FORECASTS

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Now let’s talk about storm surge

Traditional forecast graphics the ones you normally see being passed around online by Floridians in the days before a storm don’t highlight one particular threat that has accounted for roughly half the deaths from landfalling cyclones over the past five decades: storm surge.

To address that, the National Hurricane Center in 2017 started issuing a storm surge watch and warning graphic “intended to separate” the advisories from the previously existing wind watches and warnings, “and serve as a call to action.”

Similar to a hurricane watch, a storm surge watch is the possibility (there’s that word again) of life-threatening inundation from rising water moving toward land within a specific area and generally within 48 hours of a tropical cyclone. Forecasters can also issue a watch earlier if conditions could limit the time needed to make surge preparations.

A storm surge warning means there’s a danger (more certain now) of life-threatening surge inundation generallywithin36hours.

Forecasters release their storm surge graphic roughly 30 minutes after each hurricane advisory goes live. It’s subject to change every six hours, according to the National Hurricane Center. A storm surge watch is denoted in magenta, while a storm surge warning is in lavender.

Right now, the graphic takes into account myriad variables, including surge flooding, tides, land elevation, trackuncertainties and floodingasa resultofleveefailures.

But it’s also noteworthy what the graphic doesn’t take into account: freshwater flooding from rainfall and wave action during a high stormsurge.

On 11 a.m. Sept. 27, the day before Ian made landfall in Southwest Florida, a storm surge warning in mind when looking at those dizzying spaghetti plots, like where these models come from and what they’re used for stretched along the majority of Florida’s Gulf Coast. The graphic published by the National Hurricane Center depicted the areas under watchesandwarnings.

Meteorologists use models in everyday weather forecasting Some of these models forecast the mundane from afternoon storms to a burgeoning cold front. Supercomputers run these models, calculating complex formulas to understand what is happening in our atmosphere.

But in the hurricane season, they are just as useful to forecasters in telling them where a monster storm could end up.

The hurricane center uses what it considers to be the top models for forecasting hurricanes, which come from the United States and globally.

“Life-threatening storm surge from Ian is increasingly likely along the Florida west coast where a storm surge warning is in effect, with the highest risk from Fort Myers to the Tampa Bay region,” the hurricane center warned.

Less than 24 hours later, the Gulf of Mexico began swelling toward Southwest Florida. On Fort Myers Beach, scientists would ultimately log up to 15 feet of storm surge. In Lee County alone, the surge killed 36people.

What to know about models used for forecasting

There are enough forecast models to make your head spin. Yet, when the hurricane season starts, we look to our favorites, scrutinizing thin, colorful lines and their predicted paths.

In reality, there is no one Holy Grail model.

There are a few things to keep

There is an ongoing debate over which is the best weather model. It generally comes down to two: the GFS (the Global Forecast System) or the European model (the European Center for Medium-Range Weather Forecasts).

However, the quarrel over the best model isn’t particularly helpful. Forecasters rely on multiple models, not just one The hurricane center’s forecast track generally takes the average of five or six of the world’s most accurate weather models to create its forecast.

For forecasters, there’s an advantage to having multiple models because it helps them better understand the uncertainty of a storm.

“If you look at the top six models, pretty much any of those things could come true,” Jeff Masters, a meteorologist for Yale Climate Connections, previously told the Tampa Bay Times. “Don’t put your trust in any particular one. The average of them is usually going to be the best forecast.”