How to read a spaghetti pattern, before you start worrying

With a tropical system brewing in the Caribbean, it may become the first storm of the season to reach the Gulf of Mexico. No doubt you’ve already seen a plethora of graphics and social media conversations featuring brightly colored spaghetti models, or spaghetti diagrams, scattered throughout the Florida Gulf and Peninsula.

While these charts have gained traction with the public in recent years, forecasters urge caution in relying too heavily on potential clues these models present.

Spaghetti models are a combination of different model sets. It shows the different paths a storm can take, but it’s not a crystal ball either. A spaghetti model does not forecast the strength of a storm or its potential impact. They are a simple way to communicate where a storm may travel based on the data available at the time. Generally, they are used by meteorologists to give a geographic range to the public.

There are two main ensemble weather models used to forecast tropical systems. They are the GEFS, from the United States, and the ECMWF, or “Euro” model. The GEFS generates 21 ensemble models, while the ECMWF generates 51. Together, along with some models specific to tropical systems, these models create different “runs” of the data displayed in the spaghetti diagram.

“Most likely the next race [of the data] it’s going to change,” said Jeff George, director of the Florida Public Radio Emergency Network.

George said this is especially true when the models are in their formative stages, such as when a storm is officially named. Therefore, making a determination about a storm’s path too far from a storm’s potential landfall can do more harm than good. That’s why meteorologists are constantly looking at updated models to better understand how the storm is evolving and how it may impact land.

“With ensemble models, you can have more than 90 forecasts. That helps us better see where a storm might go,” said Stephen Mullens, an assistant professor of meteorology at the University of Florida.

Mullens said there is a lot of variation between models because they need to correct for very small details. That includes small details related to the storm, but also the environment it passes through. Water temperature, wind shear, and other factors can make a big difference in storm development.

“With this current storm, we expect to make landfall in the next seven to eight days. At this point, it’s time to review the responsibilities checklist. Once you have about four or five days, you’ll want to start preparing your home.”

Watches are generally issued within 48 hours of landfall. But by now, Mullens said, you should be finishing your preparations. Warnings are generally issued within 36 hours of landfall. Preparing ahead of time will help with anxiety about an approaching storm, Mullens said, rather than struggling once the watch is issued.

Mullens emphasizes that the model will absolutely change due to factors in the storm and environmental factors around the storm that have not yet been determined by the models.

“It is definitely important to note that this forecast will change. Over the next two or three days, the models must predict how the eye will form. The question is where [in the Caribbean] will form, and how strong it will become. That will dictate what happens next.”

George said to follow reliable sources like the National Weather Service and the National Hurricane Center. Models are constantly being updated, so he may not even realize that he is seeing outdated information circulating on social media.

Warning residents of a potential storm too early or too late can be a dangerous game. “If we warn too early, or if we warn based on unreliable data, and the storm doesn’t happen as expected,” George said, “then trust and credibility can be damaged. Warning too late gives less time to prepare… it’s a balancing act most of the time.”

Now is the time to prepare for a hurricane or tropical storm if you haven’t already. Be sure to stay up to date with local emergency management information in case your region is affected by evacuation orders or closures.

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