The 2005 Azores subtropical storm was the nineteenth nameable storm of the 2005 Atlantic hurricane season that formed out of an upper-level low that was west of the Canary Islands on September 28. On October 4, the low had acquired enough organization to be designated as a subtropical depression. The system was short-lived, however, as it crossed the Azores the same day it became a subtropical depression, then it became extratropical on October 5. No damage or fatalities were reported with this storm.
|Formation||October 4, 2005|
|Dissipation||October 5, 2005|
|Highest winds||50 mph|
|Lowest pressure||997 mbar|
The origins of this storm can be traced to an upper-level low just west of the Canary Islands on September 28. The low gradually became more organized over the next few days, producing several bursts of convection, all the while remaining a non-tropical, cold-cored system. The system was moved gradually west to northwest during this time, as well. Satellite imagery, as well as surface observations, indicated that a broad surface low formed late on October 3, located southwest of the Azores. Early on October 4, convection increased as the surface low became better organized, and at this time, the system was determined to have been a subtropical depression. That morning, the depression moved into a warm sector ahead of an approaching cold front, and it strengthened into a subtropical storm. After that, the subtropical storm continued to the northeast, strengthening slightly more as it did so. As it approached the Azores that evening, it reached its peak intensity of 50 mph winds and a pressure of 997 mbar.
After moving through the Azores, the subtropical storm weakened slightly as it moved to the north-northeast. As it interacted with the cold front, it became extratropical on October 5, with the system becoming fully absorbed into the front later that day. The newly absorbed system would later become Hurricane Vince on October 8. Operationally, it was thought that this subtropical storm was not a subtropical storm, but rather a non-tropical low. However, several post-season findings confirmed that this system was a subtropical storm.
The storm produced tropical-storm force winds throughout parts of the Azores, mainly the eastern portions. The strongest winds of the storm were recorded on Santa Maria Island and São Miguel Island, where sustained winds were reported to be as high as 49 mph, with gusts as high as 59 mph. No damage or fatalities were reported on the Azores in association with the subtropical storm.
Naming and Records
The storm was not classified as an unnamed subtropical storm until April 10, 2006, thanks to a reassessment by the National Hurricane Center. If the storm would've operationally been determined subtropical, it would've been named Subtropical Storm Tammy.
When the depression became a subtropical storm on October 4, it was the earliest that the nineteenth tropical or subtropical storm had formed in the Atlantic basin. The old record was previously held by a storm that formed in the 1933 Atlantic hurricane season on October 25. Finally, this was only the fourth time in the history of the Atlantic basin that a season had 19 storms form.
Lack of Retirement
Because it was unnamed, this storm was not retired in the Spring of 2006 by the World Meteorological Organization. Even if it would've had a name, this storm would not have been retired.