Severe Weather Season Part 1: Understanding the Storms
An outlook for the upcoming severe weather season and how to understand the timing and development of storms
Posted on Mar. 27th, 2014
K-State Research and Extension
MANHATTAN, Kan. – Fifty-six tornadoes were reported in Kansas last year, which made it the quietest year for tornadoes since 1994. According to the National Weather Service, only five of the tornadoes ranked as strong, violent tornadoes. There was one injury and no deaths.
The average number of tornadoes in Kansas, based on data from the past 30 years, is about 80 annually, said Chad Omitt, warning coordination meteorologist with the National Weather Service Office in Topeka.
Last year was a relatively quiet year in Kansas, because the pattern of the storm systems was set up to the east, said Mary Knapp, climatologist for Kansas State University. Although tornadoes can happen and have happened every month of the year in Kansas, May is historically the month with the most tornadoes.
“The expectation is as we move toward more normal rainfall patterns in April and May, we see an increase in severe weather outbreaks,” Knapp said. “People should remember that it only takes one tornado to be devastating. Low numbers are no consolation when one creates havoc.”
How severe weather develops
A sharp contrast in the air masses, Knapp said, causes severe weather—thunderstorms and tornadoes. The contrast can be in temperature or in the amount of moisture, particularly if there is a dry line of air behind the storm system.
“Any of those imbalances can fuel the severe weather,” she said. “If thunderstorms are large enough that they intersect with the jet stream, that puts the final ingredient in the mix and starts a rotation that can produce the severe events.”
No area of Kansas is more susceptible to tornadoes than another, Knapp said, but people tend to hear more about the damages caused by tornadoes in the eastern part of the state due to the greater population density.
“The amount of damages that might occur in the western areas, including damages to fence rows and irrigation systems, tends to be underreported,” she said. “When you talk about fence rows that might have taken 20 to 30 years to be developed to protect against erosion, and have been wiped out within a couple of hours, it can be a very devastating to the area economy.”
Although tornadoes can arrive at any time of the day, the most common times in Kansas are early afternoon to mid-evening, Knapp said.
“It tends to be earlier in the western part of the state and later in the eastern part of the state, but it can vary widely depending upon how the storm actually develops and progresses across the country,” she said.“You don’t want to assume that it will be at a certain time.”
Knapp said when there is a severe thunderstorm watch or warning, people should treat it with caution, as severe thunderstorms could produce a tornado with little or no warning. Even without a tornado, large hail, heavy rains that might produce flooding and damaging straight-line winds are possible.
Watch versus warning
In the event of a tornado or severe thunderstorm, Omitt said, people should know the difference between a watch and a warning.
“A watch is usually large in space, a large part of a state or many different states, and it runs on the order of four to eight hours,” he said. “It’s basically a heads up. Nothing could be happening right now, but in the next several hours thunderstorms could develop, and the atmosphere could produce tornadoes.”
Omitt said a change in behavior is required when a watch is issued. People should consider staying in a safe place, rather than being outside, in a vehicle or in any situation of vulnerability. People should also consider reviewing their safety plan during a watch in case a warning commences.
“A warning is when something is either on the ground or there’s a good chance that in the next half hour a tornado might develop in that warning area,” he said. “That’s when you put your plan into action and protect yourself and your family.”
Sometimes when a warning is issued, Omitt said, people want to look outside and confirm the potentially dangerous situation for themselves. Worse yet is the situation where people go after the tornadoes to take photos and document them. It is important to seek shelter immediately in a warning.
“I worry that perhaps we’re creating an environment where it becomes something that people want to do, forget the risk they are taking and forget the danger involved with these storms, not only the tornadoes but the lightning and large hail that those can bring,” he said.
The El Reno, Okla. tornado last May near Oklahoma City is an example of the dangers associated with going out in a vehicle and getting too close to a tornado.
“Specifically, these were people who were trying to chase the tornado, document it, take pictures,” Omitt said. “They got too close to it. In fact, all of the fatalities in that event were people in automobiles who got too close to the tornado. I think that can be a cautionary tale.”
Knapp advises people to never leave shelter during a severe weather event and wait for an “all-clear” report before going outside. Also, have multiple ways to receive weather reports in case one method of communication isn’t working.
“In many cases, the tornado won’t be that clean, visible funnel we’re accustomed to seeing on television,” she said. “It can be wrapped in rain and difficult to see that it’s actually a tornado. If you’re seeing a heavy rain shaft down the road, it might be best to delay your trip and wait it out in a safe place.”
Don’t underestimate lightning during severe thunderstorms, either, Omitt said. Lightning is so common that many people don’t think of it as a threat.
“If you’re close enough to hear thunder, you’re close enough to be at risk,” he said. “We always emphasize to people that if you can hear thunder and you’re outside, just go to your vehicle, roll up the windows and keep your hands inside until the storm passes.”