Nevada tornadoes scarce, but can occur

Mrs. Joe Leavy was sitting on the bed in her home up the road from the Hoover Dam construction site when a mammoth wind on July 24, 1931, shook the house and carried her out a window and into the sky.

Leavy was spirited away on a "magic carpet ride" on her mattress as a twister ripped apart 12 nearby homes and left seven people injured.

She "landed in a heap with the mattress, shaken up but unhurt," according to the seemingly straight account in the Las Vegas Review-Journal.

"Autoists" described the tornado "as bounding along, in zigzag fashion, coming down with its point here and there," the newspaper reported.

Anyone who has lived in Nevada for any period of time knows the Silver State doesn't have tornadoes. Right?

"People in Nevada are more likely to be afraid of rattlesnakes than tornadoes," said Kelly Redmond, regional climatologist and deputy director of the Desert Research Institute. "I have never seen one."

But 79 tornadoes have been observed in Nevada since 1950, according to the National Climate Data Center. Only in Alaska are residents less likely to experience tornadoes.

Nevada tornadoes have injured two people and caused $1.6 million in damage. No one has ever been killed in a Nevada twister. And no recorded Nevada tornado has exceeded the F1 category, meaning winds of less than 112 mph and a funnel 30 yards to 150 yards wide.

That sounds like a big storm, but F5 tornadoes have winds of 300 mph and can be a mile wide. About 80 people a year are killed in the United States in tornadoes. In the 1950s, more than 500 people a year regularly were killed. Tornadoes are considered the most destructive of all atmospheric phenomena.

Spring is when temperatures begin to warm up and storm chasers come out of hibernation to gleefully begin scouting for funnels and destruction.

Tornadoes first are sighted in states such as Texas and Oklahoma in March and April. As temperatures warm up, tornadoes are seen in the Midwest, according to Redmond. Most of the tornadoes in the United States are seen in April through June, according to the Weather Channel.

The last officially recognized tornado in Clark County occurred on March 30, 1992. It tore off the roof and broke windows of a home owned by Keith McKinney about 10 miles south of Las Vegas. It came on a day when 1.73 inches of rain fell on parts of the Las Vegas valley.

Redmond figures Nevada tornadoes are more frequent than the National Climate Data Center statistics show, but most occur in wide-open spots far from people and seldom are seen.

The fact that Nevada rarely has even tiny tornadoes is becoming known. The city-data.com Web site polled its viewers to identify the best state for 80-degree plus days, sunny weather, little rain and few natural disasters. Nevada won in a landslide.

Redmond said Nevada does not have many tornadoes because of its dry climate and north-south mountain ranges.

For tornadoes to form, the atmosphere must be full of moist, warm air near the surface that collides with cooler air in the clouds at higher elevations. But Nevada doesn't often have such conditions. The mountain ranges also block moisture from forming near the surface.

"You also need a thunderstorm, and we don't get the vigorous thunderstorms that the rest of the country gets," Redmond said.

"It doesn't surprise me we never had a fatality in a tornado," said Mark McLaughlin, a Lake Tahoe-area writer who has written books on Nevada weather, including the tale of the tornado near Hoover Dam. "The atmosphere is too dry."

McLaughlin, who studied under the late state climatologist John James, tends to believe the old story.

That week is well known among weather buffs because it was a time when all-time temperature records were set throughout the state. Weather observer Charles "Pop" Squires recorded a 118-degree temperature in Las Vegas that week, and 106 degrees was charted in Reno. Squires' reading was the highest ever recorded in Las Vegas, but is not considered official because it came before the National Weather Service began recording temperatures.

The hot weather could have spawned thunderstorms, and monsoon rains might have come up the Colorado River from Mexico.

If the 1931 story is accurate, magic carpet ride and all, then it was the most destructive tornado in Nevada history.

Reared in Philadelphia, McLaughlin has never seen a tornado.

"They can be pretty impressive when they are large," added McLaughlin, who is not surprised that storm chasers are willing to risk death to approach them.

Rather than tornadoes, Nevadans often see dust devils on hot summer afternoons. Like tornadoes, dust devils are made up of rotating columns of air, but rarely are as intense as tornadoes. They form in sunny conditions as swirling currents of air come into contact with the earth's surface and kick up dust.

Some Arizonans call them sun devils, and people even have been known to refer to them as Nevada tornadoes.

Redmond said he has watched many dust devils, including one that lasted 15 minutes. They have been known to cause minor property damage, but generally are harmless, he said.

Tornadoes remain an awesome phenomenon, a reminder to Southerners and Midwesterners that spring has arrived and the weather is unsettled. But far fewer people die in tornadoes today because warning systems generally give people about 20 minutes to find shelter, according to Redmond.

Many of the tornado-related fatalities occur at night and to people who did not heed the warnings, Redmond said.

Still, he added, if you stood in the same spot in a Tornado Alley state such as Oklahoma, the chance you would be hit by a tornado are once in every 300 years.