2005 Azores subtropical storm
Encyclopedia
The 2005 Azores subtropical storm was the nineteenth nameable storm of the record-breaking 2005 Atlantic hurricane season
. It was not officially named by the National Hurricane Center
as it was operationally classified as a non-tropical low
. The storm developed in the eastern Atlantic Ocean out of a low-pressure area that gained subtropical characteristics
on October 4. The storm was short-lived, crossing over the Azores
later on October 4 before becoming extratropical
again on October 5. No damage or fatalities were reported. After being absorbed into a cold front
, the system went on to become Hurricane Vince
, which affected the Iberian Peninsula
.
Months after the hurricane season, when the National Hurricane Center was performing its annual review of the season and its named storms, forecasters Jack Beven and Eric Blake identified this previously unnoticed subtropical storm. Despite its unusual location and wide wind field, the system had a well-defined center convecting around a warm core—the hallmark of a subtropical storm.
on September 28. The low organized itself over the next several days, producing several bursts of convection. While remaining non-tropical with a cold core
it moved gradually west to northwest. On October 3, it became a broad surface low about 400 nautical miles (460 mi, 740 km) southwest of São Miguel Island
in the Azores. Early on October 4, convection increased as the surface low organized itself, and the system became a subtropical depression.
Around the same time, the depression turned northeast into a warm sector
ahead of an oncoming cold front and strengthened into a subtropical storm. The system continued to track northeast and strengthened slightly, reaching its peak intensity of 50 mph (85 km/h) as it approached the Azores that evening. After tracking through the Azores, the storm weakened slightly as it moved to the north-northeast. Through an interaction with the cold front early on October 5 the subtropical storm became extratropical. The system was fully absorbed by the front later that day. The newly absorbed system would separate from the dissolving frontal system and become Subtropical Storm Vince
on October 8.
At the time, the system was not believed to have been subtropical. However, there were several post-season findings that confirmed that the system was indeed a subtropical storm. The first was the cloud pattern, in which it had deep convection around the center and was better organized with a well-defined center of circulation. In addition, the system had a warm core more typical of tropical cyclones as opposed to the cold core of extratropical cyclones. The warm-core nature also meant that there were no warm
or cold fronts attached to the system, as temperatures did not change ahead of and behind the system until the unrelated cold front passed the Azores. Satellite imagery suggested that the system was briefly a tropical storm as the warm core was found; however, the widespread wind field and the presence of an upper-level trough confirmed that it was merely subtropical.
, where 10-minute sustained winds reached 49 mph (79 km/h) with gusts to 59 mph (94 km/h). Ponta Delgada
faced 38 mph (61 km/h) winds, with the peak recorded gust being 52 mph (85 km/h). No damage or fatalities were reported.
The storm was not classified as a subtropical storm until April 10, 2006, after a reassessment by the National Hurricane Center. Every year, the NHC re-analyzes the systems of the past hurricane season and revises the storm history frequently if there is new data that was operationally unavailable. If the storm had been operationally recognized it would have been named Subtropical Storm Tammy, and storms forming after October 4 would have been moved one name down the list. Hurricane Wilma
would have been given the name Alpha: a name that, had it been retired like Wilma was, could not be replaced by an "alternate" Greek letter, as is the convention with names on the standard A–W list. When the system strengthened into a subtropical storm on October 4, it was the earliest the 19th tropical or subtropical storm of the season formed. The old record was held by an unnamed storm in the 1933 Atlantic hurricane season
, which formed on October 25, 1933. It was also only the fourth time that 19 storms formed in a season.
2005 Atlantic hurricane season
The 2005 Atlantic hurricane season was the most active Atlantic hurricane season in recorded history, repeatedly shattering numerous records. The impact of the season was widespread and ruinous with an estimated 3,913 deaths and record damage of about $159.2 billion...
. It was not officially named by the National Hurricane Center
National Hurricane Center
The National Hurricane Center , located at Florida International University in Miami, Florida, is the division of the National Weather Service responsible for tracking and predicting weather systems within the tropics between the Prime Meridian and the 140th meridian west poleward to the 30th...
as it was operationally classified as a non-tropical low
Low pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...
. The storm developed in the eastern Atlantic Ocean out of a low-pressure area that gained subtropical characteristics
Subtropical cyclone
A subtropical cyclone is a weather system that has some characteristics of a tropical and an extratropical cyclone. As early as the 1950s, meteorologists were unclear whether they should be characterized as tropical or extratropical cyclones. They were officially recognized by the National...
on October 4. The storm was short-lived, crossing over the Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
later on October 4 before becoming extratropical
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
again on October 5. No damage or fatalities were reported. After being absorbed into a cold front
Cold front
A cold front is defined as the leading edge of a cooler mass of air, replacing a warmer mass of air.-Development of cold front:The cooler and denser air wedges under the less-dense warmer air, lifting it...
, the system went on to become Hurricane Vince
Hurricane Vince (2005)
Hurricane Vince was an unusual hurricane that developed in the northeastern Atlantic basin. Forming in October during the 2005 Atlantic hurricane season, the waters over which it developed were considered too cold for tropical development...
, which affected the Iberian Peninsula
Iberian Peninsula
The Iberian Peninsula , sometimes called Iberia, is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar...
.
Months after the hurricane season, when the National Hurricane Center was performing its annual review of the season and its named storms, forecasters Jack Beven and Eric Blake identified this previously unnoticed subtropical storm. Despite its unusual location and wide wind field, the system had a well-defined center convecting around a warm core—the hallmark of a subtropical storm.
