Hurricane Sandy, even with its left turn heard ’round the world, was well-forecasted by the National Hurricane Center.
But even with the accurate track forecast, the storm’s “cone of uncertainty,” the estimated track of the eye of the storm, had a range of 121 nautical miles, meaning it could have hit anywhere between Stamford, Connecticut, and Fredricksburg, Virginia.
As it turned out, the storm’s eye made landfall on Brigantine.
The National Hurricane Center has tracked the intensity and location of storms since 1970 and noted errors in forecasts.
And overall, there have been improvements in both the tracking and measuring of intensity of storms since then, although intensity forecasting lags the improvements in track forecasting.
Since 1970, the so-called “cone of uncertainty” has shrunk, from 253.8 nautical miles then to 121 nautical miles in 2012. Now, the cone is 103 miles. These distances reflect the cone at three days before landfall. An earlier, larger, five-day cone is also standard.
“The computer models that we have continue to be better and better. As more observations and data go into the models, we are able to better understand how a storm will move,” said meteorologist Michael Brennan, now the acting chief of the NHC’s Hurricane Specialist Unit.
As part of the Hurricane Specialist Unit, Brennan leads the team responsible for issuing the watches and warnings for tropical systems in the North Atlantic Basin, which includes the United States. They also provide the “big-picture forecast” for other countries, including those in the Caribbean.
When it is not hurricane season, an offseason defined as Dec. 1 to May 31, Brennan and his department conduct weeklong trainings for the emergency management community and the National Weather Service.
Brennan was also the meteorologist who made the call to include New Jersey in Sandy’s cone.
“You do not forget those types of forecasts,” he said of that moment.
Brennan said intensity forecasting will always be more difficult than the track forecast.
“In the track forecast, if you have the large-scale pattern correct, then the track will be OK. However, you have to go down to the eye and eyewall level to have a good gauge on the intensity. With most hurricanes far away from land, you do not have a great initial analysis of the storm.”
In addition, how a system interacts with the ocean and sea surface temperatures in the open water are critical to the strength of the system. The problem? That is where we have the least amount of observations.
But on top of that, societal factors are at play.
“The (intensity) forecasts are improving slowly, but the demands from society are growing even faster. Storm-surge evacuation and those decisions grow more critical as the population along the coasts continue to increase,” Brennan said.
More improvements are on the way, he said.
This year, the new GOES-16 satellite will be operational. The weather community already is in awe of the majestic pictures it has produced, with its five-minute imagery and ability to obtain one-minute images in special circumstances, providing more details about the strength and characteristics of a storm.
So what can we expect the next time a Sandy-style storm makes its way to New Jersey? With more data, pinpointing who should be worried most about storm surge and flooding will allow emergency management officials to make more informed decisions about who should leave and when.