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Hurricane Matthew: The Cone of Uncertainty

5 Oct 2016, 7:05 am

Hurricane Matthew is a powerful tropical system barreling through the Caribbean, heading for the southeast US. With each subsequent forecast issued by the National Hurricane Center (NHC), you may notice some differences in where the storm will impact. Some large, some small. Why so many changes? You may have seen us show a graphic known as spaghetti plots. It’s a mapping of several individual computer models’ different output for the path of the storm. Here’s what Matthew’s looks like:

C Spaghetti

As you can see, there is pretty good agreement on the general path, but lots of small discrepancies on how far west it goes and whether or not it makes landfall. But it’s these small differences that could mean BIG changes in the intensity and track of this storm. That’s why the NHC issues their forecasted path along with a cone of uncertainty. That’s the yellow cone paralleling the potential path. The wider it is, the more uncertainty and less confidence in the forecast. It generally widens farther out in time.

C Path

Because small changes in path could have big changes in impact, WeatherNation and the NHC encourage you not to focus on the exact path, but rather the wider potential and preparations for all scenarios. Plan for the worst, hope for the best.

C Watch Warn

There are several factors globally that will determine the path of this storm. A large ridge of high pressure in the Atlantic that will move west. As it does so, the clockwise flow around the high will steer Matthew northwest through the Bahamas today and toward the southeast US tomorrow. Beyond that, a trough of low pressure will move through the US and kick it northeast, hugging the Georgia and Carolina coast.

C Set Up

You may be thinking, “Didn’t a previous forecast have it making landfall?” Yes, it did. And future paths could include landfall. That is why it’s important to prepare now. Here’s a good example of possible impacts changing based on the path position. Here is a look at the current forecast for rainfall due to Matthew for the southeast US through Saturday morning:

C Current Rain Forecast

If you shift that path 50-100 miles west or east, those totals could change drastically. Not to mention the strength of the wind, amount of storm surge, etc. Look at Jacksonville. The current forecast has about 6″ of rainfall possible. Shift that west 50 miles, it could be closer to ten. Move it in the other direction and they could see 2-4″.

C West Rain Forecast

C East Rain Forecast

We will continue to keep you posted on WeatherNation on all of the possible scenarios, updated forecasts, and information as it becomes available. Be safe and be weather aware!

For WeatherNation, Meteorologist Karissa Klos

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