Increased storm activity forecast through mid-September

For the latest information on storm activity in the Cayman Islands, as well as information on how to prepare for hurricane season, visit Storm Centre.

Tropical cyclone activity in the Atlantic basin is forecast to be above average during the first half of September, according to researchers with the Colorado State University Tropical Meteorology Project.

Current storm patterns indicate favourable conditions for Atlantic hurricane formation and intensification from 2-15 Sept., considered a peak period for the storm season, forecasters wrote.

The CSU forecast analyses Accumulated Cyclone Energy, a measure of the total wind energy produced by a tropical system over its lifetime. Standard ACE activity for 2-15 Sept. would fall between 12 and 34 ACE. Forecasters expect activity in coming weeks to surpass that range.

Hurricane Nana, which passed earlier this week, was estimated to generate 2-3 ACE.

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As of Thursday afternoon, forecasters were observing three other systems located off the northwestern coast of Africa. Those systems were forecast at a 70%, 40% and 20% probability of formation between Thursday and Tuesday.

“The global models vary considerably with how much intensification these systems may undergo, but each of these could generate low to moderate levels of ACE depending on their exact track,” CSU wrote in its forecast.

Long-range modelling found the possibility of “vigorous easterly waves emerging off of Africa” in coming weeks.

Vertical wind shear, which can inhibit hurricane formation, is expected to be below normal over the eastern tropical Atlantic and Caribbean over the next two weeks. Slightly elevated shear, however, is forecast for the central tropical Atlantic.

As of 3 Sept., the 2020 season had produced 15 named storms, including five hurricanes and one major hurricane. An average season, based on data taken from 1981-2010, would produce 12.1 named storms, 6.4 hurricanes and 2.7 major hurricanes.

Overall, 2020 is forecast by CSU to produce 24 named storms, including 12 hurricanes and five major hurricanes.

CSU’s next two-week hurricane season forecast will be released on 16 Sept.

More rainfall for Cayman

Meanwhile, in Cayman, local forecasters say above-average rainfall is expected across the Cayman Islands over the next three months.

The National Weather Service released the latest predictions in its September Weather Bulletin.

“The usual rainfall range for Sep-Oct-Nov is 483.1 to 652.0 mm (19-25.6 inches),” reads the bulletin. “The Aug-Sep-Oct outlook calls for 60% probability of above-normal rainfall.”

Forecasters say they also expect above-average temperatures, which could lead to heatwaves.

The bulletin reads, “Warmer than usual conditions are forecast for the Cayman area. For Sep-Oct-Nov, there is a 30% chance for at least 7 heatwave days.”

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