Despite lower-than-average numbers of tropical storms and hurricanes for the Atlantic in 2017, parts of the southeastern United States are likely to be at risk for multiple major impacts.
"The Gulf of Mexico coast, especially central and eastern areas including all of Florida, will be the greatest areas of concern for direct and indirect impacts from tropical storms and hurricanes during the 2017 season," according to AccuWeather Hurricane Expert Dan Kottlowski.
"A secondary area of concern may be from Cape Hatteras, North Carolina, on south," Kottlowski said.
If a hurricane or tropical storm makes landfall or direct impact, it could unleash damaging winds, flooding rain and storm surge flooding. If a tropical system passes nearby offshore, locally heavy rain, gusty winds, rough surf and beach erosion could be indirect impacts.
Following direct or indirect impacts in the Southeast, tropical systems could then make their way into the northeastern United States as a heavy rain threat or stir up wind and water along adjacent coastal areas in the North Atlantic.
The key for this concern is based on an anticipated strong area of high pressure over the west-central Atlantic. This high pressure area represents a large counterclockwise flow of dry air.
"The flow is likely to guide more tropical storms and hurricanes farther west than average," Kottlowski said.
The slightly lower-than-average numbers of tropical storms and hurricanes are based on the spread of slightly cooler-than-average waters over the main part of the Atlantic basin at the start of the season as well as disruptive winds generated by the onset of a weak El Niño this summer.
However, water temperatures over prime development areas of the Atlantic may surge to above average, like that of 2016, and the start of El Niño could be delayed.
A slow onset of El Niño is a factor that would likely contribute to a higher number of storms overall in the season, according to AccuWeather hurricane experts. If El Niño were to form earlier, then the number of storms during the entire 2017 hurricane season could be well below average.
Even if water temperatures in key development areas of the Atlantic are below average, the water is likely to be warm enough to support some development and maintain tropical systems in most cases.
The threat for early-season tropical development exists and there is one key area to watch closely, Kottlowski stated.
"The main area to watch for a potential tropical storm or hurricane during June is likely to be centered on the northwestern Caribbean Sea," Kottlowski said.
Any system that develops near there would most likely be carried westward toward Mexico, but there is a chance of a turn toward the U.S. Gulf Coast area as well, Kottlowski stated.
This same general area could remain a prime area for development in July.
AccuWeather meteorologists are projecting the formation of 10 tropical storms, five of which may become hurricanes and three may become major hurricanes. Three tropical storms and/or hurricanes are projected to have a direct impact on the U.S.
On average there are 12 tropical storms, six hurricanes, three major hurricanes and three to four direct impacts on the U.S. per year.
Should the trend toward below-average water temperatures continue and/or if El Niño comes on faster and stronger than anticipated, the number of hurricanes, tropical storms and direct impacts could be lower than projections.
The Atlantic hurricane season begins on June 1 and ends on Nov. 30.
AccuWeather first released its Atlantic hurricane season forecast in early April 2017.