Updated outlook still calls for busy storm season
Published 8:48 am Monday, July 11, 2022
By Skip Rigney
The vast majority of tropical storms and hurricanes in the Atlantic basin occur in August, September, and October. The other three months of the official hurricane season, June, July, and November, are usually relatively quiet.
So, it’s not surprising that the National Hurricane Center says they do not expect any tropical cyclones to develop over the Atlantic Ocean, Caribbean Sea, or Gulf of Mexico during the next five days. However, the consensus among scientists who do seasonal hurricane outlooks is that the heart of the season will once again have an above-average number of tropical storms and hurricanes.
The latest such prediction came on Thursday when the Colorado State University (CSU) Tropical Weather and Climate Research group updated their seasonal outlook. CSU estimates that the June-November 2022 season will have 10 hurricanes (average is 7.2), 20 named storms (average is 14.4 – three inconsequential tropical storms have already been named this season), 95 named storm days (average is 69.4), 40 hurricane days (average is 27.0), 5 major (sustained winds greater than 110 mph) hurricanes (average is 3.2) and 11 major hurricane days (average is 7.4).
Thursday’s update did not change much from the two previous outlooks issued by CSU in early April and early June, nor did their rationale for why this is likely to be another abnormally active season.
One major factor is that sea surface temperatures in the tropical Pacific Ocean remain significantly cooler-than-average, a pattern known as La Niña, and this is expected to continue through the fall. When La Niña is occurring in the Pacific, wind shear is usually weak over the tropical Atlantic, which makes it more likely that storms can get organized and intensify.
Another factor pointing toward a busier-than-normal season is that the high altitude winds over tropical Africa appear especially favorable for producing stronger middle and lower altitude disturbances known as tropical or easterly waves. Most major hurricanes have their origins as tropical waves that move off the African coast and cross the Atlantic.
As is usually the case in July, sea surface temperatures are still relatively cool in the tropical central and eastern Atlantic, but they will warm to levels supportive of hurricane formation in August and September.
As is true by July almost every year, the Gulf of Mexico, Caribbean Sea, and the Atlantic around the Bahamas are already more than warm enough to support hurricane development. In fact, the Gulf of Mexico is ahead of schedule for July with sea surface temperatures running one to two degrees warmer-than-average.
While there is no way to predict exactly where hurricanes will go before they form, CSU does estimate that this season there is a 49 percent chance that at least one major hurricane will hit somewhere along the U.S. Gulf Coast west of the Florida Peninsula. That’s roughly a 20 percent higher chance than the average season over the last century.
One begins to wonder if Atlantic hurricane seasons are like radio personality Garrison Keillor’s fictitious Lake Wobegon where “all the children are above average.” In fact, 13 seasons in the last 30 years have had a below-average number of tropical storms and hurricanes. It’s just that we haven’t had a season like that since 2015.