Meteorologists have spent decades drastically improving predictions on where a looming hurricane could hit — warnings that potentially drive millions of people from their homes. Now, they aim to determine better how powerful those storms actually will be.
Forecasters are debuting their new hurricane weather research and forecasting model next month, which, for the first time, will take into account most data from within the storm and use it in real time to determine its strength better.
”The processes at the inner core are not well informed and not well predicted,” senior hurricane specialist Richard Pasch said at the National Hurricane Centre. ”With the [new model], we’re hoping that we can analyse that middle core.”
Until now, experts have mostly relied on the Geophysical Fluid Dynamics Laboratory model, which, like those before it, mainly depended on initial storm information paired with historical data for similar storms. The higher-resolution new model will consider conditions over the oceans that have never been plugged into models before.
It could take years, and some tinkering, for the new model to realise its full potential. But forecasters hope the result will be a greater understanding of storms such as hurricanes Charley and Wilma, which grew substantially stronger in a matter of hours.
Wilma went from being a tropical storm to the strongest Atlantic hurricane on record in a day.
Better predictions
The hope is that the model will better predict the strength of a hurricane when it eventually makes landfall and ultimately save lives.
The National Hurricane Centre has cut its average forecast error on storm tracks in half over the past 15 years. Average track errors last year were about 88,5km on one-day forecasts, about 178km on two-day predictions and 270km on three days’ ahead.
In the same period, two-day forecasts for the intensity of all tropical cyclones improved from an average of about 29km/h to about 27km/h.
”We’ve made those improvements in track, but we’ve made little improvement in forecasting intensity,” Pasch said. ”It was what the science allows. We understand more about hurricane track than intensity.”
With the new model, that should change. Information from hurricane-hunter aircraft, satellites and other sources will immediately relay wind conditions in and around the storm, temperature, pressure, humidity and other oceanic and atmospheric conditions and analyse them to determine the track and intensity.
Real time
Naomi Surgi, who coordinates the hurricane-modelling programme at the National Centre for Climate Prediction in Camp Springs, Maryland, said using real-time data provides the most accurate forecasts.
”You have to with as much accuracy as possible describe what that hurricane is doing now,” she said, adding the new model shows great promise. ”It’s getting the storm right, it’s getting the ocean underneath the storm right, it’s getting the environment around the storm right.”
The model has been in development since 2001. Surgi said while improvements will begin the day after it goes operational next month, the model is expected to be used for the next 10 to 15 years.
Forecasters will also test a new radar technique that allows meteorologists to determine wind speeds and barometric pressures in all parts of a storm every few minutes, not the several hours it takes to get readings from hurricane-hunter aircraft, said Colin McAdie, a hurricane-centre meteorologist.
The National Centre for Atmospheric Research’s method of analysing radar images gives a three-dimensional view of hurricanes that are within 193km of land and will warn if storms are strengthening or weakening unexpectedly, he said.
Even with the expected improvements the new model could bring, Surgi said meteorologists still concede they will never deliver error-free hurricane forecasts.
”We have stopped thinking in terms of 100% accuracy,” she said, ”because I don’t think it will ever be realistic to expect that.” — Sapa-AP
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