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  • Writer's pictureBryan Norcross

Watching the waters near Central America, but there’s nothing to see at this point

The internet has been buzzing because the long-range computer forecast models were showing some type of system forming in the Gulf next week. We keep an eye on the Gulf this time of year, of course, and now the National Hurricane Center is taking note of the possible development of a system next weekend or early next week.

Broadly speaking, we can see how the ingredients might converge for a system to develop in the Gulf or nearby waters. An area of low pressure is forecast to straddle Central America reaching into the Pacific, the western Caribbean, and the extreme southern Gulf of Mexico. The sprawling low is common this time of year. It’s called the Central American Gyre – a gyre being a large rotating system.

Sometime swirls spin out of the gyre and become independent low-pressure systems that develop into tropical depressions, tropical storms, and sometimes even hurricanes. We’ve seen a number of storms develop this way over the past few years.

There’s no guarantee that’s going to happen. In fact, the odds appear to pretty low into early next week. The gyre is just an ingredient for possible development.

Another piece of the puzzle is often a dip in the jet stream that reaches down, scoops up a piece of the gyre, and pulls it north. One of those scoops is indeed coming along, but how strong it will be and how it will be oriented is unknown. The computer forecast models are coming up with different answers every day, which is not surprising since we’re talking about the details of the weather pattern a week in the future.

The third atmospheric question mark is the location of a patch of supportive upper-level winds over the Gulf or western Caribbean. Does it line up with a system that might develop, or will an area of strong upper winds prohibit anything from organizing.

The bottom line is: The details of the evolution of all of these potential ingredients 5 to 7 days from now are unknowable.

Computer model forecasts for weak or developing systems are always suspect, and forecasts for systems that haven’t even begun to develop are even more so. Although computer forecasts are getting better all the time as more powerful supercomputers are deployed by the National Weather Service in this country and other meteorological centers around the world, reliably predicting when the right ingredients will come together to develop a tropical system is still dicey business.

The consensus of the latest versions of the various computer models continues to show broad low pressure in the vicinity of Central America next weekend into next week. That’s all there is to know at this point.

This whole discussion that blossomed on social media last week brings up an interesting philosophical question: Is it newsworthy that long-range computer models show a possibly dangerous weather system developing a week, 10 days, or more in the future?

Generally speaking, nobody would report on any threat if they knew that key facts behind the potential hazard were unknowable and unverifiable. But it’s routinely done with weather forecasts – citing long-range computer models.

A case could be made that the simple fact that one or more models is showing a threat 5 or 10 in the future is news. But that only works if you don’t think of the models as a weather forecasts – a baby that’s hard to split.

And publicly distributing low-odds weather forecasts for worrisome events, which are likely to change in detail and substance as the week goes by, can only diminish the credibility of the forecasting process and meteorology in general – to nobody’s benefit.

The message right now is: Over the weekend or next week the ingredients might come together to produce a system in the Caribbean, the Gulf, and/or the Pacific. Or they might not. For most people, that’s not worth knowing, and certainly not worth worrying about.


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