During the third week of July, a tropical wave moving through the Caribbean began to exhibit thunderstorm activity near its northern end over the Greater Antilles. Due to land interaction and wind shear, the disturbance did not develop further for the next few days. Around July 21, a broad surface low formed in the Florida straits, bring scattered storms to much of the eastern Gulf region and Florida. It slowly consolidated over the next day, ultimately becoming Tropical Depression Eight late on July 22.
A ridge over the southern U.S. kept the depression moving west-northwestward across the open Gulf of Mexico, though at a slow forward speed. On July 23, Eight's structure improved drastically and the central pressure dropped, but winds lagged behind. It wasn't until late that night that the storm was upgraded to Tropical Storm Hanna. Hanna added to the growing list of records set by its predecessors, becoming the earliest "H" storm. The previous record-holder was Harvey of 2005, which formed on August 3 of that year (not to be confused with the devastating Hurricane Harvey of 2017, which retired the name). At the time of naming, Hanna had vigorous convection in the southern and eastern semicircles, but the northwest struggled some with dry air. This led to the formation of a curious mid-level eye feature, even with the cyclone still a minimal tropical storm! The mid-level center was not yet vertically aligned with the surface circulation due to a bit of wind shear, so Hanna wasn't quite ready to strengthen more rapidly.
On July 24, the storm turned more to the west and filled in more in the northwest quadrant, leading to faster intensification. On top of extremely warm ocean waters, these favorable factors were enough to boost Hanna to hurricane status by the morning of July 25. By that time, tropical storm conditions were affecting the south Texas coastline, and a large eye became increasingly evident on satellite and radar imagery. Hanna's central pressure dropped steadily through the afternoon despite increasing proximity to land. It reached its peak intensity as a high-end category 1, with 90 mph winds and a central pressure of 973 mb, just before landfall in south Texas.
As it made landfall, Hanna took a dive to the west-southwest, angling towards northern Mexico. It weakened to a tropical storm and soon crossed the international border, but maintained an impressive radar signature throughout the next day. By the afternoon of the 26th, the storm weakened to a tropical depression. The next day it weakened to a remnant low and dissipated over the mountains of northern Mexico.
The above images shows Hanna at landfall in south Texas.
Hanna's slow track through the western Gulf of Mexico allowed it ample time to strengthen into a well-organized category 1 hurricane.
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