Hurricane John (1994)

Hurricane John
Typhoon John

Category 5 major hurricane (SSHWS/NWS)
Hurricane John near peak intensity to the south of Hawaii on August 24
Formed	August 11, 1994
Dissipated	September 10, 1994
Highest winds	1-minute sustained: 175 mph (280 km/h)
Lowest pressure	≤ 929 mbar (hPa); 27.43 inHg (Likely to be lower)
Fatalities	None reported
Damage	$15 million (1994 USD)
Areas affected	Hawaii, Johnston Atoll, Alaska
Part of the 1994 Pacific hurricane season and the 1994 Pacific typhoon season

Hurricane John, also known as Typhoon John, was both the longest-lasting and the farthest-traveling tropical cyclone ever observed. John formed during the 1994 Pacific hurricane season, which had above average activity due to the El Niño of 1994–95 and peaked as a Category 5 hurricane on the Saffir–Simpson hurricane wind scale, the highest categorization for hurricanes.

Over the course of its existence, it followed a 7,165-mile (13,280-km) path from the eastern Pacific to the western Pacific and back to the central Pacific, lasting 31 days in total. Because it existed in both the eastern and western Pacific, John was one of a small number of tropical cyclones to be designated as both a hurricane and a typhoon. Despite lasting for a full month, John barely affected land at all, bringing only minimal effects to the Hawaiian Islands and the United States military base on Johnston Atoll. Its remnants later affected Alaska.

The origins of Hurricane John were thought by the United States National Hurricane Center (NHC) to be from a tropical wave that moved off the coast of Africa on July 25, 1994. The wave subsequently moved across the Atlantic Ocean and Caribbean without distinction, before it crossed Central America and moved into the Eastern Pacific Ocean on or around August 8. Upon entering the Eastern Pacific the wave gradually developed, before the NHC initiated advisories on the system and designated it as Tropical Depression Ten-E during August 11. The system was at this time moving westwards and located around 345 miles (555 km) to the south-southeast of Acapulco, Mexico. Quickly developing banding features and well-defined outflow, it was upgraded to a tropical storm and named John later that day.

A strong ridge of high pressure over the northeastern Pacific Ocean forced John westward, where upper level wind shear kept John a tropical storm. Intensity fluctuated considerably, however, as shear levels varied. More than once, shear cleared away most of the clouds above John and nearly caused it to weaken to a tropical depression. However, after eight days of slow westward movement across the Pacific Ocean, shear lessened greatly on August 19, and John intensified significantly and was designated as a hurricane at 1700 PDT. During an eighteen-hour period between August 19 and August 20, John further strengthened from a weak Category 1 hurricane to a major Category 3 hurricane. Around 1100 PDT on August 20, it crossed into the central Pacific, the first of three basin crosses John would make.