Atlantic hurricane

An Atlantic hurricane is a type of tropical cyclone that forms in the Atlantic Ocean between June and November. These storms have strong, spinning winds around a center with low pressure. They can bring bad weather over a large area, not just close to the center.

These storms start as groups of clouds and thunderstorms over warm water. They grow stronger when they develop a closed circulation near the surface.

Tropical storms have winds of at least 39 mph, while hurricanes need winds of 75 mph or more. In the past, storm names were chosen randomly. In 1953, storms began using set lists of names. If a hurricane causes a lot of damage, its name is retired. Each season usually has about 14 named storms, with 7 becoming hurricanes and 3 becoming major hurricanes of Category 3 or higher. In 2004, Catarina was the first hurricane ever recorded in the South Atlantic Ocean.

Description

An Atlantic hurricane is a type of tropical cyclone that forms in the Atlantic Ocean. These storms happen mostly between June and November. They spin around a low pressure center and create bad weather over a wide area. Hurricanes are groups of clouds and storms that start over warm waters. They are different from tornadoes, which are another kind of spinning storm.

In the North Atlantic and the Eastern Pacific, we call these storms "hurricanes," but in the Western Pacific near Asia, they are called "typhoons." A tropical storm has winds of at least 39 mph, while a hurricane needs winds of 75 mph or more. The United States National Hurricane Center watches for these storms and gives out important updates. It is one of the special weather centers for tropical storms, as decided by the World Meteorological Organization.

Steering factors

Tropical cyclones move because of the air around them, from the ground up to about eight miles high. Neil Frank, who led the National Hurricane Center in the United States, said this is like a leaf in a stream or a brick in moving air. The way air moves around high-pressure and low-pressure areas changes where hurricanes go.

In warm parts of the world far from the poles, storms usually move west and then a little to the north. This happens because of a high-pressure system stretching east to west. South of this high-pressure area, winds blow from east to west. If this high-pressure system weakens, a storm might turn north and then curve back toward the northeast. North of the high-pressure area, winds blow from west to east, pushing storms further east.

Intensity

Tropical cyclones, also called hurricanes, can be grouped by how strong they are. We find their strength by looking at their fastest winds or their lowest pressure. Some very strong hurricanes include Hurricane Allen, Hurricane Melissa, Hurricane Opal, Hurricane Wilma, and Hurricane Gilbert. These storms had very low pressure and very fast winds.

Many of these strong hurricanes stayed powerful even when they reached land. The 1935 Labor Day hurricane was the strongest when it hit land, and Hurricane Melissa was the second strongest. Others, like Hurricane Gilbert, also stayed very strong when they made landfall.

Climatology

See also: Tropical cyclogenesis

Climatology helps us understand the usual patterns of an average hurricane season and can help predict future storms. Most Atlantic hurricanes start from tropical waves in warm waters far north of the equator near the Intertropical Convergence Zone. The Coriolis force is usually too weak to start the storm's spin near the equator. Hurricanes often form in the Gulf of Mexico, the Caribbean Sea, the tropical Atlantic Ocean, and sometimes near the Cape Verde Islands, creating Cape Verde hurricanes. Storms can also grow stronger over the Gulf Stream off the U.S. coast when water temperatures are warm enough.

Most Atlantic hurricanes form between August and November, when conditions are just right. About 97 percent of these storms appear between June 1 and November 30, which is the official hurricane season. On average, there are 14 named storms each season, with 7 becoming hurricanes and 3 becoming major hurricanes (Category 3 or stronger). The busiest time is usually around mid-September.

The official hurricane season starts on June 1 and ends on November 30, but sometimes storms can form outside these dates. Since records began, there have been storms in every month of the year, though they are rare outside the season. The National Hurricane Center (NHC) watches for these storms and gives warnings to keep people safe.

Seasonal variation

Most North Atlantic tropical cyclones form between August 1 and November 30, when disturbances are most common. About 97 percent of tropical cyclones in the North Atlantic develop between June 1 and November 30, marking the modern hurricane season. On average, 14 named storms happen each season, with 7 becoming hurricanes and 3 becoming major hurricanes (Category 3 or stronger). Activity peaks around mid-September.

Though the season starts on June 1, the official end was once October 31 but is now November 30. Still, storms sometimes form outside these dates.

June

June starts the hurricane season, but activity is usually low, with about one storm every two years. Early-season storms often form in the Gulf of Mexico or off the U.S. East Coast.

Since 1851, 81 June storms have formed.

July

July sees very little activity, with about one storm each year. Storms usually form in the eastern Caribbean, the Gulf of Mexico, near the Bahamas, or off the U.S. East Coast.

Since 1851, 105 July storms have formed.

August

August has more storms than July because wind conditions improve. About 2.8 storms form each August.

September

September is the peak month for hurricanes, with about three storms each year.

October

October has fewer storms than September because wind conditions change. About 1.8 storms form each October. Storms in October more often form in the Caribbean and Gulf of Mexico.

November

November usually has only one storm every other year, and major hurricanes are rare.

Off-season

Further information: Off-season storms

Though the season runs from June 1 to November 30, storms can form any month.

Monitoring

The United States National Hurricane Center (NHC) watches tropical weather in the North Atlantic and issues reports and warnings. It is one of the Regional Specialized Meteorological Centers for tropical cyclones, as set by the World Meteorological Organization.

Extremes

See also: List of Atlantic hurricane records

Hurricane Katrina was one of the costliest and deadliest hurricanes in U.S. history.

Hurricane Harvey also caused damage and flooding in Texas.

The year with the most tropical storms was the 2020 Atlantic hurricane season, with 30 storms. The 2005 Atlantic hurricane season had many powerful hurricanes.

The weakest season since 1946 was the 1983 Atlantic hurricane season, with only four tropical storms. The 1914 Atlantic hurricane season was the weakest ever recorded, with just one storm.

Hurricane Wilma was the strongest hurricane ever recorded in the Atlantic.

Hurricane Sandy was a very large hurricane.

The 1899 San Ciriaco hurricane lasted a long time, for over 27 days.

Hurricane Ivan created many tornadoes.

The Great Hurricane of 1780 was a very deadly hurricane.

The Galveston Hurricane of 1900 was the deadliest to hit the U.S. mainland.

Hurricane Katrina and Hurricane Harvey caused a lot of damage.

Trends

See also: Atlantic hurricane reanalysis

Paleoclimatology and historical trends

Studies show that big hurricanes hitting the Gulf Coast change over many years. Sometimes more big hurricanes hit the area, and sometimes fewer do. Scientists think this pattern is linked to a big area of high pressure in the Atlantic Ocean called the Azores High. When this high pressure area moves, it changes where hurricanes travel.

In recent centuries, hurricanes seem to be hitting areas farther north more often. This shift may be connected to changes in Earth’s climate.

Climate change

Since 1979, big hurricanes in the Atlantic Ocean have become stronger. Scientists believe this is linked to changes in Earth’s climate. While the total number of hurricanes each year hasn’t clearly gone up, the ones that form are often more powerful.

Impact

Hurricanes are causing more damage today because more people and buildings are near the coast. Some of the costliest hurricanes ever have happened in recent years. Even though we now have better tools to track storms, it’s clear that the strongest hurricanes are becoming more common.

Names

In the past, storms were given names in different ways. By the mid-1900s, storms only had female names. In 1979, they started using both male and female names. In 1953, storms began using names from a set list. If a storm causes a lot of damage, its name might be retired and not used again. Each season, about 14 named storms happen in the North Atlantic, with 7 becoming hurricanes and 3 becoming major hurricanes.