Long before Florence started grinding its way across the Carolinas, weather satellites were peering down from space to capture detailed images of the storm — now downgraded from hurricane to tropical-storm status — and to help meteorologists track its path and intensity.

Weather satellites are operated by the U.S. and several other nations. But many of the Florence photos are coming from the Geostationary Operational Environmental Satellite-16, or GOES-16, an American satellite that, since 2016, has been gazing down at the planet's surface from its geosynchronous orbit some 22,000 miles above the equator. (Geosynchronous means it matches Earth's orbit.)

The satellites have transformed the way weather watchers and government officials track potentially deadly storms.

Before satellites, there was no way to track a storm like Florence, said Chris Knowlton, assistant director of the Inner Space Center at the University of Rhode Island. When a powerful hurricane struck Galveston, Texas, in 1900, it became the deadliest natural disaster in American history, killing roughly 8,000 people "because they didn’t know it was coming,” Knowlton said.

Thanks in part to satellite data, meteorologists were able to issue detailed warnings about Florence days before it made landfall — and to predict with uncanny accuracy just where landfall would occur.

“It’s one of the greatest tools we have today,” Knowlton said of satellite data. “We can say that they’re coming, where they’re going to make landfall, where people should evacuate.”

NOAA's DSCOVR satellite captured this view of Hurricane Florence, Hurricane Helene, Tropical Storm Isaac and Subtropical Storm Joyce NOAA

Weather satellites captured data about Florence while it was still far out in the Atlantic Ocean, before land-based weather radar could track it or specialized “Hurricane Hunter” airplanes operated by the National Oceanic and Atmospheric Administration (NOAA) could reach it, said Joel Cline, a meteorologist with the National Hurricane Center.

“They’re an immense help over the open ocean. That’s how we knew this storm came off Africa, Cline said, adding, “Out there where you don’t have Hunters, you’re telling ships to leave for their safety.”

Knowlton said GOES-16, which is operated by NASA and NOAA, has “amazing capabilities.” It has far greater image resolution than the previous generation of satellites, he said, and it can better determine how storms form. The most important advance is the speed at which the satellite can take pictures. Knowlton said GOES-16 can capture images three times faster than its predecessor, GOES-14.

"Having five minutes between pictures instead of [15] is huge," he said. "You can see it developing features. You can see the eyewall expanding or getting smaller."

Weather satellites take pictures in daylight and, with the help of infrared cameras, at night. They gather information about a hurricane’s structure and wind speeds and help gauge the threat of flash floods when a storm hits land. The satellites can also measure the humidity around a storm and even the temperature of ocean waters. “The ocean is the heat source that drives the engine of the hurricane,” Knowlton said.

Florence, which made landfall in North Carolina early Friday morning, has caused severe flooding and widespread power outages and has been blamed for at least six deaths.

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