Residents across the Southwestern United States braced for heavy rain this weekend, the latest in a two-month stretch of soaking storms that have helped ease drought conditions but also overwhelmed rivers and flooded roadways, homes and entire towns.
A storm system was poised to unleash even more rain across the region on Saturday and Sunday, particularly over parts of Arizona, Utah, Colorado and New Mexico. Flood watches from the National Weather Service were in effect.
“We expect another potential round of flash flooding on a lot of the rivers that experienced flooding a week or so ago,” said David Simeral, an associate research climatologist at the Desert Research Institute in Reno, Nev.
Over several days last week, rain led to widespread flash flooding and road washouts across the Navajo Nation, which straddles Arizona, Utah, Colorado and New Mexico, an area often referred to as the Four Corners.
In Colorado, rain poured over the San Juan Mountains in a storm that Russ Shumacher, the state’s climatologist, wrote this week “should be considered among the most extreme storms in state history.”
Rain coming off nearby mountains flowed into the San Juan River, which reached record levels and caused flooding as it passed through towns from Pagosa Springs, Colo., to Farmington N.M., and Bluff, Utah, en route to Lake Powell on the border between Arizona and Utah.
In Utah, muddy floodwaters gushed down Gould Wash, a normally dry creek, and into the city of Hurricane, damaging dozens of homes. Monica Traphagan with the Weather Service office in Salt Lake City called this a 50-year event for the region; the wash had also flooded, though to a lesser degree, in August.
“The amount of rain we’ve gotten and all the flooding is unusual,” Ms. Traphagan said.
October was wet across the Southwest, and so was September. New Mexico recorded its second wettest September ever, with records dating back to 1895.
The city of Alamosa, Colo., in the San Luis Valley just east of the San Juan Mountains, is typically a dry place, receiving about 7.4 inches of rain each year. So far this month, it has recorded about 3.7 inches — far exceeding its typical October rainfall of about six-tenths of an inch.
“It’s a very dry mountain valley there,” said Kyle Mozley, a meteorologist at the Weather Service office in Pueblo, Colo. “All the precipitation that they’ve had this year has been in the last two months.”
A lot of the moisture has come from far-off tropical storms and hurricanes in the Pacific Ocean. These storms form annually, but this year’s hurricane season, which runs from May 15 to Nov. 30, has been particularly active because of the strong El Niño weather pattern.
The Pacific is “providing an abundant moisture source that are fueling these storms,” said Michael Crimmins, a meteorologist and professor at the University of Arizona.
Though no particular storm can be directly attributed to climate change without further analysis, it fits a general pattern. Warm air can hold more moisture, resulting in heavier rainstorms.
On Saturday and Sunday, the latest storm system over the Southwest will be pulling in moisture from the remnants of the former Hurricane Vance.
Showers are expected to intensify and spread overnight Saturday and into Sunday, when a large portion of the Southwest will be at risk of heavy rain that could lead to flooding.
The latest rain is expected to be focused again over the Four Corners and the San Juan Mountains, which can wring water from a saturated atmosphere and send it pouring into rivers and streams. An area that includes Phoenix and extends toward Grand Canyon National Park is also at a high risk for flooding.
“Overall it’s going to be a very long-duration rainfall event, which is going to be problematic because we’re going to accumulate multiple inches of rain over several hours,” said Matt Salerno, a forecaster with the Weather Service office in Tempe, Ariz.
By Monday, the storm system will have cleared the Rocky Mountains and will be out over the Plains and moving out of the Southwest.
The post After Months of Heavy Rain, the Southwest Faces More Weekend Storms appeared first on New York Times.
