Tropical Storm Sean was the latest to form in the Atlantic

Tropical Storm Sean formed early Wednesday, becoming the last named storm of the 2023 Atlantic hurricane season.

  • The storm is not expected to strengthen much, and there were no warnings for land.

  • The National Hurricane Center estimates the storm sustained winds of 40 mph miles per hour. A tropical disturbance that sustained 39 mph winds deserves a name.

  • As of 11 a.m. ET, the storm was about 780 miles west-southwest of Cape Verde Island.

The Atlantic hurricane season began on June 1 and runs through November 30.

In late May, the National Oceanic and Atmospheric Administration predicted there would be 12 to 17 named storms this year, a “near normal” amount. On August 10, NOAA officials revised their estimate upward, to 14 to 21 storms. Sean is the 18th named storm of the Atlantic hurricane season. After reviewing the unnamed January storm, Hurricane Center officials said it would qualify for a name, bringing the total number of such storms this year to 19.

There were 14 named storms last year, after two extremely busy Atlantic hurricane seasons in which forecasters ran out of names and had to resort to backup lists. (A record 30 named storms occurred in 2020.)

This year has an El Niño pattern, which arrived in June. The occasional climate phenomenon can have wide-ranging effects on weather around the world and usually interferes with the number of Atlantic hurricanes.

In the Atlantic, El Niño increases the amount of wind shear, that is, the change in wind speed and direction from the surface of the ocean or land to the atmosphere. Hurricane formation requires a calm environment, and the instability caused by increased wind shear makes those conditions less likely. (El Niño has the opposite effect in the Pacific, reducing the amount of wind shear.)

At the same time, this year’s elevated sea surface temperatures pose numerous threats, including the possibility of storms intensifying.

That unusual combination of factors made solid storm predictions difficult.

There is a solid consensus among scientists that hurricanes are becoming more powerful due to climate change. While there may be no more named storms at all, the likelihood of major hurricanes is increasing.

Climate change is also affecting the amount of rain storms can produce. In a warming world, air can hold more moisture, meaning a named storm can hold and produce 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.

The researchers also found that storms have slowed down, lingering over areas longer, in recent decades.

When a storm slows over water, the amount of moisture the storm can absorb increases. When a storm slows over land, the amount of rain falling at one location increases; In 2019, for example, Hurricane Dorian slowed to a crawl over the northwestern Bahamas, resulting in a total rainfall of 22.84 inches in Hope Town during the storm.

Other potential effects of climate change include greater storm surges, rapid intensification and wider reach of tropical systems.

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