Hurricane Irene–Olivia was the first actively tracked tropical cyclone to move into the eastern Pacific Ocean from the Atlantic basin. It originated as a tropical depression on September 11, 1971, in the tropical Atlantic. The cyclone tracked nearly due westward at a low latitude, passing through the southern Windward Islands and later over northern South America. In the southwest Caribbean Sea, it intensified to a tropical storm and later a hurricane. Irene made landfall on southeastern Nicaragua on September 19, and maintained its circulation as it crossed the low-lying terrain of the country. Restrengthening after reaching the Pacific, Irene was renamed Hurricane Olivia, which ultimately attained peak winds of . Olivia weakened significantly before moving ashore on the Baja California Peninsula on September 30; the next day it dissipated.
In the Atlantic, Irene produced moderate rainfall and winds along its path, although impact was greatest in Nicaragua where it moved ashore as a hurricane. A total of 96 homes were destroyed, and 1,200 people were left homeless. The rainfall resulted in widespread flooding, killing three people in Rivas. In neighboring Costa Rica, Hurricane Irene caused more than $1 million (USD) in damage to the banana crop. Later, the remnants of Hurricane Olivia produced rainfall in the southwest United States. Flooding was reported near Yuma, Arizona, which closed a major highway, and the moisture produced snowfall in higher elevations in the Rocky Mountains.
Meteorological history
The origins of the hurricane were from a tropical wave that exited the west African coast on September 7. It moved rapidly westward, developing into a tropical depression on September 11 about east of the Windward Islands. It was one of seven active tropical cyclones in the Atlantic basin that day, one of the most active single days on record. It existed at a fairly low latitude and failed to intensify due to the unfavorable combination of Hurricane Ginger and a long trough to its northwest. On September 13, the depression passed just south of Barbados and subsequently entered the Caribbean Sea. Interacting with the terrain of South America, the center became broad and ill-defined, although Curaçao reported winds of near tropical storm force as it crossed the island on September 16. It later moved near or over northern Venezuela and Colombia. As it approached the western Caribbean, the depression was able to organize more, with less influence from landmass or the trough to its north. At 0000 UTC on September 17, it is estimated the depression attained tropical storm status; that day, it was named Irene about east of San Andrés. Initially, the storm was expected to track west-northwestward toward the northwest Caribbean, similar to the track taken by the destructive Hurricane Edith two weeks prior.
Tropical Storm Irene gradually intensified as it continued across the southwestern Caribbean Sea. Late on September 18, the storm attained hurricane status a short distance off the coast of Central America, with winds, its peak intensity in the Atlantic Ocean. As it strengthened, it developed an eye and spiral rainbands that extended across Panama into the Pacific Ocean. Hurricane Irene weakened slightly as it approached the coast, although its pressure dropped to 989 mbar. On September 19, the hurricane made landfall in the Nicaraguan South Caribbean Coast Autonomous Region; it was the first tropical cyclone of hurricane intensity since 1911 to strike Nicaragua south of Bluefields. Irene quickly weakened, deteriorating to tropical depression status within 18 hours of moving ashore. The circulation remained organized over the low-lying terrain of southern Nicaragua, possibly due to it crossing Lake Nicaragua. After reaching the Pacific Ocean on September 20, the depression restrengthened to attain tropical storm status; upon doing so, it was re-designated by a new name, Olivia. It was the first time an Atlantic hurricane was tracked as a tropical cyclone while crossing Central America into the Pacific Ocean; subsequent research indicated there were earlier storms that accomplished the feat, although they were not known at the time.