“We are now entering the peak months of August through October,” said Gerry Bell, NOAA’s lead hurricane season forecaster. “Historically, 95 percent of hurricanes, and most major hurricanes, occur during this time frame. That’s why we do an update to the outlook. An above-normal season has the highest chance of occurring.”
NOAA is now predicting between 10 and 17 named storms, five to nine of which are expected to become hurricanes. That includes Andrea, a nondescript subtropical storm in May that affected only the fish, and Barry, a low-end Category 1 hurricane that dropped two feet of rain in Louisiana and Mississippi. More important, the revised outlook is calling for two to four major hurricanes, referring to storms that achieve Category 3 status — or greater.
“In addition, the storms we end up getting could be longer-lived and stronger than we had forecast back in May,” said Bell, who referred to the early demise of an El Niño pattern that is typically hostile to hurricanes. “Winds now are forecast to be much more hospitable” to hurricanes.
Earlier Wednesday, NOAA announced that El Niño had dissipated and issued its final El Niño advisory.
Bell added that climate model forecasts support NOAA’s predicted bump up in hurricane activity.
Bell emphasized that it’s impossible to predict this far ahead whether these storms will hit land. “That comes down to local weather patterns at the time the storm’s approaching,” he said. That can’t be done before a storm has developed. “We just can’t make seasonal landfall predictions.”
The season may seem to be off to a slow start, but in reality that’s normal. Strong hurricanes rarely form before mid- to late August.
“During June and July, most of the storms we get come from disruptions in the jet stream, or trailing frontal boundaries,” Bell said. “But the pattern switches in August. We start getting storms from tropical waves that come off the coast of Africa. It’s a completely different formation mechanism.” And those are the storms that ride all the way across the Atlantic, gathering strength and, on occasion, metastasizing into monsters.
Bell discussed Gulf of Mexico water temperatures, which have been warmer than average as of late. “The entire tropical Atlantic is running half a degree Fahrenheit warmer than average.” But Bell said that water temperatures in the gulf “really aren’t a factor for seasonal activity.”
“You can have an above-normal season without a single storm in the gulf,” he said. “Once we get a system in the gulf, then we take a look there more closely.”
Bell emphasized the need for early preparedness, suggesting that residents along the Gulf Coast and the Eastern Seaboard take advantage of the next few quiet weeks now before a storm develops.
“This applies to both coastal and inland residents,” he said. “It’s not only about the numbers. It only takes one storm.”
Bell says that we’ve been in the midst of a more active period of hurricane activity since 1995. “There’s a whole set of conditions” that give rise to that, according to Bell. “Most of these periods last 25 to 40 years at a time.”
The past few years have experienced a spike in hurricane activity. Included was Hurricane Michael in October, the first Category 5 U.S. landfall since Andrew in 1992. Florence dropped nearly three feet of rain in North Carolina, coming on the heels of a 2017 season that featured Harvey, Irma and Maria. Bell warns this year could be another memorable one.
“We have more confidence that this season could produce quite a bit of activity.”