesday evening, the New Mexico Department of Transportation was reporting flooded roads and scattered debris on highways across the state, a sign of how quickly desert terrain can be overwhelmed when heavy rain falls on dry, sun-baked ground.
In neighboring Arizona, conditions were even more severe, with parts of the state described as especially drenched. Several water rescues were carried out as normally dry channels filled with fast-moving floodwater.
The flooding was compounded by storms that had rolled through portions of the Southwest overnight Monday. That earlier round of rain saturated the soil, leaving it unable to absorb the additional downpour and setting the stage for more dangerous runoff.
The concern in New Mexico's smaller towns centered not only on rising water but on infrastructure. Residents were urged to evacuate amid fears that a dam could fail, a scenario that turns a manageable flood into a potentially catastrophic one for communities downstream.
Bands of rain continued to sweep across the region, causing desert rivers to surge and ordinarily dry arroyos to rage with floodwater. These ephemeral channels, common across the arid Southwest, can transform from dusty beds into lethal torrents within minutes.
The scene echoed the kind of flood imagery that has become increasingly familiar in the region, where drought-hardened ground and steep terrain channel rainwater rapidly into low-lying areas, catching drivers and residents off guard.
Polo's path to the Southwest began in the Pacific, where it had reached hurricane strength before making landfall in Baja California Sur on Tuesday morning. After crossing the Gulf of California, the storm weakened to a tropical storm as it pushed inland, but it carried enough moisture to fuel widespread rainfall across the border region.
The storm has been part of a broader pattern of Pacific activity in recent days. Satellite imagery from the National Oceanic and Atmospheric Administration showed Polo alongside Hurricane Odalys and Tropical Storm Nolo off the coast of Mexico, part of a cluster of systems churning in the Pacific while the Atlantic remained unusually quiet.
That contrast has been attributed by meteorologists to El Niño conditions, which tend to suppress Atlantic hurricane activity while energizing storms in the Pacific. The result has been a season in which the southwestern U.S. finds itself repeatedly in the path of moisture drawn north from Mexican waters.
Forecasters warned that the flood risk will not remain confined to the Southwest. Later in the week, that threat is expected to shift into parts of the central United States, with heavy rain projected to hit Texas and Oklahoma beginning Tuesday night, according to the National Weather Service.
That eastward push means communities far from the desert could soon face their own round of flash flooding, particularly in areas where rivers and drainage systems are already stressed by prior rainfall.
For now, attention remains fixed on the Southwest, where emergency crews are monitoring roads, waterways and the vulnerable dam that prompted evacuations. Transportation officials are warning drivers to avoid flooded routes, a reminder that even shallow-looking water can hide washed-out pavement or powerful currents.
The storm's aftermath also raises questions about preparedness in small communities that rarely face such threats. Dam safety, evacuation planning and flood-warning systems are often designed around historic rainfall patterns that may no longer hold as climate-driven extremes intensify.
Polo's remnants serve as the latest reminder that tropical systems do not need to arrive at full hurricane strength to cause serious harm. Moisture carried hundreds of miles inland can produce flooding that rivals the coastal damage of a landfalling storm.
With more rain in the forecast and the ground already saturated, the coming days will test how well the region's infrastructure and emergency systems can cope. Residents in the affected areas are being urged to stay alert, heed evacuation orders and avoid travel on flooded roads until the waters recede.
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