Windswept_ The Story of Wind and Weather - Marq de Villiers [72]
The U.S. center in its bunker and the Canadian one in its eyrie reflect the realities that they each face. Miami doesn't get hamme red every year but the chances that it will be are quite high. Dartmouth does suffer occasional hurricanes, and they can be more than usually unpredictable when they arrive. ("As hurricanes head north they become a different sort of beast," Chris Fogarty told me. "There is so much we still want to know.") Still, they are not common—the Maritime Provinces get a landfalling hurricane about every two or three years, and, if you include the region's maritime waters, one or two every year, but by the time they reach northern waters they are generally not much more than a moderate Category i. Juan, which rode a northbound jet stream directly from east of Bermuda, scooting so quickly up the ocean that the colder ocean temperatures had no chance to spin it down before it hit land, was a small and extraordinarily violent storm, and the day after it blew off across the gulf of St. Lawrence rumors asserted confidently that it had actually reached Category 3, but in fact it just made it to a 2.
Despite their differences, the operating centers of both institutions are quite similar—computer workstations where the forecasters pass their shifts, color-coded maps showing the current season's activity matched to past history, and, everywhere, photographs of what hurricanes have wrought, a constant reminder that the predictions they are forced to make can affect not just the livelihoods but in some cases also the lives of the people they serve, and the usual jumble of papers, clipboards, and old coffee cups. The maps are color coded in the same palette the NHC uses for its public advisories—green for tropical depression, yellow for tropical storm, red for hurricane, each active track fronted by a bulbous nose spreading out from the storm's current position, indicating the zone of uncertainty in guessing its probable direction. These seventy-two-hour track and intensity forecasts are issued four times a day for all storms in the North Atlantic and northeastern Pacific. They show predicted longitude and latitude, intensity (maximum sustained winds), and predicted path to a tenth of a degree.
By November of 2004, the end of the hurricane season in the Atlantic, the year's map showed nine red tracks. Most of them, because of a strong midseason ridge of high pressure, kept to a westerly bearing and, graphically and ominously, converged on Florida. Ivan, the storm I had been tracking, was shown clearly, but after it passed through Florida, it lost its red color, even on the Canadian map.
On one wall of the Miami center, a composite has been pasted, showing all the named storms from 1871 to 1998, a can of deadly worms writhing across the ocean, menacing in its general predictability (most of the storms went west, curved north, and then caught the prevailing southwesterlies) and even more so for the apparent randomness of each storm's path—some dived down into South America, others headed out to the mid-Atlantic, the occasional one even bullied its way to Baja California; they hit Texas, Louisiana, Mississippi, Florida, the Carolinas, Bermuda, New England, in a patternless wave of awesome destruction.
Sometimes the tracks even circle back on themselves, though this happens more commonly in the Pacific—to the east of Australia, where a regular procession of anticyclones arises every year, there were nine single cyclonic loops, four double loops, and one triple loop among ninety-three tracks, during a period of fourteen years. In the Atlantic, Hurricane Jeanne did a strange double backflip in 2004 and circled around twice before