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Could Hurricane Jose come to LI? Look to the cone of uncertainty.

The cone of uncertainty for Hurricane Jose, as

The cone of uncertainty for Hurricane Jose, as of Sunday evening, Sept. 17, 2017. Photo Credit: National Hurricane Center

What is Hurricane Jose’s cone of uncertainty?

Those who are following news of Hurricane Jose may have seen its track in a cone-like image, showing the storm heading north toward Long Island, then veering to the east.

Indeed, the National Weather Service’s Upton office pointed to it Friday in a tweet, saying: “Much of our area is now in the five-day cone of uncertainty. Be prepared for potential impacts Tuesday/Wednesday.”

What the cone is

The cone shows the range of potential paths for the center of the storm and is not indicating the size of the storm and where major impacts may be. There can be plenty of impacts outside that cone.

People can “mistakenly interpret the size of the cone as the size of the storm or its impacts. Nope,” wrote Marshall Shepherd, director of the atmospheric sciences program and professor at the University of Georgia.

As of late Saturday, the cone showed Jose ultimately passing southeast of Long Island, according to the National Hurricane Center. Even though Jose is looking to make a turn well to the east, the region could see rain and swells.

Room for error

Issued and updated regularly by the National Hurricane Center, it’s not known in weather circles as “the cone of uncertainty” for nothing.

When it comes to longer-term forecasts, the hurricane center says that it’s off on average by about 175 and 225 miles, respectively, for its four and five day looks ahead.

The cone’s track record? “Statistically, two-thirds of all cyclones stay within this cone, while one-third strays outside the cone,” according to a briefing from the weather service’s Upton office.

Still, as the years progress and forecasting becomes more accurate, the size of the cone lessens, says I. Ross Dickman, meteorologist in charge at the weather service’s Upton office.

That is because the cone’s size is based on a portion of the previous five years worth of forecast errors. The more on target the forecasts, the less spread that is needed to capture the uncertainty.

Those who want to delve into the intricacies of how the cone is formed, can look on the National Hurricane Center website.

Some shorthand

Here is what the different parts of the cone of uncertainty mean, when looking on weather websites:

Orange circle: present location of the tropical cyclone, which is the umbrella term for depressions, storms and hurricanes.

White section of cone: where cyclone is forecast to be in one to three days

Dotted section of cone: where cyclone is forecast to be in four to five days

D: tropical depression, with winds under 39 mph

S: tropical storm, with winds of 39 to 73 mph — this is when it gets a name

H: hurricane, with winds of 74 to 110 mph

M: major hurricane, with winds more than 110 mph — yikes!

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