Beryl has grown into a hurricane in the Atlantic and is forecast to strengthen into a major storm as it nears the Caribbean.

Tropical Depression Lisa has moved into southern Mexico a day after making landfall as a hurricane in the Central American nation of Belize and heading inland over northern Guatemala.

Hurricane Lisa has made landfall on the Caribbean coast of Belize.

There are many ways to categorize a hurricane. The storm’s central pressure is one way. The height of its storm surge is another. How much rain it drops is another. And, of course, the strength of its wind is another. But what causes a hurricane to strengthen or weaken? The answer is simple enough, but multifaceted.

Watch live satellite images and an animated forecast cone of Hurricane Ida as it churns through the Caribbean Sea toward the Gulf Coast.

Watch live satellite images and an animated forecast cone of Hurricane Ida as it churns through the Caribbean Sea toward the Gulf Coast.

Tropical Storm Ida has formed in the Caribbean and forecasters say it's aimed at the U.S. Gulf Coast, prompting Louisiana’s governor to declare a state of emergency and forecasters to announce a hurricane watch for New Orleans.

Hurricane experts were closely watching the Caribbean, where Tropical Storm Iota formed Friday afternoon. The National Hurricane Center in Miami said Iota could bring dangerous wind, storm surge and as much as 30 inches (76 centimeters) of rainfall to northern Nicaragua and Honduras. The storm was located about 350 miles (560 kilometers) south-southeast of Kingston, Jamaica and had maximum sustained winds of 40 mph (65 kph). Iota is a record-setting 30th named storm of this year’s extraordinarily busy Atlantic hurricane season. Earlier, firefighters in Tampa had to rescue around a dozen people who got stuck in storm surge flooding on a boulevard adjacent to the bay.

Watch live satellite tracking of Hurricane Dorian as it crosses the Caribbean Sea, crawling toward a vulnerable Puerto Rico. Update as of 2 p.m. Wednesday:Forecasters say Dorian has reached hurricane strength as it nears the U.S. Virgin Islands. Shortly before 2 p.m. EDT, the National Hurricane center reported Hurricane Dorian was expected to move near or over the U.S. and British Virgin Islands during the afternoon and then move over the open Atlantic, east of the southeastern Bahamas. Follow live Dorian tracking below:Dorian made a last-minute shift in its path on Tuesday, threatening Puerto Rico with a direct hit. By Wednesday afternoon the National Hurricane Center said Dorian has become a hurricane as it nears the US Virgin Islands.

Watch live satellite tracking of Hurricane Dorian as it crosses the Caribbean Sea, crawling toward a vulnerable Puerto Rico. Update as of 2 p.m. Wednesday:Forecasters say Dorian has reached hurricane strength as it nears the U.S. Virgin Islands. Shortly before 2 p.m. EDT, the National Hurricane center reported Hurricane Dorian was expected to move near or over the U.S. and British Virgin Islands during the afternoon and then move over the open Atlantic, east of the southeastern Bahamas. Follow live Dorian tracking below:Dorian made a last-minute shift in its path on Tuesday, threatening Puerto Rico with a direct hit. By Wednesday afternoon the National Hurricane Center said Dorian has become a hurricane as it nears the US Virgin Islands.

Watch live satellite tracking of Tropical Storm Dorian as it crosses the Caribbean Sea, crawling toward a vulnerable Puerto Rico. Follow live Dorian tracking below:Tropical Storm Dorian made a last-minute shift in its path on Tuesday, threatening Puerto Rico with a direct hit as forecasters said it could reach near-hurricane strength in its approach to the U.S. territory. The storm is expected to pass over or near western and central Puerto Rico on Wednesday as authorities warned of landslides, widespread flooding and power outages. "Practically the entire island will be under sustained tropical storm force winds," said Roberto Garca, director of U.S. National Weather Service San Juan, during a press conference late Tuesday. Meanwhile, Tropical Storm Erin formed well off the U.S. East Coast on Tuesday night.