Tropical Storm Erin forms, poised to become the first hurricane of 2025 Atlantic season

Boston Globe

4 days ago

The first major hurricane of the season (Category 3 or stronger) does not usually form until Sept. 1. Since 2000, only four seasons have had a major hurricane form before Aug. 16 — when Erin is forecast to intensify to a major hurricane — 2000, 2004, 2005, 2008, and 2024.
The first hurricane of a typical season forms around Aug. 11, so we're just about on schedule in that regard.
Advertisement
Tropical Storm Erin will likely emerge as the first hurricane of the Atlantic season.
Boston Globe
Is there a threat to U.S. landfall?
There is plenty left to unfold as Tropical Storm Erin nears the United States. But as of right now, this storm is set to track generally to the west and eventually curve north around the influential Bermuda High, avoiding a landfall to the US but placing Bermuda in the crosshairs.
The Bermuda High has clockwise wind flow, and wind speeds have been somewhat weaker lately. With weaker winds, storms have a tendency to turn north before reaching the mainland. Long-term modeling is picking this up and suggesting that Erin will turn far enough to avoid the US.
Advertisement
Looking ahead to the possible steering track of Erin, the storm may move up the Atlantic and avoid landfall.
Boston Globe
There's no guarantee that Erin will avoid a US landfall, but it is probable. It'll most likely come down to what weather pattern is timed up near the eastern half of the continent when Erin approaches later this week.
Another model has Erin splitting the uprights between the Bermuda High and a pocket of high pressure sliding east across the Northeast and Eastern Canada. This could help bump Erin away from the coast, but it is far from a lock.
In fact, should this high break down before Erin arrives, I can see a scenario where it could tug Erin a bit closer to the coast. I'm not saying a landfall by any means, but it could get close enough for a few showers and some choppy seas. We'll have a better grasp of that by midweek.
High pressure over Eastern Canada and the Northeast is forecast to help push Erin away from the mainland.
Tropical Tidbits
Hurricanes that made landfall near New England since 1950.
Boston Globe
Why is Erin forecast to develop into a major hurricane?
Simply put, more heat and less wind. Sea-surface temperatures have been hardly above average for much of the Atlantic tropical season so far, but in recent weeks, we've seen temperatures begin to climb.
Take a look at how most of the Northern Atlantic, including the Main Development Region in the tropics, is shaded orange and red, averaging around 2 degrees Celsius (3.6 degrees Fahrenheit) warmer than the average this time of year. The MDR is a vast stretch of the Atlantic from the west coast of Northern Africa to the Caribbean islands.
Sea surface temperatures are running close to 2 degrees Celsius above average.
NOAA
Most of this tropical season has been spent with higher-than-normal wind speeds across much of the Atlantic Basin. Strong winds can rip apart storms as they try to develop while also increasing evaporation rates across sea surfaces, cooling down ocean temperatures.
Advertisement
However, with a weaker Bermuda high lately, the forecast calls for lighter winds across the open Atlantic, which will provide conditions for the gradual development of Tropical Storm Erin to major Hurricane Erin in the coming days.
The North Atlantic will see at or below average zonal wind flow (white to light blue shading) over the next week or so, leading to favorable conditions for Erin to develop into a bona fide hurricane.
NOAA
Remember, New England hasn't seen a hurricane strike since Hurricane Bob in 1991.
Ken Mahan can be reached at