Atlantic Tropics Heat Up with Erin Leading the Way
Over the past several weeks, the Atlantic Tropics have been heating up with activity. A little less than two weeks ago, our fourth named storm of the season, Dexter, developed just off the East Coast of the United States. Dexter didn’t amount to much before going out to sea. Last week, Erin emerged and became not only the first hurricane of 2025, but also the season’s first major hurricane and Category 5 storm. Let’s take a look at what’s happening with Erin right now as well as other things occurring in the tropics.
Hurricane Erin
So far, the 2025 Atlantic Hurricane Season has behaved normally by most standards. On average, the fifth named storm doesn’t occur until August 22nd. Dexter developed on August 3rd, which was 12 days ahead of schedule for the fourth named storm in the Atlantic on average. Usually, the season’s first hurricane occurs by August 11th. Last year, three hurricanes developed by this point in the season.
However, Erin became a major hurricane on Saturday morning, which is over two weeks ahead of schedule. The average major hurricane doesn’t occur in the Atlantic Basin until September 1st. In addition, Erin became the latest in a series of Atlantic storms to reach the maximum intensity threshold of Category Five. Since 2015, there have been 11 storms that have intensified to Category Five intensity on the Saffir-Simpson Scale, an average of one per year.
There have been forty-three Category Five Hurricanes since records began in 1850. Nearly half of them have occurred over the last three decades. One quarter of these once unique storms have happened since 2015. Erin rapidly intensified from a strong Tropical Storm with 70 mile-per-hour winds to a Category Five Hurricane with 160 mile-per-hour winds in a little more than 27 hours.
The minimum central pressure in Erin dropped 81 millibars in that same 27 hour period, which averages to a rate of 3.0 millibars per hour. Erin tied for 18th on the list of most intense hurricanes in terms of barometric pressure at 915 millibars, or 27.02 inches. The storm is also tied for 26th on the list of most intense hurricanes in terms of maximum sustained winds at 160 miles per hour.
Latest Advisory on Erin
As of the 11:00 PM EDT advisory from the National Hurricane Center, Erin had lost a bit of her punch. Maximum sustained winds had slackened to 140 miles per hour while its minimum central pressure had risen to 937 millibars, or 27.67 inches. The pressure has risen some 22 millibars or 0.42 of an inch in six hours. The bulk of that rise (21 millibars) occurred over three hours from 5:00 to 8:00 PM EDT.
The culprit in Erin’s recent weakening trend was an eyewall replacement cycle. Looking at the vortex data message from aircraft reconnaissance at 5:00 PM, the eye was closed, but concentric. In addition, the data listed the locations of two eyewalls. The vortex data message at 11:00 PM depicted only one eyewall and a circular shape. So, perhaps the eyewall replacement cycle has completed. It is something to keep an eye on over the next day or so.
Despite this latest stumble by Erin, there is still an opportunity for the storm to strengthen. The SHIPS model forecast at 11:00 PM indicated that Erin could re-intensify to a high-end Category Four Hurricane with winds up to 150 miles per hour within the next 24 hours. The forecast discussion pointed out that Erin is in a low shear and moisture-laden environment, which is conducive to strengthening. One thing is for certain, Erin’s wind field is beginning to expand as forecast and is expected to be a very vast hurricane by midweek.
Rough Surf and Rip Currents in Store for East Coast
With an expanding wind field, Erin could double or triple in size. Forecasts indicate that Erin’s diameter could get as wide as 600 miles by the time it makes its closest approach to the Eastern Seaboard by the middle of next week. Large storms can stir up the ocean quite a bit. Superstorm Sandy proved that in October of 2012 while Hurricane Franklin (2023) and Hurricane Ernesto (2024) are more recent examples.
Looking at some of the wave forecasts for Wednesday into Thursday, wave heights could be anywhere from 10 to 15 feet along the Mid-Atlantic Coast by Thursday morning. The threat of rough surf and rip currents will be at a maximum during that time. The problem with rip currents has already plagued the Jersey Shore over the past week. Two people have lost their lives as a result of deadly undertows at Seaside Heights and Belmar.
Forecasters, lifeguards, emergency managers, and local politicians have been sounding the alarm about staying out of the water, especially when there are no lifeguards around. The mayor of Seaside Heights has gone to extreme measures of closing the beaches when there are no lifeguards present. Even if you are a good swimmer, you could still lose a battle with Mother Nature’s rip currents.
Erin Could be Just the Beginning in the Atlantic
The statistical peak of the Atlantic Hurricane Season is September 10th, which is less than a month away. There is still a good deal of tropical activity to go before the 2025 season is done. In addition, two of the last three hurricane seasons have experienced lulls only to have a very hectic backend. The months of August and September are usually very active as ocean temperatures reach their peak.
Looking out into the rest of the Atlantic, there is another impressive wave that just departed Africa over the past several days. In addition, there is an area of disturbed weather off the Mid-Atlantic coast that is being monitored. The Eastern Atlantic wave currently has a 20 percent chance of development over the next week. Meanwhile, the disturbance off the Mid-Atlantic only has a 10 percent chance of development over the next 48 hours to two weeks.
Eastern and Central Pacific Are Quiet
The Eastern Pacific is currently tranquil. Conditions are likewise in the Central Pacific. No development is expected in either basin over the next seven days. Until last Monday, the EPAC had been quite active. There were 9 storms including five hurricanes and two major hurricanes. Erick was the strongest storm to date as a Category Four Hurricane with 145 mile-per-hour winds.
Meanwhile, the Central Pacific picked up in activity with the emergence of Iona on July 27th. Iona became the basin’s first hurricane of 2025 on July 28th, and intensified to a Category Three storm with 125 mile-per-hour winds well south of the Hawaiian Islands. There have been three named storms in the CPAC including two hurricanes. One of the two hurricanes, Henriette came in from the Eastern Pacific.
Heavy surf at Barnegat Light from Hurricane Ernesto on August 18, 2024.