NOAA
After the hyperactive 2017 Atlantic hurricane season—certainly the busiest and most destructive since at least 2005, and in the top five in the historic record—coastal residents in the United States, the Caribbean islands and Mexico are understandably wary of what lies ahead. . The Atlantic season officially starts on June 1 this year.
Unfortunately, a hype has arisen. In March, predictions of grave doom and gloom went viral on Facebook (but were by no means credible). More recently, some news publications have reviewed the seasonal outlook of various organizations and sounded the alarm. For example the much read Guardian website predicted that this “2018 hurricane season could be even worse after a harrowing 2017.”
That’s unlikely. Phil Klotzbach of Colorado State University, which produces the oldest and most recognized seasonal forecast for hurricanes, expressed dismay at this type of reporting. “Yeah, that’s way too much hype,” he told Ars. “Even if our forecast is perfect, we predicted seven hurricanes versus climatology, that’s six. So nothing beats what was predicted last year.”
From a more rigorously quantifiable perspective, the 2017 Atlantic hurricane season produced an “accumulated cyclone energy” value of 225 units, well above the normal value of 90 to 100 units. This ACE value corresponds to both the duration and intensity of all tropical storms and hurricanes to measure overall activity during a given season. This year, Klotzbach predicts an ACE value of 130 in the Atlantic basin.
Hard to predict
The reality is that the coming Atlantic season is not easy to predict. This is mainly because no strong El Niño or La Niña appears to be developing in the Pacific Ocean. These large-scale patterns play a role in controlling pressure levels and wind shear in the tropical Atlantic. For example, a strong El Niño typically means much higher wind shear values in the Atlantic Ocean, which is more hostile to the development and intensification of hurricanes.
Klotzbach released his most recent forecast for the 2018 season in early April. Most of the more than a dozen other key predictions released since then have more or less aligned with Klotzbach’s predictions — calling for near-normal or moderately above-normal activity in the Atlantic this year. For example, the average forecast for the number of hurricanes this year is seven (similar to Klotzbach’s forecast). In 2017, there were 10 hurricanes.
Plot with current seasonal forecasts for the number of hurricanes for the Atlantic basin from different groups.
Seasonalhurricanepredictions.org
The next weather forecast for the state of Colorado will be published at the end of this month. If anything, conditions closer to the start of the hurricane season seem to be leaning toward less general activity. “We’ve seen an anomalous cooling in the tropical Atlantic since early April, so I’d say the likelihood of an active season has decreased a bit since then,” he said.
As always, the usual caveats with seasonal forecasts apply. Such forecasts are a scientific attempt to predict weather patterns months in the future and are therefore experimental rather than truly predictive. It could also be a “slow” hurricane season for the Atlantic, but if a storm hits the region where you live, it’s been a busy year for you.