Caribbean storm could become Tropical Storm Zeta

Air Force Reserve Hurricane Hunters were dispatched to fly into and investigate the system Friday afternoon, which may give models a better idea of where this storm could be headed.

If the disturbance does get a name, though, which appears increasingly likely, it would tie with 2005 for the greatest number of named storms to ever occur in a hurricane season. Any storms beyond that would bring us deeper into the Greek alphabet than we’ve ever gone before.

Shortly after lunchtime on Friday, heavy showers and thunderstorms were affecting the southern coast of Cuba and western Jamaica. The system’s center of circulation was located about 100 miles south of the Cayman Islands.

The Cayman Islands’ weather agency warned of “possible flooding of low lying areas” with heavy downpours bubbling up across the island.

On infrared satellite imagery, a pinwheel of showers and thunderstorms could be seen slowly orbiting about a common center. The system appeared rather balanced, meaning that thunderstorm activity was present all around the low-level center. This could help it to organize a central vortex and jump-start the process of intensification.

The system has exhibited healthy outflow of air aloft, which is suggestive of a strengthening storm. Outflow is essentially the “exhaust” of a tropical weather system, such as a hurricane. The more efficiently it can evacuate spent air up out of and away from it, the easier it is for the storm to pump in moisture-rich air at the surface and intensify.

The jury is out when it comes to the computer models and whether Invest 95L will end up intensifying. The models, however, have struggled to even “keep up” with real-time observations, forcing forecasters to rely more on experience.

The most likely scenario would be for the system to slowly consolidate, becoming a depression or named tropical storm, Zeta, before passing over Cuba this weekend. Heavy rain would be possible for the Cayman Islands and southern Cuba during this time frame.

Then an inflection point in the system’s intensity would be reached on Sunday as it encounters two obstacles at the same time. The first will be its passage near or over Cuba, which could disrupt the circulation.

At the same time, wind shear, which is the change in wind speed and/or direction with height, from a weak cold front passing through could impede the storm. Too much shear can induce weakening.

In the event it holds together or is able to re-intensify after a passage over land, heavy rain will be possible over Florida. Ocean heat content, a metric that describes how much energy is contained in near-surface ocean waters to sustain a storm, is low across most of the Gulf of Mexico — except for north of the western tip of Cuba and around the Straits of Florida. There is a low chance that Zeta could become a hurricane, a scenario shown by one or two computer models.

The bottom line? Hurricane season isn’t over until it’s over (officially that’s Nov. 30), and this is a particularly tricky forecast.

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