In just 40 hours, the weather system that became known as Hurricane Patricia grew into the fiercest hurricane ever recorded in the Western Hemisphere, threatening calamity on Mexico’s Pacific Coast, only to fizzle into a weak tropical depression after it came ashore.
Why did that happen?
Hurricane experts said quirky conditions nurtured Patricia to become the fastest intensifying hurricane ever observed in the Western Hemisphere. Its winds topped out at 200 miles per hour by mid-day Friday. Warmer than normal Pacific temperatures, combined with calm atmospheric conditions, helped the storm bulk up.
Veteran hurricane chasers voiced dread at the near-nuclear potential of the Category 5 storm as it approached Mexico’s Pacific coast.
“Still can’t believe what’s just offshore. You’d have to be a Cat-5 idiot not to be scared of it. Despite years and years of chase experience, I’m just in awe of this one,” wrote Josh Morgerman from La Manzanilla in Jalisco state near where the eye of the hurricane passed.
Patricia struck hard at landfall near Cuixmala in Jalisco state, but within hours had degraded to a tropical storm again over Zacatecas state. By noon Saturday, its sustained winds were barely 35 miles per hour and dissipating fast. While property damage was extensive, not a single fatality was reported.
Experts said the dissipation of the storm, caused by hitting rugged coastal mountains in an area with little population, was far less surprising than its colossal and rapid buildup. Hurricanes often weaken dramatically on hitting mountainous terrain. And since no major city was in its path, Mexico was spared a high toll.
But the rapid growth of the system from a collection of thunderstorms Thursday to the most powerful storm ever was all but unexpected.
One factor: ocean temperatures in the eastern Pacific off Mexico currently are averaging about 87 degrees Fahrenheit, perhaps due to the El Nino weather phenomenon, and that’s close to the warmest that’s ever been recorded.
“Those warm waters extended to great depth so as the hurricane moved over those waters and stirred them up, the waters that came to the surface . . . didn’t have a cooling effect,” said Dr. Jeff Masters, director of meteorology at Weather Underground, a weather forecasting service.
“The storm was able to draw a tremendous amount of heat energy out of the ocean,” he added.
Adding to that was a lack of wind in the upper levels of the atmosphere. Such wind can shear updrafts in a building hurricane, weakening it. Without them, Patricia was able to form and strengthen quickly.
A third factor was high humidity. Masters said relative humidity of nearly 80 percent off Mexico’s coast was “a powerful source of energy” for the storm since condensation releases heat energy that a hurricane can use to rev up its winds.
Those conditions helped Patricia intensify its winds by about 100 mph within a day, turning it into a monstrous, powerful storm acting with the force of a tornado near its compact eye.
“At least in the Western Hemisphere, it appears to be the fastest intensification ever of a hurricane,” said David Adams, a tropical meteorologist at the National Autonomous University of Mexico.
Such conditions have existed elsewhere at other times around the globe, but hurricanes rarely form so quickly with such strength.
“Patricia did that, and it reached its maximum potential intensity, and that’s really a rare occurrence. We really don’t understand why it doesn’t happen more often,” Masters said. “We’ve never measured winds that strong anywhere in the world.”
Luckily, the storm made landfall at 6:15 p.m. Friday in a sparsely populated area of Jalisco state with pristine beaches and resorts that primarily serve the ultra rich. Tweets and photos from people on the ground indicate heavy damage and mass flooding in the towns of Cuixmala, Emiliano Zapata, Costa Careyes and Melaque.
One photo showed fronds mostly shorn from palm trees in Costa Careyes, a private luxury resort. The website for Costa Careyes describes the resort as a place where guests experience “spectacular natural beauty, breathtaking setting and sybaritic quality of life.”
But Puerto Vallarta, the Pacific resort city popular with U.S. and Canadian tourists, which is some 50 miles to the northwest, received far weaker winds and less rain. Commercial flights to and from Puerto Vallarta, which had been canceled Friday, resumed Saturday morning.
President Enrique Peña Nieto, in a video message released to the nation, offered a note of distinct relief.
“The early reports confirm that damage has been less than what a hurricane of this magnitude could cause,” Peña Nieto said. “Nevertheless, it is very important that people stay in shelters. Security forces are patrolling the streets to protect your homes.”
Later in the day, Peña Nieto flew to Manzanillo, a port in Colima state, where property damage appeared heavy from rains and flash flooding. Photos from Colima and neighboring Michoacan state showed homes damaged by landslides.
Tens of thousands of evacuees remained in more than 1,000 shelters set up at army barracks, schools and other facilities in Colima, Jalisco and Nayarit states.
Mexico’s National Meteorological Service said the tropical storm was moving quickly past Zacatecas state toward the northeast at 21 miles per hour.
If Mexicans felt they dodged a bullet, as Patricia slalomed on a path that spared major population centers, they had reason. Patricia marked the first Category 5 hurricane to land in North America since 2007, when Hurricane Felix hit the sparsely populated border between Honduras and Nicaragua.
Many areas did get heavy rain, though. The heaviest rain fell on the snow-capped Nevado de Colima, an active volcano in southwestern Jalisco state. The Meteorological Service said it recorded slightly more than 15 inches of rain there. Also hit hard with rain was Lazaro Cardenas, Mexico’s most important deepwater port, located in Michoacan state. It got 10 inches of rain, the service said.