Bermuda High’ System Shifts, Bringing Tropical Weather to the East Coast

0 Share Newsweek is a Trust Project member See more of our trusted coverage when you search. Prefer Newsweek on Google to see more of our trusted coverage when you search. A sprawling high-pressure system over the Atlantic Ocean is expected to help funnel tropical moisture into the eastern United States this week, bringing several days of sticky, uncomfortable conditions to parts of the Mid-Atlantic and Northeast .

Forecasters are closely watching the Bermuda high, a semipermanent weather feature that develops over the North Atlantic during summer and plays a major role in shaping weather across the East Coast, as its position has moved differently from what is expected for the season.

Alex DaSilva, lead hurricane expert and meteorologist at AccuWeather, told Newsweek : “The Bermuda high has been positioned further to the west in the last week or so than what is typical for this time of year. It is expected to continue to be in this position at least through early next week."

Forecast maps show deep tropical moisture spreading from the Southeast into the Mid-Atlantic and Northeast through the second half of the week, raising humidity levels and increasing the potential for heavy downpours in some areas.

The Bermuda High is a large area of high pressure over the North Atlantic Ocean that takes its name from Bermuda, the British Overseas Territory located about 650 miles east of North Carolina.

It is a semipermanent subtropical high-pressure system that naturally shifts east and west throughout the year. During summer and early fall, it is often positioned in the western Atlantic near Bermuda, while during winter and spring it is more commonly centered closer to the Azores.

The system's clockwise circulation influences weather across much of eastern North America. When it becomes stronger or extends farther west, it can draw warm, moisture-laden air northward from the Atlantic Ocean, Gulf of Mexico and Caribbean.

Forecasters say the Bermuda high is forecast to become established closer to the East Coast than is typical, helping channel tropical air into the eastern United States.

"While it's slightly unusual for the Bermuda high to be this far west at the start of August, it is not unheard of. The Bermuda High does move east and west throughout the year. It also grows and shrinks in size. This is why sometimes hurricanes go safely out to sea and other times they are forced into the Southeast U.S.," DaSilva said.

The position of the high matters because its clockwise circulation acts like an atmospheric conveyor belt. When the system expands westward, it can transport warm, moisture-laden air from the tropical Atlantic, Caribbean and Gulf of Mexico northward.

In the coming days' forecast, the National Oceanic and Atmospheric Administration ( NOAA ) has predicted heavy downpours across large parts of the East Coast and beyond while temperatures stay high. The result could be days of muggy conditions, warm nights and a heightened risk of heavy downpours.

"The high is acting like a conveyor belt bringing warm and humid air up from the tropics and bringing it to the East Coast. The high will also help to bring the risk for daily showers and thunderstorms across much of the Southeast," DaSilva said.

Humidity often has a greater impact on how weather feels than air temperature alone.

When dew points climb into the 70s, the air can begin to feel oppressive because sweat evaporates less efficiently from the skin. That makes it harder for the body to cool itself and pushes heat index values higher than the actual temperature.

The Bermuda High is known for creating exactly this kind of setup. When it strengthens and extends westward, it can funnel hot, humid air far inland, producing stretches of sticky weather from the Southeast to the Northeast.

While temperatures may not be excessively high, DaSilva warned residents should still be cautious: "While not record-breaking heat, the high humidity can still make it feel very hot and caution is urged for people spending long periods of time outside. Residents will be urged to stay hydrated."

The feature is perhaps best known for its influence on tropical systems during Atlantic hurricane season.

Meteorologists closely watch the size, strength and position of the Bermuda high because those factors help determine whether storms curve harmlessly out to sea or track toward the Caribbean, Gulf Coast or U.S. East Coast.

Contact Newsweek editors on this story: Rebecca Flood and Emma Lee-Sang

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