The National Hurricane Center has geared up for the 2020 hurricane season with four changes and improvements to the way it conducts business.

The inclusion of a 60-hour forecast between the existing 48- and 72-hour forecasts, an update to the track forecast cone and using local time for systems in the Eastern Atlantic are among the changes. Though there were two named storms in May, the season officially begins June 1 runs through Nov. 30.

However, South Jersey officials, both in and out of the meteorological community, agree on what the most impactful change will be.

“For us, I truly believe the storm surge inundation graphic will be extremely useful in our evacuation planning and will enable us to pinpoint where we will see the highest surge from an approaching storm system,” said Vince Jones, director of the Atlantic County Office of Emergency Management.

Storm Surge.JPG

Tropical systems will now come with a forecasted storm surge graphic. Storm surge is the rise in sea level solely caused by a storm. 

The addition of storm surge forecast graphic, which will represent the peak height the water could reach above normally dry ground, is an experimental product.

“This graphic will provide a reasonable worst-case scenario, and people can plan accordingly. And they don’t need to think about what datum is being used (such as mean lower low water or mean sea level) since this graphic represents depth of water above the ground,” said Joe Miketta, the warning coordination meteorologist at the National Weather Service in Mount Holly.

Miketta also agreed this was the most important of the four NHC updates.

The changes made for 2020 come after meetings among the NHC, based in Florida, and coastal, local National Weather Service offices, such as Mount Holly, which is responsible for all of the Jersey Shore.

“Changes in forecast procedures, products and services, such as the once scheduled for this year, are usually an outcome from these meetings. However, the NHC and the local NWS offices are in good contact with each other during active events, so needed changes, if any, are often already contemplated and known before these meetings,” Miketta said.

The implementation of a 60-hour forecast is another example of this. The NHC has provided forecasts 120 hours, or five days, out since 2001. However, forecast intervals have been at 48 and 72 hours, among others.

“The inclusion of a 60-hour forecast between the already available 48- and 72-hour forecasts point will provide better definition to the forecast path of the storm. ... In addition, this extra 60-hour forecast point will also include intensity and 34-knot and 50-knot wind ... forecasts as well,” Miketta said.

Using Superstorm Sandy as the example in 2012, anyone viewing the NHC’s 11 p.m. Friday forecast update before the storm’s Monday arrival would more clearly be able to pinpoint when the turn to the west would occur. That change in direction occurred that Monday morning, 60 hours after that 11 p.m. Friday forecast.

Sandy with 60 Hour.JPG

If Sandy were to occur in 2020, the National Hurricane Center would have an additional forecast point at 60 hours. The change "will provide better definition to the forecast path of the storm so users will no longer have to rely on visual linear interpolation if the 60 hour forecast is important to them," said Joe Miketta, Warning Coordination Meteorologist for the National Weather Service in Mount Holly. 

One change that occurs every year, regardless of conference calls with the local NWS offices, is the update to the NHC’s track forecast cone. The cone represents the probable track of the center of a tropical cyclone. Sixty-six percent of historical official forecast errors over a 5-year sample fall within the cone.

Forecast Cone Radii.jpeg

Official cone of uncertainty track over time in the Atlantic Hurricane basin. The margin for error has shrunk between a third to a half since 2005.

The size of the track forecast cone is essentially unchanged for the 2020 season. Of the eight forecast times used in the past five years (3, 12, 24, 36, 48, 72, 96 and 120 hours), only the 48- and 72-hour intervals changed, with an increase of 1 nautical mile. One nautical mile is equal to 1.12 miles.

Atlantic Track Trend.jpg

Official intensity error trend for the Atlantic hurricane basin. The margin for error has declined over time. 

However, dramatic gains have been seen in the track forecast cone since the turn of the century. Ninety-six-hour, or four-day, forecasts are as accurate in 2020 as 48-hour forecasts were in 2000. Seventy-two-hour, or three-day forecasts, have the same accuracy as a storm 24 hours did. Forecasts beyond 72 hours out didn’t exist until 2001.

Improvements in the track forecast cone have “always been something that we as emergency managers understood,” Jones said.

Miketta says that people can expect future NHC improvements to be focused on showing the full range of options a storm may move or change intensity.

“A greater emphasis on probabilistic forecasts will likely occur in the next few years given the huge consequences that can occur with even just a minute error in the forecast. For instance, a track error of just 2 or 3 miles can make a big difference for communities near the eye as to whether or not they’ll experience storm surge flooding, one of the biggest threats from these storms,” Miketta said.

Furthermore, as the NHC, and its parent organization, the National Oceanic and Atmospheric Administration, continue to improve hazard communication, expect a more direct connection to residents.

“Social media will be taking on a greater role in keeping the public informed concerning storm movement, intensity, and impact, especially among younger people,” Miketta said.

Contact: 609-272-7247

JMartucci@pressofac.com

Twitter@ACPressMartucci

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