The 8th Atlantic Hurricane Season of the 21st Century is in the past. It ended on the 27th of August, and with it came an unusually strong El Niño. That drove temperatures in the tropical waters of the tropical Atlantic to much higher levels than normal, resulting in strong hurricane activity.
How did the El Niño affect our hurricane season? We can track the trend in the Atlantic using two different pieces of data. The first is the normal result of storm formation since 1950. These results are influenced by La Niña, so we know that the Atlantic season normally sees 12 named storms. We also know that during El Niño, storm activity increases, but then the El Niño ends, and activity declines. Here are the data over the past century.
During El Niño years, the Atlantic sees approximately 12 named storms. This number falls dramatically the following year. Therefore, during El Niño years, we think the number of tropical storms and hurricanes increased. We know a lot about El Niño, so we can take the projected average for a hurricane season and project that average based on previous years.
Here’s what the 2017-2018 El Niño contributed to the season:
Meteorologists projected a potential 14 named storms, 7 hurricanes, and 4 major hurricanes in the 2016-2017 season based on the average relationship between season numbers and years of El Niño. The 28 named storms, 10 hurricanes, and 8 major hurricanes we saw was 2 more named storms, 2 more hurricanes, and 4 more major hurricanes than what we were expecting due to El Niño.
While this season was mostly up and down for storms and hurricane activity in the Atlantic basin, there were a few unusual occurrences. For one, the season actually ended one day short of the normal end date, causing a paper correction to the averages. Since this season wasn’t entirely unusual, a paper correction based on it wasn’t as big a deal for those who simply followed the Atlantic in September. The other strange event was Hurricane Florence.
Hurricane Florence’s first landfall was exactly six years after Hurricane Earl. Earl made landfall on September 11, 2012, five years after landfall from Frances and Hanna in the eastern Atlantic. The first time Florence made landfall was also exactly six years after Superstorm Sandy hit in October 2012. We didn’t see a hurricane of any kind during September for most of the 21st Century. And it broke all of that. Florence did a home run to all of these records for September landfalls. September 11 had been the first day of a tropical system landfall in an Atlantic hurricane season since Michael ten years prior. And September 13 was also the first day of a hurricane making landfall since the record-setting Labor Day hurricane Wilma hit Florida in 2005.
So what will we see in the future? As we saw this year, forecasting this year’s Atlantic hurricane season is difficult, as we only get two years of data due to El Niño. Here’s our best forecast right now for next year’s hurricane season. Our path of El Niño will continue to impact the Atlantic basin for the next three months. However, the year 2018 doesn’t look like it was affected much by El Niño. It did bring some unusual events, including the lack of a hurricane of any kind in September, but it was a hurricane season that followed a long run of strength in the Atlantic. So, if we look back on our longer history, it feels more or less normal. If we’re right, next year’s Atlantic season will be almost the same as this year in terms of named storms and hurricanes. But things may be a little different compared to past seasons, including this one.