High risk of tropical development, US hurricane threat next week
The potential for dangerous conditions along the United States Gulf Coast will likely ramp up next week as meteorologists anticipate a tropical storm that could strengthen to a hurricane will enter the region.
Editors note: A new forecast has been issued for the growing hurricane threat in the Gulf of Mexico.
AccuWeather Chief Meteorologist Jonathan Porter was live on the AccuWeather Network on Sept. 20 to discuss a storm that could bring impacts to the U.S. later this month.
AccuWeather meteorologists continue to highlight a high risk of tropical development next week from the northwestern Caribbean to the south-central and southwestern Gulf of Mexico. Any system that evolves, regardless of intensity, is likely to threaten the United States along the Gulf coast.
"There is the potential for a tropical storm that forms in this area to strengthen into a hurricane in the Gulf of Mexico," Senior Director of AccuWeather Forecasting Operations Dan DePodwin said, "Historically, a storm moving northward from the Caribbean this time of the year not only strengthens but often rapidly strengthens. Major hurricanes have developed in similar situations in the past."
AccuWeather Chief On-Air Meteorologist Bernie Rayno explained that the jet stream usually directs established tropical storms in the Gulf of Mexico this time of the year.
"Typically, the jet stream tends to pull systems to the north and east that enter the Gulf with a higher probability of a direct strike from Louisiana to the Florida west coast versus the Texas coast," Rayno said.
For this reason, there are likely to be at least indirect impacts throughout the Gulf Coast during the middle and latter part of next week, with escalating impacts in some areas, depending on the track of the tropical feature. Conditions ranging from building surf and seas to the potential for storm surge, damaging winds and flooding rainfall are all possible.
Key development factors
Factors expected to lead to tropical development from the western Caribbean to part of the southern Gulf of Mexico include the formation of the Central America gyre, a large, slowly spinning area of low pressure that makes it easy for showers and thunderstorms to develop and cluster. This gyre is much more common in the spring and later in the autumn.
The second factor will be a dip in the jet stream, which will not only help the gyre to strengthen but also influence the track of a tropical feature after it forms.
"If the jet stream ends up being weak, then a tropical feature can still wander into the western Gulf of Mexico and end up near Texas," Rayno said, "Most likely, though, there is usually enough jet stream influence to pull a system to the north and east at some point."
Another factor is the extremely warm water in the anticipated development zone. Surface water temperatures throughout the Caribbean and the Gulf of Mexico are sufficiently warm.
"The warm water extends hundreds of feet [deep] from the surface in the western Caribbean and the southern Gulf, so that when winds begin to churn the waters, there is minimal cooling of that surface water," AccuWeather Lead Hurricane Expert Alex DaSilva said.
This deep, warm water can also greatly increase the chances of rapid intensification.
Wind shear, or the stiff breezes that blow from one direction or change directions, is another factor that can make or break tropical features.
Strong wind shear can prevent the formation of a tropical storm or cause a tropical storm or hurricane to weaken. When wind shear is low, the circulation around a tropical storm or hurricane is not altered, and the feature can strengthen or maintain intensity. In some cases, a tropical storm or hurricane that moves along with wind shear, which is what could happen in the gulf after a time, can assist with strengthening.
"Should all factors come together, this storm, which is expected to become a hurricane, can be highly impactful and one of the ways this season is remembered," DePodwin warned.
Who should be concerned?
All interests along the U.S. Gulf coast, southeastern Mexico, Cuba and part of Central America should closely monitor the situation through next week. A powerful storm could affect local, state and federal operations, as well as the vacation, fishing, cruise and petroleum industries.
Impacts may extend beyond the U.S. Gulf Coast. Steering breezes can guide a system along for hundreds, even thousands, of miles beyond its initial landfall as a tropical rainstorm.
"With the jet stream configuration that is anticipated late next week and into the following weekend, wind and rain impacts may spread well to the north along the Eastern Seaboard," DePodwin cautioned.
Elsewhere in the Atlantic
One other area currently has a risk of tropical development.
This area lies over the middle of the Atlantic, about halfway between Africa and the Leeward Islands. This zone could develop later next week.
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