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  • Writer's pictureBryan Norcross

An extreme hurricane threat for the southeastern Caribbean islands

You would think it was August. Exceptional and record-setting Hurricane Beryl is charging toward the southeastern Caribbean Islands. It’s up to Category 3 strength and still organizing. Hurricane warnings have been issued for the islands where the threat is the highest. On the current schedule, the weather will deteriorate tonight, and the maximum impact will be during the day tomorrow.



A hurricane warning does not mean that hurricane conditions will definitely occur. It means that there is a danger that they COULD occur based on the best information available. Therefore, full hurricane preparations are required where the warnings are posted.


Storm surge of up to 9 feet above normal tide levels will pound eastward-facing shorelines.


Now that Hurricane Beryl is well organized, and the steering high-pressure system to the north is strong and stable, we can have higher confidence in the track. Hurricane warnings extend from Tobago in the south to St. Lucia in the north plus Barbados. Nearby islands will also feel significant effects. Since Beryl is a small hurricane in diameter, the worst of the extreme winds will likely not impact all of those islands. But it's too early to know the exact maximum impact zone.


This is an extraordinary and unprecedented event for this time of year. Barbados and the islands of the southeast Caribbean are no strangers to hurricanes. But only once has a hurricane traversed this zone in June in the record book. That was in 1933, which ranks as one of the busiest hurricane seasons on record, and it was a Category 1.



The upper-level wind pattern is extremely conducive for Beryl to strengthen as it approaches the islands and passes into the Caribbean. By late Tuesday, however, it will be facing a bit of a headwind, which is why the National Hurricane Center is showing some weakening on days 4 and 5 in the forecast.


This may be a harbinger of things to come this hurricane season, or it might be something more like a freak event that Beryl and the system that's following it (called Invest 96L) formed just under the Saharan dust plume. Normally, the dust impedes development of systems as they move off Africa this time of year.


Confidence is high that Beryl will track across the central Caribbean until midweek and not impact Puerto Rico or the Virgin Islands in a significant way. The track’s bend to the north is due to a dip in the jet stream moving off the US East Coast, which will tug pull the storm north. High pressure will then build across the southern US, which should push Beryl south again as it moves into the western Caribbean.


After that, things get fuzzier. The odds favor high pressure holding it to the south of the US. But if the high pressure moves out of the way too soon, there is some chance the storm could slow down and possibly turn into the Gulf. There are too many variables, including the speed of the storm, its intensity, and the movement of the blocking high to predict with confidence what will happen at the end of the week.


For now, our concern is for the affected Caribbean Islands. Hurricane Beryl has the potential to be a catastrophic event if its relatively narrow band of intense winds impacts a populated island. With luck, the strongest winds will find a gap between the islands, which sometimes happens.



Next in the Atlantic: The system, officially called Invest 96L, is two days behind Beryl. If this system attains winds of 40 mph, it will be named Tropical Storm Chris (or possibly Debby, depending on what happens in the Gulf). Potential-Chris will find similarly conducive upper winds to the regime that allowed Beryl to get so strong, though Saharan dust could be a bigger player.


Dust is very nearby potential-Chris’s circulation center, which might well slow development.


On the current schedule, potential Chris or whatever it is, will impact the eastern Caribbean islands about Wednesday. Because the disturbance is still disorganized and dust is in the picture, the strength of the system at that time is unknowable.

If Beryl coming through the islands as a Category 4 hurricane is extraordinary, the idea of two storms in two days on similar tracks is insane. We'll see.



In the Gulf: The system the National Hurricane Center has been calling Invest 94L has a decent chance of turning into a tropical depression or tropical storm in the southern Gulf of Mexico. But it would have to happen today. The system is reasonably well developed, but it will be operating so close to land and have such a short window over the water that it may or may not have time to organize.


The threat with this system continues to be to Mexico and Central America, where extreme amounts of rain have fallen over the past few weeks.


This flurry of tropical activity is at least partially related to a pulse called the MJO that propagates around the Earth every 30 to 60 days. When it gets to just the right position, it enhances the likelihood of storms developing. The current pulse is quite weak, but it is positioned for maximum Atlantic storm-enhancing impact. The pulse will move on as we get into July. Hopefully, things will calm down, but let’s not count on it.

 

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