Instead, they accumulate

From Into the Raging Sea by Rachel Slade. Page 21.

The storm would move a little farther southwest, BVS told Davidson, then cut north toward South Carolina. El Faro could easily skirt below the system, as long as she kept up her speed. The captain clicked the forward arrow and saw the future: tomorrow, the ship would be halfway to San Juan and Joaquin would be nearing the US coast. As he clicked forward in time, El Faro moved along its expected route, and Joaquin inched farther and farther north, away from the islands. They’d be fine.

What Davidson didn’t know was that due to a clerical error, the 5 a.m. BVS forecast he’d downloaded that morning was identical to the one sent six hours prior. Because BVS took several hours to process NHC data before issuing a report, that error meant the weather forecast Davidson was looking at was based on raw data nearly eighteen hours old. The report depicted Joaquin as a north bound tropical storm when, in fact, by dawn on September 30, most forecasters, including the NHC, recognized the system as a slow-moving, full-blown Category 3 hurricane that might not budge from its southwesterly track.

According to Davidson’s BVS report, they’d see some weather—winds and waves, maybe twelve to fifteen feet—the aftershocks of the storm. He sent the update to the computer terminal on the bridge for the other officers to see. “This doesn’t look too bad,” Shultz said, examining the projection when the captain joined him. “The ship can handle it.”

“We’ll see what the schedule looks like,” Davidson said, clicking through to Friday. He took the opportunity to lecture his new chief mate on the finer points of routing a ship. “Joaquin’s gone a little south,” he said. “This is why you watch the weather all the time. All the time.” He cleared his throat then added, “Absolutely.”

This happens time and again in this story. An error slips in and goes unnoticed, in this instance a failure by BVS to update and a failure by Davidson to notice it hadn't updated. Had there only been one unnoticed error, the tragedy would have been averted. Instead they accumulate.