Valley dodges storm

Tuesday, Aug. 9, 2005 | 11:21 a.m.

Southern Nevada's air is hot and humid, but the extra "juice" in the atmosphere failed to bring storms and the flash flooding that had been feared in the Las Vegas Valley's urban areas Monday.

An active thunderstorm bringing plenty of lightning, thunder and a trace of rain swept from Mesquite, northeast of Las Vegas, through the valley and exited southwest early this morning. The storm thundered into the valley at 11:53 p.m. Monday.

A trace of rain fell at McCarran International Airport, where official weather records are kept, National Weather Service forecaster Stan Czyczk said today. Winds gusted to 25 mph during the storm.

Czyczk said thunder and lightning may have awakened some valley residents, but it did not cause any flooding in the valley.

Two Regional Flood Control District rain gauges, one in the northeast valley and the second in the Flamingo Wash at Nellis Boulevard, recorded 0.12 of an inch.

The Lakes Detention Basin in the west of the valley captured 0.08 of an inch.

Thunderheads towered over the mountain ranges ringing the valley all day but never dropped any moisture until late Monday night.

The storm packed 50-mph winds, lightning and some rain in Mesquite, about 60 miles northeast of Las Vegas before midnight.

But for most of the county, there was nothing. The National Weather Service had canceled a flash flood watch for all of Clark County by 9 p.m., instead of leaving it in place as expected until midnight.

The National Weather Service issued a short-term flash flood warning this morning for areas south of Hoover Dam by Lake Mojave because of heavy storms rolling through the area. The warning was expected to be lifted by midday.

Weather Service forecasters said Monday night that monsoon moisture flowing northward from Mexico will continue to bring the threat of thunderstorms to the valley in the afternoons and evenings through mid-week.

Temperatures are expected to remain below normal -- 103 degrees -- as was the case Monday with a high of 98 degrees.

So why is it so hard to bring a thunderstorm into the valley this summer?

Climatologist Kelly Redmond at the Western Regional Climate Center in Reno said that the blanket of moisture that normally rides the winds northward from the Gulf of California hasn't delivered this year.

"This time of year, it's the little features in the weather that matter," Redmond said, such as the amount of moisture in the monsoonal air moving through Mexico. And that amount of moisture in this summer's monsoon season have been skimpy.

In addition, the mountains surrounding Las Vegas protect the valley from too much stormy weather.

The storms popping up over Southern Nevada's mountains act like popcorn kernels dumped into hot oil, he said. The kernels are the clouds and the hot oil is the daytime heating.

Sunny skies in the morning heat the air in the valley enough to provoke an afternoon thundershower. But morning clouds reduce heating and stop thunderstorms from forming in the valley, he said.

"If you get a storm started, it could drop quite a bit (of rain)," Redmond noted, after reviewing humidity levels in the high 20 and 30 percent range throughout the valley.

However, if some change in the weather moves in from the Pacific Ocean, cutting off the moist monsoon, then temperatures are expected to rise again, Redmond said.

"You're either hot and humid or hot and dry," he said. "Those are your choices. Take your pick."

After July broke and set temperature records with 117 degrees or higher, intense heat may be over for this year, Redmond said.

July usually maximizes daytime temperatures, he said, although a high of 113 degrees on Sept. 1, 1947 is impressive.

"It's Las Vegas, it's summer," Redmond said.