Posted on Sun, Apr. 05, 2009

A tornado fact your favorite forecaster probably doesn't have: June 10 is a day to watch out for in Kansas. Over the past half-century, at least one tornado has touched down in the state 22 times on that date -- six more times than any other day. A total of 53 tornadoes have touched down on June 10 since 1950. You might also keep your eye on May 4 and May 5 -- the only dates that have recorded more than 80 tornado touch-downs since 1950.

And one statistic you probably don't hear much: In a typical year, the annual tornado death toll in Kansas is zero.

The figures come from the National Climatic Data Center's Storm Events Database, which started tracking tornadoes in 1950 and was later expanded to include all significant weather events.

The database provides a unique perspective on Kansas weather.

Winter storms, the figures show, kill more Kansans than tornadoes do. And hailstorms cause close to as much property damage.

But when all factors are considered, Kansas' section in the Storm Events Database is dominated by tornadoes -- particularly by a handful of monster tornadoes, including the one that leveled Greensburg on May 4, 2007.

Andy Kleinsasser, a meteorologist who monitors severe storms for Wichita's National Weather Service office, said most of the 3,605 "tornado events" that occurred in Kansas from 1950 through 2007 were relatively minor.

"Typically, 75 percent of all tornadoes are tiny little ones," he said. "The typical diameter on those is less than 100 yards. With a 100-yard column, there's a pretty low chance it will hit a population area."

Kleinsasser noted that the storm database counts "tornado events" rather than actual tornadoes. A tornado that crosses three counties is considered to be three events in the database.

A storm the size of the Greensburg tornado usually has several entries.

"The Greensburg tornado was about as big as it gets," Kleinsasser said. "It was more than a mile and a half wide. We've only had a handful of those over the last 50 years. It's just very rare."

Database history

The Storm Events Database started tracking tornadoes in 1950, and meteorologists began adding hail and thunderstorm data five years later. By 1993, forecasters were tracking flooding, ice storms, heavy snowfalls and other extreme weather events.

In recent years, forecasters have included narratives of many events.

The numbers show that Kansas ranks second to Texas in the number of tornado events since 1950, but 10th in the number of fatalities.

Among Kansas counties, Sedgwick County's 74 tornadoes ranks second only to Sherman County's 85 in the number of reported tornadoes.

In terms of fatalities, Butler County's 28 deaths ranks second only to Cowley County, which is where the May 25, 1955, Udall tornado killed 77 people.

The database shows that tornadoes have touched down in Kansas in every month, thanks to 2006. A Jan. 28, 2006, storm system produced two small tornadoes in northern Kansas and spawned a landspout tornado near Newton that shattered windows on at least 100 cars at an auto dealership.

Each tornado in the database includes a Fujita Scale ranking of 0 to 5, with 5 being the most destructive and having winds of up to 318 mph, enough to tear a house off its foundation and carry it away. In February 2007, forecasters adopted the Enhanced Fujita Scale, which modified the way tornadoes are rated but continued to rank them on a 0 to 5 scale.

Since 1950, there have been only six F5 tornadoes in Kansas, the latest being the EF-5 storm in Greensburg. Because such storms typically cross county lines, there are more than six F5 entries in the storm events database.

A summary:

• F5: 17 events that caused 133 deaths, 1,102 injuries and $1.15 billion in property damage

• F4, winds up to 260 mph: 59 events that caused 49 deaths, 725 injuries and $409 million in property damage

• F3, winds up to 206 mph: 197 events that caused 20 deaths, 508 injuries and $671 million in property damage

• F2, winds up to 157 mph: 456 events that caused four deaths, 262 injuries and $260 million in property damage

• F1, winds up to 112 mph: 821 events that caused 20 deaths, 95 injuries and $95 million in property damage. Most of those deaths occurred on June 17, 1978, when a tornado capsized the Whippoorwill showboat on Lake Pomona in Osage County, drowning 16 of its 58 passengers.

• F0 winds up to 72 mph: 1,636 events that caused one death, three injuries and $15 million in property damage. The death occurred in Barton County in 1955, but the database contains no details.

Tracking the storms

At the National Weather Service office, Kleinsasser looks for trends in the tornado data.

He said 1990 and 1991 were active years for tornadoes in Kansas. He said 2007 and 2008 showed a similar pattern.

But after scouring the data for unusual winter weather patterns and unseasonable atmospheric conditions, he's been unable to find a link.

"We're just not finding much of a correlation," he said.

Although tornado research has improved over the years, Kleinsasser said, predictions about the severity of an upcoming tornado season are about as accurate as predictions about the severity of an upcoming winter.

"It's about as good as flipping a coin right now," he said.

Forecaster Brad Ketcham helps enter the local storm data into the national database each month. Sometimes it's a judgment call, he said, about which storms make the database.

In December, after the season's first winter storm produced little snow in Wichita but lots of traffic accidents, forecasters decided to add it to the database.

"Granted it was only inch or two, but it caused 400 or 500 crashes," Ketcham said. "Sometimes it's a judgment call whether it gets reported."

Ketcham said there's no discretion when it comes to reporting tornadoes.

"All tornadoes are put in there, no matter what," he said. "Even if it's a weak tornado, it has to be reported."

For a tornado to be confirmed, he said, it requires an eyewitness account or a confirmation of damage.

That means Ketcham, Kleinsasser and their fellow forecasters often go into the field to determine whether storm damage was caused by a tornado.

"If everything is laying down in the same direction, typically we're looking at straight line winds," Kleinsasser said. "Tornado damage is going to be a little more chaotic."

Kleinsasser said a growing network of trained tornado spotters and growing numbers of ordinary people willing to share digital tornado pictures often make it unnecessary for forecasters to confirm that a tornado has hit.

"It's really hard nowadays to have a tornado that's not reported," he said.

Reach Hurst Laviana at 316-268-6499 or hlaviana@wichitaeagle.com.