NORTHERN INDIANA — (EDITOR’S NOTE: This is the second in a four-part series on the National Weather Service, Northern Indiana)
“It’s a machine,” said Michael Lewis, warning coordination meteorologist at the National Weather Service, Northern Indiana, about the Doppler Radar. But the radar is just one tool in forecasting weather and what people see when checking radar images on phone apps, is not necessarily what is really happening.
“Our forecasting is really not critically dependent on the radar itself. It’s critically dependent upon the data we get in,” Lewis stated. This includes computer models.
“The radar itself is a mechanical device that has real distinct limitations. It’s an unbelievably powerful tool. The reality is it’s an unbelievable tool that allows us to provide warnings that we would not be able to otherwise. It has a lot of information and a lot of complex information to digest. It take a lot of training to interpret it well.”
Lewis explained the radar needs to be tilted. So the further away from the actual radar, the higher the radar reads above the ground. “By the time it gets midway across our warning area, your talking about thousands of feet off the ground. So the radar is not looking at what’s going on, on the ground. It’s looking above the ground,” Lewis stated. “The radar can give you indication of some type of circulation or intense storm, but it doesn’t mean that’s actually translated to the ground. We have no idea really what’s going on below the beam of the radar,” he added. This is where the meteorology training and computer models comes in.
According to Lewis the biggest challenge is everybody has access to the radar. “The radar itself has limitations people don’t really know about, unless they have been trained to interpret it,” he stated. So what people are seeing is what is in the atmosphere, but not necessarily on the ground.
Through training and experience, meteorologists anticipate where the storm is going. “If it’s cold enough the storm slows, the radar is slicing higher (in the atmosphere) and the storms are someplace else. You could get hit before the big red blob hits (seen on the radar screen). Our policy is anticipating where that storm is going and warn ahead of it, because we know if we’re looking at this in the radar and it slopes a certain way, we know its ahead of that line. So we warn ahead.”
“It’s a matter of trying to get people to understand the radar itself. By itself it is only a partial point of understanding. When you do meteorology, you have to look at all the pieces, all the parts. … If they have to use the radar, people are really encouraged to look at the warnings the weather service is putting out,” says Lewis.
Computerization and research of the radar has made significant changes. While the radar does a full atmosphere scan every five minutes, now if there is a big enough storm or critical storm, it begins scanning through multiple layers of the atmosphere generating reports every one to three minutes. “For us personally, that’s a great tool. We’re not waiting five minutes if a storm is moving 60 miles per hour, one mile a minute. … If I can go through and catch it, I’m catching it every minute, every mile.” This allows meteorologists to see how the storm is moving and if warnings need to be adjusted.
The new standard is to project a storm 15-30 minutes out. “This is about as effective as it can get. If you go beyond, too many things can happen in the environment,” says Lewis. This may mean having more warnings issued, but the warnings are smaller and shorter in duration and easier for people to understand and digest. Previously when warnings were issued for longer than 30-40 minutes, people would become complacent. They would learn of the warning but not hear the thunder or visually see the impending storm.
“Really in the last five years, it has become even more systematic and systemic change in the agency than the previous 15. It’s because people need to know, want to know and have to know …”