The science of tropical storm forecasting is getting better and more refined each year, which has changed the challenge forecasters face to one of making sure the public understands their risk from an approaching storm.
“There’s so much information available that people get overwhelmed,” said Ken Graham, meteorologist-in-charge with the National Weather Service in Slidell. “There’s weather information galore and people are getting confused.”
With weather websites, weather channels, weather apps and more weather information available, people now more than ever have the ability to “shop” for the storm outcome they’d like to see.
Graham said he still hears people make comments such as: “It’s never flooded here before;” “It’s just a Category 1 storm;” or “It looks like we’re safe since my app has the storm going to Florida.”
Computer models forecasting potential storm tracks are widely available, but they’re not all created equal — some having stronger records of accuracy than others.
All too often, if one line of a “spaghetti model” — a weather map with colored lines that show different computer model predictions of where the storm will go — shows a storm tracking away from the state, some residents may choose to believe that model even if it has proven in the past to be unreliable to scientists.
“There’s only one official forecast for this country,” Graham has said, referring to his organization, the National Weather Service. The National Weather Service and the National Hurricane Center are both part of the National Oceanic and Atmospheric Administration.
During Hurricane Isaac, for example, Graham said he knew a man who gathered as much information on the storm as he could from a multitude of sources.
One website focused on a computer model that predicted the storm was headed toward Alabama, but later he found another computer model that showed the storm had turned toward Louisiana.
“He couldn’t make a decision because there was so much information,” Graham said. “He was paralyzed by it.”
Instead of focusing on the lines in a computer model, Graham suggested people take a broader approach when deciding how to prepare for a storm.
“We have to get people to get back to looking at that cone,” he said, referring to the National Weather Service’s forecast cone.
“The cone is not a cone of impact.”
Instead, the forecast cone is what the National Hurricane Center uses to show a general range of the likely path a tropical storm will travel.
What the cone means is that there’s a 33 percent chance the storm will come ashore on one side of the centerline drawn in the cone, a 33 percent chance it could come ashore on the other side of the centerline, and 33 percent chance it could come ashore outside the cone altogether, he said.