Millions of people living along the Gulf Coast are being urged to prepare as there are growing signs that the next tropical threat to the United States is brewing in the Caribbean and that the ingredients for a tropical storm or hurricane are lining up.
Many computer forecast models are predicting a strong tropical storm or hurricane in the eastern Gulf of Mexico by the end of this week, but there is still a lot of uncertainty in the forecast, with multiple outcomes possible.
The system expected to threaten the Gulf Coast has now been named “Invest 97L,” which is simply a naming convention used by the National Hurricane Center (NHC) to run special computer models to help forecasters get additional information on tropical disturbances being monitored for development.
The probability of Invest 97L is steadily increasing, and the NHC says tropical development is likely from the northwestern Caribbean Sea into the southern and eastern Gulf of Mexico over the next seven days.
A widespread area of low pressure is currently producing scattered showers and thunderstorms across the northwest Caribbean and parts of Central America, the NHC said.
“Environmental conditions appear favorable for the development of this system, and a tropical depression or tropical storm is likely to develop as it moves northward across the northwest Caribbean and Gulf of Mexico over the next few days,” the NHC said in its latest tropical weather forecast.
The weather system is expected to bring heavy rain to parts of Central America over the next few days, according to the NHC.
The NHC said areas in the northwest Caribbean, Mexico's Yucatan Peninsula and western Cuba should closely monitor the system's progress.
The NHC said the storm is expected to move north up the Gulf of Mexico later this week and urged people along the northern and northeastern Gulf Coast to remain vigilant.
Where will the Gulf of Mexico tropical disturbance go?
“How strong the storm will be and where its most intense impacts will occur are open questions,” wrote Fox Weather hurricane expert Brian Norcross. “While the various computer forecasts agree on a general level about how steering patterns will shift, the small details make the difference between whether a storm strikes one particular location or another one hundreds of miles away.”
Through Monday, Invest 97L's chances of development are expected to continue to increase, potentially developing into a tropical depression or tropical storm in the Western Caribbean by Tuesday.
A hurricane watch was then issued for parts of the U.S. Gulf Coast, and Tropical Storm Helene could be tracked by the middle of the week, Norcross said.
The storm, whether tropical storm or Hurricane Helen, could make landfall somewhere between Louisiana and Florida on Thursday or Thursday night.
“Residents along the coast between Louisiana and Florida need to be well informed,” Norcross continued, “The situation will evolve quickly, and they should think carefully about what they will do in areas that may be affected if a major storm moves through this weekend.”
By Friday, the storm is expected to move inland across the Southeast and begin to weaken, but will continue to bring heavy rain and gusty winds along its path.
Assemble the weather puzzle
The pieces of this complex weather puzzle are slowly coming together, including a weather pattern known as the Central American Gyre.
Gyres are spreading areas of low pressure that are fed by moisture flowing in from the Pacific Ocean and form near or over Central America.
Essentially, the storm is bringing heavy rainfall that will reach hundreds of miles and threaten to cause torrential rains, flooding and landslides in more than a dozen countries, mostly in Central America.
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 on record last season.
The ultimate fate of the tropical development will depend on the location of the gyre, how strong it becomes, and the pattern of atmospheric steering or blocking that occurs over the southern United States.
