Patty — 2024

Patty began as an extratropical low in the central Atlantic on 31 October 2024, then lost its frontal structure and developed concentrated convection. It became a subtropical storm on 1 November about 250 nautical miles west-northwest of the western Azores, moved eastward and then east-southeastward, and weakened into a tropical storm by midday 3 November between São Miguel and Santa Maria. The system opened into a trough and dissipated by 12:00 UTC 4 November; its remnants produced rain over parts of Portugal and Spain on 5 November. The storm did not make a direct landfall on any Azorean island, but its center passed about 60 n mi south of Flores on 2 November and roughly midway (20–30 n mi) between São Miguel and Santa Maria on 3 November. Tropical-storm-force conditions affected portions of the Azores, with São Miguel and Santa Maria experiencing a few hours of tropical-storm conditions on 3 November. Patty’s peak intensity occurred around 12:00–18:00 UTC 2 November as a subtropical storm, with estimated maximum sustained winds of 55 kt (about 63 mph) and a minimum central pressure of 982 mb. The system was classified as a subtropical storm at peak and later transitioned to tropical as it weakened. Observed storm surge and rainfall effects were limited. The report documents winds and gusts on the islands — for example, Santa Maria reported a sustained wind of 35 kt with a 48 kt gust at 15:00 UTC 3 November; São Miguel recorded a 38 kt gust at 12:00 UTC 3 November; and Flores reported a 34 kt gust at 13:00 UTC 2 November. The lowest sea-level pressure recorded in the Azores was 991 mb on Faial early on 3 November. No specific coastal surge heights or large rainfall totals were reported as significant in the NHC findings. No direct fatalities were reported. Damage was minor and isolated in the eastern Azores; on São Miguel a landslide in Ribeira Grande and some flooding of homes were reported. There were no monetary damage estimates provided in the report. Notable items: the storm’s formation from an extratropical low into a subtropical then tropical cyclone was not well anticipated in the Tropical Weather Outlooks (development was first given as a low-probability forecast about 24 hours before formation). NHC track and intensity forecasts for Patty performed better than recent five-year averages, with relatively low forecast errors.