1978 January subtropical storm
Subtropical Storm One of 1978 was the only known subtropical or tropical cyclone that has formed in the Atlantic basin in January. He was born on January 18, a good bit east-northeast of the Leeward Islands and during his turn, he followed a generally westerly course. The greatest strength reached the storm with wind speeds of 75 km / h Before he disbanded on 23 January, he threatened only briefly the northeastern Caribbean islands.
Storm History
In mid-January fancied lying in the west wind zone level trough a near-surface low-pressure area east-northeast of the Antilles from. The low developed just south of a subtropical ridge and was therefore insulated from the adverse impact of the west wind zone. Its development was of extratropical nature and initially it intensified baroklinitisch or from the meeting of cold and warm air. The convection improved slightly in conjunction with the low-pressure area, although the water surface temperature was relatively low at 24 ° C. On January 18 at 12:00 UTC clock, the system was organized in a sub-tropical low pressure area, about 2800 km east- northeast of Puerto Rico.
The National Hurricane Center (NHC ) began with the investigation of the system by the Dvorak technique at 0:00 clock UTC on January 19 and found a value of T2, 5; at this time showed the system both tropical and subtropical features. On the same day, the pressure gradient between the storm and the subtropical ridge winds gale force generated. The system kept during its existence in a generally westerly course, but moved initially in west-northwest direction. On the morning of 20 January, the convection was minimal in the center of the storm and the rain bands were formed cyclonically around the center well trained. During the day improved the band structure and the storm intensified, with winds of 75 km / h reaching its greatest intensity. This strength was determined both by ship observations as well as by Hurricane Hunter flights.
Late on January 21, the outer rain bands began to disappear south and east of the storm center and after the storm had about 36 hours to maintain its peak intensity, thus continuing a trend of stagnation. At this time, the cyclone was on a west- south-westerly course and one of the predictive models suggested that it would be located within 72 hours of Hispaniola. At noon of January 22, the wind speed dropped below gale force after the convection had collapsed near the center. The system then turned more to the west and away from the land and on 23 January, the circulation had changed into a trough, about 300 km north of the Leeward Islands.
Effects and Weather Records
The storm was the first and so far only subtropical cyclone that has formed in the month of January since the beginning of systematic weather records. This month is thus the only month of the year in which once the formation of tropical or subtropical activity was recorded. However, twice in late December storms have formed which persisted until into January. The second Hurricane Alice of 1954 developed in the same area and moved in early January 1955 low impact on the Lesser Antilles 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 reported later ( 1992) suggest that subtropical cyclones are systematically tracked only since 1968 and the possibility existed that previously might have been subtropical as extratropical designated system.
As was customary at the sub-tropical storm did not receive a name from the list of names of tropical cyclones.