The Atlantic hurricane season peaks from August to October.
This is the time to have your “go-bag” ready in case you need to evacuate. It is also the time to check hurricanes.gov (National Hurricane Center) on a daily basis, I’ll pass along more information from them later in this column.
Several major storms have fallen outside the hurricane season date range. Tropical Storm Fay hit New Jersey on July 10, 2020; Hurricane Isaias struck on Aug. 4, 2020, and Superstorm Sandy impacted the state on Oct. 29, 2012.
Nonetheless, now is the time to be extra vigilant. It’s a good time to learn more about what the National Hurricane Center track forecast cone is, especially as Tropical Storm Erin is churning in the tropical Atlantic Ocean.
Meteorologists shape the track forecast cone
The National Hurricane Center (hurricanes.gov), a part of the National Oceanic and Atmospheric Administration (NOAA), is responsible for issuing all hurricane forecasts. Whether you follow me, another meteorologist in the news or elsewhere, that information all comes directly from the smart, hard-working folks at Florida International University in Miami.
Formed in 1943, their vision is to be “America’s calm, clear, and trusted voice in the eye of the storm and, with its partners, enable communities to be safe from tropical weather threats.”
Like most meteorologists, they use current observations and computer forecast model data to assist them in their forecasting.
In the spring, our “Tidal Flooding Talk” team of Dan Skeldon (a recognized name in local meteorology) and I interviewed Mike Brennan, director of the National Hurricane Center. You can learn more about the NHC during our conversation on YouTube.
The track forecast cone only predicts the path of the storm’s eye
The shaded area of the forecast cone only represents where the hurricane center forecasts the eye of the storm to go over. It has nothing to do with who will feel the impacts of the rain, wind or storm surge.
As we know, New Jersey experiences rough seas and large swells from tropical cyclones hundreds of miles away. Just last week, the week of Aug. 4, there were dangerous rip currents all over the Jersey Shore from Tropical Storm Dexter, which was never closer than 450 miles from the coastline here.
The center line does not represent storm path probability
The weather community has mostly moved away from showing the “center” line in the hurricane outlooks. It’s usually the line that connects the dots or symbols that show where the storm is forecasted to be located at a certain time.
There’s a good reason for it, too. The center line doesn’t mean anything except simply where the center of the cone is now. It doesn’t mean the hurricane center is most confident about it hitting there in the future.
Let’s use Superstorm Sandy in 2012 as an example. Three days before the storm, the center line was in the Delaware Bay. Turns out, it made landfall roughly 50 miles north of there, in Brigantine.
If the people making decisions on evacuations and emergency preparedness only used the center line, New York City and maybe Monmouth County wouldn’t have made the preparations that they did otherwise.
The track forecast cone covers a five-day forecast
The official forecast from the National Hurricanes Center covers a time span of five days. The location, storm strength, speed and pressure forecast are then given for 12, 24, 36, 48, 60, 72, 96 and 120 hours from the time of the forecast.
You may see computer forecast models run online or on television. Commonly known as “spaghetti plots,” they either show one computer model with slightly different variations to give you a fuller picture of where the storm could go (ensemble forecast), or a host of different computer models plotted on one chart.
While they’re fine to show, do not use this as official guidance in your thinking process. The only official source for hurricane track information is the National Hurricane Center.
The track forecast cones widen over time due to growing uncertainty
The further out from the current time you make a forecast, the more likely something in the forecast will change. You may also know this as the butterfly effect, made famous by the Meteorologist Ed Lorenz.
The National Hurricane Center accounts for that by widening the forecast track as you go out from the 12- to 120-hour forecast. Here is how wide the eye of the storm track forecasts were in 2024.
- 12-hour forecast: 26 nautical miles
- 24-hour forecast: 39 nautical miles
- 36-hour forecast: 52 nautical miles
- 48-hour forecast: 67 nautical miles
- 60-hour forecast: 83 nautical miles
- 72-hour forecast: 100 nautical miles
- 96-hour forecast: 142 nautical miles
- 120-hour forecast: 213 nautical miles.
For reference, the entire Jersey Shore, from Cape May to Sandy Hook, is 111 nautical miles.
Forecasting the track of tropical cyclones has improved dramatically
Due to massive upgrades in computer power, knowledge of meteorology and techniques, the track of Atlantic Basin hurricane forecasts is excellent. Here are a few facts that really stand out to me.
Today’s 72-hour (three-day) hurricane forecasts in 2024 are as accurate as the 24-hour forecasts were in 2000.
The 120-hour (five-day) hurricane forecasts in 2024 are as accurate as the 48-hour forecasts in 2000, and even the 72-hour forecasts during Superstorm Sandy in 2012, demonstrating significant progress in extended-range forecasting.
And my favorite, our five-day hurricane forecasts in 2024 are as accurate as the 24-hour forecasts were in 1970. The Pacific Ocean has seen a similar, vast improvement.
In other words, we have reduced the number of false alarms for evacuations and improved the ability to confidently issue evacuations in recent decades.
The track forecast cone is a 60-70% probability
While the weather community has made tremendous gains in tropical cyclone forecasting, the tropical cyclone is expected to remain within the track 60-70% of the time. Upperclassman-level high-school math is used to come to this conclusion. However, the hurricane center uses this probability to strike a balance between the hurricane’s potential path, and accounting for the uncertainty you get the further out you go.
Opinion: The track forecast cone should show the 75% probability
The National Hurricane Center has made tremendous progress in forecasting the track of tropical storms or hurricanes. At the same time, if you weren’t reading Shore Local, you’d have to dig through the internet to find that the cone you see has only a 60-70% probability of it happening. Therefore, to be more accurate, while also understanding the social science of how the cone is perceived, I believe it’s time to make the forecast cone bigger.
By going to a 75% probability, the storm you’re tracking has a 3 out of 4 chance of being within that forecast.
I asked AI (Grok) to compute the width of the forecast track cone if we used a 75% probability. This is what it came up with, compared to what it is now, with the current probability.
24-hour forecast: 45 nautical miles vs. 39 nautical miles.
120-hour forecast: 245 nautical miles vs. 213 nautical miles.
That would take us back to approximately the size of the forecast cone in 2010. For the increase in accuracy, I believe that’s a reasonable price to pay for getting it right more often.
Joe Martucci, a Certified Broadcast Meteorologist and Digital Meteorologist, is the President and Director of Meteorology for Cup A Joe Weather and Drone. You can connect with him at cupajoe.live.
