Katrina was the deadliest hurricane to hit the US in a century.

On the morning of 29 August 2005, it lashed New Orleans with near-200 kilometre per hour winds that drove a storm surge up to eight metres high and flooded 80% of the city. Across the region at least 1,200 people died.

Hurricanes are notoriously unpredictable. But science is catching up, and helping to save lives. Ten years after Katrina, a sophisticated meteorological forecast gave the people of southwest Mexico five days to prepare for Patricia. When the most powerful hurricane in North America’s history struck, only two people were killed by the storm.

Credit: DAVID J. PHILLIP / AFP / Getty Images

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Patricia appears

A Terra satellite captured this ominous image of Patricia on 23 October, 2015, just hours before the hurricane made landfall. But satellite images from almost a week earlier had foreshadowed what was in store.

As the storm developed, Hurricane Hunter aircraft flew in for a closer look, dropping devices called dropsondes to measure the interior barometric pressure and wind speed.

All those data were relayed to supercomputers. Season after season, the more data we feed them, the better their predictive power. In 2005, they could predict a hurricane’s track to within a range of some 250 kilometres three days in advance. Today they can track them to that level of accuracy five days in advance.

Credit: Jeff Schmaltz / LANCE / EOSDIS Rapid Response / NASA Earth Observatory map

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Highs and Lows

A hurricane’s strength is far more unpredictable than its path.

Patricia displayed one of the fastest storm intensifications in history.

Early in the morning of 22 October, her maximum sustained wind speed was 120 kilometres per hour. Just 24 hours later, she clocked 320 kilometres per hour.

Shortly afterward, NASA’s Suomi NPP satellite passed over the angry storm and captured this infrared image that represents the temperature of the tops of the clouds. The more powerful a storm, the higher the clouds climb and the colder their tops become. Patricia’s cloud top temperatures had plummeted to -90 °C, indicating a vast cloud structure that was likely to produce torrential rain.

Credit: NASA / UW / CIMSS / William Straka III

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Installed on the International Space Station in 2014, the ISS-RapidScat Instrument can see right through a storm. By bouncing microwaves off the ocean surface, it uses the echo strength to measure ocean surface roughness and calculate wind speed and direction. In this 23 October 2015 image (lighter colour represents faster winds), Patricia’s surface wind speeds exceeded 110 kilometres per hour.

Credit: Joshua Stevens, using RapidScat data from the Jet Propulsion Laboratory

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Less than 24 hours later, Patricia made landfall. Luckily, the hurricane weakened even faster than it had intensified, dropping to Category 3 status just before touching the shoreline. Even so, the damage was severe (above). But the long-range forecasting gave people time to get out of harm’s way.

Credit: MARIO VAZQUEZ / AFP / Getty Images