For now, Sam is the lone named storm over the Atlantic. As it wanders the ocean, it may clip Bermuda and bring effects to the Canadian Maritimes and Newfoundland. The latest track forecasts for Sam suggest that a direct strike on Bermuda is unlikely, but confidence is low, and it’s too early for the British overseas territory to let its guard down.
Sam peaked in strength Sunday as a 155 mph high-end Category 4 hurricane, just three days after becoming a named storm. It briefly weakened to a Category 3 on Monday before regaining Category 4 strength Tuesday.
As of Tuesday morning, Sam’s peak winds had increased to 130 mph as it moved slowly to the northwest at 8 mph.
Although Sam faltered in strength some Monday, that sputtering was only temporary. The storm was undergoing an eyewall replacement cycle, which happens when the existing eyewall, or ring of intense thunderstorms surrounding its center, shrivels inward and disintegrates while being swallowed by a beefier outer eyewall that closes in and becomes dominant.
All that was visible over the past 24 hours in “under the hood” microwave satellite imagery, which can peer through and beneath the sheet of overcast atop Sam to reveal its inner structure.
Now, with a new eyewall formed and a dense inner core, Sam will probably remain strong for quite some time. The eyewall replacement cycle brought about a broadening of the wind field, which expanded the radius of hurricane-force winds from 30 to 40 miles outward from the center.
The forecast for Sam
Forecasters at the National Hurricane Center note that Sam’s eyewall could shrink again, which would consolidate the strongest winds and amplify their magnitude a bit.
“If Sam’s eyewall is able to contract today, some additional strengthening could occur, and this possibility is reflected in the latest NHC intensity forecast,” the Hurricane Center wrote in a forecast discussion Tuesday.
Sam is being steered around the western periphery of high pressure, which extends from east of Bermuda to the Azores. It’s likely that Sam will slip just east of Bermuda, and the island is no longer in the Hurricane Center’s cone of concern. But with roughly five days to go until Bermuda would experience impacts, remaining vigilant is wise.
After making its closest pass to Bermuda, the majority of weather models simulate a continued path out to sea, but a minority of models highlight the possibility of a westward turn toward the Canadian Maritimes. While this outcome isn’t favored, it does remain on the table in six to 10 days.
Sam will generate large swells as it churns through the Atlantic. The swells “are affecting the Leeward Islands and will spread to portions of the Virgin Islands, Puerto Rico, Hispaniola, the Bahamas, and Bermuda by Thursday or Friday,” the Hurricane Center wrote. “Significant swells will likely reach the east coast of the United States and Atlantic Canada by the weekend. These swells will likely cause life-threatening surf and rip current conditions.”
Other areas to watch
Elsewhere in the Atlantic, the remnants of since-dead Tropical Storm Peter, about 400 miles east-northeast of Bermuda, are working to — once again — regain tropical depression or storm status.
Satellite imagery Tuesday morning revealed sustained deep convection, or strong thunderstorm activity, linked to its almost-exposed low-level center. Assuming winds meet the 39 mph criterion, that would render it a rejuvenated tropical storm.
In addition, there are two other tropical waves between the Lesser Antilles and coastal Africa lined up behind Sam. These are the two waves that could earn the names Victor and Wanda.
Both are given 80 percent or higher chances of becoming a tropical depression or storm over the next five days. Forecast models, however, do not show either of these systems as a threat to land any time soon.
Where the hurricane season stands
This season has been a busy one, and more than two months remain in the official window. It’s likely that Sam will prove the most energetic named storm of the season from the standpoint of accumulated cyclone energy (ACE). It’s a measure of atmospheric energy generated by a storm’s winds during its lifetime, related to a storm’s intensity and longevity.
Sam has racked up 20.6 ACE units, about twice that of Ida. Considering that Sam is expected to be a major hurricane through Saturday, it’s almost certain that the storm will overtake Larry, which generated 32.8 ACE units during its journey from the deep tropics through Newfoundland and toward Greenland.
At present, 102.6 ACE units have been tallied this season, a figure that’s about 27 percent ahead of average and on par with an entire season. This year is set to go in the books as the sixth consecutive above-average hurricane season in the Atlantic.