Computers, Doppler radar makes predictions more accurate than 1980
By Robert Pore
The technology of forecasting severe weather events has greatly improved
since Grand Island was ravaged by seven tornadoes on June 3, 1980, said
Al Dutcher, state climatologist at the University of Nebraska.
Among the biggest improvements in the tools that allow forecasters to warn the public about severe weather are the increased speed and power of computers, along with the ability to store large amounts of data.
"When you look at where we were 25 years ago in terms of computing resources to where we are now, it's like comparing a horse-drawn plow to a modern monster tractor," Dutcher said.
Increasing speed and storage capacity of computers is important to weather forecasters, he said, because weather models are only as good as the amount of data that can be put into them.
"As your computing resources increase, you are able to put more data into them, and you can get a finer detail on your model," Dutcher said. "That makes it easier for us to have advance warning of major events as far as looking out not only for a few hours but several days ahead of a major outbreak."
The closer an event is, he said, the better the model is able to zoom in to provide more localized details.
Dutcher said increased computing power has made weather models -- including surface, mid-level and upper-level models -- much more sophisticated. Today's weather models can better tell forecasters if there are rotations involved with an approaching storm system.
"When you get more fine detail in your models, you are able to check some of these things," he said.
But in forecasting, Dutcher said, no model is perfect.
"You have several model choices to use, and really forecasting becomes a little bit of an art," he said. "Simply understanding biases in models -- such as if certain models are tracking either too far south or too far north, or too slow or too fast -- the longer you are in the business, the better you are at understanding local and regional biases."
Back in the 1980s, Dutcher said, meteorologists were pushing the envelope in forecasting the weather more than a week in advance.
"Now we are putting out information into a 14-week forecast, and we are also doing outlooks out into the future by 18 months," he said. "While the detail is pretty rough out into those longer distances, we have achieved something that we haven't been able to do in the past."
Along with the increased speed and memory of modern computers, another weather forecasting tool that has helped weather forecasters is the advent of Doppler radar systems.
"That has been a major advance for forecasting tornado activity in the short term," Dutcher said.
Doppler is the weather radar system that uses the Doppler shift of radio waves to detect air motion that can result in tornadoes. It can also measure the speed and direction of rain and ice, as well as detect the formation of tornadoes sooner than older radars.
"In a glorified term, it's what we call an echo effect," Dutcher said. "You shoot a pulse of energy out to an object, and you measure the return echo off of that. So, if you are shooting at a raindrop, you are basically measuring the intensity by how well it echoes back. That echo determines the density or the size of the drop.
"Therefore, you are not only able to measure with Doppler on a horizontal scale, but you are able to measure on a vertical scale. So you get closer to a three-dimensional impact on your thunderstorms."
If you have tornadic activity within a thunderstorm, he said, "everybody knows that a tornado is a circular type of a pattern. So with Doppler radar you can measure information that is coming toward your radar position and away from your radar position."
Dutcher said Doppler radar allows meteorologists to see areas within a thunderstorm winds that have rotation with them.
"You couldn't do that with the old radars back in the 1980s, where you had basically a horizontal picture," he said. "The common thing was to look at the flat picture of the thunderstorm and look for what we call hook echoes. That wouldn't tell you if a tornado was imminent but that it looked like a tornado. We got a lot of false forecasts on tornadic activity because basically the precision wasn't nearly as great as it is now."
Another difference is that there is a greater density of storm reporters out in the field nowadays than in the 1980s.
That human resource allows weather forecasters to back up the advances of Doppler radar with visual identification of storms better than ever in the past, Dutcher said.
And he said the next generation of weather radars will further improve the ability of forecasters to give timely warnings of pending weather dangers.
"We will probably see that over the next 10 years," he said. "They will replace the Doppler radars with a new generation of Doppler radars that will give us even greater detail on storm activity, and we will be better able to separate out such things as hail and winds within the systems themselves."
Along with more weather observers, warning systems are not only more sophisticated, but more people are able to access weather radio than in the past.
But as the art of weather forecasting becomes more and more sophisticated, Dutcher said the bottom line is still the ability of people to protect themselves and take seriously the warnings that a dangerous weather event is about to happen.
"What happened in Grand Island is not to say that we are not ever going to be totally immune to unfortunate loss of life due to tornadoes," he said. "At least the amount of information available to the public is more and more real-time, and there is more access to that data. But there is always going to be a portion of the public that won't take the threat seriously, unfortunately."