Here’s What Will Change With Hurricane Forecasts This Year

Jonathan Belles

Published: April 21, 2020

The cone of uncertainty for what became Hurricane Dorian in 2019. This cone is not a current forecast.

With less than six weeks left until the official start of Atlantic Basin hurricane season, the National Hurricane Center (NHC) has released its list of product changes for the six-month period when hurricanes and tropical storms are most likely to develop.

The first tweaks that the NHC made were to their forecast cone of uncertainty.

The cone of uncertainty refers to the projected path map you frequently see on the internet or television for a given storm.

(MORE: What the Cone of Uncertainty Means)

The cone is made up of circles that encapsulate 66% of the historical forecast track errors over the last five years at each point from three to 120 hours. It does not represent where impacts like surge, wind, flooding or tornadoes will occur.

In fact, most impacts will fall outside the cone of uncertainty within a forecast out to a day or two.

Generally, this error has decreased over the last 10 years, but this year, the cone will remain mostly unchanged.

A few tweaks were made here and there, and you can see the size of those radii below.

The size of the 2020 cone of uncertainty (left) and a sample cone of uncertainty (right). This cone is not a current forecast.

This year's changes were largely focused on helping clarify the forecast: adding a forecast point at 60 hours and turning the storm surge forecast into a graphical format for ease of understanding.

This year, the NHC will add one more of these circles to its cone of uncertainty to help increase the accuracy of the forecast at two-and-a-half days out.

This addition will allow forecasters to add wind speed and wind radii forecasts at 60 hours and will also be included in time-of-arrival and storm surge forecasts.

This increases the accuracy of forecasts, specifically for storms that are expected to turn at this time step. Before 2020, the data at about 60 hours was an "as the crow flies" forecast that just connected the dots between two and three days.

A turning storm would have an actual data point to the left or right of the "as the crow flies" forecast, depending on which direction the storm was turning.

Another addition to the suite of products from the NHC is a graphical depiction of its storm surge forecast.

Before 2019, this forecast of storm surge was given solely in a text format, and users had to figure out where they were located in that text forecast that often uses rather obscure location endpoints.

This graphical depiction of the NHC's storm surge forecast has been a common product offered by weather.com for several years.

The new graphical depiction (on left) of a storm surge forecast issued by the NHC for Hurricane Dorian in 2019. Only text (on right) was included in forecasts prior to 2020.

These changes are a reminder that hurricane season is around the corner, and it is time to prepare.

We know this year's preparations may be hindered by the coronavirus pandemic, but you can also use the pandemic to bolster your supply kits for the months to come.

Having a good supply of non-perishable food items, a mask for dust and germs, a can opener, extra pet food, extra books and games for kids are all things that could be doubled for both a hurricane kit and for living in a pandemic. Of course, don't rush out to get these supplies, but pick them up (or even better, order them online) when you need other things to avoid going out more than necessary.

Here are a few other things you can pick up in preparation for hurricane season.

This hurricane kit could be especially useful in the months ahead.

Most companies that have issued seasonal hurricane forecasts, including The Weather Company, an IBM Business, have predicted above- to far-above-average hurricane and tropical storm activity in the season ahead.

Here is the latest forecast from earlier this month.

Numbers of Atlantic Basin named storms (those that attain at least tropical or subtropical storm strength), hurricanes and hurricanes of Category 3 or higher intensity forecast by The Weather Company, an IBM Business, and Colorado State University compared to the 30-year average (1981 to 2010) and totals from the 2019 season.

And keep in mind that just because hurricane season officially begins on June 1, it doesn't mean that the physics and dynamics of the atmosphere will just come together right on that date.

Named storms have formed before June 1 several times in recent years.

Here are the names that will be given to the tropical storms and hurricanes that form this season:

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.