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Subtropical Storm One in 1992 was the first recorded Atlantic subtropical cyclone during the month of April. It formed on April 21 about 600 miles (1,100 km) southeast of Bermuda, and tracking northwestward reached subtropical storm status on April 22. The cyclone attained peak winds of 50 mph (85 km/h) before increased wind shear weakened the storm. It turned to the east, and on April 24 dissipated without affecting land.
On April 21, a low pressure area separated from the prevailing westerlies about 600 miles (1,100 km) southeast of Bermuda, and developed into a subtropical depression at 1200 UTC. The system maintained a large comma-shaped cloud pattern around the low-level circulation. Operationally it was not classified until 27 hours later. Isolated from strong steering currents, the depression tracked northwestward at 12 mph (19 km/h), and intensified into a subtropical storm early on April 22. It gradually became better organized, with a large convective band in the eastern semicircle. Reports from a nearby ship indicated peak winds of 50 mph (85 km/h), with swells of 64.4 feet (19.7 m). The National Hurricane Center remarked the potential for the system transitioning into a tropical cyclone. An approaching trough caused the storm to stall and weaken the deep convection. On April 23, the cyclone weakened to depression status due to strong wind shear. A Hurricane Hunters flight into the system confirmed the weakening, and also reported a 1.8° F (1° C) temperature rise in the center, suggesting a warm core and some tropical characteristics.
Early on April 24, the subtropical depression turned eastward, maintaining limited convection. At the time, forecasters anticipated the depression would continue east-northeastward and become an extratropical cyclone. By late on April 24, the system was too weak to classify using the Dvorak technique, and the NHC ceased issuing advisories. Within 24 hours, the circulation dissipated as the system continued eastward through the westerlies.
The storm was the first Atlantic subtropical cyclone on record to develop in the month of April. Previously, a tropical or subtropical cyclone had developed in every month but April. In its preliminary report on the cyclone, the National Hurricane Center notes, "subtropical cyclones have only been tracked since 1968 (tropical cyclone records go back to 1871) and it is possible some systems that were designated extratropical prior to 1968 could have been subtropical."
- ↑ 1.0 1.1 1.2 1.3 1.4 National Hurricane Center (1992). "Subtropical Storm One Preliminary Report". http://www.nhc.noaa.gov/archive/storm_wallets/atlantic/atl1992/st1/prenhc/prelim01.gif. Retrieved 2007-08-21.
- ↑ 2.0 2.1 2.2 Lawrence (1992). "Subtropical Storm One Discussion One". National Hurricane Center. http://www.nhc.noaa.gov/archive/storm_wallets/atlantic/atl1992/st1/tropdisc/nal0192.001. Retrieved 2007-08-21.
- ↑ National Hurricane Center (1992). "April 22 Ship Data". http://www.nhc.noaa.gov/archive/storm_wallets/atlantic/atl1992/st1/sfcdata/shp2206z.gif. Retrieved 2007-08-21.
- ↑ Jarrell (1992). "Subtropical Storm One Discussion Three". National Hurricane Center. http://www.nhc.noaa.gov/archive/storm_wallets/atlantic/atl1992/st1/tropdisc/nal0192.003. Retrieved 2007-08-21.
- ↑ National Hurricane Center (1992). "Subtropical Storm One Preliminary Report (Page 2)". http://www.nhc.noaa.gov/archive/storm_wallets/atlantic/atl1992/st1/prenhc/prelim02.gif. Retrieved 2007-08-21.
- ↑ Rappaport (1992). "Subtropical Depression One Discussion Seven". National Hurricane Center. http://www.nhc.noaa.gov/archive/storm_wallets/atlantic/atl1992/st1/tropdisc/nal0192.007. Retrieved 2007-08-21.
- ↑ Lawrence (1992). "Subtropical Depression One Discussion Nine". National Hurricane Center. http://www.nhc.noaa.gov/archive/storm_wallets/atlantic/atl1992/st1/tropdisc/nal0192.009. Retrieved 2007-08-21.