Tropical Storm Don Weakens With Season’s Peak Yet To Come

TAMPA, FL — As the National Hurricane Center continued to keep a close watch on Tropical Storm Don and another system churning in the Atlantic Ocean Tuesday, the season’s peak period of activity had yet to arrive. Forecasters say nearly 80 percent of all tropical storm days on record occur during the eight-week period from mid-August to mid-October each year.

As for Tropical Storm Don, the system was located about 130 miles south-southeast of Barbados as of the hurricane center’s 2 p.m. Tuesday, July 18 update. Don, forecasters say, was starting to pummel the Windward Islands with rain Tuesday afternoon.

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Tropical Storm Don had weakened from packing 50 mph maximum sustained winds earlier in the day. Forecasters at 2 p.m. Tuesday, said the storm was generating sustained winds of 40 mph as it moved west at 20 mph. Tropical storm warnings were in place for Grenada, St. Vincent and the Grenadines. A tropical storm watch had also been issued for Bonaire.

On its current projected path, Don is expected to skirt the northern coastline of South America. Forecasters expect the storm to weaken to depression status at some point on Wednesday.

Meanwhile, a “well-defined low-pressure system” that was located about 1,000 miles west-southwest of the Cabo Verde Islands remained under watch by hurricane center forecasters. That storm was kicking up showers and thunderstorms, according the center’s Tuesday afternoon Tropical Weather Outlook report. Forecasters say some gradual development of the system is possible over the next few days as it moves west-northwest or northwest at an estimated 10 to 15 mph.

Center forecasters say the system has a 30 percent chance of forming more over the next 48 hours. The system, however, is expected to soon encounter conditions that are “forecast to become hostile for development.”

Hurricane Season's Peak Nears

While neither storm poses an immediate, or even likely, threat to the continental United States, both serve as strong reminders that the season’s peak has not yet arrived. Hurricane season technically lasts from June 1 to Nov. 30, but forecasters call the period between mid-August and mid-October the “season within the season.” This eight-week period “is often the most active and dangerous time for tropical cyclone activity,” according to the National Oceanic and Atmospheric Administration.

The eight-week period from August to October is historically responsible for major spikes in tropical weather activity, NOAA said. In fact, it accounts for roughly 78 percent of all tropical storm days on record. It is also the period when 87 percent of the category 1 and 2 hurricane days on record occurred. In addition, this period is responsible for “a whopping 96 percent of the major (category 3, 4 and 5) hurricane days.”

So, what makes this eight-week stretch so special?

“Tropical waves are coming off of the coast of Africa roughly every three days, and the very early and late parts of the year provide additional types of potential seedlings,” NOAA’s website explains.

Other environmental conditions during the peak tend to be more conducive for storm development, as well. The factors that align during the peak period include wind, temperature and moisture. Wind shear that might rip disturbances apart in May, for example, tend to weaken by late August, NOAA said.

“This minimum in the shear combines with favorable thermodynamics – ocean temperatures in the deep tropics that increase with each day of summer sun, warmer air temperatures, and increasing atmospheric moisture,” NOAA explained. “When the dynamics and thermodynamics are in sync, as they often are from mid-August through early October, disturbances like African tropical waves can easily strengthen.”

The conditions gradually become less ripe for development in mid-October when increased wind shear tends to reappear and water and air temperatures cool.

Above-Average Season Forecast

Although it might seem unlikely given only four named storms so far, NOAA is predicting an above-average number of named storms in 2017. NOAA forecasters projected earlier this year the 2017 season will produce 11 to 17 tropical storms. Of the 11 to 17 tropical storms, about five to nine of them are expected to become hurricanes, Ben Friedman, NOAA’s acting administrator, said in announcing his agency’s 2017 predictions. Two to four major hurricanes with maximum sustained winds of at least 111 mph are anticipated, as well.

“There is a potential for a lot of Atlantic storm activity this year,” Friedman said.

See also: Above-Normal Hurricane Season Predicted By NOAA

An average hurricane season produces about 12 named storms of which six become hurricanes. Three of those storms generally become major hurricanes.

With hurricane season upon us, Friedman stressed the need for people to get ready. “We cannot stop hurricanes, but we can prepare for them.”

Residents readying for the ongoing season can get tips and advice on the federal government’s Ready.gov website. Folks in the Tampa Bay area can also check out this related story: Hurricane Season 2017: What Tampa Bay Area Residents Need To Know. The Atlantic hurricane season runs through Nov. 30.

Graphics courtesy of the National Hurricane Center and NOAA