Bryan Norcross: Forecast consensus shows a tropical system tracking toward the Gulf next week
Long-range computer forecasts are in much better agreement that a disturbance, tropical depression, or perhaps Tropical Storm Patty could track into the Gulf of Mexico late next week.
Development odds increase in Caribbean as 3 areas being tracked across Atlantic
Forecasters are monitoring three areas in the Atlantic Ocean as hurricane season enters its final month, and the odds for one of them to develop are steadily increasing.
Updated Thursday, October 31, 10:00 AM ET
Happy Halloween! The tropical disturbance we've been waiting for is still a ghost. Nothing is expected to develop until at least the weekend. And now, the various long-range computer forecasts are in much better agreement that the steering pattern will shift, which could allow the disturbance, tropical depression, or perhaps Tropical Storm Patty to track into the Gulf of Mexico late next week.
Satellite imagery shows area where a tropical depression is expected to form.
(NOAA)
The strong high-pressure system across the southern U.S., which has been causing continuous strong winds off the ocean along the Florida east coast and into the northern Caribbean, would have blocked a tropical system from moving north. But since low-pressure development has been in slow motion, that pattern looks likely to shift by the time the disturbance develops, creating an alley to the northwest toward the Gulf.
It will be a process. Broad low pressure near the coast of Colombia will combine with an oncoming tropical disturbance and slowly shift west into the southern Caribbean Sea over the next couple of days. According to the computer forecast models, the combo system will be a large low-pressure gyre that will pull moisture from the Pacific north to the northern Caribbean islands. Recall that a gyre is an expansive rotating system that often develops over Central America late in the hurricane season.
The consensus of the computer forecasts is that an organized tropical disturbance will consolidate from the large gyre next week – although exactly where in the Caribbean isn't clear. A sharp dip in the jet stream extending unusually far south looks likely to energize that development. The National Hurricane Center has the odds in the medium range that this smaller system will develop into at least a tropical depression next week.
Area to watch for tropical development
(NOAA)
As the large gyre circulation shifts west over Central America, the flow around it is forecast to rotate the potential tropical system north and then west toward the Gulf of Mexico. If the computer forecasts are correct, this process will take at least a week, so we are looking farther into the future than we can confidently forecast.
Obviously, we don't like to see tropical systems in the Gulf of Mexico, but there is a high consensus that the hostile upper-level winds across the Gulf and Florida will continue to blow across the northern Gulf coast. In addition, the atmosphere will be quite dry, and the Gulf water has cooled dramatically from its summer peak.
The bottom line is, if a system were to move into the Gulf, the environment doesn't appear likely to support a strong storm – at least based on what we know now.
And remember the important rule the applies: Forecasts for weak or just-developing systems, and especially for systems that haven't even formed yet, are subject to large errors and major changes.