Weekly Synopsis

Forecast Discussion

UPDATED:  16 October 2026 | 7:00 p.m.

KEY MESSAGES
 

• An upper-level trough continues to enhance low level moisture tonight
• Shower activity is expected to persist through the weekend as weak disturbances move through the region, and a frontal system approaches western Cuba.
• Forecast confidence decreases early next week as models suggest the possible development of a low-pressure area over the southwestern Caribbean, which could influence moisture and rainfall across the region.

Nowcast (Tonight)

Shower activity is currently evident on radar over areas south, west, and northwest of Grand Cayman. This activity is being supported by an influx of low-level moisture interacting with a surface trough and an upper-level trough across the region.

The upper-level trough is expected to remain in place, maintaining a favorable diffluent pattern aloft. This will continue to support lift and enhance atmospheric instability, resulting in isolated to scattered thundershowers as the night progresses across the Cayman Islands and surrounding waters.
Short Term Forecast (Saturday through Monday)

A decrease in precipitable water (PWAT) values on Saturday is expected due to limited moisture availability and generally resulting in reduce shower activity across the area. A frontal boundary will move into the southeastern United States, gradually weakening the ridge as the parent anticyclone shifts eastward into the central Atlantic. At the same time, the front is forecast to advance southward toward South Florida. As the frontal system progresses, an induced trough is expected to develop near the Cayman Islands by Saturday afternoon while the front approaches western Cuba. In addition, a possible prefrontal trough moving ahead of the front may enhance low-level convergence and increase the likelihood of showers across the Cayman area. Meanwhile, an area of low pressure developing over the southwestern Caribbean is expected to support broad cyclonic flow across much of the basin. Aloft, an upper-level trough will move across the Yucatan Channel by Saturday afternoon, followed by a second upper-level trough associated with the frontal system moving into the northwestern Caribbean by Sunday. These features may provide additional support for unsettled weather in the region.

As the front reaches western and central Cuba, a deep plume of tropical moisture characterized by high PWAT values is expected to become concentrated along and ahead of the boundary, resulting in enhanced moisture over those areas. By Monday, the frontal boundary is expected to dissipate over western Cuba, with much of the associated moisture weakening and remaining north of the Cayman Islands. In its wake, a high-pressure system building over the southeastern United States is forecast to strengthen and gradually steer the remaining moisture southward across the Cayman Islands by Monday afternoon. Model guidance indicates a mere 10mm of rainfall accumulation during these three days.
Extended Forecast (Tuesday and Wednesday)

Attention then turns to the southwestern Caribbean, where model guidance indicates the development of a semi-organized area of low pressure accompanied by a significant increase in precipitable water (PWAT). This feature is forecast to drift slowly toward the northeast by Tuesday night, potentially enhancing moisture and instability across portions of the northwestern Caribbean. In contrast, further analysis using the European model does not depict a similar evolution during this period. As a result, confidence in the timing, structure, and eventual track of any potential low-pressure development remains low, and the situation will continue to be monitored. Regardless of development a few showers are forecast into Wednesday.

Marine Forecast

Given the forecast for a decrease in winds speeds over the next few days, seas are expected to be slight to moderate with wave heights between 1-4 feet through the forecast period. In periods of showers, seas may become occasionally choppy in and around those areas. 

Forecaster
Neverson-Jack