Meteorological history
The system originated out of an upper-level low just west of the Canary IslandsCanary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
on September 28. The low organized itself over the next several days, producing several bursts of convection. While remaining non-tropical with a cold core
Cold-core low
A cold-core low, also known as a cold low or cold-core cyclone, is a cyclone aloft which has an associated cold pool of air residing at high altitude within the Earth's troposphere. It is a low pressure system which strengthens with height in accordance with the thermal wind relationship. These...
it moved gradually west to northwest. On October 3, it became a broad surface low about 400 nautical miles (460 mi, 740 km) southwest of São Miguel Island
São Miguel Island
São Miguel Island , nicknamed "The Green Island", is the largest and most populous island in the Portuguese Azores archipelago. The island covers and has around 140,000 inhabitants, 45,000 of these people located in the largest city in the archipelago: Ponta Delgada.-History:In 1427, São Miguel...
in the Azores. Early on October 4, convection increased as the surface low organized itself, and the system became a subtropical depression.
Around the same time, the depression turned northeast into a warm sector
Warm front
A warm front is a density discontinuity located at the leading edge of a homogeneous warm air mass, and is typically located on the equator-facing edge of an isotherm gradient...
ahead of an oncoming cold front and strengthened into a subtropical storm. The system continued to track northeast and strengthened slightly, reaching its peak intensity of 50 mph (85 km/h) as it approached the Azores that evening. After tracking through the Azores, the storm weakened slightly as it moved to the north-northeast. Through an interaction with the cold front early on October 5 the subtropical storm became extratropical. The system was fully absorbed by the front later that day. The newly absorbed system would separate from the dissolving frontal system and become Subtropical Storm Vince
Hurricane Vince (2005)
Hurricane Vince was an unusual hurricane that developed in the northeastern Atlantic basin. Forming in October during the 2005 Atlantic hurricane season, the waters over which it developed were considered too cold for tropical development...
on October 8.
At the time, the system was not believed to have been subtropical. However, there were several post-season findings that confirmed that the system was indeed a subtropical storm. The first was the cloud pattern, in which it had deep convection around the center and was better organized with a well-defined center of circulation. In addition, the system had a warm core more typical of tropical cyclones as opposed to the cold core of extratropical cyclones. The warm-core nature also meant that there were no warm
Warm front
A warm front is a density discontinuity located at the leading edge of a homogeneous warm air mass, and is typically located on the equator-facing edge of an isotherm gradient...
or cold fronts attached to the system, as temperatures did not change ahead of and behind the system until the unrelated cold front passed the Azores. Satellite imagery suggested that the system was briefly a tropical storm as the warm core was found; however, the widespread wind field and the presence of an upper-level trough confirmed that it was merely subtropical.
Impact, classification, and records
Tropical storm-force winds were reported across parts of the Azores, primarily on the eastern islands. The strongest winds were reported on Santa Maria IslandSanta Maria Island
Santa Maria , Portuguese for Saint Mary, is an island located in the eastern group of the Azores archipelago and the southernmost island in the Azores...
, where 10-minute sustained winds reached 49 mph (79 km/h) with gusts to 59 mph (94 km/h). Ponta Delgada
Ponta Delgada
Ponta Delgada is a city and municipality on the island of São Miguel in the archipelago of the Azores, an autonomous region of Portugal. It includes 44,403 residents in the urban area, and approximately 20,113 inhabitants in the three central parishes that comprise the historical city: São Pedro,...
faced 38 mph (61 km/h) winds, with the peak recorded gust being 52 mph (85 km/h). No damage or fatalities were reported.
The storm was not classified as a subtropical storm until April 10, 2006, after a reassessment by the National Hurricane Center. Every year, the NHC re-analyzes the systems of the past hurricane season and revises the storm history frequently if there is new data that was operationally unavailable. If the storm had been operationally recognized it would have been named Subtropical Storm Tammy, and storms forming after October 4 would have been moved one name down the list. Hurricane Wilma
Hurricane Wilma
Hurricane Wilma was the most intense tropical cyclone ever recorded in the Atlantic basin. Wilma was the twenty-second storm , thirteenth hurricane, sixth major hurricane, and fourth Category 5 hurricane of the record-breaking 2005 season...
would have been given the name Alpha: a name that, had it been retired like Wilma was, could not be replaced by an "alternate" Greek letter, as is the convention with names on the standard A–W list. When the system strengthened into a subtropical storm on October 4, it was the earliest the 19th tropical or subtropical storm of the season formed. The old record was held by an unnamed storm in the 1933 Atlantic hurricane season
1933 Atlantic hurricane season
The 1933 Atlantic hurricane season was the second most active Atlantic hurricane season on record, with 21 storms forming during that year in the northwest Atlantic Ocean. The season ran through the summer and the first half of fall in 1933, and was surpassed in total number of tropical cyclones by...
, which formed on October 25, 1933. It was also only the fourth time that 19 storms formed in a season.
See also
- List of Atlantic hurricanes
- 2005 Atlantic hurricane season2005 Atlantic hurricane seasonThe 2005 Atlantic hurricane season was the most active Atlantic hurricane season in recorded history, repeatedly shattering numerous records. The impact of the season was widespread and ruinous with an estimated 3,913 deaths and record damage of about $159.2 billion...
- Timeline of the 2005 Atlantic hurricane seasonTimeline of the 2005 Atlantic hurricane seasonThe timeline of the 2005 Atlantic hurricane season documents the formations, strengthenings, weakenings, landfalls, extratropical transitions, and dissipations of the season's tropical and subtropical storms. The 2005 Atlantic hurricane season was the most active Atlantic hurricane season in...
External links
- NHC's Tropical Cyclone Report on the storm