Hurricane John was forecast to be a tropical storm, but in just one day, the system suddenly blew up into a powerful Category 3, striking the southern Mexico coast on Monday evening. With peak winds of 120 mph, it came ashore two days earlier than anticipated near Marquelia in the state of Guerrero, about 75 miles southeast of Acapulco, triggering a mudslide that killed at least two people and threatening severe flooding that could last for days.
The abrupt, unpredicted rapid intensification from a tropical storm to a major hurricane was eerily reminiscent of Hurricane Otis, which surprised Acapulco less than a year ago as the strongest hurricane to ever strike the west coast of Mexico. While John did not make a direct hit on Acapulco, the city has seen heavy rain and flooding, which is likely to continue as the storm lingers nearby the next few days.
Two people in Guerrero died when a mudslide crashed into their house, the Associated Press reported. In and near Marqueila, roofs were blown off houses, trees blocked highways and power was out along a large portion of the coast.
John had been downgraded to a tropical storm as of Tuesday morning but was producing heavy rain that could add up to 30 inches in isolated areas along the coast through Thursday, likely causing “significant and possibly catastrophic, life-threatening flash flooding and mudslides,” the U.S. National Hurricane Center warned.
What to know about the storm’s leap from tropical storm to major hurricane
At 9 p.m. Central time on Sunday, the Hurricane Center was forecasting John to slowly approach the southern Mexico coast before making landfall on Wednesday as a tropical storm with peak winds of 65 mph, although it said “it is possible that the system could become a hurricane before landfall” due to very warm ocean waters and other atmospheric conditions that were conducive to strengthening.
Instead, John’s peak winds rapidly intensified by 85 mph during the next 24 hours, from 35 mph to 120 mph. It slammed ashore around 9:15 p.m. Monday as the strongest September hurricane on record to hit the state of Guerrero.
Last year, Hurricane Otis made a similar transformation as it approached the same coastline.
Otis stunned forecasters when its winds jumped 90 mph in 12 hours and 115 mph in 24 hours before striking Acapulco last October as a Category 5 with maximum sustained winds of 165 mph. A weather station near Acapulco recorded one of the highest wind gusts ever observed in the world at 205 mph. Most computer models had predicted Otis to become only a Category 1 hurricane.
Hurricane Patricia, which struck a sparsely populated part of the southwestern Mexico coast in 2015, holds the record for largest intensification in one day. Its winds increased by a record 120 mph in 24 hours as it became the strongest hurricane the world has seen, with peak winds of 215 mph.
Studies have shown that more storms are rapidly intensifying due to warming ocean waters linked to human-caused climate change. Like Otis, John was a relatively small storm. Research has shown that smaller storms can strengthen faster than larger ones, making them harder to predict.
Catastrophic flooding possible as storm lingers
The Hurricane Center said Tuesday morning that John has weakened to a tropical storm since coming ashore, its peak winds having dropped to 40 mph. However, a strong band of thunderstorms was continuing to dump heavy rain across parts of southern Mexico.
Whether John remains a tropical storm or depression, or dissipates over land and possibly reforms offshore, the Hurricane Center said “there is high confidence that heavy rains will continue in portions of southern and southwestern Mexico during the next couple of days.”
Rainfall totals were forecast to reach 6 to 12 inches across a large section of Mexico’s southern coast through Thursday. Isolated totals around 15 inches are possible across the coastal areas of Chiapas and western Guerrero, and some isolated locations in southeast Guerrero and southern Oaxaca could even see 30 inches.
“Slow-moving John will continue to bring very heavy rainfall to coastal portions of southern and southwestern Mexico through the upcoming week,” the Hurricane Center said. “This heavy rainfall will likely cause significant and possibly catastrophic, life-threatening flash flooding and mudslides to the Mexican States of Chiapas, Oaxaca, and southeastern Guerrero, particularly in areas near the coast and along the up-slope portion of areas of higher terrain.”
