An area of disturbed weather a few hundred miles southwest of Bermuda ramped up to Tropical Depression Five at midday Saturday and has potential to become the next tropical storm of the 2020 Atlantic hurricane season this weekend.
A tropical depression has sustained winds that exhibit a circulation around a weak center. Most depressions have winds above 25 mph but not to exceed 38 mph.
Tropical Depression 5 formed 245 miles to the west-southwest of Bermuda during the late morning hours on Saturday, July 4, 2020.
“This system will move over warm waters and in an environment featuring light wind shear into Saturday night and should allow the depression to intensify into Tropical Storm Edouard with maximum sustained winds of 39 mph or greater,” according to Senior Meteorologist Rob Miller.
If Edouard forms this weekend it would be the earliest fifth named storm on record since the satellite era of the 1960s and 1970s.
“We expect this system will pass to the north and west of Bermuda later Saturday night and early Sunday, then the storm will move over colder ocean waters later Sunday, allowing the storm to lose its tropical characteristics,” Miller said. “By Monday, the storm is expected to become a post-tropical storm as it moves over the northern Atlantic Ocean.”
The system is moving toward the east-northeast around 15 mph, which would bring locally drenching showers and gusty thunderstorms to Bermuda starting late Saturday night and lasting through much of Sunday,” Miller stated.
The National Hurricane Center began issuing advisories on the system at 11 a.m. EDT Saturday.
Other than a brief period of downpours and rough seas and surf, the impact on Bermuda will be minimal even if a tropical storm takes shape. Bermuda relies largely on rainwater for drinking and watering purposes so such a storm would also have some benefits. An inch or two of rain is possible from the system as it moves through the islands on Sunday.
“The feature is not a threat to the U.S. and Canada as steering winds will take the feature away from North America,” Miller said.
The disturbance has arisen in a broad area of lower atmospheric pressure, moisture and low wind shear relative to much of the Atlantic basin and has caught meteorologists’ eyes in the past couple of weeks.
Wind shear is the change in the flow of air at different layers of the atmosphere and over the horizontal area just above the sea surface. Strong wind shear can lead to the demise of established hurricanes and tropical storms and prevent the development of tropical systems in general.
Large tracts of dry air, dust and wind shear have been present over much of the tropical Atlantic basin in recent weeks and are likely to continue through much of July. But, this area along and just off the southeastern coast of the United States is a patch where there is some moisture and somewhat lower wind shear.
Through Sunday, the feature will continue to move over warm water with low wind shear and a moist atmosphere which could aid in the development and moderate strengthening.
“Beyond Sunday, the feature will move into a zone of cooler water, drier air and increasing wind shear northeast of Bermuda, which may prevent development or cause the system to weaken or not gain any more strength,” Miller said.
The same general area along and off the Southeast U.S. coast, which includes the northern Gulf of Mexico and western Atlantic waters could allow a similar feature or two to crop up through mid-July.
The earliest fifth-named tropical storm on record since the satellite era of the 1960s and 1970s is Emily from the blockbuster 2005 hurricane season. Emily became a named storm on July 12 and went on to become a powerful and deadly Category 5 hurricane that tracked through the Caribbean.
The 2005 season brought a record number of tropical cyclones, 31, with 27 named tropical storms and 15 hurricanes. Seven of the storms strengthened into major hurricanes of Category 3 or greater on the Saffir-Simpson Hurricane Wind scale.
Category 3 storms produce maximum sustained winds of 111 mph and up to 129 mph (Category 4 storms have wind speeds of 130-156 mph, and Category 5 storms have wind speeds of 157 mph or higher).
The next names on the list for the 2020 Atlantic season are Fay, Gonzalo and Hanna.
The earliest sixth-named tropical storm on record in the Atlantic is Franklin, which also came to life during the 2005 season. Franklin formed on July 21, near the central Bahamas, and traveled northeastward, well to the east of the U.S. coast. Franklin did not reach hurricane strength.
Should none of the aforementioned features bud into a tropical system, it is not uncommon for there to be a lull in tropical activity during July and early August after an active spring.
This is due to the usual presence of dry air, dust and wind shear over the equatorial part of the Atlantic basin and a lack of non-tropical systems dipping southward from North America which could evolve into a tropical system.
Conditions typically ramp up during late August and September as the strength of disturbances moving westward off Africa, called tropical waves, tends to peak, combined with water temperatures climbing to peak values for the year.
is projecting a busy season ahead with 14-20 named tropical storms with seven to 11 hurricanes and four to six major hurricanes. Four tropical storms are already in the books for the season, with one U.S. landfall.
Cristobal became the earliest “C” named storm in recorded history for the Atlantic on June 2, a feat that typically does not occur until around the middle of August. The storm went on to crash ashore along the U.S. Gulf Coast, where it unleashed flooding. Dolly was the second-earliest “D” named storm ever in the basin, but it moved out to sea without impacting land.