Subtropical Storm One (1978)

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Subtropical Storm One
Subtropical Storm ( SSHWS )
Satellite image of the storm.
Satellite image of the storm.
Emergence January 18, 1978
resolution January 23, 1978
Peak wind
speed
45  mph (75  km / h ) (sustained for 1 minute)
Lowest air pressure 1002  mbar ( hPa ; 29.6  inHg )
dead 0
Property damage 0 US $ (1978)
Affected
areas 		open Atlantic
Season overview:
1978 Atlantic hurricane season

Subtropical Storm One of the year 1978 was the only known subtropical or tropical cyclone that has formed in the Atlantic basin in January. It was built on January 18 a good distance east-northeast of the Leeward Islands, and during its migration it followed a generally westerly course. The storm reached its greatest strength with wind speeds of 75 km / h. Before it broke up on January 23, it only briefly endangered the northeastern Caribbean islands.

Storm course

Track of the storm

In mid-January, a high trough in the west wind zone formed a near-surface low pressure area east-northeast of the Antilles. The low developed south of a subtropical ridge and was thereby isolated from the adverse effects of the westerly wind zone. Its development was of an extra-tropical nature and initially it intensified baroclinically from the meeting of cold and warm air. The convection improved slightly in combination with the low pressure area, although the water surface temperature was relatively low at 24 °  C. On January 18 at 12:00 UTC , the system had organized itself into a subtropical low pressure area about 2,800 km east-northeast of Puerto Rico .

The National Hurricane Center (NHC) began examining the system using the Dvorak technique at 12:00 AM UTC on January 19 and found a value of T2.5; at this point the system showed both tropical and subtropical features. On the same day, the pressure gradient between the storm and the subtropical ridge generated winds at gale strength. The system maintained a generally westerly course throughout its existence, but initially moved in a west-northwest direction. On the morning of January 20th, the convection in the center of the storm was minimal and the rain bands formed cyclonically around the well-developed center. In the course of the day the band structure improved and the storm intensified, reaching its greatest intensity with wind speeds of 75 km / h. This strength was determined by both ship observations and Hurricane Hunter flights.

Late on January 21st, the outer rain bands south and east of the storm center began to disappear and after the storm had maintained its peak intensity for about 36 hours, the trend to weaken began. At that point, the cyclone was on a west-southwest course and one of the forecast models suggested it would be over Hispaniola in 72 hours . At noon on January 22nd, the wind speed dropped below storm force after the convection collapsed near the center. The system then turned more west and away from land, and by January 23rd the circulation had turned into a trough some 300 km north of the Leeward Islands.

Impact and weather records

Satellite image of the storm as it weakened north of the Lesser Antilles.

The storm was the first and so far only subtropical cyclone that has formed in January since the beginning of systematic weather records. This month is the only month of the year in which the formation of tropical or subtropical activity was recorded only once. However, storms formed twice in late December and persisted into January. The second Hurricane Alice of 1954 developed in the same region and passed over the Lesser Antilles in early January 1955 as a light hurricane. The other storm was Tropical Storm Zeta , which existed over the open Atlantic from December 2005 to January 2006. The NHC later (1992) pointed out that subtropical cyclones have only been systematically tracked since 1968 and that there is a possibility that systems previously designated as extra-tropical could have been subtropical.

As was customary at the time, the subtropical storm was not given a name from the list of tropical cyclone names .

Individual evidence

  1. ^ A b c Miles B. Lawrence: Atlantic Hurricane Season of 1978 ( English , PDF) American Meteorological Society. 1979. Retrieved March 7, 2013.
  2. ↑ JBL: Tropical and Subtropical Cyclone Classification on Subtropical Storm One (1) ( English , JPG) SSFS / Miami NHC. January 19, 1978. Retrieved November 2, 2008.
  3. ↑ MM: Tropical and Subtropical Cyclone Classification on Subtropical Storm One ( English , JPG) SSFS / Miami NHC. January 20, 1978. Retrieved November 2, 2008.
  4. ↑ SCT: Tropical and Subtropical Cyclone Classification on Subtropical Storm One ( English ) SSFS / Miami NHC. January 20, 1978. Retrieved November 2, 2008.
  5. ↑ MM: Tropical and Subtropical Cyclone Classification on Subtropical Storm One (JPG) SSFS / Miami NHC. January 21, 1978. Retrieved November 3, 2008.
  6. ↑ National Hurricane Center: SANBAR Model Forecast for Subtropical Storm One ( English , JPG) on January 21, 1978. Retrieved on 3 November, 2008.
  7. ↑ JBL: Tropical and Subtropical Cyclone Classification on Subtropical Storm One ( English , JPG) SSFS / Miami NHC. January 21, 1978. Retrieved November 3, 2008.
  8. ↑ a b c NHC Hurricane Research Division: Atlantic hurricane best track ( English ) NOAA. 2008. Retrieved November 3, 2008.
  9. ↑ National Hurricane Center: Subtropical Storm One Preliminary Report ( English , GIF) 1992. Retrieved November 4, 2007.

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