The National Hurricane Center upgraded a subtropical Atlantic disturbance to Tropical Storm Hanna on September 28, 2026, at 11:00 AM AST, making it the eighth Atlantic tropical cyclone of the 2026 season.
Hanna's position at 1500Z on September 28 was 36.6°N, 50.4°W, in the central subtropical Atlantic. Scatterometer data confirmed the system had developed a well-defined surface circulation, with peak winds of 35 to 40 knots recorded southeast of the center. Maximum sustained winds were set at 40 knots, or 45 mph.
Forecaster Brown, who issued the first discussion, noted that deep convection was sitting east of Hanna's center despite westerly shear, and that persistent shear would prevent any meaningful strengthening. Dry air at mid levels, combined with that shear, was expected to cause the storm to weaken after a couple of days.
Forecaster Papin's second discussion, issued later that afternoon, placed Hanna moving east-southeastward at roughly 15 knots on a heading of 115 degrees. Westerly vertical wind shear of 20 to 25 knots was affecting the system, and Hanna's convective structure had grown more disorganized by that point. Papin noted that brief bursts of deep convection on the downshear side could allow slight intensification, and the second discussion forecast winds reaching 45 knots, or 50 mph, at the 12-hour and 24-hour marks.
The NHC said Hanna was expected to continue east-southeastward for 24 to 36 hours before slowing and turning east-northeastward. A low-level ridge south of the Azores was expected to shape that later track. As Hanna slows and turns, shear was forecast to shift toward a more northerly direction, drawing very dry tropospheric air into the circulation.
Strong westerly shear was forecast to persist for 48 to 72 hours. Global models and simulated satellite imagery, including ECMWF and hurricane-regional model runs, indicated deep convection would cease near the 60-hour mark. The NHC, based in Miami, Florida, forecast Hanna to become a post-tropical remnant low around 0600Z on October 1, 2026, and to dissipate entirely by October 2, 2026.