There are growing signs that the ingredients necessary for a tropical storm or hurricane to form are coming together, with the next tropical threat to the United States brewing in the Caribbean.
Many computer forecast models are predicting a strong tropical storm or hurricane in the Gulf of Mexico by the end of next week, but there is still a lot of uncertainty in the forecast, which could lead to multiple outcomes.
The National Hurricane Center currently lists a medium chance of tropical development in the Western Caribbean or southern Gulf of Mexico within the next seven days. According to the FOX Forecast Center, this chance has been steadily increasing over the past week, with further development beyond the seven days being possible as the development window approaches.
“We're still seeing impacts all along the Gulf Coast, from Texas to Florida,” said Fox Weather meteorologist Steven Morgan.
Assemble the weather puzzle
It will take time for the pieces of the puzzle to come together.
There are strong indications that a weather pattern known as the “Central American Gyre” will form in the coming days.
A gyre is a spreading area of low pressure that forms near or over Central America, fed by moisture flowing in from the Pacific Ocean. Its center produces heavy rainfall that can extend for hundreds of miles and threaten to cause torrential rains, floods and landslides in Central America and more than a dozen surrounding countries.
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However, if water temperatures and upper-level winds become favorable for tropical development, organized low-pressure centers may develop into tropical storms or even hurricanes within the larger gyres. Current water temperatures in the Caribbean are close to the warmest temperatures recorded last season.
The ultimate fate of the tropical development will depend on where the vortex forms, how strong it becomes, and the patterns of atmospheric steering or blocking that occur over the southern United States.
There are four main scenarios for how the forecast could play out, each of which poses a major threat to the U.S. Gulf Coast.
Tropical Threat Scenario 1: A circulation forms but no tropical development occurs.
In this case, atmospheric conditions are right for a widespread low-pressure system to bring rain to Central America, but the right conditions never materialize for an individual low-pressure system to form.
“This storm will have the least impact on the continental U.S., but we don't know what's going to happen in Central America,” Morgan said. “This vortex will also bring a lot of rain, so we're expecting heavy rain from Belize, Guatemala, down to Honduras and south to Panama and Mexico, and the rain alone will be difficult to deal with.”
Tropical Threat Scenario 2: A weak depression develops, but moves westward into Central America.
As low pressure centers form on the northern and western edges of the gyre and high pressure establishes itself over the southern U.S., a block will form across the Gulf of Mexico, steering the storm into Central America instead.
“So we could see continued heavy rainfall (there),” Morgan said. “There could also be some concerns around landslides and mudslides.”
Tropical Threat Scenario 3: Cyclones develop east of the gyre, but in the Caribbean.
In this case, the low pressure center may form on the eastern side of the gyre, but will develop further south over the Caribbean Sea.
The cyclone could eventually move into the Gulf of Mexico, threatening coastal communities.
“Another guiding mechanism that we're watching very closely is a dip in the jet stream as a possible impact associated with it,” said Fox Weather meteorologist Kendall Smith. “And if that's over the eastern U.S., it's likely going to pull this system a little bit further north, which would be of more concern to people who live along the Gulf Coast.”
Tropical Threat Scenario 4: Tropical disturbance develops in the Gulf of Mexico
The most frightening scenario is that a low-pressure system already brewing in the Gulf of Mexico takes advantage of record-high water temperatures to rapidly develop into a hurricane.
Forecasts for developing or unorganized systems are subject to large errors and significant changes.
“Computer forecasts that predict development over the warm waters of the Caribbean or southeastern Gulf of Mexico have it moving north as a tropical storm or hurricane, which could impact the Gulf Coast between Louisiana and Florida by next weekend,” said Fox Weather hurricane expert Brian Norcross. “Computer forecasts that predict development over land or a longer, weaker state will have it stalled closer to Mexico, blocked by high pressure to the north, and drifting across the western Gulf of Mexico. It could still impact the Gulf Coast in some way, but its development will likely take longer, pushing the threat further into the future.”
We're in the middle of hurricane season, so it's no surprise that tropical storms are organizing, and the western Caribbean and southern Gulf of Mexico are prime locations for tropical storms to develop in late September.
“This is something that's going to require a little bit of patience from everybody because nothing's going to move quickly,” Norcross said. “We're talking about next weekend, and everybody from Texas to Florida needs to be watching this, staying informed and seeing how it develops.”
