Hurricane Dora (1999)

Hurricane Dora

Category 4 major hurricane (SSHWS/NWS)
Hurricane Dora at peak intensity
Formed	August 6, 1999
Dissipated	August 23, 1999
Highest winds	1-minute sustained: 140 mph (220 km/h)
Lowest pressure	943 mbar (hPa); 27.85 inHg
Fatalities	None reported
Damage	Minimal
Areas affected	Hawaii, Johnston Atoll
Part of the 1999 Pacific hurricane season and the 1999 Pacific typhoon season

Hurricane Dora was one of few tropical cyclones to track across all three north Pacific basins. The fourth named storm, third hurricane, and second major hurricane of the 1999 Pacific hurricane season, Dora developed on August 6 from a tropical wave to the south of Mexico. Forming as a tropical depression, it gradually strengthened and was upgraded to Tropical Storm Dora later that day. Thereafter, Dora began heading in a steadily westward, before becoming a hurricane on August 8. Under warm sea surface temperatures (SST's) and low wind shear, the storm continued to intensify, eventually peaking as a 140 mph (220 km/h) Category 4 hurricane on August 12. While passing south of Hawaii, Dora significantly fluctuated in intensity, ranging from winds of 140 mph (220 km/h) to a low-end Category 1 hurricane. While crossing the International Dateline on August 20, Dora weakened to a tropical storm. After weakening to a tropical depression on August 22, the storm dissipated on August 23 while centered several hundred miles north of Wake Island.

Although it never made landfall, Dora produced high surf, gale-force winds and light rain across southeastern Hawaii and Johnston Island. There were no reported deaths or injuries from the hurricane.

A tropical wave emerged into the Atlantic Ocean from the west coast of Africa on July 23. It tracked through the Atlantic and Caribbean Sea for several days with minimal development. By August 4, the system entered the Pacific Ocean, accompanied by disorganized convection. During the next 24 hours, satellite imagery noted evidence of a low-level circulation, as well as the formation of curved convective banding. As a result, it is estimated that Tropical Depression Seven-E developed at 00:00 UTC on August 6, while located about 335 miles (540 km) south of Acapulco. Three hours later, the National Hurricane Center began issuing advisories on the depression and forecasted significant intensification. Despite initial vertical wind shear, the depression steadily intensified and was upgraded to Tropical Storm Dora later that day. Upon becoming a tropical storm, the National Hurricane Center noted "there would seem to be no reason why Dora should not strengthen", citing decent outflow on the western side of the storm and ocean temperatures of nearly 84 °F (29 °C). Although the center began difficult to locate on satellite imagery on August 7, Dvorak T-numbers did not indicate a decrease in intensity. Tracking west-northwestward and then westward along a decaying subtropical ridge, Dora continued to intensify and was upgraded to a hurricane on August 8 based on the Dvorak technique.