Tropical Storm Otto was the fifteenth named storm of the 2004 Atlantic hurricane season. Otto formed on November 29, just one day prior to the very last day of the Atlantic hurricane season. Otto formed in the far eastern Atlantic Ocean via baroclinic processes.

Otto caused no damage and no fatalities, because it stayed far away from any land areas.

Otto on December 1
FormationNovember 29, 2004
Dissipation December 3, 2004
Highest winds 50 mph
Lowest pressure 995 mbar
Deaths None reported
Damages None
Areas affectedNone
Part of the 2004 Atlantic hurricane season

Meteorological history

On November 21, a cold front exited the East Coast of the United States and moved slowly to the east before stalling about midway between Bermuda and the Azores early on November 25. Later that day, a strong upper-level trough to the north of the front dug southward and caused the development of an extratropical low along the front about 1000 miles southwest of the Azores at around 0000 UTC November 26. Because of the strong baroclinc effects caused by the upper-level low, the occluded surface low pressure system rapidly intensified and made the transition into a gale later that day. The upper-level trough continued to move to the south and eventually developed a cutoff low to the south of the occluded low on November 26. Both the surface and upper-level low moved to the southwest at a foward speed of 5 to 10 knots in tandem for the next three days. Late on November 28, weak ridging to the north of the upper-level low formed over the surface low, and convective banding began to develop near the low-level circulation center. In addition, surface observations from the Tropical Prediction Center's Tropical Analysis and Forecast Branch (TAFB) indicated that the low's frontal structure had dissipated. Dvorak classifications from various satellite agencies indicate that the low developed into Subtropical Storm Otto at 1200 UTC November 29 while located about 1000 miles to the east-southeast of Bermuda. After forming, Otto moved to the northwest through a weakness in the mid-level subtropical ridge located to the north of the cyclone. Convection continued to increase over the low-level circulation of Otto and Advanced Microwave Sounding Unit (AMSU) satellite-derived temperature data indicated that Otto had acquired enough warm-core characteristics to be considered a tropical storm at 1200 UTC November 30 while located about 700 miles to the east of the island of Bermuda.

Otto shortly after its peak as a subtropical storm.

Over the next two days, Otto meandered over relatively cool water temperatures (approximately 21-23°C) and beneath a region of weak vertical wind shear between an upper-level low located to the south and another to the northeast. The marginally favorable environment provided by these two upper-level lows allowed Otto to maintain deep convection near its center. Otto turned slowly to the southeast on December 1 as north to northwesterly mid- to upper-level flow increased along the east side of an amplifying ridge off the East Coast of the United States. During this time, vertical wind shear increased over the cyclone, causing it to slowly weaken due to the deep convection being displaced from the circulation center. On December 2, Otto weakened to a tropical depression, and the entrainment of mid-level dry air, combined with strong upper-level vertical wind shear, eventually eroded Otto's convection and caused it to degenerate into a remnant low on December 3 while located about 800 miles southeast of Bermuda. For the next two days, Otto's remnants drifted slowly to the south and southwest before dissipating around 1200 UTC December 5 about 800 miles northeast of the northern Leeward Islands.


This was the first time the name Otto was used to name an Atlantic hurricane. Otto was the sixth storm in the Atlantic to be assigned the letter 'O', after Opal in 1995, Olga in 2001, Odette in 2003, Ophelia in 2005, and Olga in 2007.

Lack of Retirement

Due to the lack of effects, the name Otto was not retired in the Spring of 2005 by the World Meteorological Organization. It is on the list of names to be used for the 2010 Atlantic hurricane season.

See Also

2004 Atlantic hurricane season


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