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It started as a wobble in the African Easterly Jet, a river of air flowing across the continent of Africa from east to west just north of the equator between the scorching Sahara desert and the relatively cooler rainforests adjoining it. The disturbance created an area of unstable air, which allowed the formation of thunderstorms as the disturbance drifted westward across Cameroon and southern Nigeria. The persistence of the thunderstorms, fed by enormous amounts of evaporated water from the forests, eventually created a narrow trough of low pressure drifting off the coast into the Gulf of Guinea. A tropical wave was born.
Tropical waves often dissipate as they move over the slightly cooler environment of the Atlantic Ocean. Still, it was just past the autumnal equinox, with the sun almost directly overhead at noon, and the water was warm enough to sustain the thunderstorms within the system. It was being tracked and observed by this time, with computer models churning through terabytes of weather observational and simulation data, trying to forecast the risk of development. As the wave drifted west-northwest and away from the equator, it started drawing in air from its surroundings. But the system was large enough that Coriolis force began pulling the inflowing air to the right. Eventually, an equilibrium between the inward draw of the low pressure and the outward pull of the Coriolis force created a circular spin of the atmosphere. The weather satellites noted this change, and the wave was officially labeled Tropical Depression number 16, or TD16 for short.
The meteorologists at the National Hurricane Center, or NHC, in Miami, Florida, were very interested in the system by this time. They hoped that the moderate wind shear suppressing the deeper convective thunderstorms in TD16’s center would persist long enough for the system to hook on to a low-pressure trough crossing just north of its track and be pulled safely northward into the open Atlantic. It was not to be. The trough passed without connecting, and TD16 moved slowly out of the area of wind shear. The thunderstorms in its center were now free to build to great heights, the condensation of water vapor releasing vast amounts of heat trapped by the spinning air around the storm. A convergence and lifting of warm, moist air releasing energy into the closed circulation created a positive feedback loop, steadily decreasing the air pressure in the center and pushing the spinning winds above the threshold of thirty-nine miles per hour. When the satellite data revealed that the sustained winds had reached this next stage of cyclogenesis, system TD16 acquired a name; the tenth issued that season. Tropical Storm Jacob had arrived.
Jacob plodded steadily westward, carried along by the easterly trade winds like many Cape Verde storms. Unfortunately, this kept it above some of the warmest water in the world, and the storm hungrily fed on the energy released as the converging winds lifted the moist air aloft in its center. After two days over the warm water, with little wind shear or other environmental impediments, Jacob charged past the seventy-four miles per hour sustained wind threshold and became the season’s sixth hurricane.
The meteorologists at the NHC issued hurricane warnings for the Lesser Antilles Islands, Puerto Rico, and Hispaniola. The consensus of the myriad storm models was firm on this point: these islands would take a hit. From Hispaniola on, things got crazy—several forecast weather effects in play could send Jacob anywhere from straight west over Cuba, the Yucatan Peninsula, and the Gulf of Mexico to curving north into the Atlantic east of the Bahamas. Jacob continued to build, surging through Category 2 to reach Major Hurricane, Category 3 status a few hours before its first landfall on the island of Antigua. After battering that unfortunate land and the neighboring islands of Monserrat, Nevis, and St. Kitts, Jacob roared onward toward the Virgin Islands and Puerto Rico.
As Jacob penetrated the Caribbean basin, the meteorological picture became less uncertain. A turn to the north was now forecast—the average of the models predicted a path somewhere between Florida’s gulf coast and the Atlantic just east of the Bahamas. The cities in the dead-center of the prediction cone, from Miami to Jacksonville, began emergency preparations with the evacuation of people, aircraft, and ships. In the meantime, recovery vessels and personnel converged on the areas damaged in the storm’s wake.
The amount of energy powering a Category 3 hurricane almost defies belief. The largest explosion ever triggered by man released the energy equivalent to the detonation of fifty million tons of TNT—the condensation of water vapor rocketing upward in Jacob’s core released an equivalent amount of heat energy into the storm every hour. Jacob delivered the worst pummeling Puerto Rico had experienced since its direct hit by Hurricane Maria and then began skirting the northern coast of Hispaniola. Here, finally, Jacob faltered.
Free of the trade winds, Jacob slowed, allowing the mountains of the Dominican Republic and Haiti to disrupt the airflow into Jacob’s core. The storm lost some of its intensity and enough forward speed to “sense” a low-pressure trough coming off the Carolinas and begin a northward turn. Jacob’s eye passed between the Turks and Caicos and Great Inagua, then skirted the eastern islands of the Bahamas before curving north and east into the center of the Atlantic after another close brush with North Carolina’s Outer Banks. As it passed over the cooler waters north of the Bahamas, Jacob’s energy supply was cut off, and the storm rapidly de-intensified into an extratropical cyclone headed for Europe.
With dozens of deaths and billions’ of dollars worth of property damage, Jacob was a tragic disaster for the areas it touched in the Caribbean and the Bahamas. Yet, it could have been worse if the storm ranged up Florida’s east coast as a strong Category 3 storm. The citizens of Florida and the meteorologists of the NHC breathed a sigh of relief as people, aircraft, and ships returned from their exile. On the other hand, there was little sense of comfort for those caught in the storm’s path—only a fight for survival.
Dear God, be good to me;
The sea is so wide,
And my boat is so small.
Breton Fisherman’s Prayer
