Hurricane Humberto was the eighth named storm and fourth hurricane of the 2001 Atlantic hurricane season. Humberto formed on September 21 well to the east of the Bahamas from a low-pressure area spawned by Hurricane Gabrielle. Humberto moved northwest, north, then northeast, peaking at 105 mph with a pressure of 970 mb. It dissipated on September 27.
Humberto caused no damage and no deaths.
|Formation||September 21, 2001|
|Dissipation||September 27, 2001|
|Highest winds||105 mph|
|Lowest pressure||970 mbar|
A trough of low pressure extended southwestward from the circulation of Hurricane Gabrielle. On September 18, a westward moving upper-level low passed over the surface of the trough about 600 miles south-southeast of Bermuda. Because of the passage of the upper-level low, convection was enhanced in the area. A weak low formed within this area the following day and it began to drift off to the west. The low gradually became better organized, and Dvorak classifications were initiated early on September 20. At 1200 UTC on September 21, the low became Tropical Depression Ten when deep convection developed near the center of a broad cyclonic circulation defined by low-cloud vectors in satellite imagery. When the depression formed, it was located about 425 miles south of Bermuda. After forming, the depression moved to the northwest, and the circulation remained weak and disorganized on September 21 despite a rapidly improving appearance in satellite imagery. The next day, however, the surface development appeared to catch up to the satellite signature and by 1200 UTC on September 22, it is estimated that the depression became Tropical Storm Humberto, about 275 miles south-southwest of Bermuda. Humberto moved north-northwest as it moved along the periphery of the subtropical ridge. It gradually strengthened during this time as well, becoming a hurricane at around 1200 UTC on September 23, while located about 150 miles south-southwest of Bermuda. Humberto turned north-northeast and reached its first peak intensity of 100 mph and 983 mb at 0000 UTC on September 24.
Strong upper-level westerly wind shear began to disrupt Humberto's organization, and within 12 hours, Humberto's winds had decreased to 80 mph. However, once Humberto passed north of the subtropical ridge, it turned northeast and accelerated within a more vertically uniform steering current. At this time, the weakening trend slowed. With a large mid- to upper-level cutoff low over the Midwestern states, downstream ridging caused Humberto to slow on 25 September. An eye became apparent intermittently on satellite imagery during this time, as well. Humberto moved beneath the downstream ridge and turned northward briefly the next day. At this point, Humberto's eye became much better-defined, and it quickly strengthened over waters no more than 25-26°C, reaching its peak intensity of 105 mph and 970 mb at 1200 UTC on September 26, while located about 175 miles south-southeast of Sable Island. The ridging that had been sheltering Humberto quickly collapsed and upper-level westerly flow again impinged on the cyclone. Humberto moved northeast and began to accelerate over cooler waters, weakening rapidly as it did so. Moving eastward at a swift foward speed of 28 kt, Humberto weakened to a tropical storm at 1200 UTC on September 27, while located about 350 miles southeast of Cape Race, Newfoundland.
As Humberto was becoming extratropical, its cloud patter became distorted and separated from the low-level circulation center, and Humberto dissipated when its circulation degenerated into an open trough shortly after 1800 UTC on September 27.