Hurricanes Beatriz and Adrian Churn Off the Coast of Mexico

Tropical Storm Beatriz developed into a hurricane in the Pacific off the coast of Mexico on Friday morning, the National Hurricane Center said, and was expected to strengthen as its center moved near or over portions of southwestern Mexico through Saturday.

Beatriz was gathering force as another Pacific hurricane, Adrian, continued to move westward away from Mexico on Friday, days after it rapidly intensified to become the first hurricane in the eastern Pacific region this year, the Hurricane Center said.

As of Friday night, Beatriz was about 50 miles southeast of Manzanillo, Mexico, with maximum sustained winds of 85 miles per hour, above the threshold of 74 m.p.h. that makes a storm a hurricane. It was expected to bring strong winds and heavy rain to the country’s southwestern coast, the Hurricane Center said.

A hurricane warning was in effect along a 400-mile stretch of Mexico’s southeast coast, from Cabo Corrientes to Zihuatanejo, while hurricane watches, tropical storm watches and warnings were issued elsewhere.

Beatriz was expected to move away from the west-central coast of Mexico on Saturday evening into Sunday.

Adrian was moving northwest across the Pacific and away from the southern tip of Baja California on Friday, the Hurricane Center said. It had maximum sustained winds of 105 m.p.h.

As of Friday morning, there were no coastal watches or warnings in effect for Adrian, according to the National Weather Service, though the Hurricane Center warned that swells generated by Adrian were affecting parts of the western Mexico and Baja California coasts. “These swells are likely to cause life-threatening surf and rip current conditions,” the center said.

Maria Torres, a meteorologist with the National Hurricane Center in Miami, said earlier this week that people living along the coastal areas of Mexico should monitor the storm and watch for updates from their local meteorology offices, because the storm could “create rip currents and hazardous beach conditions.”

When a tropical storm forms in either the Atlantic Ocean or the Pacific Ocean, it generally moves west, meaning that Atlantic storms usually pose a greater threat to North America. When a storm forms close to land in the Pacific, it can bring damaging winds and rain before moving out to sea.

However, an air mass can sometimes block a storm, driving it north or northeast toward the Baja California peninsula and other parts of the west coast of Mexico. Occasionally, a storm can move farther north, as was the case last year with the post-tropical cyclone Kay, which brought damaging wind and intense rain to Southern California.

Hurricane season in the eastern Pacific began on May 15, two weeks before the Atlantic season started. Both seasons run until Nov. 30.

Complicating things in the Pacific this year is the likely development of El Niño, the weather pattern that can have wide-ranging effects around the world.

In the Pacific Ocean, El Niño reduces the changes in wind speed and direction that are known as wind shear. The instability of wind shear normally helps prevent the formation of storms, so a reduction increases the chances for storms. (In the Atlantic Ocean, El Niño has the opposite effect.)

On average, the eastern Pacific hurricane season generates 15 named storms; eight typically reach hurricane strength, and four become major hurricanes with winds that reach 111 m.p.h. In the Central Pacific, four to five named storms develop or move across the basin each year.

There is consensus among scientists that hurricanes are becoming more powerful because of climate change. Although there might not be more named storms overall, the likelihood of major hurricanes is increasing.

Climate change is also affecting the amount of rain that storms can produce. In a warming world, the air can hold more moisture, which means that a named storm can bring more rainfall, as Hurricane Harvey did in Texas in 2017, when some areas received more than 40 inches of rain in less than 48 hours.

Researchers have also found that storms have slowed down over the past few decades. When a storm slows down over water, it increases the amount of moisture the storm can absorb. When the storm slows over land, it increases the amount of rain that falls over a single location. In 2019, Hurricane Dorian slowed to a crawl over the northwestern Bahamas, resulting in a storm-total rainfall of 22.84 inches in Hope Town.

Research shows that climate change might have other impacts on storms as well, including storm surge, rapid intensification and a broader reach of tropical systems.

Livia Albeck-Ripka, Eduardo Medina, Claire Moses and Mike Ives contributed reporting.