Around October 1, a tropical wave entered the Caribbean. Associated thunderstorms were vigorous, but unorganized, and the disturbance continued west-northwestward. Within a few days, a low pressure center developed in association with the wave and it steadily consolidated. Late on October 4, Tropical Depression Twenty-Six was designated a little south of Jamaica. The depression was entering the western Caribbean, where it found nearly ideal conditions for development: the highest oceanic heat content in the Atlantic basin, low shear, and high humidity. It became Tropical Storm Delta, the 25th named storm of 2020, on October 5. This handily beat Gamma of 2005, the 25th storm of that season, which was named on November 15 of that year (a storm identified in post-season analysis in 2005 accounts for the 25th being Gamma, not Delta). It was also the second time the Delta named was used, after 2005.
Vigorous convection wrapped around the cyclone's center soon after it was named and rapid strengthening began; even a few dry slots did not slow it down for long. Delta became a hurricane that very evening. The cyclone was very compact, with a small central dense overcast. Quick deepening continued on October 6: the storm incredibly became a category 4 by midday, reaching its peak intensity of 145 mph winds and a pressure of 956 mb. The core was so compact that no eye was apparent on visible satellite imagery; nevertheless, analysis indicated there was a pinhole eye, only a few miles in diameter. Meanwhile, Delta sped up a bit toward the west-northwest.
The cyclone continued to exhibit curious behavior the next morning: convection was extraordinarily deep near the center, but the eyewall appeared to collapse, weakening the storm. As a result, Delta lost some steam before making landfall in the Yucatan Peninsula as a category 3 hurricane that night. The storm weakened further over land, but emerged back into the Gulf of Mexico by that afternoon. By this time, the hurricane was rounding the edge of a subtropical ridge, and turned more toward the north. The southern Gulf of Mexico was still quite favorable for development and the core reorganized. After bottoming out at category 1, Delta was on the rise again by late on the 7th.
An eye finally cleared out on October 8 as the storm vaulted back up to major hurricane intensity. Delta reached a secondary peak of 120 mph winds and a pressure of 953 mb (its lowest yet) that night, but it soon entered a region of smaller oceanic heat content in the northern Gulf. Simultaneously, a fall frontal system increased southwesterly shear drastically. This fortunately weakened the storm on October 9th. It turned north-northeast and then made landfall in western Lousiana that afternoon as a category 2. Though top winds were down, Delta brought strong winds, storm surge, and flooding rains to the same region that Hurricane Laura had devastated just months earlier. In addition, the storm was the 10th of the season to make landfall in the United States, the most on record.
Rapid weakening ensued once the storm moved inland, toward the northeast. It weakened to a remnant low by the morning of October 10 over western Mississippi. The remnants moved across the eastern U.S., eventually bringing downpours across the mid-Atlantic region a few days later.
The image above shows Delta as it regained major hurricane strength in the Gulf of Mexico on October 8.
Delta was yet another hurricane in the Gulf of Mexico, and a second hurricane landfall for western Lousiana alone.
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