Forecasters hope new graphics will help give more accurate alerts

Starting this month, weather forecasters have the ability to use maps to show the direction of movement of low-pressure weather systems, even before they strengthen into tropical storms or hurricanes and cause damage to coastal communities.

Before July 1, on the National Weather Service website, forecasts would indicate the low-pressure areas with a color-coded circle that just showed the system’s location and the percentage chance of it strengthening. Although this provided some indication of potential threats, there was no information about which direction the low-pressure system was likely to take.

“Nobody would know where it was going,” said Ken Graham, meteorologist-in-charge at the National Weather Service in Slidell.

Now, the map will show not only the location of the low-pressure center but also the forecasted path of the system, regardless of whether the system strengthens enough to get a tropical storm or hurricane name.

The advances came as the U.S. dealt with its first hurricane of the season, Hurricane Arthur, which made landfall Friday. The storm proved less damaging than feared but left tens of thousands without power.

Dennis Feltgen, meteorologist and public affairs officer with the National Oceanic and Atmospheric Administration’s National Hurricane Center, said the center started a text version of the five-day tropical weather outlook in 2012.

“The next logical step was to produce a graphic for it,” he said. “The computing power and the accuracy of the models had reached the point where this level of forecasting was reliable.”

It joins a number of other new graphics launched by the National Hurricane Center this year, including a new forecast of potential storm surge flooding maps based on approaching storms. These new graphics got their first public test run as Hurricane Arthur started churning in the Atlantic Ocean before affecting areas along the East Coast during the Fourth of July weekend.

The arrival of Hurricane Arthur is a little ahead of the average for both the first named storm of the season and the first hurricane, according to information from the National Hurricane Center.

On average, based on data from 1966 through 2009, the first named storm appears around July 9, with the first hurricane showing up around Aug. 10. Although the Atlantic Basin hurricane season officially runs from June 1 to Nov. 30, the height of the season is usually late August into late September.

Forecasters with the National Oceanic and Atmospheric Administration’s Climate Prediction Center predicted that this year would be either an average or below-average season. Other university-based forecasts, such as Colorado State University’s Tropical Meteorology Project and the Coastal Carolina University Hurricane Landfall Outlook Program, agree that it’s likely it could be a below-average year.

At the same time, forecasters are quick to point out that it takes only one storm, like Hurricane Andrew in 1992, to make it a destructive and busy season.

Follow Amy Wold on Twitter, @awold10.

SW