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How to read a spaghetti model, 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 have by now seen a bevy of graphics and conversation on social media featuring brightly colored spaghetti models, or spaghetti plots, scattered all around the Gulf and the Florida peninsula.

While these graphics have gained traction with the public in recent years, meteorologists urge caution in placing too much faith in the possible tracks these models present.

Spaghetti models are a combination of different model ensembles. It shows the different paths a storm may take, but neither is it a crystal ball. A spaghetti model does not forecast a storm’s strength or potential impact. They are a simple way of communicating where a storm may travel given the data available at the time. Generally, they are used by meteorologists to give a geographical 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 the “Euro” model. The GEFS generates 21 ensemble models, while the ECMWF generates 51. Together, along with some specific models for tropical systems, these models create different “runs” of the data which are visualized in the spaghetti plot.

“More than likely, the next run [of the data] is going to change,” Jeff George, director of the Florida Public Radio Emergency Network said.

George said that this is especially true when the models are in their formative stages, like when before a storm is officially named. So, making a determination about a storm’s path too far out from a storm’s potential landfall may do more harm than good. This is why meteorologists constantly analyze updated models to better understand how the storm is evolving and how it may impact land.

“With ensemble models, you can have upwards of 90 forecasts. That helps us see better where a storm may go,” Assistant Professor of Meteorology at the University of Florida Stephen Mullens said.

Mullens said there is so much variation between the models because they need to get very small details correct. That includes small details pertaining to the storm, but also, the environment its track takes it through. Water temperature, wind shear and other factors can make a big difference in how the storm develops.

“With this current storm, we are looking at landfall in the next seven or eight days. Right now, it’s time to go through the checklist of responsibilities. Once you’re about four or five days out, you want to start preparing your home.”

Watches are typically issued within 48 hours before landfall. But by this point, Mullens said, you should be wrapping up your preparations. Warnings are typically issued within 36 hours before landfall. Getting prepared ahead of time will help with the anxiety of an oncoming storm, Mullens said, instead of scrambling 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 are yet to be determined by the models.

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

George said follow trustworthy sources like the National Weather Service and the National Hurricane Center. Models update constantly, so you may not even realize you’re looking at an outdated piece of 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. Make sure to stay up to date with information from local emergency management should your region be affected by evacuation orders or closures.