Dan Brown worked the morning shift Sept. 29, trying to read the future of a newborn tropical storm from atmospheric clues scattered through the Atlantic basin.
Wind shear tore at the lopsided system, whose thunderstorms clustered to the northeast, leaving a flank exposed and vulnerable to elements that fought to weaken its 70 mph winds. Although at least two forecasters are always on duty at the National Hurricane Center, it was his responsibility to write the 11 a.m. advisory.
“My (forecast) may live in infamy,” Brown said last week at the National Hurricane Conference in New Orleans during a session on the challenges of forecasting tropical cyclones.
On that Thursday morning, Brown predicted that the storm, named Matthew just the day before, would experience “only slight strengthening” during the next 24 hours.
“We all know that 36 hours later, Matthew was a Category 5 hurricane with 165 mph winds,” said Brown, a 24-year hurricane center veteran. “It was amazing, and frustrating.”
And it was testament that while hurricane-track forecasts have improved 50 percent over the past 15 years — the track cone will shrink again this season because of increased accuracy — predicting rapid escalation has lagged.
James Franklin, chief of the National Hurricane Center’s hurricane specialist unit, said there has been about a 20 percent improvement in the past 5 to 7 years on intensification forecasts and that humans are beating the computer models when it comes to intensity more often than not.
“There is a lot these guys see when they look at storm structure and what is going on in the environment that the models are not capable of seeing,” Franklin said. “We are finally making some progress in intensity.”
Still, 2015’s Hurricane Patricia in the Pacific Ocean underwent an extreme rapid intensification that wasn’t forecast by models or humans, deepening from 132 mph to 207 mph in 24 hours.
“The guidance early on in Patricia’s life just did not indicate the rate of strengthening that was observed,” Brown said.
This season, forecasters will have even more advanced tools to help better predict storm strength.
The new GOES-16 satellite, which launched from Cape Canaveral in March, is beaming back images four times the quality of what was previously available at five times the speed. It carries the Advanced Baseline Imager — a 16-channel camera built by the Melbourne-based Harris Corp. The older satellites have just five channels.
Also, while the previous satellites take 1,400 scans to capture the Western Hemisphere, the imager can do it in 21. During severe weather, forecasters can home in on particular storms and request scans every 30 seconds.
Michael Brennan, a senior hurricane specialist at the NHC, said GOES-16 will read temperatures inside the eye of a hurricane, finding the coldest ring of thunderstorm cloud tops, which can determine storm intensity.
Dry air and dust outbreaks, which are storm killers if ingested into a cyclone’s swirl, will be more easily monitored with the new satellite, and a revolutionary lightning mapper will deliver further research on the role lightning plays in intensifying hurricanes.
“We’ll be getting imagery more frequently,” Brennan said. “We don’t have to wait every 30 minutes. We’ll see it within five minutes.”
In Hurricane Matthew’s forecast postmortem, there is some thought that the wind shear fighting the storm was not as robust as it seemed. But even in a re-analysis that weakened the shear slightly, it still should have been strong enough to hold Matthew at bay.
“Matthew broke all the rules,” said Phil Klotzbach, a hurricane expert with Colorado State University. “It saw the shear and just didn’t care.”
Because Matthew’s extreme deepening happened in the middle of the Caribbean Sea, no one was affected by the unexpected acceleration.
But Brown worries that may not always be the case.
“If something like this happens near land, it will be a very bad situation,” he said. “Hopefully we are able to forecast those better in the future.”