With its having already set records, forecasters are confident that the 2020 Atlantic Basin hurricane season will take a quite serious turn for the worse after a post-Isaias pause.
In its updated outlook, released Thursday, the National Oceanic and Atmospheric Administration predicted that by the time the season ends on Nov. 30, it will have produced 19 to 25 named storms, those with winds of 39 mph or better.
Of those, it said, seven to 11 would become hurricanes, with winds of at least 74 mph, with three to six of those “major,” with peak winds of 111 mph or more. The names might well outrace the alphabet.
“This year, we expect more, stronger, and longer-lived storms than average,” said Gerry Bell, the government’s chief hurricane forecaster, adding that conditions suggest an “extremely active” season.
The NOAA outlook tracks closely with the forecast update issued Wednesday by Colorado State University, which called for up to 24 named tropical storms, with 12 hurricanes.
The long-term averages are 11 tropical storms and six hurricanes.
The records for named storms, 28, and hurricanes, 15, both were set in 2005, the year of Katrina and one of the deadliest and costliest seasons in history.
In the early going, 2020 bears some haunting similarities. Philip Klotzbach, chief of the hurricane forecasting team at Colorado State, says conditions in the basin are similar to those of 2005.
Sea-surface temperatures in the basin, which includes the Gulf of Mexico and the Caribbean Sea, are generally well above normal and are the fourth warmest in records dating about 40 years, Klotzbach said. Warm waters help fuel tropical storms.
On the other side of the globe, waters in the tropical Pacific are cooler than usual, which is favorable for hurricanes in the Atlantic. When the Pacific waters are warmer, they generate shearing winds that can dampen storm formation in the Atlantic.
Klotzbach said the level of shear in the Atlantic is the second lowest it has been in a period of record dating to the late 1970s.
While the tropics should be quiet for the next week, a major pattern change over the Atlantic will result in steering winds in the upper atmosphere that could guide storms bounding off the African coast toward the Caribbean and U.S. coasts, said Dan Kottlowski, hurricane expert at AccuWeather Inc.
AccuWeather is likely to bump up its outlook to call for 20 to 24 named storms, senior meteorologist Paul Walker said.
The 2020 season already has set records for early occurring named storms. Isaias was No. 9; on average, the ninth storm doesn’t occur until Oct. 4.
Bell said a factor driving the storm traffic is that the basin is in the warm phase of a phenomenon known as the Atlantic Multi-decadal Oscillation, which favors active seasons. Historically, the phases have lasted from 25 to 40 years.
This one took hold in 1995, another one of the most-active seasons on record. That one also is on Klotzbach’s analog list for this year.