Rosa puts 12 million under risk of flood

Tropical storm threatens Southwest

The remnants of Hurricane Rosa are forecast to bring heavy rain and the threat of flash flooding to the Southwest over the next few days.

The now-tropical storm – which had been as strong as a Category 4 hurricane – was poised to make landfall along Mexico’s Baja California Peninsula on Monday evening, where heavy rain was already being reported.

Flood watches are in effect across

A man tries to dislodge debris from a wash on Monday in Tucson. After making landfall in Mexico, Tropical Storm Rosa was expected to drench the U.S. Southwest through the first part of the week.

portions of California, Arizona, Nevada and Utah, including the cities of Phoenix, Las Vegas, Flagstaff and Salt Lake City. More than 12 million people are at risk of flooding, the National Weather Service said.

Arizona should see the heaviest rain, the National Hurricane Center said, where up to a half-foot of rain is possible in some areas. This could bring “lifethreatening flash flooding” and “dangerous debris flows and landslides,” the

RICK WILEY/ ARIZONA DAILY STAR

hurricane center said.

Flash floods are caused by heavy rain. They can turn otherwise calm dry washes, burn scars and urban areas with poor drainage deadly. Last year, a peaceful swimming hole turned into a raging waterway in Payson, killing 10 family members.

Northern Arizona could get 2 to 4 inches of rain the next two days, while Phoenix should expect 2 to 3 inches. The rain will be coupled with gusty winds and blowing dust in some areas.

In some desert areas, the rain that’s expected to fall from Rosa is as much rain as would typically fall in an entire year, AccuWeather said. Yuma, the USA’s driest city, with only about 3.6 inches of rain a year, may see nearly that much the next couple days.

Although flooding is a serious concern, some of the rainfall will probably be beneficial since the Southwest is experiencing drought conditions, weather.com said. According to the U.S. Drought Monitor, more than 40 percent of Arizona is experiencing at least extreme drought, the second-highest category.

The storm may also mark the end of 100-degree days in the Valley, said National Weather Service Meteorologist Andrew Deemer. Historically, Sept. 29 marks the last day of temperatures over 100. Temperatures will stay below average in the low and mid-80s for the first part of the week. They are expected to return to the normal upper 80s and low 90s in the latter half of the week.