On September 18, a vigorous tropical wave entered the tropical Atlantic ocean from the west African coastline. It tracked west-northwestward and steadily organized until it was designated Tropical Storm Humberto northeast of the Lesser Antilles on September 24. Despite some wind shear out of the west early on, Humberto steadily strengthened from formation. On the 25th, spiral bands and a central core appeared on satellite imagery. The storm became a hurricane the next morning. Meanwhile, the storm's forward speed slowed significantly due to weak steering currents.
Atmospheric conditions soon improved further over the storm. On September 26, Humberto rapidly intensified. An eye appeared and cleared out extremely quickly; within an 18 hour period, the storm went from a minimal hurricane to a strong category 4 hurricane. Overnight, an eyewall replacement cycle briefly halted strengthening, but the system rebounded surprisingly quickly. September 27 brought an even more symmetric eye surrounded by a larger ring of extremely cold cloud tops. This coincided with Humberto reaching its peak strength as a category 5 hurricane, with maximum sustained winds of 160 mph and a minimum central pressure of 924 mb. Humberto was the second category 5 hurricane of the season, after Hurricane Erin. This made 2025 the second consecutive year with multiple category 5 Atlantic hurricanes, due to the formation of Beryl and Milton in 2024. Such an event only occurred once before on record, during the 1932-1933 seasons.
During this episode of strengthening, Humberto's heading meandered a little, but the subtropical ridge generally pushed it west-northwestward at a slow but steady pace. Although conditions remained favorable a bit longer, another outer eyewall soon formed and disrupted the storm's internal structure, causing it to weaken back to a category 4 by the 28th. The core continued to evolve, but the storm remained a category 4 until the following evening, when shear increased markedly. This shear was associated with an approaching trough and in part due to the increasing proximity between Humberto and Imelda, which was approaching from the southwest. This shear destroyed the hurricane's core and exposed the center, leading to rapid weakening. By the afternoon of September 30, Humberto was down to category 1 strength, though it maintained an area of strong storms northeast of the center.
Meanwhile, the hurricane recurved toward the north and then sharply turned toward the east in the mid-latitue westerly flow. Humberto met a quick demise soon after: its circulation was absorbed into the approaching front during the morning of October 1.
The image above shows the impressive satellite signature of Humberto at its peak intensity as a category 5 hurricane on September 27.
Humberto did not affect any land areas as a tropical cyclone.
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