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I CAN'T SEE CLEARLY NOW: Mystery haze fills LV Valley

Keith Rogers

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Experts unsure of cause for grayish skies

A grayish-white sky shrouded the Las Vegas Valley on Monday, obliterating the view of the Spring Mountains to the west and much of the Strip.

But meteorologists for Clark County's air quality program and the National Weather Service couldn't say what caused the haze. They offered theories including suspended dust particles, water vapor transported in a cold front that entered the valley, or smoke and soot particles from wildfires, possibly in Arizona or New Mexico but maybe as far away as Russia.

Photo by Gary Thompson

"I have no idea," said Phil Wiker, the county's air quality meteorologist, when asked what caused Monday's hazy, dim conditions that prompted more drivers than usual to use their headlights.

Wiker said he faced technical challenges because some of the tools that he uses to interpret what's happening with air quality, specifically satellite links and the Internet, were out of service Monday for the air quality monitoring network. The problem stemmed from a Web server malfunction.

He said readings from monitoring stations in the field indicated higher-than-normal fine particulate matter, which sometimes indicates remnants of wildfires that drift into the valley.

As he spoke, the National Interagency Fire Center in Boise, Idaho, which tracks large wild-land fires, listed two each in Arizona and New Mexico.

The closest to Southern Nevada was the 650-acre Twenty-two fire burning in northern Arizona. A 2,177-acre wildfire dubbed Solano was burning in southern Arizona.

Wind direction raised doubts in meteorologists' minds for smoke drifting into Las Vegas on Monday from the two fires in New Mexico, though they were much larger. The Trigo fire in central New Mexico had consumed 13,709 acres of wild land, and the South Tularosa fire in south-central New Mexico had burned 3,860 acres, according to the center's Web site.

Faith Borden, a meteorologist for the National Weather Service in Las Vegas, said a cold front laden with water vapor that entered the valley late Monday morning might have had something to do with the sky's hazy appearance.

"We can't see the mountains, and you can't see down the Strip," she said.

Lack of measurable rain this spring might have allowed Mojave Desert dust to linger after it was kicked up by recent wind storms, she said.

Also, high clouds could have contributed to the hazy look, she said.

Automated readings put visibility at 10 miles around the valley, but it was probably more.

Although the federal government has not set visibility standards, the Clean Air Act requires metropolitan areas to monitor it. Nationwide, visibility is generally considered good if it's 32 miles or more. For aesthetics, rather than for air quality reasons, any visibility reading less than 10 miles is considered poor.

Wiker said some of the hazy conditions in Las Vegas over the past few weeks might have been caused by aerosols generated by major wildfires in Russia.

"We were getting the effects of that earlier," he said.

The Associated Press reported April 24 that smoke from the Russian wildfires and dust from sandstorms in Mongolia's Gobi Desert caused hazy conditions over a wide swath of Alaska, from Fairbanks to Kodiak and from Valdez to the Aleutian Islands.

Seven years ago, in April 2001, dust from a Gobi Desert sandstorm cast a haze over the Las Vegas Valley after it was carried 7,000 miles by high-altitude currents.

Contact reporter Keith Rogers at or 702-383-0308.