A little after 7 P.M. on Thursday, Phil Badgett, a lead forecaster for the National Oceanic and Atmospheric Administration (NOAA), monitored Hurricane Florence from a field office in Raleigh, North Carolina’s inland capital. Depicted across his four computer screens by the region’s Doppler radar, the storm looked like a colossal sawblade, its green and yellow outer teeth just beginning to chew into the purple continent. “It’s beautiful and fascinating,” he told me, “but also horrifying. As the outer bands come in, what I’m watching for is tornadoes.”

Badgett, who is fifty-three, had a goatee and wore an engineer’s uniform of a quick-dry athletic shirt and sneakers. He recalled a severe storm that struck his family’s farm in Surry County, North Carolina, when he and his twin brother were about eight years old. “We jumped into bed with our parents, and my mom said to my dad, ‘I think we’ll have a tornado.’ My dad was like, ‘We don’t have tornadoes in North Carolina.’ Then we heard a sound like a jet-airplane engine.” They ran into the basement—just before the twister ripped up part of their house. “So I got interested in tornadoes to protect my family,” he said, “but then I just became fascinated with meteorology in general.” He went to North Carolina State, where the field office sits on the top floor of a science building. He started working there in March of 1990 and has never left.

Outside expansive windows, not a drop of rain had fallen yet, but trees tossed restlessly in the dark. Most of the campus was shut down owing to the approaching storm, but the field office bustled with seven other weather experts, each monitoring a different aspect of the storm. Three huge screens and around fifty computer monitors showed every map and metric of the hurricane, a digitized version of Florence swirling around them.

All of that information was pouring in from one of the world’s most impressive surveillance systems. NOAA’s polar satellites passed over the approaching storm twice a day, using microwave instruments to measure its cyclonic feedback loop. Data were also arriving from countless American weather balloons, buoys, wind gauges, and other sensors, as well as models from European and other weather agencies. For the previous four days, “hurricane hunter” WC-130J planes had been flying directly into the storm’s center, where the aircraft released cardboard-wrapped electronic sensors known as dropsondes that transmitted critical data three times a second as they plunged to the ocean. Scientists were then running this incoming torrent of intel through one of the most powerful supercomputers in the world, a custom-built, school-bus-size machine in a bland office building in Virginia, which processes three quadrillion calculations per second to produce models of what a storm like Florence will do next.

Every weather service in America—from TV-station predictions to commercial forecasts—is based on the data provided as a public service by NOAA. “I don’t think the general population realizes what we do, because we’re behind the scenes,” Badgett told me. “Everyone knows about Weather.com or AccuWeather.com, but no one knows about Weather.gov. But the irony is that they are drawing from our information.” He swiveled his chair to face the rest of the office and declared, “My co-workers really are unsung heroes.”

Just after 8 P.M., Scott Sharp, a nattily dressed lead forecaster in the Raleigh office, called the staff together for an update. He leaned back in an office chair; an untied lace dangled from his leather shoe. Earlier that day, the hurricane had been downgraded to a Category 2, but that just meant that its wind speed had decreased from approximately a hundred and forty to about a hundred and ten miles per hour, and did not address the destructive power of its rains. NOAA predicted that much of North Carolina would get well over twenty inches. “Fayetteville will have to do a major evac if it actually gets those kinds of rain numbers,” Sharp said. “We’re talking about historic levels.”

“People have made their decisions by now,” another meteorologist chimed in. “They’ve either left or they haven’t.”

Sharp ended the meeting by declaring, “This impact is going to be huge, but I can’t tell how bad.”

Badgett had just returned to his seat when the Storm Prediction Center in Oklahoma rang one of his colleagues, asking if they wanted to put a tornado-watch designation over their area, which encompassed about 3.5 million people. “We did have one funnel cloud reported over Sampson County,” Badgett said, “but that’s not enough. We’ll revisit the tornado threat tomorrow.”

Minutes later, a meteorologist shouted, “There’s a circulation over Wilson!” An incipient tornado was spinning near the eastern North Carolina town, the winds blowing toward the radar shaded green, while those blowing away were shaded red.

“Yeah, I see it!” Badgett replied. “Let’s put out a tornado warning until 9 P.M. in Wilson!”

Warnings went out over the Web and social media, as Sharp called officials in the city of Wilson. “This is the weather service in Raleigh, and we just issued a tornado warning to the southeast of Wilson heading toward Black Creek. Hello? Hello? Hello? Lost it.” He redialled. “Hey, this is Scott from the weather service in Raleigh. I was talking to a young lady and I got disconnected. . . .” Soon, cell-phone towers in the Wilson County area were triangulating every mobile phone in their range, and the area’s devices simultaneously let out a claxon beep as an emergency alert arrived. Finally, at 8:44 P.M., the tight swirl of red and green collapsed into a diffuse yellow cloud, and Badgett called the warning off.

As the dangerous edge of the hurricane swept past, and its softer side rotated into play, the meteorologists got a break. At the desk next to Badgett’s, Brandon Locklear, a tanned and muscular forty-one-year-old senior forecaster, who had also been inspired to study meteorology by witnessing the destructive power of a North Carolina tornado as a child, slugged a Coke as he neared the end of a twelve-hour shift. “You usually start to get to the burnout point in the nine- to ten-hour timeframe,” he said. “And we’ve been monitoring this thing twenty-four-seven for days.”

The office had the air of being under siege. Cookie packages, chip bags, and various cans of caffeinated drinks were stacked on a communal table. One man had brought a sleeping bag. Another weather specialist griped about only seeing her family once that week. “It’s not only the physical exhaustion wearing us down,” Locklear said, “but also worry.” He pointed at the basin straddling the border of the Carolinas on his computer screen, which was expected to endure the worst floods. “That’s where my parents are,” he said. “I’m not the only one with family being threatened. I’m just ready for this storm to be over, so we can see what the damage is and fix it.”

At 10 P.M., a huge computer monitor chimed as the National Hurricane Center, in Miami, Florida, beamed in. The staff of the Raleigh office assembled before a screen subdivided into the many video feeds of the various field offices on the conference call. The N.H.C. spokesperson said that data from the latest hurricane hunter flight had helped to reclassify Florence to a Category 1. Then the regional offices updated everyone on the situations in their areas. Last to speak was a man from the coastal field office in Morehead City, North Carolina, which was being pounded by a storm surge. Up and down the seaboard, field offices had set up cots and stockpiled food and water in back rooms. All hands remained on deck as they prepared to keep working for as long as they had power. “It’s looking pretty bad outside,” the man in Morehead City said, “but inside it’s like a summer camp. We’ve got thirty to forty people camped out!”

“Good luck to you guys,” the N.H.C. representative said, and signed off.

Not long after, a man with a buzz cut carried a clothes bag in. Locklear greeted him, “Hey, new blood.” After signing out, he passed a wooden plaque by the exit door inscribed with the agency’s directive: provide climatological information for the “protection of life and property.”

Locklear was back on duty the next day for the 4 P.M. N.H.C. conference call. Floodwaters were rising across the Carolinas, houses had been crushed by falling tree limbs, hundreds of people had been rescued, many more needed saving, and at least five people so far had been reported dead. Tens of thousands of other people, though, had heeded NOAA’s warnings and evacuated inland ahead of time. “For days, we’ve been saying this is a historic storm, and we’re glad we successfully got that message out to many people,” Locklear said. “But we’re just in the first quarter of the football game. We’ve still got a lot of work to do.”