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More tropical trouble may develop off the East Coast

AccuWeather logo AccuWeather 9/14/2021 Alex Sosnowski

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This image, captured on Tuesday, Sept. 14, 2021, shows a disorganized mass of clouds, showers and thunderstorms north of Hispaniola. However, this area may evolve into a tropical depression or storm in the coming days as it drifts northwestward and closer to the United States. (CIRA at Colorado State/GOES-East)

AccuWeather forecasters are closely monitoring an area of showers and thunderstorms east of the Bahamas for potential development into the next tropical depression or storm of the already busy 2021 Atlantic hurricane season. The slowly organizing feature may approach the East Coast of the United States, with the possibility of heavy rain for some coastal areas and dangerous seas for a larger part of the Eastern Seaboard.

The area of unsettled weather caught the attention of AccuWeather forecasters this past weekend, and they say there's a medium chance for development into a named storm. The feature is associated with a storm in the middle layer of the atmosphere. Over time, this storm can spin down to the lower part of the atmosphere, where tropical systems dwell.

The tropical trouble spot will drift farther to the west and northwest as it becomes better organized through Wednesday, although meteorologists expect that process won't happen quickly in this case.

"When there is a suspect area in the tropics this time of the year, we tend to look for reasons why a system will not form with the two big inhibiting factors being wind shear and dry air," AccuWeather Chief On-Air Meteorologist Bernie Rayno said Tuesday while discussing the western Atlantic feature.

diagram © Provided by AccuWeather

Wind shear, or rapidly changing winds in the horizontal or vertical, can disrupt an established tropical system or prevent one from forming in the first place. In some cases, wind shear can assist with strengthening when an established tropical system moves parallel with the shear. Meanwhile, dry air can prevent showers and thunderstorms from becoming numerous and strong.

"There is neither significant wind shear nor dry air around the system at this time, so there seems to be a little better than 50-50 chance it will develop as it drifts northwestward toward the southeastern coast of the United States during the middle part of this week," Rayno said.

There is no indication that the feature will undergo explosive development in the short term, but there is a chance for a tropical depression or storm to form from Wednesday into Friday. Waters over this part of the Atlantic basin are sufficiently warm and generally in the 80s F. Water temperatures of 78 degrees or higher are considered to be high enough to allow tropical depression formation and nurture a developed tropical system.

The next two names on the list of tropical storms for the 2021 Atlantic hurricane season are Odette and Peter. There's another tropical trouble spot farther out in the open waters of the Atlantic that will be in competition for the next name of the season. The potent system recently emerged from Africa and has a chance of developing into a tropical depression and storm in the short term over the eastern Atlantic.

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There is a range of scenarios in the future track of the western Atlantic system during the second half of this week and this weekend, according to AccuWeather meteorologists.


One scenario allows the system to take a steady curved path close to the Carolina coast first and then up near the mid-Atlantic and New England coasts. In this scenario, the system would be drawn in and then picked up by a dip in the jet stream. This track would allow rain and locally gusty winds to reach these coastal locations.

Another possible track is that the system will stay far enough offshore to prevent rainfall along the East Coast.

A third possibility is that the storm may make a loop off the U.S. East Coast, where it could first approach then back away from the Eastern Seaboard. This looping action could happen more than once, and the system could still be lurking just off the East Coast well into next week as a result.

At this time, AccuWeather meteorologists are predicting that some drenching rain may reach the Carolinas due to the approach of the system in the western Atlantic as well as the approach of a cold front from the Midwest.

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Some moisture from Nicholas may get involved as well. Nicholas made landfall along the upper Texas coast Monday night as a Category 1 hurricane as is forecast to lose wind intensity as it moves farther inland, but it will still raise the risk of flooding as a tropical rainstorm over the Southern states in the coming days.

Regardless of whether or not the new system being watched develops into a tropical storm, stormy conditions are anticipated to agitate Atlantic waters along the East Coast of the U.S. later this week and this weekend.

The increased wave action is likely to make for rough surf and strong rip currents from the Carolinas northward to southern New England. Low-lying areas along the Atlantic that are prone to flooding at times of high tide may experience some problems as the system unfolds.

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Beach, boating, cruise and shipping interests should monitor the situation as conditions may deteriorate during the middle and latter part of this week over the western Atlantic between the U.S., the Bahamas and Bermuda.

AccuWeather will continue to provide updates on the tropical weather situation along the Atlantic coast and in more distant waters.

Even though the 2021 Atlantic hurricane season is still behind the pacing of the record 2020 season, it continues to run well ahead of the average pace. Based on data from 1991-2020, an average hurricane season produces 14.4 named storms, of which an average of 7.2 develop into hurricanes and 3.2 of those storms become major hurricanes.

The season is just past the halfway point, and already 14 named tropical storms, six hurricanes and three major hurricanes (Category 3 or stronger) are in the books for 2021. The number of named systems and major hurricanes has already reached the end-of-season averages. In comparison, the entire 2020 season brought 30 named systems with 14 hurricanes and seven major hurricanes.

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AccuWeather is projecting 20-25 named tropical storms with as many as 10 hurricanes and five to seven major hurricanes in 2021. One or two more systems may have a direct impact on the U.S., following eight so far.

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