Tropical Storm Rosa has soaked northwestern Mexico with heavy rains as it neared the Baja California Peninsula, reportedly claiming at least one victim, and was projected to extend into a drenching of the US Southwest.
The US National Hurricane Center said the centre of Rosa, which was a hurricane until late Sunday, should hit Baja California and Sonora late Monday, bringing 7.5 to 15 centimetres of rain.
It's then expected to move quickly northwestward as it weakens, bringing five-10 centimetres of rain to central and southern Arizona and 2.5 to 5 centimetres to the rest of the desert Southwest, Central Rockies and Great Basin. Some isolated areas might see even more precipitation.
Rosa's maximum sustained winds had decreased to 65 km/h as of Monday afternoon, and the storm's centre was about 80 kilometres west-northwest of Punta Eugenia in Mexico. It was heading north-northeast at 17 km/h.
The Civil Defense agency for Baja California state said schools would be closed in several communities, including the state capital of Mexicali, across the border from Calexico, California; San Felipe, on the northern Sea of Cortez; and south of Ensenada, on the peninsula's Pacific coast.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Federal authorities declared a state of emergency for Ensenada and Mexicali.
Classes were also suspended in communities in Sonora, where Civil Defense officials advised people to avoid driving on the coastal highway. The agency posted video online of floodwaters racing through and covering a stretch of road, carrying trees and logs in the current.
Various Mexican media outlets reported that a woman was swept away by floodwaters and drowned in the city of Caborca, Sonora, on the Sea of Cortez.
The National Weather Service earlier announced flash flood watches through Wednesday for areas including southern Nevada, southeastern California, southwestern and central Utah and the western two-thirds of Arizona.
Forecasts call for heavy rainfall in the watch areas, which include Las Vegas, Phoenix and Salt Lake City, with possible flooding in slot canyons and normally dry washes and a potential for landslides and debris flows from recent wildfire burn scars.
National Weather Service meteorologists in Phoenix said central and northern Arizona stood to get hit with the heaviest amounts of precipitation.
Metropolitan Phoenix, where temperatures were above 38 Celsius only a few days ago, had already cooled thanks to Rosa. Moisture associated with the storm arrived ahead of it, bringing rain Sunday night and Monday morning. Phoenix meteorologist Jaret Rogers said more showers were expected across central Arizona later in the day before a weakened Rosa arrives in the area Tuesday morning.
According to the National Weather Service, the entire Phoenix area is expected to see between 2.5 and five centimetres of rain. But some areas could see between five to 7.5 centimetres).
"All that means is conditions are favorable for flash flooding if it rains," Rogers said. "It doesn't mean something's imminent."
