TAMPA, Fla. (WFLA) — Seasonal forecasters are calling for another active hurricane season in the Atlantic, with forecasts like NOAA and Colorado State University forecasting up to, or perhaps more than, 20 storms.
Now, joining the active forecast chorus, is the European Model Ensemble. It’s latest Atlantic Ocean seasonal forecast calling for 11 hurricanes (the average is seven) and an accumulated cyclone energy (ACE) index of around ~225 units.
While 11 hurricanes is active, but not necessarily abnormal, the forecast of an ACE of 225 units is somewhat rare and, if it verifies, would be considered hyperactive. It’s one of the most aggressive June forecasts ever put out by the model.
The number of ACE units is calculated by the energy produced by each tropical system in each ocean basin in a given year. The numbers of storms, intensity of storms and longevity of storms are all factored into the calculation of that number.
A few caveats should be noted. While seasonal forecasts, like the European, have improved greatly in recent years, they are still subject to great uncertainty.
Also, although it is possible to attain clues as to where storms may have a greater tendency to form in each basin, there is still no way to forecast exactly where storms will track. So regardless of how active or inactive a season is expected to be, it’s a good idea to be prepared each year.
Now you might be asking why forecasts call for an active season ahead? Primarily it has to do with the cold tropical eastern Pacific Ocean – what is known as La Niña. During May, an index which measures the intensity of La Niña recorded the lowest May value on record.
A recent Max Defender 8 Weather Team analysis found that, over the past 30 years, La Niña’s produce triple the number of hurricanes than El Niño years. In addition, during La Niña the greatest uptick in tropical activity occurs in the Caribbean and SW Gulf of Mexico.
We spoke to an expert on tropical climate prediction, Meteorologist Eric Webb with White Sands, to find out more about the science about why this season is expected to be so active.
“Even if it is not super warm in the Atlantic, as long as it is warmer than what is around it, that’s where you are going to have upward motion, clouds, convection and of course a favorable environment for a tropical cyclone,” explained Webb.
“So by having areas like the Indian Ocean, the Tropical Pacific, the Subtropical Atlantic and the South Atlantic all being near average or below average, that creates a favorable environment for tropical cyclones,” Webb added. “Air has to rise somewhere in the tropics and the only area that is really left is the Atlantic. Essentially it is the only game in town.”
Below is a visualization of what Webb is referring to. Given that the tropics are full of warm and moist water, air tends to rise and form clouds, storms and tropical cyclones. But the specific basins and regions those tropical systems form in is dictated by “relative” warmth. Essentially, the regions that are the most abnormally warm and are adjacent to regions that are cooler then normal will tend to have the best chance of tropical formation.
In the case of the upcoming season it appears that the Western Atlantic basin is the most warm relative to the Eastern Pacific, and thus areas like the Caribbean are favored.
Webb says there are lots of reasons to believe that the Caribbean will be most anomalously active region, especially later in the season, but whether or not these storms reach the Gulf of Mexico around Tampa Bay depends on many other factors.
The bottom line is that we need to be prepared for an impact every hurricane season. In active years the odds are obviously higher. But at this early stage there is no way to know who will be impacted. So there’s no need to panic, as long as we are prepared.
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