Subtropical Storm Patty Lashes Azores with 55-Knot Winds in Rare November Transition
Tropical Storm Patty developed in the central Atlantic on 31 October 2024 from an extratropical cyclone. The system became a subtropical storm on 1 November as convection formed around its circulation center. Patty reached peak intensity on 2 November with maximum sustained winds of 55 knots near the western Azores. The cyclone later became a tropical storm before dissipating over the eastern Atlantic on 4 November.
Storm-Force Low Spawns Patty; Azores Brace for Wind and Rain
Patty began as a storm-force extratropical low over the central Atlantic on 31 October. The system initially maintained frontal characteristics while moving northeastward. During the following hours, the cyclone weakened slightly as it moved away from its original upper-level support.
Satellite observations showed increasing convection near the center of circulation on 1 November. The system developed a broader wind field, a concentrated area of thunderstorms, and characteristics associated with a subtropical cyclone. The National Hurricane Center classified the system as Subtropical Storm Patty at that time.
Patty formed in an environment with sea surface temperatures around 20–22°C. The storm was supported by atmospheric instability that allowed convection to organize despite the relatively cool ocean conditions. Its hybrid structure separated it from a typical tropical cyclone that forms over warmer waters.
The storm turned eastward after formation and moved within stronger mid-latitude atmospheric flow. Patty gradually intensified while maintaining an asymmetric wind field, with the strongest winds positioned mainly south of the circulation center.
The Azores became the primary area affected by Patty. The Portuguese national weather service, Instituto Português do Mar e da Atmosfera (IPMA), monitored conditions across the archipelago as the cyclone approached. Tropical Storm Warnings were issued for portions of the Azores as Patty moved through the region, highlighting the risk of strong winds and heavy rainfall.
Patty passed about 60 nautical miles south of Flores Island around 1800 UTC on 2 November. The strongest winds remained south of the center and did not directly impact the island at peak intensity. However, tropical-storm-force winds and periods of heavy rain affected parts of the Azores, producing minor damage in some locations.
The cyclone’s broad circulation created hazardous marine conditions across nearby Atlantic waters. Coastal communities and maritime operations experienced the effects of strong winds and rough seas during Patty’s passage.
Patty Peaks at 55 kt Near Flores; Transition to Tropical Storm Follows
Patty reached its maximum intensity at 1200 UTC on 2 November while located about 100 nautical miles west of Flores in the western Azores. At that point, the subtropical storm had maximum sustained winds of 55 knots and a central pressure of 982 mb.
After reaching peak strength, Patty began a gradual weakening process. The storm accelerated east-southeastward as it interacted with stronger mid-latitude flow. The upper-level low that supported the subtropical structure weakened, reducing the environmental support for further development.
By 3 November, Patty’s organization changed significantly. Increasing westerly vertical wind shear displaced deep convection away from the center, while dry and stable air reduced thunderstorm activity. The circulation became smaller and more tropical in appearance as the system continued across the eastern Atlantic.
At 1200 UTC on 3 November, Patty transitioned into a tropical storm while located between São Miguel and Santa Maria in the eastern Azores. The system had maximum sustained winds of 40 knots and a central pressure of 990 mb during this phase.
The transition marked a change in Patty’s internal structure. The cyclone no longer depended on the upper-level low that had influenced its subtropical development. Instead, the circulation became increasingly organized around a tropical cyclone core before weakening further.
At 0900 UTC on 3 November, Patty’s central pressure was recorded at 989 mb. By 0300 UTC on 4 November, the pressure had risen to 993 mb as the storm weakened.
Patty Dissipates East of Azores; Remnants Reach the Eastern Atlantic
Patty continued moving eastward after becoming a tropical storm, but unfavorable atmospheric conditions caused additional weakening. Strong wind shear and reduced convection prevented the cyclone from maintaining its previous structure.
The National Hurricane Center recorded Patty with maximum sustained winds of 35 knots before dissipation.
The final advisory placed Patty near 37.9°N and 19.2°W at 0600 UTC on 4 November 2024. At that time, the cyclone had maximum sustained winds of 35 knots and a central pressure of 996 mb.
Patty’s meteorological significance came from its multi-stage transformation across the Atlantic. The storm evolved from an extratropical cyclone into a subtropical storm, reached peak subtropical intensity, transitioned into a tropical storm, and then weakened over the eastern Atlantic.
The final recorded structure of Patty at dissipation featured a weakening tropical circulation near 37.9°N, 19.2°W, with sustained winds of 35 knots and a central pressure of 996 mb.