Not that they're ones to brag about it, but hurricane forecasters have gotten a lot better at their jobs in recent years, especially when it comes to predicting where tropical cyclones will go.

From the period of 1990 through 2016, the three-day track error for tropical storms and hurricanes in the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico declined from 555km to 185km, dramatically reducing the size of hurricane warning and evacuation zone areas. Similarly, the three-day track error in the eastern North Pacific hurricane region fell from 415km to 135km over the same period.

These improvements are due to significantly better computer modeling, more powerful supercomputers, more advanced methods to collect and ingest data into these models (particularly from satellites), and improved techniques to blend these models into a single forecast.

Chaos theory

However, a new study suggests that this winning combination of computers and humans may be reaching its limits. "When you look at the improvements in hurricane track forecasting, they're astounding," said study co-author Chris Landsea, who is a scientist at the National Hurricane Center. "They've dropped two-thirds in a generation. But we know we’re not going to get to zero errors."

As first demonstrated by Edward Lorenz half a century ago with chaos theory, also known as the "butterfly effect," a very small change in initial conditions can produce substantial differences in future outcomes when it comes to meteorology. In other words, small initial errors in forecasts propagate down the line like a large snowball rolling down hill.

When Landsea and a forecaster at the hurricane center, John Cangialosi, looked at the data over the last five years, they noticed that these track improvements have slowed down. In fact, for five-day track forecasts over the last five years in the Atlantic, the trend is essentially flattening. Similar trends were observed in other areas around the planet where hurricanes form.

"Our hypothesis is that we’ve reached the limits of forecasting tracks, and in a decade we really will get to the point where we won’t get substantially better," Landsea said.

Other products

Not that forecasters will give up. Landsea said there is still room for improvement over the coming years, especially through developing better techniques for combining various computer models into a consensus forecast—so-called super ensemble forecasts. There will be continued improvement in computer modeling as well, with more sophisticated coding and higher resolutions to capture small-scale processes within storms. More and better data from satellites will help, too.

But for track forecasting, the low-hanging fruit has been picked. So the National Hurricane Center, the government office responsible for official watches and warnings, will continue to pivot toward improving predictions of intensity changes, which remains a big challenge. The hurricane center will also continue to extend its products beyond five-day to perhaps seven-day forecasts and develop probabilistic forecasting when it comes to impacts like storm surge.