Keeping an eye to the western Caribbean for next week

No additional threats this week in the wake of Potential Tropical Cyclone Eight

Atlantic tropical cyclone formation points from September 22nd through the end of the hurricane season for the satellite era (since 1966). While storms can still form almost anywhere in the Atlantic, we see a high density of formation in and around the western Caribbean associated with the Central American Gyre (yellow shaded area).

On the one hand, the hurricane season is on track to notably underdeliver on hyperactive seasonal forecasts – measured by overall tropical activity, not storm impacts – predicted by virtually all of the two dozen or so groups that issue such long-term forecasts, including NOAA, the parent agency of the National Weather Service.

After springing to one of the most active starts on record, largely due to Category 5 Beryl in early July, the Atlantic has fallen back to about average activity to-date.

Total tropical activity by month as measured by the Accumulated Cyclone Energy or ACE. The blue line is the total ACE so far in 2024 and the bold black line is the average. After a near-record start in activity early in the season, overall tropical activity in the Atlantic has leveled off to near long-term averages. Credit: Deelan Jariwala/Cyclonicwx.com.

Hurricane Beryl alone accounts for about 58% of the entire season’s activity, though it isn’t uncommon for one big storm to dominate the seasonal statistics (Hurricane Andrew accounted for a full 96% of tropical activity to-date in late September 1992).

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On the other hand, the storms that have formed – and even ones that haven’t – have been especially impactful this season. Just yesterday, a non-tropical area of low pressure designated Potential Tropical Cyclone Eight by the National Hurricane Center moved inland over the Carolinas. Though the coastal storm was not structurally a tropical cyclone as it came ashore Monday afternoon, it had all the calling cards of a named storm, bringing wind gusts to 67 mph to Wilmington and over 18 inches of rainfall in a period of 12 hours, accompanied by historic flooding, to parts of Carolina Beach at the tip of Cape Fear.

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And while the 7 named storms observed so far are below the 9 named-storm-average for mid-September, 6 of the 7 named storms this season have struck land, including 3 U.S. hurricane landfalls, doubling the average annual hurricane landfalls by the mid-point of the season. Needless to say, it’s not felt like a down season at the coast in 2024.

Keeping an eye on the western Caribbean for next week

As we discussed in yesterday’s newsletter, we’ll be monitoring the western Caribbean to start next week. Forecast models have been consistent in showing a sprawling area of low pressure forming around Central America beginning this weekend.

Low pressure track scenarios through next Tuesday, September 24th, from the overnight run of the European forecast model ensemble system. The model suggest possible low pressure development from the eastern Pacific to the western Caribbean and southern Gulf of Mexico, indicating high uncertainty on where the larger low-pressure gyre tries to consolidate, if at all. Credit: Weathernerds.org.

There are more questions than answers on how the storminess evolves next week, but the broad beginnings as part of the Central American Gyre or CAG suggest we not put much stock in individual forecast model runs for now. Expect the single-run forecasts looking out over a week to vary wildly with each new forecast, but broadly speaking, the atmosphere looks conducive for slow development early next week in the western Caribbean and southern Gulf of Mexico. The big question is where exactly does storminess try to consolidate, if at all, as part of the broader circulation.

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For now, it’s just something we’ll need to revisit, but it’s also a good reminder that hurricane season is far from over.

Gordon gone fishing

Gordon has been pulsing with thunderstorms since yesterday over the central Atlantic but hasn’t been able to regain tropical storm status yet.

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The Tropical Depression may re-strengthen later this week but has turned northward and will stay out to sea.


About the Author
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Michael Lowry is Local 10's Hurricane Specialist and Storm Surge Expert.

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