(Bloomberg) -- Hurricane Helene is forecast to pummel Florida’s west coast Thursday with devastating winds — but exactly how devastating won’t be evident until skies clear.
That’s because wind speed predictions are hamstrung by patchy data and gaps in research about how hurricanes gather power from warm waters in the hours before they reach land. While forecasts tracking where storms will strike have become much more accurate since the mid-1990s, methods for pinpointing their intensity have lagged behind, despite recent improvements.
Inside a hurricane, “we don’t really know what processes are going on and that makes it hard to simulate in the computer model,” said Falko Judt, a research meteorologist at the National Center for Atmospheric Research in Boulder, Colorado. “We need actual measurements from right at this moment and we don’t have them. So what goes in the model is best estimates.”
Errors in wind-speed forecasts have deadly consequences, influencing whether people in a storm’s path decide to stay or flee — and a phenomenon known as rapid intensification is raising the stakes even more. As climate change fuels hotter ocean temperatures, cyclones are getting stronger, faster. Helene is one example: It grew from a weak tropical storm to a hurricane in just 24 hours.
Defined as a 35 mile-per-hour (56 kph) increase in a cyclone’s top winds in the span of a day, rapid intensification can turn a storm into a major threat in a matter of hours, taking emergency personnel, political leaders and residents by surprise.
This week, Tropical Storm John quickly intensified into a Category 3 hurricane on the five-step Saffir-Simpson scale before slamming the western coast of Mexico, killing at least two people. But perhaps the starkest example in recent years is Hurricane Otis, which rocketed from a tropical storm to a Category 5 hurricane in the day before it struck Acapulco last October. Otis killed at least 52 people and caused about $16 billion in damages and losses.
Research shows scientists have finally started making progress toward reducing errors in intensity predictions, thanks to better modeling techniques and new data collected from storms over the open ocean, according to Lisa Bucci, a hurricane specialist at the US National Hurricane Center in Miami.
But for now, when federal meteorologists hold training sessions for emergency managers, they include a warning not to take storm wind predictions at face value, she said.
If an outlook calls for a Category 1 hurricane, Bucci said, “we’ll say that we want you to prepare for a category above that because of the errors associated with our forecasts.”
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