Hurricane Gabrielle (1989) - Meteorological History

Meteorological History

A tropical wave moved off the coast of Africa on August 28 and entered into the Atlantic Ocean. Initially, the wave had moderate amounts of deep convection and was already well organized, which allowed it to quickly become a tropical cyclone. Based on ship reports, the wave was classified as Tropical Depression Ten beginning at 1200 UTC on August 30. Located 1,000 miles (1,609 km) southeast of Tropical Storm Felix, the depression tracked westward as a high pressure ridge formed between the two storms. Satellite imagery showed the depression developing a good outflow pattern. As a result, the National Hurricane Center upgraded the depression to Tropical Storm Gabrielle on August 31. It was noted that by as early as 1200 UTC later that day, Gabrielle was already rather large and well-defined. Gabrielle continued to move westward at 17 mph (27 km/h), and by early on September 1, the storm was upgraded to a hurricane. However, the storm was not operationally upgraded to a hurricane until late on September 2; Gabrielle was then located about 625 miles (1006 km) west of Cape Verde.

After becoming a hurricane on September 1, Gabrielle continued to intensify, but at a slower pace. By 1200 UTC on September 2, the storm strengthened into a Category 2 hurricane while centered about halfway between the Leeward Islands and Cape Verde. Early on the following day, Gabrielle became a major hurricane when it reached Category 3 intensity. Later on September 3, a ridge of high pressure formed a wedge between Gabrielle and Hurricane Felix. At 2046 UTC on September 3, a National Oceanic and Atmospheric Administration reconnaissance aircraft flight reported a pressure of 937 mbar (27.7 inHg), which was the lowest barometric pressure recorded in association with Gabrielle. It was later noted that the aircraft may not have entered the area with the most intense winds. Although barometric pressures slowly increased, Gabrielle continued to intensify, and by September 4, it became a Category 4 hurricane. Later that day, a trough extending from the Atlantic Canada southeastward to the Florida/Georgia border caused Gabrielle to recurve northwestward.

At 0000 UTC on September 5, Gabrielle reached its maximum sustained wind speed of 145 mph (230 km/h), though the barometric pressure was slightly higher than late on September 3. A hurricane hunter aircraft flown into the storm on September 5 reported that hurricane force winds extended 100 miles (161 km) from the center and tropical storm force winds 250 miles (402 km). At the time, Gabrielle was recurving west-northwest at 15 mph (24 km/h). Hours later, another recon flight into Gabrielle revealed that the barometric pressure was slowly rising and the eye began to expand which is sign that the storm was slowly weakening. However, forecasters were unsure if the weakening was temporary or definite, prompting one meteorologist to say that "Gabrielle may have reached its peak intensity, but its too early to tell", to explain the uncertainty of Gabrielle’s strength and if the storm will strengthen even further. The storm passed northeastward of the Leeward Islands and turned northward in response to a weakening in the ridge of high pressure caused by Hurricane Felix. Early on September 7, Gabrielle was downgraded to a Category 3 hurricane. Only six hours later, the storm further weakened to a Category 2 hurricane.

While a Category 2 hurricane, Gabrielle passed east of Bermuda early on September 8. Further weakening occurred and later that day, the storm was downgraded to a Category 1 hurricane. By early on September 9, Gabrielle began decelerating as it interacted with a frontal trough extending north to south across the western Atlantic Ocean, before becoming stationary about 475 miles (764 km) southeast of Cape Cod, Massachusetts on the following day. At 0600 UTC on September 10, Gabrielle weakened to a tropical storm. While being downgraded to a tropical storm, Gabrielle began drifting slowly westward in an area of weak steering well south of the jet stream. The storm later turned back eastward, ahead of an approaching cold front. On September 12, Gabrielle further weakened to a tropical depression, while being forced northeastward by a frontal trough. The depression lost most of its tropical characteristics, and by 1800 UTC on September 13, it merged with a storm system developing near Newfoundland on September 13.