La Nina threatens a real scorcher for Las Vegas this spring, summer

Thursday, May 4, 2000 | 11:05 a.m.

Heat waves are rising, cars are like ovens and the wind feels like a hair dryer in hell.

This isn't your imagination. It's hot out there.

And you better enjoy it while you can.

Weather forecasters say this spring's unseasonably warm temperatures in Las Vegas are just a mild taste of things to come -- this summer is shaping up to be a scorcher.

Go ahead, blame "little girl."

The cool ocean current known as La Nina (little girl in Spanish) is creating a warm air mass over the Southwest that meteorologist Ron McQueen of the National Weather Service says is primarily responsible for the high temperatures in the region since March.

At the same time, the river of air known as the jet stream has been hovering in an unseasonably northern position along the U.S-Canadian border -- effectively blocking cool weather systems from reaching the Southwest.

What it all adds up to, McQueen said, is that instead of waiting until May 27 when temperatures typically hit the century mark, Las Vegans can expect to be sweltering in 100-degree highs as early as next week.

"It is like summer already," McQueen said.

And we all said the same thing about spring back in January.

After all, Southern Nevada's high temperatures this winter ranged from 3 to 5 degrees above normal, according to Kelly Redmond, regional climatologist for the Desert Research Institute's Regional Climate Center in Reno. And this spring, temperatures have ranged from 5 to 10 degrees above normal.

"If you look at the United States, the West is warming more rapidly than the rest of the country, primarily in winter," Redmond said.

Southern Nevada is clearly showing a strong warming trend, an overall average of 3 degrees higher since 1966, he said.

"I don't know what to make of that," Redmond said.

And as temperatures rise in Southern Nevada, water levels drop.

So far this spring, the West's weather is drier than normal, and it is already affecting water supplies. That trend is expected to continue through June.

"Lake Mead will be dropping quite a bit," Bureau of Reclamation spokeswoman Colleen Dwyer said. "From January this year to January next year, it will drop about 11 feet."

But don't start hoarding water yet.

Southern Nevadans don't have to worry about going dry, even if there is an extended dry spell, Dwyer said. Lake Mead, the area's primary source of drinking water, can hold two years' worth of supplies from the Colorado River.

And that's without an instant refill during the annual mid-July monsoon season. The summer wet season cranks up in Southern Nevada when moisture-laden storm fronts push up from the Gulf of Mexico, frequently resulting in the biggest rainstorms of the year, McQueen said.

That was the case on July 8 last year when a powerful thunderstorm pounded Las Vegas, flooding the entire valley. Two people were killed by the storm and $20 million worth of public property was damaged.

"It's hard to say what will happen in regard to summer rainfall," McQueen said.

Computer models at the National Oceanic and Atmospheric Administration's Climate Prediction Center project the heaviest summer rainfall in central Arizona, southwestern Utah and New Mexico, he said.

With warmer air temperatures in the Southwest, McQueen said there is no doubt Southern Nevadans could be seeing more and more intense storms like last year's gully washer.

"They are definitely more violent than they were 20 years ago," he said.

What concerns forecasters is the potential for a storm like the one that dumped 6 inches of rain in Moapa Valley, 45 miles northeast of Las Vegas, in 1981, McQueen said.

Experts believe that crushing cloudburst was partially fueled by moist air generated by the Virgin and Muddy rivers.

"We can't rule out that one day we may see a storm of that intensity in the Las Vegas Valley," he said.

Take your pick, high temperatures or high water, Southern Nevadans may see it all this summer.

Mary Manning covers environmental issues for the Sun. She can be reached at (702) 259-4065 or by e-mail at manning@lasvegassun.com