After the hyperactive 2017 Atlantic hurricane season—certainly the busiest and most destructive since at least 2005, and among the top five in the historical record—coastal residents in the United States, Caribbean Islands, and Mexico are understandably wary of what lies ahead. The Atlantic season officially begins this year on June 1.
Unfortunately, there’s been a lot of hype. Back in March, forecasts of severe doom-and-gloom went viral on Facebook (but had absolutely no credibility). More recently, some news publications have assessed the seasonal outlooks from various organizations and have sounded the alarm. For example, the widely read web site predicted that this, “Hurricane season may be even worse in 2018 after a harrowing 2017.”
That’s unlikely. Phil Klotzbach of Colorado State University, who produces the oldest, and most widely recognized seasonal hurricane forecast, expressed dismay at this kind of reporting. “Yeah, that’s way too much hype,” he told Ars. “Even if our forecast is perfect, we predicted seven hurricanes versus climatology, which is six. So, nothing like 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 tallies both the duration and intensity of all tropical storms and hurricanes to measure the overall activity during a given season. This year, Klotzbach is forecasting an ACE value of 130 in the Atlantic basin.
Tough to predict
The reality is, the forthcoming Atlantic season is not an easy one to predict. This is primarily because neither a strong El Niño or La Niña seems likely to develop in the Pacific Ocean. These large-scale patterns play a role in helping to govern 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, 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 major forecasts released since then have been more or less in line with Klotzbach’s predictions—calling for near-normal, or moderately above normal activity in the Atlantic this year. For example, the average prediction for the number of hurricanes this year is seven (same as Klotzbach’s forecast). There were 10 hurricanes in 2017.
The next Colorado State forecast will be issued at the end of this month. If anything, conditions closer to the beginning of hurricane season seem to be trending toward less overall activity. “Since early April, we’ve seen some anomalous cooling in the tropical Atlantic, so I’d say that the odds of an active season have gone down a bit since then,” he said.
As ever, the usual caveats with seasonal forecasting apply. Such forecasts are a scientific endeavor to forecast weather patterns months into the future and therefore are experimental rather than truly predictive. Also, it can be a “slow” hurricane season for the Atlantic, but if a storm hits the region where you live it was a busy year for you.