Brewing tropical storm sailing westward across the Atlantic waters

The tropics are heating up this week as a cluster of showers and thunderstorms located about halfway between Africa and the eastern Caribbean islands continues to show indications of organization and AccuWeather meteorologists believe it is highly likely to become the next tropical storm of the 2023 season at any time this week.

AccuWeather meteorologists are referring to the system as a tropical rainstorm as it already has a concentrated area of rain and thunderstorms. The National Hurricane Center has designated the system as Invest 92L. All eyes will be on this feature as it pushes westward across a zone of abnormally warm waters.

In order for a tropical depression to form, the system must have a well-defined center of circulation with sustained winds of 35-38 mph. Should these winds in the circulation reach 39 mph or greater, a tropical storm will be born and the system will be assigned a name. The next name on the list for tropical storms in 2023 is Bret.

Currently, the ocean water temperatures from the Cabo Verde Islands to the Windward Islands range between 80 to 82 F, or 27 to 28 C, at the surface. Compared to typical mid-June sea surface temperatures, values observed this week are trending several degrees higher than the historical average. The approximate minimum threshold for tropical development is 80 F, or 26 C.

An important factor that has allowed the sun’s rays to warm the Atlantic waters quicker than in previous years is the reduced amount of Saharan dust present. An abundance of Saharan dust across the Atlantic basin can be a limiting factor in suppressing tropical formation. It will result in a very dry air mass overhead and reduces the sun’s energy reaching the ocean’s surface.

During its westward trek across the Atlantic waters, forecasters say that the tropical rainstorm will encounter varying levels of wind shear.

“Currently, this feature is in a pocket of low wind shear, which helps to create an environment conducive to development. However, shear is expected to increase once it approaches the Leeward Islands, and further development may become a challenge,” explained AccuWeather Meteorologist Alex DaSilva.

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Wind shear is the change in direction and speed of winds throughout the various levels of the atmosphere. It can critically influence how vertically stacked and organized a storm can become. As a tropical feature becomes more vertically stacked, it can strengthen and become more organized over the warm ocean waters. Strong vertical wind shear is typically bad news for tropical elements, as it can rip apart the layers stacked throughout the atmosphere.

“On this westward track, it could be near the northeastern Caribbean late in the week and next weekend. As a result, anyone with interests in the eastern Caribbean will want to continue monitoring the progress of this system,” explained AccuWeather Senior Meteorologist Adam Douty.

“As the system nears the eastern Caribbian islands, there is a chance a dip in the jet stream just off the United States Atlantic coast is strong enough to tug the system on a more northwest and northerly course,” AccuWeather Chief On-Air Meteorologist Bernie Rayno said. “However, if that does not occur, a more westerly track will continue.”

If the storm tracks near the islands of the eastern Caribbean, gusty winds and heavy rain could result in sporadic damage, such as downed tree branches, minor roof damage and isolated flooding in low-lying areas.

Forecasters say that as the system passes by, wind gusts of 40-60 mph (60-100 km/h) can occur in close proximity to the storm with an AccuWeather Local StormMax™ of 70 mph (115 km/h). Bands of rain that spread to the Lesser Antilles can result in general rainfall totals of 1-2 inches (25-50 mm) with an AccuWeather Local StormMax™ of 5 inches (125 mm).

Following directly behind the tropical rainstorm is a separate tropical wave that is closely being monitored this week into this weekend. There are some indications that this could be the next piece of energy to watch for potential organization; however, it just remains a zone of loosely organized showers and thunderstorms at this time.

If Bret’s name is gathered, the third name on the list for the 2023 Atlantic hurricane season is Cindy.

AccuWeather meteorologists are also monitoring a potential development zone in the East Pacific basin over the next day or so. An area of low pressure located well off the coast of southwest Mexico has been producing a wide swath of showers and thunderstorms with a low chance of forming into a tropical system. However, conditions are likely to become less favorable for organization by midweek and regardless of development, this feature should not directly impact land.

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