The 2019 Atlantic hurricane season officially began on June 1 and runs through November 30, although Subtropical Storm Andrew made 2019 the fifth consecutive year to have a named storm form outside of that time frame. The Atlantic season includes the Atlantic Ocean, Gulf of Mexico, and the Caribbean Sea.
At the start of the season, the forecast was not bad. Back in April, the Colorado State University Tropical Meteorology Project predicted a below-average Atlantic hurricane season, forecasting 13 named storms and 5 hurricanes. In early May, the U.S. National Oceanic and Atmospheric Administration’s Climate Prediction Center forecasted that this year’s hurricane season would be “near-normal.” The NOAA’s forecast included 9 to 15 named storms, of which 4 to 8 were predicted to become hurricanes. It was also predicted that 2 to 4 of those hurricanes would be “major” hurricanes, which includes category 3, 4 or 5 storms with winds of 111 mph or higher. An average hurricane season produces 12 named storms, of which 6 become hurricanes, including 3 major hurricanes.
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The predictions were based on several competing climate conditions. El Niño conditions were in effect at the start of the season, with the anticipated effect of suppressing the intensity of the hurricane season. But it was also expected that warmer-than-average sea-surface temperatures in the tropical Atlantic Ocean and Caribbean Sea—an increasing trend since 1995—combined with an enhanced west African monsoon season would counteract the El Niño effect and increase hurricane activity. About 85 percent of all major Atlantic hurricanes are traceable to unstable airflow, known as “tropical waves,” originating along the African coast and moving westward across the Atlantic.
Two major hurricanes may not sound like a bad prediction for this season, but the predictions are for the overall seasonal activity, not landfall. In 2018, only two major hurricanes developed (Florence and Michael), but both struck land and caused billions of dollars in damage and multiple deaths.
Thankfully, the first half of the season was uncharacteristically slow, with only two named storms (Andrea and Barry), just a fifth of the typical activity for that point in the year. However, on August 8, NOAA updated its seasonal outlook in advance of the usual peak of the season. Forecasters increased the likelihood of an above-normal Atlantic hurricane season to 45 percent, up from its May forecast of 30 percent. The prediction for the number of named storms also increased to up to 17, including a prediction for 5-9 hurricanes and 2-4 major hurricanes. The end of El Niño in the Pacific Ocean and the associated return of neutral conditions contributed to this revised forecast and increased the likelihood of above-normal activity.
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As predicted, storm activity in the Atlantic has been steadily increasing since late August. Just since September 14, there have been five named storms, breaking a record for the most Atlantic named storms on record between September 14 and September 23. Three of the twelve storms named so far this year have reached hurricane status; one of those—Dorian—was a major hurricane. Just a few days ago, Lorenzo became the twelfth named storm of the 2019 Atlantic hurricane season, joining Tropical Storms Jerry and Karen. That makes three named storms simultaneously active for the second time this year. On September 4, Dorian, Fernand, and Gabrielle were active simultaneously. Jerry has since weakened, though it’s still considered dangerous as it passes by Bermuda. Karen and Lorenzo are getting stronger. After dumping torrential rains on Puerto Rico, Tropical Storm Karen is strengthening as it moves northwest across the southeastern Caribbean and is predicted to turn towards Florida. Lorenzo is also rapidly strengthening and is predicted to become a large and powerful hurricane in the eastern and central Atlantic.
As we saw last year, even a hurricane season with a relatively low number of hurricanes can be devastating when the right storm hits the wrong place. With more than two months to go in this year’s season, and activity increasing, 2019 could turn out to be a more destructive year than initially expected.
