Hurricane Don weakens to tropical storm
Tropical Storm Don, which had strengthened into a hurricane on Saturday, making it the first hurricane of the 2023 Atlantic season, had weakened to a tropical storm on Sunday morningforecasters said.
Tropical disturbances with 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 sustained winds of 65 mph
Don was about 350 miles from Newfoundland, Canada, on Sunday morning, moving north at 12 mph. It was expected to dissipate by Monday night or Tuesday morning, and it posed no threat to land, the Hurricane Center said.
Don is the fifth tropical cyclone to reach tropical storm strength this year. (The hurricane center announced in May that it reassessed a storm that had formed off the coast of the northeastern United States in mid-January, and determined it to be a subtropical storm, making it the first cyclone of the year in the Atlantic Ocean.)
But that storm was retroactively unnamed, making Arlene, which formed in June in the Gulf of Mexico, the first named Atlantic storm this year. Bret and Cindy soon followed suit, making 2023 the first year since 1968 that there were two named storms in the Atlantic at the same time in June, according to Philip Klotzbacha researcher at Colorado State University who studies hurricanes.
The Atlantic hurricane season begins on June 1 and runs through November 30.
At the end of May, the National Oceanic and Atmospheric Administration predicted there would be 12 to 17 named storms this year, a “near normal” number, the organization said. Last year there were 14 named storms after two extremely busy Atlantic hurricane seasons in which forecasters ran out of human names and had to resort to back-up Greek-letter lists. (There were a record 30 named storms in 2020.)
However, NOAA didn’t express much certainty in its forecast this year, saying there was a 40 percent chance of a near-normal season, a 30 percent chance of an above-normal season and a 30 percent chance of a below-normal season.
There was evidence of above-average ocean temperatures in the Atlantic, which could fuel storms, and the potential for an above-normal West African monsoon season. The monsoon season produces storm activity that can lead to more powerful and longer-lasting Atlantic storms.
This year is also dominated by the intermittent climate phenomenon El Niño, which emerged in June. It could have far-reaching effects on weather around the world, including a reduction in the number of Atlantic hurricanes.
“It’s a pretty rare condition to have both going on at the same time,” Matthew Rosencrans, the lead hurricane forecaster at NOAA’s Climate Prediction Center, said in May.
In the Atlantic Ocean, 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 calm environments to form, and the instability caused by increased wind shear makes those conditions less likely. (El Niño has the opposite effect in the Pacific Ocean, decreasing the amount of wind shear.)
But even in average or below-average years for hurricanes, there’s still a chance that a powerful storm will make landfall.
As global warming worsens, that probability increases. Scientists agree that hurricanes are becoming 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 also affects 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 rain, 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 diminished over the past few decades and are now stagnant for longer periods of time.
When a storm slows down over water, the amount of moisture the storm can absorb increases. When a storm slows over land, the amount of rain that falls in a single location increases; for example, in 2019, Hurricane Dorian slowed to a creep over the northwestern Bahamas, resulting in a total rainfall of 22.84 inches in Hope Town.
Other possible effects of climate change include greater storm surges, rapid intensification, and extended range tropical systems.
Rebecca Carballo And Edward Medina reporting contributed.