22 Aug Tornadoes put technology to work
Madison, Wis. – There is nothing that could have been done to avert the 26 tornadoes that swept through Wisconsin last Thursday. But thanks to technology, warning systems for such storms and aftermath clean-up efforts are vastly improved.
The 26 F3-grade tornadoes that swept through the south central and western parts of the state set a record for the number of tornadoes here in one day and, undoubtedly, took many people by surprise.
But thanks to a developing radar and information network, the region was not completely unprepared – weather services, insurance companies and emergency management teams were able to spot the warning signs and avoid heavy loss of life.
While technology can’t stop or divert such massive storms, it can get the word out and help pick up the pieces afterward.
Identifying the tornado
According to the latest statistics by the National Weather Service, the series of tornadoes went through Richland County and the communities of Stoughton and Viola, destroying 25 to 30 homes and damaging at least 200 more. One person – Harold Orlofske of Stoughton – was killed, and between 25 and 30 others were injured.
Edward Hopkins, assistant state climatologist and a lecturer at the University of Wisconsin-Madison’s Atmospheric & Oceanic Sciences department, said that tornadoes are created due to a combination of hot and cold air inside a cloud formation. That combination is sensitive to changes in wind speed, and a sudden change – known as a wind shear – can work the air into a rotation, creating a “rotating thunderstorm cell” known as a mesocyclone between 5,000 and 10,000 feet above the ground.
Once the mesocyclone comes into being, it becomes possible to detect the tornado with Weather Surveillance Radar-88 Doppler (WSR-88D), a radar system with a rotating antenna that sends out microwave signals. Those signals bounce off precipitation and return to the antenna, giving observers an updated picture of where the rain is moving.
“What is happening is that with the Doppler radar you’re not really seeing the tornado, you’re detecting the signature of the precipitation going away from one direction and coming toward another – the rotation of the cell,” Hopkins said.
A tornado is tougher to detect than a normal storm, however, since by the time it is within radar range it has already hit the ground and is doing damage. The curvature of the Earth means that the Doppler radar beams – which go out in a straight line – are often unable to “see” the lowest point of the ground until the tornado gets closer.
Weather satellites aren’t as useful for uncovering tornadoes according to Hopkins, since all the action is happening underneath the storm clouds and the tornado is aerially invisible. However, since some satellites work in the infrared and can analyze the temperature of clouds tops, it is possible to follow their path by identifying the coldest areas and seeing where they move.
“If you’re doing things with radar [and] you’re far away from the location, you don’t get to see the specific vortex itself,” Hopkins said. “Here you’re only looking at the possibility, watching the thunderstorm clouds as they become larger and checking their direction.”
Visual confirmation remains the best way to identify a tornado, however, and the National Weather Service maintains a strong network of forecasters who are stationed at various points in the state. Thanks to improvements in cell phone technology, those observers can communicate with each other and the home base when a mesocyclone is sited.
“It still boils down that you really need the human eyes to see there is a possibility of a tornado,” Hopkins said.
Computer models – fast but imperfect
Once the tornado is identified, computer algorithms can be useful for predicting its future path based on its current and previous path and other conditions. First-order stations and airports record temperature, humidity and wind speed of the storm and send it in to a main researcher, allowing mesoscale models to be updated almost instantly.
The technology does have its limitations, however, especially in areas like Wisconsin where tornadoes don’t happen very often and are not relatively strong. The tornadoes that happened last week were the most numerous since 1988, when the state had 24 in one day.
“For the most part, we get these pretty weak ones, which are hard to pick up at all. They’re weak and they usually touch down and are gone in very little time,” explained one forecaster with the National Weather Service. “To do an entire volume scan can take at least four minutes, so if it’s something that’s developed, touches down and goes back up, it might happen between your half-degree elevation slices that come in.”
The accuracy of the computer models can be affected by factors such as the boundaries of other wind fronts, differential heating or variations in moisture. Although the prediction models are usually accurate within an acceptable range, failure to pick on any of these variables can cause the predicted path of the tornado to vary slightly or even more significantly from the real thing.
While tornadoes are often too unpredictable for perfect forecasting, accuracy is the highest priority when picking up the pieces. After the storm has passed disaster response teams from insurance firms and state government head to the area, with the job of assessing the damages and supporting the storm’s victims.
Hopkins said that during this period field experts will be doing sight surveys, making sure that what each area had qualified as a tornado. They will do aerial and ground surveys to evaluate how fast the air was rotating, and from there evaluate how severe the damage was.
For companies such as American Family Insurance, the best tool for evaluate and repair the damages is a satellite-equipped RV connected directly into the insurance provider’s mainframe. Inside that RV, claims adjusters can look up the policies held in that region, directly take claims from residents and access television and Internet reports on the weather.
Ken Muth, media relations director for American Family Insurance, said that since the storm happened so close to the company’s corporate headquarters, the company established a temporary headquarters in Stoughton almost immediately. While it wasn’t able to make it to the site until Friday, using its software it was able to identify more than 100 claims held in that area and locate the most heavily damaged homes.
“This is a claim office on wheels,” Muth said. “We keep a close eye on what’s happening and if there is an opportunity to head out to an area, we do so.”