Weather experts have forecast little prospect of tropical storm or hurricane development in the waters near the Cayman Islands before September.
In its two-week forecast issued on 19 August, Colorado State University said the Atlantic is likely to stay quiet between 19 August and 1 September.
The university’s tropical meteorology team assigned a 70% probability of below-normal activity, a 28% probability of near-normal activity and just 2% chance of above-normal activity.
For this period, the team defines below-normal as fewer than seven units of Accumulated Cyclone Energy, a measure that combines the strength and duration of storms across the basin.
There were no active tropical cyclones in the Atlantic when the outlook was published.
However, in its 2pm forecast on 23 August, the US National Hurricane Center flagged a tropical wave off the west coast of Africa.
It said an area of low pressure could form in association with the wave “early this week”.
“Environmental conditions are forecast to be marginally conducive for development, and a tropical depression could form by the middle to latter portions of the week,” it added.
The CSU forecast said development in the western Atlantic, the area of the basin that includes the Caribbean waters, “seems highly unlikely”, citing strong vertical wind shear that tends to tear developing storms apart.
The team pointed to a strong El Niño as the dominant brake on activity.
The Pacific climate pattern, which the National Oceanic and Atmospheric Administration (NOAA) said emerged in June, drives up wind shear across the tropical Atlantic and suppresses storm formation.
The continued quiet is notable. Late August normally marks what the university called “the real ramp-up” for the season, as tropical waves rolling off West Africa begin to hold together over open water.
The short-term outlook sits within a season that has run well below its long-term average.
The NOAA’s most recent update, in early August, maintained its call for a below-normal season, narrowing its forecast to between 7 and 13 named storms, of which two to six could become hurricanes and up to two major hurricanes, and putting the odds of a below-normal season at 75%.
The basin has so far produced three short-lived tropical storms – Arthur, Bertha and Cristobal – and no hurricanes. Forecasters were nonetheless careful not to sound an ‘all-clear’.
The climatological peak of the Atlantic season falls between mid-August and mid-October, and a below-normal season is not a storm-free one.
Hazard Management Cayman Islands and the Cayman Islands National Weather Service both stress that a single system, even a passing tropical storm, can bring damaging winds, flooding rain and dangerous surf to low-lying Grand Cayman and the Sister Islands.
Residents are encouraged to keep hurricane plans and supplies current, and to monitor official sources rather than early-model speculation once the season deepens.
Colorado State University’s next two-week outlook is due on 2 September, covering the period to 15 September.
