Thursday, June 15, 2023

Busy tropical wave train among factors pointing to uptick in Atlantic activity

 By Alex Sosnowski, AccuWeather senior meteorologist

Published Jun 12, 2023 11:07 AM PDT Updated Jun 15, 2023 5:59 AM PDT









While the Atlantic has turned quiet since Tropical Storm Arlene developed in the Gulf of Mexico in early June, AccuWeather meteorologists are seeing signs that point to some potential trouble spots in the coming weeks. The eastern Pacific may be about to spring to life as well.

Some favorable factors for tropical development, such as warm water, are present in the basin. Still, all of the ingredients for organized tropical storms would need to come together for a named storm to form. Indications, such as a robust train of disturbances emerging from Africa, may lead to development from the south-central Atlantic to the Caribbean, Gulf of Mexico and even just off the United States east coast during the fourth week of June. AccuWeather meteorologists say the chances are low at this point but worth keeping a close eye on for many reasons.

Pattern behind some potential uptick in tropical activity

One annual weather feature that sometimes spurs tropical activity is a feature known as the Central America Gyre. This is a large but slowly spinning area of low pressure located over Central America. This circulation usually extends into the eastern Pacific Ocean, the western Caribbean Sea and the southern Gulf of Mexico, depending on its size.

Since the atmospheric pressure tends to lower within the gyre, thunderstorms tend to flourish. Should a cluster of thunderstorms linger long enough, it may begin to rotate faster than the gyre.

Once this circulation is complete with winds of 35 mph, a tropical depression is born. Should the winds spin even faster, to 39 mph or greater, a tropical storm will be named.

AccuWeather meteorologists believe that both the eastern Pacific and the Atlantic will remain quiet into Friday in terms of tropical activity since the gyre is likely to remain very weak. However, during this time, there will be eruptions of thunderstorms near Central America, and tropical waves (tropical disturbances) will move westward from Africa.

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Chances for tropical development to increase this weekend

As these waves move along, there may be some tropical development in waters surrounding Central America and southern Mexico during the third week and fourth week of June. Dry air may suppress activity over the central and eastern Caribbean, but conditions will trend more moist farther to the west.

This image was captured on Wednesdy, June 14, 2023, and shows thunderstorms erupting over the eastern Pacific (left) just off the coast of Central America (middle). (AccuWeather Enhanced RealVue™ Satellite)

"Development is not out of the question on either the eastern Pacific side or the Caribbean side at this time," AccuWeather Tropical Meteorologist Alex DaSilva said. "While it is not impossible for simultaneous development on both sides, it is usually rare for such an occurrence as there is not often enough energy to support both."

As first alerted about on Monday, AccuWeather meteorologists have outlined low-risk development potential well off the coast of Central America and Southern Mexico for the period spanning Thursday to next Monday.

Should a tropical storm gradually develop into next week over the eastern Pacific, it would be the first of the season and be given the name Adrian. Steering winds should guide any system that forms over the eastern Pacific out to sea.

If an organized system takes shape on the Atlantic side, it would be named Bret since a tropical storm already clenched the first name on the 2023 list, Arlene, when it developed in the Gulf of Mexico early in June. Due to the expected steering winds and its potential proximity to land, any named storm that forms could pose threats to land in the form of rain, wind and rough seas from the western Caribbean to Central America and perhaps the southern United States.

Looking ahead at future tropical threats

"Looking ahead into late June, as the tropical wave train continues across the Atlantic from Africa, one such tropical disturbance may provide another spark over the western Caribbean under the gyre's influence," AccuWeather Long-Range Meteorologist Joe Bauer said.

It is also possible that tropical development may not wait until the tropical wave reaches the western Caribbean. Development could occur as far to the east the eastern edge of the Caribbean or the central Atlantic early next week. That tropical wave would have to overcome a great deal of dry air. However, waters are quite warm in that zone and there is a minimal amount of dust.

Some data support a disturbance that could evolve into an organized tropical system that travels from the western Caribbean to the southern Gulf during the fourth week of June due in part to an abnormally active train of tropical waves emerging from Africa for this point in the season.

Factors behind robust tropical waves this season

AccuWeather meteorologists have noticed more tropical wave activity than usual for so early in the season. Typically, dry air and dust limit this activity, but so far this season, there is a lack of dust and dry air originating from the Sahara Desert.

"Because of the lack of dust, which normally blocks some of the sun's energy, water temperatures are higher than historical average by several degrees Fahrenheit this month," AccuWeather Senior Meteorologist Brett Anderson said.

This warmth has given the tropical wave train a boost so far.

Water temperatures need to be near 80 F with an absolute minimum of 78 degrees for tropical development to occur. Waters are sufficiently warm and at or above these levels over much of the tropical Atlantic, Caribbean, Gulf and part of the eastern Pacific along the coast of Central America. In some locations, water temperatures have surged to between 82 and 84 degrees.

Another zone closer to US waters bears watching

AccuWeather meteorologists will also be watching the zone from the Bahamas to just off the Carolina coast during mid- to late June as there will be a series of weak non-tropical storms as a cold front is expected to stall over this region. Along with this potential spark will be large complexes of thunderstorms that originate from the Rockies and Plains, roll through the Southeast states and then offshore over the Atlantic. Occasionally, these features can evolve into a tropical system if given enough time and the right conditions.

However, in this western Atlantic zone, disruptive winds from the southwest, known as wind shear, may prevent development in the first place.

While nothing is imminent, experts recommend that residents and those with vacation plans constantly stay tuned to forecasts, especially during hurricane season.

The eastern Pacific hurricane season began on May 15 while the Atlantic hurricane season started on June 1. AccuWeather meteorologists expect near-historical-average numbers of tropical systems in the Atlantic this season, but the eastern Pacific may turn "hyperactive" in terms of tropical activity.

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