Tropical Storm Don, which strengthened to a hurricane on Saturday, making it the first hurricane of the 2023 Atlantic season, had weakened to a tropical storm by Sunday morningthe forecasters said.
Tropical disturbances that have sustained winds of at least 39 miles per hour earn a name from the National Hurricane Center.
Once winds reach 74 mph, a storm is classified as a hurricane; at 111 mph, it becomes a major hurricane. The National Hurricane Center estimated that Don had sustained winds of 65 mph
Don was about 350 miles from Newfoundland, Canada on Sunday morning and moving north at 12 miles per hour. It was expected to dissipate by Monday night or early Tuesday and posed no threat to landfall, the Hurricane Center said.
Don is the fifth tropical cyclone to reach tropical storm strength this year. (The center of hurricanes announced in May which had reevaluated a storm that formed off the coast of the northeastern United States in mid-January and determined it was a subtropical storm, making it the first Atlantic cyclone of the year.)
But that storm wasn’t retroactively named, making Arlene, which formed in the Gulf of Mexico in June, the first named Atlantic storm this year. Bret and Cindy soon followed, making 2023 the first year since 1968 that there have been two named storms in the Atlantic Ocean in June at the same time, according to Philip Klotzbacha Colorado State University researcher who studies hurricanes.
The Atlantic hurricane season begins June 1 and runs through November 30.
In late May, the National Oceanic and Atmospheric Administration projected there would be 12 to 17 named storms this year, an « almost normal » amount, the organization said. There were 14 named storms last year after two extremely busy Atlantic hurricane seasons, in which forecasters ran out of human names and had to fall back on Greek-letter backup lists. (There was a record 30 named storms in 2020.)
However, NOAA didn’t express much certainty in its forecasts this year, saying there was a 40% chance of a near-normal season, a 30% chance of a better-than-normal season, and a 30% chance of a less-than-normal season.
There were indications of above-average ocean temperatures in the Atlantic, which could fuel storms, and the potential for a higher-than-normal West African monsoon season. The monsoon season produces thunderstorm activity that can lead to more powerful and longer-lasting Atlantic storms.
This year also features the intermittent El Niño weather phenomenon, which arrived in June. It can have far-reaching effects on weather around the world, including a reduction in the number of Atlantic hurricanes.
« It’s a pretty rare condition for both to occur at the same time, » Matthew Rosencrans, head of hurricane forecasting at NOAA’s Climate Prediction Center, said in May.
In the Atlantic, El Niño increases the amount of wind shear, or the change in wind speed and direction from the ocean or land surface to the atmosphere. Hurricanes need a calm environment to form, and the instability caused by increased wind shear makes these conditions less likely. (El Niño has the opposite effect in the Pacific, reducing the amount of wind shear.)
But even in average or below-average years for hurricanes, there’s still the chance that a powerful storm will make landfall.
As global warming gets worse, this possibility increases. There is a consensus among scientists that hurricanes are getting more powerful due to climate change. And while there may be no more named storms overall, the likelihood of major hurricanes is increasing.
Climate change is also affecting the amount of rain storms can produce. In a warming world, the air can hold more moisture, meaning a named storm can hold and produce more precipitation, as did Hurricane Harvey in Texas in 2017, when some areas received more than 40 inches of rain in less than 48 hours.
The researchers also found that the storms have slowed down in recent decades and now remain stationary for longer periods.
As a storm slows down on water, the amount of moisture the storm can absorb increases. As a storm slows down over land, the amount of rain falling on a single location increases; in 2019, for example, Hurricane Dorian slowed to a crawl over the northwestern Bahamas, resulting in rainfall totals of 22.84 inches in Hope Town.
Other potential effects of climate change include increased storm surge, rapid intensification, and tropical systems with a broader reach.
Rebecca Carballo AND Edward Medina contributed report.