Near the end of October, shower and thunderstorm activity began to concentrate near the center of a non-tropical low pressure system located over the open subtropical Atlantic. The system moved eastward and separated from the surrounding frontal boundaries. By November 1, it had the characteristics of a subtropical cyclone. Since it was already producing gale-force winds, it was named Subtropical Storm Patty. Patty had a small core where vertical instability supported some deep convection, but the entire cyclone was embedded in a cold air mass, contributing to the "subtropical" designation.
The system strengthened a little and veered south of east, reaching peak sustained winds of 65 mph. On November 2, the storm reached the Azores, passing just south of the western islands before turning east and directly over the eastern islands the following day. Wind shear over the storm increased on November 3 and Patty's strength gradually diminished as it finished its passage over the Azores. Rather unexpectedly, the cyclone transitioned into a fully tropical storm that night. The overall trends did not change, though. Progressively chillier water and high shear snuffed out Patty's remaining thunderstorm activity and it dissipated on November 4. By that time, the system was not far from western Europe; what was left of it brought some rain to Spain and Portugal soon after.
The image above shows Patty as a small subtropical storm on November 2.
Patty brought tropical storm conditions to portions of the Azores.
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