On August 24, an area of low pressure formed in the far western Caribbean, extending over the neighboring Yucatan peninsula. It gradually made its way north and became better organized. On August 26, a closed circulation developed in the Yucatan channel between the northeast peninsula and western Cuba. The system was designated Tropical Depression Ten that afternoon. Steering currents near the depression were initially very weak. As a result, the newly formed center meandered in a counterclockwise loop over the next day, executing a turn toward the south, east, and then finally north by the next day. In the meantime, some dry air was entrained into the circulation from the north and west, but this was not enough to stop the gradual improvement of the cyclone, to the point that it was named Tropical Storm Idalia on the 27th.
Idalia was a large cyclone, and took some time to spin up. A large burst of convection covered the center that evening and slow strengthening ensued, though the center remained close to the northern edge of the convective mass. Meanwhile, a trough over the U.S. finally got the storm moving, generally toward the north. Idalia passed very close to the western tip of Cuba during the evening of August 28, bringing tropical storm conditions to that area. Overnight, a more substantial inner core structure developed and the storm reached hurricane strength early on August 29. By that time, it was accelerating a bit on its northward heading into the eastern Gulf of Mexico.
Gulf waters were extremely warm, near record high temperatures in many locations. It took Idalia some time to build an eyewall, but by late that day it was intesifying rapidly. Though the storm overall was large, the central dense overcast and hurricane-force wind radius were rather small. Likewise, the eye that cleared out on satellite imagery late on the 29th was small. Nevertheless, the storm had become an extremely formidable hurricane by early on August 30, reaching its peak intensity as a low-end category 4 with 130 mph winds and a central pressure of 940 mb. An eyewall replacement began just before landfall, weakening the cyclone slightly, and Idalia made landfall in the "big bend" of Florida around 7:45am local time with maximum winds of 125 mph and a central pressure of 947 mb.
The storm weakened quickly over land and moved northeast, crossing into Georgia while still a hurricane. By the 30th, the center was crossing South Carolina; it moved over the Atlantic later that day. The core had completely eroded by that point and Idalia was down to a tropical storm. It was also transitioning to extratropical thanks to an interaction with the trough to its northeast. The storm was completely devoid of central convection by August 31 and finished extratropical transition that afternoon.
The large circulation of Idalia moved generally eastward toward Bermuda. Its motion gradually slowed on September 1 and windy conditions began on Bermuda, though there was almost no rain associated with ex-Idalia. Some deep convection began to redevelop northeast of the center that evening. However, the storm remained entangled with a front and did not regain tropical characteristics. The storm began to move northeast away from Bermuda on September 3.
The above infrared image shows Idalia at peak intensity as a category 4 hurricane in the early hours of August 30.
Idalia caused significant storm surge in northwest Florida; the shape of the coastline and large continental shelf in that region compounds the risk of storm surge.
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